What are the administration guidelines and precautions for ketamine (1mg/kg) in a patient undergoing a procedure requiring sedation or anesthesia, considering potential interactions and cardiovascular risks?

Ketamine 1mg/kg Administration

Ketamine 1mg/kg IV is below the recommended induction dose and will likely result in inadequate sedation for most procedures requiring anesthesia. The FDA-approved induction dose ranges from 1-4.5 mg/kg IV, with 2 mg/kg being the average dose required to produce 5-10 minutes of surgical anesthesia 1. Using only 1mg/kg significantly increases the likelihood of requiring supplemental doses—studies show 54% of patients need additional ketamine at 1mg/kg compared to only 5.5% at 1.5mg/kg 2.

Recommended Dosing Strategy

For procedural sedation requiring anesthesia, administer 1.5-2 mg/kg IV as the initial dose rather than 1mg/kg 2, 1. This provides:

• Adequate sedation in 94.5% of patients without supplemental dosing 2
• Onset of action within 30-96 seconds 2
• Duration of 5-10 minutes of surgical anesthesia 1

If 1mg/kg has already been administered and proves inadequate, supplement with additional increments of one-half to the full induction dose as needed 1.

Administration Technique

Administer ketamine slowly over 60 seconds when giving IV 1. Rapid administration causes:

• Respiratory depression 1
• Enhanced vasopressor response 1

The 100 mg/mL concentration must be diluted 1:1 with sterile water, normal saline, or 5% dextrose before IV administration 1. Use immediately after dilution 1.

Critical Cardiovascular Contraindications

Avoid ketamine entirely in patients with ischemic heart disease, cerebrovascular disease, or uncontrolled hypertension 3, 2. Ketamine produces dose-dependent increases in:

• Heart rate 3
• Blood pressure 3
• Cardiac output 3
• Myocardial oxygen demand 4

These effects occur through sympathetic nervous system stimulation and are "potentially dangerous" in cardiovascular disease 3.

Essential Monitoring Requirements

Continuous vital sign monitoring is mandatory, including 2, 1:

• Oxygen saturation
• Heart rate
• Blood pressure
• Capnography when available

Emergency airway equipment must be immediately available 1. While ketamine preserves airway reflexes better than other sedatives, laryngospasm (0.9-1.4% incidence) and airway obstruction can occur 5, 4.

Managing Emergence Reactions

Administer a benzodiazepine (midazolam 0.05-0.1 mg/kg) to prevent emergence phenomena 2, 1. Without prophylaxis:

• 10-30% of adults experience emergence reactions (hallucinations, vivid dreams, delirium) 3
• Recovery agitation occurs in 17.6% of patients 2

Midazolam reduces recovery agitation from 35.7% to 5.7% in patients over 10 years old 2.

Additional Contraindications

Beyond cardiovascular disease, avoid ketamine in patients with 5, 1:

• Active psychosis
• Severe hepatic dysfunction
• Elevated intracranial or intraocular pressure
• Pregnancy

Pre-medication Considerations

Administer an antisialagogue prior to ketamine induction due to potential for excessive salivation 1. This is particularly important for airway management.

Expected Adverse Events at Therapeutic Doses

Common side effects include 2, 5:

• Emesis without aspiration: 6.7% of cases
• Mild recovery agitation: 17.6% of cases
• Transient hypoxemia: 1.6-7.3% of cases (typically responsive to supplemental oxygen)
• Brief apnea around time of injection 4

Serious cardiorespiratory adverse events are rare despite these common minor effects 4.

Recovery Expectations

Average recovery time is approximately 84 minutes (range 22-215 minutes) after IV ketamine administration 2. Higher total doses result in longer recovery times 1.