Effects of Sevoflurane on Neonate Myocardium
Sevoflurane has direct myocardial depressant effects on neonatal myocardium, causing dose-dependent decreases in contractility and cardiac output, though it appears to have less pronounced negative inotropic effects compared to other volatile anesthetics like halothane.
Cardiovascular Effects of Sevoflurane in Neonates
- Sevoflurane, like all inhaled volatile anesthetics, causes depression of myocardial contractility and afterload reduction in the neonatal heart 1
- In neonatal rat ventricular myocytes, sevoflurane decreases beating rate and contractile amplitude in a concentration-dependent manner, though to a lesser extent than halothane 1
- The myocardial depressant effects of sevoflurane are mediated through reduction of sarcolemmal L-type Ca²⁺ channel current levels in immature hearts 1
- Sevoflurane depresses cardiac index and myocardial contractility in pediatric patients, but has less profound negative inotropic effects compared to halothane 2
Comparative Cardiac Effects Among Volatile Anesthetics
- The potency for suppression of contractile amplitude in neonatal myocardium follows the order: halothane >> isoflurane > sevoflurane 1
- When comparing volatile anesthetics at equivalent MAC values, sevoflurane maintains cardiac index and heart rate better than halothane in pediatric patients with congenital heart disease 2
- Sevoflurane has less pronounced hypotensive effects than halothane in children with congenital heart disease 2
- The blood-gas partition coefficient of sevoflurane in children is 0.66, which is markedly lower than those of isoflurane (1.25) and halothane (2.26), allowing for more rapid induction and emergence 3
Electrophysiological Effects
- Sevoflurane prolongs action potential duration in myocardial tissue without altering the peak amplitude or maximum depolarization rate 4
- The anesthetic markedly depresses the delayed outward K⁺ current while only slightly affecting the inwardly rectifying K⁺ current 4
- Sevoflurane depresses parasympathetic tone during induction in children, which can explain differences in heart rate changes between infants and children 5
- The withdrawal of parasympathetic tone is the main determinant for heart rate changes induced by sevoflurane in pediatric patients 5
Clinical Implications for Neonatal Anesthesia
- When intubation or invasive procedures are required in neonates, sevoflurane may cause direct myocardial depressant effects that can worsen hemodynamic status 6
- Ketamine with atropine premedication is suggested as an alternative for sedation and intubation in neonatal septic shock due to better cardiovascular stability 6
- In neonates with poor left ventricular function, the addition of nitrosovasodilators or type III phosphodiesterase inhibitors may be necessary when using volatile anesthetics like sevoflurane 6
- Volume loading based on clinical examination and blood pressure changes is important when using systemic vasodilators alongside sevoflurane in neonates 6
Monitoring Recommendations
- When using sevoflurane in neonates, monitoring should include pulse oximetry, blood gas analysis, continuous intra-arterial blood pressure, central venous pressure/O₂ saturation, and cardiac output 6
- Echocardiography is appropriate for monitoring myocardial function in neonates receiving sevoflurane, especially those with compromised cardiovascular status 6
- Monitoring for signs of fluid overload is essential, as diuretics or continuous renal replacement therapy may be needed in neonates who develop fluid overload while receiving anesthesia 6
Practical Considerations
- Avoid desflurane in neonates with upper respiratory tract infections, as it increases airway resistance more than sevoflurane 6
- In neonates with cardiovascular disease, starting with low concentrations (0.25-0.5 MAC) of sevoflurane and gradually increasing can help minimize hemodynamic fluctuations 7
- For neonates with congenital heart disease, sevoflurane may offer better hemodynamic stability than halothane, but careful titration is still necessary 2