Comparison between sevoflurane bolus and esmolol bolus for attenuating hemodynamic response to pneumoperitoneum in laparoscopic surgery- A prospective randomised study.

The pneumoperitoneum created using carbon dioxide (CO2) in laparoscopic surgery leads to stimulation of the sympathetic nervous system resulting in pathophysiological changes characterized by an increase in Heart rate, arterial pressure, systemic and pulmonary vascular resistance (SVR and PVR) immediately after the beginning of intra-abdominal insufflation.  It can be a risk factor for adverse cardiologic events in patients undergoing laparoscopic surgeries [1–4]. In addition, the anesthetic agents alter the cardiopulmonary function significantly [5].  Different pharmacological agents such as a2 adrenergic agonists, magnesium sulfate [6], beta-blockers [7], and opioids [8] are used to attenuate circulatory response due to pneumoperitoneum.

Esmolol, an ultra short-acting cardio-selective b1-receptor antagonist, has been shown to blunt hemodynamic responses to perioperative and intraoperative noxious stimuli due to overshooting sympathetic activity[9]. The heart rate and blood pressure-lowering effect start immediately after intravenous administration of esmolol and the effects are short-lasting as its elimination half-life is 9 minutes. Different doses of esmolol were used for attenuating surgical response such as ranging from 0.3mg/kg -1.5 mg/kg but doses ranging from 0.5-0.6mg/kg were found safe and effective.[10]

A general anesthetic must provide adequate hypnosis and analgesia as well as block motor and sympathetic responses which can be achieved by volatile anesthetics, local anesthetics acting on peripheral nerves, or an opioid acting on the spinal cord, midbrain, thalamus, and higher centers [11]. Moreover, the ideal anesthetic should suppress the hemodynamic responses to surgery without causing significant cardiovascular depression [12].

An inhalation bolus minimizes this hysteresis through optimal use of the anesthesia apparatus, vaporizer setting, and fresh gas flow. To reach the desired anesthetic concentration without affecting normocapnia, the anesthesiologist may increase the inspired drug concentration, and if working with a closed circuit, the fresh gas may also be increased. There is usually a delay between a change in the vaporizer setting and the onset/offset of the desired clinical effect [13]. Low blood/gas solubility, absence of airway irritation, ease of titration, and cardiovascular stability make sevoflurane suitable for use when considering an inhalation bolus [14,15].

Hypothetical question: Whether Sevoflurane when given as a bolus dose is comparable to a bolus dose of esmolol in controlling hemodynamic response to surgical stress (pneumoperitoneum) in laparoscopic surgery?.