Potential role for extracorporeal membrane oxygenation cardiopulmonary resuscitation (E-CPR) during in-hospital cardiac arrest in Australia: A nested cohort study.

Objective: This study aims to evaluate the characteristics and outcomes of patients who fulfilled extracorporeal membrane oxygenation cardiopulmonary resuscitation (E-CPR) selection criteria during in-hospital cardiac arrest (IHCA). Design: This is a nested cohort study. Setting: Code blue data were collected across seven hospitals in Australia between July 2017 and August 2018. Participants: Participants who fulfilled E-CPR selection criteria during IHCA were included. Main outcome measures: Return of spontaneous circulation and survival and functional outcome at hospital discharge. Functional outcome was measured using the modified Rankin scale, with scores dichotomised into good and poor functional outcome. Results: Twenty-three (23/144; 16%) patients fulfilled E-CPR selection criteria during IHCA, and 11/23 (47.8%) had a poor outcome. Patients with a poor outcome were more likely to have a non-shockable rhythm (81.8% vs. 16.7%; p = 0.002), and a longer duration of CPR (median 12.5 [5.5, 39.5] vs. 1.5 [0.3, 2.5] minutes; p < 0.001) compared to those with a good outcome. The majority of patients (18/19 [94.7%]) achieved sustained return of spontaneous circulation within 15 minutes of CPR. All five patients who had CPR >15 minutes had a poor outcome. Conclusion: Approximately one in six IHCA patients fulfilled E-CPR selection criteria during IHCA, half of whom had a poor outcome. Non-shockable rhythm and longer duration of CPR were associated with poor outcome. Patients who had CPR for >15 minutes and a poor outcome may have benefited from E-CPR. The feasibility, effectiveness and risks of commencing E-CPR earlier in IHCA and among those with non-shockable rhythms requires further investigation.

Survival and functional outcome at hospital discharge following in-hospital cardiac arrest (IHCA): A prospective multicentre observational study.

AIM: To evaluate the functional outcome of patients after in-hospital cardiac arrest (IHCA) and to identify associations with good functional outcome at hospital discharge. METHOD: Emergency calls were prospectively screened and data collected for IHCAs in seven Australian hospitals. Patients were included if aged > 18 years, admitted as an acute care hospital in-patient and experienced IHCA; defined by a period of unresponsiveness with no observed respiratory effort and commencement of external cardiac compressions. Data collected included patient demographics, clinical and cardiac arrest characteristics, survival and functional outcome at hospital discharge using the modified Rankin Scale (mRS) and Katz Index of Independence in ADLs (Katz-ADL). RESULTS: 152 patients suffered 159 IHCAs (male 66.4%; mean age 70.2 (± 13.9) years). Sixty patients (39.5%) survived, of whom 43 (71.7%) had a good functional outcome (mRS ≤ 3) and 38 (63.3%) were independent with activities of daily living (ADLs) at hospital discharge (Katz-ADL = 6). Younger age (OR 0.95; 95% CI 0.91-0.98; p = 0.003), shorter duration of CPR (OR 0.84; 95% CI 0.77-0.91; p < 0.0001) and shorter duration of hospital admission prior to IHCA (OR 0.96; 95% CI 0.93-0.998; p = 0.04) were independently associated with a good functional outcome at hospital discharge. CONCLUSION: The majority of survivors had a good functional outcome and were independent with their ADLs at hospital discharge. Factors associated with good functional outcome at hospital discharge were identified.

The accumulation of deleterious mutations within the frozen niche variation hypothesis.

The frozen niche variation hypothesis proposes that asexual clones exploit a fraction of a total resource niche available to the sexual population from which they arise. Differences in niche breadth may allow a period of coexistence between a sexual population and the faster reproducing asexual clones. Here, we model the longer term threat to the persistence of the sexual population from an accumulation of clonal diversity, balanced by the cost to the asexual population resulting from a faster rate of accumulation of deleterious mutations. We use Monte-Carlo simulations to quantify the interaction of niche breadth with accumulating deleterious mutations. These two mechanisms may act synergistically to prevent the extinction of the sexual population, given: (1) sufficient genetic variation, and consequently niche breadth, in the sexual population; (2) a relatively slow rate of accumulation of genetic diversity in the clonal population; (3) synergistic epistasis in the accumulation of deleterious mutations.

The ecological cost of sex.

Why sex prevails in nature remains one of the great puzzles of evolution. Sexual reproduction has an immediate cost relative to asexual reproduction, as males only express their contribution to population growth through females. With no males to sustain, an asexual mutant can double its relative representation in the population in successive generations. This is the widely accepted 'twofold cost of males'. Many studies have attempted to explain how sex can recoup this cost from fitness benefits associated with the recombination of parental genotypes, but these require complex biological environments that cycle over evolutionary timescales. In contrast, we have considered the ecological dynamics that govern asexual invasion. Here we show the existence of a threshold growth rate for the sexual population, above which the invasion is halted by intraspecific competition. The asexual population then exerts a weaker inhibitory effect on the carrying capacity of the sexual population than on its own carrying capacity. The stable outcome of this is coexistence on a depleted resource base. Under these ecological circumstances, longer-term benefits of sex may eventually drive out the asexual competitor.

Inactivation of creatine kinase in physiological saline solutions.

To determine the optimal conditions for measuring the activity of creatine kinase released from isolated skeletal muscle preparations, we investigated the stability of the enzyme during storage in saline solutions of varying composition. Parameters studied were temperature, presence of albumin or dithiothreitol, calcium concentration and anionic composition. It is concluded that maximal activity is retained when samples are kept at 4 degrees C and analyzed within 24 hours in the presence of a thiol-protective compound. If longer storage periods are anticipated, inactivation is significantly retarded by addition of albumin or by decreasing the free calcium concentration of the storage salines.