Muhammad Zameer, Shahab Naqvi.
Prolonged Refractory Hypotension in Cardiac Surgery after initiation of Cardiopulmonary Bypass.
Pak Armed Forces Med J Jan ;52(2):227-8.

A 65 year old, 75 kg man with a history of class IV angina was scheduled for elective coronary artery revascularization. Previous medical history was significant for coronary artery disease, hypertension (treated with diltiazem 120mg twice daily and captopril 25mg twice daily) and type-II diabetes Mellitus. Physical examination was unremarkable. Cardiac Catheterization revealed an ejection fraction of 70 percent and severe three vessel coronary artery disease. The patient had his last captopril dose at 10:00 PM, a night before operation and was brought to the operating theatre at 07:00 AM. Premedication with promethazine 25mg intramuscularly, morphine 0.1 mg/kg intramuscularly, and lorazepam 1 mg orally was given 1 hour before surgery. After insertion of a 16G peripheral venous catheter and a right radial artery catheter, anesthesia was induced with Propofol 100mg, and Morphine 15mg, muscle relaxation was facilitated by 8mg of Pancuronium. Propofol infusion 5-8 ml per hour and pancuronium were supplemented for maintenance of anesthesia. Haemaccel and cefotaxime 1g, were given as routine at induction of anesthesia without any adverse reaction. The haemodynamic stability was notable in the Pre-CPB period (arterial pressure 130/65mmHg, heart rate 55-65bpm). The CPB circuit was primed with Ringer`s lactate (1000ml), mannitol 20% (50ml), and Hemaccel (500ml). A mean arterial pressure of 20 to 25mmHg (profound hypotension) was evident on initiation of CPB. This hypotension was refractory to repeated boluses of 30-50 microgram of adrenaline, the patient received a total of 1.6mg of adrenaline during the CPB in an attempt to keep the MAP > 40mmHg. Because of the lack of response, intravenous nor-adrenaline was started (0.05 microgram/kg/min upto 0.2 microgram/kg/min within 15 minutes). The patient remained hypotensive (mean arterial pressure 25 mmHg) and became oliguric despite therapy with frusemide (120mg). Pump flow was increased from 2.4 to 2.7 l/min/m2 without benefit. The lowest hematcrit on CPB was 22%. On weaning from CPB, hypotension persisted (Systolic BP 70mmHg) despite treatment with nor-adrenaline (0.1 microgram/kgHg) and intravenous fluids (1500ml). Continued ..

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