Anesthetic management of emergency laparotomy in a case of ischemic cardiomyopathy with COPD.

Anesthesia for non-cardiac surgeries in patients with ischemic cardiomyopathy with other co-morbidities is a challenging situation for anesthetists. The choice of anesthesia and anesthetic agents should be judicious and balanced to maintain optimum cardiac output and to avoid myocardial depression for a successful postoperative outcome. Here, we describe the anesthetic management for emergency exploratory laparotomy in a patient who was suffering from ischemic cardiomyopathy along with chronic obstructive pulmonary disease and was presented to the emergency operation theater for gastrointestinal tract perforation.

INTRODUCTION

Ischemic cardiomyopathy (ICM) is a common cause of heart failure among middle-aged and elderly people. Although ICM is no longer considered to be a type of dilated cardiomyopathy (DCM),[1] the presentation of this disease, however, highly mimics the clinical picture of DCM. Incidence of high morbidity and mortality[23] mandates intensive management with special attention toward cardiovascular status in these patients, more so when the cardiomyopathy is associated with other co-morbidities and in emergency set-up where cardiovascular instability is the rule. We describe a balanced and successful anesthetic management plan for emergency laparotomy in a case of ICM with chronic obstructive pulmonary disease (COPD) as co-existing disease using limited anesthetic resources which are commonly available in developing countries.

CASE REPORT

A 55-year-old male was brought to the emergency department for acute pain abdomen, localized to left hypochondrium and umbilical area for 24 h, with non-passage of flatus and distension of abdomen for 12 h. He was diagnosed with ICM 6 years back, for which he had been receiving aspirin, ramipril, digoxin, and atorvastatin. He was also suffering from COPD for last 8 years and was on regular inhalers with salbutamol and budesonide.

As per the history, clinical examination and radiological findings, he was provisionally diagnosed with gastrointestinal tract perforation probably of gastric origin, and shifted to the emergency operation theater for immediate exploratory laparotomy. Preoperative cardiovascular system examination revealed muffled first heart sound but normal second heart sound without any signs of heart failure or arrhythmia. There was mild hypotension (92/58 mmHg) with tachycardia (128/min). Respiratory system examination revealed bilateral coarse crepitations at basal region and tachypnea (31/min) with labored breathing. Preoperative arterial blood gas (ABG) analysis revealed mild metabolic acidosis [Table 1]. Routine blood investigations and pancreatic enzymes profile were within normal limits. His electrocardiogram (ECG) revealed ST segment depression and T wave inversion in chest leads. Chest X-ray revealed presence of cardiomegaly. His echocardiography revealed ischemic DCM with regional wall motion abnormality and poor left ventricular function [Table 2].

Table 1

Preoperative arterial blood gas analysis report

Table 2

Some important echocardiography features

In the operation theater, he was given oxygen by face mask throughout the preoperative period and was nebulized by salbutamol solution. Monitoring was done with continuous ECG, pulse oximetry, heart rate, central venous pressure (CVP) and invasive blood pressure. Intravenous fluids (0.9% saline) were administered according to the CVP and urine output. Premedication was done with ondansetron (100 μg/kg), fentanyl (4 μg/kg), and midazolam (3 mg). Dobutamine infusion was started to keep the mean blood pressure above 60 mmHg. Induction was done with ketamine 50 mg and slow injection of propofol in a titrated way to a total of 50 mg. Intubation was done following succinylcholine (1 mg/kg) administration and Sellick's maneuver application. Lidocaine was used to obtund intubation response. Anesthesia was maintained with oxygen and nitrous oxide at 1:1 ratio, two separate continuous infusions of propofol (25–75 μg/kg/min) and fentanyl (1 μg/kg/min), and intermittent dose of vecuronium. The propofol and dobutamine infusions were adjusted according to the cardiovascular response.

A jejunal stricture with a perforation proximal to it was found. A resection and anastomosis was done. Postoperatively, the patient was shifted to intensive care unit with the tracheal tube in situ for elective ventilation. The immediate postoperative ABG analysis revealed mild metabolic acidosis, but did not require correction. Postoperative sedation and analgesia was maintained with fentanyl and propofol infusion. He was extubated 12 h postoperatively. The dobutamine infusion was continued till postoperative day 2. On postoperative day 3, he was shifted to surgical ward after stabilization of the cardiovascular status without any inotropic support.

DISCUSSION

ICM, which produces clinical picture that is often indistinguishable from DCM with or without preceding history of angina or myocardial infarction (MI), develops as DCM with depressed ventricular function not explained by the extent of coronary artery obstructions or ischemic damage.[4] ICM is associated with worse prognosis than other non-ischemic types of DCM, probably because of the added risk of ischemic events to the existing DCM.[5] It often follows anterior wall MI and to a smaller extent inferior wall MI, which produces left ventricle remodeling with a drop in ejection fraction. Congestive heart failure, particularly left sided, along with fatigue and weakness are the major symptoms. Features of both supraventricular and ventricular arrhythmias and systemic or pulmonary emboli are also common in ICM. Treatment of ICM is similar to that of DCM.[6]

The goals for anesthetic management are similar to those of DCM, with an emphasis on prevention of ischemic events, and consists of avoidance of drug-induced myocardial depression, maintenance of normovolemia, prevention of increased ventricular after load, and avoidance of tachycardia with maintenance of sinus rhythm. Hypotension, however, must be prevented by using vasopressor to avoid myocardial hypoperfusion and ischemia. Here, in this patient, COPD acted as additional concern during anesthetic management. A pulmonary function test (PFT) was not advised in our patient as the general condition of the patient needed an immediate exploratory laparotomy, and also, the preoperative PFT does not identify patients in whom the surgery should be postponed or cancelled.[7] We, however, optimized the patient preoperatively by nebulization with salbutamol before intubation. Pulmonary artery catheterization and transesophageal echocardiography are the best choice for guiding fluid therapy and for pharmacological management in this group of patients.[8] However, this may not be feasible in emergency operations as they are technically demanding and time-consuming procedures. We used central venous catheter to guide fluid therapy according to the CVP, instead of pulmonary artery catheter due to its unavailability in our place. Monitoring direct arterial blood pressure is an important tool to identify abrupt hemodynamic changes. The responses of sedative drugs or induction agents may be slow due to the slow circulation time. Therefore, administration of these agents on the basis of clinical response may lead to overdosage. Preoperative assessment of serum electrolytes followed by perioperative correction of any significant electrolyte abnormalities, if present, should be made as these patients frequently suffer from drug-induced electrolyte abnormality. As these patients are prone to life-threatening ventricular arrhythmias, antiarrhythmic drugs such as lidocaine, amiodarone, or defibrillator should be kept ready at hand to treat arrhythmia. Inotropic support by dobutamine, dopamine, or phosphodiesterase inhibitors should be given if required during perioperative period.

Drugs like ketamine, etomidate, and narcotics have minimal depressing effect on cardiac function and are used frequently. Ketamine has been successfully used for induction of anesthesia in patients with DCM, alone or with other agents, viz. fentanyl and midazolam.[9] Conventional anesthetics like propofol, thiopentone sodium, or isoflurane in recommended doses depress cardiac function.[10] We used ketamine and propofol for induction to get stable hemodynamics. Use of ketamine decreased the amount of propofol needed for induction, and thus avoided further cardiac depression. Maintenance of anesthesia can be done either by using inhalational anesthesia or with total intravenous anesthesia (TIVA). We used nitrous oxide (50%) supplemented by low-dose propofol infusion and fentanyl infusion and spared the use of isoflurane for maintenance of anesthesia. Etomidate as induction agent and xenon for maintenance of anesthesia are probably the most ideal for general anesthesia technique.[11] However, cost and availability of xenon prevent its routine use in developing countries. Skeletal muscle paralysis is provided by non-depolarizing muscle relaxants such as vecuronium that lack significant cardiovascular effects.

CONCLUSION

For successful anesthesia, the anesthesia plan for these patients should include optimization of the cardiac status, avoidance of myocardial depressants, and a balanced anesthesia technique.