Dig Dis Sci DOI 10.1007/s10620-014-3118-2
ORIGINAL ARTICLE
Monitored Anesthesia Care Without Endotracheal Intubation Is Safe and Efficacious for Single-Balloon Enteroscopy Saurabh Sethi • Adarsh M. Thaker • Jonah Cohen • Sagar Garud Mandeep S. Sawhney • Ram Chuttani • Douglas K. Pleskow • Sheila R. Barnett • Tyler M. Berzin
•
Received: 22 November 2013 / Accepted: 13 March 2014 Ó Springer Science+Business Media New York 2014
Abstract Background General endotracheal (GET) anesthesia is often used during single-balloon enteroscopy (SBE). However, there is currently limited data regarding monitored anesthesia care (MAC) without endotracheal intubation for this procedure. Aims The aim of the study was to determine the safety and efficacy of MAC sedation during SBE and to identify risk factors for adverse events. Methods All patients who underwent SBE and SBEassisted endoscopic retrograde cholangiopancreatography between June 2011 and July 2013 at a tertiary-care referral center were studied in a retrospective analysis of a prospectively collected database. Patients received MAC anesthesia or GET. The main outcome measurements were sedation-related adverse events, diagnostic yield, and therapeutic yield.
Results Of the 178 cases in the study, 166 cases (93 %) were performed with MAC and 12 (7 %) with GET. Intraprocedure sedation-related adverse events occurred in 17 % of cases. The most frequent event was transient hypotension requiring pharmacologic intervention in 11.8 % of procedures. In MAC cases, the diagnostic yield was 58.4 % and the therapeutic yield was 30.1 %. Anesthesia duration was strongly associated with the occurrence of a sedation-related adverse event (P = 0.005). Conclusions MAC is a safe and efficacious sedation approach for most patients undergoing SBE. Sedationrelated complications in SBE are uncommon, but are more frequent in longer procedures. Keywords Single-balloon enteroscopy Monitored anesthesia care Small-bowel disease Outcomes
Saurabh Sethi and Adarsh M. Thaker are co-first authors. S. Sethi A. M. Thaker J. Cohen S. Garud M. S. Sawhney R. Chuttani D. K. Pleskow T. M. Berzin (&) Division of Gastroenterology, Center for Advanced Endoscopy, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA e-mail: [email protected]
M. S. Sawhney e-mail: [email protected]
S. Sethi e-mail: [email protected]
S. R. Barnett Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA e-mail: [email protected]
A. M. Thaker e-mail: [email protected] J. Cohen e-mail: [email protected]
R. Chuttani e-mail: [email protected] D. K. Pleskow e-mail: [email protected]
S. Garud e-mail: [email protected]
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Background The advent of overtube-assisted deep enteroscopy techniques such as single-balloon enteroscopy (SBE) has allowed gastroenterologists to reach segments of the small bowel previously beyond the limits of a standard enteroscope. Deeper investigation of the bowel may result in increased procedure time, and some reports have described average SBE durations as long as 96 min [1]. This exposes patients to longer periods of sedation, potentially increasing the risk from a sedation-related adverse event (SRAE). While most routine endoscopic procedures such as EGD and colonoscopy are performed under nurse-administered moderate sedation directed by the gastroenterologist, advanced endoscopic procedures are increasingly being performed under anesthesiologist-directed monitored anesthesia care (MAC) [2, 3]. A major advantage of anesthesiologist-directed sedation is the ability to achieve a deeper level of sedation and faster onset and recovery times compared to nursing moderate sedation [4–6]. Although previous studies have demonstrated the safety and efficacy of MAC in ERCP, endoscopic ultrasound (EUS), and double-balloon enteroscopy (DBE), there is currently limited evidence regarding the safety and efficacy of MAC for SBE [7–13]. One recent report on a combination of procedures including SBE, push enteroscopy, and spiral enteroscopy showed a relatively high rate (49.4 %) of anesthesia-related complications, primarily cardiovascular in nature, including transient hypotension [13]. However, about half of the patients in this study received general anesthesia with endotracheal intubation (GET) [13]. At our institution, which includes a large advanced endoscopy referral practice, MAC anesthesia is used preferentially for the majority of advanced endoscopy procedures, including SBE. The aim of this study was to assess sedation-related adverse events (SRAEs) during SBE in patients undergoing anesthesiologist-administered sedation via MAC, as well as to identify risk factors associated with SRAEs. We also sought to describe the diagnostic and therapeutic yield of SBE when using MAC.
Methods Study Population All patients who underwent SBE, including single-balloonassisted ERCP, at Beth Israel Deaconess Medical Center in Boston, Massachusetts, from June 2011 to July 2013 were included in the study. In all cases either MAC or GET, anesthesia was administered by an anesthesiologist. GET was defined as general anesthesia with endotracheal
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intubation, and MAC was defined as all other sedation. Choice of anesthesia approach (MAC or GET) was determined by the anesthesiologist in collaboration with the endoscopy team. Indications for GET generally include morbid obesity, higher American Society of Anesthesiologists (ASA) physical status classification (including cardiopulmonary instability), significant pain (e.g., from recent surgery and ongoing pain medication requirements), or significant risk of aspiration (e.g., impaired neurologic function, full stomach, or intestinal obstruction). During the study period, 187 SBEs were performed. Nine cases were excluded from the study due to insufficient data. The population characteristics and indications for SBE are shown in Table 1. Data Collection Before SBE, all patients underwent a standard pre-anesthesia assessment by a member of the anesthesiology team. Each patient was assigned an American Society of Anesthesiologists (ASA) physical status classification based on the pre-procedure evaluation. Pre-procedure and intraprocedural data were collected via an automated anesthesia electronic record. This included vital signs, administered medications, and anesthesia-related events or interventions. The time of induction of anesthesia, the time of initiation of the endoscopy, the time of completion of the procedure, and the time of completion of anesthesia were recorded by the anesthesiology team. Definition of Sedation-Related Adverse Events Intra-procedure SRAEs were defined as hypoxia (O2 saturation \85 %) of any duration, unplanned endotracheal intubation, hypotension (systolic blood pressure [SBP] \90 mmHg) requiring use of vasopressor medications, cardiac arrhythmias (heart rate [HR][120 or\60 beats per minute) requiring treatment, or premature termination of endoscopy due to a sedation-related event. Treatment of hypotension with vasopressors occurred if the anesthesiologist determined that the patient’s hypotension (SBP \90 mmHg) was clinically significant and would be inadequately treated by intravenous fluids alone. Treatment of tachycardia (HR [120) and bradycardia (HR \60) also occurred at the discretion of the anesthesiologist if determined to be clinically significant. Variables and Data Analysis Based on review of available literature, we specified the following predictor variables for sedation-related complications a priori: age, gender, ASA class, body mass index (BMI), medications used for sedation, and comorbidities
Dig Dis Sci Table 1 Patient demographic information and procedure indications Variable
No., n = 178
% of total patients
Gender Male
97
54.5
Female
81
45.5
Medical comorbiditiesa Congestive heart failure
25
14.4
Coronary artery disease
38
21.4
Hypertension Asthma
91 24
51.1 13.5
COPD
30
16.9
GERD
108
60.7
57
32.0
Malignancy Chronic kidney disease
25
14.0
Obesity (BMI C30)
59
33.1
Average BMI (kg/m2)
28.23
–
ASA risk class I
0
0
II
47
26.3
III
119
66.5
IV
12
6.7
Anemia
84
47.2
Overt GI bleeding Occult GI bleeding
55 40
30.9 22.5
Suspected IBD
10
5.6
Fig. 1 Sedatives used for SBE for MAC and GET. MAC monitored anesthesia care, GET general endotracheal anesthesia
using categorical variables. Mann–Whitney U test was used when comparing two groups using continuous variables. A P value \0.05 was considered statistically significant. Logistic regression analysis was used to assess the association between patient, procedure, and anesthesiarelated variables and adverse events.
Procedure indicationsa
Suspected mass
46
25.8
Abdominal pain
45
25.3
Nausea or vomiting
16
9.0
Weight loss
6
3.4
Foreign body (including stents)
5
2.8
Diarrhea
6
3.4
Suspected stone
1
0.6
Jaundice
2
1.1
COPD chronic obstructive pulmonary disease, GERD gastroesophageal reflux disease, BMI body mass index, ASA American Society of Anesthesiologists, GI gastrointestinal, IBD inflammatory bowel disease a
Non-exclusive
including congestive heart failure (CHF), coronary artery disease (CAD), hypertension, asthma, chronic obstructive pulmonary disease (COPD), gastroesophageal reflux disease (GERD), malignancy, chronic kidney disease, and obesity (defined as a body mass index greater than or equal to 30 at time of procedure) [7, 12, 14–17]. BMI was used as a continuous variable as well as to define obesity as a discrete comorbidity. SPSS version 17.0 (IBM) was used for statistical analysis. Chi-squared test was used when comparing groups
Results Patient and Procedure Characteristics In the final study group, 178 SBEs were performed on a total of 155 patients for suspected small-bowel or biliary disease. Sixteen patients underwent more than one SBE. Seventeen cases were SBE-assisted ERCPs. The mean age of study patients was 63.0 ± 14.4 years (range 19–92 years), and 45.5 % were women. Many patients had more than one indication for an SBE as shown in Table 1. Initial choice of anesthesia was MAC in 166 cases (93.3 %) and GET in 12 cases (6.7 %). The most commonly used sedative medication (Fig. 1) was propofol (97.8 % of all cases), followed by midazolam (55.1 %), ketamine (44.9 %), and fentanyl (9.6 %). Most patients received a combination of two or more of these medications. Peroral approach was used in 157 cases, of which 147 were performed with MAC, and a bidirectional approach was used in 10 cases, of which nine were performed with MAC. The average procedure duration (determined by time from endoscope insertion to removal) was 48.8 ± 17.8 min. Procedure duration for the cases that required conversion from MAC to GET included the time the procedure was paused in order to intubate. The average anesthesia duration, defined as induction of anesthesia to end of anesthesia, was 61.8 ± 18.6 min, overall.
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Fig. 2 Number of events in procedures using MAC or GET. MAC monitored anesthesia care, GET general endotracheal anesthesia
Fig. 3 Diagnostic and therapeutic yields for procedures using MAC (n = 166) and GET (n = 12). MAC monitored anesthesia care, GET general endotracheal anesthesia
Sedation-Related Adverse Events There were a total of 32 intra-procedure SRAEs occurring in 30 (17 %) of the 178 procedures and 26 (15.8 %) of the 166 MAC procedures (Fig. 2). Intra-procedure respiratory events included hypoxia, three events (1.7 % of procedures); mask ventilation, one event (\1 %); and unplanned endotracheal intubation, three events (1.7 %). Intra-procedure cardiovascular or hemodynamic events included transient hypotension to SBP \90 requiring vasopressor use, 21 events (11.8 %), and tachy- or brady-arrhythmia requiring treatment, two events (1.1 %). There were no intra-procedure cardiac arrests or deaths. Premature procedure termination related to sedation occurred in two patients (1.1 %) under MAC anesthesia. In one patient, this was due to acute shortness of breath following the initial administration of midazolam. In the second patient, subcutaneous emphysema of the face and neck developed approximately 30 min into the procedure. This outcome was suggestive of airway injury from a difficult to place nasopharyngeal airway device verses a small, self-contained esophageal or posterior pharyngeal perforation which were seen neither on endoscope withdrawal nor on barium studies. The subcutaneous emphysema resolved with conservative management, and the patient was discharged several days later in stable condition. Three additional cases required intra-procedure conversion from MAC to GET, one due to inadequate sedation, one for airway protection in the setting of food, and the third due to difficult oxygenation. The SBE procedure was ultimately completed successfully in all three patients under GET. Interventions and Yields A total of 188 endoscopic interventions were performed in 129 of the 178 SBEs. These included tattooing of the bowel
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wall in 62 of the 178 cases (34.8 %). Biopsies were taken in 60 cases (33.7 %). Interventions to achieve hemostasis were performed in 39 cases (21.9 %). Additional endoscopic therapies included polypectomy in five cases (2.8 %), foreign body removal in five cases (2.8 %). Stricture dilation, sphincterotomy, sphincteroplasty, and biliary stenting were each performed once (\1 %). A diagnosis was made in 105 cases (diagnostic yield = 59 %), and a therapeutic intervention was performed in 54 cases (therapeutic yield = 30 %). Separate yields for MAC and GET sedation are shown in Fig. 3. A diagnosis was made in 97 of the 166 MAC cases (58.4 %) and 8 of the 12 GET cases (66.7 %). Therapeutic intervention was performed in 50 MAC cases (30.1 %) and 4 GET cases (33.3 %).
Regression Analysis Univariate logistic regression was performed to assess associations between predictor variables and SRAEs (Tables 2, 3) for all cases. Of these variables, only anesthesia duration and procedure duration were associated with adverse events (odds ratio [OR] 1.04; P \ 0.001 and OR 1.03; P = 0.003, respectively). A multivariate logistic regression model was created using SRAEs as the outcome variable (Table 4). The predictor variables with a P value of \0.1 on univariate analysis (anesthesia duration and procedure duration) were entered into the model. On multivariate analysis, anesthesia duration (OR 1.07, P = 0.005) was significantly associated with adverse events while procedure duration (P = 0.243) was no longer statistically significant. We also created separate univariate regression models for respiratory events and cardiovascular events. Here, the duration of anesthesia was strongly associated with
Dig Dis Sci Table 2 Univariate analysis of factors associated with intra-procedure sedation-related events Variable
Odds ratio
Confidence interval
P value
Age (years)
1.02
0.991–1.05
0.169
Sex (male) ASA class, I, II, III, IV
1.112 1.3
0.504–2.452 0.625–2.702
0.793 0.483
BMI (kg/m2)a
1.031
0.965–1.101
0.362
Anesthesia duration (mina)
Propofol (binary)
0.6
0.060–5.973
0.663
a
Ketamine (binary)
0.557
0.244–1.271
0.165
Midazolam (binary)
0.667
0.303–1.465
0.313
Fentanyl (binary)
Patient characteristics
Medication use
1.063
0.286–3.956
0.927
Procedure duration (min)
1.033
1.011–1.055
0.003
Anesthesia duration (min)
1.043
1.021–1.065
\0.001
BMI body mass index, ASA American Society of Anesthesiologists, SRAE sedation-related adverse event, min minutes a
Table 4 Multivariate analysis of factors associated with intra-procedure adverse events: adjusted odds ratios by logistic regression
Increase in risk of an SRAE for each additional kg/m2
Table 3 Univariate analysis of comorbid conditions associated with intra-procedure sedation-related events Comorbidity
Odds ratio
Confidence interval
P value
CHF
0.636
0.178–2.279
0.487
CAD
1.119
0.440–2.850
0.813
Hypertension
1.308
0.593–2.884
0.506
Asthma
0.672
0.187–2.414
0.542
COPD
0.722
0.232–2.245
0.573
GERD
1.145
0.508–2.580
0.744
Malignancy
1.526
0.679–3.430
0.307
CKD
1.526
0.178–2.279
0.487
Obesity (BMI C30)
0.719
0.320–1.615
0.425
CAD coronary artery disease, COPD chronic obstructive pulmonary disease, GERD gastroesophageal reflux disease, CKD chronic kidney disease, BMI body mass index
Procedure duration (mina)
Coefficient
Standard error
OR
95 % CI
P value
-0.028
0.024
0.972
0.93–1.02
0.234
0.066
0.023
1.068
1.02–1.12
0.005
OR odds ratio, CI confidence interval, min minutes Increase in risk of SRAE for each additional minute
trended toward significance (P = 0.079). For cardiovascular SRAEs, the model included age (P = 0.096 on univariate analysis) in addition to anesthesia duration and procedure duration. However, these did not remain statistically significant on multivariate analysis (P = 0.176, P = 0.229, and P = 0.786, respectively). The univariate and multivariate analyses were also conducted specifically on the 166 cases performed with MAC. In univariate analysis, procedure duration (P = 0.012) and anesthesia duration (P = 0.001) were significantly associated with the occurrence of an SRAE in MAC procedures. Only anesthesia duration remained significant (OR 1.05, P = 0.025) on multivariate analysis. When selecting for respiratory SRAEs in MAC cases, only anesthesia duration was significantly associated (P = 0.012) on univariate analysis. Selecting for cardiovascular SRAEs in MAC, both procedure duration (P = 0.001) and anesthesia duration (P = 0.007) were significant on univariate analysis. On multivariate analysis for these variables, procedure duration trended toward significance (OR 1.08, P = 0.054), while anesthesia duration was no longer significant.
Discussion respiratory SRAEs (P = 0.005) as well as for cardiovascular SRAEs (P \ 0.001). Duration of the endoscopic procedure was associated with cardiovascular events (P \ 0.001). Patient-related parameters, including increasing age, higher ASA class, and increasing BMI, as well as the listed medical comorbidities were not statistically associated with either respiratory or cardiovascular SRAEs (P [ 0.05). Multivariate analysis was again performed for predictor variables with a P value of \0.1. For respiratory SRAEs, this included anesthesia duration as well as past medical history of CAD (P = 0.061). Anesthesia time remained significant for respiratory SRAEs (P = 0.008), and CAD
This study demonstrates the safe and efficacious use of MAC sedation for SBE while also reporting the wide variety of indications and treatment options for which SBE is performed. The study also highlights that the procedure length inherently characteristic of SBE may increase the risk of adverse events. Monitored anesthesia care without endotracheal intubation is becoming increasingly common for advanced endoscopic procedures such as ERCP and EUS [18]; however, data regarding sedation for deep enteroscopy procedures such as SBE are limited. There is some information available regarding sedation in double-balloon enteroscopy (DBE), but a much greater percentage of
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patients in these studies received GET than our study [11, 19, 20]. One recent report which aimed to evaluate the safety of GET in 108 DBE cases described a relatively high frequency of hypotension (30.6 %), hypoxia (21.3 %), and apnea (17.6 %) [11]. However, as these were reversible complications treated by the anesthesiologist, their study still recommended GET for DBE as an alternative to conscious sedation [11]. Given that nurse-administered conscious sedation is inherently limited compared to MAC, it is not surprising that a GET was preferred in this study. In contrast, another report found no difference in overall complication rates in 214 DBEs, of which 40.2 % were performed under GET while the remaining patients received MAC [20]. In our study, most of the adverse events were minor; for example, 24 (13.5 % of all cases) of these events were transient hypotension or arrhythmia managed pharmacologically by the anesthesiologist without needing to interrupt the procedure. We also observed a lower rate of sedation-related adverse events (17 % of procedures) than previous reports evaluating deep enteroscopy, even though we included SBE-assisted ERCP, a technically complicated procedure, in the study group [21]. At our institution, all advanced endoscopy procedures are staffed by anesthesiologists, and they have therefore gained significant experience in these procedures. Their resulting expertise may contribute to our lower rate of SRAEs [18]. The relatively low complication rate also partially stems from the fact that we only considered adverse events (such as hypotension or arrhythmias) that were clinically significant requiring some type of pharmacologic anesthesiologist intervention, as opposed to all episodes when patients became transiently hypotensive, tachycardic, or bradycardic. Another study of anesthesia in advanced endoscopy, for example, defined hypotension or hypertension as any change in blood pressure [20 % from baseline, which resulted in 41 % of their cohort being described as having hypotension versus 11.8 % in our study [13]. This broad definition may not accurately reflect clinically significant adverse events. On the other hand, an 11.8 % rate of hypotension requiring vasopressor use is not insignificant. Decreases in systemic vascular resistance, cardiac output, and blood pressure are among the known pharmacologic effects of propofol, which was given alone or in combination with other sedatives to most patients in our study [3]. However, most periods of hypotension were brief, required only short infusions of vasopressor agents, and did not affect the overall success of the procedure. The observed frequency of hypotension is also within the range of prior studies regarding propofol-based sedation in ERCP, reported from 0.8 % up to 18.9 %, though data for SBE is limited [9, 12,
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14]. As propofol-based MAC is well established for other advanced endoscopy procedures, these findings together lead us to conclude that MAC sedation such as with propofol is safe for SBE as well and serves as a practical alternative to GET. We also sought to identify risk factors associated with sedation-related adverse events. We observed that duration of anesthesia was a strong and independent predictor for the occurrence of a sedation-related adverse event in SBE. Given that SBE is inherently a long procedure, the risk of even performing it must be considered, but can be weighed against the benefits of evaluating and possibly treating lesions deep in the small bowel otherwise outside of the reach of a standard enteroscope. Reassuringly, our study reveals that despite the duration, most patients tolerated the procedure with MAC sedation without major sedation-related complications. Further studies are required to identify patient-related risk factors and perhaps develop additional tools to predict adverse events, which may help guide choice of sedation. Regarding the efficacy of MAC in this study, very few cases required conversion from MAC to GET due to sedation. The overall diagnostic yield of SBE was 59 % and the overall therapeutic yield was 30 %. For the 166 procedures performed under MAC, the diagnostic yield was 58 % and the therapeutic yield was 30 %. These values are consistent with the findings of earlier studies [1, 22–25], implying that our use of predominately MAC sedation does not affect procedure outcomes and supports its wider use as an alternative to GET. A limitation of our study was the fact that the sedation approach was not randomized, constraining direct comparisons of MAC to GET. As GET is not routinely performed for SBE at our institution, the number of GET cases was small, which limited the conclusions that can be drawn about this sedation method. As such, patient characteristics comparing the MAC and GET groups were omitted. Additionally, this was a retrospective, single-center cohort. However, our database was created prospectively and is to our knowledge among the larger SBE cohorts published to date [1, 21–29]. Randomized controlled trials are needed to truly compare MAC to GET, but the results of this investigation support the widening role of MAC in advanced endoscopic procedures such as SBE. In summary, this work demonstrates that MAC is a safe and efficacious sedation approach for the majority of patients undergoing SBE. Conversion to GET was infrequently required in the MAC cases. Anesthesia-related complications were rare overall, and reducing the duration of anesthesia may decrease the risk of adverse events for patients undergoing SBE. Conflict of interest
None.
Dig Dis Sci
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ORIGINAL ARTICLE
Monitored Anesthesia Care Without Endotracheal Intubation Is Safe and Efficacious for Single-Balloon Enteroscopy Saurabh Sethi • Adarsh M. Thaker • Jonah Cohen • Sagar Garud Mandeep S. Sawhney • Ram Chuttani • Douglas K. Pleskow • Sheila R. Barnett • Tyler M. Berzin
•
Received: 22 November 2013 / Accepted: 13 March 2014 Ó Springer Science+Business Media New York 2014
Abstract Background General endotracheal (GET) anesthesia is often used during single-balloon enteroscopy (SBE). However, there is currently limited data regarding monitored anesthesia care (MAC) without endotracheal intubation for this procedure. Aims The aim of the study was to determine the safety and efficacy of MAC sedation during SBE and to identify risk factors for adverse events. Methods All patients who underwent SBE and SBEassisted endoscopic retrograde cholangiopancreatography between June 2011 and July 2013 at a tertiary-care referral center were studied in a retrospective analysis of a prospectively collected database. Patients received MAC anesthesia or GET. The main outcome measurements were sedation-related adverse events, diagnostic yield, and therapeutic yield.
Results Of the 178 cases in the study, 166 cases (93 %) were performed with MAC and 12 (7 %) with GET. Intraprocedure sedation-related adverse events occurred in 17 % of cases. The most frequent event was transient hypotension requiring pharmacologic intervention in 11.8 % of procedures. In MAC cases, the diagnostic yield was 58.4 % and the therapeutic yield was 30.1 %. Anesthesia duration was strongly associated with the occurrence of a sedation-related adverse event (P = 0.005). Conclusions MAC is a safe and efficacious sedation approach for most patients undergoing SBE. Sedationrelated complications in SBE are uncommon, but are more frequent in longer procedures. Keywords Single-balloon enteroscopy Monitored anesthesia care Small-bowel disease Outcomes
Saurabh Sethi and Adarsh M. Thaker are co-first authors. S. Sethi A. M. Thaker J. Cohen S. Garud M. S. Sawhney R. Chuttani D. K. Pleskow T. M. Berzin (&) Division of Gastroenterology, Center for Advanced Endoscopy, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA e-mail: [email protected]
M. S. Sawhney e-mail: [email protected]
S. Sethi e-mail: [email protected]
S. R. Barnett Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA e-mail: [email protected]
A. M. Thaker e-mail: [email protected] J. Cohen e-mail: [email protected]
R. Chuttani e-mail: [email protected] D. K. Pleskow e-mail: [email protected]
S. Garud e-mail: [email protected]
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Background The advent of overtube-assisted deep enteroscopy techniques such as single-balloon enteroscopy (SBE) has allowed gastroenterologists to reach segments of the small bowel previously beyond the limits of a standard enteroscope. Deeper investigation of the bowel may result in increased procedure time, and some reports have described average SBE durations as long as 96 min [1]. This exposes patients to longer periods of sedation, potentially increasing the risk from a sedation-related adverse event (SRAE). While most routine endoscopic procedures such as EGD and colonoscopy are performed under nurse-administered moderate sedation directed by the gastroenterologist, advanced endoscopic procedures are increasingly being performed under anesthesiologist-directed monitored anesthesia care (MAC) [2, 3]. A major advantage of anesthesiologist-directed sedation is the ability to achieve a deeper level of sedation and faster onset and recovery times compared to nursing moderate sedation [4–6]. Although previous studies have demonstrated the safety and efficacy of MAC in ERCP, endoscopic ultrasound (EUS), and double-balloon enteroscopy (DBE), there is currently limited evidence regarding the safety and efficacy of MAC for SBE [7–13]. One recent report on a combination of procedures including SBE, push enteroscopy, and spiral enteroscopy showed a relatively high rate (49.4 %) of anesthesia-related complications, primarily cardiovascular in nature, including transient hypotension [13]. However, about half of the patients in this study received general anesthesia with endotracheal intubation (GET) [13]. At our institution, which includes a large advanced endoscopy referral practice, MAC anesthesia is used preferentially for the majority of advanced endoscopy procedures, including SBE. The aim of this study was to assess sedation-related adverse events (SRAEs) during SBE in patients undergoing anesthesiologist-administered sedation via MAC, as well as to identify risk factors associated with SRAEs. We also sought to describe the diagnostic and therapeutic yield of SBE when using MAC.
Methods Study Population All patients who underwent SBE, including single-balloonassisted ERCP, at Beth Israel Deaconess Medical Center in Boston, Massachusetts, from June 2011 to July 2013 were included in the study. In all cases either MAC or GET, anesthesia was administered by an anesthesiologist. GET was defined as general anesthesia with endotracheal
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intubation, and MAC was defined as all other sedation. Choice of anesthesia approach (MAC or GET) was determined by the anesthesiologist in collaboration with the endoscopy team. Indications for GET generally include morbid obesity, higher American Society of Anesthesiologists (ASA) physical status classification (including cardiopulmonary instability), significant pain (e.g., from recent surgery and ongoing pain medication requirements), or significant risk of aspiration (e.g., impaired neurologic function, full stomach, or intestinal obstruction). During the study period, 187 SBEs were performed. Nine cases were excluded from the study due to insufficient data. The population characteristics and indications for SBE are shown in Table 1. Data Collection Before SBE, all patients underwent a standard pre-anesthesia assessment by a member of the anesthesiology team. Each patient was assigned an American Society of Anesthesiologists (ASA) physical status classification based on the pre-procedure evaluation. Pre-procedure and intraprocedural data were collected via an automated anesthesia electronic record. This included vital signs, administered medications, and anesthesia-related events or interventions. The time of induction of anesthesia, the time of initiation of the endoscopy, the time of completion of the procedure, and the time of completion of anesthesia were recorded by the anesthesiology team. Definition of Sedation-Related Adverse Events Intra-procedure SRAEs were defined as hypoxia (O2 saturation \85 %) of any duration, unplanned endotracheal intubation, hypotension (systolic blood pressure [SBP] \90 mmHg) requiring use of vasopressor medications, cardiac arrhythmias (heart rate [HR][120 or\60 beats per minute) requiring treatment, or premature termination of endoscopy due to a sedation-related event. Treatment of hypotension with vasopressors occurred if the anesthesiologist determined that the patient’s hypotension (SBP \90 mmHg) was clinically significant and would be inadequately treated by intravenous fluids alone. Treatment of tachycardia (HR [120) and bradycardia (HR \60) also occurred at the discretion of the anesthesiologist if determined to be clinically significant. Variables and Data Analysis Based on review of available literature, we specified the following predictor variables for sedation-related complications a priori: age, gender, ASA class, body mass index (BMI), medications used for sedation, and comorbidities
Dig Dis Sci Table 1 Patient demographic information and procedure indications Variable
No., n = 178
% of total patients
Gender Male
97
54.5
Female
81
45.5
Medical comorbiditiesa Congestive heart failure
25
14.4
Coronary artery disease
38
21.4
Hypertension Asthma
91 24
51.1 13.5
COPD
30
16.9
GERD
108
60.7
57
32.0
Malignancy Chronic kidney disease
25
14.0
Obesity (BMI C30)
59
33.1
Average BMI (kg/m2)
28.23
–
ASA risk class I
0
0
II
47
26.3
III
119
66.5
IV
12
6.7
Anemia
84
47.2
Overt GI bleeding Occult GI bleeding
55 40
30.9 22.5
Suspected IBD
10
5.6
Fig. 1 Sedatives used for SBE for MAC and GET. MAC monitored anesthesia care, GET general endotracheal anesthesia
using categorical variables. Mann–Whitney U test was used when comparing two groups using continuous variables. A P value \0.05 was considered statistically significant. Logistic regression analysis was used to assess the association between patient, procedure, and anesthesiarelated variables and adverse events.
Procedure indicationsa
Suspected mass
46
25.8
Abdominal pain
45
25.3
Nausea or vomiting
16
9.0
Weight loss
6
3.4
Foreign body (including stents)
5
2.8
Diarrhea
6
3.4
Suspected stone
1
0.6
Jaundice
2
1.1
COPD chronic obstructive pulmonary disease, GERD gastroesophageal reflux disease, BMI body mass index, ASA American Society of Anesthesiologists, GI gastrointestinal, IBD inflammatory bowel disease a
Non-exclusive
including congestive heart failure (CHF), coronary artery disease (CAD), hypertension, asthma, chronic obstructive pulmonary disease (COPD), gastroesophageal reflux disease (GERD), malignancy, chronic kidney disease, and obesity (defined as a body mass index greater than or equal to 30 at time of procedure) [7, 12, 14–17]. BMI was used as a continuous variable as well as to define obesity as a discrete comorbidity. SPSS version 17.0 (IBM) was used for statistical analysis. Chi-squared test was used when comparing groups
Results Patient and Procedure Characteristics In the final study group, 178 SBEs were performed on a total of 155 patients for suspected small-bowel or biliary disease. Sixteen patients underwent more than one SBE. Seventeen cases were SBE-assisted ERCPs. The mean age of study patients was 63.0 ± 14.4 years (range 19–92 years), and 45.5 % were women. Many patients had more than one indication for an SBE as shown in Table 1. Initial choice of anesthesia was MAC in 166 cases (93.3 %) and GET in 12 cases (6.7 %). The most commonly used sedative medication (Fig. 1) was propofol (97.8 % of all cases), followed by midazolam (55.1 %), ketamine (44.9 %), and fentanyl (9.6 %). Most patients received a combination of two or more of these medications. Peroral approach was used in 157 cases, of which 147 were performed with MAC, and a bidirectional approach was used in 10 cases, of which nine were performed with MAC. The average procedure duration (determined by time from endoscope insertion to removal) was 48.8 ± 17.8 min. Procedure duration for the cases that required conversion from MAC to GET included the time the procedure was paused in order to intubate. The average anesthesia duration, defined as induction of anesthesia to end of anesthesia, was 61.8 ± 18.6 min, overall.
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Fig. 2 Number of events in procedures using MAC or GET. MAC monitored anesthesia care, GET general endotracheal anesthesia
Fig. 3 Diagnostic and therapeutic yields for procedures using MAC (n = 166) and GET (n = 12). MAC monitored anesthesia care, GET general endotracheal anesthesia
Sedation-Related Adverse Events There were a total of 32 intra-procedure SRAEs occurring in 30 (17 %) of the 178 procedures and 26 (15.8 %) of the 166 MAC procedures (Fig. 2). Intra-procedure respiratory events included hypoxia, three events (1.7 % of procedures); mask ventilation, one event (\1 %); and unplanned endotracheal intubation, three events (1.7 %). Intra-procedure cardiovascular or hemodynamic events included transient hypotension to SBP \90 requiring vasopressor use, 21 events (11.8 %), and tachy- or brady-arrhythmia requiring treatment, two events (1.1 %). There were no intra-procedure cardiac arrests or deaths. Premature procedure termination related to sedation occurred in two patients (1.1 %) under MAC anesthesia. In one patient, this was due to acute shortness of breath following the initial administration of midazolam. In the second patient, subcutaneous emphysema of the face and neck developed approximately 30 min into the procedure. This outcome was suggestive of airway injury from a difficult to place nasopharyngeal airway device verses a small, self-contained esophageal or posterior pharyngeal perforation which were seen neither on endoscope withdrawal nor on barium studies. The subcutaneous emphysema resolved with conservative management, and the patient was discharged several days later in stable condition. Three additional cases required intra-procedure conversion from MAC to GET, one due to inadequate sedation, one for airway protection in the setting of food, and the third due to difficult oxygenation. The SBE procedure was ultimately completed successfully in all three patients under GET. Interventions and Yields A total of 188 endoscopic interventions were performed in 129 of the 178 SBEs. These included tattooing of the bowel
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wall in 62 of the 178 cases (34.8 %). Biopsies were taken in 60 cases (33.7 %). Interventions to achieve hemostasis were performed in 39 cases (21.9 %). Additional endoscopic therapies included polypectomy in five cases (2.8 %), foreign body removal in five cases (2.8 %). Stricture dilation, sphincterotomy, sphincteroplasty, and biliary stenting were each performed once (\1 %). A diagnosis was made in 105 cases (diagnostic yield = 59 %), and a therapeutic intervention was performed in 54 cases (therapeutic yield = 30 %). Separate yields for MAC and GET sedation are shown in Fig. 3. A diagnosis was made in 97 of the 166 MAC cases (58.4 %) and 8 of the 12 GET cases (66.7 %). Therapeutic intervention was performed in 50 MAC cases (30.1 %) and 4 GET cases (33.3 %).
Regression Analysis Univariate logistic regression was performed to assess associations between predictor variables and SRAEs (Tables 2, 3) for all cases. Of these variables, only anesthesia duration and procedure duration were associated with adverse events (odds ratio [OR] 1.04; P \ 0.001 and OR 1.03; P = 0.003, respectively). A multivariate logistic regression model was created using SRAEs as the outcome variable (Table 4). The predictor variables with a P value of \0.1 on univariate analysis (anesthesia duration and procedure duration) were entered into the model. On multivariate analysis, anesthesia duration (OR 1.07, P = 0.005) was significantly associated with adverse events while procedure duration (P = 0.243) was no longer statistically significant. We also created separate univariate regression models for respiratory events and cardiovascular events. Here, the duration of anesthesia was strongly associated with
Dig Dis Sci Table 2 Univariate analysis of factors associated with intra-procedure sedation-related events Variable
Odds ratio
Confidence interval
P value
Age (years)
1.02
0.991–1.05
0.169
Sex (male) ASA class, I, II, III, IV
1.112 1.3
0.504–2.452 0.625–2.702
0.793 0.483
BMI (kg/m2)a
1.031
0.965–1.101
0.362
Anesthesia duration (mina)
Propofol (binary)
0.6
0.060–5.973
0.663
a
Ketamine (binary)
0.557
0.244–1.271
0.165
Midazolam (binary)
0.667
0.303–1.465
0.313
Fentanyl (binary)
Patient characteristics
Medication use
1.063
0.286–3.956
0.927
Procedure duration (min)
1.033
1.011–1.055
0.003
Anesthesia duration (min)
1.043
1.021–1.065
\0.001
BMI body mass index, ASA American Society of Anesthesiologists, SRAE sedation-related adverse event, min minutes a
Table 4 Multivariate analysis of factors associated with intra-procedure adverse events: adjusted odds ratios by logistic regression
Increase in risk of an SRAE for each additional kg/m2
Table 3 Univariate analysis of comorbid conditions associated with intra-procedure sedation-related events Comorbidity
Odds ratio
Confidence interval
P value
CHF
0.636
0.178–2.279
0.487
CAD
1.119
0.440–2.850
0.813
Hypertension
1.308
0.593–2.884
0.506
Asthma
0.672
0.187–2.414
0.542
COPD
0.722
0.232–2.245
0.573
GERD
1.145
0.508–2.580
0.744
Malignancy
1.526
0.679–3.430
0.307
CKD
1.526
0.178–2.279
0.487
Obesity (BMI C30)
0.719
0.320–1.615
0.425
CAD coronary artery disease, COPD chronic obstructive pulmonary disease, GERD gastroesophageal reflux disease, CKD chronic kidney disease, BMI body mass index
Procedure duration (mina)
Coefficient
Standard error
OR
95 % CI
P value
-0.028
0.024
0.972
0.93–1.02
0.234
0.066
0.023
1.068
1.02–1.12
0.005
OR odds ratio, CI confidence interval, min minutes Increase in risk of SRAE for each additional minute
trended toward significance (P = 0.079). For cardiovascular SRAEs, the model included age (P = 0.096 on univariate analysis) in addition to anesthesia duration and procedure duration. However, these did not remain statistically significant on multivariate analysis (P = 0.176, P = 0.229, and P = 0.786, respectively). The univariate and multivariate analyses were also conducted specifically on the 166 cases performed with MAC. In univariate analysis, procedure duration (P = 0.012) and anesthesia duration (P = 0.001) were significantly associated with the occurrence of an SRAE in MAC procedures. Only anesthesia duration remained significant (OR 1.05, P = 0.025) on multivariate analysis. When selecting for respiratory SRAEs in MAC cases, only anesthesia duration was significantly associated (P = 0.012) on univariate analysis. Selecting for cardiovascular SRAEs in MAC, both procedure duration (P = 0.001) and anesthesia duration (P = 0.007) were significant on univariate analysis. On multivariate analysis for these variables, procedure duration trended toward significance (OR 1.08, P = 0.054), while anesthesia duration was no longer significant.
Discussion respiratory SRAEs (P = 0.005) as well as for cardiovascular SRAEs (P \ 0.001). Duration of the endoscopic procedure was associated with cardiovascular events (P \ 0.001). Patient-related parameters, including increasing age, higher ASA class, and increasing BMI, as well as the listed medical comorbidities were not statistically associated with either respiratory or cardiovascular SRAEs (P [ 0.05). Multivariate analysis was again performed for predictor variables with a P value of \0.1. For respiratory SRAEs, this included anesthesia duration as well as past medical history of CAD (P = 0.061). Anesthesia time remained significant for respiratory SRAEs (P = 0.008), and CAD
This study demonstrates the safe and efficacious use of MAC sedation for SBE while also reporting the wide variety of indications and treatment options for which SBE is performed. The study also highlights that the procedure length inherently characteristic of SBE may increase the risk of adverse events. Monitored anesthesia care without endotracheal intubation is becoming increasingly common for advanced endoscopic procedures such as ERCP and EUS [18]; however, data regarding sedation for deep enteroscopy procedures such as SBE are limited. There is some information available regarding sedation in double-balloon enteroscopy (DBE), but a much greater percentage of
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patients in these studies received GET than our study [11, 19, 20]. One recent report which aimed to evaluate the safety of GET in 108 DBE cases described a relatively high frequency of hypotension (30.6 %), hypoxia (21.3 %), and apnea (17.6 %) [11]. However, as these were reversible complications treated by the anesthesiologist, their study still recommended GET for DBE as an alternative to conscious sedation [11]. Given that nurse-administered conscious sedation is inherently limited compared to MAC, it is not surprising that a GET was preferred in this study. In contrast, another report found no difference in overall complication rates in 214 DBEs, of which 40.2 % were performed under GET while the remaining patients received MAC [20]. In our study, most of the adverse events were minor; for example, 24 (13.5 % of all cases) of these events were transient hypotension or arrhythmia managed pharmacologically by the anesthesiologist without needing to interrupt the procedure. We also observed a lower rate of sedation-related adverse events (17 % of procedures) than previous reports evaluating deep enteroscopy, even though we included SBE-assisted ERCP, a technically complicated procedure, in the study group [21]. At our institution, all advanced endoscopy procedures are staffed by anesthesiologists, and they have therefore gained significant experience in these procedures. Their resulting expertise may contribute to our lower rate of SRAEs [18]. The relatively low complication rate also partially stems from the fact that we only considered adverse events (such as hypotension or arrhythmias) that were clinically significant requiring some type of pharmacologic anesthesiologist intervention, as opposed to all episodes when patients became transiently hypotensive, tachycardic, or bradycardic. Another study of anesthesia in advanced endoscopy, for example, defined hypotension or hypertension as any change in blood pressure [20 % from baseline, which resulted in 41 % of their cohort being described as having hypotension versus 11.8 % in our study [13]. This broad definition may not accurately reflect clinically significant adverse events. On the other hand, an 11.8 % rate of hypotension requiring vasopressor use is not insignificant. Decreases in systemic vascular resistance, cardiac output, and blood pressure are among the known pharmacologic effects of propofol, which was given alone or in combination with other sedatives to most patients in our study [3]. However, most periods of hypotension were brief, required only short infusions of vasopressor agents, and did not affect the overall success of the procedure. The observed frequency of hypotension is also within the range of prior studies regarding propofol-based sedation in ERCP, reported from 0.8 % up to 18.9 %, though data for SBE is limited [9, 12,
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14]. As propofol-based MAC is well established for other advanced endoscopy procedures, these findings together lead us to conclude that MAC sedation such as with propofol is safe for SBE as well and serves as a practical alternative to GET. We also sought to identify risk factors associated with sedation-related adverse events. We observed that duration of anesthesia was a strong and independent predictor for the occurrence of a sedation-related adverse event in SBE. Given that SBE is inherently a long procedure, the risk of even performing it must be considered, but can be weighed against the benefits of evaluating and possibly treating lesions deep in the small bowel otherwise outside of the reach of a standard enteroscope. Reassuringly, our study reveals that despite the duration, most patients tolerated the procedure with MAC sedation without major sedation-related complications. Further studies are required to identify patient-related risk factors and perhaps develop additional tools to predict adverse events, which may help guide choice of sedation. Regarding the efficacy of MAC in this study, very few cases required conversion from MAC to GET due to sedation. The overall diagnostic yield of SBE was 59 % and the overall therapeutic yield was 30 %. For the 166 procedures performed under MAC, the diagnostic yield was 58 % and the therapeutic yield was 30 %. These values are consistent with the findings of earlier studies [1, 22–25], implying that our use of predominately MAC sedation does not affect procedure outcomes and supports its wider use as an alternative to GET. A limitation of our study was the fact that the sedation approach was not randomized, constraining direct comparisons of MAC to GET. As GET is not routinely performed for SBE at our institution, the number of GET cases was small, which limited the conclusions that can be drawn about this sedation method. As such, patient characteristics comparing the MAC and GET groups were omitted. Additionally, this was a retrospective, single-center cohort. However, our database was created prospectively and is to our knowledge among the larger SBE cohorts published to date [1, 21–29]. Randomized controlled trials are needed to truly compare MAC to GET, but the results of this investigation support the widening role of MAC in advanced endoscopic procedures such as SBE. In summary, this work demonstrates that MAC is a safe and efficacious sedation approach for the majority of patients undergoing SBE. Conversion to GET was infrequently required in the MAC cases. Anesthesia-related complications were rare overall, and reducing the duration of anesthesia may decrease the risk of adverse events for patients undergoing SBE. Conflict of interest
None.
Dig Dis Sci
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