Unique Considerations for the Spinal Cord Injured Patient Undergoing Cardiac Surgery Utilizing Cardiopulmonary Bypass

A 37-year-old male with mitral valve regurgitation presented for mitral valve replacement. He has been a C5 quadriplegic for 13 years. The patient had been discharged 2 months before to this admission after a complicated hospital course for Staphylococcus aureus infection of the left hip. His course was complicated by adult respiratory distress syndrome (ARDS) requiring prolonged intubation, acute renal failure (ARF) requiring dialysis, 10-day coma, and bacterial endocarditis now requiring mitral valve replacement. After initial stabilization with antibiotics and gradual improvement of the multiorgan system failure, the patient presented for valve replacement and worsening congestive heart failure (CHF). Para- and quadriplegic patients rarely undergo cardiac surgery requiring cardiopulmonary bypass (CPB). The explanation for this low incidence of heart surgery in this patient population ranges from physiologic changes from the spinal cord injury to their relatively short life span. Therefore, there is no vast knowledge of how these patients with spinal cord injury will physiologically respond to CPB. Chronic paraplegia presents unique anesthetic and perfusion challenges. General anesthesia for a patient with prolonged spinal cord damage can be difficult because of dysreflexia, muscle wasting, and potassium changes with depolarizing muscle relaxants. For the perfusionist, chronic paraplegia also accentuates hemodynamic responses to nonpulsatile flow with low peripheral vascular resistance common and difficult to treat. Dramatic increases in circulating catecholamine levels are a secondary result of the initiation of CPB that can cause a hypo- and hypertensive state. Depending on the level of spinal cord injury, one might expect acute hypo- or hypertension with the various phases of open-heart surgery and CPB. A viscous circle may occur because the hypertensive state is exaggerated because of inhibitory signals not passed below the spinal cord lesion and, therefore, the vasoconstrictive reflex continues unabated. The attack usually occurs abruptly and can lead to cerebrovascular hemorrhage and death if not controlled. Fortunately, we found this patient did not develop mass autonomic dysreflexia and was not difficult to wean from CPB. The problems associated with spinal cord injury present potential complications to this patient population. Numerous triggering mechanisms may lead to a variety of clinical complications. Consideration of a response/treatment management plan for potential problems must be exercised by the surgical team

Optimising Cardiopulmonary Bypass Utilizing Continuous Oxygen Saturation Monitoring

Proper management of cardiopulmonary bypass requires the analysis of both arterial and venous blood gases at regular intervals, and is most critical during the rewarming phase. 3,4 In some hospitals blood gas results are received as long as 15 to 30 minutes after the sample is drawn. More frequent blood gas analysis or ideally continuous measurement of oxygen saturation allows the perfusionist to make continuous adjustments as the patient’s oxygen requirements change. Two hundred patients were selected for study. One hundred were perfused using regular periodic blood analyses. A second group of one hundred patients were perfused utilizing an in-line saturation meter. The blood flow rate was 6% lower during hypothermia and 5% lower while warm in the group utilizing the saturation meter. The total gas flow rate was reduced by 20% while cold and 16% while warm in the metered group. The CPB arterial and venous pO2 RANGES were reduced with the use of the oxygen saturation meter. The same make of hybrid oxygenator was utilized on all patients in both study groups. Based on the close correlation of the oxygen saturations afforded by the saturation meter and those measured by the blood gas laboratory, we found the Bentley Oxygen Saturation Meter reliable and accurate. It may help protect the patient from extremes in oxygenation and allows the perfusionist to regulate the oxygenator in the most precise and efficient operation

Cardiopulmonary bypass recommendations in adults: the northern New England experience.

Using a regional cardiopulmonary bypass (CPB) registry, we compared the practice of CPB at eight northern New England institutions to recently published recommendations. We examined CPB practice among 3597 adult patients undergoing isolated coronary artery bypass grafting surgery from January 2004 to June 2005. Registry variables were used to compare regional CPB practice to recommendations on topics of neurologic protection (pH management, avoidance of hyperthermia, minimizing return of pericardial suction blood, aortic assessment, arterial line filtration), maintenance of euglycemia, reduction of hemodilution, and attenuation of the inflammatory response. We report overall regional practice (regional minimum, maximum). All centers used alpha-stat pH management and arterial line filters. Avoidance of hyperthermia (temperature \u3c 37degrees C) was achieved during 23.4% of procedures (regional minimum, 1.5%; maximum, 83.2%). Minimizing return of pericardial suction blood was achieved in 23.7% of cases (0.7%, 93.6%). Aortic assessment was performed during 45.7% of procedures (1.3%, 98.9%). Maintenance of euglycemia (\u3c 200 mg/dL) was accomplished in 82.7% (57.1%, 97.9%) of cases. Hemodilution (hematocrit \u3c 23% on CPB) was lower for men 32.4% (20.6%, 52.3%) than women 77.9% (64.7% 88.9%). Men were less likely to receive red blood cell transfusions in the operating room (11.0%; 1.8%, 20.9%) than women (54.6%; 30.1%, 70.6%). In an effort to attenuate the inflammatory response, surface coated circuits were used in 83.3% of procedures (8.8%, 100%). During this time, gaps existed between regional CPB practice and recently published recommendations. We continue to prospectively measure CPB practice relating to these recommendations to monitor and improve the care provided to our patients