Do we need cardiac arrest centres in Australia?

The mortality rate post admission to hospital after successful resuscitation from out‐of‐hospital cardiac arrest is high, with significant variation between regions and individual institutions. While prehospital factors such as age, bystander cardiopulmonary resuscitation and total cardiac arrest time are known to influence outcome, several aspects of post‐resuscitative care including therapeutic hypothermia, coronary intervention and goal‐directed therapy may also influence patient survival. Regional systems of care have improved provider experience and patient outcomes for those with ST elevation myocardial infarction and life‐threatening traumatic injury. In particular, hospital factors such as hospital size and interventional cardiac care capabilities have been found to influence patient mortality. This paper reviews the evidence supporting the possible development and implementation of Australian cardiac arrest centres.     

Crystalloid flush with backward unclamping may decrease post‐reperfusion cardiac arrest and improve short‐term graft function when compared to portal blood flush with forward unclamping during liver transplantation

During liver transplant (LT), the release of vasoactive substances into the systemic circulation is associated with severe hemodynamic instability that is injurious to the recipient and/or the post‐ischemic graft. Crystalloid flush with backward unclamping (CB) and portal blood flush with forward unclamping (PF) are two reperfusion methods to reduce reperfusion‐related cardiovascular perturbations in our center. The primary aim of this study was to compare these two methods. After institutional review board (IRB) approval, cadaveric whole LT cases performed between 2003 and 2008 were reviewed. Patients were divided into two groups based on reperfusion methods: CB or PF. After background matching with propensity score, the effect of each method on post‐operative graft function was assessed in detail. In our cohort of 478 patients, CB was used in 313 grafts and PF in 165. Thirty‐day graft survival was lower, and risk of retransplantation was higher in PF. Multivariable model showed that CB is an independent factor to reduce primary non‐function, cardiac arrest and improve 30‐d graft survival. Also, the incidence of ischemic‐type biliary lesions was significantly higher in the PF group. Reperfusion methods affect intraoperative hemodynamics and post‐transplant outcome. CB allows for control over temperature and composition of the perfusate, perfusion pressure, and the rate of infusion.     

Intra‐operative cardiac arrests during liver transplantation – a retrospective review of the first 15 yr in Asian population

Although many report intra‐operative cardiac arrests (ICAs) in liver transplantation (LT), the incidence, major causes, and outcome remain unclear. We aimed to investigate retrospectively, the incidence, nature, and outcome of ICA in Asian population and to identify risk factors for ICA. Consecutive 1071 LTs in an institution during 1996–2011 (adult 920, pediatric 151/living donor liver transplantation, LDLT 841, deceased donor liver transplantation, DDLT 230) were reviewed. ICA occurred in 14 adult LTs (1.5%), but none in pediatrics. ICA occurred 1.0% and 3.3% in LDLT and DDLT, respectively. Stages of ICA incidence were three at pre‐anhepatic, one at anhepatic, and 10 at neohepatic stage. Post‐reperfusion syndrome (PRS) with hyperkalemia and bleeding were the major causes of ICA. While LDLT showed miscellaneous causes for ICA at various stages, DDLT incurred ICAs at neohepatic stage only. Interestingly, we did not find pulmonary thromboembolism (PTE) to incur ICA. Risk factor analysis showed no association of pre‐operative patient condition, donor types, and intra‐operative parameters. In this review, the incidence of ICA was low in Asian population with LDLT predominance, and while PTE was not the cause of ICA, the neohepatic stage with PRS and bleeding was the most vulnerable period to anticipate ICA.     

Outcomes after cardiac arrest in an adult burn center

Objective

Adult burn patients who experience in-hospital cardiac arrest (CA) and undergo cardiopulmonary resuscitation (CPR) represent a unique patient population. We believe that they tend to be younger and have the added burden of the burn injury compared to other populations. Our objective was to determine the incidence, causes and outcomes following cardiac arrest (CA) and cardio-pulmonary resuscitation (CPR) within this population.

Methods

We conducted a retrospective review at the US Army Institute of Surgical Research (ISR) burn intensive care unit (BICU). Charts from 1st January 2000 through 31st August 2009 were reviewed for study. Data were collected all on adult burn patients who experienced in-hospital CA and CPR either in the BICU or associated burn operating room. Patients undergoing CPR elsewhere in our burn unit were excluded because we could not validate the time of CA since they are not routinely monitored with real-time rhythm strips. The study population included civilian burn patients from the local catchment area and burn casualties from the conflicts in Iraq and Afghanistan, but patients with do-not-resuscitate (DNR) orders were excluded.

Results

We found 57 burn patients who had in-hospital CA and CPR yielding an incidence of one or more in-hospital CA of 34 per 1000 admissions (0.34%). Fourteen of these patients (25%) survived to discharge while 43 (75%) died. The most common initial cardiac rhythm was pulseless electrical activity (50.9%). The most common etiology of CA among burn patients was respiratory failure (49.1%). The most significant variable affecting survival to discharge was duration of CPR (P < 0.01) with no patient surviving more than 7 min of CPR.

Conclusions

CPR in burn patients is sometimes effective, and those patients who survive are likely to have good neurological outcomes. However, prolonged CPR times are unlikely to result in return of spontaneous circulation and may be considered futile. Further, those who experience multiple CA are unlikely to survive to discharge.     

An unexpected cause of cardiac arrest during laparoscopy in an infant with supravalvar aortic stenosis

Patients with congenital supravalvar aortic stenosis (SVAS) with associated biventricular outflow tract obstruction and coronary artery abnormalities have a tenuous myocardial oxygen supply/demand relationship. They are at increased risk of acute myocardial ischemia and sudden death, especially during anesthesia. Furthermore, resuscitation during cardiac arrest is frequently unsuccessful. We report a case of perioperative cardiac arrest due to an unexpected cause in a 2 month old with SVAS during a laparoscopic Nissen fundoplication.     

Cervical Vagus Nerve Stimulation Improves Neurologic Outcome After Cardiac Arrest in Mice by Attenuating Oxidative Stress and Excessive Autophagy

BackgroundCerebral ischemia and reperfusion (I/R) induces oxidative stress and activates autophagy, leading to brain injury and neurologic deficits. Cervical vagus nerve stimulation (VNS) increases cerebral blood flow (CBF). In this study, we investigate the effect of VNS-induced CBF increase on neurologic outcomes after cardiac arrest (CA).Materials and MethodsA total of 40 male C57Bl/6 mice were subjected to ten minutes of asphyxia CA and randomized to vagus nerve isolation (VNI) or VNS treatment group. Eight mice received sham surgery and VNI. Immediately after resuscitation, 20 minutes of electrical stimulation (1 mA, 1 ms, and 10 Hz) was started in the VNS group. Electrocardiogram, blood pressure, and CBF were monitored. Neurologic and histologic outcomes were evaluated at 72 hours. Oxidative stress and autophagy were assessed at 3 hours and 24 hours after CA.ResultsBaseline characteristics were not different among groups. VNS mice had better behavioral performance (ie, open field, rotarod, and neurologic score) and less neuronal death (p < 0.05, vs VNI) in the hippocampus. CBF was significantly increased in VNS-treated mice at 20 minutes after return of spontaneous circulation (ROSC) (p < 0.05). Furthermore, levels of 8-hydroxy-2?-deoxyguanosine in the blood and autophagy-related proteins (ie, LC-3Ⅱ/Ⅰ, Beclin-1, and p62) in the brain were significantly decreased in VNS mice. Aconitase activity was also reduced, and the p-mTOR/mTOR ratio was increased in VNS mice.ConclusionsOxidative stress induced by global brain I/R following CA/ROSC leads to early excessive autophagy and impaired autophagic flux. VNS promoted CBF recovery, ameliorating these changes. Neurologic and histologic outcomes were also improved.