PULMONARY HYPERTENSION

doi:10.1016/S0889-8537(05)70125-5

Anesthesiology Clinics of North America

Volume 17, Issue 3, 1 September 1999, Pages 693-707

https://doi.org/10.1016/S0889-8537(05)70125-5 Get rights and content

Pulmonary hypertension has a diverse origin and can develop as a consequence of numerous systemic, cardiac, or pulmonary conditions or can result from disorders primarily affecting the pulmonary vascular bed. The hallmark of pulmonary hypertension is an elevation in pulmonary vascular resistance (PVR) that is primarily localized to the precapillary muscular arteries and arterioles.⁵⁰ The elevation in vascular resistance may be anatomic or vasoconstrictive in origin. Mechanisms from both components, particularly in vascular disorders of long standing, have contributions from both mechanisms.²³ The progressive reduction in cross-sectional area of distensibility of the pulmonary vascular bed results in a compromised pulmonary circulation. Increase in blood flow (cardiac output [CO]), such as exercise or stress, results in elevations in pulmonary artery pressure.⁴⁵ As the disease progresses, smaller increases in blood flow are required to elevate the pulmonary artery pressure. Eventually, the process may be so severe that even resting CO results in an elevated pulmonary artery pressure. The elevated pulmonary artery pressure results in a dysfunctional right ventricle, which initially accommodates the increase in afterload by dilation and hypertrophy but eventually fails because of disease progression. Pulmonary hypertension is a serious disease associated with a high mortality during surgery and anesthesia.10, 32, 34, 59 Therapeutic options with emphasis on the value of preoperative pulmonary vasodilator testing are reviewed.

Section snippets

DEFINITION

Pulmonary hypertension comprises a family of disorders occurring as a primary disease or as a complication of numerous systemic, cardiac, or pulmonary conditions. The normal pulmonary artery pressure at sea level ranges from a peak systolic volume of 18 to 25 mm Hg and a mean value ranging from 12 to 16 mm Hg. Pulmonary hypertension is defined as a resting pulmonary artery systolic or mean pressure exceeding 30 mm Hg or 20 mm Hg, respectively.

PATHOPHYSIOLOGY

The pulmonary circulation must be able to provide blood flow that is matched to the air supply. The normal pulmonary circulation is a low pressure system with remarkably low resistance that can accommodate large increases in blood flow with only slight increases in pulmonary artery pressure. A fourfold increase in blood flow (CO) during exercise is accompanied by a doubling of mean pulmonary artery pressure through recruitment and dilation of vessels.⁵³ The increase in pulmonary capillary wedge

RESPONSE TO FACTORS

The pulmonary circulation is particularly sensitive to reduction in alveolar oxygen tension, and it appears that the resulting pulmonary vasoconstriction is important as a local compensatory mechanism to regional ventilation/perfusion imbalances.⁴⁶ The response to hypoxia appears to be both age and species dependent. Young people appear to have an exaggerated response that diminishes with aging. The global response to alveolar hypoxia and resulting increase in PVR can be demonstrated in

PRIMARY PULMONARY HYPERTENSION

Primary pulmonary hypertension (PPH) is a condition defined by sustained elevation of pulmonary artery pressure without a demonstrable cause. The incidence ranges between 1 to 2 cases per 1 million people in the general population.⁶³ A similar clinical picture can occur in patients with portal hypertension,²⁰ human immunodeficiency virus (HIV) infection,⁴⁹ or a history of cocaine inhalation,⁶⁵ and in those taking appetite suppressant medications.¹

Familial PPH is inherited as an autosomal

DIAGNOSIS

The diagnosis of PPH is complicated by the nonspecific nature of the symptoms and subtlety of the signs of less advanced disease. The mean interval from the onset of symptoms to diagnosis is about 2 years in PPH.⁵⁶ In about 10% of patients, however, the diagnosis is delayed until after 3 years of symptoms.⁵⁶ The most common presenting symptom for seeking medical advice is the development of dyspnea. The median period of survival after diagnosis, as reported in the National Institutes of Health

SECONDARY PULMONARY HYPERTENSION

The incidence of secondary pulmonary hypertension is far more common than that of PPH and results from an identifiable cause. A classification based on hemodynamic causes is given in Table 1. Cardiac disorders produce pulmonary hypertension by increasing the resistance to pulmonary venous drainage or pulmonary blood flow. The increased resistance to pulmonary venous drainage may arise from various disorders but is most commonly seen in patients exhibiting left-sided valvular disorders (aortic

Nitric Oxide

The discovery of endogenous nitric oxide production evolved from studies of the role of the endothelium in modulating vascular tone. Furchgott and Zawadzki²⁵ observed that vascular rings relaxed only if the endothelium was intact. The vasodilator effects were the result of an endothelium substance (EDRF) that diffused into the smooth muscle and caused smooth muscle relaxation. In 1987, two groups independently showed that EDRF and nitric oxide were the same substance.31, 46 Nitric oxide is a

ANESTHESIA MANAGEMENT

The anesthetic management of patients with pulmonary hypertension presents a clinical challenge because the normal physiologic changes that accompany anesthesia and surgery can result in acute increases in PVR, leading to right ventricular failure. The increased morbidity and mortality with anesthesia and surgery have been well documented.9, 15, 42 Maternal mortality in Eisenmenger's syndrome and PPH exceeds 50%.⁷⁶ The risks associated with PPH are more frequent than those related to secondary

SUMMARY

Considerable progress has been made in the treatment and anesthetic management of patients with pulmonary hypertension. Preoperative pulmonary vasodilator testing can provide an estimation of risk and provide therapeutic options in the perioperative period. Further advances in understanding of the pathologic process as well as new pharmacologic options will further improve the anesthesiologist's approach to this difficult group of disorders.

References (76)

I. Adatia et al.
Inhaled nitric oxide and hemodynamic evaluation of patients with pulmonary hypertension before transplantation
J Am Coll Cardiol
(1995)
A. Costard-Jackle et al.
Influence of preoperative pulmonary artery pressure on mortality after heart transplantation: Testing of potential reversibility of pulmonary hypertension with nitroprusside is useful in defining a high risk group
J Am Coll Cardiol
(1992)
B.S. Edwards et al.
Coexistent pulmonary and portal hypertension: Morphologic and clinical features
J Am Coll Cardiol
(1987)
P. Ewalenko et al.
Comparison of the effects of isoflurane with those of propofol on pulmonary vascular impedance in experimental embolic pulmonary hypertension
Br J Anaesth
(1997)
T. Haneda et al.
Effects of oxygen breathing on pulmonary vascular input impedance in patients with pulmonary hypertension
Chest
(1983)
A. Inoue et al.
The human preproendothelin-1 gene: Complete nucleotide sequence and regulation of expression
J Biol Chem
(1989)
M. Packer et al.
Adverse hemodynamic and clinical effects of calcium channel blockade in pulmonary hypertension secondary to obliterative pulmonary vascular disease
J Am Coll Cardiol
(1984)
J. Pepke-Zaba et al.
Inhaled nitric oxide as a cause of selective pulmonary vasodilatation in pulmonary hypertension
Lancet
(1991)
B.A. Prins et al.
Prostaglandin E2 and prostacyclin inhibit the production and secretion of endothelin from cultured endothelial cells
J Biol Chem
(1994)
S. Rich et al.
Magnitude and implications of spontaneous hemodynamic variability in primary pulmonary hypertension
Am J Cardiol
(1985)

L.J. Rubin

Primary pulmonary hypertension

Chest

(1993)

P.H. Schaiberger et al.