The Devil is in the details. This homily clearly applies to the use of major pain control drugs and the current opioid scourge causing death and ruined lives across much of the US.
Three American organizations representing anesthesiologists and pain-management specialists have generated new Consensus Guidelines on IV use of ketamine for acute pain management. Creation of the guidelines reflects the fact that ketamine can be effective — and often, a best choice – in specific settings. Once confined for the most part to veterinary use, ketamine infusions have become a mainstay of therapy in emergency care, in the perioperative period for patients with refractory pain, and in opioid-tolerant patients. But patient selection varies widely, as do treatment parameters, and monitoring.
According to the guidelines, subanesthetic ketamine is indicated primarily for patients undergoing surgery that is likely to result in severe postoperative pain — including thoracic and upper abdominal surgery, lower abdominal and intra-abdominal surgery, and orthopedic limb and spine surgery. The authors note that perioperative ketamine use has not been shown to be of benefit to patients undergoing such procedures as tonsillectomy and head and neck surgery that are associated with mild levels of pain
Ketamine may also be appropriate for surgical patients who are opioid-tolerant or opioid-dependent and also those with an acute exacerbation of a chronic pain condition. At least one study (there haven’t been many) showed that the use of ketamine in opioid-dependent patients undergoing major spine surgery resulted in a reduction in opioid use over 48 hour and six-week periods. Other studies have either not revealed a reduction in opioid usage in patients who received ketamine or have produced inconclusive findings. The authors note that “the studies suggest at least mild benefit for ketamine in the opioid-tolerant population…” and that “this benefit may be moderate.”
The guideline also suggests that ketamine may be a reasonable choice for patients at risk for respiratory depression associated with opioid use — especially those with obstructive sleep apnea. However, evidence for such a ketamine benefit has not yet been demonstrated in controlled studies.
The new guidelines also cover other major aspects of the clinical use of ketamine, including:
- As an adjunct to commonly employed opioid agents to achieve perioperative analgesia: The authors found that moderate evidence supports subanesthetic IV ketamine bolus doses and infusions as adjuncts to opioids in this setting.
- Contraindications to ketamine infusions for acute pain management: The guidelines note that ketamine should be avoided in the following patients:
- Those with poorly controlled cardiovascular disease
- Who are pregnant
- Who are acutely psychotic
- Who have severe hepatic dysfunction (eg, cirrhosis)
- Who have elevated intracranial pressure and intraocular pressure
Finally, the guidelines offer details on dosing and on whether there is evidence to support patient-controlled IV ketamine analgesia pain. You can find the details and answers here.