Background/Introduction: vasoplegic shock occurs up to 44% of patients after cardiopulmonary bypass surgery (CBS). Methylene blue (MB) among other vasopressors can increase mean arterial pressure after CBS. Retrospectively, receiving MB has been related to improved survival. The greatest response to MB is observed at the 8th hour of administration, as a significant decrease in the dose of vasopressors.
Purpose: to describe the prevalence and characteristics of MB non-responders among patients with vasoplegic shock after CBS.
Methods: All consecutive patients from January 2017 to May 2018 taken to CPB surgery and were alive at 48 hours of surgery where analysed retrospectively. All patients that received MB were included. Demographic characteristics, clinical and laboratory data was obtained from medical records. The dose of vasopressors received was summarized by vasoactive inotropic score (VIS). MB was systematically administered to patients who had received adequate fluid resuscitation and persisted hypotensive despite 0,4 µg/kg/min of norepinephrine plus 2,4 UI/hr of vasopressin and one inotropic (VIS > 40). Responders to methylene blue were defined as those with a reduction in VIS greater than 50% at the 8th hour after MB administration.
Results: Among 202 of patients included, 8 % (n = 16) patients developed vasoplegic shock and received MB. Most patients (62%, n = 10) were responders to MB. There was not significant demographic differences between responders vs non-responders, neither significant differences in the prevalence of known risks factors for vasoplegic shock. MB maximal hemodynamic response was observed at 8th hour form application (Table 1 and Figure 1.). MB responders had higher cardiac index and systemic vascular resistance index. There was no differences in incidence of infection between responders vs non-responders. Remarkable, non-responders had higher leukocytes count in the first 48 hours.
Conclusion: MB is an effective treatment of VS after cardiac surgery, but 40% of our cohort did not respond to therapy.