Original Articles
Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy

https://doi.org/10.1067/mge.2002.124208Get rights and content

Abstract

Background: Recommendations from the American Society of Anesthesiologists suggest that monitoring for apnea using the detection of exhaled carbon dioxide (capnography) is a useful adjunct in the assessment of ventilatory status of patients undergoing sedation and analgesia. There are no data on the utility of capnography in GI endoscopy, nor is the frequency of abnormal ventilatory activity during endoscopy known. The aims of this study were to determine the following: (1) the frequency of abnormal ventilatory activity during therapeutic upper endoscopy, (2) the sensitivity of observation and pulse oximetry in the detection of apnea or disordered respiration, and (3) whether capnography provides an improvement over accepted monitoring techniques. Methods: Forty-nine patients undergoing therapeutic upper endoscopy were monitored with standard methods including pulse oximetry, automated blood pressure measurement, and visual assessment. In addition, graphic assessment of respiratory activity with sidestream capnography was performed in all patients. Endoscopy personnel were blinded to capnography data. Episodes of apnea or disordered respiration detected by capnography were documented and compared with the occurrence of hypoxemia, hypercapnea, hypotension, and the recognition of abnormal respiratory activity by endoscopy personnel. Results: Comparison of simultaneous respiratory rate measurements obtained by capnography and by auscultation with a pretracheal stethoscope verified that capnography was an excellent indicator of respiratory rate when compared with the reference standard (auscultation) (r = 0.967, p < 0.001). Fifty-four episodes of apnea or disordered respiration occurred in 28 patients (mean duration 70.8 seconds). Only 50% of apnea or disordered respiration episodes were eventually detected by pulse oximetry. None were detected by visual assessment (p < 0.0010). Conclusions: Apnea/disordered respiration occurs commonly during therapeutic upper endoscopy and frequently precedes the development of hypoxemia. Potentially important abnormalities in respiratory activity are undetected with pulse oximetry and visual assessment. (Gastrointest Endosc 2002;55:826-31.)

Section snippets

Patient selection

Patients undergoing elective complex upper endoscopic procedures, defined as ERCP, upper endoscopy with expandable metal stent placement, photodynamic therapy, EUS, and therapeutic push enteroscopy were considered candidates for inclusion. These procedures were chosen because they commonly are prolonged (>30 minutes) and frequently require administration of multiple doses of agents traditionally used for sedation and analgesia. Exclusion criteria were as follows: age less than 18 years,

Results

Forty-nine patients (28 men, 21 women; mean age 57.1 years, range 28-88 years) participated in the study (Table 1); 57% were ASA class I or II.Comorbid illnesses included liver disease (22.4%), chronic obstructive pulmonary disease (16%), ischemic heart disease (14.3%), and renal insufficiency (2%). Tobacco or ethanol were currently being used by, respectively, 51% and 6% of the patients. Medication use included narcotics (33%), benzodiazepines (12%), and other sedatives or psychotropic agents

Discussion

The current study is the first prospective evaluation of the utility of capnography in providing a real time, breath to breath, graphic assessment of respiratory activity during therapeutic upper endoscopy. The extended monitoring provided by capnography resulted in an accurate assessment of respiratory rate when compared to auscultation with a pretracheal stethoscope as the reference standard. Apnea and disordered respiration occurred in over 50% of patients and frequently preceded the

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Reprint requests: John J. Vargo, MD, Department of Gastroenterology, Desk A-30, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195.

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