Safety of ketamine in Australia mechanically ventilated intensive care unit spitalized patients by doctor Tom Niccol
Safety of ketamine in Australia ventilated intensive care unit spitalized patients with doctor Tom Niccol: Ketamine has been recommended for use as an opioid sparing agent to treat pain and discomfort in mechanically ventilated ICU patients. However, such a recommendation is only conditional, because of very low quality of evidence. This narrative scoping review focuses on current knowledge of the use of ketamine, concluding with a focus on mechanically ventilated adult patients in the ICU. Although incompletely understood, ketamine has multiple effects throughout the CNS. It blocks certain reflexes in the spinal cord and inhibits excitatory neurotransmission in selected areas of the brain. It functionally appears to dissociate the thalamus (which relays sensory impulses from the periphery) from the limbic cortex (involved in awareness of sensation). Find additional info at Tom Niccol Australia.
Mechanically ventilated patients account for about one-third of all admissions to the intensive care unit (ICU). Ketamine has been conditionally recommended to aid with analgesia in such patients, with low quality of evidence available to support this recommendation. We aimed to perform a narrative scoping review of the current knowledge of the use of ketamine, with a specific focus on mechanically ventilated ICU patients.
Ketamine used in anaesthetic doses (1–4.5 mg/kg intravenous) leads to dissociative anaesthesia: the patient appears conscious (eyes open, able to swallow) with preserved respiratory function and pharyngeal and laryngeal reflexes, but is unaware, unable to process or respond to sensory input. In addition, analgesia may also be mediated through serotonin and noradrenaline receptor activation and reuptake inhibition, as well as effects on δ, ϰ and μ opioid receptors. Unlike opioid medications, ketamine is thought to have little effect on gastrointestinal μ receptors, minimising the risk of constipation.
Methods: We searched MEDLINE and EMBASE for relevant articles. Bibliographies of retrieved articles were examined for references of potential relevance. We included studies that described the use of ketamine for postoperative and emergency department management of pain and in the critically unwell, mechanically ventilated population.
It is prudent to briefly review the data available on ketamine as an adjunct to analgesia in the non-ICU setting, which may provide some guidance as to the possible effectiveness when ketamine is used in mechanically ventilated ICU patients. Brinck and colleagues performed a Cochrane review of the use of ketamine for postoperative pain. The review included 130 randomised, double-blind, controlled trials of 8341 patients, of which 4588 received ketamine and 3753 were controls.
Results: There are few randomised controlled trials evaluating ketamine’s utility in the ICU. The evidence is predominantly retrospective and observational in nature and the results are heterogeneous. Available evidence is summarised in a descriptive manner, with a division made between high dose and low dose ketamine. Ketamine’s pharmacology and use as an analgesic agent outside of the ICU is briefly discussed, followed by evidence for use in the ICU setting, with particular emphasis on analgesia, sedation and intubation. Finally, data on adverse effects including delirium, coma, haemodynamic adverse effects, raised intracranial pressure, hypersalivation and laryngospasm are presented.
Raised intracranial pressure: Early observational studies suggested ketamine was associated with raised ICP in patients with space-occupying lesions 71, 72 and there were concerns with its use in traumatic and non-traumatic brain injury. However, to address these concerns, there have been several small randomised controlled trials of ketamine combined with midazolam versus narcotic combined with midazolam. Low dose. There are no studies using low dose ketamine to study its effects on raised ICP.
Conclusions: Ketamine is used in mechanically ventilated ICU patients with several potentially positive clinical effects. However, it has a significant side effect profile, which may limit its use in these patients. The role of low dose ketamine infusion in mechanically ventilated ICU patients is not well studied and requires investigation in high quality, prospective randomised trials.
