Rose Christopherson

Perioperative Morbidity in Patients Randomized to Epidural or General Anesthesia for Lower Extremity Vascular Surgery

Background:Perioperative morbidity may be modifiable in high risk patients by the anesthesiologists choice of either regional or general anesthesia. This clinical trial compared outcomes between epidural (EA) and general (GA) anesthesia/analgesia regimens In a group of patients at high risk for cardiac and other morbidity who were undergoing similarly stressful surgical procedures. Methods:One hundred patients scheduled for elective vascular reconstruction of the lower extremities were randomized to receive either EA for surgery followed by epidural analgesia, or GA for surgery followed by intravenous patient-controlled analgesia. Hemodynamic monitoring, blood pressure, and heart rate limits were determined prior to randomization. Management of anesthesia in the immediate postoperative period was standardized. The data collected included continuous electrocardiographic monitoring from the day before surgery through the third postoperative day, serial electrocardiograms, and cardiac enzymes. Cardiac ischemia, myocardial infarction, unstable angina, and cardiac death were identified by a cardiologist blinded to the type of anesthesia received. Other major morbidity was determined at the time of hospital discharge and at 1 and 6 months after surgery. Results:Eleven patients who received GA required regrafting or an embolectomy during their hospital stay, compared with two patients who received EA. This association of GA with reoperation remained significant after adjustment for baseline differences. Cardiac outcomes were similar in the two groups with respect to perioperative death (1 EA and 1 GA), death within 6 months (4 EA and 3 GA), nonfatal myocardial infarction within 7 days (2 EA and 2 GA), unstable angina (0 EA and 2 GA), and myocardial ischemia following randomization (17 EA and 23 GA). Rates of major infections in the two groups (1 EA and 2 GA), renal failure (3 EA and 3 GA), and pulmonary complications (3 EA and 7 GA) also were similar. Conclusions:Carefully conducted epidural and general anesthesia appear to be associated with comparable rates of cardiac and most other morbidity in patients undergoing lower extremity vascular surgery. However, compared with general anesthesia, epidural anesthesia is associated with a lower incidence of reoperatlon for inadequate tissue perfusion and, therefore, may be advantageous for this surgical population.

Unintentional Hypothermia Is Associated with Postoperative Myocardial Ischemia

BackgroundHypothermia occurs commonly during surgery and can be associated with increased metabolic demands during rewarming in the postoperative period. Although cardiac complications remain the leading cause of morbidity after anesthesia and surgery, the relationship between unintentional hypothermia and myocardial ischemia during the perioperative period has not been studied. MethodsOne hundred patients undergoing lower extremity vascular reconstruction received continuous Hotter monitoring throughout the first 24 h postoperatively. Myocardial ischemia was determined by a cardiologist masked to clinical variables. The patients sublingual temperature on arrival at the intensive care unit immediately after the surgical procedure was used to divide the patients into two groups: hypothermic (temperature, < 35°C; n = 33) and normothermic (temperature, ≤ 35°C; n = 67). The relationship between unintentional hypothermia and myocardial ischemia occurring during the first postoperative day was evaluated by univariate and multivariate analyses. ResultsA greater percentage of patients had electrocardiographic changes consistent with myocardial ischemia in the hypothermic group (36%, 12 of 33) compared with those in the normothermic group (13%, 9 of 67, P = 0.008). Preoperative risk factors for perioperative cardiac morbidity were similar between the two groups, except for patient age. The mean age was 70 ± 2 yr and 62 ± 1 yr in the hypothermic and normothermic groups, respectively (P = 0.001). When subgroup and multivariate analyses were used to adjust for differences in age, temperature remained an independent predictor of ischemia (odds ratio, 1.82 per degree Celsius; 95% confidence interval, 1.09–3.02). The incidence of postoperative angina was greater in the hypothermic group (18%, 6 of 33) than in the normothermic group (1.5%, 1 of 67, P = 0.002). The incidence of PaO2 < 80 mmHg in the arterial blood was greater in the hypothermic group (52%, 17 of 33) than in the normothermic group (30%, 20 of 67, P = 0.03). ConclusionsUnintentional hypothermia is associated with myocardial ischemia, angina, and PaO2 < 80 mmHg during the early postoperative period in patients undergoing lower extremity vascular surgery.

The effects of different anesthetic regimens on fibrinolysis and the development of postoperative arterial thrombosis

Background:The purpose of this clinical trial was to compare the effects of different anesthetic and analgesic regimens on hemostatic function and postoperative arterial thrombotic complications. Methods:Ninety-five patients scheduled for elective lower extremity vascular reconstruction were randomized to receive either epidural anesthesia followed by epidural fentanyl (RA) or general anesthesia followed by intravenous morphine (GA). Intraoperative and postoperative care were controlled by protocol using predetermined limits for heart rate, blood pressure, and other monitoring criteria. Data collection included serial physical examinations, electrocardiograms, and cardiac isoenzymes to detect arterial thrombosis (defined as unstable angina, myocardial infarction, or vascular graft occlusion requiring reoperation). Fibrinogen, plasminogen activator inhibitor-1 (PAI-1), and D-dimer levels were measured preoperatively and at 24 and 72 h postoperatively. Results:Preoperative fibrinogen levels were similar in both groups, remained unchanged after 24 h, and increased equally (45%) in the first 72 h postoperatively. PAI-1 levels in the GA group increased from 13.6 ± 2.1 activity units (AU)/ml to 20.2 ± 2.6 AU/ml at 24 h and returned to baseline at 72 h. In contrast, PAI-1 levels in the RA group remained unchanged over time. Twenty-two of 95 patients (23%) had postoperative arterial thrombosis, 17 of whom had received GA and 5 of whom, RA. Preoperative PAI-1 levels were higher in patients who developed postoperative arterial thrombosis (20.5 ± 3.6 AU/ml vs. 11.2 ± 1.4 AU/ml). Multiple logistic regression analysis indicated that GA and preoperative PAI-1 levels were predictive of postoperative arterial thrombotic complications. Conclusions:Impaired fibrinolysis may be related causally to postoperative arterial thrombosis. Because RA combined with epidural fentanyl analgesia appears to prevent postoperative inhibition of fibrinolysis, this form of perioperative management may decrease the risk of arterial thrombotic complications in patients undergoing lower extremity revascularization.

Epidural versus general anesthesia, ambient operating room temperature, and patient age as predictors of inadvertent hypothermia.

To elucidate the multifactorial nature of perioperative changes in body temperature, the influence of several clinical variables, including anesthetic technique, ambient operating room temperature, and age, were evaluated. Perioperative oral sublingual temperatures were measured in 97 patients undergoing lower extremity vascular surgery randomized to receive either general (GA) or epidural (EA) anesthesia. Surgery and anesthesia were performed in operating rooms (OR) with a relatively warm mean ambient temperature (24.5 +/- 0.4 degrees C) (GA, n = 30; EA, n = 33) or relatively cold mean ambient temperature (21.3 +/- 0.3 degrees C) (GA, n = 21; EA, n = 13). Patients were 35-94 yr old, with a mean age of 64.5 +/- 1.1 yr. A regression analysis was performed to determine the variables that correlated with intraoperative decrease in temperature and postoperative rewarming rate. The major correlates of greater intraoperative decrease in temperature were 1) GA (P = 0.003); 2) cold ambient OR temperature (P = 0.07); and 3) advancing patient age (P = 0.03). There was significant interaction between ambient OR temperature and type of anesthesia (P = 0.03): there was a greater intraoperative decrease in temperature with GA compared to EA in a cold OR but a similar decrease with GA and EA in a warm OR. The data also suggest an interaction between type of anesthesia and patient age (P = 0.06), showing a greater decrease in temperature with GA compared to EA in the younger patients, but a similar decrease between GA and EA in older patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term survival after colon cancer surgery: a variation associated with choice of anesthesia.

BACKGROUND: A previously published clinical trial of epidural-supplemented versus general anesthesia, Veterans Affairs Cooperative Study No. 345, showed no difference in 30-day mortality and morbidity rates between the two treatments. We hypothesized that long-term postoperative survival would be increased by epidural anesthesia/analgesia supplementation during colon cancer resection. METHODS: We studied long-term survival after resection of colon cancer in a trial of general anesthesia with and without epidural anesthesia and analgesia supplementation for resection of colon cancer in Veterans Affairs Cooperative Study No. 345. Cox and log-normal survival models were used to test the effects of pathological stage, type of anesthesia and other covariates on survival in 177 patients. RESULTS: The presence of distant metastases had the greatest effect on survival. Thus, analyses were performed separately for patients with and without metastases. For those without metastasis, the hazard ratio for the treatment effects changed at 1.46 years. Before 1.46 years, epidural supplementation was associated with improved survival (P = 0.012), while later, the type of anesthesia did not appear to affect survival (P = 0.27). Hypertension was associated with poorer survival (P = 0.029), as was alcoholism in patients who received epidural anesthesia (P = 0.014). Survival of patients with metastases was unaffected by type of anesthesia. There was a significant age by hypertension interaction (P = 0.002). Patients survived longer if they were hypertensive, but had reduced survival if they were older than 66 years and hypertensive. CONCLUSION: Epidural supplementation was associated with enhanced survival among patients without metastases before 1.46 years. Epidural anesthesia had no effect on survival of patients with metastases. Additional studies to confirm or refute these findings are warranted.

Determinants of Catecholamine and Cortisol Responses to Lower Extremity Revascularization

BackgroundSurgical trauma elicits diffuse changes in hormonal secretion and autonomic nervous system activity. Despite studies demonstrating modulation of the stress response by different anesthetic/analgesic regimens, little is known regarding the determinants of catecholamine and cortisol responses to surgery. MethodsPlasma catecholamines and cortisol secretion data were obtained from 60 patients undergoing lower extremity revascularization. Patients were randomized to receive either general anesthesia combined with patient-controlled intravenous morphine (GA) or epidural anesthesia combined with epidural fentanyl analgesia (RA). All aspects of intra-and postoperative clinical care were defined by written protocol. Plasma catecholamines were measured before Induction, intraoperatively, and for the first 18 h postoperatively (by HPLC). Urine cortisol was measured intra-and postoperatively using RIA. Data were evaluated using univariate and multivariate analyses to evaluate demographic and perioperative variables as determinants of stress hormone secretion. ResultsPlasma catecholamines Increased during skin closure in the GA group, and remained higher relative to the RA group in the postoperative period. Multivariate analysis indicated that age and anesthetic regimen predicted increases in catecholamines during skin closure (P < 0.005), although duration of surgery, blood loss, and body temperature were not correlated. Early postoperative norepinephrine concentrations were correlated with pain score and duration of surgery (P < 0.004), but not with anesthetic management, blood loss, or body temperature. All postoperative norepinephrine levels were highly correlated (r = 0.7) with norepinephrine levels during skin closure. Cortisol excretion was higher postoperatively than intraoperatively. No patient or perioperative variable predicted cortisol excretion, and cortisol excretion was not correlated with catecholamine levels at any time. ConclusionsThese data Indicate that patient factors, such as age and Inherent sympathetic responsivity, are important determinants of the catecholamine response to surgery. Modulation of the norepinephrine response by regional anesthesia/analgesia appears to be related, in part, to superior analgesia. The lack of correlation between catecholamine and cortisol secretion indicates that the stress response may consist of discrete systems responding to different stimuli.

Catecholamine and cortisol responses to lower extremity revascularization: Correlation with outcome variables

OBJECTIVE To determine whether catecholamine and cortisol secretory responses to surgery contribute to postoperative complications. DESIGN Prospective, randomized, case series. SETTING A university hospital operating suite and surgical intensive care unit. PATIENTS Sixty patients undergoing lower extremity vascular surgery. INTERVENTIONS Patients were randomized to receive either epidural anesthesia/epidural opiate analgesia (regional anesthesia) or general anesthesia/intravenous patient-controlled analgesia (general anesthesia). MEASUREMENTS AND MAIN RESULTS Anesthesia was managed according to a prospectively designed protocol. Hemodynamic parameters and plasma catecholamine concentrations were determined at specific intraoperative and postoperative time points. Intraoperative and postoperative urine samples were collected and analyzed for free cortisol concentrations. Outcomes evaluated were cardiac (nonfatal myocardial infarction and cardiac death) and surgical (graft occlusion). Mean arterial pressure during emergence from anesthesia and in the early postoperative period correlated positively with plasma norepinephrine concentration (p < .01). In addition, plasma catecholamine concentrations were higher in patients with postoperative hypertension. Plasma norepinephrine concentrations at the time of emergence from anesthesia and postoperatively were also higher in patients requiring repeat surgery for graft revision, thrombectomy, or amputation (p < .05). Multivariate analysis indicated that the norepinephrine concentration at the time of emergence, but not type of anesthesia, correlated with reoperation for graft occlusion, suggesting that the previously reported beneficial effect of regional anesthesia may be due to modulation of the stress response. Myocardial infarction or cardiac death occurred in three patients. These patients had markedly increased catecholamine concentrations. CONCLUSIONS The catecholamine response to lower extremity vascular surgery contributes to the development of postoperative hypertension and may also be important in the development of thrombotic complications.

Right- and Left-arm Blood Pressure Discrepancies in Vascular Surgery Patients

To identify a relationship between atherosclerotic vascular disease and differences in blood pressure between the right and left arms, blood pressure differences between arms were measured in patients with peripheral vascular disease (PVD, n = 58), in patients with coronary artery disease (CAD, n = 38), and in patients with no evidence of atherosclerotic disease, who served as a control group (n = 38). The incidence and magnitude of right and left arm pressure difference determined by the oscillometric technique were compared between the patient groups. The incidence of systolic pressure difference greater than or equal to 20 mmHg between arms in patients with PVD (21%) was greater than that in either those with CAD (3%) (P less than or equal to 0.05) or control subjects (0%) (P less than 0.01). The incidence of systolic pressure difference greater than or equal to 45 mmHg between arms in patients with PVD (10%) was greater than that in either those with CAD (0%) (P less than 0.05) or control subjects (0%) (P less than 0.05). Patients with PVD also had a greater incidence of right and left arm difference than did those with CAD or controls for mean and diastolic blood pressures. Of all patients with a systolic difference greater than 10 mmHg, neither the right nor the left arm blood pressure was consistently higher: 21 of 35 (60%) had a higher pressure in the right arm, and 14 of 35 (40%) had a higher pressure in the left arm (P = 0.33). Gender, diabetes, hypertension, smoking, and age were not associated with a difference in blood pressure between the right and left arms.(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative rate-related silent myocardial ischemia and postoperative death

A case is presented that demonstrates heart rate (HR)--related silent myocardial ischemia occurring preoperatively, subsiding intraoperatively, then recurring and leading to a post-operative cardiac death in a patient undergoing peripheral vascular surgery. This case illustrates that patients may have an ischemic threshold for HR whereby recurrent depression of the ST segment may occur during increase of HR to rates as low as 80 to 85 beats per minute (bpm), even in the absence of acute blood pressure (BP) changes. Myocardial ischemia may be HR related; however, the authors are not aware of a case that demonstrates repeated episodes of rate-related ischemia occurring at HRs well below the 100 bpm traditional definition of tachycardia. The authors conclude that patients at risk for perioperative myocardial ischemia should be identified and the hemodynamic management of these patients should include control of HR. This implies control of the physiologic variables that influence HR, along with the use of beta-adrenergic blockers. This case also demonstrates the value of Holter monitoring for ischemia, which, when done preoperatively, can detect patients at risk for unfavorable cardiac outcomes. Ischemia monitoring also may be useful during the intraoperative and postoperative periods, a time when ischemia is often silent and undetected. The early recognition of ischemia would allow for anti-ischemic interventions, which could decrease the morbidity and mortality of patients at risk for perioperative cardiac complications.

Regional versus general anesthesia in high-risk surgical patients: The need for a clinical trial☆

Regional anesthesia is often preferred over general anesthesia for patients with cardiovascular disease because of presumed decreased risk of perioperative myocardial ischemia. However, few studies have addressed this issue directly. To determine whether the type of anesthesia is independently associated with myocardial ischemia, records of 134 patients undergoing peripheral vascular grafting under general or regional anesthesia were examined. There were no significant differences preoperatively between groups in ASA class, age, sex, or prevalence of angina, diabetes, or hypertension. Twelve patients developed myocardial ischemia or infarction within 7 days of operation; 11 of these 12 patients had received regional anesthesia (p less than 0.015). The association between anesthetic approach and perioperative myocardial ischemia or infarction remained after adjustment for preoperative factors associated with ischemia or with type of anesthesia. General anesthesia does not appear to be associated with increased risk of myocardial ischemia, and stringent recommendations to avoid it in this population may be unfounded. A clinical trial is needed to define more clearly the risks and benefits of different types of anesthesia in high-risk patients.