What is the value of topical cooling as an adjunct to myocardial protection?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'What is the value of topical cooling as an adjunct to myocardial protection?' Using the reported search, 9 papers represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The studies included four randomized controlled trials (RCTs). Two RCTs demonstrated no cardioprotective effects of topical hypothermia as they found no statistically significant differences in myocardial markers between patients with or without topical cooling. In a randomized study of 249 patients undergoing elective cardiac surgery, phrenic nerve injury and failure of extubation occurred more frequently with the use of topical hypothermia with iced slush (P = 0.009 and P = 0.034, respectively). One retrospective analysis found that patients who received iced topical hypothermia had longer postoperative hospitalization, higher incidence of atelectasis and higher left diaphragms on chest X-ray. Another study showed increased morbidity and mortality associated with postoperative diaphragmatic dysfunction resulting from the use of iced slush topical cooling of the heart. We conclude that topical cooling is an unnecessary adjunct to myocardial protection in patients undergoing cardiac surgery. There is no evidence of any additional cardioprotective benefit. Several studies showed that the use of topical hypothermia is associated with phrenic nerve injury, leading to diaphragmatic paralysis and increased pulmonary complications. Moreover, long-term follow-up data showed often incomplete regression of the phrenic nerve paralysis. However, few randomized studies exist on the value of topical cooling as an adjunct to myocardial protection.