KNOW SOONER Studies have shown that monitoring of end-tidal CO₂ provides an earlier indication of respiratory distress than intermittent checks or pulse oximetry.

At certain dosages, the opioids you give to patients to manage surgical pain can lead to respiratory depression — and overdoses can lead to respiratory failure.

Intermittent spot checks of oxygenation (pulse oximetry) and ventilation (nursing assessment) are not adequate for reliably recognizing drug-induced respiratory depression in the post-operative period. Rather, you should consider continuous electronic monitoring with both pulse oximetry for oxygenation and capnography for the adequacy of ventilation for patients undergoing moderate and conscious sedation, as well as for those managing pain using a patient-controlled analgesia (PCA) pump.

Pulse oximetry. Pulse oximetry is a lagging indicator of respiratory distress — the lagging can be elongated if supplemental oxygen is being administered to the patient. While continuous monitoring with pulse oximetry is encouraged, the sole use of the technology to monitor for respiratory depression during conscious sedation is not sufficient. "Pulse oximetry is only designed to detect oxygen saturation and heart rate, not the ventilatory status of a patient," says Richard Kenney, MSM, RRT, NPS, ACCS, RCP, the director of respiratory care services at White Memorial Medical Center in Los Angeles, Calif. "By the time oxygen saturation has dropped and the alarms are alarming, you've gotten beyond that threshold of the patient having a quick recovery from that."

Nursing assessment. For patients receiving opioids, intermittent "spot checks" to determine key physiologic metrics are not sufficient in isolation. Respiration can rapidly decelerate under the influence of opioids, sometimes in a matter of minutes. By the time a patient experiencing opioid-induced respiratory depression is visited again, it can be too late to intervene.

In addition to pulse oximetry, you should also monitor with capnography for adequacy of ventilation. Studies have shown that monitoring of end-tidal CO₂ (EtCO₂) provides an earlier indication of respiratory distress than pulse oximetry or intermittent checks — in one study (osmag.net/FSx7Sk), at an average of 3.7 minutes earlier than pulse oximetry.

Patients react to medication differently — a fact that is an undefined factor, for example, in the opioid naive until it is too late. The situation can be further complicated by existing conditions and treatments. Patients receiving opioids should undergo a pre-screening process to identify crucial risk factors, such as obesity and obstructive sleep apnea (OSA), as well as any potential conflicting existing prescriptions, such as benzodiazepines. The STOP-Bang questionnaire is a simple yet highly sensitive tool to screen for OSA (see "How to Identify Sleep Apnea Risk Factors").

Only part of the solution
While continuous electronic monitoring can provide an earlier indication of respiratory depression, it is only one part of the solution. Monitors are not meant to remove clinicians from the equation; instead, monitoring technology should be a multiplying factor for hands-on, proactive care. OSM