Intraoperative Brain Activity Monitoring and Postanesthesia Care Unit Length of Stay: Results of a Systematic Review Dru Riddle, DNP, CRNA A systematic review represents the highest level of evidence to inform clinical practice and research. The results of this systematic review report on the impact of intraoperative brain activity monitoring on postanesthesia care unit length of stay. If used to guide anesthesia practice, the intraoperative brain activity monitor will have a statistically insignificant impact on reducing postanesthesia care unit length of stay. Clinicians should be aware, however, that there is a clinically useful reduction in postanesthesia care unit length of stay resulting in potential cost savings. Keywords: systematic review, brain monitoring, length of stay. Ó 2014 by American Society of PeriAnesthesia Nurses
THIS ARTICLE REPORTS A SYNOPSIS of a previously published systematic review completed by this author and published elsewhere.1 A highquality systematic review is based on an a priori protocol, much like a primary research protocol, that outlines in great detail the proposed methods for conducting the review. The purpose of this systematic review was to help give clarity to the impact of intraoperative brain activity monitoring (IBM) on the length of stay in the postanesthesia care unit (PACU). The use of intraoperative brain activity monitoring (BIS, Covidien, and others) has become commonplace in anesthesia practice over the past 15 years.2
reduction in intraoperative awareness, decreased postoperative pain, and increased patient satisfaction.4,5 The impact of IBM and PACU length of stay, however, was varied and sparse in the literature.3,6 There were contradictory studies reporting varying outcomes related to PACU length of stay, so a systematic review was undertaken to help better understand the impact of IBM on PACU length of stay. The purpose of the systematic review was to synthesize the best available evidence related to the use of IBM and PACU length of stay; it was hoped at the outset of the review that a meta-analysis of quantitative data could be performed to inform clinical practice.
Initially thought of only as an awareness monitor, the utility of the IBM technology has gone far beyond this sole purpose.3 There are several advantages purported to the use of IBM including
Objectives/Criteria
Dru Riddle, DNP, CRNA, Assistant Professor of Professional Practice, Texas Christian University, School of Nurse Anesthesia, TCU Box 298626, Fort Worth, TX. Conflict of interest: None to report. Address correspondence to Dru Riddle, Texas Christian University, School of Nurse Anesthesia, TCU Box 298626, Fort Worth, TX 76108; e-mail address: [email protected]. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.07.010
The objective of this systematic review was to synthesize the best available evidence on the effects of IBM on PACU length of stay.1 Based on the systematic review protocol, randomized control trials (RCTs) were initially sought to inform this phenomenon.7 In the absence of RCTs, other research trials were considered realizing that not all clinical questions can be answered with the RCT. Inclusion criteria were articles reporting on patients over the age of 8 years having received general anesthesia for any type of surgical or medical procedure. Exclusion criteria included patients bypassing the
Journal of PeriAnesthesia Nursing, Vol 29, No 6 (December), 2014: pp 475-479
475
DRU RIDDLE
476
traditional phase I recovery area (direct Intensive Care Unit Admission) and patients less than 8 years of age. Ultimately, several RCTs of high methodological quality were found; so this review only considered the RCT in the final data analysis.1
Methods A three-step search strategy was used aimed at finding all published and unpublished studies from January 1990 to May 2010 related to IBM and PACU length of stay.1 The date limiter of 1990 was placed on the search strategy because the use of IBM was not widely used before 1990.2 First, a key word search in two key databases (CINAHL and MEDLINE) was used to identify index terms and additional key words. Next, a comprehensive search of PUBMED, Embase, ScienceDirect, and ProQuest was undertaken. Finally, Google Scholar and MEDNAR were searched in an attempt to find unpublished studies, theses, and dissertation reports. For completeness, the reference list of all identified studies was hand searched to identify any article not previously found.1 The importance of searching the reference list of all retrieved studies cannot be understated as often keyword searches alone do not capture all published literature on a topic. A total of 488 potential manuscripts were identified in the search with 21 studies meeting inclusion criteria.1 After two independent reviewers critically appraised the quality of these 21 studies using the Joanna Briggs Institute Meta-analysis of Statistics Assessment and Review (JBI-MAStARI) quality appraisal tool, nine manuscripts were deemed of high enough methodological quality for inclusion in the meta-analysis and systematic review.1 It is important to assess the studies for methodological quality as not all published manuscripts report on high-quality research. All included manuscripts were RCTs. See Figure 1 for a flowchart of the search process. Data that were extracted from the nine included manuscripts using the Joanna Briggs Institute standardized data extraction tool found within the JBIMAStARI software suite. The same data extraction tool was used for all the included manuscripts to minimize errors in data extraction. The outcome of concern was PACU length of stay so only those data related to the length of stay in the recovery
room were extracted in minutes of length of stay in the PACU.
Data Analysis A total of nine studies were included in the metaanalysis. These nine studies reported on a total of 2,694 patients. The studies were international in nature, with one having been performed in Turkey, one in Germany, one in Canada, and the rest in the United States.1 The studies in Turkey, Germany, and two US studies were multicenter studies.1 The participants in all the studies were over the age of 17 years, and all had received general anesthesia for a wide variety of surgical procedures.1 Comparing demographic characteristics between studies, there were no differences found. All studies reported a comparison between a treatment group that received IBM and a control group that was considered standard of care without the use of IBM.1 The cohort of studies in this systematic review represents a cadre of 2,694 patients having received general anesthesia.1 In comparing the demographic characteristics of various patients, all were similar in age, gender, and American Society of Anesthesiologist classification with similar treatment and control groups. Patients had received general anesthesia for a variety of surgical procedures including orthopedic procedures, gynecological procedures, and urological procedures. One study only examined laparoscopic tubal ligation procedures.1 The number of patients in each study ranged from 40 to over 1,500, and all were RCTs. Data extracted from the included studies were analyzed using the JBI-MAStARI meta-analysis analytic module. Calculations for heterogeneity including chi-square and I-square were performed and ultimately, a moderate amount of statistical heterogeneity was shown in the data (chi-square, 25.29; P , .004; I-square, 68%).1 In a fundamental approach to meta-analyses, it would be inappropriate to combine results of these diverse studies considering the degree of heterogeneity seen in the data. However, in a JBI systematic review, the goal is to generate clinically useful information by combining results of individual studies into an aggregate of knowledge designed to answer questions broader than the individual studies alone. Because some degree of heterogeneity is expected in pooled data, and recognizing differences
RESULTS OF A SYSTEMATIC REVIEW
Figure 1. Flow chart of studies considered for inclusion in the systematic review.
477
478
between clinical and statistical heterogeneities, it was decided that performing a meta-analysis on the pooled data using a random effects model was appropriate and indicated in this situation.1,8 The decision to perform a meta-analysis was based, in part, on the following considerations. The nature of the studies all looked at the same variable: use of brain activity monitoring versus a control group in influencing PACU discharge time. Second, the quality of the studies was exceedingly high, and although the participants varied between studies, the administration of general anesthesia for surgical procedures was the same among all studies. Third, some degree of heterogeneity is expected in a treatment-oriented systematic review because of the very nature of the review incorporating multiple studies of varying clinical settings.1 A DerSimoniam and Laird weighted mean difference was calculated at the 95% confidence interval using a random effects model. It was determined that a statistically insignificant 3.48 minute (P 5 .14) reduction in PACU length of stay may be realized if IBM is used intra-operatively. A random effects model was chosen as the statistical method for calculating the weighted mean difference because of the degree of heterogeneity seen in the data. A random effects model allows for assumption that the true treatment effects between studies may differ from each other.1 See Figure 2 for a forest plot of the meta-analysis.
Discussion Recognizing that pooled statistical data are just one aspect of clinical applicability of findings
DRU RIDDLE
helps to interpret the results of this systematic review. Clinical and statistical significances vary greatly, and although applicability of statistically insignificant findings should be viewed with caution, they can be impactful on clinical decisions. This review indicates no statistically significant reduction in PACU length of stay when the IBM technology is used; however, there was a demonstrated 3.48-minute reduction in the PACU length of stay. Some would argue that because this is not statistically significant, no attention should be paid to the findings. Another argument looks at a broader picture of the review and these findings from a clinical perspective. In most PACUs, time is of the essence with the burden of patient flow, acuity, and staffing issues. A 3.48minute reduction in stay multiplied by the number of potential patients in a day, week, or even year yields a large number of patient care hours reduced. Although this systematic review is not one of cost effectiveness, current health care practice mandates a cost conscious approach to patient care. In this light, examining the impact of a 3.48minute reduction on PACU length of stay is warranted and was performed in the systematic review. This is not a formal cost effectiveness or cost benefit analysis but rather a crude calculation based on accepted cost of care in the United States. Estimating an average of $8.00 (USD) per minute of PACU time in an average community hospital in the United States, a 3.48-minute reduction in PACU length of stay could result in a $27.76 (USD) per patient cost savings. Using an average of 7,500 annual surgical cases, this extrapolates to a $208,200 (USD) annual savings.7 In addition,
Figure 2. Forest plot of meta-analysis results showing no statistically significant reduction in postanesthesia care unit length of stay when the intraoperative brain activity monitor technology is used.
RESULTS OF A SYSTEMATIC REVIEW
479
assuming a 3.48-minute reduction in nursing care per patient, the PACU can realize a 26,025 minute reduction in nursing work minutes or 433.75 hours annually.1 Experienced PACU nurses realize there are innumerable factors that impact a patient’s length of stay in the recovery room. Pain, nausea, staff availability in the receiving area, and acuity are just a few of the many reasons a patient might not be discharged from the PACU. Realizing that the use of IBM has the potential to impact the PACU length of stay holds promise for future research. Implications include targeted intraoperative anesthesia levels that result in an expedited PACU discharge as well as studies aimed at comparing anesthesia technique, IBM values, and PACU length of stay.
Conclusion This is one example of a systematic review and how it can be applied in clinical practice. There are numerous ways in which the findings can be applied in the clinical setting. Realizing that the outcome of interest was PACU length of stay, a potentially better way of asking this question is framed as PACU readiness for discharge. Several of the studies spoke to this readiness for discharge; however, none reported the time of readiness. The
time to readiness of discharge is a somewhat subjective measure with various scales and tools used to determine readiness. This could impose complex heterogeneity into the meta-analysis or preclude the performance of the meta-analysis all together. Realizing that the patient may be ready for discharge much sooner than actual patient discharge is important as one interprets the findings of this systematic review.
From these findings, the clinician can see that although statistically insignificant, length of stay in the PACU can be reduced slightly when IBM is used to help guide anesthesia delivery. Further research, both primary and translational, is needed to determine the optimum depth of anesthesia necessary to produce shortened PACU lengths of stay. The depth of anesthesia; dose of medications used to maintain the patient in a safe, properly, anesthetized state; and provider technique all have the potential to impact how long a patient remains in the PACU. Research teasing out each of these factors is needed to further quantify and predict length of PACU stay. Additionally, further research is needed to determine if anesthetic technique (eg, general anesthesia, total intravenous anesthesia has an impact on PACU length of stay.
References 1. Riddle D, Nugent H. Intraoperative brain activity monitoring and post-anesthesia care length of stay: A systematic review. JBI Database Syst Rev Implement Rep. 2011;9: 1971-1998. 2. Johansen JW. Update on bispectral index monitoring. Best Pract Res Clin Anaesthesiol. 2006;20:81-99. 3. Bruhn J, Kreuer S, Bischoff P, et al. Bispectral index and Aline AAI index as guidance for desflurane-remifentanil anaesthesia compared with a standard practice group: A multicentre study. Br J Anaesth. 2005;94:63-69. 4. Sandin RH, Enlund G, Samuelsson P, Lennmarken C. Awareness during anaesthesia: A prospective case study. Lancet. 2000; 355:707-711.
5. Myles PS, Leslie K, McNeil J, Forbes A, Chan MTV. Bispectral index monitoring to prevent awareness during anaesthesia: The B-Aware randomised controlled trial. Lancet. 2004;363: 1757-1763. 6. Boztug N, Bigat Z, Akyuz M, Demir S, Ertok E. Does using the bispectral index (BIS) during craniotomy affect the quality of recovery? J Neurosurg Anesthesiol. 2006;18:1-4. 7. Riddle D, Nugent H. The effects of intraoperative brain activity monitoring on post-anesthesia care unit length of stay: A systematic review. JBI Database Syst Rev Implement Rep. 2010;8(34 Suppl):S283-S292. 8. Higgins J, Thompson S, Deeks J, Altman D. Measuring inconsistency in meta-analysis. BMJ. 2003;327:557-560.
THIS ARTICLE REPORTS A SYNOPSIS of a previously published systematic review completed by this author and published elsewhere.1 A highquality systematic review is based on an a priori protocol, much like a primary research protocol, that outlines in great detail the proposed methods for conducting the review. The purpose of this systematic review was to help give clarity to the impact of intraoperative brain activity monitoring (IBM) on the length of stay in the postanesthesia care unit (PACU). The use of intraoperative brain activity monitoring (BIS, Covidien, and others) has become commonplace in anesthesia practice over the past 15 years.2
reduction in intraoperative awareness, decreased postoperative pain, and increased patient satisfaction.4,5 The impact of IBM and PACU length of stay, however, was varied and sparse in the literature.3,6 There were contradictory studies reporting varying outcomes related to PACU length of stay, so a systematic review was undertaken to help better understand the impact of IBM on PACU length of stay. The purpose of the systematic review was to synthesize the best available evidence related to the use of IBM and PACU length of stay; it was hoped at the outset of the review that a meta-analysis of quantitative data could be performed to inform clinical practice.
Initially thought of only as an awareness monitor, the utility of the IBM technology has gone far beyond this sole purpose.3 There are several advantages purported to the use of IBM including
Objectives/Criteria
Dru Riddle, DNP, CRNA, Assistant Professor of Professional Practice, Texas Christian University, School of Nurse Anesthesia, TCU Box 298626, Fort Worth, TX. Conflict of interest: None to report. Address correspondence to Dru Riddle, Texas Christian University, School of Nurse Anesthesia, TCU Box 298626, Fort Worth, TX 76108; e-mail address: [email protected]. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.07.010
The objective of this systematic review was to synthesize the best available evidence on the effects of IBM on PACU length of stay.1 Based on the systematic review protocol, randomized control trials (RCTs) were initially sought to inform this phenomenon.7 In the absence of RCTs, other research trials were considered realizing that not all clinical questions can be answered with the RCT. Inclusion criteria were articles reporting on patients over the age of 8 years having received general anesthesia for any type of surgical or medical procedure. Exclusion criteria included patients bypassing the
Journal of PeriAnesthesia Nursing, Vol 29, No 6 (December), 2014: pp 475-479
475
DRU RIDDLE
476
traditional phase I recovery area (direct Intensive Care Unit Admission) and patients less than 8 years of age. Ultimately, several RCTs of high methodological quality were found; so this review only considered the RCT in the final data analysis.1
Methods A three-step search strategy was used aimed at finding all published and unpublished studies from January 1990 to May 2010 related to IBM and PACU length of stay.1 The date limiter of 1990 was placed on the search strategy because the use of IBM was not widely used before 1990.2 First, a key word search in two key databases (CINAHL and MEDLINE) was used to identify index terms and additional key words. Next, a comprehensive search of PUBMED, Embase, ScienceDirect, and ProQuest was undertaken. Finally, Google Scholar and MEDNAR were searched in an attempt to find unpublished studies, theses, and dissertation reports. For completeness, the reference list of all identified studies was hand searched to identify any article not previously found.1 The importance of searching the reference list of all retrieved studies cannot be understated as often keyword searches alone do not capture all published literature on a topic. A total of 488 potential manuscripts were identified in the search with 21 studies meeting inclusion criteria.1 After two independent reviewers critically appraised the quality of these 21 studies using the Joanna Briggs Institute Meta-analysis of Statistics Assessment and Review (JBI-MAStARI) quality appraisal tool, nine manuscripts were deemed of high enough methodological quality for inclusion in the meta-analysis and systematic review.1 It is important to assess the studies for methodological quality as not all published manuscripts report on high-quality research. All included manuscripts were RCTs. See Figure 1 for a flowchart of the search process. Data that were extracted from the nine included manuscripts using the Joanna Briggs Institute standardized data extraction tool found within the JBIMAStARI software suite. The same data extraction tool was used for all the included manuscripts to minimize errors in data extraction. The outcome of concern was PACU length of stay so only those data related to the length of stay in the recovery
room were extracted in minutes of length of stay in the PACU.
Data Analysis A total of nine studies were included in the metaanalysis. These nine studies reported on a total of 2,694 patients. The studies were international in nature, with one having been performed in Turkey, one in Germany, one in Canada, and the rest in the United States.1 The studies in Turkey, Germany, and two US studies were multicenter studies.1 The participants in all the studies were over the age of 17 years, and all had received general anesthesia for a wide variety of surgical procedures.1 Comparing demographic characteristics between studies, there were no differences found. All studies reported a comparison between a treatment group that received IBM and a control group that was considered standard of care without the use of IBM.1 The cohort of studies in this systematic review represents a cadre of 2,694 patients having received general anesthesia.1 In comparing the demographic characteristics of various patients, all were similar in age, gender, and American Society of Anesthesiologist classification with similar treatment and control groups. Patients had received general anesthesia for a variety of surgical procedures including orthopedic procedures, gynecological procedures, and urological procedures. One study only examined laparoscopic tubal ligation procedures.1 The number of patients in each study ranged from 40 to over 1,500, and all were RCTs. Data extracted from the included studies were analyzed using the JBI-MAStARI meta-analysis analytic module. Calculations for heterogeneity including chi-square and I-square were performed and ultimately, a moderate amount of statistical heterogeneity was shown in the data (chi-square, 25.29; P , .004; I-square, 68%).1 In a fundamental approach to meta-analyses, it would be inappropriate to combine results of these diverse studies considering the degree of heterogeneity seen in the data. However, in a JBI systematic review, the goal is to generate clinically useful information by combining results of individual studies into an aggregate of knowledge designed to answer questions broader than the individual studies alone. Because some degree of heterogeneity is expected in pooled data, and recognizing differences
RESULTS OF A SYSTEMATIC REVIEW
Figure 1. Flow chart of studies considered for inclusion in the systematic review.
477
478
between clinical and statistical heterogeneities, it was decided that performing a meta-analysis on the pooled data using a random effects model was appropriate and indicated in this situation.1,8 The decision to perform a meta-analysis was based, in part, on the following considerations. The nature of the studies all looked at the same variable: use of brain activity monitoring versus a control group in influencing PACU discharge time. Second, the quality of the studies was exceedingly high, and although the participants varied between studies, the administration of general anesthesia for surgical procedures was the same among all studies. Third, some degree of heterogeneity is expected in a treatment-oriented systematic review because of the very nature of the review incorporating multiple studies of varying clinical settings.1 A DerSimoniam and Laird weighted mean difference was calculated at the 95% confidence interval using a random effects model. It was determined that a statistically insignificant 3.48 minute (P 5 .14) reduction in PACU length of stay may be realized if IBM is used intra-operatively. A random effects model was chosen as the statistical method for calculating the weighted mean difference because of the degree of heterogeneity seen in the data. A random effects model allows for assumption that the true treatment effects between studies may differ from each other.1 See Figure 2 for a forest plot of the meta-analysis.
Discussion Recognizing that pooled statistical data are just one aspect of clinical applicability of findings
DRU RIDDLE
helps to interpret the results of this systematic review. Clinical and statistical significances vary greatly, and although applicability of statistically insignificant findings should be viewed with caution, they can be impactful on clinical decisions. This review indicates no statistically significant reduction in PACU length of stay when the IBM technology is used; however, there was a demonstrated 3.48-minute reduction in the PACU length of stay. Some would argue that because this is not statistically significant, no attention should be paid to the findings. Another argument looks at a broader picture of the review and these findings from a clinical perspective. In most PACUs, time is of the essence with the burden of patient flow, acuity, and staffing issues. A 3.48minute reduction in stay multiplied by the number of potential patients in a day, week, or even year yields a large number of patient care hours reduced. Although this systematic review is not one of cost effectiveness, current health care practice mandates a cost conscious approach to patient care. In this light, examining the impact of a 3.48minute reduction on PACU length of stay is warranted and was performed in the systematic review. This is not a formal cost effectiveness or cost benefit analysis but rather a crude calculation based on accepted cost of care in the United States. Estimating an average of $8.00 (USD) per minute of PACU time in an average community hospital in the United States, a 3.48-minute reduction in PACU length of stay could result in a $27.76 (USD) per patient cost savings. Using an average of 7,500 annual surgical cases, this extrapolates to a $208,200 (USD) annual savings.7 In addition,
Figure 2. Forest plot of meta-analysis results showing no statistically significant reduction in postanesthesia care unit length of stay when the intraoperative brain activity monitor technology is used.
RESULTS OF A SYSTEMATIC REVIEW
479
assuming a 3.48-minute reduction in nursing care per patient, the PACU can realize a 26,025 minute reduction in nursing work minutes or 433.75 hours annually.1 Experienced PACU nurses realize there are innumerable factors that impact a patient’s length of stay in the recovery room. Pain, nausea, staff availability in the receiving area, and acuity are just a few of the many reasons a patient might not be discharged from the PACU. Realizing that the use of IBM has the potential to impact the PACU length of stay holds promise for future research. Implications include targeted intraoperative anesthesia levels that result in an expedited PACU discharge as well as studies aimed at comparing anesthesia technique, IBM values, and PACU length of stay.
Conclusion This is one example of a systematic review and how it can be applied in clinical practice. There are numerous ways in which the findings can be applied in the clinical setting. Realizing that the outcome of interest was PACU length of stay, a potentially better way of asking this question is framed as PACU readiness for discharge. Several of the studies spoke to this readiness for discharge; however, none reported the time of readiness. The
time to readiness of discharge is a somewhat subjective measure with various scales and tools used to determine readiness. This could impose complex heterogeneity into the meta-analysis or preclude the performance of the meta-analysis all together. Realizing that the patient may be ready for discharge much sooner than actual patient discharge is important as one interprets the findings of this systematic review.
From these findings, the clinician can see that although statistically insignificant, length of stay in the PACU can be reduced slightly when IBM is used to help guide anesthesia delivery. Further research, both primary and translational, is needed to determine the optimum depth of anesthesia necessary to produce shortened PACU lengths of stay. The depth of anesthesia; dose of medications used to maintain the patient in a safe, properly, anesthetized state; and provider technique all have the potential to impact how long a patient remains in the PACU. Research teasing out each of these factors is needed to further quantify and predict length of PACU stay. Additionally, further research is needed to determine if anesthetic technique (eg, general anesthesia, total intravenous anesthesia has an impact on PACU length of stay.
References 1. Riddle D, Nugent H. Intraoperative brain activity monitoring and post-anesthesia care length of stay: A systematic review. JBI Database Syst Rev Implement Rep. 2011;9: 1971-1998. 2. Johansen JW. Update on bispectral index monitoring. Best Pract Res Clin Anaesthesiol. 2006;20:81-99. 3. Bruhn J, Kreuer S, Bischoff P, et al. Bispectral index and Aline AAI index as guidance for desflurane-remifentanil anaesthesia compared with a standard practice group: A multicentre study. Br J Anaesth. 2005;94:63-69. 4. Sandin RH, Enlund G, Samuelsson P, Lennmarken C. Awareness during anaesthesia: A prospective case study. Lancet. 2000; 355:707-711.
5. Myles PS, Leslie K, McNeil J, Forbes A, Chan MTV. Bispectral index monitoring to prevent awareness during anaesthesia: The B-Aware randomised controlled trial. Lancet. 2004;363: 1757-1763. 6. Boztug N, Bigat Z, Akyuz M, Demir S, Ertok E. Does using the bispectral index (BIS) during craniotomy affect the quality of recovery? J Neurosurg Anesthesiol. 2006;18:1-4. 7. Riddle D, Nugent H. The effects of intraoperative brain activity monitoring on post-anesthesia care unit length of stay: A systematic review. JBI Database Syst Rev Implement Rep. 2010;8(34 Suppl):S283-S292. 8. Higgins J, Thompson S, Deeks J, Altman D. Measuring inconsistency in meta-analysis. BMJ. 2003;327:557-560.
