Hemodynamic Effect of Dexmedetomidine Alone With Dexmedetomidine Plus Ketamine Combination in CABG

Hemodynamic Instability

Cardiac Surgery, Dexmedetomidine, Extubation, Hemodynamics, Ketamine, Fentanyl

In post cardiac surgery, many cardiovascular and other complications may occur that lead to increase in mortality and hospital stays. Meticulous perioperative management is important to avoid these adverse events. Tachycardia is the main cause of post coronary artery bypass graft (CABG) myocardial ischemia which can be decreased by sedation and analgesia.

Dexmedetomidine is a highly specific alpha 2 adrenoreceptor agonist. Its sedative effect results from stimulation of alpha 2 adrenoreceptors in the central nervous system (in the locus coeruleus) independent of GABA system contrary to other drugs.Dexmedetomidine has better sedative effect and similar respiratory and hemodynamic effects to midazolam. It does not depress respiratory drive or decrease arterial oxygen saturation so intravenous (IV) continuous sedation with dexmedetomidine does not change the normal course of ventilator weaning and extubation. It produces a unique EEG pattern of sleep that closely resembles that of normal physiological sleep that allows easy arousal. Dexmedetomidine also has analgesic effect. All these properties make dexmedetomidine a first line drug for the cooperative sedation management in the Intensive Care Unit (ICU). Ketamine is a phencyclidine nonbarbiturate derivative that binds with N methyl d aspartate and sigma opioid receptors to produce dissociative anesthesia, analgesia, and amnesia with little or no respiratory or cardiovascular depression. Ketamine inhibits endothelial nitric oxide production leading to positive inotropic action and vasoconstriction which preserves hemodynamic stability. Dexmedetomidine can effectively and safely attenuate the ketamine induced hemodynamic pressor response and psychomimetic effects. Dexmedetomidine expected to prevent the tachycardia, hypertension, salivation, and emergence phenomena associated with ketamine. Ketamine may prevent the bradycardia and hypotension that have been reported with dexmedetomidine. Review of literature has shown that there are very few studies present on the comparison of combination of Ketamine and dexmedetomidine with dexmedetomidine alone especially in post cardiac surgery patients and therefore further studies are required to ascertain the role of dexmedetomidine in terms of hemodynamic effects after cardiac surgery.

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