Ketamine as an Adjuvant in Spinal Anesthesia

Primary Considerations

The American Society of Anesthesiologists recommends that ketamine may be used cautiously as an adjuvant during spinal anesthesia, but its routine use is not recommended due to limited evidence of benefit and significant risk of postoperative confusion, particularly in elderly patients 1

Ketamine may counteract hypotension through sympathomimetic activity, which may help maintain blood pressure during neuraxial blockade 1
Ketamine has bronchodilation effects that could benefit patients with asthma or chronic obstructive pulmonary disease 2
Ketamine provides supplemental analgesia without respiratory depression when used in subanesthetic doses 3
The use of ketamine is associated with a significant risk of postoperative confusion, which is particularly problematic in elderly patients undergoing spinal anesthesia 1
Increased secretions may occur when ketamine is combined with other medications, potentially causing upper airway complications 2
No proven benefit for delirium prevention was found in the PODCAST trial, which included 672 patients, with increased hallucinations and nightmares in ketamine groups 4

For hip fracture surgery in elderly patients, ketamine should be used with extreme caution, if at all, due to the risk of postoperative confusion 1
Peripheral nerve blockade, such as fascia iliaca blocks, demonstrates clear benefit in reducing delirium incidence, severity, and duration compared to sham blocks 4
The American College of Anesthesiologists recommends that regional analgesia, including peripheral nerve blockade and intrathecal opioids, provides superior analgesia with better safety profiles for most patients undergoing spinal anesthesia 1, 4

If ketamine is deemed necessary, the lowest effective dose should be used to minimize adverse effects, with a recommended intravenous bolus of 0.2-0.5 mg/kg and continuous infusion of 2 mcg/kg/hour 1

To reduce emergence phenomena, minimize verbal, tactile, and visual stimulation during recovery, consider co-administration with benzodiazepines, and use lower doses in conjunction with other analgesics 1