Role of Vitamin C in Cardiac Vasoplegia After Cardiopulmonary Bypass

This is a parallel group double-blind, randomized-controlled trial with 1:1 randomization ratio which will be conducted over a period of 6 months to study the effect of vitamin C administration on the amount of noradrenaline given post-operatively to patients after CPB. Two groups will be included; Group (A) patients undergoing open heart surgeries who will receive IV ascorbic acid (treatment group) and Group (B) patients undergoing open heart surgeries who will not receive ascorbic acid or will receive a placebo (control group). Each patient will be subjected to assessments of the doses of noradrenaline given from the end of surgery until weaning as well as hemodynamics in the first 2 hours and then at intervals of 6 hours up to 3 days following surgery.

Background and Rationale:

Cardiac vasoplegia is a known phenomenon after cardiopulmonary bypass (CPB) occurring in up to 44% of patients. Severe forms of such condition refractory to vasopressors are associated with poor outcomes. New agents e.g. ascorbic acid that can alter the systemic vascular resistance in cardiac vasoplegia have been suggested as an attempt to avoid or at least reduce the use of IV vasopressors and their induced systemic hypo-perfusion.

Objectives :

* Primary objective: to study the effect of vitamin C administration on the amount of noradrenaline given post-operatively to patients after CPB
* Secondary objectives: to study the effect of vitamin C administration on the time to weaning from noradrenaline

Study population \& Sample size :

Patients undergoing cardiac surgeries with CPB having risk factors for cardiac vasoplegia like diabetes mellitus and chronic renal failure.

50 patients will be needed in each group (treatment and control)

Study Design :

A parallel group double-blind, randomized-controlled trial, with 1:1 randomization ratio 2 groups will be included;

-Group (A) patients undergoing open heart surgeries who will receive IV ascorbic acid. -Group (B) patients undergoing open heart surgeries who will not receive ascorbic acid or will receive a placebo (Control Group).

Methods :

Each patient will be subjected to the following assessments:

-Pre-operative patient characteristics: demographic data, co-morbidities, pre-operative echo findings,... -Intra-operative details: procedures, time parameters,... the doses of noradrenaline given from the end of surgery until weaning or death and hemodynamics in the first 2 hours and then at intervals of 6 hours up to 3 days following surgery. -Postoperative data: echo parameters, patient outcome, time of discharge,...

Outcome parameter (s):

-Primary outcome: the area under the dose-time curve of noradrenaline -Secondary outcome measures: the duration of vasopressor (noradrenaline) infusion till weaning up to 3 days following surgery.

Eligibility Criteria:
Inclusion Criteria:

* Patients undergoing cardiac surgeries with CPB having risk factors for cardiac vasoplegia like diabetes mellitus and chronic renal failure.

Exclusion Criteria:

* Patients who undergo surgeries without cardiopulmonary bypass (off-pump)
* Patients undergoing surgeries for congenital cardiac disease
* Patients performing heart transplantation and combined cardiac surgeries
* Patients with low pre-operative left ventricular ejection fraction (LVEF)
* Patients refusing to participate
* Patients who receive vasopressors other than noradrenaline