A new risk tool to quickly identify surgery patients at greatest risk for opioid-induced respiratory depression is being developed by Michigan and Florida researchers, according to a poster presented at PAINWeek 2015 reported by Medscape.

The tool will better equip clinicians to closely monitor at-risk patients, which should reduce adverse events, increase patient safety, and improve patient satisfaction, lead author Nicole Humbert, PharmD, Trinity Hospital (Livonia, Michigan) told Medscape.

Humbert and colleagues analyzed 13,838 patients who received an opioid within 24 hours of surgery. Of these, 114 patients received naloxone — an opioid antagonist that reverses the effects of opioids, including depression of the respiratory system — and 13,724 patients did not receive naxolone.

Researchers then observed individual and iatrogenic risk factors, according to Medscape:

  • Individual: age; airway obstruction; cardiac, hepatic, pulmonary, and renal function; and surgery type.
  • Iatrogenic: percentage of patients receiving naloxone on postoperative day zero vs postoperative days 1 and 2; the percentage of patients receiving intravenous opioids and sedatives within 12 hours of receiving naloxone; and the percentage of patients receiving long-acting opioids.

These risk factors were weighted and scored, and the higher the score, the more likely the patient would require naloxone.

Medscape reports that surgery patients could be categorized according to the presence or absence of five risk factors:

  1. Female sex
  2. Obstructive sleep apnea
  3. Renal dysfunction (glomerular filtration rate ? 29 ml/min)
  4. Hepatic dysfunction (albumin level ? 3.0 g/dl), and
  5. Upper abdominal surgical procedures.

The factor associated with the highest risk (2.22) was hepatic dysfunction. On the basis of their weighted scores, patients fell into one of four categories: ‘low,’ ‘moderate,’ ‘high,’ or ‘very high.’

The ‘low’ score category included 7400 patients (53% of the patient population), who accounted for only 0.32% of those receiving naloxone. By contrast, 229 ‘very-high’ score patients accounted for only 1.65% of the patient population but 4.37% of patients who took naloxone, Medscape reported.

According to Humbert, patients in the very-high-risk or high-risk groups would need to be monitored more carefully for OIRD, including more frequent assessment of vital signs and pulse oximetry monitoring.

Source: Medscape