ISSN NUMBER: 1938-7172
Issue 4.9 VOLUME 4 | NUMBER 9

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

Assistant Editor
Jessica Floyd, BS

A Publication of Lifelong Learning, LLC © Copyright 2010

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


Cardiovascular
Association of the pattern of use of perioperative β-blockade and postoperative mortality

Anesthesiology 2010,113:794-805

Wallace AW, Selwyn A, Cason BA


Abstract

Purpose The purpose of this study was to evaluate the association between the pattern of perioperative β-blocker administration and postoperative mortality. Beta Blocker administration was based upon the Perioperative Cardiac Risk Reduction protocol.

Background Multiple studies have demonstrated that perioperative β-blockade reduces 30-day and 2-year mortality in patients at high risk for myocardial ischemia and infarction.  At the San Francisco Veterans Affairs Medical Center, a protocol, called the Perioperative Cardiac Risk Reduction Therapy (PCRRT), was developed based upon these studies. Anesthesia providers in the preoperative clinic would start high risk patients (Table 1) on perioperative β-blockers when appropriate, or continue β-blockers if the patient was already on them. However, after publication of the PeriOperarative Ischemia Evaluation trial (POISE trial), which found increased bradycardia, hypotensive strokes, and all-cause mortality in patients treated with larger doses of β-blockade, the American Heart Association recommended more conservative guidelines for perioperative β-blockade. 

Methodology This study was an epidemiological evaluation of the safety, efficacy, and patterns of the PCRRT protocol at a single institution over a 12-year period. Beta-blocker use patterns were classified into one of four groups: 

(1) None – received no β-blockade before, during or after surgery.

(2) Addition – no β-blockade preoperatively but received at least one dose after surgery.

(3) Withdrawal – were receiving β-blockers preoperatively, but did not receive at least a single dose after surgery.

(4) Continuous – taking β-blockers preoperatively and received at least one dose after surgery.

Appropriate use of β-blockers was defined as the number of patients actually taking β-blockers based on PCRRT protocol, divided by the total divided by all high risk patients. PCRRT protocol was in wide, but non-mandatory, use at this hospital. Logistic regression, survival analysis, and propensity analysis was used to evaluate associations with 30-day and 1-year mortality rates based on the four groups. Clonidine was added to the protocol in 2004; its use was limited and data on its efficacy were not included in the results.

Table 1. Perioperative Cardiac Risk Reduction Protocol

High Risk patient 

Β-blockade Protocol

Refer to Cardiology 

  •  Hx of CAD or PVD
  •  At least of two risk factors for CAD:
  •  Age>60
  •  Hypertension
  •  Diabetes
  •  Cholesterol >240 mg/dl
  •  Smoker

If high risk & no contraindications initiate β-blockade.

  •  Start Atenolol 25 mg PO QD if HR>60 & SBP>120 mmHg. Titrate to effect.
  •  Atenolol of metoprolol IV on day of surgery if target heart rate not achieved (55-60 bpm).
  •  Increase to 100 mg QD if SBP >100 mmHg and HR>65 bpm.
  •  Dosage is 50 mg QD if HR between 55-65 BPM.
  • Hold if HR<50 or SBP<100 mmHg.
  • If unable to take PO use IV metoprolol 5 mg IV Q6 H.
  • Continue for β-blockade for at least 30 days postoperatively.
  • If unable to take β-blockers clonidine may be used.
  • Aortic stenosis
  • CHF
  • Unstable angina
  • New-onset CP
  • Change in angina pattern
  • Angina without medical therapy
  • Intra-coronary stent on platelet inhibitor

Note. See www.betablockerprotocol.com for more information.

Result A total of 38,779 surgical procedures on 20,937 different patients were performed over 12 years. The majority of the patients were men with a mean age of 63 ± 13 years. The most common outpatient β-blocker used was atenolol (54%) with a median dose of 50 mg, whereas the most common inpatient drug was metoprolol (75%) with a median dose of 25 mg. The percentage of β-blocker use in all surgical patients was: (1) None 48%, (2) Addition 15%, (3) Withdrawal 5%, and (4) Continuous 33%. Thirty percent of high risk patients with two or more risk factors received no β-blockers.

Based on the PCRRT protocol, 21,272 out of 38,779 patients (55%) qualified for perioperative β-blockade. The 30-day and 1-year mortality analysis completed on 13,629 patients who underwent high risk procedures are listed in Table 2. The Addition or Continuous use of β-blockers was associated with lower odds of dying at 30-days and 1-year when compared to the None group. However, when β-blockers were withdrawn, the odds of dying at 30 days was almost four times greater. Survival analysis of 6,731 high risk inpatients indicated that the Addition or Continuous use of β-blockers was superior to no use (None group). Finally, compared to the None group, Withdrawal of β-blockers was associated with increased mortality.

Table 2.  Patient Cardiac Risk Reduction Therapy and 30-day and 1-year Mortality 

Group

30-day mortality OR

1-year mortality OR

Addition

 0.52; 95% CI, 0.33 to 0.83

0.64; 95% CI, 0.51 to 0.79

Continuous

 0.68; 95% CI, 0.47 to 0.98

0.82; 95% CI, 0.67 to 1.0

Withdrawal

3.93; 95% CI, 2.57 to 6.01

1.96; 95% CI, 1.49 to 2.58*

Note. OR = odds ratio. Odds of mortality at 30-days and 1-year when compared to the None group. OR > 1 indicates increased risk and OR < 1 indicates less risk. All results P < 0.05. *P = 0.05. 

Between 1996 and 2008 there was a significant increase in the percentage of patients having Continuous β-blocker use and a decrease in the number who received None (P < 0.0001). There was also an increase in the percentage of patients in the Withdrawal group (P < 0.0001). No significant change in the Addition of β-blockers was noted over the 12 year period (P = 0.60). Over the 12 year study period, 30-day mortality decreased from approximately 4.5% to 0.5% (P = 0.0001) and 1-year mortality from approximately 16% to 4% (P = 0.00003).

Conclusion At the San Francisco Veterans Administration Medical Center, the PCRRT protocol was associated with a reduction in the 30-day and 1-year mortality rates in high-risk inpatients. Withdrawal of β-blockade therapy was associated with the highest mortality.

 

Comment

The perioperative use of β-blockers has been a hot topic in anesthesia for a number of years. Initial studies showed a benefit, whereas later studies, such as the PeriOperarative Ischemia Evaluation trial study (POISE trial) showed a reduction in myocardial infarction and cardiology consultations, but at the cost of increased bradycardia, hypotension, stroke, and all-cause mortality. The difference between the POISE trial and this current PCRRT study was that the POISE trial started patients on metoprolol XL 400 mg on the day of surgery followed by 200 mg a day. In the PCRRT study patients were started at 25 mg of atenolol QD. Thus it may be that lower initial doses that were titrated to achieve a clinical effect were safer and more efficacious than high dose β-blocker therapy.

The most important finding of this study was that withdrawal of β-blockers during the perioperative period is BAD, especially in patients at high risk for perioperative myocardial infarction. This is even more significant when you consider the mortality rates associated with perioperative myocardial infarction are rather high. Therefore, I think the take home message from this study is to ensure that high risk patients continue taking their β-blockers throughout the perioperative period. Additionally, as Dr Wallace and colleagues suggest, those at high risk not on β-blockers should be started on them.

Anesthesia providers should evaluate the preoperative screening process at their facilities and ensure that protocols and processes are in place to make sure patients on β-blockers are continued, or if needed started on them. I think this study was an excellent demonstration of Evidence-Based Practice. The investigators saw a problem, they developed a protocol to fix the problem, included stakeholders, continually educated, and evaluated the results. For those of you thinking of working on your Doctorate of Nursing Practice (DNP), I think the PCRRT is an excellent protocol that a DNP student could implement for their project. 

There are some limitations that should be pointed out. First, this was a retrospective study, and thus causation cannot be determined. As the investigators pointed out, the PCRRT protocol was not mandatory, but highly encouraged to be used. Also the definitions used for the categories grouped patients based on whether or not they took a single dose. I believe it was assumed that many patients in the continuous or addition categories took more than one dose. The investigators did use a very sophisticated statistical analysis technique, propensity score matching, which helped compensate for the limitations with a retrospective design (i.e., lack of randomization) by attempting to provide unbiased estimation of treatment-effects. Finally, the mortality results are on high risk inpatients, who where predominately male. The VA administration on the whole takes care of higher acuity surgical patients who are probably commonly at risk for myocardial infarction. They do not have a large female population, though I believe the results can easily, and should, be applied to women. The results should also be applied to patients undergoing outpatient surgical procedures, because patients experience just as much stress with outpatient surgery as they do with larger inpatient procedures. Despite these limitations, this is an excellent study that providers can directly apply to improve clinical practice.

Dennis Spence, PhD, CRNA


Readers are encourage to visit www.betablockerprotocol.com to get more information on the PCRRT.

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, Department of Defense, the Uniformed Services University of the Health Sciences, or the United States Government.


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010




General
Effect of a 19-item surgical safety checklist during urgent operations in a global patient population

Ann Surg 2010;215:976-980

Weiser TG, Haynes AB, Dziekan G, Berry WR, Lipsitz SR, Gawande AA


Abstract

Purpose The purpose of this study was to evaluate the effect of implementing a 19-item surgical checklist developed by the World Health Organization (WHO) “Safe Surgery Saves Lives” Program on adherence to basic standards of care and the rate of complications and death following urgent surgery.

Background Urgent surgical procedures are associated with increased risk of complications and death. Recent investigations have demonstrated that the WHO 19-item surgical checklist was associated with a 33% decrease in complications across all types of non-cardiac surgical procedures in a global patient population. However, it is unclear if the checklist would result in delays of therapeutic care or interrupt workflow in urgent surgical procedures.  

Methodology This was a prospective pre- post-intervention investigation of 1,750 consecutively enrolled patients aged 16 or older undergoing urgent, non-cardiac surgery at 8 diverse hospitals around the world. The hospitals participated in the “Safe Surgery Saves Lives” pilot program to evaluate the effect of implementation of the 19-item WHO Surgical Checklist (Table 1). The hospital types included: (1) public, urban, (2) mission, urban, and (3) district, rural hospitals in high to low income countries. Urgent operations were defined as an operation required within 24 hours of assessment. Process adherence with the surgical checklist was defined as completion of a subset of 6 safety measures from the surgical checklist. An adherence score was based on a composite of these 6 items. The primary outcome was the occurrence of any major complication, including death, within 30 days of surgery. Definitions of complications were based upon the American College of Surgeons’ National Surgical Quality Improvement Program.

Table 1. 19-Item WHO Surgical Safety Checklist

Sign-In (before induction)

Time Out (before incision)

Sign Out (before patient leaves OR

  1. Confirm identity, site, procedure and consent with patient.
  1. Site marked.
  2. Anesthesia safety check completed.
  3. Pulse oximeter on and functioning.
  4. Allergies verified.
  5. Difficult Airway/Aspiration Risk? If yes equipment available.
  6. Risk of >500 mL blood loss? If yes adequate IV access and fluids planned (2 large bore IVs or central line).
  1. Team members introduce themselves.
  2. Surgeon, anesthesia provider, and nurse confirm patient, site and procedure.

Anticipated critical events reviewed by:

  1. Surgeon.
  2. Anesthesia team reviews patient-specific concerns.
  3. Nurses confirm sterility and equipment issues or concerns.
  4. Antibiotic prophylaxis given within last 60 minutes?
  5. Essential imaging displayed?

Nurse confirms with team:

15. Name of procedure.

16. Instrument, sponge and needle count are correct.

17. Specimen labeling

18. Any equipment problems to be addressed?

19. Surgeon, anesthesia provider, and nurse review key postoperative concerns and management issues.

Note. Process adherence with the surgical checklist was defined as completion of a subset of 6 safety measures from the surgical checklist (these items are in bold).

Result Pre-intervention n = 842 patients underwent urgent operations without use of the WHO checklist. Post-intervention n = 908 patients had surgery after implementation of the surgical checklist. There were no significant differences in demographics between patients before or after implementation of the intervention, with the exception of more patients undergoing urgent colorectal surgery post-intervention (pre: 15.6% vs. post: 22.2%, P <0.0001) and more urological and gynecological procedures in the pre-intervention phase (pre: 3.9% vs. 3.4%, P = 0.025). Over one third of all procedures were Obstetric surgical procedures. 

The overall complication rate at baseline was 18.4% (n = 151 cases) compared to 11.7% after checklist implementation (P = 0.0001). Mortality rate decreased from 3.7% to 1.4% (P = 0.0067). Surgical site infection decreased from 11.2% to 6.6% (P = 0.0008). Estimated Blood Loss greater than 500 mL decreased from 20.2% to 13.2% (P <0.0001). Adherence to the 6 measured safety steps increased from 18.6% to 50.7% (P<0.0001; Figure 1).

checklist results

Conclusion Use of the WHO 19-item surgical checklist was associated with over a one-third reduction in complications in patients undergoing urgent, non-cardiac surgery in diverse hospitals around the world. The surgical checklist was feasible to implement during urgent operations.

 

Comment

In the recent years there has been an increase focus, on a global scale, to improve safety and decrease complications during surgery. Atul Gawande and his research group from the World Health Organization demonstrated in this study that the use of a simple checklist could significantly improve outcomes after surgery in a diverse group of hospitals from around the world. I must admit a year or so ago when my facility started implementing the WHO checklist, I was a little skeptical. I think many of my colleagues felt the same way. However, overtime I have seen how the use of the checklist has helped prevent complications and “near-misses”. After reading Dr Gawande’s book, The Checklist Manifesto, and this study I am now convinced of the importance of implementing the surgical checklist in all procedures. 

During urgent (and sometimes routine) cases it is easy to miss a critical step because we are focused on providing care to the patient. However the aviation community has consistently demonstrated that the use of checklists can avoid accidents. I believe it is important that we try to take the time, just as pilots do, regardless of the urgency of the procedure, to go through the checklist. It should not be limited to procedures in the operating room, but in all areas. For example, taking the time to go through the checklist and verifying you have the right patient and side prior to placing a peripheral nerve block could prevent a wrong site procedure (i.e., blocking the wrong leg). Communication and team work are critical to what we do, and I think using this checklist is a first step to improving the care we provide to our patients. 

Dennis Spence, PhD, CRNA


For readers who would like to learn more about checklists, how they have led to improvements in multiple disciplines and settings, and on how the WHO checklist was developed should read Dr Atul Gawande’s book, The Checklist Manifesto, How to Get Things Right. 

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, Department of Defense or the United States Government.


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010




Obstetric Anesthesia
Oral intake during labor: a review of the evidence

Am J Matern Child Nurs 2010;35:197-203

Sharts-Hopko NC


Abstract

Purpose The purpose of this article was to review the evidence concerning oral intake during active labor in low risk patients.

Background Curtis Mendelson authored a study in 1946 evaluating the incidence of pulmonary aspiration in labor and recommended that women fast throughout labor. This recommendation was widely adopted even though the study concluded that the incidence of aspiration was very rare. In addition, “twilight” and general anesthesia was commonplace during labor in the 1940’s. Over the years, regional anesthesia greatly replaced other forms of pain management during labor, and pulmonary aspiration has become so rare that randomized clinical trials to evaluate the incidence of aspiration based on oral intake is no longer feasible. However, a question still persists about the risk and benefit of oral intake during labor.

Methodology The article presented current recommendations on oral intake during labor from several health care organizations. In addition, it addressed important aspects of patient care including energy needs in labor, ketosis, hyponatremia, maternal stress, vomiting, and obstetric outcome.

Result The following table represents the recommendations of the listed organizations.

 

Organization

Recommendation

American Society of Anesthesiologists (ASA)

Small amounts of clear liquids up to 2 hours before anesthesia for women with no complications

American Congress of Obstetricians and Gynecologists (ACOG)

Clear liquids for women at low risk for pulmonary aspiration

American College of Nurse Midwives

Self-determination regarding oral intake encouraged for women at low risk of pulmonary aspiration

World Health Organization (WHO)

Noninterference with laboring women’s desire for food or liquid without cause

 


There are a number of other issues that need to be considered when evaluating the impact of oral intake policies.

Energy needs during labor: The American College of Sports Medicine endorses the use of high carbohydrate intake during exercise to reduce fatigue. It is evident that woman in labor may require similar nutritional supplementation in order to prevent fatigue.

Ketosis: Pregnant women may be prone to ketosis because of the demands of labor, fetal growth, and hormonal changes.

Hyponatremia: Exclusive use of water for oral intake during labor can lead to hyponatremia and complicate labor. Studies have shown that intake of between 4 and 10 liters of water or fruit juice have created symptoms of hyponatremia in laboring women. Hyponatremia was also associated with prolonged labor, higher incidence of instrument deliveries, and emergency cesarean section. It is recommended that hypotonic fluids be limited to less than 2 liters during labor.

Maternal Stress: Studies have indicated that the limitation of oral intake during labor can cause moderate to intense psychological stress in the majority of woman questioned. It is apparent that limited oral intake can impact patient satisfaction and psychological wellbeing.

Vomiting: The incidence of vomiting is found to be more prevalent with solid intake than with fluid intake. The volume of intake does not appear to impact the incidence of vomiting. None of the women studied had a poor outcome. In addition to vomiting, the ingestion of solid foods during labor was found to prolong labor, but no other adverse outcomes were noted.

Obstetric outcome: Several studies concluded that the type of oral intake, solid or liquid, did not have an adverse impact on the outcome of labor with the exception of the previously noted prolongation of labor in the solid intake group.

Conclusion Other than the possibility of hyponatremia with hypotonic fluid intake, and the prolongation of labor with solid food intake, the type and quantity of oral intake during labor does not appear to have a negative impact. Because gastric emptying is lowered during labor, foods high in fat may be a poor choice. Woman with comorbidities, chronic disease, preeclampsia, neurologic disorders, gastric problems, obesity, or factors associated with difficult airways should limit their intake to clear liquids during labor. When policies about oral intake are relaxed, woman should be informed of the potential risks of solid intake and a plan should be in place to evaluate patient outcome.

 

Comment

It appeared that throughout this article the author was advocating for relaxed oral intake policies even though little compelling evidence was provided that the risks of solid food intake during labor was less than the benefit. Throughout the studies evaluated, there were conclusions pointing to problems with solid food intake during active labor.  Those problems included an increase incidence of vomiting and prolongation of labor. I can certainly understand the risk of providing large amounts of hypotonic fluids during labor, and the impact lack of carbohydrate intake can have on energy levels during the high metabolic demands created with active labor; but those risks can be minimized and the energy needs met with high carbohydrate fluid intake. Kubli, et al (2002) evaluated the use of “Sport Drinks” during labor.  They found that even small caloric intake of 47 kcal/hr can prevent ketosis in laboring woman.

I understand that there is a negative psychological impact when solids are withheld from laboring woman, and that the risk of aspiration is very small, but any potential problem that is as serious as aspiration pneumonia should be minimized. In my opinion, it continues to be prudent to withhold solids from women in active labor and offer them carbohydrate containing liquids instead, especially if a surgical intervention is possible.  With the cesarean section rate in the United States climbing above 35%, I would say that the risk of a surgical intervention is present in every laboring patient.  



Steven R Wooden, MS, CRNA


Kubli, M., Scrutton, M. J., Seed, P. T., & O'Sullivan, G. An evaluation of isotonic "sport drinks" during labor. Anesth Analg 2002;94:404-408


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010





Prevention of postdural puncture headache after accidental dural puncture: a quantitative systematic review

Br J Anaesth 2010;105:255-6

Apfel CC, Saxena A, Cakmakkaya OS, Gaiser R, George E, Radke O


Abstract

Purpose This was a systematic review and meta-analysis comparing the efficacy of preventive treatments after accidental dural puncture.

Background The incidence of postdural puncture headache (PDPH) is >50% after accidental dural puncture with a Tuohy needle. PDPH is a significant source of morbidity in postpartum mothers, and depending on the severity of the headache, may limit a mother’s ability to care for her newborn. Conservative measures are typically ineffective (bed-rest, hydration); therefore invasive measures such as prophylactic blood patch, epidural saline bolus, intrathecal catheter placement, and epidural morphine injection have been investigated as preventive measures. However, efficacy of these various measures has been mixed, and there is no clear consensus of the best prophylactic measure to prevent PDPH after accidental dural puncture.

Methodology The investigators performed a systematic review and meta-analysis of studies evaluating the efficacy of measures to prevent PDPH after accidental dural puncture. Inclusion criteria of randomized and non-randomized controlled trials were based on the Cochrane Handbook for Systematic Reviews. Studies with intentional lumbar puncture and no control group were excluded. The primary outcome was the incidence of PDPH. Results were presented as relative risks (RR) with 95% confidence intervals (CI).

Result A total of 17 out of 29 identified studies with n = 1,264 patients were included in the review. All but one study evaluated interventions in postpartum patients. Five intervention groups were identified: one study on epidural morphine, nine on prophylactic epidural blood patch (PEBP), three with epidural saline, one with intrathecal saline, and six with intrathecal catheter placement. The majority of the studies were non-randomized controlled trials. Only the study on epidural morphine and four of nine studies evaluating prophylactic epidural blood patch were randomized controlled trials.

In the four Randomized Controlled Trials evaluating PEBP, the relative risk for PDPH was 0.32 (95% CI: 0.10, 1.03) while in five non-Randomized Controlled Trials the relative risk of PDPH was 0.48 (95% CI: 0.23, 0.99). Prophylactic epidural morphine injection after accidental dural puncture was associated with relative risk for headache of 0.25 (0.08, 0.78), though the results were based on a small sample size (n = 50). None of the other interventions, all non-Randomized Controlled Trials, were significantly associated with a reduced risk of PDPH (Table 1). There was significant heterogeneity between studies (variation in study outcome) and publication bias towards small non-Randomized Controlled Trials showing positive results.

Table 1. Results

Intervention

RR (95% CI)

Prophylactic epidural blood patch (non-Randomized)

0.48 (0.23, 0.99)

Prophylactic epidural blood patch (Randomized)

0.32 (0.10, 1.03)

Epidural morphine (Randomized)

0.25 (0.08, 0.78)

Epidural saline (non-Randomized)

0.65 (0.40, 1.05)

Intrathecal saline (non-Randomized)

0.51 (0.26, 1.03)

Short term intrathecal catheter placement (non-Randomized)

0.88 (0.68, 1.14)

Long-term intrathecal catheter placement >24 h (non-Randomized)

0.21 (0.02, 2.65)

A RR < 1 indicates a potential benefit of the intervention; statistical significance was assumed if the 95% CI did not include the number 1.

Short-term intrathecal catheter placement: catheter removed after delivery or left in situ for at least 2 h.

Conclusion All interventions showed some efficacy in preventing PDPH; however the heterogeneity of results and publication bias make it difficult to make firm recommendations. Large, multi-center Randomized Controlled Trials are needed to determine which interventions are most efficacious.

 

Comment

Over the years, numerous prophylactic interventions have been attempted to reduce the risk of PDPH. Unfortunately none have been found to be the “magic bullet” for preventing development of a PDPH in peripartum women. One of the reasons is that the incidence of accidental dural puncture is approximately 1%, with between 50-88%1 of parturients with a dural puncture from a Tuohy needle developing a PDPH. The relative rare occurrence makes it difficult to study, and you combine this with low quality studies on prophylactic interventions (i.e., non-Randomized Controlled Trials) and it is easy to see how the current review was unable to make firm recommendations. The authors suggest large, multi-center studies are needed; however these would be very expensive and unlikely to be done.

So where does that leave us?

First I think it is important to inform patients that a PDPH is a potential risk, and if an accidental dural puncture occurs to be forthright and explain to the patient what the likelihood of developing a PDPH is and what the symptoms are. I tend to favor closely following patients then offering them a therapeutic blood patch2, after ruling out other potential causes of headache, if they develop signs or symptoms of a moderate to severe PDPH. Many times, it is preferable to offer the blood patch prior to discharge, though mechanisms should be in place to ensure patients can return for evaluation and treatment. Conservative therapies such as bed-rest1 and caffeine1,3 are largely ineffective, and the former is an unrealistic expectation for a new mother.

If providers choose to use a preventive therapy, they should weigh the risks and benefits. For example if the patient was a morbidly obese parturient with a difficult airway, and it was a difficult epidural, then I might consider placing an intrathecal catheter, more so for labor analgesia and the ability to obtain a surgical block if needed, than prevention of a PDPH. I then might consider leaving the catheter in for at least the short-term to possibly decrease the risk of a PDPH. However, the catheter should be clearly labeled as an intrathecal catheter to ensure that an epidural bolus dose of local anesthetic is not administered. As for prophylactic blood patches, authors of a recent Cochrane review article concluded that there were too few well designed clinical trials, and thus they could not recommend this intervention.2 I believe clinically many anesthesia providers have stopped performing prophylactic blood patches because they were found to be ineffective and an unnecessary risk. Epidural morphine administration for preventing a PDPH is probably not routinely done in the United States, and given the potential side effects (i.e., nausea, pruritis, and urinary retention) I would not use it solely for prevention of a headache. 

Dennis Spence, PhD, CRNA


1. Sprigge JS, Harper SJ. Accidental dural puncture and post dural puncture headache in obstetric anesthesia: presentation and management: a 23-year survey in a district general hospital. Anaesthesia 2008;63:36-43.
2. Boonmak P, Boonmak S. Epidural blood patching for preventing and treating post-dural puncture headache. Cochrane Database of Systematic Reviews 2010, 1: CD001791. 
3. Halker RB et al. Caffeine for the prevention and treatment of postdural puncture headache: debunking the myth. Neurologist 2007;5:323-7


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, Department of Defense or the United States Government.


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010




Policy, Process, & Economics
Slowing down to stay out of trouble in the operating room: remaining attentive in automaticity

Acad Med 2010;85:1571-1577

Moulton C, Regehr G, Lingard L, Merritt C, MacRae H


Abstract

Purpose The purpose of this study was to observe and describe the phenomenon of “slowing down.”

Background As experts gain experience and knowledge, their behavior takes on a pattern of automaticity during routine performance. Experts cannot stay in this routine mode all the time; they must be able to transition to a more effortful mode when the situation requires it. This more effortful mode of increased cognitive attention during times of uncertainty is termed “slowing down” and has been described in the behavior of surgeons. When surgeons slow down their speed of work does not necessarily decrease, although it may. Previous studies of slowing down in surgeons were drawn primarily from data obtained from interviews. This study was designed to further describe slowing down and include observations of this phenomenon in intraoperative environments.

Methodology In order to keep the context of the study about expert performance, surgeons for this study were recruited based on their reputations for excellent clinical judgment. Researchers interviewed 28 surgeons from nine different specialties during phase 1 of this study. Interviews focused on the surgeon’s experiences with, and perceptions of, slowing down. During phase 2, the behavior of five different surgeons was observed for overt manifestations of slowing down. The resulting data were analyzed using a grounded theory methodology, which is a type of qualitative research that is used to generate descriptions and explanations of social phenomenon. 

Result The research team analyzed interview transcripts and operating room observations for repetitive patterns that indicated emerging themes. This analysis resulted in the identification of four themes associated with slowing down. Stopping was the most extreme manifestation, as surgeons literally called for a momentary halt of the operative procedure. The second theme identified with slowing down was removing distractions, when surgeons would ask for quiet. A more subtle manifestation of slowing down was focusing more intently, when surgeons would withdraw from conversations, while allowing others to continue talking. The fourth theme identified was fine-tuning. This was the most subtle manifestation of slowing down, occurring on a moment to moment basis. 

When surgeons allow their routine behaviors to become complacent, they risk failing to recognize cues that indicate slowing down is required. The researchers called this drifting. Drifting lacks the attentive focus required when fine tuning. While fine tuning is used to stay out of trouble, drifting can often lead to adverse effects.

Conclusion Expert surgeons can multi-task as they operate during routine situations. While they are engaged in conversation they are also fine tuning in order to recognize situations that require more focused attention. When such cues are recognized, they increase their capacity for attention by ignoring distracting stimuli and focusing more intently. If this does not result in the level of attention required, they remove the distractions completely by asking the entire room to be quiet. Slowing down resulting in the maximum attention available to surgeons occurred when operations came to a complete halt, either emergently or in deliberate preparation for a challenging part of the procedure. It may be that surgeons do not allow their behavior to be totally automatic. Instead they may stay in a constant state of attentive automaticity and fine tuning in order to avoid the risky state of inattentive automaticity and drifting.

While the more obvious forms of slowing down are easily noticeable, the more subtle slowing down moments are less easily observed. Consequently, other members of the operative team may be unaware that a moment calls for increased attention and mental focus. Increased recognition of slowing down, particularly in its more subtle manifestations, would increase team effectiveness.

Trainees could benefit from specific instruction to learn how to recognize when the surgeon is experiencing a slowing down moment, in order to respond appropriately. Additionally, trainees could benefit from learning how slowing down affects their own performance. Trainees need more focused attention than experienced clinicians, and need to learn how to slow down when appropriate as they develop their own expertise.

 

Comment

Much of the research that applies to our anesthesia practice provides us with concrete data. It is difficult to generate concrete data when the subject of the research is human behavior. And yet, human behavior does have implications for our practice. After all, we are human beings, working in teams with other human beings, in order to provide care to patients, who are also human beings. The behavior of health care providers, and their interactions with each other has an effect on the resulting care that is provided. The research design and methods that were used in this study are consistent with its focus on human behavior.

In this study, data were collected from 33 surgeons, a sample size consistent with the intensive nature of data collection in this method of research. Including multiple specialties contributed to the strength of this study, but it still cannot be known if the same themes would emerge in a different group of surgeons. In fact, it is not the aim of this type of research to produce results that are generalizable. Instead, the results are used to develop proposed explanations of how we behave and interact. Subsequent research is needed to test if these explanations hold true.  

Many experienced nurse anesthetists are probably not surprised by this research. When we work with the same surgeons case after case, we get to know their behavioral patterns. We can tell when they feel like social conversation, and when it is better to be quiet and let them concentrate. This research may support that these are not isolated incidents, and these same transitions occur commonly. This research proposes a more structured description of what we have learned only through hit and miss, trial and error.

This study prompts us to be even more observant of our surgeons during cases. If we can learn to recognize even the more subtle slowing down moments, we may learn of surgical problems earlier, which may allow us to improve our anesthetic management. We can help those new to the operating room environment, including our nurse anesthesia students, learn to recognize the signs that surgeons are “slowing down.”

There is value in applying these findings to our own practice. We stay in a state of attentive automaticity, remaining vigilant to the cues that signal us that fine tuning is required to stay out of trouble. Drifting into inattentive automaticity is dangerous in anesthesia, because it can lead to missing a cue to an impending adverse event. It seems likely that future research may show that anesthesia experts follow a pattern similar to the surgeons in this study.


Cassy Taylor, DNP, DMP, CRNA


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010




Respiration & Ventilation
Positive end-expiratory pressure (peep) during anaesthesia for the prevention of mortality and postoperative pulmonary complications

Cochrane Database Syst Rev 2010 Sep 8: CD007922

Imberger G, McIlroy D, Pace NL, Wetterslev J, Brok J, Møller AM


Abstract

Purpose The purpose of this meta-analysis was to assess the benefits and harms of intraoperative PEEP on postoperative mortality and pulmonary outcomes in adult surgical patients.

Background Pulmonary complications, such as atelectasis and pneumonia, are among the most common complications occurring after general anesthesia. Atelectasis contributes to decreased functional residual capacity (FRC), pulmonary shunting, decreased arterial oxygenation, and impaired ability to clear secretions. General anesthesia is known to cause atelectasis and decreased functional residual capacity (FRC), especially in patients who are obese. 

Positive end-expiratory pressure (PEEP) is an intervention that exerts positive pressure at the end of each exhalation during artificial ventilation. PEEP maintains the patency of alveoli, prevents atelectasis and increases functional residual capacity (FRC). PEEP has been used to effectively offset general anesthesia induced atelectasis and improve intraoperative oxygenation. What is less clear is the effect of intraoperative PEEP on postoperative complications and outcomes of patients following general anesthesia.

Methodology Standard strategies developed by the Cochrane Collaboration for searching multiple international databases were applied to identify studies for this meta-analysis. Only previously conducted experimental, randomized clinical trials were included. The studies involved patients over the age of 16 receiving general anesthesia for any surgical procedure, whose airways were maintained with laryngeal masks or endotracheal tubes, and did or did not receive muscle relaxants. Patients who received any level of PEEP maintained from induction to emergence were considered the intervention group. Control group patients received zero PEEP. 

Outcome measures examined were mortality, respiratory failure, oxygen efficiency (measured by PaO2/FiO2), mechanical ventilatory support, pneumonia, CT identified atelectasis, pneumothorax, pneumomediastinum, subcutaneous emphysema, unstable angina, myocardial infarction, left ventricular failure, intensive care unit admission, post anesthesia care unit and hospital length of stay. After potential studies were inspected for fit into the inclusion criteria, eight trials of 330 patients were pooled together for the meta-analysis.  

Result The pooled data contained zero or very small numbers of many of the postoperative outcomes, resulting in insufficient evidence to support or refute the effect of intraoperative PEEP on most of the variables of interest.

The intraoperative PEEP group had statistically significant differences for two of the research variables. Oxygen uptake efficiency, measured by PaO2/FiO2, increased an average of 22.98 torr on postoperative day 1. Pooled data from 41 patients demonstrated significantly higher oxygen uptake efficiency only on postoperative day 1. Oxygen uptake efficiency differences at later time points did not achieve statistical significance. Atelectasis size, graded on a 6 point scale, was smaller while in PACU (standardized mean difference of 1.2).

Conclusion The reduction in postoperative atelectasis in patients who received intraoperative PEEP was noteable. However, since the data were only derived from 88 patients, it may be premature to take substantial meaning from the difference. It is unclear how much of a reduction in atelectasis would be required to achieve clinically significant patient benefits.

It is unknown whether intraoperative PEEP increased oxygen uptake efficiency, albeit for only the first postoperative day, or if this result was a chance finding. Furthermore, it is questionable whether or not the increase in oxygen uptake efficiency that was observed would result in clinically significant patient benefits.

This meta-analysis yielded insufficient evidence to demonstrate any postoperative benefits or harms of intraoperative PEEP.

 

Comment

The Cochrane Collaboration is an international group that generates outcome studies intended to guide best practice decisions. This meta-analysis did not show benefit to the widespread application of PEEP; perhaps because there is no benefit or perhaps because their sample included too few patients who experienced respiratory complications.

Nurse anesthetists must make case by case decisions about whether to add PEEP to their patients’ ventilation during general anesthesia. We make such decisions by comparing the benefits to the risks. PEEP is used for its benefits of decreased pulmonary shunt and increased arterial oxygenation. But it carries the risk of increased intrathoracic pressure, potential barotrauma, decreased venous return, decreased stroke volume, and hemodynamic instability. Obviously, if the addition of PEEP keeps a patient from developing hypoxemia during their anesthetic, the decision is made easily. But if the patient’s condition is such that PEEP is not needed for intraoperative oxygenation, should we still consider adding it to the patient’s ventilation? If this meta-analysis had demonstrated that widespread use of PEEP could lead to patient benefit lasting into the postoperative period, PEEP might be worth the potentially negative intraoperative effects.

Atelectasis and pneumonia are among the most common of postoperative complications following general anesthesia, especially those who have preexisting lung disease. It makes theoretical sense that PEEP could reduce the risk for these complications. However, the available evidence doesn’t support this idea. With no clear evidence of postoperative benefit in patients who receive PEEP intraoperatively, the benefits of PEEp probably do not outweigh the risks in the context of routine use. PEEP should probably be reserved for patients in whom it improves intraoperative oxygenation or where there is reason to believe it will reduce the risk of postoperative respiratory complications in that specific patient.


Cassy Taylor, DNP, DMP, CRNA


© Copyright 2010 Anesthesia Abstracts · Volume 4 Number 9, September 30, 2010