ArticlesCirculatory arrest versus cerebral perfusion during pulmonary endarterectomy surgery (PEACOG): a randomised controlled trial
Introduction
Chronic thromboembolic pulmonary hypertension (CTEPH) was first described in the UK in 1951.1 It is now more widely recognised and develops in up to 3·8% of patients after acute pulmonary embolism.2 CTEPH leads to functional impairment and confers a poor prognosis,3 but many patients can be cured by pulmonary endarterectomy (PEA), having substantial improvement in symptoms and survival.4, 5, 6
For PEA to be successful, a complete surgical endarterectomy should be done, which requires a bloodless operative field to allow for precise dissection and maximum clearance of obstructive material. The most widely used technique is deep hypothermic circulatory arrest (DHCA), which allows complete cessation of blood flow and therefore optimum operating conditions. PEA surgery with DHCA leads to a reproducible reduction in pulmonary artery pressure and low in-hospital mortality.7 Because periods of DHCA are usually limited to 20 min, permanent neurological injury is rare, although complications have been reported.8 Detailed assessment of the effect of PEA with DHCA on cognitive function has not been reported.
Some surgical groups have suggested that PEA is possible with a lesser degree of hypothermia (>28°C) and reduced periods of DHCA9, 10 or partial circulatory arrest with continuous antegrade cerebral perfusion (ACP) to the brain.11 None of these alternative techniques that aim to decrease the potential morbidity from DHCA have been assessed in a randomised manner. These techniques have received criticism because of the potential risk of incomplete endarterectomy and a less successful operation.9 A fundamental compromise exists between the provision of sufficient operating time with a clear field to allow a complete endarterectomy and minimisation of the period that a patient's brain is not perfused. Other surgical procedures, mainly on the aorta, need cessation of blood circulation and use the same techniques to protect the brain while enabling surgery.
This prospective, randomised blinded study was done to compare cognitive and clinical outcomes in a homogeneous cohort of adult patients with CTEPH undergoing PEA surgery randomly allocated to either DHCA or ACP.
Section snippets
Study population
All patients aged 18–80 years who were referred to the UK national centre for PEA surgery (Papworth Hospital, Cambridge) between December, 2006, and March, 2009, were eligible to be included in the study. The institution had equal experience with both methods of cerebral management for PEA surgery when the trial started.
Patients were excluded if they could not complete cognitive functions tests (eg, sight or hearing impairments, physical barriers such as severe arthritis), were not fluent in
Results
74 of 196 screened patients were randomly allocated to one of the two treatment groups (figure 1). Overall in-hospital mortality for the whole cohort was 1·4% (1 of 74 patients) and survival at 1 year was 96% (71 of 74 patients). Characteristics of patients at baseline were much the same between the two groups (table 1).
We recorded no difference in cognitive outcome between treatment groups (Figure 2, Figure 3). For the primary outcome at 12 weeks, the mean differences between the Z scores were
Discussion
Our findings show no benefit in the maintenance of brain perfusion over temporary periods of DHCA of up to 20 min at 20°C (total cumulative time 36 min) in patients undergoing PEA. Our study shows that although perfusion of the brain might be safe, no evidence exists that it is better than DHCA, because we did not detect any difference between the groups in cognitive function measurements. Perfusion of the brain is a laudable goal, but should not detract from the importance of surgical success.
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Authors contributed equally