Our data demonstrate that children with PAH have a significant risk of major perioperative cardiovascular complications, including cardiac arrest, pulmonary hypertensive crisis, and death, when undergoing sedation or anesthesia for cardiac catheterization procedures. Overall complications were more frequent in children with systemic or suprasystemic PAH, but were not associated with patient age, etiology of PAH, type of anesthetic, or airway management techniques.
The incidence of perioperative cardiac arrest that we found to be associated with PAH is much greater than published incidences of perioperative cardiac arrest in all children. The initial findings of the Pediatric Perioperative Cardiac Arrest (POCA) Registry report an overall incidence of perioperative cardiac arrest of 0.0265%, an incidence of anesthesia-related cardiac arrest of 0.014%, and an incidence of anesthesia-related death of 0.0036% (6
). The overall incidences of perioperative cardiac arrest and death in a pediatric teaching hospital without open cardiac or neurosurgical services were reported to be 0.033% and 0.004%, respectively (7
). Our institution’s unpublished overall incidence of perioperative cardiac arrest from 2001 through 2004 was 0.024% (Quality Assurance Program, Department of Anesthesiology, The Children’s Hospital, Denver). In comparison, the three cardiac arrests that occurred during our 256 procedures in children with PAH represent an incidence of 1.17%, and the two deaths 0.78%.
Major complications are more frequent in association with pediatric cardiac catheterization. A leading pediatric cardiac center reported the incidences of perianesthetic cardiac arrest and death associated with cardiac catheterization to be 0.49% and 0.08%, respectively (5
). Our institution’s incidence of intraoperative cardiac arrest and perioperative death associated with cardiac catheterization (excluding PAH patients) from 2000 through 2004 was 0.07% and 0.11%, respectively (Quality Assurance Program, Division of Cardiology, The Children’s Hospital, Denver). In comparison, the three cardiac arrests that occurred during our 141 catheterization procedures in children with PAH represent an incidence of 2.1%, and the two deaths 1.4%.
There is not a significant body of literature about PAH and its associated complications in children who require anesthesia care. Studies of adults demonstrate that the presence of PAH significantly contributes to adverse outcomes after both cardiac and noncardiac surgery (8
). Reich et al. (8
), in a retrospective analysis of computerized intraoperative databases, determined that pulmonary hypertension was a predictor of perioperative myocardial infarction and death in a large cohort of adult patients undergoing coronary artery bypass grafting. Ramakrishna et al. (9
) performed a retrospective analysis of adult patients with PAH who had undergone noncardiac surgery and reported a high incidence of early postoperative morbidity and a mortality rate of 7%, indicating the serious impact of PAH. In a retrospective study of 276 pediatric and adult patients with congenital heart disease undergoing noncardiac surgery, Warner et al. (10
) found that PAH, cyanosis, congestive heart failure, and age <2 yr was a predictor of perioperative morbidity.
Studies of adults with PAH have reported other perioperative factors that have varying importance in predicting morbidity. Long duration of anesthesia was a significant independent predictor of morbidity in adults with PAH (9
). Although long duration of the procedure achieved significance in our univariate analysis, it did not prove to be an independent predictor of major complications when subjected to multivariate logistic regression (long duration was due to the time taken to resuscitate and/or stabilize children with PAH crises before transfer to the pediatric intensive care unit). Similar to the findings of Warner et al. (10
), our data suggest that general anesthesia versus nongeneral anesthesia is not a significant factor associated with complications.
Compared to the published studies of PAH in adults, ours is limited by a relatively small number of subjects; thus, our ability to identify a significant association between some variables and complications may have been limited by inadequate power, or a Type II statistical error. A further limitation of retrospective studies is that details of clinical management and other data can be incomplete or lacking; thus, some complications or other important information can be missed. We anticipate that both outcomes and contributing factors such as anesthetic management and surgical techniques will be more precisely defined as experience grows.
Several mechanisms can be associated with hemodynamic deterioration in patients with PAH. Of critical importance among these mechanisms is a rapid increase in PVR related to pulmonary arterial vasoreactivity. Hypercarbia, hypoxia, acidosis, and noxious stimuli such as pain and airway instrumentation can trigger a rapid increase in PVR (1
) that can lead to a pulmonary hypertensive crisis and/or right heart failure. It was not apparent during this retrospective review that hypercarbia, acidosis, pain, or airway instrumentation contributed to any complications; SpO2
, and arterial blood gases were generally well documented. However, one pulmonary hypertensive crisis that responded quickly to iNO appeared to be associated with exposure to subambient FiO2
during evaluation of pulmonary vasoreactivity. Unrecorded noxious stimuli, including catheter stimulation of the heart or pulmonary vasculature, could have contributed.
Anesthesiologists should be aware that other mechanisms can also contribute to right-sided heart failure in patients with PAH. Hypovolemia can provide inadequate preload to the right ventricle, leading to decreased stroke volume, cardiac output, and pulmonary blood flow. Systemic hypotension or a decrease in systemic vascular resistance can cause a decrease in coronary artery blood flow, leading to biventricular ischemia. Compensatory right ventricular hypertrophy or dilation can compress the septal wall of the left ventricle, leading to inadequate filling of the left ventricle, decreased stroke volume, and decreased cardiac output. Hypoxemia related to problems with ventilation, lung disease, or decreased pulmonary blood flow can further impair ventricular function.
The hemodynamic and pulmonary vascular effects of anesthetic drugs have been reviewed elsewhere (2
) and should be considered in the anesthetic care of children with PAH. Sedation without general anesthesia is a common technique for cardiac catheterization of selected patients and was used in 56 of the 141 cardiac catheterization procedures in this series. Fentanyl and midazolam were the most commonly used combination and are thought to have little direct effect on the pulmonary vasculature. Oversedation does occur during procedural sedation, however (21
), and can be associated with hypercarbia, hypoxemia, and airway obstruction in patients managed with a natural airway and spontaneous ventilation (22
). These clinical problems can also occur during general anesthesia and must be avoided in patients with PAH.
Selective pulmonary vasodilators are frequently used perioperatively, even in the absence of hemodynamic deterioration. During cardiac catheterization procedures for evaluation of PAH, iNO is administered to test pulmonary vasoreactivity. For other surgical procedures, iNO is usually administered prophylactically intraoperatively and continued postoperatively via nasal cannulae (23
). Postoperative withdrawal of iNO or other pulmonary vasodilators can be associated with life-threatening rebound pulmonary hypertension; this must be anticipated and can be attenuated by administration of other pulmonary vasodilators (24
). Treatment of pulmonary hypertensive episodes involves 100% oxygen, hyperventilation, attenuation of noxious stimuli, and pharmacologic pulmonary vasodilators. Such treatment and drugs have been reviewed elsewhere (1
In summary, our data indicate that children with suprasystemic PAH have a perioperative risk of major complications, including cardiac arrest, pulmonary hypertensive crisis, and death that is many times greater than that reported for the general pediatric population. It is important that anesthesiologists be aware of this increased risk, understand the pathophysiology of PAH, form an appropriate anesthetic management plan, and be prepared to treat cardiovascular deterioration.