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04 Mar 2019

New Study Demonstrates the Threat of Respiratory Depression

By John Zaleski, Ph.D., CAP, CPHIMS

PRODIGY Study on Opioid-induced Respiratory Depression

A new study published in the Journal of Critical Care found that occurrences of opioid-induced respiratory depression (OIRD) on general care floors may be more common than previously documented.1 The PRODIGY study, which included 1,500 patients across 16 sites in the U.S., Europe and Asia, confirmed that OIRD occurred in 46 percent of patients.

The study’s findings are both interesting and validating. The ability to metabolize narcotics such as pain medication can vary from patient-to-patient. The use of opioids, such as hydromorphone and morphine sulfate, for example, are known to increase the risk of respiratory depression in patients who have been diagnosed with or are at risk for obstructive sleep apnea (OSA).

Identifying which patients are prime to experience decompensation is difficult, but critical to comprehensive patient safety. Many patients who experience adverse events, such as OIRD, do not follow any simple criteria for determining whether they will be at risk for obstructive or central sleep apnea.

Respiratory failure that requires emergency mechanical ventilation occurs in 44,000 patients per year in the United States.2 The cost to U.S. hospitals for OIRD interventions is estimated at nearly $2 billion per year.3 OIRD is the leading cause of in-hospital cardiopulmonary arrest (IHCA), with a rate nearly three times as high of a patient who does not receive opioids or medication with sedative properties.

More than 70 percent of patients who experience IHCA suffer an anoxic brain injury or death. In a 2014 study, Slight et al. noted, “More than 10,000 of these patients suffered an IHCA on the general care floor, which is where patients with relatively stable conditions are placed. We were surprised by the size of the increased odds of IHCA for a patient receiving opioids.”4

Learn More About Respiratory Depression Safety Surveillance

Virtua Studies On Continuous Patient Monitoring

In 2017, I was part of a team that published a smaller but similar study5 to PRODIGY on continuous patient monitoring of post-surgical patients determined to be at risk for OIRD. Our paper consisted of two separate studies on the use of continuous capnography monitoring at a medical-surgical unit at Virtua Health System in New Jersey.

The successive investigative studies were conducted to identify the utility and practical implementation of remotely communicated sustained and combinatorial capnography alarm signals in order to improve patient surveillance, and also reduce spurious or non-emergent events that are not indicative of a threat to patient safety.

By introducing sustained delays and combining multiple physiologic measurements together prior to issuing an alert, patients at risk for respiratory depression could be identified without inadvertently overlooking patients truly requiring clinical intervention. Using this approach, we were able to achieve significant reductions in total alarms (in some cases, greater than 10:1) while at the same time causing no increased risk to the patients. The results suggest that combinatorial alarm signals based on multi-parameter assessment reduced overall load better than individual-parameter sustained alarm signals.

Learn More About Clinical Alarm Surveillance

Continuous Clinical Surveillance & Patient Monitoring

The PRODIGY study focused on identifying early indicators of risk. Again, this validates our earlier findings related to monitoring for ventilation, including expired carbon dioxide, respiration rate, pulse oximetry, and other interrelated measures that define the state of the patient and provide a prognostic guide as to a patient’s ability to metabolize opioids and maintain both airway patency and adequate ventilatory effort.

The continued widespread use of PCA and the increasingly complex chronic conditions and co-morbidities presented in patients receiving postoperative pain medication raises considerable safety risks for hospitals and health systems.

Findings in such studies as Virtua and PRODIGY related to and supportive of the need for clinical surveillance add further validation and impetus to focusing on proactive notification of patient decompensation using real-time data acquired at the bedside. This approach differs greatly from the traditional retrospective approaches in which alarm signals annunciate to indicate that a patient is in trouble.

Multi-parameter physiologic monitors are critical to continuous patient monitoring and data capture. Capnography, along with continuous pulse oximetry monitoring, can provide a sensitive and early indicator of OIRD.

Smart alert signals, which include trending, consecutive alarms, sustained and combinatorial alarms, can be implemented using device-agnostic middleware for interfacing with bedside devices. Data collection and analysis would be further enhanced when methods for disseminating, exploiting and distributing both the data and the smart alarm signals are included. These latter features facilitate better patient care management and clinical workflow by tracking patients throughout the hospital, enabling dynamically adding and removing medical devices, and distributing real-time patient monitoring to dashboards and mobile devices.

Continuous clinical surveillance can be deployed to mitigate serious deterioration in patients at risk of respiratory compromise and other medical conditions in both high acuity and general care settings. Patients in intensive care units are already continuously monitored. Hence, the safe alternative is to monitor everyone continuously, even on the general care floor.

Khanna AK, Overdyk FJ, Greening C, Stefano PD, Buhre WF. Respiratory depression in low acuity hospital settings–Seeking answers from the PRODIGY trial. Journal of Critical Care. October 2018.
Respiratory Compromise as a New Paradigm for the Care of Vulnerable Hospitalized Patients Timothy A Morris MD, Peter C Gay MD, Neil R MacIntyre MD FAARC, Dean R Hess PhD RRT FAARC, Sandra K Hanneman PhD RN, James P Lamberti MD, Dennis E Doherty MD, Lydia Chang MD, and Maureen A Seckel APRN RESPIRATORY CARE • APRIL 2017 VOL 62 NO 4
AAMI Foundation. Opioid Safety & Patient Monitoring Conference Compendium. November 14, 2014. Available at:
Slight SP, Franz C, Olugbile M, Brown HV, Bates DW, Zimlichman E. Crit Care Med. 2014 ;42.
Supe D, Baron L, Decker T, Parker K, Venella J, Williams S, Beaton K, Zaleski J. A pilot study in middleware-filtered capnography alarms of continuously monitored obstructive sleep apnea patient in a medical-surgical unit. BI&T. May/June 2017.