Digestive Diseases and Sciences

, Volume 57, Issue 7, pp 1899–1907

Prospective Description of Coughing, Hemodynamic Changes, and Oxygen Desaturation During Endoscopic Sedation


  • Abdul Hamid El Chafic
    • Division of Gastroenterology, Department of MedicineIndiana University School of Medicine
  • George Eckert
    • Division of Gastroenterology, Department of MedicineIndiana University School of Medicine
    • Division of Gastroenterology, Department of MedicineIndiana University School of Medicine
Original Article

DOI: 10.1007/s10620-012-2057-z

Cite this article as:
El Chafic, A.H., Eckert, G. & Rex, D.K. Dig Dis Sci (2012) 57: 1899. doi:10.1007/s10620-012-2057-z



Deep sedation is increasingly used for endoscopy. The impact of sedation level on hemodynamic status, oxygenation, and aspiration risk is incompletely described.


To describe the incidence of intraprocedural cough, hemodynamic changes, oxygen desaturation, and their relationship to clinical factors and sedation level.


Detailed prospective recordings of hemodynamic changes, oxygen desaturation, and cough during 757 nonemergent endoscopic procedures done under sedation using propofol, midazolam, and/or fentanyl.


Thirteen percent of patients had at least one cough and 3% had prolonged cough. Cough was more common in nonsmokers (P = 0.05), upper endoscopy (P < 0.0001), with propofol (P = 0.0008), longer procedures (P = 0.0001), and hiccups (P = 0.01). The association between supine positioning during colonoscopy and cough approached significance (P = 0.06). Oxygen desaturation was rare (4%) and associated only with deep sedation (P = 0.02). Mean systolic and diastolic blood pressure (BP) dropped by 7.3 and 5.6% respectively. Decreases in systolic BP were more common in whites (P = 0.03), males (P = 0.004), nonsmokers (P = 0.04), during colonoscopy (P < 0.0001), and in patients receiving midazolam and fentanyl (P = 0.01). Heart rate (HR) dropped >20% from baseline in 15% of patients and was more common during colonoscopy (P = 0.002). HR increased >20% in 20% of patients and was more common with coughing (P < 0.0001) and in younger patients (P = 0.0002). No patient required pharmacologic treatment of BP or HR.


We have described procedural predictors of cough that may help clinicians reduce the risk of aspiration during endoscopy. Hemodynamic changes during endoscopy are common but largely clinically insignificant.


Endoscopy, digestive system/adverse effectsDeep sedation/adverse effectsPropofol/adverse effectsHemodynamicsCoughOxygen saturation


Sedation has been found to be a major contributor to complications occurring during endoscopic procedures [16]. However, what constitutes a clinically significant complication of sedation is arguable. For example, sedation-induced death, neurologic sequelae, and aspiration pneumonia are clear-cut complications. On the other hand, development of hypotension or bradycardia, even if they require pharmacologic treatment but are readily reversible without sequelae, could be considered clinically insignificant complications that are an expected part of routine endoscopic sedation. Similarly, microaspiration could be considered clinically insignificant if it results in coughing but not in pulmonary infection or induction of prolonged bronchospasm. The experienced endoscopist recognizes that the occurrence of changes such as hypotension, severe heart rate changes, coughing, and oxygen desaturation, while not in themselves necessarily complications, must be recognized and in some cases treated because, if allowed to persist, clinically important complications may develop.

In our unit, we began using propofol administered by trained registered nurses more than a decade ago. During this interval, we commonly induced deep sedation and even general anesthesia during routine endoscopic procedures, without the occurrence of death or permanent sequellae [714]. Anecdotally, however, we frequently saw substantial hemodynamic changes which seemed almost entirely to lack clinical significance. We also anecdotally observed that occasional patients developed prolonged coughing, postprocedural bronchospasm, unexplained fever, and evidence of pulmonary infection requiring treatment with antibiotics. Such anecdotal cases led us to an approach of meticulous airway protection, including avoidance of deep sedation in patients with acute gastrointestinal bleeding, achalasia, and known delayed gastric emptying [12, 13], a policy of vigorous suctioning of the hypopharynx prior to esophageal intubation during upper endoscopy, complete suctioning of the esophagus and stomach prior to examination of the upper GI tract, and careful attention to position change during colonoscopy and to maintaining the availability of oral suctioning to manage reflux during colonoscopy [15]. A study from Italy recently described that 18 of 17,542 patients sedated by Monitored Anesthesia Care during endoscopy required antibiotic treatment for aspiration (0.1%), and that aspiration was a significant contributor to episodes of desaturation [16]. Thus, the occurrence of aspiration is more frequent than perforation in most endoscopic practices, and factors associated with aspiration risk should be of interest to endoscopists. It is reasonable to speculate that the increased use of deep sedation with propofol endoscopy could result in a clinically significant increase in pulmonary infections associated with aspiration. In our experience, most patients who develop pulmonary infection after endoscopy had evident coughing and often had evidence of reflux of gastric contents during the procedure.

We found no reports in the medical literature that describe the incidence of coughing during endoscopy, or factors associated with coughing. Such a study could be valuable to understanding mechanisms of aspiration during endoscopy and preventing aspiration, especially if some or most episodes of postprocedural pulmonary infection are associated with significant coughing. Therefore, we undertook a prospective documentation of the occurrence of intraprocedural cough, hemodynamic changes, and oxygen desaturation, and the relationship of these events to procedural factors and sedation level. Several previous studies have included the results of prospective measurements of hemodynamic changes throughout the course of endoscopic procedures [2, 3, 6, 9, 1113, 1741]. However, few studies have had the sole focus of a detailed description of the quantitative changes in hemodynamic parameters during endoscopy and their relationship to specific agents, sedation level, and clinical factors.


Study Population

We prospectively recorded sedation-related events in 757 patients. The study was conducted as a quality improvement project to identify measures that could reduce our incidence of postprocedural pulmonary infections. The events were recorded by college students working in the endoscopy unit on quality-related projects in the summer of 2009. Permission to review the data for purposes of publication was granted by the Institutional Review Board at Clarian Health Partners. The students were trained to make the recordings by the senior investigator (D.R.). Sample size reflected the number of studies they could complete during their summer vacation. Consecutive patients were included to the extent that a student was available to make measurements, i.e. a patient could not be included if the students were already recording data on another patient or not otherwise available.

Patient Monitoring and Data Collection

Clinical factors recorded for each patient included age, gender, race, whether the patient was an active smoker, had a history of asthma, what medications they received for their endoscopic procedure, the type of procedure, the duration of procedure, and what treatments were performed during the procedure. Smoking and asthma were recorded as smoking alone, asthma alone, both or neither (Table 1).
Table 1

Patient demographics (n = 757)



Age, years, mean (SD)

57.5 (14.4)

Gender n (%)


354 (47%)


403 (53%)

Patient location n (%)


57 (8%)


700 (92%)

Race n (%)


673 (89%)

 African American

71 (9%)


5 (1%)


1 (0%)


6 (1%)

 Middle Eastern

1 (0%)

Respiratory risks n (%)


181 (24%)


59 (8%)


37 (5%)


480 (63%)

SD standard deviation, COPD chronic obstructive pulmonary disease

During the procedure, blood pressure was recorded every 5 min beginning with the onset of the initial sedative medication, or more often if indicated by changes in clinical status. Heart rate was recorded every 2 min (for monitoring purposes, the heart rate was measured continuously as was the electrocardiogram). Oxygen saturation was measured continuously and recorded for the study purposes every 1 min, and sedation level was recorded every 2 min using the Modified Observer’s Assessment of Alertness/Sedation Scale (MOAAS) scale. [The MOAAS score ranges from 0 to 6 (0 = unresponsive to deep stimuli, 1 = unresponsive to shaking, 2 = responsive to shaking only, 3 = responsive to loud verbal command, 4 = lethargic response to normal verbal command, 5 = responsive and alert, and 6 = agitated) [42]. Deep sedation was defined as a MOAAS score ≤ 1 [43].] Every instance of cough and hiccup was recorded by the study assistant. The study assistant also made note of any interventions involving sedation-related issues, such as the use of atropine for bradycardia, pharmacologic treatments of blood pressure, placement of oral or nasal airways, and use of positive pressure ventilation (bag-mask ventilation). All patients were given supplemental oxygen by nasal cannula at a rate of 4 l per minute.

Sedation Used

All the patients were sedated by trained registered nurses under the supervision of the endoscopist. No anesthesiologist or anesthetist was involved in any case. No patient received topical or pharyngeal anesthesia. Some patients received intravenous lidocaine in an attempt to prevent pain from injection of propofol. Our sedation protocols using propofol as well as opioids and benzodiazepines are based on titration of selected agents to desired levels of sedation and have been described previously [9, 1113]. Agents were selected for each patient based on the clinical judgment of the endoscopist and the sedation nurse. Patients were more likely to receive opioids and benzodiazepines or combinations of opioids, benzodiazepines, and propofol (as opposed to propofol alone) if they had sleep apnea or higher risk airway assessments. All patients undergoing upper endoscopy received at least small doses of opioids and/or benzodiazepine.

Statistical Methods

Two sets of statistical analyses were performed. The first examined associations of changes in blood pressure, heart rate, cough, and oxygen saturation with other factors at the level of the entire procedure and the second analysis used the measurements collected longitudinally throughout the procedure. For the procedure-level analyses, each of the predictors of systolic blood pressure (SBP) and diastolic blood pressure (DBP) percent change from baseline during the procedure were tested for significance individually using correlation coefficients or ANOVA for continuous categorical predictors, respectively. Multivariable analyses were performed by including all possible predictors simultaneously in an analysis of covariance model. Analyses of the SBP and DBP data collected throughout the procedure were performed using mixed-model ANOVA with a random effect to account for the within-patient correlation. Similarly, predictors of the occurrence of any cough during the procedure, oxygen saturation <90% during the procedure, heart rate percent change from baseline >20%, were examined using ANOVA and χ2 tests for continuous and categorical predictors, respectively. The multivariable models for these outcomes were fit using logistic regression. The longitudinal analyses of the measurements throughout the procedure were analyzed using generalized estimating equation (GEE) methodology applied to logistic regression models account for the within patient correlation.


Patients and Procedures

A clinical description of the 757 patients evaluated is given in Table 1. The number of inpatients was small, and there were no differences between inpatients and outpatients in type of sedation used or any measured parameter (data not shown).

Table 2 describes the procedures performed, including interventions, the sedative agents used, the deepest level of sedation achieved, and whether abdominal pressure or position change was used during procedures. The majority of the patients were outpatients and none of the patients was undergoing an emergent procedure. The “other” category under procedures includes primarily push enteroscopy and deep small bowel enteroscopy. As can be seen from Table 2, the majority of patients reached deep sedation (MOAAS score ≤1) or general anesthesia at some point during the procedure. Table 2 also shows that abdominal pressure was more often used than position change to assist in colonoscopy. The majority of patients (74%) had either biopsy or some therapeutic intervention performed during the procedure. Although most patients reached general anesthesia at some point during the procedure (Table 2), when sedation levels at all times for all patients were considered, the median level of sedation on the MOAAS score was 1 and the mean was 1.7 (SD 1.7).
Table 2

Procedures, sedation agents, sedation levels, and ancillary maneuvers

Procedure type n (%)


338 (45%)


254 (34%)


80 (11%)


65 (9%)


20 (1%)

Procedure duration, min (SD)

23.0 (14.4)

Intervention n (%)


221 (29%)


197 (26%)


30 (4%)


21 (3%)


11 (1%)


195 (26%)


75 (11%)

Sedation drugs n (%)

 P + M + F

476 (63%)

 M + F

197 (26%)


66 (9%)

 P + M

10 (1%)

 P + F

5 (1%)


2 (0%)


1 (0%)

Intravenous lidocaine used n (%)


263 (35%)


494 (65%)

Maximum sedation level n (%)


577 (76%)


16 (2%)


39 (5%)


51 (7%)


45 (6%)


26 (3%)


2 (0%)

Abdominal pressure during procedure n (%)


121 (16%)


636 (84%)

Any position change n (%)


18 (2%)


739 (98%)

P propofol, M midazolam, F fentanyl, EGD esophagogastroduodenoscopy, EGC EGD and colonoscopy, EUS endoscopic ultrasonography, APC argon plasma coagulation, SD standard deviation

aSedation levels according to MOAAS scale


Twenty-four percent of patients were smokers with or without chronic obstructive pulmonary disease, 8% had asthma, 5% reported both smoking and asthma, and the rest had no known chronic or acute, upper or lower pulmonary disease (Table 1). Thirteen percent of patients had at least one cough during the procedure. Two percent of patients coughed only once, another 2% coughed twice, 3% coughed three times, 2% coughed four times, 1% coughed 5 times, and 3% developed a prolonged cough (>5 times). Smokers had a lower risk of cough than patients who did not smoke and did not have asthma (Table 3), and cough occurred less often when patients underwent colonoscopy alone. Patients sedated with propofol with or without other agents had a higher risk of cough than patients who received midazolam and/or fentanyl without propofol. Patients who were observed to have at least one hiccup during the procedure were at higher risk for cough. Longer procedures were associated with an increased risk for cough. Thirty-three percent of those subjected to position change developed cough compared to 12% of those with no position change; however, the difference was of borderline significance in multivariable analysis (OR = 3.93, P = 0.06), and was not evident in the longitudinal analysis. There was no association between the use of intravenous lidocaine and the incidence of cough (OR = 0.77, P = 0.321).
Table 3

Significant associations of coughing in multivariate analysis

Clinical predictors

Any cough during procedure (procedural level analysis)

Any cough during procedure (longitudinal level analysis)


95% CI



95% CI

P value

Smoking/non smoking or asthmatic







Colonoscopy/other procedures







Position change; yes/no







P/(M + F)







(P + M + F)/(M + F)







Any hiccup during procedure; yes/no







Procedure durationa




OR odds ratio, CI confidence interval, NS not significant, P propofol, M midazolam, F fentanyl

aOdds ratio calculated for 15-min difference; analysis cannot be done for procedure duration in the longitudinal level model

Oxygen Saturation

The average oxygen saturation during procedures was 97.9% (SD 2.5%). The average change from baseline in oxygen saturation during procedures was only 0.3% (Table 4). Ninety-five percent of patients dropped their saturation at some point in the procedure more than 4%, but only 4% dropped their saturation below 90%, and only 2% were below 85%. Using a definition of oxygen saturation as <90%, fitting a multivariable model to the small number of desaturations was questionable. In bi-variate analyses, females were at lower risk for desaturation (P = 0.04) and risk for desaturation increased with sedation level. In the multivariable model, only deeper sedation level remained significant (OR = 1.44, P = 0.02). No patient required placement of an airway or bag-mask ventilation.
Table 4

Alteration in vital signs and minor complications during the procedure

Average Δ vital signs from baseline

Mean (SD)


N (%)


−11.1 (23.1)

SBP < 90

181 (23.9%)


−7.3 (17.8)

O2 saturation < 90

31 (4.0%)


−6.1 (16.7)

O2 saturation < 85

13 (1.7%)


−5.6 (25.4)

O2 saturation drop > 4%

718 (94.8%)


−1.1 (11.0)

HR > 100

60 (7.9%)

% Δ HR

−0.3 (14.8)

HR < 60

219 (28.9%)

Δ O2 sat

0.3 (2.8)

Any cough

95 (12.5%)

% Δ O2

0.3 (2.8)

Any hiccup

52 (6.9%)

Δ = change

SBP systolic blood pressure in mm Hg, DBP diastolic blood pressure in mm Hg, HR heart rate in beats per minute, O2 sat oxygen saturation (%)

Changes in Blood Pressure

Mean systolic blood pressure (SBP) dropped significantly during procedures by an average of 7.3% (SD 17.8), and diastolic blood pressure (DBP) by 5.6% (SD 25.4) (Table 4). The maximum drop in SBP was <10% in 28% of patients, 10–19% in 26% of patients, 20–29% in 25% of patients, 30–39% in 14% of patients, 40–49% in 6% of patients, and >50% in 1% of patients. These changes resolved spontaneously in all cases and none of the patients required pharmacologic treatment or cessation of the procedure. There was no correlation between procedure duration and blood pressure variation during the procedure, and borderline association of diastolic blood pressure drop with deeper sedation level in the longitudinal analysis model.

Table 5 shows factors that reached statistical significance in their association with reductions in SBP during endoscopic procedures in the multivariable analysis. Thus, males had a 3.6% greater decrease in SBP than females, whites had a greater decrease than other races combined, those who were neither smokers nor asthmatics had a greater decrease than smokers and asthmatics, patients undergoing colonoscopy had a greater decrease than those undergoing all other procedures combined irrespective of type and dosage of sedative agents used, and patients receiving fentanyl and midazolam had a greater decrease than those receiving propofol alone. Each of these factors were significant when compared at either a procedural level or in the longitudinal analysis (Table 5). Table 6 shows the corresponding factors that reached significance for DBP for either the procedural level or longitudinal analyses.
Table 5

Significant clinical predictors of SBP decrease in multivariate analysis using two methods

Clinical predictors

% Decrease in SBP (procedural level analysis)

% Decrease in SBP (longitudinal level analysis)



P value



P value








Whites/other races







Neither smokers nor asthmatics/smokers







Colonoscopy/other procedures







(M + F)/P







SBP systolic blood pressure, P propofol, M midazolam, F fentanyl, SE standard error

Table 6

Significant clinical predictors of DBP decrease in multivariate analysis using two methods

Clinical predictors

% Decrease in DBP (procedural level analysis)

% Decrease in DBP (longitudinal level analysis)



P value



P value

Whites/other races







Colonoscopy/other procedures







(P + M + F)/(M + F)







Position change during colonoscopy; no/yes







Deeper sedation level







DBP diastolic blood pressure, P propofol, M midazolam, F fentanyl, SE standard error, NS not significant

Changes in Heart Rate

There were 117 (15%) patients whose heart rate decreased more than 20% from baseline at some time during the procedure and 151 (20%) whose heart rate increased more than 20% during the procedure. No patient required pharmacologic intervention for heart rate changes. Tables 7 and 8 show factors that were associated with a ≥20% change in heart rate from baseline, in either the procedural level analysis or the longitudinal analysis. Patients undergoing colonoscopy were more likely to have a 20% or more decrease in heart rate (Table 7), and less likely to have an increase in heart rate from baseline (Table 8). Longer procedure duration was associated with both increases and decreases in heart rate (Tables 7 and 8). Younger age and coughing during the procedure were both associated with increases in heart rate.
Table 7

Significant clinical associations of heart rate drop >20% from baseline in multivariate analysis using two methods

Clinical predictors

HR drop > 20% during procedure (procedural level analysis)

HR drop > 20% during procedure (longitudinal level analysis)


95% CI

P value


95% CI

P value

Smoking/neither smoking nor asthmatic







Colonoscopy/other procedures







Cough/no cough







Procedure durationa




HR heart rate, OR odds ratio, CI confidence interval, NS not significant

aOdds ratio calculated for 15-min difference; analysis cannot be done for procedure duration in the longitudinal level model

Table 8

Significant clinical predictors of heart rate rise >20% from baseline in multivariate analysis using two methods

Clinical predictors

HR rise > 20% during procedure (procedural level analysis)

HR rise > 20% during procedure (longitudinal level analysis)


95% CI

P value


95% CI

P value

Colonoscopy/other procedures







Cough/no cough







Procedure durationa











HR heart rate, OR odds ratio, CI confidence interval

aOdds ratio calculated for 15-min difference; analysis can’t be done for procedure duration in the longitudinal level model

bOdds ratio calculated for 10-year difference


In this report, we describe clinical factors associated with the development of cough during endoscopic procedures as well as changes in blood pressure, heart rate, and oxygen saturation. Although others have described hemodynamic changes during endoscopic sedation [2, 3, 6, 9, 1113, 1741], our study is among the most detailed prospective assessment of hemodynamic changes in relation to sedation levels and clinical factors thus far reported. Furthermore, to our knowledge, this is the first report of the frequency of cough during endoscopic sedation.

Although we hypothesize that development of cough might be a surrogate marker for an increased risk of aspiration-related postprocedural infection, we acknowledge that such a relationship has not been established. However, we believe it is reasonable to presume that most episodes of postprocedural pulmonary infection would be associated with intraprocedural coughing or coughing during the period of sedation. We did observe that coughing was associated with factors that might be expected to increase the risk of microaspiration, including upper endoscopy, use of propofol as a single agent, and longer procedures. Coughing was also associated with hiccuping which may occur during endoscopy during periods of gastroesophageal reflux or diaphragmatic pressure from the endoscope. In our experience, hiccuping is often associated with regurgitation of gastric contents and the onset of coughing, and we have seen several instances of apparent hiccup-induced aspiration during colonoscopy.

Our results suggest that clinicians utilizing deep sedation and general anesthesia, particularly with propofol, in nonintubated patients for endoscopic procedures, should have constant vigilance for aspiration, particularly with deeper levels of sedation, longer procedures, during hiccupping, and when colonoscopy patients are rotated to the supine position. The presence of regurgitated fluid in the mouth plus coughing suggests that microaspiration is possible or may have already occurred. Conversely, smokers had significantly less coughing than nonsmokers suggesting blunting of their cough reflex [44]. Thus, heightened vigilance to protect against microaspiration may be warranted in smokers. We acknowledge that coughing during upper endoscopy is likely related primarily to laryngeal stimulation from the upper endoscope and pharyngeal secretions. A separate study to evaluate factors associated with coughing only during colonoscopy would be informative.

There were few patients in the study who developed oxygen saturations <90%, limiting our ability to identify clinical predictors of oxygen desaturation. Multivariable analysis only identified greater depth of sedation as a risk factor for oxygen desaturation. Although most of the patients in the study reached deep sedation or general anesthesia at some point during the procedure, all episodes of desaturation were managed successfully by the sedating nurse and endoscopist, consistent with evidence that patients can be safely targeted to deep sedation by nonanesthesiologists [8]. In fact, we are aware of no scientific evidence to support the American Society of Anesthesiologist’s contention [45] or the rules of the Center for Medicare and Medicaid Services [46] that deep sedation should only be administered by anesthesia specialists.

With regard to blood pressure changes, the principal observation of our study was that variable degrees of hypotension occurred, which in some instances were >40% from baseline. Despite this, patients tolerated these changes without development of arrhythmia or cardiac complications, and the changes did not require pharmacologic treatment or cessation of procedures. These changes suggest that blood pressure alterations during endoscopic sedation are overwhelmingly clinically insignificant. However, the number of patients with blood pressure drops >40% was only 7%, and no patient had sustained drops. Certainly, a larger study might have identified patients with sustained hypotension for which pharmacologic treatment would be needed.

Blood pressure changes were greater in whites than nonwhites for uncertain reasons. Blood pressure drops were greater during colonoscopy, probably because of relative dehydration prior to the initiation of sedation. Since colonoscopy was associated with both hypotension and bradycardia, vagal responses likely also contributed to hypotension during colonoscopy. Blood pressure drops were less pronounced with propofol than with opioids and benzodiazepines, supporting the safety of propofol with regard to hemodynamic changes during endoscopy. We advocate that patients with significant decreases in blood pressure be placed temporarily in Trendelenburg and have an increase in their intravenous fluid infusion rate, but, in our study, pharmacologic treatment was never used.

Our study identified several clinical factors associated with changes in heart rate of more than 20% from baseline. Specifically, colonoscopy was associated with a greater risk of bradycardia, and coughing and upper endoscopic procedures with a greater risk of tachycardia, and longer duration of procedures was associated with both tachycardia and bradycardia. Although no patient in this study was given pharmacologic treatment for heart rate changes, we certainly treat significant degrees of bradycardia during colonoscopy with atropine or glycopyrrholate, and our clinical experience suggests that these changes are sometimes related to scope passage and vagal reactions to loop formation, rather than to the sedation itself. The observation that tachycardia is more common during cough and upper endoscopic procedures may reflect that some patients were not sufficiently sedated to initiate their upper endoscopy, precipitating a stress-induced sinus tachycardia.

Our study has limitations. Since it was not randomized, we cannot exclude the possibility that patient factors affected the choice of sedation agents, and that these patient factors underlie to some degree observed differences in cough and hemodynamic changes associated with sedation agents. Also, we again acknowledge that cough is only a surrogate for aspiration risk, and that much of the coughing that occurs during endoscopy is clinically insignificant.

In conclusion, we performed a detailed prospective analysis of the incidence of cough, hemodynamic changes, and oxygen desaturation in patients receiving a variety of sedation regimens for endoscopy and correlated the occurrence of these events with clinical factors, procedure type and duration, and sedation agents. We identified clinical predictors of cough during endoscopy, which may suggest situations for which increased vigilance is required to prevent microaspiration and potentially prevent postprocedural pulmonary infectious complications. These situations include deeper levels of sedation, propofol use, longer procedures, patients who are hiccupping, and patients who are rotated to the supine position during colonoscopy. Given the recent demonstration that postprocedural pulmonary infection is a significant problem for endoscopy [16], data of this type may be useful in developing effective measures for preventing procedure-related aspiration.

Conflict of interest


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© Springer Science+Business Media, LLC 2012