A Study of the Effectiveness of Lidocaine to Treat Severe Pulmonary Vascular Constriction induced by Protamine

ABSTRACT

Background: Protamine neutralises heparin a?er separa?on from cardiopulmonary bypass. This study aimed to evaluate the effects of lidocaine on protamine induced pulmonary vascular constric?on in paediatric cardiothoracic surgery. Methods: This was a single-centre, prospec?ve, double-blind and randomised study conducted among eighty pediatric pa?ents with acyano?c congenital cardiac disease, scheduled for elec?ve on-pump cardiac surgery under general anaesthesia. In the study, the par?cipants were divided into four groups Group NPHL- nonpulmonary hypertension with lidocaine precondi?oning, group NPHS- nonpulmonary hypertension with normal saline (as placebo), group PHL- pulmonary hypertension with lidocaine precondi?oning, and group PHS- pulmonary hypertension with normal saline (as placebo). Results: Pulmonary vasoconstric?on occurred in 11.25% of cases a?er protamine administra?on. Both the NPHS and PHS groups exhibited an increase in mean airway pressure (Paw), Respiratory index (RI), alveolar-arterial oxygen difference (A-aDO2), pulmonary artery pressure (PAP) and decreased dynamic pulmonary compliance (Cydn) and oxygen index (OI) a?er protamine administra?on. However, these changes were not observed in the NPHL and PHL groups with lidocaine precondi?oning. Plasma levels of TXB2 in the NPHS and PHS groups were higher than the NPHL and PHL groups, but 6-keto-PGF1 alpha levels were lower in the NPHS and PHS groups than in the NPHL and PHL groups. Conclusion: In congenital heart disease, repair without cardiopulmonary bypass is not possible in most cases. Prior to reversing heparin with protamine, precondi?oning lidocaine reverses protamine-induced pulmonary vasoconstric?on and improves lung func?on.