Increasing mean arterial blood pressure has no effect on jugular venous oxygen saturation in insulin-dependent patients during tepid cardiopulmonary bypass

Association between cerebrovascular carbon dioxide reactivity and postoperative short-term and long-term cognitive dysfunction in patients with diabetes mellitus

PURPOSE

Our intent was to identify whether cerebrovascular CO(2) reactivity in diabetic patients is a risk factor for postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery.

METHODS

One hundred twenty-four diabetic patients undergoing elective CABG were studied and analyzed. Diabetic patients were divided into three groups: normal CO(2) reactivity group (above 5%/mmHg), medium CO(2) reactivity group (between 5 and 3%/mmHg), or impaired CO(2) reactivity group (below 3%/mmHg). After the induction of anesthesia and before the start of surgery, cerebrovascular CO(2) reactivity was measured for all patients. Hemodynamic parameters (arterial and jugular venous blood gas values) were measured during cardiopulmonary bypass. All patients underwent a battery of neurological and neuropsychological tests the day before surgery, 7 days after surgery, and 6 months after surgery.

RESULTS

At 7 days, the rate of cognitive dysfunction in the impaired CO(2) group was higher than in the other three groups (normal, 30%; medium, 25%; impaired, 57%; *P < 0.01 compared with the other groups). In contrast, at 6 months postoperatively, no significant difference in the rate of cognitive dysfunction was found among the three groups. Age, hypertension, CO(2) reactivity, the duration for which jugular venous oxygen saturation (SjvO(2)) was less than 50%, ascending aorta atherosclerosis, diabetic retinopathy, and insulin therapy were independent predictors of short-term cognitive dysfunction in diabetic patients, and HbA1c, diabetic retinopathy, and insulin therapy were independent predictors of long-term cognitive dysfunction in diabetic patients.

CONCLUSIONS

We found that impaired cerebrovascular CO(2) reactivity was associated with postoperative short-term cognitive dysfunction in diabetic patients.

Anesthetic considerations in diabetic patients. Part II: intraoperative and postoperative management of patients with diabetes mellitus

Some studies have reported that tight glycemic control in diabetic patients undergoing major surgery improves perioperative morbidity and mortality rates. Recently, however, large randomized studies have shown such control increases the mortality rate, since aggressive glycemic control induces more frequent incidences of hypoglycemia. Diabetic patients have cerebral complications during the perioperative period more often than their nondiabetic counterparts. Further, anesthetic agents have some effects on cerebral circulation and cerebrovascular carbon dioxide reactivity. Hence, anesthesiologists should have adequate knowledge about anesthetic agents that maintain the integrity of the cerebral circulation. Patients with diabetes mellitus (DM) have an increased susceptibility to perioperative infections. Recent work confirmed that a combination of intravenous and subcutaneous insulin as a glucose management strategy had beneficial effects identical with intravenous insulin therapy alone on the reduction of infection rates during the postoperative period.

Effects of nicardipine-induced hypotension on cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sevoflurane anesthesia

PURPOSE

The purpose of this study was to examine the effects of nicardipine-induced hypotension on cerebrovascular CO2 reactivity in patients with diabetes mellitus under sevoflurane anesthesia.

METHODS

Nineteen diabetic patients, and 11 nondiabetic patients (serving as controls), undergoing elective orthopedic, cardiovascular, or thoracic surgery were included in the study. The diabetic patients were divided into three groups according to the antidiabetic therapy they were receiving, i.e., diet therapy (n = 6), oral antidiabetic drugs (n = 7), and insulin (n = 6). Anesthesia was maintained with 1.0 minimum alveolar concentration of sevoflurane. Absolute and relative cerebrovascular CO2 reactivity was calculated using a 2.5-MHz pulsed transcranial Doppler (TCD) probe for the continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). The cerebrovascular CO2 reactivity was measured both at baseline and during hypotension by increasing the ventilatory frequency by 4 to 7 breaths.min(-1). Nicardipine was used to induce hypotension.

RESULTS

We found that values for the Bispectral index (BSI), baseline mean blood pressure, endtidal CO2 (Pet(CO2)), and Vmca were essentially identical in all patients, irrespective of the type of antidiabetic treatment being taken. Values for absolute and relative CO2 reactivity in insulin-dependent patients, at both baseline blood pressure and during hypotension, were lower than those in patients in the antidiabetic drug, diet, and control groups (during hypotension, absolute CO2 reactivity: diet group: 3.2 +/- 0.9; oral antidiabetic drug group: 3.2 +/- 0.7; insulin group: 1.5 +/- 0.6; control group: 3.4 +/- 0.8 cm.s(-1).mmHg(-1), [P < 0.05 insulin group vs the other groups]; relative CO2 reactivity: diet group, 6.3 +/- 1.0; oral antidiabetic drug group, 6.5 +/- 0.8; insulin group, 3.5 +/- 0.8; control group, 6.5 +/- 0.7%.mmHg(-1), [P < 0.05 insulin group vs the other groups].

CONCLUSION

We concluded that cerebrovascular CO2 reactivity in insulin-dependent patients is impaired during nicardipine-induced hypotension under sevoflurane anesthesia.

Factors associated with postoperative cognitive dysfunction in patients undergoing cardiac surgery

PURPOSE

Central nervous system complications continue to be major causes of morbidity and mortality after cardiac surgery. The purpose of this study was to identify the risk factors for postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery.

METHODS

Eighty-eight patients scheduled for elective CABG were studied. After the induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb for the continuous monitoring of jugular venous oxygen hemoglobin saturation (SjvO(2)). The hemodynamic parameters and arterial and jugular venous blood gases were measured during cardiopulmonary bypass (CPB). All patients underwent a battery of neurological and neuropsychological tests one day before the operation and at 6 months after the operation.

RESULTS

The incidence of a cognitive decline at 6 months was 24/88 (27.3%). Greater age (P = 0.04), the presence of renal failure (P < 0.001), and diabetes mellitus (P < 0.001) were more frequent in the patients with postoperative cognitive dysfunction at 6 months after the operation than in patients without cognitive dysfunction. Age (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.0-1.7; P = 0.04), diabetes mellitus (OR, 1.8; 95% CI, 1.2-2.4; P < 0.01), and presence of renal failure (OR, 2.8; 95% CI, 2.4-4.3; P < 0.01) were associated with cognitive impairment at 6 months postoperatively. However, there was no relationship between the presence of atherosclerosis in the ascending aorta and postoperative cognitive dysfunction after CABG surgery.

CONCLUSIONS

A greater age, diabetes mellitus, and renal failure were found to be risk factors for development of cognitive impairment at 6 months after CABG with CPB.

Analysis of the factors related to a decrease in jugular venous oxygen saturation in patients with diabetes mellitus during normothermic cardiopulmonary bypass

PURPOSE

We sought to examine what factors, including cerebrovascular carbon dioxide (CO(2)) reactivity, are related to a decrease in internal jugular venous oxygen saturation (SjvO(2)) during normothermic cardiopulmonary bypass (CPB) in patients with diabetes mellitus.

METHODS

Twenty-three diabetic patients scheduled to undergo elective coronary artery bypass grafting were studied. As a control, 27 age-matched control patients without diabetes mellitus were also examined. After the induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor SjvO(2). Arterial and jugular venous blood gases were measured during CPB. The cerebrovascular CO(2) reactivity was measured after the induction of anesthesia and before the start of surgery using a 2.5-MHz pulsed transcranial Doppler probe.

RESULTS

The SjvO(2) values in the diabetic group were lower than those in the control group at the initiation of CPB and at 20, 40, and 60 min after the start of CPB. The values for pre- and post-CO(2) reactivity in the control group did not significantly differ (pre-CPB: 4.8% +/- 2.3% mmHg(-1); post-CPB: 5.9% +/- 4.4% mmHg(-1)). In contrast, the values for CO(2) reactivity were lower post CPB than pre-CPB in the diabetic group (Pre-CPB: 6.3% +/- 2.9% mmHg(-1); post-CPB: 4.7% +/- 2.6% mmHg(-1); P < 0.05). In the diabetic group, glycosylated hemoglobin A1c (HbA1c) is considered to be a factor related to a decrease in SjvO(2) during CPB.

CONCLUSIONS

Cerebrovascular CO(2) reactivity in diabetic patients decreased after the cessation of CPB but not in the control patients. In addition, HbA1c is also thought to be a factor related to a decrease in SjvO(2) in diabetic patients.