Opioid-induced ventilatory impairment in palliative care

Opioid-induced ventilatory impairment (OIVI) is associated with 3 interlinked mechanisms:

• sedation (usually the first symptom)—depression of consciousness
• central respiratory depression—depression of respiratory drive leading to reduced respiratory rate or depth of breathing
• upper airway obstruction—depression of muscle tone (may manifest as snoring).

For indicators of opioid-induced ventilatory impairment, see the Pain and Analgesia guidelines.

In the last days of life, do not use sedation scores, consciousness level or respiratory rate to monitor for opioid-induced ventilatory impairment. These features are not reliable indicators of opioid-induced ventilatory impairment because they may be related to normal physiological changes that occur as death approaches. If opioid-induced ventilatory impairment is suspected in the last days of life, seek specialist advice.

Seek specialist advice if possible for management of opioid-induced ventilatory impairment in patients who are not in the last days of life. Management of opioid-induced ventilatory impairment depends on the causative opioid, the severity of ventilatory impairment, and the patient’s prognosis, preferences and goals of care. Management strategies include:

• reducing subsequent opioid doses
• withholding or stopping the opioid
• administering naloxone.

For patients who are slightly sedated, but remain easy to rouse, monitor closely and reduce subsequent opioid doses.

For patients who are difficult to rouse or hypoventilating, stop the opioid and consider administering naloxone in a dose appropriate to the situation. Patients with palliative care needs may be at an increased risk of an acute pain crisis or opioid withdrawal when naloxone is used; carefully consider the potential benefits and harms, and seek specialist palliative care advice if possible.

If naloxone is used, intravenous administration is preferred because it has a fast onset of action (approximately 1 minute), allowing rapid assessment of response, titration to effect, and prompt initiation of intravenous infusion if required. Rapid, complete opioid reversal using large doses of naloxone can cause return of severe pain, withdrawal in opioid-tolerant patients, and serious adverse effects (eg pulmonary oedema, cardiac arrhythmias). Small, incremental intravenous doses of naloxone are preferred unless the situation is urgent (eg medication administration error causing massive overdose, the patient has a significantly reduced conscious state or respiratory arrest).

If small incremental intravenous doses of naloxone are appropriate for a patient with opioid-induced ventilatory impairment in palliative care, use:

If the intravenous route is not available, use:

The duration of action of naloxone is relatively short (15 to 30 minutes) compared to that of opioids, particularly long-acting opioids such as methadone or buprenorphine. Continuously observe the patient for indicators of opioid-induced ventilatory impairment because repeat administration or infusion of naloxone may be required. Seek specialist palliative care advice or call a poisons information centre (telephone 13 11 26 across Australia 24 hours a day).

For patients who have ongoing pain following an episode of opioid-induced ventilatory impairment, consider restarting the opioid at 50% of the previous dose once the patient’s sedation score is 0 or 1, and their respiratory rate is within normal limits for their age.

Naloxone is available for use in the community for patients at risk of opioid overdose; however, it is very rarely used by specialist palliative care services. ‘Take-home naloxone’ is available over-the-counter without prescription, and on prescription (subsidised through the Pharmaceutical Benefits Scheme [PBS]). Consider the potential benefits and harms of prescribing take-home naloxone, and the patient’s prognosis, preferences and goals of care—seek specialist palliative care advice.