Thoracic epidural anaesthesia and primary pulmonary hypertension

Our current understanding of and approach to the management of lung cancer with pulmonary hypertension

INTRODUCTION

Lung cancer is a frequent pathology for which the best curative treatment is pulmonary resection. Pulmonary arterial hypertension is a rare disease but pulmonary hypertension associated with parenchymal disease or left heart disease is frequently observed in these patients. The diagnosis of pulmonary hypertension before lung resection makes the perioperative management of these patients more difficult and sometimes leads to rejecting patients for surgery.

AREAS COVERED

We performed a review of literature on PubMed on Pulmonary hypertension associated lung resection, preoperative assessment of lung resection and perioperative management of PH patients, including guidelines and clinical trials.In this review, we summarize the current state of knowledge regarding the pre and perioperative management of patients with suspected or confirmed PH who can benefit from surgical treatment of lung cancer.

EXPERT OPINION

Management of PH patients before lung resection should include a very careful workup including at least right heart catheterization with evaluation of the targeted PH treatment in an expert center and evaluation of other comorbidities. Perioperative management must be carried out in a specialized center.

Spectrum of postoperative complications in pulmonary hypertension and obesity hypoventilation syndrome

PURPOSE OF REVIEW

The purpose of this review is to identify chronic pulmonary conditions which may often not be recognized preoperatively especially before elective noncardiac surgery and which carry the highest risk of perioperative morbidity and mortality.

RECENT FINDINGS

This review discusses some of the most recent studies that highlight the perioperative complications, and their prevention and management strategies.

SUMMARY

Pulmonary hypertension is a well recognized risk factor for postoperative complications after cardiac surgery but the literature surrounding noncardiac surgery is sparse. Pulmonary hypertension was only recently classified as an independent risk factor for postoperative complications in the American Heart Association/American College of Cardiology Foundation Practice Guideline for noncardiac surgery. Spinal anesthesia should be avoided in most surgeries on patients with pulmonary hypertension because of it's rapid sympatholytic effects. The presence of significant right ventricle dysfunction and marked hypoxemia should prompt re-evaluation of the need for elective surgery. Obesity hypoventilation syndrome is even harder to recognize preoperatively as arterial blood gases are generally not obtained prior to elective noncardiac surgery. Amongst patients with obstructive sleep apnea this group of patients carries much higher risk of postoperative respiratory and congestive heart failure.

Aspects of Anesthesia for Lung Transplantation

Anesthesia for lung transplantation is both a demand ing and rewarding experience. Success requires team- work, experience, knowledge of cardiorespiratory patho physiology and its anesthetic implications, appropriate use of noninvasive and invasive monitoring, and the ability to respond quickly and effectively to life- threatening perioperative events. Specific issues in clude management of a patient with end-stage lung and heart disease, lung isolation and one-lung ventilation, perioperative respiratory failure, pulmonary hyperten sion, and acute right ventricular failure. Recent ad vances include greater understanding of dynamic hyper inflation ("gas-trapping") during mechanical ventilation, perioperative use of inhaled nitric oxide and treatment of acute right ventricular failure. Successful anesthetic management leads to greater hemodynamic stability, improvement in gas exchange and a reduction in need for cardiopulmonary bypass, all of which should lead to improved patient outcome.

Management of Pulmonary Hypertension in the Operating Room

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.

Association of thoracic epidural analgesia with risk of atrial arrhythmias after pulmonary resection: a retrospective cohort study

PURPOSE

Atrial arrhythmias are common after non-cardiac thoracic surgery. We tested the hypothesis that TEA reduces the risk of new-onset atrial arrhythmias after pulmonary resection.

METHODS

We evaluated patients who had pulmonary resection. New-onset atrial arrhythmias detected before hospital discharge was our primary outcome. Secondary outcomes included other cardiovascular complications, pulmonary complications, time-weighted average pain score over 72 h, and duration of hospitalization. Patients with combination of general anesthesia and TEA were matched on propensity scores with patients given general anesthesia only. The matched groups were compared by use of logistic regression, linear regression, or Cox proportional hazards regression, as appropriate.

RESULTS

Among 1,236 patients who had pulmonary resections, 937 received a combination of general anesthesia and TEA (TEA) and 299 received general anesthesia only (non-TEA). We successfully matched 311 TEA patients with 132 non-TEA patients. We did not find a significant association between TEA and postoperative atrial arrhythmia (odds ratio (95 % CI) of 1.05 (0.50, 2.19), P = 0.9). TEA was not significantly associated with length of hospital stay or postoperative pulmonary complications (odds ratio (95 % CI) of 0.71 (0.22, 2.29), P = 0.47). TEA patients experienced fewer postoperative cardiovascular complications; although the association was not statistically significant (odds ratio (95 % CI) of 0.30 (0.06, 1.45), P = 0.06). Time-weighted average pain scores were similar in the two groups.

CONCLUSION

TEA was not associated with reduced occurrence of postoperative atrial arrhythmia. Although postoperative pulmonary complications were similar with and without TEA, TEA patients tended to experience fewer cardiovascular complications.

Pulmonary hypertension: an important predictor of outcomes in patients undergoing non-cardiac surgery

OBJECTIVES

Perioperative risk associated with pulmonary hypertension (PH) in patients undergoing non-cardiac surgery (NCS) remains poorly defined. We report perioperative outcomes in a large cohort of patients undergoing NCS, comparing those with and without PH.

METHODS

Patients undergoing NCS at our institution between January 2002 and December 2006, were cross matched with a Right Heart Catheterization (RHC) database for the same period. Patients were excluded if they were <18 years old and if they underwent cardiac surgery prior to NCS or minor procedures using local anesthesia or sedation. Controls were defined as patients who underwent similar NCS with mean pulmonary arterial pressure (MPAP) ≤ 25 mmHg.

RESULTS

173 patients underwent RHC and NCS during the specified period and were included in the analysis. Of these 96 (55%) had PH. Mean pulmonary arterial pressure (p = 0.001), American Association of Anesthesiology Class (p = 0.02), and chronic renal insufficiency (p = 0.03) were determined as independent risk factors for post-operative morbidity. Patients with PH were more likely to develop congestive heart failure (p < 0.001; OR: 11.9), hemodynamic instability (p < 0.002), sepsis (p < 0.0005), and respiratory failure (p < 0.004). Patients with PH needed longer ventilatory support (p < 0.002), stayed longer in the ICU (p < 0.04), and were more frequently readmitted to the hospital within 30 days (p < 008; OR 2.4).

CONCLUSIONS

In addition to the traditionally known risk factors for outcomes after NCS such as coronary artery disease, diabetes mellitus, chronic renal insufficiency, American Society of Anesthesiology class, the presence of underlying PH can have a significant negative impact on perioperative outcomes.

Anesthetic management of children with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications, including pulmonary hypertensive crisis and cardiac arrest. Several mechanisms of hemodynamic deterioration, including acute increases in pulmonary vascular resistance (PVR), alterations of ventricular contractility and function and coronary hypoperfusion can contribute to morbidity. Anesthetic drugs exert a variety of effects on PVR, some of which are beneficial and some undesirable. The goals of balanced and cautious anesthetic management are to provide adequate anesthesia and analgesia for the surgical procedure while minimizing increases in PVR and depression of myocardial function. The development of specific pulmonary vasodilators has led to significant advances in medical therapy of PAH that can be incorporated in anesthetic management. It is important that anesthesiologists caring for children with PAH be aware of the increased risk, understand the pathophysiology of PAH, form an appropriate anesthetic management plan and be prepared to treat a pulmonary hypertensive crisis.

Therapeutic administration of thoracic epidural anesthesia reduces cardiopulmonary deterioration in ovine pulmonary embolism*

OBJECTIVE

It was hypothesized that sympathetic blockade restricted to the thoracic levels and achieved by thoracic epidural anesthesia might be capable of reducing hemodynamic deterioration after pulmonary artery embolism and that this might represent a potential method of treatment in patients with pulmonary embolism. Cardiopulmonary function after pulmonary embolism was therefore studied in sheep, either without a sympathetic blockade (the control group) or with sympathetic blockade.

DESIGN

Prospective, randomized laboratory investigation.

SETTING

University research laboratory.

SUBJECTS

Twelve adult, chronically instrumented Blackhead ewes.

INTERVENTIONS

Pulmonary embolization was achieved by injecting autologous blood clots (0.75 mL/kg) intravenously into an external jugular vein. The treatment group (n = 6) received 6 mL of 0.175% bupivacaine and the control group (n = 6) received 6 mL of 0.9% NaCl 90 mins after the embolization procedure. The injections were made via an epidural catheter (at the level of T3). Results were considered to be statistically significant (with analysis of variance) at p < .05.

MEASUREMENTS AND MAIN RESULTS

After epidural administration of bupivacaine in the thoracic epidural anesthesia group, the mean pulmonary artery pressure and heart rate were significantly reduced and the stroke volume index was significantly higher in comparison with the control group, in which the animals received epidural injections of saline.

CONCLUSIONS

Thoracic epidural anesthesia administered after the occurrence of pulmonary artery embolism thus significantly reduces hemodynamic deterioration in awake, spontaneously breathing sheep and may represent an additional option in the treatment of pulmonary embolism.

Thoracic, but not lumbar, epidural anesthesia improves cardiopulmonary function in ovine pulmonary embolism

We hypothesized that sympathetic stimulation is the main mechanism contributing to hemodynamic failure in pulmonary embolism. We investigated the effects of epidural anesthesia-induced sympathetic blockade, restricted to thoracic and lumbar levels, during pulmonary embolism. Two experiments were performed in chronically instrumented ewes. In the first experiment, six sheep received 6 mL bupivacaine 0.175% (Thoracic Epidural Anesthesia [TEA] group), and six sheep received 6 mL saline 0.9% (TEA-Control group), respectively, via an epidural catheter (T3 level). In the second experiment, six sheep received 2.8 mL bupivacaine 0.375% (Lumbar Epidural Anesthesia [LEA] group), and six sheep received 2.8 mL saline 0.9% (LEA-Control group) epidurally (L4 level). Embolization was performed by IV injection of autologous blood clots (Experiment 1, 0.75 mL/kg; Experiment 2, 0.625 mL/kg). TEA was associated with significantly slower heart rates, decreased mean pulmonary artery pressures and central venous pressures, and significantly higher stroke volume index and oxygenation in comparison with the TEA-Control group. By contrast, LEA was associated with significantly faster heart rates and increased central venous pressures and with a significantly lower stroke volume index in comparison with the LEA-Control group. TEA significantly reduced, and LEA significantly increased, hemodynamic deterioration, suggesting beneficial effects of TEA on cardiopulmonary function during pulmonary thromboembolism.

IMPLICATIONS

Thoracic (but not lumbar) epidural anesthesia was associated with beneficial cardiopulmonary effects during experimental pulmonary thromboembolism in sheep.

Excision of a giant hydatid cyst of the lung under thoracic epidural anaesthesia

We present a patient with a large pulmonary hydatid cyst compressing underlying lung, with previous pulmonary tuberculosis, who presented in respiratory failure. After institution of thoracic epidural anaesthesia employing 0.25% bupivacaine, 1% lignocaine and fentanyl, the patient was placed in the sitting position and the hydatid cyst excised and drained after a limited rib resection. An air leak persisted until the 16th postoperative day. A marked improvement in symptoms as well as in spirometly and arterial blood gases occurred, and the patient was discharged on the 20th day. Thoracic epidural anaesthesia may be a safer method than general anaesthesia for removal of a hydatid cyst in a patient with severe respiratory compromise.

Thoracic epidural analgesia: its role in postthoracotomy atrial arrhythmias

OBJECTIVE

To determine the effects of thoracic epidural analgesia (TEA) management on the incidence of atrial arrhythmias (AAs) after thoracotomy for lung resection.

DESIGN

Retrospective.

SETTING

A major university medical center.

PARTICIPANTS

The medical records of 185 consecutive patients who underwent thoracotomy between 1993 and 1997 were reviewed; patients with TEA only were included in the analysis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There was a 20% incidence of AAs after thoracotomy. Preoperative predictors of AAs were age >65 years, cardiac history, and an abnormal electrocardiogram (ECG). There was a temporal relationship between epidural catheter removal and occurrence of AAs. Fourteen patients developed AAs before TEA catheter removal, whereas 29 patients developed AAs after TEA catheter removal (p = 0.01). There was no relationship between anatomic site of epidural catheter placement or choice of epidural agent and AAs.

CONCLUSIONS

AAs after thoracotomy were common. These AAs were associated with increased age, cardiac history, abnormal ECG, increased cost, increased length of hospital stay, and time of epidural catheter removal. Although a cause-and-effect relationship cannot be inferred from this study, the presence or absence of TEA was found to have a temporal relationship with the incidence of AAs.

Inhaled nitric oxide (40 ppm) during one-lung ventilation, in the lateral decubitus position, does not decrease pulmonary vascular resistance or improve oxygenation in normal patients

OBJECTIVES

To determine the effects of inhaled nitric oxide (NO) on venous admixture (Qs/Qt), mean pulmonary artery pressure (MPAP), and pulmonary vascular resistance (PVR) in patients undergoing one-lung ventilation (1LV) in the lateral decubitus position.

DESIGN

Prospective, blinded, crossover.

SETTING

University hospital.

PARTICIPANTS

Six adult patients scheduled for thoracotomy.

INTERVENTIONS

Patients were anesthetized with thoracic epidural lidocaine, intravenous fentanyl, and inhaled isoflurane and were monitored with a systemic and pulmonary artery catheter (PAC). In the lateral decubitus position, the dependent lung was ventilated with 70% oxygen (O2) and 30% nitrogen (N2) for the control 1LV condition. For the experimental 1LV condition, the dependent lung was ventilated with the same gas concentration + NO at 40 ppm. Patients were alternated between the control and the experimental NO (40 ppm) conditions every 15 minutes for as long as the case would allow.

MEASUREMENTS AND MAIN RESULTS

During all conditions, oxygenation, Qs/Qt, and pulmonary and systemic hemodynamics were measured in a double-blinded fashion. The mean PVR during 1LV was 128 +/- 39 (SD) dyne.s.cm(-5). Inhaled NO at 40 ppm did not affect MPAP, PVR, or Qs/Qt.

CONCLUSIONS

Inhaled NO at 40 ppm, during 1LV in the lateral decubitus position, did not significantly decrease MPAP in patients with normal baseline PVR. Oxygenation and Qs/Qt did not change in this setting because MPAP was not altered. At present, interventions other than administration of inhaled NO should be applied to patients with normal PVR who experience hypoxia during one-lung ventilation.

Anesthetic considerations for parturients with primary pulmonary hypertension: review of the literature and clinical presentation

Primary pulmonary hypertension, though uncommon, is found relatively frequently in women of childbearing age and carries a high peripartum mortality. We present a patient with severe primary pulmonary hypertension who underwent two cesarean sections 3 and 6 years after the diagnosis of primary pulmonary hypertension was made. Epidural anesthesia was provided on both occasions and resulted in a good maternal and fetal outcome. We have reviewed the literature as it relates to the choice of anesthetic technique and maternal outcome in patients with primary pulmonary hypertension.

Cyanotic congenital heart disease and pregnancy: natural selection, pulmonary hypertension, and anesthesia

Pregnancy carries substantial maternal and fetal risks in patients with uncorrected or palliatively corrected cyanotic congenital heart disease (CHD). In tricuspid valve Ebstein's anomaly, pregnancy is well tolerated. Maternal mortality in tetralogy of Fallot seems to be less than 10%, but it exceeds 50% in Eisenmenger's syndrome and primary pulmonary hypertension (PPH). Maternal hematocrit greater than 60%, arterial oxygen saturation lower than 80%, right ventricular hypertension, and syncopal episodes are poor prognostic signs. Maternal risk could be reduced by vaginal delivery. Continuous monitoring of arterial and central venous pressure, electrocardiography, and pulse oximetry are recommended for every anesthetic procedure. The use of a pulmonary artery catheter is controversial and probably should be avoided in parturients with cyanotic CHD or PPH. The choice of anesthetic technique and drugs per se is of secondary importance and should be governed by individual preferences. Titration of anesthetic drugs, general anesthesia with controlled ventilation, or, preferably, regional anesthesia with spontaneous breathing should be used cautiously to avoid worsening of the preexisting condition. Prevention of excessive erythrocytosis, volume and blood loss substitution, cardiocirculatory pharmacologic support, prophylaxis of infective endocarditis, and judicious use of anticoagulant drugs should be applied as indicated by the type and presentation of CHD. Poor outcome of pregnancy in PPH requires an early consideration of heart-lung or lung transplantation. Multidisciplinary team effort and prolonged monitoring in the intensive care unit are mandatory to ensure a favorable outcome for cyanotic CHD and PPH parturients.