Anesthesia and Pulmonary Hypertension

Abstract

Anesthesia and surgery are associated with significantly increased morbidity and mortality in patients with pulmonary hypertension due mainly to right ventricular failure, arrhythmias, postoperative hypoxemia, and myocardial ischemia. Preoperative risk assessment and successful management of patients with pulmonary hypertension undergoing cardiac surgery involve an understanding of the pathophysiology of the disease, screening of patients at-risk for pulmonary arterial hypertension, analysis of preoperative and operative risk factors, thorough multidisciplinary planning, careful intraoperative management, and early recognition and treatment of postoperative complications. This article will cover each of these aspects with particular focus on the anesthetic approach for non-cardiothoracic surgeries.

Introduction

Advances in the understanding of the pathogenesis and pathophysiology of pulmonary hypertension (PH) and the availability of new drug therapies for pulmonary arterial hypertension (PAH) have led to improved survival and increased awareness of this life-threatening condition. It has been known for many years that non-cardiac surgery, particularly Cesarean section for parturient woman with Eisenmenger's Syndrome (ES), has been associated with high mortality of up to 70%.1, 2, 3 PH is also well known to complicate heart disease, and morbidity and mortality with cardiac surgery in such patients are increased.4, 5, 6, 7, 8, 9 Conversely, data regarding the risk factors and outcomes of PH patients undergoing non-cardiac surgery have been scarce, probably because PH may have been occult or overlooked pre-operatively, whereas the presence of PH before cardiac surgeries is often identified with routine pre-operative testing. Data are now mounting about the risks of anesthesia and surgery in patients with PH, and this article will focus on the peri-operative management of patients with PH undergoing non-cardiac surgery.

To date, there have been five retrospective studies reporting outcomes following non-cardiac surgery in patients with PH. Each of the studies varied in the diagnostic methods and definitions of PH used, the causes and severity of PH, and whether or not a control population was included.10, 11, 12, 13, 14 Perioperative morbidity occurred in 15%–42% of patients, and included post-operative respiratory failure (7%–28%),10, 13 heart failure (10%–13.5%),10, 11, 13 hemodynamic instability (8%),¹⁰ dysrhythmias (12%),¹³ renal insufficiency (7%),¹³ sepsis (7%–10%),10, 13 ischemia/myocardial infarction (4%), delayed tracheal extubation (8%–21%),10, 11 longer ICU¹⁰ and total hospital length of stays,¹⁰ and a trend towards greater 30 day readmissions (16.7% and 7.8% in PH vs non-PH patients, respectively; p = 0.08, OR 2.4).¹⁰ In-hospital mortality was as low as 1%¹⁰ in a study that included mostly patients with PH related to left heart failure, however mortality rates in the remaining four studies were between 7% and 10%.11, 12, 13, 14 Interestingly, perioperative mortality with non-cardiac surgery was the same (7%) in a study that included only patients with mild–moderate pre-capillary PH¹² as it was in another study of patients with severe PAH (Eisenmenger's syndrome),¹⁴ however both studies were small. It now seems clear that patients with PH of any etiology and severity, not just the rare disease PAH, have increased risk of perioperative morbidity and mortality with both cardiac and non-cardiac surgeries. Importantly, however, is that the perioperative management of patients with PH varies drastically, depending upon the etiology and severity of the disease.

Successful management of the perioperative patient with PH is complex and requires a thorough understanding of the pathophysiology of PH and right ventricular (RV) function along with multiple steps that need to be taken, including recognition of the disorder, especially in patients at-risk for developing PAH (e.g. connective tissue disease, portal hypertension, congenital heart disease, and HIV infection), identification of the underlying cause(s), assessment of the severity of disease, assessment of the risks versus benefits of anesthesia and surgery, development of an anesthetic plan, and vigilant monitoring in the critical care setting for the early recognition and treatment of any post-operative complications.