Pulmonary Artery Thromboendarterectomy: A Comparison of Two Different Postoperative Treatment Strategies

Critical Care of Patients After Pulmonary Thromboendarterectomy

Pulmonary thromboendarterectomy (PTE) remains the only curative surgery for patients with chronic thromboembolic pulmonary hypertension (CTEPH). Postoperative intensive care unit care challenges providers with unique disease physiology, operative sequelae, and the potential for detrimental complications. Central concerns in patients with CTEPH immediately after PTE relate to neurologic, pulmonary, hemodynamic, and hematologic aspects. Institutional experience in critical care for the CTEPH population, a multidisciplinary team approach, patient risk assessment, and integration of current concepts in critical care determine outcomes after PTE surgery. In this review, the authors will focus on specific aspects unique to this population, with integration of current available evidence and future directions. The goal of this review is to provide the cardiac anesthesiologist and intensivist with a comprehensive understanding of postoperative physiology, potential complications, and contemporary intensive care unit management immediately after pulmonary endarterectomy.

Efficacy of a Low-Tidal Volume Ventilation Strategy to Prevent Reperfusion Lung Injury after Pulmonary Thromboendarterectomy

RATIONALE

Reperfusion lung injury is a postoperative complication of pulmonary thromboendarterectomy that can significantly affect morbidity and mortality. Studies in other postoperative patient populations have demonstrated a reduction in acute lung injury with the use of a low-tidal volume (Vt) ventilation strategy. Whether this approach benefits patients undergoing thromboendarterectomy is unknown.

OBJECTIVES

We sought to determine if low-Vt ventilation reduces reperfusion lung injury in patients with chronic thromboembolic pulmonary hypertension undergoing thromboendarterectomy.

METHODS

Patients undergoing thromboendarterectomy at one center were randomized to receive either low (6 ml/kg predicted body weight) or usual care Vts (10 ml/kg) from the initiation of mechanical ventilation in the operating room through Postoperative Day 3. The primary endpoint was the onset of reperfusion lung injury. Secondary outcomes included severity of hypoxemia, days on mechanical ventilation, and intensive care unit and hospital lengths of stay.

MEASUREMENTS AND MAIN RESULTS

A total of 128 patients were enrolled and included in the analysis; 63 were randomized to the low-Vt group and 65 were randomized to the usual care group. There was no statistically significant difference in the incidence of reperfusion lung injury between groups (32%, n=20 in the low-Vt group vs. 23%, n=15 in the usual care group; P=0.367). Although differences were noted in plateau pressures (17.9 cm H2O vs. 20.1 cm H2O, P<0.001) and peak inspiratory pressures (20.4 cm H2O vs. 23.0 cm H2O, P<0.001) between the low-Vt and usual care groups, respectively, mean airway pressures, PaO2/FiO2, days on mechanical ventilation, and ICU and hospital lengths of stay were all similar between groups.

CONCLUSIONS

In patients with chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy, intra- and postoperative ventilation using low Vts (6 mg/kg) compared with usual care Vts (10 mg/kg) does not reduce the incidence of reperfusion lung injury or improve clinical outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT00747045).

Pulmonary endarterectomy for the treatment of chronic thromboembolic pulmonary hypertension

Pulmonary endarterectomy is a curative treatment option for patients with chronic thromboembolic pulmonary hypertension (CTEPH). There is a growing body of evidence suggesting that not only patients with CTEPH but also patients with pulmonary arterial obstructions and mean pulmonary artery pressures < 25 mmHg should be offered surgery. In this review, the recent literature regarding pathophysiology, diagnostic methods, decision making by an expert CTEPH team, and surgical techniques will be summarized. Novel alternative treatment options for inoperable CTEPH patients will be discussed, i.e. targeted medical therapy and balloon pulmonary angioplasty. For the future the major task will be to define a clear selection process for the optimal treatment of the individual CTEPH patient.

Pulmonary Endarterectomy: Assessment of Operability, Surgical Description, and Post-op Care

Chronic thromboembolic pulmonary hypertension (CTEPH) is defined as a mean pulmonary artery pressure ≥25 mm Hg and pulmonary artery wedge pressure ≤15 mm Hg in the presence of occlusive thrombi within the pulmonary arteries. Surgical pulmonary thromboendarterectomy (PTE) is considered the best treatment option for CTEPH.

Effects of Open Lung Approach Policy on Mechanical Ventilation Duration in Postoperative Patients with Chronic Thromboembolism with Pulmonary Hypertension: A Case-Matched Study

Patients with chronic thromboembolism with pulmonary hypertension (CTEPH) often develop severe hypoxaemia after pulmonary thromboendarterectomy. There is reluctance to apply high positive end-expiratory pressure (PEEP) to those patients, whereas high PEEP is important for acute hypoxaemic respiratory failure due to alveolar collapse. Open lung approach (OLA) policy, a combination of recruitment manoeuvre and PEEP titration, may improve oxygenation and lung mechanics in acute hypoxaemic respiratory failure, but the effect of OLA on the outcome is unknown. We designed a case-matched, retrospective study to investigate whether OLA policy improved the outcome of postoperative patients with CTEPH.

Among 113 postoperative patients with CTEPH, 40 were chosen before and after the introduction of an OLA policy to create 1:1 ratio of case-match according to gender, age and preoperative total pulmonary resistance index (conventional treatment group vs OLA group). In the OLA group, recruitment manoeuvre was applied and then PEEP was titrated to maintain oxygenation every 12 hours. Gas exchange and duration of mechanical ventilation were compared between the groups.

The OLA group showed higher PaO2/FiO2 ratio at 12 hours after the surgery than the conventional group (P=0.0021). In the OLA group, duration of mechanical ventilation was shorter than the conventional treatment group (median, 23.5 hours vs 43 hours, P=0.0064). The OLA group showed lower cardiac index, higher pulmonary artery pressure and higher total pulmonary resistance index after the surgery than the conventional group.

The introduction of the OLA policy may have shortened mechanical ventilation duration despite what appeared to be less favorable early postoperative hemodynamics in patients after the surgery for CTEPH.