Tadikonda L. K. Rao

Reinfarction following anesthesia in patients with myocardial infarction.

The authors studied the incidence of and factors related to recurrent perioperative myocardial infarction retrospectively during 1973–1976 (Group 1) and prospectively during 1977–1982 (Group 2). Reinfarction occurred in 28 of 364 (7.7%) patients in Group 1 and 14 of 733 (1.9%) in Group 2 (P < 0.005). When the previous infarction was 0–3 and 4–6 months old, perioperative reinfarction occurred in 36% and 26% of Group 1 patients, respectively, and only 5.7% and 2.3% of Group 2 patients, respectively, (P < 0.05). In both groups, patients with associated congestive heart failure had a higher reinfarction rate. Patients who had intraoperative hypertension and tachycardia or hypotension develop had a higher incidence of reinfarction in both groups. The results suggest that preoperative optimization of the patients status, aggressive invasive monitoring of the hemodynamic status, and prompt treatment of any hemodynamic aberration may be associated with decreased perioperative morbidity and mortality in patients with previous myocardial infarction. Which of these factors, if any, contributed to the improved outcome was not determined in this study.

A review of pulmonary artery catheterization in 6,245 patients.

From July 1977 to December 1982, 6,245 patients requiring cardiac and noncardiac operations had pulmonary artery (PA) catheterizations for perioperative monitoring. Their ages ranged from 4 to 94 years. PA catheters were inserted through the external or internal jugular vein in 6,146 patients, while arm veins were used in 99 patients. Complications included persistent PVCs requiring therapy in 193 (3.1%), right bundle branch blocks in three (0.048%), left bundle branch and complete heart block each in one patient (0.016%), intrapulmonary hemorrhage in four (0.064%), minor pulmonary infarcts in four (0.064%), perforation of right ventricle in one (0.016%), and death from uncontrollable pulmonary hemorrhage in one patient (0.016%). This investigation reveals a low incidence of morbidity associated with PA catheterization.

Anticoagulation Following Placement of Epidural and Subarachnoid Catheters: An Evaluation of Neurologic Sequelae

&NA; The incidence of neurologic complications arising from anticoagulant therapy, following epidural and subarachnoid catheterization in 3,164 and 847 patients, respectively, was determined. Twenty patients experienced minor neurologic complications or low back pain which was self‐limiting and resolved with time. There was no incidence of peridural hematoma leading to spinal cord compression. This investigation shows that the occurrence of symptomatic hematomas following anticoagulation in patients with epidural or subarachnoid catheters is a very rare complication, assuming proper patient selection, an atraumatic technique, and appropriate monitoring of anticoagulant activity.

Intraoperative Detection of Patent Foramen Ovale by Transesophageal Echocardiography

This study reports the intraoperative use of contrast and Doppler echocardiography techniques to diagnose patent foramen ovale (PFO). Fifty patients without known atrial septal defects undergoing elective cardiovascular surgery were studied. A 5-MHz esophageal echocardiographic probe was used to image the fossa ovalis (FO) and 10 ml agitated saline was injected into the right atrium during apnea. Echocardiographic contrast was then injected during end-inspiration at 20-cmH2O airway pressure. When opacification of the right atrium was complete, the airway pressure was released. During these maneuvers, color and pulsed-wave Doppler interrogation of the atrial septum were also performed. Right-to-left passage of saline contrast across the interatrial septum was seen in 11 of 50 patients (22%). Doppler echocardiography demonstrated a PFO in 2 patients without contrast evidence of shunting. Thus, the combination of contrast and Doppler echocardiography identified a 26% (13 of 50) prevalence of PFO, approximating the previously reported autopsy rate of 25%. These contrast and Doppler techniques may be useful in detecting patients at risk for paradoxical emboli and in identifying candidates for closure of the PFO.

Angina and other risk factors in patients with cardiac diseases undergoing noncardiac operations.

Six hundred eighty-eight consecutive patients with cardiac diseases or who wer, ′older than 70 yr of age, all of whom were undergoing noncardiac operations, were studied. Twenty-four preopeiative risk factors were analyzed for the outcome of perioperative myocardial infarction (PMI) or cardiac death using stepwise logistic regression. Old age, emergency operation, angina, previous myocardial infarction, electrocardiographic signs of ischemia, type of surgical procedure, and hypokalemia were identified as individual factors useful in predicting outcome. Thirty-two patients (4.65%) developed PMI. Seven of these 32 patients (21.9%) and eight more patients without PMI—a total of 15 patients (2.2%)—died a cardiac death. Nonfatal but serious complications occurred in 23% of the patients. Patients undergoing emergency operations and patients with chronic stable angina, previous myocardial infarction, and electrocardio- graphic signs of ischemia were found to be at increased risk for PMI and cardiac death.

Hemodynamic response to changes in ventilatory patterns in patients with normal and poor left ventricular reserve.

Hemodynamic effects of controlled mechanical ventilation (CMV), intermittent mandatory ventilation (IMV), and intermittent mandatory ventilation with 5 cm H2O PEEP (IMV5PEEP) were studied in 20 patients after aortocoronary bypass surgery. Significant increases in cardiac index (CI) and stroke volume index (SI) (p < 0.01) resulted in patients with normal left ventricular end-diastolic pressure (LVEDP) and ejection fraction (EF) changing from CMV to IMV. With a change from IMV to IMVSPEEP, the CI and SI returned to CMV values. However, in patients with increased LVEDP with an EF of less than 0.6, suggesting poor ventricular function and reserve, when the mode of ventilation was changed from CMV to IMV, right atrial pressure (RAP) and pulmonary artery occlusion pressure (PAOP) significantly increased (p < 0.01) with an associated significant decrease in mean arterial pressure (MAP), CI, SI (p < 0.01). When these patients were placed on IMV5PEEP, the hemodynamic variables returned to the values obtained during CMV. We conclude that changing from CMV to IMV has salutory effects on the patients hemodynamic values with normal left ventricular function. But in patients with failing left ventricle, volume overload of right ventricle which occurs with the institution of spontaneous respiration during IMV has deleterious effects on the hemodynamic variables. These deleterious effects can be effectively negated by the application of IMV5 PEEP.

Transesophageal echocardiographic demonstration of distinct mechanisms for right to left shunting across a patent foramen ovale in the absence of pulmonary hypertension

The optimal visualization of the atrial septum and fossa ovalis by transesophageal echocardiography was utilized to demonstrate saline contrast transit across the atrial septum and to relate it to the motion of the flap valve (septum primum) of the fossa ovalis. In three cases, three distinct mechanisms of right to left interatrial shunting in the absence of right ventricular systolic hypertension were identified: 1) transient spontaneous reversal of the left to right atrial pressure differential with each cardiac cycle; 2) sustained elevation of right atrial pressure above left atrial pressure induced by respiratory maneuvers; and 3) aberrant flow redirection across the foramen ovale due to a large right atrial mass. Any of these three mechanisms may be operative during paradoxic embolism in the absence of elevation of right ventricular pressures.

Reevaluation of perioperative myocardial infarction in patients with prior myocardial infarction undergoing noncardiac operations

We studied 275 patients with prior myocardial infarctions undergoing noncardiac operations to determine the incidence and outcome of perioperative myocardial reinfarction. Perioperative myocardial reinfarction developed in 13 patients (4.7%) of whom 3 (23%) died of cardiac causes. When time between prior myocardial infarction and the date of anesthesia was analyzed, the incidence of perioperative myocardial reinfarction was 4.3% at 0–3 mo, 0 at 4–6 mo, 5.7% at >6 mo, and 3.3% at an indeterminate exact interval. None of the variables analyzed showed any significant correlation with the rate of reinfarction. The urgency of operation and aortic or vascular procedures were the only variables that approached, but failed to achieve, statistical significance.

Convulsions: An Unusual Response to Intravenous Fentanyl Administration

Intravenous fentanyl in doses of 100 to 150 pg/kg are today being used in cardiac anesthesia (1). The popularity of this technique has been due in part to stability of the cardiovascular system during induction of anesthesia and to suppression of stress responses to surgery (2, 3). The few complications associated with fentanyl-oxygen anesthesia include chest rigidity during induction of anesthesia (4,s) a n d awareness and recall of the intraoperative events (6) in the postoperative period. Recently we encountered five cases of generalized seizures during the rapid intravenous administration of fentanyl and we report two of these cases.

Ventilator-induced barotrauma in controlled mechanical ventilation versus intermittent mandatory ventilation.

: Retrospective analysis of pulmonary barotrauma incidence in 292 patients ventilated greater than or equal to 24 h was conducted. From 1971-1973, 156 patients with acute respiratory insufficiency were managed with controlled mechanical ventilation (CMV) and PEEP. During 1973-1976, 136 patients were supported with IMV and CPAP. Despite higher mean peak and end-expiratory airway pressure, the IMV-CPAP group exhibited a significantly lower incidence of ventilator-induced barotrauma; 7% vs 22% (p less than 0.01). We suspect the difference is related to fewer mechanical breaths with IMV and not to the level of end-expiratory pressure employed.