ISSN NUMBER: 1938-7172
Issue 9.6 VOLUME 9 | NUMBER 6

Editor:
Michael A. Fiedler, PhD, CRNA

Contributing Editors:
Mary A Golinski, PhD, CRNA
Dennis Spence, PhD, CRNA
Steven R Wooden, DNP, CRNA, NSPM-C
Cassy Taylor, DNP, DMP, CRNA

Assistant Editor
Jessica Floyd, BS

A Publication of Lifelong Learning, LLC © Copyright 2015

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

GENERAL
Psychological sequelae of surgery in a prospective cohort of patients from three intraoperative awareness prevention trials
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Postoperative morbidity and mortality in type-2 diabetics after fast-track primary total hip and knee arthroplasty
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OBSTETRIC ANESTHESIA
Womens experiences with neuraxial labor analgesia in the Listening to Mothers II Survey: a content analysis of open-ended responses
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Effect of lateral tilt angle on the volume of the abdominal aorta and inferior vena cava in pregnant and nonpregnant women determined by magnetic resonance imaging
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PAIN
The effect of transversus abdominis plane blocks on postoperative pain in laparoscopic colorectal surgery: a prospective, randomized, double-blind trial
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REGIONAL ANESTHESIA
  A comparison of the effects of hyperbaric and isobaric bupivacaine spinal anesthesia on hemodynamics and heart rate variability
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TRAUMA
Prothrombin complex concentrate versus fresh-frozen plasma for reversal of coagulopathy of trauma: is there a difference?
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None of the editors or contributors have any real or potential conflicts of interest to disclose.


General
Psychological sequelae of surgery in a prospective cohort of patients from three intraoperative awareness prevention trials

Anesth Analg 2015;120:87-95

Whitlock EL, Rodebaugh TL, Hassett AL, Shanks AM, Kolarik E, Houghtby J, West HM, Burnside BA, Shumaker E, Villafranca A, Edwards WA, Levinson CA, Langer JK, Fernandez KC, El-Gabalawy R, Zhou EY, Sareen J, Jacobsohn E, Mashour GA, Avidan MS


Abstract

 

Purpose The purpose of this study was to identify factors, like intraoperative awareness, which may increase the risk of postoperative post-traumatic stress disorder (PTSD) symptoms.

 

Background There are over 200 million surgeries performed worldwide each year, with perhaps as many as 0.1% to 0.4% of patients undergoing general anesthesia experiencing intraoperative awareness. Patients who experience intraoperative awareness are at increased risk for developing PTSD. Other risk factors for postoperative PTSD include:

  • a history of depression
  • ICU admission
  • mechanical ventilation
  • in-hospital cardiac arrest

This study examined the psychological sequelae of surgery from a cohort of >29,000 patients from three prospective clinical trials on interventions to prevent intraoperative awareness.

 

Methodology This was a prospective cohort study of patients previously enrolled in three trials examining interventions to prevent intraoperative awareness. The three trials were:

  • B-Unaware, 9-2005 to 10-2006, N = 1,941
  • BAG-RECALL, 5-2008 to 5-2010, N = 5,713
  • MACS, 5-2008 to 5-2010, N = 18,836.

In those studies, 68 patients experienced definite or possible intraoperative awareness (0.26%). These patients were matched on age, surgery, gender, awareness risk, and institution with 418 patients who did not experience intraoperative awareness. Inclusion criteria from these trials were:

  • B-Unaware & BAG-RECALL: patients at high risk for intraoperative awareness undergoing general anesthesia. High-risk patients had at least one of the following:
    • preoperative long-term use of anticonvulsants, opiates, benzodiazepines, cocaine, or daily alcohol consumption
    • history of cardiac ejection fraction <40%, aortic stenosis, end-stage lung disease, marginal exercise tolerance, pulmonary hypertension, intraoperative awareness, difficult intubation or anticipated difficult intubation, ASA physical status IV or V, or planned open-heart surgery
  • MACS: included patients at all risk levels receiving general anesthesia with inhalation and/or intravenous anesthetics

 

The investigators contacted patients between August 2010 and December 2011. Each patient was asked to complete the PTSD Checklist-Specific (PCL-S) and a telephone interview using a modified version of the Mini-International Neuropsychiatric Interview (mMINI). A cut-score of 30 on the PCL-S was selected to discriminate between patients with clinically significant PTSD symptoms and those without. A psychologist administered the mMINI. Questions elicited information about the symptoms and severity of PTSD, degree of social support, PTSD symptoms from the index surgery which had resolved before the interview, and past PTSD from other events. The interview also included two questions to examine perioperative experiences of dissociation (feeling that one is numbed, dazed, or dreaming during real events).

 

Statistical analysis was appropriate. Structural equation modeling and confirmatory factor analysis were used to produce a composite PTSD score and to identify potential risk factors.

 

Result In the original three trials there were 68 cases of definite or possible intraoperative awareness. They were matched with 418 controls patients with no intraoperative awareness. Only 49 awareness patients agreed to participate in the study. In the no intraoperative awareness control group 254 patients agreed to participate. In the intraoperative awareness group 31 patients completed both the PCL-S and mMINI, and 165 did so in the no intraoperative awareness control group. Patients who participated in the study were significantly more likely to have reported distress during the intraoperative awareness event, had a shorter time since their index surgery, were more likely to have had an ICU stay, and were at lower risk for intraoperative awareness (P < 0.05). Of those patients who participated, 12% were from the B-UNAWARE trial, 35% from the BAG-RECALL trial, and 52.5% from the MACS trial (P < .001).

 

Demographics and clinical characteristics based on PCL-S scores are presented in Table 1. PCL-S scores ≥30 indicated patients experienced PTSD symptoms after surgery. PCL-S scores were ≥30 in 43% of patients in the intraoperative awareness group (15 of 35) and 16% of patients in the no intraoperative awareness group (29 of 186). Experiencing intraoperative awareness was associated with an absolute 27% increase in the occurance of PTSD symptoms . Of these patients, 14% in the intraoperative awareness group and 7.6% in the no intraoperative awareness group reported symptoms during both the PCL-S and mMINI interview. This finding was consistent with a presumptive diagnosis of PTSD related to their surgery (overall prevalence rate = 8.7%).

 

Table 1. Comparison of PCL-S Score ≥30 or <30

 

PCL-S <30

N = 44

PCL-S ≥30

N = 175

P-Value

Age

57 (46-67)

53 (47-61)

NS

Female Gender

46%

43%

NS

Cardiac Surgery

27%

14%

NS

ICU stay

36%

25%

NS

Definite or possible awareness

11%

34%

<0.001

 

Six significant predictors of PTSD complex symptoms were identified (Table 2). PTSD symptoms were worse if patients had:

 

1. a prior history of PTSD

2. low social support

3. a history of mental health treatment

4. experienced possible or definite intraoperative awareness

5. a perceived threat to life at the time of surgery

6. dissociation at time of surgery (feeling numbed, dazed, or dreaming during real events)

 

Age, gender, ICU stay, and cardiac surgery were not significant predictors of severity of PTSD symptoms.

 

Structural equation modeling indicated that dissociation experiences during surgery mediated the effect of intraoperative awareness on PTSD symptom development. Mediating variables are seen as intervening factors that can change the impact of a predictor (i.e., intraoperative awareness) on an outcome (i.e., PTSD).

 

Table 2. Predictors of PTSD Symptoms*

 

Standardized Estimate

P-Value

Past PTSD symptoms

0.55 if yes

0.003

Perceived social support

-0.20 per SD

0.006

Previous mental health treatment

0.19 if yes

0.017

Intraoperative awareness

0.47 if yes

0.014

Dissociation at time of surgery

0.39 per SD

<0.001

Perceived degree of threat to life during surgery

0.21 per SD

0.002

Note: Standardized Estimate is the number of standard deviations (SD) by which the value of the predictor is expected to change the severity of PTSD symptoms. Example: if a patient has no history of PTSD (+ 0), a low level of social support (2 SD below mean: -2 x -0.20 = +0.40), no previous mental health treatment (+ 0), experienced intraoperative awareness (+0.47), a high degree of dissociation at time of surgery (3 SDs above mean: 3 x 0.39 = +1.17), and had a moderate degree of perceived threat to life during surgery (2 SDs above mean: 2 x 0.21 = +0.42), their PTSD complex symptom severity is estimated to be 0 + 0.40 + 0 + 0.47 + 1.17 + 0.42 = 2.46, or approximately 2.5 SDs above the mean severity for all people who underwent surgery.

* Based on Confirmatory Factor Analysis

 

Conclusion The investigators confirmed intraoperative awareness was a risk factor for PTSD symptom development, but also found 16% of patients who did not report intraoperative awareness reported PTSD symptoms secondary to their surgery, and that 7.6% of these patients possibly met diagnostic criteria for PTSD. Screening patients with risk factors, such as intraoperative awareness or perioperative dissociation, for postoperative PTSD symptoms with the PCL-S could help promote early mental health referral.

 

Comment

I was surprised to find that close to 16% of patients who did not experience possible or definite intraoperative awareness reported PTSD symptoms after their surgery. When the investigators combined the results from the PCL-S and mMINI they found 7.6% of these patients met diagnostic criteria for PTSD. For those experiencing intraoperative awareness, 14% met the diagnostic criteria for PTSD.

 

These results indicate it is not uncommon for patients to develop negative psychological sequalae, such as PTSD, after surgery. The investigators suggested anesthesia providers and surgeons might want to screen patients who present with an elevated risk for PTSD secondary to their surgery with the PCL-S. While the PCL-S is fairly simple to administer, I do not know if I would feel comfortable administering the PCL-S to a patient. Although, if I felt the patient was at risk for developing PTSD (i.e., reported intraoperative awareness) I would certainly recommend a mental health referral, especially if I knew the patient had a history of mental health treatment or prior PTSD. I might also ask the patient if they experienced any dissociation during the surgery or reported feeling scared or threatened at the time the awareness occurred.

 

There are some limitations to this study. Close to 50% of the patients in this study were considered high risk for intraoperative awareness. Also those who participated were more likely to have experienced possible or definite intraoperative awareness. Therefore, there is the potential for selection bias. Recall bias may be an issue, given the median time to completion of this study was 2 years (range 2-6 years) from the patient’s index surgery. To me it is scary that some patients who experienced intraoperative awareness could still be having PTSD symptoms up to six years after their 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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015





Postoperative morbidity and mortality in type-2 diabetics after fast-track primary total hip and knee arthroplasty

Anesth Analg 2015;120:230–8

Jørgensen CC, Madsbad S, Kehlet H, Lundbeck Foundation Centre for Fast-track Hip and Knee Replacement Collaborative Group


Abstract

 

Purpose The purpose of this study was to determine if diabetes was associated with a length of stay >4 days, higher 30-day and 90-day readmission rates, or greater postoperative morbidity and mortality in patients undergoing total joint replacement under a fast-track protocol.

 

Background Many patients undergoing total knee and hip replacement present with diabetes. Diabetes is associated with postoperative morbidity and mortality. A fast-track approach to recovery has been shown to decrease insulin resistance postoperatively. However, it is not known if diabetes is an independent risk factor for postoperative morbidity and mortality, increased length of stay, and readmission rates in patients undergoing a fast-track recovery protocol which includes optimized perioperative care with spinal anesthesia, multimodal opioid-sparing analgesia, early mobilization, and faster discharge to home (<4 days).

 

Methodology This was a retrospective, observational cohort study of all patients undergoing total knee or hip arthroplasty included in a Danish Fast-track Hip and Knee Replacement Collaborative Group Registry. In the registry, 7,165 non-diabetic patients were matched with 890 patients with type-2 diabetes. Multiple logistic regression was used to examine differences in:

  • length of hospital stay >4 days
  • 30-day and 90-day readmission rates
  • a composite of diabetes-related morbidity

Patients with type-2 diabetes were compared to those without diabetes. Investigators also conducted subanalyses according to antihyperglycemic treatment. Diabetes-related morbidity included:

  • all wound infections
  • arrhythmias or cardiac events
  • strokes or transient ischemic attacks
  • postoperative renal insufficiency
  • postoperative dysregulated blood glucose
  • urinary tract infections.

 

Result Patients with type-2 diabetes had higher rates of hypertension (81% vs. 51%), hypercholesterolemia (70% vs. 25%), and cardiac disease (21% vs. 12%) than those without diabetes (P < 0.05). A majority of the type-2 diabetic patients were on oral antihyperglycemic agents (67%) but 20% were treated with insulin.

 

Length of stay >4 days, 30-day and 90-day readmission rates, and diabetes-related morbidity were all higher in patients with type-2 diabetes (Figure 1). However, after adjustment for covariates, no significant difference was found. Comparisons of causes of a length of stay >4 days found type-2 diabetics had significantly higher rates of renal insufficiency (0.9% vs. 0.3%, P = 0.012), urinary tract infections (0.6% vs. 0.2%, P = 0.01), and cerebral complications (transient ischemic attacks, stroke, or cerebral bleeds; 0.6% vs. 0.2%, P = 0.016) compared to nondiabetics. Mortality was similar in both diabetics and nondiabetics (0.3%, Figure 1). After adjusting for covariates, patients with insulin-treated type-2 diabetes were found to have higher rates of diabetes-related morbidity when compared to nondiabetics (P = 0.016).

 

Figure 1. Comparison of Outcomes

Figure 1

Notes: P-value adjusted for age, body mass index (BMI), sex, operated joint, living alone/institution, use of walking aids, cardiac disease, hypertension, hypercholesterolemia, hospital, and propensity score. No interactions were found with regard to presence of type 2 diabetes and BMI, hypertension, hypercholesterolemia, or cardiac disease.

 

Conclusion Type 2 diabetes had limited influence on perioperative morbidity and mortality in fast-track total joint arthroplasty patients. However, patients with insulin-dependent type-2 diabetes did have higher rates of renal, urologic, and cerebral complications compared to nondiabetics.

 

Comment

It is important that anesthesia providers understand the comorbidities diabetics may present with and the postoperative complications they may experience. In this study, type-2 diabetics had higher rates of cardiac disease, hypertension, and hypercholesterolemia. The investigators found longer lengths of stay >4 days, higher 30-day and 90-day readmission rates, and more diabetes-related morbidity in patients with type-2 diabetes. But when they controlled for other comorbidities, diabetes alone was not associated with these outcomes. This does not mean we should ignore the effect diabetes has on perioperative morbidity and mortality but that we should be aware that diabetics present with other comorbidities which probably have a greater impact on negative postoperative outcomes than the type-2 diabetes itself.

 

In fact, type-2 diabetics on insulin, did have higher rates of diabetes-related morbidity. This morbidity included wound infections, arrhythmias or cardiac events, strokes or transient ischemic attacks, postoperative renal insufficiency, postoperative dysregulated blood glucose, and urinary tract infections. While the investigators didn’t specify, I suspect type-2 diabetics on insulin had higher rates of renal insufficiency, urinary tract infections, and cerebral complications such as transient ischemic attacks or strokes, given these rates were found to be higher in diabetics who had a >4 day length of stay.

 

There are limitations to this study. We do not know the severity of the patients’ diabetes or how well it was controlled. No HbA1C data were presented. Because this was a retrospective study, there is the possibility of coding errors and unmeasured covariates that may have influenced the outcomes. Nonetheless, I feel this was a good study that can help anesthesia providers anticipate what potential complications may occur in type-2 diabetics undergoing total joint arthroplasty under a fast-track protocol.

 

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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015




Obstetric Anesthesia
Womens experiences with neuraxial labor analgesia in the Listening to Mothers II Survey: a content analysis of open-ended responses

Anesth Analg 2014; published ahead of print

Attanasio L, Kozhimannil KB, Jou J, McPherson ME, Camann W


Abstract

 

Purpose The purpose of this study was to conduct a qualitative analysis of women’s open-ended responses about the best and worst parts of their birth experiences related to neuraxial analgesia.

 

Background Over 61% of parturients in 2008 received neuraxial analgesia for pain relief during labor. Hundreds of studies have been conducted which have examined outcomes from various neuraxial analgesic techniques. However, few studies have examined how neuraxial analgesia affected women’s birth experiences. In 2005 the Listening to Mothers II Survey was conducted, which surveyed a nationally representative sample of women who delivered in the United States. The purpose of this study was to conduct a secondary analysis to identify positive and negative themes related to neuraxial analgesia from women’s open-ended responses from the survey.

 

Methodology The Listening to Mothers II survey was conducted in 2005 and included a nationally representative sample of 1,573 women who delivered in the United States. Three of the questions on the survey elicited open-ended responses to the following:

 

1. Apart from meeting your new baby, and knowing that your baby had no serious health concerns, what was the best part about    

    your experience of giving birth?

2. What is the worst thing that happened to you during your labor and birth?

3. Is there anything else you would like to tell us about any aspect of your maternity experience?

 

There were no specific open-ended questions about neuraxial analgesia on the survey. Women were excluded if they reported undergoing an elective cesarean delivery or did not receive neuraxial analgesia for labor pain relief. Qualitative content analysis was used to identify themes related to neuraxial analgesia from women’s open-ended responses to the three questions.

 

Result On the survey, 914 women reported receiving neuraxial analgesia for labor (58% of survey respondents). Eighty percent of respondents reported some college education, 69% were Caucasian (non-Hispanic), 87% were between the ages of 18 and 34 years old, 73% were married, and 61% had private insurance. Labor induction occurred in 57% of respondents, 67% received oxytocin, and 7.3% reported feeling pressured to have an epidural.

 

Of the 914 respondents who reported receiving neuraxial analgesia, 300 spontaneously described experiences with neuraxial analgesia in one or more of the three questions (33%). Some women’s responses were coded more than once. Four major themes emerged from the analysis (Table 1). Positive themes were quite common, and responses were rather homogeneous. Many commented that the epidural was the “best part” of the labor process and that the epidural provided effective pain relief. Many commented on the good bedside manner of the anesthesia provider. For example, one woman commented on how the anesthesia provider was kind and talked her through the whole epidural placement. A few women commented that they decided on their own, without pressure from staff, to get an epidural.

 

Negative responses were reported by 5% of the 914 women in the sample. Forty-eight (16%) of the 300 women who commented on neuraxial analgesia had negative comments. Some of the negative comments were related to having to wait to get their epidural or the epidural not being as effective as they had expected. Many of the negative comments were related to lack of communication between nurses and/or anesthesia providers and the women about what to expect. For example, the anesthesia provider did not inform the patient during the consent process that they may experience motor block or a unilateral block. A few of the women’s comments suggested staff were less than empathetic. Some women reported feeling guilty or that they had failed because they had received an epidural.

 

Table 1. Themes Related to Neuraxial Analgesia

Theme

N

Exemplar Quote

1. Neuraxial analgesia as “best part” of birth experience

52

The epidural was excellent since it took away the pain and allowed me to enjoy the process of giving birth.

2. Effective pain relief

47

3. Challenges related to timing of neuraxial analgesia

 

 

-Waiting in pain

31

They didn’t give me the epidural early enough. The [anesthesia provider] was in surgery and so I was in a lot of pain until he could get there.

-Wore off too soon

23

[The epidural] only helped for a brief period of time... and by the time I was ready to deliver it had worn off completely.

-Administered late in labor

15

I requested [the] epidural when I was 5–6 centimeters dilated. It took a long time to arrive, over an hour… Had epidural too late and would have liked to been advised not to take epidural because I was in transition.

-Information and consent

21

The nurse assigned to me was not helpful in pain management suggestions…and only turned up to say “The [anesthesia provider] is here giving someone else an epidural, do you want one?”

4. Adverse experiences

 

 

-Less effective than expected

58

(Authors reported several women commented they experienced patchy or unilateral blocks.)

-Negative physical effects

50

After receiving the epidural, my left leg went completely numb during labor, making it difficult to push.

-Problems with placement

34

(Authors reported several women commented they experienced pain during placement, that it took multiple needle punctures, and that they had difficulty sitting still.)

-Plans and expectations for neuraxial analgesia

20

I originally wanted to give birth without an epidural, but changed my mind about 14 hours after labor began. For a while I felt a little guilty about “giving in,” but came to realize that each labor is different and a “woman’s got to do what a woman’s got to do.”

Note: Some quotes fit more than one theme. There were N = 300 of 914 women who commented in open-ended responses on neuraxial analgesia.

 

Conclusion Overall, women very much appreciate the pain relief and positive effects neuraxial analgesia had on their birthing process. Greater communication between anesthesia providers, nurses, and patients about expectations and analgesic alternatives may help minimize negative experiences attributed to neuraxial analgesia.

 

Comment

In this era of the “patient experience” it is critical that obstetric anesthesia providers do everything they can to improve the birth experience. A big marketing tactic for hospitals is the availability of a 24-hour labor anesthesia service. Being empathetic to the patient, and really trying to do whatever you can, within reason, to get their pain level to where they can safely enjoy the birthing process is important; although, sometimes that might mean they need a denser block. However, we need to do a good job of informing patients about the labor process and making sure they have realistic expectations and understand that sometimes epidurals do not work 100%, that sometimes they may experience significant motor or unilateral block, and that occasionally we have to replace the epidurals. It is also important that nursing staff communicate closely with the anesthesia provider on duty and consider other analgesic options if the anesthesia provider is unavailable to place their epidural “on-demand.” Finally, maintaining good relations with nursing staff is also key. They can be our best (or worst) advocates!

 

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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015





Effect of lateral tilt angle on the volume of the abdominal aorta and inferior vena cava in pregnant and nonpregnant women determined by magnetic resonance imaging

Anesthesiology 2015;122:286-93

Higuchi H, Takagi S, Zhang K, Furui I, Ozaki M


Abstract

 

Purpose The purpose of this study was to compare differences in aorta and inferior vena cava (IVC) volume between 10 healthy term parturients and 10 healthy nonpregnant female volunteers while supine or tilted laterally 15º, 30º, or 45º.

 

Background Obstetricians and anesthesia providers have been taught to avoid compression of the aorta and vena cava (aortocaval compression) in the term parturient by using a 15º tilt. This is thought to improve uterine blood flow and uteroplacental perfusion. However, the American Heart Association recommends a 30º tilt during resuscitation in pregnant women. Therefore, the authors of this study sought to compare differences in aorta and IVC volume using MRI in term parturients and healthy volunteers in the supine, 15º, 30º, and 45º tilt positions.

 

Methodology Ten healthy term Japanese parturients between 37 and 39 weeks gestation and ten healthy nonpregnant females were recruited to undergo an MRI study comparing aorta and IVC volume in the supine, 15º, 30º, and 45º tilt positions. Measurement of the aorta and IVC volume between the L1–L2 disk and L3–L4 disk levels was conducted in both the supine and left-lateral tilt positions. The tilt was maintained by insertion of a 1.5-meter-long piece of polyethylene foam placed under the right side of the patient’s body. Cardiac output (CO), mean arterial pressure (MAP), and heart rate (HR) were measured in each position using thoracic bioimpedance. Thoracic bioimpedance cardiography was measured with the BioZ instrument (Cardio Dynamics International, San Diego, CA). An automated noninvasive blood pressure device attached to the right arm was used to measure blood pressure.

 

Result The mean age of both groups was 34 years. Mean weight was 57 kg in the parturients and 49 kg in the control group (P < 0.05). No significant differences were found in aortic volume between or within the groups in any of the tilt positions (Figure 1). However, parturients in the supine, 15º, 30º, and 45º tilt positions had significantly lower IVC volumes compared to the control group (P < 0.01; Figure 2). Within the parturient group, the 30º and 45º tilt positions resulted in a significant increase in IVC volume compared to the supine position (P < 0.005). The 15º tilt was no better than the supine position. No differences in CO, MAP, or heart rate were found between or within the groups in the various tilt positions.

 

Figure 1. Differences in Aorta Volume

Figure 1

 

Figure 2. Differences in IVC Volume

Figure 2

 

Conclusion In term, non-obese, non-laboring parturients the aorta was not compressed in the supine or 15º, 30º, and 45º tilt positions. However, the IVC was significantly compressed in the supine and 15º tilt positions. The 15º tilt position may not effectively reduce IVC compression during pregnancy. Use of the 30º and 45º tilt positions significantly improved IVC volume, although CO, MAP, and heart rate were unaffected by changes in tilt position.

 

Comment

I like reading studies that question traditional practices to see if the evidence holds up. What this study suggests is that the aorta is not significantly compressed at term in various tilts and that ≥30º tilt may be needed to relieve IVC compression in term parturients. There are a few caveats to these findings. First, these parturients were not in labor. Additionally, the average weight in this study (57 kg) was probably much lower than what we see in term parturients in the United States (i.e., >70 kg). I suspect there may have been a more dramatic effect on IVC compression and possibly compression on the aorta in laboring parturients from the United States.

 

I would have liked to have seen fetal heart rates reported for the different tilt positions, as this would have given us more information on the clinical implications of these various tilt positions. I suspect in the supine position at term that in addition to aortocaval compression, that sometimes the nuchal cord might get compressed in the supine position. This compression combined with compression of the IVC and aorta, especially in the presence of a sympathectomy secondary to neuraxial anesthesia, might combine to decrease perfusion to the fetus.

 

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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015




Pain
The effect of transversus abdominis plane blocks on postoperative pain in laparoscopic colorectal surgery: a prospective, randomized, double-blind trial

Dis Colon Rectum 2014;57:1290–1297

Keller DS, Ermlich BO, Schiltz N, Champagne BJ, Reynolds HL Jr, Stein SL, Delaney CP


Abstract

 

Purpose The purpose of this study was to determine if the addition of a surgeon-administered transverse abdominus plane (TAP) block decreased pain scores, opioid consumption, length of stay, and 30-day readmission rates in colorectal surgery patients.

 

Background TAP blocks decrease pain and opioid consumption after a variety of surgical procedures. TAP blocks can be administered blindly, laparoscopically under direct vision by the surgeon, or by an anesthesia provider using ultrasonography. TAP blocks are field blocks that can block the T-9 to L-1 sensory nerves that innervate the abdomen. A previous retrospective study by these investigators found the addition of a TAP block after laparoscopic-assisted colorectal surgery decreased hospital length of stay from 3.2 to 2.1 days. The authors hypothesized those patients who received a TAP block would have significantly less postoperative pain, lower rates of postoperative opioid use, and shorter hospital length of stay compared with a control group that did not receive a TAP block.

 

Methodology Patients undergoing laparoscopic or hand-assisted colorectal surgery were enrolled in this prospective, double-blind, placebo-controlled study. All patients received the following as part of the enhanced recovery pathway:

  • Preoperatively
    • Diclofenac sodium 100 mg evening before surgery
    • Gabapentin 300 mg 1 - 2 hours before surgery
  • Postoperatively
    • Gabapentin 300 mg orally twice a day for 72 hours (or while in the hospital)
    • Toradol 15 mg intravenously every 6 hours for 48 hours
    • Tylenol 1 g IV every 6 hours
    • Postoperative day 1 - morphine PCA discontinued
    • Tylenol transitioned from IV to oral
    • Oxycodone 10 mg orally every 6 hours as needed

At the completion of the surgery, one of four surgeons blinded to group assignment performed a bilateral TAP block procedure under laparoscopic visualization between the costal margin and iliac crest in the anterior axillary line using one of the two following solutions:

  • Control: 0.5 mL/kg of 0.9% normal saline - maximum 30 mL
  • Experimental: 0.5 mL/kg of 0.5% bupivacaine - maximum 30 mL

Total block cost was $14.17. Data collected included pain scores, opioid consumption, length of stay, 30-day readmission rates, and complications.

 

Result No significant differences were noted in demographics, type of surgical procedure, or intraoperative opioid requirements between the two groups. Seventy-nine subjects were enrolled (TAP block group n = 41 vs control group n = 38). The TAP block group had significantly lower pain scores in the recovery room (2.1 vs. 3.8, P < 0.0001) and on postoperative day 1 (2.5 vs 3.6, P = 0.04). Pain scores declined and continued to be lower in the TAP block group over the next four days. Mean pain scores on postoperative days 1-5 were 2.6 (TAP block) vs. 3.5 (control group), (P = 0.04). Opioid consumption was significantly lower in the TAP block group in the recovery room (mean Dilaudid, 0.80 mg vs 1.79 mg, P < 0.001). No significant differences in postoperative nausea and vomiting were found between the groups. However, opioid consumption was similar between the two groups during postoperative days 1-5. No statistically significant differences were found in the median length of stay between the TAP block and control group (2 days [1-13] vs 3 days [1-8]) or in readmission rates (7.3% vs 5.3%). Patients in the TAP block group were able to return to normal activities of daily living earlier; however, these differences were also not statistically significant (7.8 ± 4.4 vs 10.8 ± 9.7).

 

Conclusion Surgeon-administered TAP blocks with 0.5% bupivacaine 30 mL reduced early pain and opioid consumption. However, no differences were found in postoperative days 1-5 opioid consumption, hospital length of stay, or 30-day readmission rates. Future studies should examine if longer-acting local anesthetics improve long-term outcomes and decrease health care costs after laparoscopic colorectal surgery.

 

Comment

Over the last several years there has been an increasing interest in use of TAP blocks for postoperative pain relief. At my institution we routinely perform this field block under ultrasound guidance at the end of exploratory laparotomy and total abdominal hysterectomy procedures. We have been finding good results, especially when we use long-acting local anesthetics such as liposomal bupivacaine.

 

I must admit this was the first study I have read that described outcomes of surgeon-administered TAP blocks at the end of laparoscopic surgery. I found one other study1 which described a similar technique after laparoscopic hysterectomy. This technique is especially appealing because the surgeon can directly visualize the spread of the local anesthetic in the correct fascial plane with the laparoscope. Also this technique does not significantly increase operative time and does not require an ultrasound machine or anesthesia provider proficient in performing a TAP block. I would encourage readers to talk with your surgeons about the technique and consider incorporating it into your multimodal analgesic plans.

 

Dennis Spence, PhD, CRNA


1. Calle GA. Transversus abdominis plane block after ambulatory total laparoscopic hysterectomy: randomized controlled trial. Acta Obstet Gynecol Scand. 2014;93:345-50.

 


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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015




Regional Anesthesia
A comparison of the effects of hyperbaric and isobaric bupivacaine spinal anesthesia on hemodynamics and heart rate variability

Turk J Med Sci 2014;44:224-231

Toptaş M, Uzman S, İşitemiz İ, Uludağ Yanaral T, Akkoç İ, Bican G


Abstract

 

Purpose The purpose of this study was to examine the effects of isobaric and hyperbaric bupivacaine spinal anesthesia on hemodynamics and heart rate variability.

 

Background Spinal anesthesia offers the advantage of rapid and reliable anesthesia; however, hypotension is common, with a frequency ranging from 5% to 56%. Heart rate variability is a noninvasive measurement of the beat-to-beat variability in heart rate and reflects a balance between the sympathetic and parasympathetic nervous systems. Higher Heart Rate Variability reflects increased vagal tone and parasympathetic nervous system activity, whereas lower Heart Rate Variability reflects higher sympathetic system activity. The high frequency (HF) component of Heart Rate Variability derived from spectral analysis reflects increased cardiovagal activity. The low frequency (LF) component is affected by sympathetic activity, and the ratio between the LF/HF represents the sympathovagal balance, with higher basal levels being associated with hypotension after spinal anesthesia. Low heart rate variability and higher basal low frequency/high frequency ratios (LF/HF) >2.5 have been purported to be predictive of hypotension after spinal anesthesia. This study sought to examine changes in Heart Rate Variability and its components during spinal anesthesia with either isobaric or hyperbaric 0.5% bupivacaine.

 

Methodology This was a prospective randomized controlled study of sixty patients undergoing ambulatory surgery that could be done under spinal anesthesia. Patients aged 18 years to 65 years were randomized to receive either 3 mL of isobaric or hyperbaric 0.5% bupivacaine (15 mg). Patients were excluded if they had a history of hypertension, diabetes, cardiovascular disease, potential need for a blood transfusion, were on beta blockers, planned surgeries longer than 2 hours, and body mass indexes of under 18 or over 25.

 

All patients received a 500 mL bolus of 6% hetastarch over 15 minutes. Spinal anesthesia was administered with the patients in the sitting position. No premedication was given. Immediately after injection of the spinal anesthetic, patients were positioned supine with a 30 degree upward position. Sensory block was evaluated according to dermatomal spread using a pinprick test. Vital signs and sensory block levels were measured prior to the fluid bolus (baseline), after the fluid bolus, and then at 1, 3, 5, 10, 15, 20, 25, and 30 minutes. Heart Rate Variability was measured on the morning of the operation, after the fluid bolus, and at 20 minutes after spinal injection. Heart Rate Variability parameters measured included the High Frequency (HF), Low Frequency (LF), and LF/HF ratio. Hypotension was defined as a systolic blood pressure decrease of 20% from baseline. Patients with a 20% to 30% drop in systolic blood pressure received a rapid infusion of 500 mL 6% hetastarch. If there was no response or if the blood pressure decreased >30% then 5 mg ephedrine was administered. If the heart rate dropped below 50, atropine 0.5 mg was administered. Statistical analysis was appropriate. No other sedatives or opioids were administered.

 

Result No significant differences were found in baseline demographics. There were 53 males and 7 females (4 in isobaric group and 3 in hyperbaric group). The mean age was 37 ± 13 years. In the isobaric group 23% experienced hypotension compared to 27% in the hyperbaric group (P = NS). Only one patient in the hyperbaric group required ephedrine. Bradycardia (heart rate < 50) occurred in 10% of patients in the isobaric group and in 6% in the hyperbaric group (P = NS). Maximal sensory block levels were similar for the isobaric vs. hyperbaric group; median T-7 [T4-T11] vs. T-8 [T4-T12], (P = NS).

 

There were no significant differences in Heart Rate Variability components between the groups. In the hyperbaric bupivacaine group the LF/HF ratio was significantly lower and the HF values were significantly higher 20 minutes after the spinal injection (P < 0.05). Five minutes after the spinal injection, patients in the hyperbaric bupivacaine group had significantly higher systolic blood pressure compared to the isobaric bupivacaine group (P < 0.05). No differences were found at any other time points (Figure 1). Heart rate values were similar between the groups. However, both groups had a significant increase in their heart rates at 1, 3, and 5 minutes compared to baseline. Heart rates increased from approximately 70 at baseline to 78-80 (P < 0.05). Heart rates in both groups then declined over the next 25 minutes towards baseline values.

 

Figure 1. Differences in Systolic Blood Pressure

Figure 1

 

Conclusion While sensory dermatome block heights were similar, hyperbaric bupivacaine did have a significantly increased Heart Rate Variability. This was reflected in an increased HF frequency and a decreased LF/HF ratio.

 

Comment

I thought this was an interesting study because it really helps us to understand how differences in baricity of local anesthetics affect segmental block height. With hyperbaric spinal anesthetics there is a zone of differential blockade, with motor block being 1-2 dermatomes below the sensory level (as measured by pinprick), and sensory block being 1-2 dermatomes below the sympathetic (as measured by temperature discrimination) dermatome level. As the sympathetic level rises above T4, so does the likelihood that cardio-accelerator fibers will be blocked.

 

What this study shows is that 15 mg of hyperbaric bupivacaine in average height patients with a 30 degree head-up position will have some degree of blockade of cardio-accelerator fibers and increased vagal tone as reflected by the Heart Rate Variability changes at 20 minutes. The isobaric group also had Heart Rate Variability changes, but they were not significantly different compared to baseline. The aggressive treatment of hypotension and bradycardia limits the interpretation of differences in Heart Rate Variability between and within the groups. Although what we do see is that heart rate and blood pressure started to stabilize around 15 minutes, which is clinically what we tend to see.

 

Hyperbaric spinal anesthetics tend to be gravity dependent, whereas gravity has minimal effect on isobaric spinal anesthetic block height. The lack of differences in sensory dermatome levels was probably related to the 30 degree head-up position used in the hyperbaric group.

 

Overall, I felt this was a good study of the physiological effects of local anesthetics on Heart Rate Variability.

 

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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015




Trauma
Prothrombin complex concentrate versus fresh-frozen plasma for reversal of coagulopathy of trauma: is there a difference?

World J Surg 2014;38:1875-1881

Bellal J, Hassa A, Pandit V, Hays D, Kulvatunyou N, Zeeshan Y, Tang A, O’Keefe T, Green D, Friese R, Rhee P


Abstract

 

Purpose The purpose of this study was to compare the time needed to correct trauma-related coagulopathy in patients who received prothrombin complex concentrate (PCC) + fresh-frozen plasma (FFP) versus those who received FFP only during resuscitation.

 

Background Many trauma patients develop coagulopathy. The cause is multifactorial and is caused by hypoperfusion, hypothermia, acidosis, consumption of clotting factors, and dilution due to administration of crystalloids. Coagulopathy is often corrected in trauma patients by the administration of Fresh Frozen Plasma. However, delays in, or limited availability of, FFP may delay reversal of coagulopathy.

 

Numerous studies have demonstrated the efficacy of recombinant factor VIIa (rVIIa) in correcting coagulopathy; however, the high costs and limited availability of rVIIa has limited its widespread use. Recent studies suggest Prothrombin Complex Concentrate (PCC) can help rapidly correct coagulopathy in trauma patients. Profilnine SD is a Prothrombin Complex Concentrate mixture of vitamin K-dependent clotting factors: Factor IX (antihemophilic factor B), Factor II (prothrombin), Factor X (Stuart-Prower Factor), and low levels of Factor VII (proconvertin) derived from human plasma (dose 25 mg/kg). It is FDA-approved for the prevention and control of bleeding in patients with Factor IX deficiency due to hemophilia B. However, it is emerging as an off-label replacement for rVIIa in the treatment of trauma-related coagulopathy. The advantage of PCC is that it contains additional clotting factors, whereas rVIIa is only factor VII, and thus may be advantageous when administered with FFP for correction of trauma-related coagulopathy.

 

Methodology This was a retrospective case-control study using prospectively collected data from a single Level I trauma Center. All trauma patients in the study were coagulopathic on admission with an INR ≥ 1.5. Patients in the study received PCC+FFP during 2011 and 2012 and were propensity-matched to a control group who received FFP only during the years 2006 to 2010. The investigators compared the following parameters:

  • time to correction of coagulopathy
  • blood product requirements
  • thromboembolism events
  • complications
  • mortality
  • costs

Patients on warfarin were excluded. Patients were matched for demographics, injury severity, and initial INR. In 2008 investigators implemented damage control resuscitation principles, which included minimization of crystalloids, ratio-based blood product administration (1:1), and early factor replacement.

 

Result A total of 5,420 trauma patients were included in the trauma registry. Of these, 22.5% (1,220) were coagulopathic on admission. There were 318 patients who received PCC+FFP. Of these, 63 patients who received PCC+FFP were propensity score matched to 189 patients who received only FFP during their resuscitation. The average age of participants was 44 ± 20 years. Seventy percent were male, and blunt injury was the most common injury type. No significant differences were found in demographics, initial INR (2.2 vs. 2.1), or admission characteristics. The time to initiation of therapy was 68 min in the PCC+FFP group and 74 min in the FFP group (P = NS).

 

Correction of the coagulopathy was significantly faster in the PCC+ FFP group (P < 0.001; Figure 1). The proportion of patients who received a 1:1 PRBC to FFP ratio was greater in the PCC+FFP group compared to the FFP group (60% vs. 48%); however, this difference was not significant (Table 1). No differences were found in thromboembolic complications. Mortality was significantly lower in the PCC+ FFP group (23% vs. 28%, P = 0.04). Cost of therapy was higher in the PCC + FFP group (P = 0.02); however, the cost of transfusion was higher in the FFP only group (P = 0.01; Table 1).

 

Figure 1. Time to correction of INR

Figure 1

 

Table 1. Outcomes

 

PCC+FFP

(n = 63)

FFP

(N = 189)

P value

PRBC (units)

6.6 ± 4.1

10 ± 8.3

0.001

FFP (units)

2.8 ± 1.8

3.9 ± 1.3

0.01

Platelets (units)

1.2 ± 2.1

1.5 ± 2.7

NS

PRBC:FFP (1:1)

60.3%

48.1%

NS

Mortality, n (%)

15 (23%)

53 (28%)

0.04

Cost of therapy

$1,470 ± 845

$1,171 ± 949

0.02

Cost of transfusion

$7,110 ± 1,068

$9,571 ± 1,524

0.01

Hospital cost

$50,910 ± 47,773

$50,080 ± 40,832

NS

Note: NS = not significant

 

Conclusion The addition of PCC to FFP rapidly corrected trauma-related coagulopathy compared to FFP alone. The administration of PCC + FFP was also associated with decreased mortality, reduced blood product administration, and therapy costs. The overall cost of care was not significantly different despite the improved outcomes and additional cost of Prothrombin Complex Concentrate.

 

Comment

At my institution we recently revised our massive transfusion protocol to include PCCs rather than rVIIa. I must admit I was not familiar with PCCs, so after reading our new massive transfusion protocol I decided it was important for me to look up this new class of drug.

 

At our institution we use Kcentra which contains coagulation Factors II, VII, IX and X, and antithrombotic Proteins C and S as a lyophilized concentrate. Kcentra, Prothrombin Complex Concentrate (Human), is indicated for the urgent reversal of acquired coagulation factor deficiency induced by Vitamin K antagonist (e.g., warfarin) therapy in adult patients with acute major bleeding. The PCC used in this study, Profilnine SD, contains Factors II, VII (low levels), IX, and X and is indicated for the prevention and control of bleeding in patients with Factor IX deficiency due to hemophilia B. Both are four-factor PCCs, except that Kcentra also includes proteins C and S. For massive transfusions (including obstetrics), assuming no contraindications, we give Tranexamic acid (TXA) early (1,000 mg then repeat with 2nd dose in 30 minutes if needed) and then, if needed, administer Kcentra along with a 1:1:1 to 1.5:1:1 PRBC to FFP to Platelet ratio.

 

Similar to this study, we have found this protocol improves outcomes. The investigators in this study found that those who received PCC + FFP had a time to correction of INR almost 700 minutes faster than those who received FFP alone. This is rather impressive; however, because this study was retrospective, we cannot conclude that the combination of PCC + FFP alone caused the reduced time to correction of the INR. A limitation of this study is that the first two years of the control group time period did not include damage control resuscitation principles in the resuscitation. Additionally, the investigators did not report the volume of crystalloids administered. Therefore, these differences may have influenced the results. Nonetheless, I still think the findings of this study are important and reflect how our resuscitation protocols continue to evolve as new drugs come on the market.

 

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 2015 Anesthesia Abstracts · Volume 9 Number 6, June 30, 2015