Ketamine

Used for:

• Short-term procedures (e.g., fracture reductions, dislocations, wound repair)

• Patients at high risk of bronchospasm (e.g., asthma)

• Hemodynamically unstable patients 

Mechanism:

• Achieves sedation through N-methyl-D-aspartate (NDMA) receptor antagonism. 

• Creates a dissociative state and produces analgesia through partial agonism of opiate mu-receptors.

CNS Effects:

• Increases cerebral oxygen consumption and blood flow: Unclear if ketamine increases intracranial pressure.

Cardiovascular (CV) Effects: 

• Increases BP and HR: Induces central release of endogenous catecholamines.

Respiratory Effects:

• Bronchodilation: Upper airway skeletal muscle tone maintained, less prone to airway obstruction; laryngeal reflexes intact, less risk of aspiration

• Decreases TV and RR: Inhibits CNS sensitivity to hypercapnia. 

Adverse Effects:

• PONV, dizziness 

• Restlessness and agitation common on emergence

Contraindications:

• Patients with low tolerance to acute increases in BP (e.g., ischemic heart disease, aortic dissection, known aneurysms) 

• Patients at risk of acutely increased intracranial pressure