Investigation into the effect of hyperbaric hyperoxia on serum cardiac Troponin T levels as a biomarker of cardiac injury.

Introduction: There is clinical equipoise as to whether hyperoxia is injurious to the myocardium, both in the setting of acute ischaemic insults and on the stable myocardium. This study examined the effect of extreme hyperoxia - in the form of hyperbaric oxygen treatment - on the myocardium through measurement of high-sensitivity cardiac troponin. Methods: Forty-eight individuals were enrolled to undergo a series of 30 exposures to hyperbaric oxygen for treatment of non-cardiac pathologies. High-sensitivity troponin T was measured before and after each session. Results: There was no clinically significant difference in troponin measurements following acute or recurrent sequential exposures to extreme hyperoxia, despite the studied patient population having a high rate of previous ischaemic heart disease or cardiovascular risk factors. Conclusions: This study demonstrates that profound hyperoxaemia does not induce any measurable cardiac injury at a biochemical level. Neither is there a reduction in cardiac troponin to suggest a cardioprotective effect of hyperbaric hyperoxia. This provides some reassurance as to the cardiac safety of the routine use of hyperbaric oxygen treatment in management of non-cardiac pathology.

Percutaneous Thrombin Injection: An Alternative Therapy for Iatrogenic Carotid Artery Pseudoaneurysms.

Introduction: Carotid artery pseudoaneurysm is a rare but potentially morbid complication of central venous catheter insertion. Traditionally managed by open surgical or endovascular repair, this article describes a case that used percutaneous thrombin injection. Delivered at the point of care under ultrasound guidance, it offers a less invasive and less resource dependent approach where conventional therapies are unsuccessful. Case report: A 63 year old man re-presented to hospital with a right common carotid artery pseudoaneurysm following internal jugular vein catheterisation for a staged transcatheter aortic valve implantation. An attempt was made at coil occlusion by the neuro-interventional radiology team, but this was unsuccessful given inability to pass a delivery catheter to the pseudoaneurysm tract in the setting of a tortuous and calcified proximal circulation. Subsequently, direct percutaneous thrombin injection, administered under ultrasound guidance was undertaken as an alternative approach. Complete thrombosis was achieved with no complications and the patient was discharged on day three of admission. Discussion: While percutaneous thrombin injection is commonly used in the treatment of femoral pseudoaneurysms, there remains a paucity of evidence regarding its use in the management of carotid pseudoaneurysms. This case demonstrates its effectiveness in treating this complication. Percutaneous thrombin injection may offer a highly effective treatment option for carotid pseudoaneurysm, particularly where more conventional therapies have been unsuccessful or are relatively contraindicated.

Hyperbaric oxygen therapy for acute coronary syndrome.

BACKGROUND: Acute coronary syndrome (ACS), includes acute myocardial infarction and unstable angina, is common and may prove fatal. Hyperbaric oxygen therapy (HBOT) will improve oxygen supply to the threatened heart and may reduce the volume of heart muscle that perishes. The addition of HBOT to standard treatment may reduce death rate and other major adverse outcomes.This an update of a review previously published in May 2004 and June 2010. OBJECTIVES: The aim of this review was to assess the evidence for the effects of adjunctive HBOT in the treatment of ACS. We compared treatment regimens including adjunctive HBOT against similar regimens excluding HBOT. Where regimens differed significantly between studies this is clearly stated and the implications discussed. All comparisons were made using an intention to treat analysis where this was possible. Efficacy was estimated from randomised trial comparisons but no attempt was made to evaluate the likely effectiveness that might be achieved in routine clinical practice. Specifically, we addressed:Does the adjunctive administration of HBOT to people with acute coronary syndrome (unstable angina or infarction) result in a reduction in the risk of death?Does the adjunctive administration of HBOT to people with acute coronary syndrome result in a reduction in the risk of major adverse cardiac events (MACE), that is: cardiac death, myocardial infarction, and target vessel revascularization by operative or percutaneous intervention?Is the administration of HBOT safe in both the short and long term? SEARCH METHODS: We updated the search of the following sources in September 2014, but found no additional relevant citations since the previous search in June 2010 (CENTRAL), MEDLINE, EMBASE, CINAHL and DORCTHIM. Relevant journals were handsearched and researchers in the field contacted. We applied no language restrictions. SELECTION CRITERIA: Randomised studies comparing the effect on ACS of regimens that include HBOT with those that exclude HBOT. DATA COLLECTION AND ANALYSIS: Three authors independently evaluated the quality of trials using the guidelines of the Cochrane Handbook and extracted data from included trials. Binary outcomes were analysed using risk ratios (RR) and continuous outcomes using the mean difference (MD) and both are presented with 95% confidence intervals. We assessed the quality of the evidence using the GRADE approach. MAIN RESULTS: No new trials were located in our most recent search in September 2014. Six trials with 665 participants contributed to this review. These trials were small and subject to potential bias. Only two reported randomisation procedures in detail and in only one trial was allocation concealed. While only modest numbers of participants were lost to follow-up, in general there is little information on the longer-term outcome for participants. Patients with acute coronary syndrome allocated to HBOT were associated with a reduction in the risk of death by around 42% (RR: 0.58, (95% CI 0.36 to 0.92), 5 trials, 614 participants; low quality evidence).In general, HBOT was well-tolerated. No patients were reported as suffering neurological oxygen toxicity and only a single patient was reported to have significant barotrauma to the tympanic membrane. One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, 95% CI 1.92 to 521). AUTHORS' CONCLUSIONS: For people with ACS, there is some evidence from small trials to suggest that HBOT is associated with a reduction in the risk of death, the volume of damaged muscle, the risk of MACE and time to relief from ischaemic pain. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified from this review.

Patent foramen ovale influences the presentation of decompression illness in SCUBA divers.

BACKGROUND: Few have examined the influence of patent foramen ovale (PFO) on the phenotype of decompression illness (DCI) in affected divers. METHODOLOGY: A retrospective review of our database was performed for 75 SCUBA divers over a 10-year period. RESULTS: Overall 4,945 bubble studies were performed at our institution during the study period. Divers with DCI were more likely to have positive bubble studies than other indications (p<0.001). Major DCI was observed significantly more commonly in divers with PFO than those without (18/1,000 v.s. 3/1,000, p=0.02). Divers affected by DCI were also more likely to require a longer course of hyperbaric oxygen therapy (HBOT) if PFO was present (p=0.038). If the patient experienced one or more major DCI symptoms, the odds ratio of PFO being present on a transoesophageal echocardiogram was 3.2 (p=0.02) compared to those who reported no major DCI symptoms. CONCLUSION: PFO is highly prevalent in selected SCUBA divers with DCI, and is associated with a more severe DCI phenotype and longer duration of HBOT. Patients with unexpected DCI with one or more major DCI symptoms should be offered PFO screening if they choose to continue diving, as it may have considerable prognostic and therapeutic implications.

Hyperbaric oxygen therapy for acute coronary syndrome.

BACKGROUND: Acute coronary syndrome (ACS), includes acute myocardial infarction and unstable angina, is common and may prove fatal. Hyperbaric oxygen therapy (HBOT) will improve oxygen supply to the threatened heart and may reduce the volume of heart muscle that perishes. The addition of HBOT to standard treatment may reduce death rate and other major adverse outcomes. OBJECTIVES: To assess the benefits and harms of adjunctive HBOT for treating ACS. SEARCH STRATEGY: We updated the search of the following sources in June 2010, finding one further trial: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, DORCTHIM, LILACS and checked the references from selected articles. Relevant journals were handsearched and researchers in the field contacted. No language restrictions were applied. SELECTION CRITERIA: Randomised studies comparing the effect on ACS of regimens that include HBOT with those that exclude HBOT. DATA COLLECTION AND ANALYSIS: Three reviewers independently evaluated the quality of trials using the guidelines of the Cochrane Handbook and extracted data from included trials. MAIN RESULTS: Six trials with 665 participants contributed to this review. There was a significant decrease in the risk of death with HBOT (risk ratio (RR) 0.58, 95% CI 0.36 to 0.92, P = 0.02). The extent of heart muscle damage was lower following HBOT, as shown by a lesser rise in muscle enzyme in the blood (mean difference (MD) 493 IU, P = 0.005) and a better LVEF (MD 5.5%, P = 0.001). There was evidence from individual trials of reductions in the risk of major adverse coronary events (MACE) (RR 0.12, P = 0.03); re-infarction (RR 0.28, P = 0.04) and dysrhythmias following HBOT (RR 0.59, P = 0.01, and the time to relief of pain was reduced with HBOT (MD 353 minutes shorter, P < 0.00001). One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, P = 0.02). AUTHORS' CONCLUSIONS: For people with ACS, there is some evidence from small trials to suggest that HBOT is associated with a reduction in the risk of death, the volume of damaged muscle, the risk of MACE and time to relief from ischaemic pain. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified from this review.