ISSN NUMBER: 1938-7172
Issue 12.6 VOLUME 12 | NUMBER 6

Editor:
Michael A. Fiedler, PhD, CRNA

Contributing Editors:
Mary A Golinski, PhD, CRNA
Dennis Spence, PhD, CRNA

Assistant Editor
Jessica Floyd, BS

A Publication of Lifelong Learning, LLC © Copyright 2018

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
Digital palpation of the pilot balloon vs. continuous manometry for controlling the intracuff pressure in laryngeal mask airways
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OBSTETRIC ANESTHESIA
Epidemiology of cardiac arrest during hospitalization for delivery in Canada: a nationwide study
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REGIONAL ANESTHESIA
Anesthesia technique and mortality after total hip or knee arthroplasty: a retrospective, propensity score-matched cohort study
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None of the editors or contributors have any real or potential conflicts of interest to disclose.
 
This program has been prior approved by the American Association of Nurse Anesthetists for 20 Class A CE credits; Code Number 1035464; Expiration Date 10/31/2020.

Airway
Digital palpation of the pilot balloon vs. continuous manometry for controlling the intracuff pressure in laryngeal mask airways

Anaesthesia 2016;71:1169-76

DOI: 10.1111/anae.13566

Hensel M, Güldenpfennig T, Schmidt A, Krumm M, Kerner T, Kox WJ


Abstract

 

Purpose   The purpose of this study was to compare digital palpation to continuous manometry for regulating laryngeal mask airway (LMA) cuff pressures.

 

Background   Overinflation of LMAs can contribute to pharyngolaryngeal complications such as sore throat, dysphonia, and dysphagia. Several investigations have demonstrated that use of manometry results in decreased LMA cuff pressures and a reduction in pharyngolaryngeal complications. Despite this, many providers still use digital palpation of the pilot balloon to estimate, and guide adjustment of, LMA cuff pressure.

 

Methodology   This was a prospective, randomized, double-blind, controlled study of 243 consecutive patients undergoing surgery that required LMA placement. Patients were randomized to either digital palpation by the anesthesia provider or continuous manometry. A standardized anesthetic and postoperative analgesia regimen were used for all patients. After LMA placement, all patients were placed on pressure-controlled ventilation with maximum pressures set at 20 cm H20. An LMA SureSeal PreCurved SU (Teleflex, Westmeath, UK) was used. Women <50 kg had a size 3 placed, women >50 kg a size 4, and men had a size 5 placed.

 

In the digital palpation group, the cuff was inflated as follows:

  • size 3- 20 mL
  • size 4- 30 mL
  • size 5- 40 mL

All LMAs were placed completely deflated by an experienced anesthesia provider. After placement the provider palpated the cuff and estimated intracuff pressure. Depending on the suspected cuff pressure, the provider added or removed air from the cuff. After placement a research coordinator checked the intracuff pressure with a manometer.

 

In the continuous manometry group the LMA was inflated in 10 mL increments to achieve an adequate seal and maintain positive pressure ventilation. Intracuff pressure was adjusted to < 60 cm H20 and maintained at that pressure for the duration of the anesthetic.

 

Result   There were 180 patients who completed the study. Baseline demographics and clinical characteristics were similar. Initial intracuff pressure in the digital palpation group was estimated by the anesthesia providers to be > 60 cm H20 in 92% of patients. Air was removed as needed. The median intracuff pressure in the palpation group was 130 cm H20 (range: 120-130 cm H20), compared to 10 cm H20 (range 5-37 cm H20) in the manometry group (P < 0.001). The incidence of postoperative pharyngolaryngeal complications was higher in the digital palpation group;

  • sore throat: 28% vs. 8% (P < 0.05)
  • dysphagia: 14% vs. 5% (P = NS)
  • dysphonia: 2% vs. 1% (P = NS)

No difference in severity or duration of symptoms was found.

 

Conclusion   The investigators recommend manometry be used in all patients who have an LMA placed. Digital palpation of cuff pressure was not a suitable alternative.

 

Comment

 

The evidence is pretty clear- manometry is better than digital palpation for checking and adjusting LMA intracuff pressures. At my facility one of our CRNAs who was working on his DNP implemented a manometry protocol for LMA and endotracheal tube placement. During his baseline data collection, he found the exact same thing the investigators in this study found- that LMA intracuff pressures were almost always > 60 cm H20 (usually > 120 cm H20). He briefed the department, placed manometers in all rooms, included a line to document intracuff pressure in the electronic anesthesia record, and placed a note on the anesthesia machine with recommended intracuff pressures for LMAs and ETTs. He found his manometry protocol significantly improved compliance with LMA intracuff pressures (< 60 cm H20).

 

I recommend anesthesia providers make sure they have manometers available and that they always check LMA (and ETT) intracuff pressures after placement. Or consider having your supply department order LMAs that have built-in pressure monitors (e.g., LMA® Protector™ Airway with Cuff Pilot™ Technology).

 

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.
 
This article is available free full text at the following url:


© Copyright 2018 Anesthesia Abstracts · Volume 12 Number 6, February 21, 2018




Obstetric Anesthesia
Epidemiology of cardiac arrest during hospitalization for delivery in Canada: a nationwide study

Anesth Analg 2017;124:890–7

DOI: 10.1213/ANE.0000000000001877

Balki M, Liu S, Leon JA, Baghirzada L


Abstract

 

Purpose   The purpose of this report was to describe the epidemiology of maternal cardiac arrest in Canada.

 

Background   Cardiac arrest during pregnancy can be catastrophic for mother and fetus. Therefore, it is essential that providers understand the frequency, incidence, associated conditions, potential etiologies, and survival rates of maternal cardiac arrest. One study reported maternal cardiac arrest rates of 1 in 30,000 pregnancies. In the United Kingdom the rate of maternal death between 2006 and 2008 was reported to be 1 in 50,000 births. In the United States, a review of the nationwide impaction sample of over 50 million hospitalizations for delivery found maternal cardiac arrest occurred in 1:12,000 hospitalizations for delivery, with 59% of women surviving. Because of the rarity of this event, it is essential that providers understand the epidemiology of cardiac arrest in pregnancy in Canada. This study sought to generate information on cardiac arrest in pregnancy by examining the frequency, incidence, associated conditions, and maternal and neonatal survival rates.

 

Methodology   This was a retrospective cohort study of all pregnant women with a gestational age of 20 weeks or more with cardiac arrest during hospitalization for childbirth from 2002 to 2015 in Canada. Exclusion criteria were early pregnancies with abortive outcome and ectopic and molar pregnancies. Investigators collected data on demographics, medical conditions, and maternal and neonatal outcomes. Other outcomes included rates of survival to discharge, the association between cardiac arrest and medical and obstetric conditions, and neonatal survival rates. Statistical analysis was appropriate.

 

Result   There were 286 maternal cardiac arrests out of 3,568,597 hospitalizations for childbirth between 2002 and 2015. This was a maternal cardiac arrest rate of 1 in 12,500 deliveries. Overall, 29% of parturients who experienced cardiac arrest did not survive to hospital discharge. The fatality rate of women who had cardiac arrest was 2.3 per 100,000 deliveries. Women 35 years of age or older (OR 2.3), <37 weeks gestation (OR 6.2), and pregnant ≥4 times (OR 2.0) had higher odds of cardiac arrest.

 

Obstetric conditions associated with cardiac arrest included:

  • placenta accretta (OR 3.6)
  • placental abruption (OR 3.3)
  • polyhdramnios (OR 2.5)
  • placenta previa (OR 2.3)
  • hypertension of pregnancy (OR 2.3)
  • gestational diabetes (OR 2.0)

Nonpregnancy-related medical conditions associated with cardiac arrest included:

  • malignancy (OR 8)
  • diseases of the nervous system (OR 3.6)
  • lower respiratory tract diseases (OR 2.0)

Table 1. Epidemiology of Cardiac Arrest

Condition

Cardiac Arrest N (%)*

Odds Ratio**

Survive to Discharge %

Amniotic fluid embolism

36 (12.6)

195

67%

Heart failure

90 (31.5)

29

74%

Trauma

9 (3)

21

56%

Eclampsia

20 (7)

19

85%

Complications of anesthesia

36 (13)

16.5

100%

Air / thrombo-embolism

17 (6)

12

53%

Intrapartum hemorrhage

14 (5)

5

43%

Postpartum hemorrhage

112 (39)

5

70%

Pulmonary edema

13 (4.6)

3

77%

CVA/Stroke

13 (4.6)

1.5

46%

Antepartum hemorrhage

44 (15)

0.75

73%

Notes: *Percent of all cardiac arrests attributed to this cause. **Odds of cardiac arrest occurring when this cause present vs. not present.

 

There were 28 patients (10%) who had a cardiac arrest as a result of complications of anesthesia. Three of these patients had aspiration pneumonitis, and two patients had failed/difficult intubation.

 

The overall survival rate after cardiac arrest was 71%, with the rate ranging from 25% to 100% depending upon the cause. Aortic aneurysm and dissection had the lowest survival rate at 25%, and complications of anesthesia had the highest survival, 100%. Conditions with a survival rate <50% were aortic aneurysm and dissection (25%), acute myocardial infarction (33%), intrapartum hemorrhage (43%), and cerebrovascular disorders/stroke (46%). The most common etiologies for cardiac arrest were postpartum hemorrhage (39%), heart failure (31.5%), amniotic fluid embolism (12.6%), and complications of anesthesia (12.6%).

 

Conclusion   The rate of cardiac arrest during pregnancy in Canada was 1:12,500 deliveries. This survival rate was higher than recently reported in other countries. Results should be used to develop policies and programs to reduce maternal cardiac arrest.

 

Comment

 

In this study the #1 condition associated with cardiac arrest was postpartum hemorrhage, followed by heart failure and amniotic fluid embolism. In this study approximately 6% of all deliveries experienced a postpartum hemorrhage. Postpartum hemorrhage is one of the leading causes of preventable mortality around the world. Facilities that have low rates practice good communication and teamwork. They also have protocols in place to recognize patients at risk and guide the management of a postpartum hemorrhage.

 

In contrast, amniotic fluid embolism unfortunately cannot always be detected until it is too late. In this study the rate of amniotic fluid embolism was 6 per 100,000 deliveries with almost 13% suffering a cardiac arrest, and of those, 37% did not survive to discharge from the hospital. Amniotic fluid embolism can initially present as a cardiac arrest and respiratory failure but can also have disseminated intravascular coagulopathy-like presentation, which can delay diagnosis because other more common conditions may be suspected (e.g., placental abruption). I have heard of two cases where the only initial symptoms were petechiae and signs of coagulopathy/hemorrhage and then later progressed to respiratory and cardiac arrest. Treatment unfortunately is largely supportive.1

 

I liked this study because it helps anesthesia providers anticipate what conditions might be associated with cardiac arrest. Anesthesia providers should make sure to go through their full differential diagnosis when determining the cause of cardiac arrest in a parturient.

 

Dennis Spence, PhD, CRNA


1. Kaur K, Bhardwaj M, Kumar P, Singhal S, Sing T, Hooda S. Amniotic fluid embolism. J Anaesthesiol Clin Pharmacol. 2016;32:153-159.


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.

 

This article is available free full text at the following url:

https://journals.lww.com/anesthesia-analgesia/Abstract/2017/03000/Epidemiology_of_Cardiac_Arrest_During.32.aspx


© Copyright 2018 Anesthesia Abstracts · Volume 12 Number 6, February 21, 2018




Regional Anesthesia
Anesthesia technique and mortality after total hip or knee arthroplasty: a retrospective, propensity score-matched cohort study

Anesthesiology 2016;125:724-31

DOI: 10.1097/ALN.0000000000001248

Perlas A, Chan VW, Beattie S


Abstract

 

Purpose   The purpose of this study was to evaluate the effect of anesthetic technique on 30-day mortality in patients undergoing total knee replacement or total hip replacement.

 

Background   Total joint arthroplasty is the most common surgical procedure performed in older adults. They have more comorbidities and have higher rates of morbidity and mortality after total joint arthroplasty. Neuraxial anesthesia has historically been reported to be associated with decreased blood loss, surgical site infections, and lower admission rates to intensive care units when compared to general anesthesia. However, further research is needed to determine if spinal anesthesia decreases 30-day mortality.

 

Methodology   This was a a retrospective, propensity-matched cohort study of all patients who underwent total joint arthroplasty at the Toronto Western Hospital, Ontario, Canada, over a 12-year period. Investigators compared 30-day mortality in patients who received either spinal anesthesia or general anesthesia for total knees or total hips. They also compared rates of perioperative myocardial infarction, rate of major cardiac events, pulmonary embolism, >2 units PRBC administration, hospital length of stay, and operating room time.

 

Standardized anesthetic technique and postoperative multimodal analgesic pathways were used over the years. From 2003 to 2012 total knee patients received a continuous femoral nerve block. In February 2012 this was changed to an adductor canal block with periarticular local anesthetic cocktail infiltration. Starting in 2012 topical tranexamic acid was routinely administered.

 

Result   The cohort included 5,921 total knee replacements and 4,947 total hip replacements; 79% received spinal anesthesia and 21% general anesthesia. The rate of spinal anesthesia in 2003 was 34%, and in 2014 it had increased to 91%. Spinal anesthesia was more commonly administered for total knees. Total knee patients also had fewer comorbid conditions, as evidenced by their lower ASA status. The investigators propensity matched 2,135 patients who had general anesthesia with 2,135 who had spinal anesthesia; 52% total knees and 48% total hips in both groups.

 

The 30-day mortality rate was 58% lower in those receiving spinal anesthesia; 0.19% of spinal anesthetics vs. 0.8% of general anesthetics (RR = 0.42). The rate of MI, major adverse cardiac events, pulmonary embolism, and PRBC >2 units transfused were similar in both groups (Table 1). Length of stay and operating room time was significantly lower with spinal anesthesia (P = 0.0001).

 

Table 1. Adverse Events by Anesthesia Technique

 

General Anesthesia

Spinal Anesthesia

Relative Risk

P Value

30-day mortality

0.8% (n = 17)

0.19% (n = 4)

0.42

0.0045

Myocardial infarction

1.31% (n = 28)

1.27% (n = 27)

0.97

NS

Major cardiac event

1.69% (n = 36)

1.36% (n = 29)

0.81

NS

Pulmonary embolism

1.17% (n = 25)

0.84% (n = 18)

0.67

NS

>2 u PRBCs

4.36% (n = 93)

3.28% (n = 70)

0.62

NS

Length of stay*

6.6 days

median = 5.7 days

 

0.0001

Time in OR*

84.4 min

median = 80.5 min

 

0.0001

Notes: *time reported as median values. 

 


Conclusion   Spinal anesthesia for total joint arthroplasty was associated with a 58% reduction in 30-day mortality and an approximate 1-day shorter hospital length of stay.

 

Comment

 

This was the first adequately powered study to report that neuraxial anesthesia is associated with a reduced mortality after total joint arthroplasty (0.19% vs. 0.8%). While a 0.61% lower mortality rate might not seem like much, the 30-day mortality rate is 796 per 100,000 for patients undergoing general anesthesia as compared to only 187 per 100,000 for those undergoing neuraxial anesthesia for total joint arthroplasty. This equates to a lot of lives saved (42,700 a year) when you consider over 7 million total joint arthroplasty surgeries are performed each year in the United States.

 

Unless there is a contraindication, I strongly recommend neuraxial anesthesia for these surgeries.

 

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.

 

This article is available free full text at the following url:

http://anesthesiology.pubs.asahq.org/article.aspx?articleid=2540552


© Copyright 2018 Anesthesia Abstracts · Volume 12 Number 6, February 21, 2018