ISSN NUMBER: 1938-7172
Issue 5.3 VOLUME 5 | NUMBER 3

Editor:
Michael A. Fiedler, PhD, CRNA

Contributing Editors:
Penelope S Benedik, PhD, CRNA, RRT
Mary A Golinski, PhD, CRNA
Gerard Hogan Jr., DNSc, CRNA
Alfred E Lupien, PhD, CRNA
Lisa Osborne, PhD, CRNA
Dennis Spence, PhD, CRNA
Cassy Taylor, DNP, DMP, CRNA
Steven R Wooden, MS, CRNA

Guest Editor:
Sandra Larson, PhD, CRNA

Assistant Editor
Jessica Floyd, BS

A Publication of Lifelong Learning, LLC © Copyright 2011

New health information becomes available constantly. While we strive to provide accurate information, factual and typographical errors may occur. The authors, editors, publisher, and Lifelong Learning, LLC is/are not responsible for any errors or omissions in the information presented. We endeavor to provide accurate information helpful in your clinical practice. Remember, though, that there is a lot of information out there and we are only presenting some of it here. Also, the comments of contributors represent their personal views, colored by their knowledge, understanding, experience, and judgment which may differ from yours. Their comments are written without knowing details of the clinical situation in which you may apply the information. In the end, your clinical decisions should be based upon your best judgment for each specific patient situation. We do not accept responsibility for clinical decisions or outcomes.

Table of Contents

AIRWAY
Preoperative endoscopic airway examination (PEAE) provides superior airway information and may reduce the use of unnecessary awake intubation
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CARDIOVASCULAR
  Preoperative cerebral oxygen saturation and clinical outcomes in cardiac surgery
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EQUIPMENT & TECHNOLOGY
Peristaltic compression of the legs reduces fluid demand and improves hemodynamic stability during surgery: a randomized, prospective study
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GENERAL
Factors associated with and consequences of unplanned post-operative intubation in elderly vascular and general surgery patients
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Hand contamination of anesthesia providers is an important risk factor for intraoperative bacterial transmission
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REGIONAL ANESTHESIA
A multicenter, randomized, triple-masked, placebo-controlled trial of the effect of ambulatory continuous femoral nerve blocks on discharge-readiness following total knee arthroplasty in patients on general orthopaedic wards
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PEDIATRIC ANESTHESIA
Incidence of perioperative adverse events in obese children undergoing elective general surgery
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Airway
Preoperative endoscopic airway examination (PEAE) provides superior airway information and may reduce the use of unnecessary awake intubation

Anesth Analg 2011;112:602-7

Rosenblatt W, Ianus AI, Sukhupragarn W, Fickenscher A, Sasaki C


Abstract

Purpose To determine if a preoperative endoscopic airway examination (PEAE) of upper airway pathology would change the anesthesia provider’s airway management approach.

 

Background Patients presenting with upper airway pathology can be particularly challenging to the anesthesia provider. The presence of lesions at the base of the tongue, epiglottis, glottis, or larynx cannot be seen with a routine airway examination. Furthermore, these lesions may obstruct the airway and may make mask ventilation and intubation difficult. The ASA Difficult Airway algorithm recommends an awake intubation if there is significant risk for loss of control of the airway during induction of anesthesia. However, overuse or unnecessary awake intubation may lead to surgical delays and can be uncomfortable for the patient.

 

Methodology One hundred forty (n = 140) ASA I to IV patients scheduled for elective surgery of the upper airway, including direct laryngoscopy (DL), were enrolled. Exclusion criteria included disease of the bilateral nares, coagulopathy, or high risk for aspiration. History, physical, and demographic data was recorded. A standard airway examination was completed on all patients. The anesthesia provider then decided whether they felt the patient could be intubated after induction of anesthesia (I-Asleep) or that an awake intubation was recommended (I-Awake). The provider also recorded the recommended airway device to be used. Choices included direct laryngoscopy or video laryngoscopy (DL/VL), or a flexible fiberoptic intubating bronchoscope (FOB).

 

Patients were asked about the level of discomfort they experienced with previous flexible nasopharyngoscopy examinations in the ENT clinic using a 0 (no discomfort) to 10 (extreme discomfort) scale. Next, each nare was sprayed with oxymetazoline and topical anesthesia accomplished using 100 mg of 5% lidocaine ointment. A nasal PEAE was performed in a semi recumbent position using a 65-cm-long, 3.7-mm-diameter FOB (Karl Storz, Endovision, Culver City, CA) fitted to a camera. The FOB was advanced until the tip of the epiglottis was visualized. The FOB was manipulated to obtain visualization of the right and left pyriform sinuses, vallecula, and vocal cords. Patients were asked to vocalize to examine movement of the true vocal cords. All PEAE examinations were videotaped. Patients were asked to rate PEAE discomfort on a 0-10 scale.

 

The anesthesia provider then recorded the presence or absence of the following: (1) a single-plane optical path to laryngeal inlet, (2) a mass or anatomic distortion that might prevent proper seating of a supraglottic airway device, (3) an anterior airway lesion that might be traumatized during DL/VL. The anesthesia provider then recorded whether the patient should be intubated awake (PEAE-awake) or that they could be intubated after induction of anesthesia (PEAE-asleep). The anesthesia provider then transported the patient to the operating room and the plan for tracheal intubation was carried out based on the PEAE results. Delayed operating room entry time in minutes, and success or failure of the airway management plan was recorded. Four months later a blinded anesthesia provider examined the PEAE recordings and recorded a recommendation for PEAE-awake or PEAE-asleep. The primary outcome was the change in the airway management plan based on the PEAE results. Secondary outcomes included patient discomfort scores and operating room delays caused by PEAE. Statistical analysis was appropriate.

 

Result A total of N = 138 patients were included in the analysis. Two were excluded for missing data. Care was distributed among seven anesthesia providers. The majority of the patients were men (74%) with a mean age of 59 years (range, 38-79 years), with a BMI of 27 kg/m2 (range, 15-36 kg/m2). Reasons for surgery included lesions of the larynx/vocal cords (35%), base of the tongue (19%), supraglottic (10%), and other lesions (36%). A majority of patients had a history of radiation and/or surgery to the head and neck (58%). Proposed surgeries included DL and biopsy (52%), soft neck dissection (14%), and/or base of tongue surgery (9%).

 

After the standard airway examination, the anesthesia provider indicated that a majority of the patients (68%; n = 94) could be intubated after induction of anesthesia (I-Asleep). In 32% of patients (n = 44) an awake intubation was recommended (I-Awake).

 

The change in induction plan after PEAE was 26% (n = 36, P <0.05), with a majority of patients initially in the I-Awake management plan changed to a PEAE-Asleep (n = 28). Eight patients initially assigned to I-Asleep were changed to an awake FOB after the PEAE (Figure 1). The device chosen for intubation was a DL/VL in 56% of patients (n = 77). FOB was chosen for 43% of cases (n = 60). One patient had severe airway distortion and was intubated with an awake retrograde wire intubation. Most patients (82%) were intubated after induction of anesthesia. Only 18% (n = 24) required awake intubation based on PEAE results. There was no significant change in airway device after the PEAE. At the 4 month video review the PEAE plan assignments changed in only 1.5% of patients (2 of 138, P = 0.42).

 

 


Figure 1. Airway management plan based on PEAE results

Figure 1

Note: Percentages are proportion of total sample (N = 138).

 

 

After the usual preoperative airway examination, but before the Preoperative Endoscopic Airway Exam, the anesthesia provider felt that an awake intubation (I-Awake) was appropriate in n = 44 patients. This I-Awake group (n = 44) was significantly older (64 ± 10.2 y vs. 56.7 ± 10.9 y; P <0.001) when compared to the I-Asleep group. The I-Awake group was more likely to have had a history of major airway surgery (75% vs. 51.1%; P =0.008), a shorter thyromental distance (6.4 ± 1.3 cm vs. 6.9 ± 1.5 cm; P = 0.03), limited head extension (≤ 35 degrees: 38.1% vs. 19.1%; P <0.001), smaller interincisor gap (3.9 ± 1.4 cm vs. 4.8 ± 0.9 cm, P < 0.001), and a higher grade Samsoon and Young airway exam score (P < 0.001). The patients in whom an awake intubation was still planned after the PEAE exam (Table 1) had a significantly smaller interincisor gap, higher Samsoon and Young airway exam score, and a more frequent history of major airway surgery when compared to those whose plan changed from with a planned awake intubation to an asleep intubation based upon the PEAE results.

 

 


Table 1. Change in plan from I-Awake to PEAE-Asleep

 

No change in plan

(n = 28)

Change in plan

(n = 110)

P value

History Major Airway Surgery

22 (78.6%)

59 (53.6%)

0.017

Age in years

64.6 ± 12.3

57.6 ± 10.7

0.003

Interincisor Gap, cm

4.1 ±1.2 

4.6 ± 1.1

0.044

Samsoon & Young Score

2.79 ± 0.8

2.2 ± 0.8

0.002

 

 

Patient discomfort scores were significantly less compared to their previous office exam (2.5 vs. 4.9, P <0.05). The PEAE evaluations did not delay the start of cases. In 83% of cases, the PEAE procedure was completed before the operating room was ready for the next patient. In the remaining cases, the PEAE procedure only delayed the case by 3 minutes. No emergent airway situations were encountered, and all intubations were accomplished based on the PEAE proposed plan. No patient experienced oxyhemoglobin desaturation and there was no need to change the airway device chosen based upon PEAE results.

 

Conclusion The airway management plan was changed in 26% of patients based on the PEAE results. In patients with airway pathology, a PEAE may be essential in identifying those patients who truly need an awake intubation. PEAE may be a useful tool for other populations with potential difficult airways.

 
 

Comment

 

I believe the results of this demonstrate that a PEAE may be an additional tool anesthesia providers can incorporate into their preoperative evaluation. The investigators found that based on the PEAE exam in patients with upper airway pathology, the proposed intubation plan (awake or asleep) was changed. They found that a majority of these patients did not need an awake intubation. However, the most important finding was the identification of n = 8 patients whose airway plan changed from an I-asleep to an awake intubation based on the PEAE results. This tells me that the standard airway examination did not identify significant airway pathology that may have lead to an impossible mask ventilation and intubation, respectively.

 

There are a few limitations to this study. First, the investigators combined Direct Laryngoscopy and Video Laryngoscopy devices into one group for their analysis. First-time intubation success has been shown to be significantly higher with VL (i.e., Glidescope) when compared to traditional direct laryngoscopy. I would have liked to know what the breakdown was for the use of these two devices in patients in the PEAE-asleep group. Second, it was not clear to me if all patients in the PEAE-awake group were intubated with an awake fiberoptic or a DL/VL. I assume the former, but further information would have helped clarify this. Finally, the investigators reported the mean airway exam score; results would have been more meaningful if they had presented the median (min, max) airway classification (i.e., MP I to IV).

 

It is important to point out that many of the patients who were in the PEAE-asleep group still had an asleep fiberoptic intubation. This is probably because the investigators were concerned about the airway pathology and difficulty with DL/VL, but they felt that the patients could be easily mask ventilated. The important take home message from this is that anesthesia providers should maintain their skills with fiberoptic intubation.

 

I think PEAE has a place in the preoperative evaluation of patients with suspected airway pathology. Future randomized studies are needed to confirm these findings. Additionally, PEAE should be investigated in other populations with predictors for difficult intubation (i.e., severe sleep apnea). If anesthesia providers wanted to incorporate PEAE into their preoperative evaluation process it probably would be better to complete the exam in a preoperative anesthesia clinic prior to the day of surgery. This minimizes unnecessary delays in preparing equipment and patient preparation on the day of surgery.

Dennis Spence, PhD, CRNA


The views expressed in this article are those of the author and do not reflect official policy or position of the Department of the Navy, the Department of Defense, the Uniformed Services University of the Health Sciences,  or the United States Government.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011




Cardiovascular
Preoperative cerebral oxygen saturation and clinical outcomes in cardiac surgery

Anesthesiology 2011;114:58-69

Heringlake M, Garbers C, Kabler J, Anderson I, et al.


Abstract

Purpose The purpose of this study was to determine if preoperative cerebral oxygen saturation values (ScO2) may be used for risk stratification in cardiac surgery. This objective was accomplished by determining the relationship between preoperative room air and oxygen enriched ScO2 values, preoperative cardiopulmonary function, and postoperative morbidity and mortality.

 

Background ScO2 monitoring is increasingly used to assess the adequacy of frontal cortex oxygen delivery compared to oxygen demand in patients undergoing cardiac surgery. Scores of research studies show cardiac surgery patients have improved outcomes and decreased length of hospital stay when intraoperative ScO2 is maintained within 20% of the patient’s baseline value and above an absolute low ScO2 of 50%.  However, sparse data is available about the ability of preoperative ScO2 levels to predict a patient’s risk for morbidity and mortality.

 

Methodology All patients older than 18 years having on-pump cardiac surgery at the University of Lubeck in Germany from January 1, 2008 to December 31, 2008 were considered for inclusion in this prospective, cohort, observational study.  ScO2 values were determined with an INVOS 4100 or 5100 cerebral oximeter (Somanetics, Troy, MI). In scheduled patients, ScO2 was measured while on the cardiac surgery ward prior to sedation. ScO2 measurements were obtained with the patient at rest and in a semi-recumbent position, initially breathing room air then followed with an escalating concentration of oxygen enriched air until no further increase in arterial hemoglobin-oxygen saturation was observed. Emergent and intubated patients’ ScO2 measurements were obtained on arrival to the operating room, without regard to preoperative administration of sedatives and opioids.

 

Information regarding demographic variables, medication history, medical history, surgical variables, EuroSCORE (see notes), New York Heart Association grade, and measures of cardiac performance were assessed. Anesthesia management and cardiopulmonary bypass management was consistent for all patients.  In all, 1,178 patients were included in the study and complete data sets for 984 of these patients were obtained.

 

Statistical analyses were performed on the total group, as well as on a subgroup of 102 patients that had a EuroSCORE >10.  Statistical significance was assessed at the 5% level (p < 0.05).  Comparisons between groups for univariate predictors of mortality and morbidity were performed with Chi Square for categorical variables and with Mann Whitney or Druskal Wallis for continuous variables.  Correlation analyses were performed by Kendall’s tau for scaled variables and by Spearman rank for continuous variables.  Cutoff values for mortality and morbidity were derived from receiver-operating curve analyses.

 

Result Of the total number of patients, 70.5% were male.  The median age was 68 years (59 -74), weight was 81 kg (72-91), and BMI was 27 (24-32).  The median ASA classification was 3 and the median additive EuroSCORE was 5.  Forty one percent (n=484) were graded as New York Heart Association grade III/IV and 59% (n=694) as New York Heart Association grade I/II.  Thirty-day and one-year mortality and major morbidity were 3.5%, 7.7%, and 13.3% respectively. The subgroup of 102 high-risk patients with a EuroSCORE > 10 had a 30-day and one-year mortality of 15.7% & 27.5% respectively, and a 40.2% incidence of morbidity. Risk factors associated with a statistically significant increase in 30-day mortality and morbidity included:

  • increasing age
  • emergency surgery
  • increased duration of cardiopulmonary bypass
  • increased duration of aortic cross-clamp time
  • reduced glomerular filtration rate
  • increased preoperative B-type natriuretic peptide (BNP)
  • increased troponin
  • left ventricular ejection fraction (LVEF) < 50%
  • EuroSCORE > 10
  • preoperative circulatory support
  • active endocarditis.

 

Cerebral oxygen saturation was significantly correlated with LVEF, BNP, troponin, hematocrit, and EuroSCORE.  Patients with a EuroSCORE >10 had room air and oxygen-enriched cerebral oximetry values that were significantly lower than patients with a EuroSCORE < 10.  Patients presenting with an ScO2 < 51% and who showed no increase with supplemental oxygen had significantly higher 30 day mortality and morbidity compared to patients presenting with an ScO2 < 51% who showed an increase with supplemental oxygen (30-day mortality16.4% vs. 2.5%, p = 0.0081; 30-day morbidity 37.7% vs. 14.8%, p = 0.0033).  While the EuroSCORE had better accuracy in predicting 30-day mortality and morbidity in the total cohort, baseline oxygen-enriched cerebral oximetry values had better accuracy in predicting 30-day mortality in the high risk group.

 

Conclusion Preoperative ScO2 levels were related to objective measures of cardiopulmonary function. Low preoperative ScO2 concentrations were associated with an adverse perioperative course.  Oxygen enriched ScO2 values < 50% independently predict short-term and long-term mortality in patients undergoing on-pump cardiac surgery and might serve as a refined marker for preoperative risk stratification in cardiac surgery patients.

 

Comment

While reviewing the research findings, I was struck by how much thinner, younger, and healthier the cardiac surgery patients in Europe are compared to the cardiac surgery patients in my practice.  And, that if I had been practicing in Europe for the last 28 years, I might not need to color my hair! All kidding aside, these findings highlights patient selection as a potential distinction between our health care system and that of other industrialized nations.

 

This study is first and foremost about risk stratification in cardiac surgery, and risk stratification and patient selection go hand-in-hand, even if no one wants to publicly discuss it.  This study shows baseline oxygen-enriched ScO2 to be an additional variable to enhance the accuracy of the Parsonnet, EuroSCORE, or Society of Thoracic Surgeons models that risk stratify cardiac surgery patients.  Accurate risk stratification provides a basis for predicting which patients will benefit the most from a surgical procedure, for measuring the quality of provider services, and for predicting the cost of care.  Risk stratification is at the heart of what Medicare refers to as “value-based care centers.” Medicare’s focus on value-based care represents its newest initiative to reign in health costs. While this point seems more germane for the health policy journals, if implemented, it will no doubt affect how nurse anesthetists and anesthesiologists practice as part of a larger team.

 

CRNAs should know that beginning January 1, 1999 and running through December 31, 2011, Medicare selected centers in Texas, Oklahoma, New Mexico, and Colorado as demonstration sites for cardiac and orthopedic inpatient surgical procedures to test the viability of a new payment system termed “bundled payment.” Under a bundled payment system, all healthcare providers are required to work collaboratively to provide value-based care for a single payment.  Medicare hopes that the single payment approach will spur providers and hospitals to work together efficiently, and will distribute savings among the providers, beneficiaries, and Medicare. While I do not have a crystal ball, if a single payment system became our future, fee-for-service, Medicare Part A and Part B, and medical direction and supervision reimbursement guidelines become our history.  Imagine the ethical, financial, and clinical practice implications!

Sandra Larson, PhD, CRNA


  • The European System for Cardiac Operative Risk Evaluation (EuroSCORE) provides a basic and an advanced method for risk stratification of cardiac surgery patients.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011




Equipment & Technology
Peristaltic compression of the legs reduces fluid demand and improves hemodynamic stability during surgery: a randomized, prospective study

Anesthesiology 2011;114:536-544

Kiefer N, Theis J, Putensen-Himmer G, Hoeft A, Zenker S


Abstract

Purpose The purpose of this study was to evaluate the usefulness of a peristaltic pneumatic compression system applied to the lower extremities on hemodynamic stability in patients undergoing routine scheduled Ear, Nose and Throat (ENT) surgery.

 

Background There are many operative procedures that require the Nurse Anesthetist to be conservative in their fluid volume replacement. This can make treating and controlling perioperative Mean Arterial Pressure (MAP) drops challenging. Anesthesia itself routinely causes hypotension that is often treated with fluid. Patient NPO status or bowel prep could exacerbate the hypotension. The authors theorized that pneumatic compression of the legs might possibly improve hemodynamic stability by preventing venous pooling, facilitating movement of blood volume back to the intrathoracic space and enhancing preload.

 

Methodology A total of 70 patients were enrolled in this study. Subjects were induced using an agreed upon protocol and maintained under general anesthesia. Since blood pressure alone is not an indicator of fluid volume status, a plethysmograph variability index (PVI) capable Pulse CO-Oximetry unit was employed. This is the only currently available noninvasive piece of equipment that can reliably predict fluid responsiveness through variability in plethysmographic wave with respirations. The anesthesia providers were blinded as to who had the compression device on and who did not by the use of a covering frame.  Due to the noise of the unit, it was present and operating for all cases. The researcher did not know whether or not the device was actually on the patient or just under the drape. The compression device was not the normal pneumatic compression anti embolism device which we are all familiar with. This device called LymphPress® (Villa Sana GmbH & Co. Weiboldshausen, Germany) is normally used for the treatment of lymphedema. An IV fluid management protocol was strictly adhered to by all providers.

 

Result There were no statistically significant demographic differences between the treatment and control groups. Patients with a history of clinically significant cardiac disease, impaired renal function, or electrolyte imbalances were excluded.  Only subjects classified by the ASA Physical Status Classification System I or II were enrolled. The authors demonstrated that Peristaltic Pneumatic Compression (PPC) of the legs reduced intraoperative fluid demand and improved hemodynamic stability when used with an event-driven fluid protocol. Study patients on average received 700 mL less of crystalloid than their control counterparts. Arterial hypotension, although similar shortly after induction, became significantly less common later in the case in the treatment group.

 

Conclusion There appeared to be a clear advantage to using Peristaltic Pneumatic Compression to minimize perioperative fluid replacement in healthy adults. Using PPC to improve preload and decrease fluid volume requirements can improve overall stability and remove the need to use catecholamine vasopressors to maintain adequate perfusion. There is a need for more research in this area, but there is great promise that this technology could be employed in cases where fluid restriction is proven to decrease postoperative morbidity or mortality.

 

Comment

This was a very clean and well planned study.  Although the patient population was rather homogenous (all ENT Surgery), the age range was significant (26-62 years). Of interest was that the hypotension experienced immediately after induction of general anesthesia was similar between both the treatment and the control groups. PPC was not effective in preventing or lessening the hypotension sometimes seen with induction. After recovery from induction, PPC was useful in significantly decreasing hypotensive episodes.  The authors estimated that as much as 1500 mL of intravascular volume can be returned to the central circulation using this technique. This would be significantly more effective than either passive leg lifting or trendelenburg positioning.  What I found fascinating was that the effects did not diminish over time.  There could be a significant benefit from this technology, but studies here in the US (in addition to FDA approval) would have to happen first.

Gerard Hogan Jr., DNSc, CRNA


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011




General
Factors associated with and consequences of unplanned post-operative intubation in elderly vascular and general surgery patients

Eur J Anaesthesiol 2011;28:220-224

Nafiu OO, Ramachandran SK, Ackwerh R, Tremper KK, Campbell DA, Stanley JC


Abstract

Purpose The purpose of this study was to describe the incidence and perioperative variables associated with unplanned postoperative intubation (UPI) in elderly patients undergoing vascular and general surgery. A second aim was to examine the association between UPI and 30-day morbidity and mortality.

 

Background There are an increasing number of patients over the age of 65 undergoing vascular and general surgery. Most may be extubated after surgery easily. However, some may require UPI in the postoperative period either from primary respiratory failure or from postoperative complications. UPI may be associated with increased morbidity and mortality. There are limited studies examining factors associated with UPI in elderly surgical patients.

 

Methodology Data from the Participant Use Data File of the American College of Surgeons National Surgical Quality Improvement Program from 2005 to 2008 was used for this study. Data was extracted from the database on patients > 65 years of age. Exclusion criteria included outpatient surgery, BMI ≤ 18 kg/m2, disseminated malignancy, comatose > 24 hours preoperatively; patients with active do not resuscitate orders and those requiring mechanical ventilation within 48 hours of surgery. Patients with missing hospital length of stay, operation time, anesthesia times, and work relative value unit data were excluded. This left a sample of 115,692 patients.

 

The primary outcome was unplanned postoperative intubation (UPI), defined as the need for intubation and mechanical ventilation because of onset of respiratory or cardiac failure manifested by severe respiratory distress, hypoxia, hypercarbia, or respiratory acidosis within 30 days of surgery. Patients were stratified into a UPI or no UPI group. Secondary outcomes included the incidence of post-operative site-specific complications (i.e., soft tissue or deep wound infections, graft failures, bleeding requiring transfusion), and systemic complications (i.e., myocardial infarction, pulmonary embolism, postoperative renal insufficiency) in those with UPI and those with no UPI. Descriptive and inferential statistics were used to analyze the results. Multivariate logistic regression was used to identify pre-operative and intra-operative factors associated with UPI. A P < 0.05 was significant.

 

Result The incidence of UPI was 3.3% (n = 3,866). Overall, the mean age was approximately 75 years, with 25% being octogenarians; 50% were men and 13.6% were ASA ≥ 4. Patients requiring UPI were slightly older, more likely male, and less likely to be functionally independent when compared to those with no UPI (Table 1). Over one-third of patients with a UPI were ASA ≥ 4.

 

Table 1. Patient demographics and operative characteristics

 

No UPI

(n = 111,826)

UPI

(n = 3,866)

P value

Age, yr

74.5 ± 6.4

75.6 ± 6.5

<0.001

Male sex

49.9%

54.9%

<0.001

ASA ≥ 4.

13%

32.6%

<0.001

Functional independent

88.5%

70.2%

<0.001

Recent severe weight loss

3.6%

7.4%

<0.001

Dyspnea

17.8%

30.1%

<0.001

COPD

10.2%

22.6%

<0.001

Active CHF

1.9%

6.3%

<0.001

Recent angina

1.6%

3.5%

<0.001

Renal failure (dialysis)

2.7%

5.8%

<0.001

Medical diagnoses >3

11.4%

24.9%

<0.001

Preoperative length of stay (days)

1.7 ± 4.9

3.9 ± 9.1

<0.001

Emergency surgery

24.6%

30.8%

<0.001

Open/dirty wound

7.6%

11.7%

<0.001

Anesthesia time

202.7 ± 110

254.4 ± 139

<0.001

Work RVU

19.8 ± 9.4

24 ± 11.6

<0.001

Hospital length of stay (days)

7.1 ± 9.8

24.5 ± 21.8

<0.001

Note: RVU = relative value unit. RVU is a measure of operation complexity. Scores range from 0 (least complex) to 95 (most complex).

 

The 30-day mortality rate was 18.6 times higher in those with a UPI (95% CI, 17.2-20.2; P <0.001). Patients with a UPI were 63.4 times more likely to have a delayed ventilator wean (95% CI, 58.8-68.3, P <0.001), and 55.6 times more likely to experience a cardiac arrest requiring CPR (95% CI, 48.9-63.2, P <0.001). Patients with a UPI were also 36.4 times more likely to experience septic shock (95% CI, 33.7-39.4, P <0.001), 26.2 times more likely to have postoperative pneumonia (95% CI, 24.3-28.3, P <0.001), and 6.6 times more likely to require reoperation (95% CI, 6.2-7.1, P < 0.001).

 

Patients requiring reoperation had the greatest odds for a UPI (OR = 4.5, 95% CI, 4.3-4.9, P < 0.001; Table 2). Patients who were functionally dependent, had ascites, required emergency operation, and intraoperative blood transfusion were 1.8 times more likely to experience a UPI (P <0.001). Smoking and COPD were only moderately associated with risk for UPI.

 

Table 2. Patient demographics and operative characteristics

 

OR

95% CI

P Value

Re-operation

4.56

4.29-4.86

<0.001

Intraoperative blood transfusion

1.88

1.64-1.93

<0.001

Preoperative ascites

1.82

1.51-2.11

<0.001

Emergency case

1.78

1.64-1.94

<0.001

Functionally dependent

1.76

1.62-1.91

<0.001

COPD

1.61

1.46-1.78

<0.001

ASA ≥ 4

1.40

1.27.1.50

<0.001

Preoperative renal failure (dialysis)

1.31

1.19-1.52

<0.001

Smoking history

1.12

1.02-1.22

0.01

Note: OR = odds ratio.

 

Conclusion The incidence of UPI was low in elderly patients presenting for general and vascular surgery, despite many having multiple comorbidities. However, a UPI is associated with higher morbidity and mortality. Understanding what risk factors are associated with the need for a UPI may help providers identify those patients in need of close follow-up and early intervention.

 

Comment

This study demonstrated elderly patients with multiple comorbidities who required re-operation after general or vascular surgery were at the highest risk for an UPI. The overall incidence of UPI was low, 3.3%, which is probably a lower rate than seen five to ten years ago. This is probably due in part to advances in anesthesia and surgical care.

 

Results of this study are not surprising; patients with poor functional status and significant comorbidities that are a constant threat to life (i.e., ASA IV) having general and vascular surgery were at the highest risk of UPI. The take away message from this study is that anesthesia providers administering anesthesia to ASA IV elderly patients who require major general (i.e., exploratory laparotomy) or vascular surgery (i.e., abdominal aortic aneurysm repair) should carefully consider the risks and benefits of extubating the patient at the end of the operation. The sickest patients having major surgery, especially re-operations and emergency surgeries, may require continued mechanical ventilation postoperatively. This latter point is especially important given that a UPI is associated with significant morbidity and mortality. Close communication about our concerns with our surgical and nursing colleagues is critical when caring for this patient population.

 

Dennis Spence, PhD, CRNA


The views expressed in this article are those of the author and do not reflect official policy or position of the Department of the Navy, the Department of Defense, the Uniformed Services University of the Health Sciences, or the United States Government.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011





Hand contamination of anesthesia providers is an important risk factor for intraoperative bacterial transmission

Anesth Analg 2011;112:98-105

Loftus R, Muffly M, Brown J, Beach M, Koff M, Corwin H, Surgenor S, Kirkland K, Yeager M


Abstract

Purpose The purpose of this study was to test the hypothesis that bacterial contamination of anesthesia providers' hands (the origin of bacterial transmission) before patient contact places the patient at high risk for infection by transmission of bacteria. Additionally, the secondary aim was to evaluate decontamination practices in the operating room in preventing the transmission of bacteria and other organisms.

 

Background It is imperative that measures are taken in the operating room that prevent transmission of potentially infectious microorganisms to patients.  More specific information is needed regarding how bacterial transmission occurs.  In a previous clinical trial, it was found that the anesthesia environment became contaminated at the end of the anesthetic/surgical procedure more frequently than at the beginning.  It was also discovered that contamination occurred in cases as short as 4 minutes.  Bacterial contamination of the intraoperative and anesthetic surgical environment was associated with an increased risk of patient contamination via the intravenous stopcock set. This in turn was associated with a significant increase in patient mortality.

 

Methodology This research was carried out as a prospective observational study. A total of 92 pairs of operating rooms were randomly selected. The first and second cases of the day in each OR were studied sequentially.  All patients received a general anesthetic according to usual and customary practice. Samples were taken in order to identify bacterial transmission and included 2 sites in the patient anesthesia environment (APL valve and inhalation agent dial on the gas machine) and of each patient’s IV stopcock set.  Additionally, the hands of the anesthesia providers were cultured. Organisms that were found before the start of case 2, and not present before case 1, served as the measure of cleaning efficacy. Transmission events were defined as bacterial organism found at the end of a case that were not present at the start. The following protocol was followed:

  1. Baseline bacterial cultures were taken from the operative environment at the start of case 1, after active decontamination with a quaternary ammonium compound
  2. Using the modified glove juice technique (see notes), samples were obtained from the hands of the anesthesia providers as they entered the OR but before patient contact
  3. Providers used the stopcock sets for all anesthesia medication
  4. At the completion of case 1, the stopcock set and environmental sites were sampled
  5. Baseline cultures for case 2 were obtained after standard OR cleaning following case 1
  6. The hands of the same providers were again cultured when they entered the OR at the start of case 2 but before physical contact with the patient
  7. Cultures of the environment and patient IV stopcock set were obtained again upon completion of case 2
  8. All organisms transmitted to the stopcock sets or anesthesia environment were then compared with samples taken from the hands of the providers

 

Providers were identified as the origin of transmission only if the analysis confirmed that the organism found on the hand of the provider was the same organism found in the stopcock set or the anesthesia environment. All appropriate demographic data pertinent to each operating room case and the study as a whole, was obtained.

 

Results A total of 164 cases were included in the analysis.  There were no differences in patient specific demographic data in those with an intra-operative transmission event versus those without a transmission event.  Regarding bacterial contamination of provider hands, 66% of hands were contaminated with 1 or more pathogens; including MRSA, VRE, methicillin sensitive Staphylococcal Aureus, Enterococcus, and Enterobacteriaceae.  The overall mean number of total colony forming units (CFUs) found on provider hands was 1,045.  There was no difference in total hand contamination by type of provider (physicians and CRNAs).  The magnitude of CFUs found on provider hands before case 1 was greater than that before the start of case 2 (case 1 mean 1,224; case 2 mean 883, (P < 0.001).  Bacterial transmission to the intra-operative environment occurred in 89% of cases. Providers were identified as the origin of this transmission in 12% of cases.  Bacterial transmission to the patient IV stopcock was identified in 11.5% of cases. Anesthesia providers were identified as the origin of this transmission in 47% of cases.  Contamination of the operating room environment (the measurement of efficacy of decontamination processes) occurred in 7% of the ORs analyzed. The link to stopcock contamination was 5%.  One occurrence of intra-operative transmission was identified and was described as:  ineffective decontamination of provider hands before case 1, leading to contamination of the environment and stopcock during case 1, followed by ineffective hand decontamination while interacting with the environment in case 2, followed by contaminated patient IV stopcock set at the end of case 2.

 

Univariate logistic regression analysis identified no independent risk factors for provider-origin transmission.  Independent predictors of environmental contamination not linked to a provider source included:  1) surgery involving first case of the day, 2) anesthesia provider supervision of more than 1 room, 3) increasing patient age, and 4)  discharge to the ICU directly from the OR.

 

Conclusion Provider hand contamination immediately prior to patient care is a source for some, but not all, of the intra-operative contamination observed in this study.  While the spectrum of bacterial contamination found on the hands of the providers was like those described for health care workers in similar environments, the reason for hand contamination was not immediately obvious. Hand washing was already in place with a high compliance rate. Provider hand contamination is an important and modifiable risk factor related to intraoperative bacterial transmission. Anesthesia equipment decontamination processes are another modifiable risk factor.  The first case of the day is associated with a larger magnitude of overall bacterial transmission.

 

Comment

This study validated the importance and necessity of aggressive hand hygiene and decontamination processes for us as anesthesia providers in preventing the transmission of microorganisms to a vulnerable population.  It should motivate us to follow all processes to the best of our ability, as well as encourage collaboration with support departments to assure appropriate decontamination is carried out between cases.  As providers of anesthesia care, we can indeed serve as a significant source of transmission of pathogens to our patients if we don’t follow the correct procedures.

Consider the timing of glove removal or changing gloves between common procedures such as laryngoscopy and adjusting ventilator settings and gas flow. Gloves that became contaminated with secretions while securing the airway, if not changed or removed, could be the source of microorganism transmission to the dials on the ventilator and gas machine. Now consider the next case in that same operating room. If the gas machine was not thoroughly decontaminated between cases, the gas machine dials remain dirty and the potential for transmission from dials to the subsequent patient’s IV stopcock is very real. If decontamination procedures have not been carried out correctly, if hand hygiene is substandard, if gloves are not discarded and clean ones applied between critical tasks; then transmission of pathogens is likely to occur and we have placed our patient's safety at risk. And the induction sequence is only one component of the full range of care we provide for all our patients.

World Health Organization and Hand Hygiene Task Force guidelines recommend performance of hand hygiene before entering the patient room as the number one preventative measure. How well do we adhere to this in the OR and anesthesia setting? This research shows us that it is very likely that organisms are transmitted to the patient as well as our workstations, as we move from room to room. Thorough hand washing and equipment decontamination reduces the risk of such contamination. And lastly, how comfortable are we that our anesthesia workstations have been properly decontaminated between each patient on a consistent and regular basis?  As providers of care, we should be intimately involved in setting policy for decontamination processes, educate each other and those who perform the decontamination processes, and perform regular checks to assure adherence to decontamination procedures.

Mary A Golinski, PhD, CRNA


Sampling of anesthesia provider hands: the dominant hand was submerged for 60 s into a sterile polyethylene bag of modified glove juice formula containing 50 mL of sampling solution (pH 7.9, containing 3.0 g/L NaCl, 0.1 g/L CaC2, 0.2 g/L KCL, 0.1 g/L MgCl2, 0.2 g/L KH2PO4, 1.15 g/L K2HPO4).  This solution neutralizes residual antiseptic on the skin and facilitates identification and quantification of microorganism by dispersing the colonies into single cells, which were counted as colony forming units.  

 

Horizontal transmission: ineffective decontamination of an organism that was left behind by a provider during case 1 that ultimately contaminated the stopcock set of patient 2 during case 2.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011




Regional Anesthesia
A multicenter, randomized, triple-masked, placebo-controlled trial of the effect of ambulatory continuous femoral nerve blocks on discharge-readiness following total knee arthroplasty in patients on general orthopaedic wards

Pain 2010;150:477-84

Ilfeld BM, Mariano ER, Girard PJ, Loland VJ, Meyer RS, et al.


Abstract

Purpose The purpose of this investigation was to determine if an extended ambulatory continuous femoral nerve block (cFNB) decreased the time until three discharge criteria are met after total knee arthroplasty (TKA). The discharge criteria included: (1) adequate analgesia, (2) independence from intravenous opioids, (3) sufficient ambulation to allow home discharge.

 

Background TKA is associated with significant postoperative pain. cFNB infusions have been demonstrated to improve postoperative pain and tolerance of passive range of motion after TKA. Recent research findings suggest that a 4-day cFNB infusion of ropivacaine after TKA decreased the time to meet the above defined discharge criteria by 53% when compared to an overnight only cFNB. Unfortunately, that study was at a specialized, stand-alone, clinical research center with a single nurse for each patient. This study builds on these previous study findings by testing the hypothesis that an extended 4 day cFNB infusion would decrease the time until three predefined discharge criteria were met in a multi-center clinical trial.

 

Methodology This was a prospective, randomized, multi-center, triple-masked, placebo-controlled trial of 80 patients undergoing total knee arthroplasty. Patients were excluded if they had a history of alcohol or opioid dependence, current chronic analgesic therapy, renal insufficiency, morbid obesity, pregnancy, or ASA III status. Preoperatively, all patients had a cFNB placed via the nerve stimulator technique and 40 mL of 1.5% mepivacaine with 100 mcg epinephrine. Patients with a successful catheter placement and sensory block over the femoral nerve distribution were included in the study. Patients were then randomized and stratified by institution/hospital to one of two groups, cFNB or saline group. For surgery, anesthesia was maintained with volatile anesthesia in nitrous oxide and oxygen. After surgery ropivacaine 0.2% at 6 mL/h with patient-controlled bolus of 4 mL and a lockout of 30 min was infused through the cFNB until 0600 hours on postoperative day (POD) #1. All patients received 975 mg acetaminophen every six hours, Oxycontin sustained-release 10 mg every 12 hours, and celecoxib 200 mg every 12 hours. Breakthrough pain was treated with as needed oxycodone 5 mg (pain scores <4) or 10 mg (pain scores ≥4). Pain was reassessed 30 minutes later and intravenous morphine (2 - 4 mg) was administered until pain was < 4. At 0600 hours on POD #1 those patients in the cFNB group had the ropivacaine infusion continued, whereas those in the saline group had normal saline infused at the same settings. Physical therapy was started on POD #1. On POD #2 at 1800 hours a portable infusion pump with the predetermined solutions was initiated at a basal rate of 5 mL/h, bolus dose 4 mL, with 60-min lock-out.

 

The primary outcome in this study was the time from the end of surgery until meeting all three of the following criteria: (1) adequate analgesia (pain <4 on a scale of 0-10), (2) independence from intravenous opioids, and (3) ambulation of at least 30 meters. Fulfillment of these criteria was evaluated at the end of each 8 hour shift. Secondary outcomes included pain scores, supplemental opioid consumption, attaining a standing position without assistance, ambulation distance, and passive knee degrees of flexion and extension. All patients were discharged home or to a rehabilitation center with their perineural catheter infusions in place on or after the morning of POD #3. In the evening of POD #4 the perineural catheters were removed by the patient’s caretakers. Sample size calculations and statistical analysis was appropriate. A P < 0.05 was considered significant.

 

Result A total of 77 subjects completed the study. Group demographic and surgical data were similar. The average age of patients was approximately 64 years, with 74% being male. Surgical duration was around 136 minutes and tourniquet duration 94 minutes in both groups. Patients in the ropivacaine group attained all three discharge criteria a median of 15 hours earlier than those in the saline group (P = 0.028; Table 1). Patients in the ropivacaine group attained pain scores < 4 out of 10 in a median of 18 hours sooner than those in the saline group (P = 0.009). The time to being free of intravenous opioids was 12 hours faster in the ropivacaine group, however this difference was not statistically significant (P = 0.061). No significant differences were noted between the two groups in time to ambulate > 30 meters (P = 0.778); passive flexion and extension, ability to stand unassisted, or oxycodone immediate release consumption between the two groups. Eight percent (8%) of patients in the ropivacaine group required their infusion rate cut in half twice because of persistent quadriceps weakness. Four subjects in each treatment group had their perineural catheters inadvertently dislodged prior to POD #4. Three subjects in the ropivacaine group fell during their perineural infusions (see The association between lower extremity continuous peripheral nerve blocks and patient falls after knee and hip arthroplasty in Anesthesia Abstracts, October 2010). No serious complications occurred and no femoral nerve palsies were noted at the 6-week surgical postoperative visit.

 

Table 1. Primary and secondary outcomes

 

Ropivacaine group

n = 39

Saline group

n = 38

P value

Time to meet all three discharge criteria

47 (29-69) h

62 (45-79) h

P = 0.028

Pain scores < 4 

20 (0-38) h

38 (15-64) h

P = 0.009

Intravenous opioid-free

21 (0-37) h

33 (11-50) h

P = 0.061

Ability to ambulate 30 meters

40 (25-68) h

45 (25-66) h

P =0.778

Note: Results are presented as median (25th-75th percentile) number of hours.

Conclusion Results of this multi-center trial suggested that extending a cFNB from overnight to 4 days decreased the time until readiness for discharge by 20%. This difference was primarily a result of decreased postoperative pain.

 

Comment

This was a well designed, multi-center trial that demonstrates that a 4 day cFNB infusion of local anesthetic results in less pain and a faster time until ready for discharge after TKA. It did not demonstrate improved early functional rehabilitation outcomes (i.e., ability to ambulate 30 meters or better range of motion). It is important to point out that investigators used a multimodal approach, which combined a continuous femoral nerve block (cFNB), around the clock acetaminophen, a COX-2 inhibitor, and sustained-release oxycontin to provide postoperative pain relief. To achieve the same results clinicians would need to follow a similar multi-modal pain management protocol. Furthermore, having an acute pain service staffed with experienced regional anesthesia providers would help maximize the benefits.

 

Investigators in this study used a nerve stimulator rather than an ultrasound-guided technique to place the cFNB in all patients. In many large academic institutions peripheral nerve blocks and continuous catheters are only placed under ultrasound guidance with or without nerve stimulators. Given the cFNB were placed by expert anesthesia providers, I suspect their results would have been similar regardless of the technique used (nerve stimulator alone vs. ultrasound guided). In my experience, using ultrasound guidance to place cFNB catheters increases the success of the block. However, to achieve consistent success anesthesia providers must attain experience with ultrasound guided regional anesthesia, as there is a significant learning curve.

 

As the population continues to age, we are going to see more patients presenting for TKA. If anesthesia providers want to stay on the forefront of innovations and advancements in regional anesthesia then they should become proficient in ultrasound-guided peripheral nerve blocks.

Dennis Spence, PhD, CRNA


The views expressed in this article are those of the author and do not reflect official policy or position of the Department of the Navy, the Department of Defense, the Uniformed Services University of the Health Sciences,  or the United States Government.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011




Pediatric Anesthesia
Incidence of perioperative adverse events in obese children undergoing elective general surgery

Br J Anaesth 2011;106:359-63

El-Metainy S, Ghoneim T, Aridae E, Wahab MA


Abstract

Purpose To evaluate the relationship between obesity and perioperative adverse events in pediatric patients undergoing elective general surgery.

 

Background The prevalence of obesity is rapidly increasing in developed and developing countries. Obesity is associated with significant comorbidities, such as asthma, obstructive sleep apnea, hypertension, hyperlipidemia, and adult coronary artery disease. There is limited published data on anesthetic and perioperative implications of childhood obesity. A few studies suggest that obese children have more comorbidities and are at greater risk for adverse respiratory events when compared to normal weight children.

 

Methodology This was a prospective study of all of pediatric patients between the ages of 2 and 16 years of age having outpatient general surgery procedures in a Pediatric operating room in Alexandria University Hospital, Alexandria, Egypt. Surgeries in the 2-year study (2007-2008) included inguinal hernia, hypospadias, umbilical hernia, undescended testes repair, dermoid cyst, lipomas, and hemiangioma excision. Children were excluded if they had a history of larygo-tracheomalacia or neuromuscular disorders. Children were classified as obese or non-obese using BMI adjusted for sex and age. Baseline demographics, medical comorbidities, and Mallampati classification were recorded. Anesthesia providers recorded the incidence and severity of adverse respiratory events and complications such as the following:

 

  • Significant oxygen desaturation defined as Sp02 <90%.
  • Upper airway obstruction: need for an oral airway to maintain patency of the airway.
  • Difficult mask ventilation graded using a four-point scale –
    • grade 1: ventilated by mask
    • grade 2: required oral airway or other adjunct
    • grade 3: difficult mask ventilation requiring two practitioners
    • grade 4: unable to mask ventilate.
  • Difficult intubation defined as ≥grade II Cormack and Lehane view.
  • Bronchospasm defined as wheezing.
  • Multiple laryngoscopy attempts.
  • Incidence of coughing, laryngospasm, aspiration, postoperative vomiting, and unplanned hospital admission.

 

The primary outcome of this study was to determine outcomes associated with adverse perioperative events in obese pediatric patients. For the analysis, comparisons were made between obese and non-obese patients within each age group stratum. Descriptive and inferential statistics were used to analyze the results. Multiple regression was used to calculate the relative risk for the occurrence of Mallampati airway class >II and adverse respiratory events, while controlling for age. A P < 0.05 was significant.

 

Result A total of 1,465 children were enrolled in this study. Of these, 10.5% (n = 154) were obese and 89.5% (n = 1,311) were non-obese (including normal and simply overweight). No significant differences were noted in gender, duration of anesthesia or PACU stay between obese or non-obese children (P = NS). Overall, obese children had a significantly higher ASA status, higher incidence of asthma, sleep apnea, and a Mallampati III airway (P <0.05; Table 1). In 36% of cases, the anesthesia provider changed their planned anesthetic technique because of the child’s obesity. The most common change in technique was an intravenous (IV) or rapid sequence induction (only significant in 13-16 yr group) (P < 0.05). The frequency of intubation was also significantly higher (P < 0.01).

 

The frequency of adverse respiratory events was more common in obese children in almost all age groups (Figure 1). There was a higher incidence of oxygen desaturation, grade 2 mask ventilation, airway obstruction, and incidence of bronchospasm in obese children; especially in those with asthma) (Table 2; P<0.05). Adverse respiratory events were more common in younger children. Overall, there was a significantly higher frequency of respiratory events in all obese age groups, except the 13-16 age group.

 

Obese children were 8.34 times more likely to have a Mallampati classification > II (95% CI, 4.62-15.06, P <0.05), with children between the ages of 5-8 years of age having the greatest risk of being Mallampati III or IV (RR: 11.23, 95% CI, 3.88-32.5, P < 0.05). Obese children ages 9 - 12 were at 1.6 times greater risk of experiencing any adverse respiratory event when compared to non-obese children (RR: 1.61, 95% CI: 1.15-2.24, P < 0.05). Subgroup analysis revealed that older and younger children were not at higher relative risk for any adverse respiratory events. Overall, obese children were 1.8 times more likely to have asthma (95% CI, 1.2-2.9, P < 0.05), and 4.0 times more likely to have sleep apnea (95% CI, 2.4-6.8).

 

Conclusion Obese children had a higher incidence of oxygen desaturation (<90%), difficult mask ventilation, airway obstruction, and bronchospasm when compared to non-obese children. The risk of adverse respiratory events was much higher in obese children, especially those who were younger.

 

 

 

Table 1. Demographics and anesthetic technique in non-obese and obese children

Age (yr)

2-4

5-8

9-12

13-16

 

Non-Obese

(n=287)

Obese

(n=23)

Non-Obese

(n=611)

Obese

(n=34)

Non-Obese

(n=252)

Obese

(n=75)

Non-Obese

(n=161)

Obese

(n=22)

Males (%)

64.8

69.6

66

67.6

67.1

68

66.5

68.2

BMI (kg/m2

17.8

27.8**

17.36

29.1**

19.34

31.1**

19.54

32.2**

ASA III (%)

4.9

21.7**

5.2

17.6**

4.7

18.7**

4.9

18.1**

Asthma (%)

14.3

26.1*

13.9

23.5*

13.5

21.3*

13

18.2*

Sleep apnea (%)

5.2

21.7**

5.2

17.6**

4.7

18.7**

4.9

18.1**

Mallampati III (%)

1.4

17.3**

1.2

14.7*

1.9

17.3**

1.2

13.6*

IV induction (%)

24.7

43.5*

25.1

41.2*

24.6

40*

24.2

36.4*

Intubation (%)

14.3

57.1**

14.4

48.6**

14.3

50.7**

14.9

50**

Note. *P < 0.05. **P < 0.01.

  

 

 

 

Table 2. Comparison of perioperative events in non-obese and obese children (%)

Age (yr)

2-4

5-8

9-12

13-16

 

(%)

Non-Obese

(n=287)

Obese

(n=23)

Non-Obese

(n=611)

Obese

(n=34)

Non-Obese

(n=252)

Obese

(n=75)

Non-Obese

(n=161)

Obese

(n=22)

DI

2.1

7.8

1.9

8.8

2.4

6.7

3.1

3.5

Multiple DL

2.4

4.3

2.5

2.9

1.9

2.7

2.5

3.4

Grade 2 MV

3

21.7**

2.6

20.6**

2.4

20**

3.7

22.7**

Coughing

3.8

13*

4.1

14.7*

4

12*

4.3

13.6*

AO

14.3

26.1*

14.2

23.5*

14.3

24*

14.3

22.7*

Laryngospasm

3.5

4.2

3.6

2.9

3.6

2.7

3.7

4

Bronchospasm

1.7

8.7**

1.8

8.8**

1.6

6.7*

2.4

9.1*

Bronchospasm Asthma

7.3

33.3**

7

25**

8.8

18.7**

9.5

25**

Desaturation

6.6

17.4*

6.5

14.7*

6.7

14.7*

6.8

13.6*

Unplanned admission

2.9

4

1.9

2.9

2

1.3

1.8

0

Note. *P < 0.05. **P < 0.01. DI = difficult intubation; DL = direct laryngoscopy; MV = mask ventilation; AO = airway obstruction; A = in asthmatics. Desaturation was < 90%.

 

 

Figure 1. Comparison of any adverse respiratory event in non-obese and obese children

Figure 1

Note. *P < 0.05. N = non-obese; O = obese. 

 

 

Comment

Childhood obesity is becoming a health problem in the United States and in developing countries such as Egypt, where this study took place. Administering anesthesia to obese pediatric patients can be challenging because they may present with significant comorbidities such as sleep apnea and asthma. It can also be challenging to obtain intravenous access and airway management may be difficult. This was an interesting study because I think similar results would be found in the United States.

 

However, there are a few limitations to this study. First, the authors chose to define a difficult mask ventilation and airway obstruction as a need to place an oral airway. None of the patients required two-person mask ventilation or where unable to be mask ventilated. By using this definition they may have increased the frequency of observed events, possibly skewing the results.

 

Over a third of the anesthesia providers changed their anesthetic plan after evaluating the obese child. This change resulted in a higher frequency of intravenous induction and intubation in obese children in all age ranges. While the provider may have felt intubation was clinically indicated, I think it may have resulted in a significantly higher rate of bronchospasm and secondary oxygen desaturation. This in fact may have skewed their results. I suspect if the type of airway device had been controlled for statistically the associations would not have been that large. I suspect that in the United States many anesthesia providers would have been more comfortable placing an LMA in many of these obese children (especially in those with asthma) for these procedures. With the availability of newer ventilation modes (SIMV and PSV) I feel much more comfortable placing LMAs in obese patients.

 

Despite these limitations, this study has important implications for practice because it reminds us that obese pediatric patients are at greater risk for respiratory adverse events. I think if faced with an obese asthmatic pediatric patient, the anesthesia provider needs to weigh the risks and benefits of intubation versus LMA placement to avoid bronchospasm. If intubation is indicated, the anesthesia provider should ensure the child is at a sufficient depth at the time of intubation, and utilize techniques on emergence to minimize the risk of bronchospasm.

Dennis Spence, PhD, CRNA


The views expressed in this article are those of the author and do not reflect official policy or position of the Department of the Navy, the Department of Defense, the Uniformed Services University of the Health Sciences, or the United States Government.


© Copyright 2011 Anesthesia Abstracts · Volume 5 Number 3, March 31, 2011