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Continuous Pulse Oximetry and Capnography Monitoring for Postoperative Respiratory Depression and Adverse Events: A Systematic Review and Meta-analysis

Lam, Thach MD*; Nagappa, Mahesh MD; Wong, Jean MD*; Singh, Mandeep MD, MSc*; Wong, David MD*; Chung, Frances MBBS*

doi: 10.1213/ANE.0000000000002557
Respiration and Sleep Medicine: Systematic Review Article
Continuing Medical Education

BACKGROUND: Death and anoxic brain injury from unrecognized postoperative respiratory depression (PORD) is a serious concern for patient safety. The American Patient Safety Foundation has called for continuous electronic monitoring for all patients receiving opioids in the postoperative period. These recommendations are based largely on consensus opinion with currently limited evidence. The objective of this study is to review the current state of knowledge on the effectiveness of continuous pulse oximetry (CPOX) versus routine nursing care and the effectiveness of continuous capnography monitoring with or without pulse oximetry for detecting PORD and preventing postoperative adverse events in the surgical ward.

METHODS: We performed a systematic search of the literature databases published between 1946 and May 2017. We selected the studies that included the following: (1) adult surgical patients (>18 years old); (2) prescribed opioids during the postoperative period; (3) monitored with CPOX and/or capnography; (4) primary outcome measures were oxygen desaturation, bradypnea, hypercarbia, rescue team activation, intensive care unit (ICU) admission, or mortality; and (5) studies published in the English language. Meta-analysis was performed using Cochrane Review Manager 5.3.

RESULTS: In total, 9 studies (4 examining CPOX and 5 examining continuous capnography) were included in this systematic review. In the literature on CPOX, 1 randomized controlled trial showed no difference in ICU transfers (6.7% vs 8.5%; P = .33) or mortality (2.3% vs 2.2%). A prospective historical controlled trial demonstrated a significant reduction in ICU transfers (5.6–1.2 per 1000 patient days; P = .01) and rescue team activation (3.4–1.2 per 1000 patient days; P = .02) when CPOX was used. Overall, comparing the CPOX group versus the standard monitoring group, there was 34% risk reduction in ICU transfer (P = .06) and odds of recognizing desaturation (oxygen saturation [SpO2] <90% >1 hour) was 15 times higher (P < .00001). Pooled data from 3 capnography studies showed that continuous capnography group identified 8.6% more PORD events versus pulse oximetry monitoring group (CO2 group versus SpO2 group: 11.5% vs 2.8%; P < .00001). The odds of recognizing PORD was almost 6 times higher in the capnography versus the pulse oximetry group (odds ratio: 5.83, 95% confidence interval, 3.54–9.63; P < .00001). No studies examined the impact of continuous capnography on reducing rescue team activation, ICU transfers, or mortality.

CONCLUSIONS: The use of CPOX on the surgical ward is associated with significant improvement in the detection of oxygen desaturation versus intermittent nursing spot-checks. There is a trend toward less ICU transfers with CPOX versus standard monitoring. The evidence on whether the detection of oxygen desaturation leads to less rescue team activation and mortality is inconclusive. Capnography provides an early warning of PORD before oxygen desaturation, especially when supplemental oxygen is administered. Improved education regarding monitoring and further research with high-quality randomized controlled trials is needed.

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From the *Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada; and Department of Anesthesia & Perioperative Medicine, London Health Sciences Centre and St. Joseph Health Care, Western University, London, ON, Canada.

Accepted for publication August 16, 2017.

Funding: Supported by the Department of Anesthesiology, Toronto Western Hospital, University Health Network, University of Toronto.

Conflicts of Interest: See Disclosures at the end of the article.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website.

Reprints will not be available from the authors.

Address correspondence to Frances Chung, MBBS, Department of Anesthesiology and Pain Medicine, Toronto Western Hospital, University Health Network, University of Toronto, 399 Bathurst St, MCL 2–405, Toronto, ON M5T 2S8, Canada. Address e-mail to

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© 2017 International Anesthesia Research Society
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