Can the temporary use of right ventricular assist devices bridge patients with acute right ventricular failure after cardiac surgery to recovery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: Can the temporary use of right ventricular assist devices (RVADs) bridge patients to recovery who suffer acute right ventricular failure after cardiac surgery? More than 183 papers were found using the reported search, of which 13 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. Indications for surgical intervention included coronary artery bypass surgery, valve replacement, post-heart transplant and left ventricular assist device insertion. Significant reductions in central venous pressure (P = 0.005) and mean pulmonary artery pressures (P < 0.01) were reported during and after RVAD support. Furthermore, increases in right ventricular cardiac output (P < 0.05), right ventricular ejection fraction (P < 0.05), right ventricular stroke work (P < 0.05) and pulmonary artery oxygen saturations (P < 0.05) were also seen. Assessment by one study showed that on Day 7 after RVAD removal, the right ventricular ejection fraction had increased by up to 40%. Dynamic echocardiography studies performed before, during and after RVAD placement demonstrated that after RVAD implantation, right ventricular end-diastolic dimensions (P < 0.05) and right atrial dimensions decreased (P < 0.05) and right ventricular ejection fraction (P < 0.05) increased. Although several studies successfully weaned patients from an RVAD, there were several complications, including bleeding requiring surgical intervention. However, this may be reduced by using percutaneous implantation (bleeding incidence: 4 of 9 patients) rather than by a surgically implanted RVAD (bleeding incidence: 5 of 5 patients). However, mortality is higher in percutaneous RVAD patients rather than in surgical RVAD (80-44%) patients. Causes of death cited for patients on an RVAD included multiorgan failure, sepsis, thromboembolic events, reoccurring right heart failure and failure to wean due to persistent right ventricular failure. We conclude that RVADs have been successfully used to bridge patients to recovery after cardiac surgery; however, RVADs carry numerous risks and a high mortality rate.

Does retraction of the sternum during median sternotomy result in brachial plexus injuries?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'does retraction of the sternum during median sternotomy result in brachial plexus injuries or peripheral neuropathies?' Altogether 58 papers were found using the reported search, of which 12 represented the best evidence to answer the question. The authors, date, journal and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Caudal placement of the retractor or relieving the pressure superiorly by removing the upper blades of a retractor (P = 0.02) and use of a caudally placed symmetrical retractor has been shown to reduce neuropathy. Positioning of the patient with 'hands up' positioning showed significant reduction in the incidence of brachial plexus injuries. Furthermore, how wide the retractor is opened and use of an asymmetrical retractor for internal mammary artery (IMA) harvesting are also important factors in quantifying risk of postoperative neuropathy. Wider sternal retraction and longer bypass time did increase the risk of developing postoperative neuropathy. Three asymmetrical retractors were looked at that demonstrates the Delacroix-Chevalier to be the safest (P < 0.05). We conclude that median sternotomy risks brachial plexus injury and where possible the sternum should be opened as small a distance as possible with symmetrical retractor and using a caudally placed retractor.

Is cerebrospinal fluid drainage of benefit to neuroprotection in patients undergoing surgery on the descending thoracic aorta or thoracoabdominal aorta?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Is cerebrospinal fluid (CSF) drainage of benefit in patients undergoing surgery on the descending thoracic aorta or thoracoabdominal aorta?' Altogether 1177 papers were found using the reported search, of which 17 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. Ten of 13 studies demonstrate significant neurological protection from CSF drainage (± additional adjuncts), with two further papers showing no significant difference between patients who had or had not had CSF drainage and one study unable to provide any conclusions. For patients having surgery on the thoracic aorta or thoracoabdominal aorta CSF drainage, maintaining pressures <10 mmHg (P < 0.03), in conjunction with other neuroprotective strategies, minimizes the risk of neurological sequelae when compared with patients treated with similar adjuncts but without CSF drainage. The majority of studies used additional neuroprotective strategies, including cooling and reattachment of the intercostal arteries as adjuncts to CSF drainage. Logistic regression curves demonstrated that the longer the ischaemia time, the greater the benefit from CSF drainage (P < 0.04). Four papers observed complications of CSF drainage, of which the main complications were: catheter occlusion or dislodgement, headache, meningitis and subdural haematoma. Overall, CSF drainage does offer a neuroprotective benefit; preventing paraplegia if CSF pressures are maintained <10 mmHg.

Is it worth packing the head with ice in patients undergoing deep hypothermic circulatory arrest?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: Is it worth packing the head with ice in patients undergoing deep hypothermic circulatory arrest (DHCA)? Altogether more than 34 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question, 5 of which were animal studies, 1 was a theoretical laboratory study and 1 study looked at the ability to cool using circulating water 'jackets' in humans. There were no available human studies looking at the neurological outcome with or without topical head cooling with ice without further adjunct methods of cerebral protection. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Four papers studied animals undergoing DHCA for 45 min-2 h depending on the study design, with or without packing the head with ice. The studies all demonstrated improved cerebral cooling when the head was packed with ice during DHCA. They also illustrated an improved neurological outcome, with better behavioural scores (P < 0.05), and in some, survival, when compared with animals whose heads were not packed in ice. One study examined selective head cooling with the use of packing the head with ice during rewarming after DHCA. However, they demonstrated worse neurological outcomes in these animals, possibly due to the loss of cerebral vasoregulation and cerebral oedema. One study involved a laboratory experiment showing improved cooling using circulating cool water in cryotherapy braces than by using packed ice. They extrapolated that newer devices to cool the head may improve cerebral cooling during DHCA. The final study discussed here demonstrated the use of circulating water to the head in humans undergoing pulmonary endarterectomy. They found that tympanic membrane temperatures could be maintained significantly lower than bladder or rectal temperatures when using circulating water to cool the head. We conclude that topical head cooling with ice is of use during DHCA but not during rewarming following DHCA and that it may be possible to advance topical head cooling techniques using circulating water rather than packed ice.