RESUMO
OBJECTIVE: To evaluate the frequency and interrelationships among neonatal near miss (NNM) criteria and the anticipated workload for audits in high-income countries. DESIGN: Observational retrospective descriptive study. SETTING: Tertiary maternal and neonatal units at Mater Mothers' Hospital, Brisbane, Queensland, Australia. PARTICIPANTS: Cases of stillbirths (n = 483), neonatal deaths (n = 203), and live births (n = 66,353) from January 2016 to July 2022 (N = 67,039). METHODS: We identified eight prespecified NNM criteria nominated by perinatal experts. Primary outcomes were NNM frequency, their interrelationships, and related workload. We used descriptive statistics and analysis of variance and considered p < .05 significant. RESULTS: We found 2,243 unique NNM cases (33.7/1,000 live births). The NNM ratio per 1,000 live births according to each of the eight criteria were: unplanned resuscitation at birth (25.09/1,000 live births), birth asphyxia needing surveillance for hypoxic ischemic encephalopathy (8.46/1,000 live births), metabolic acidosis at birth (8.04/1,000 live births), advanced resuscitation at birth (3.68/1,000 live births), seizures and/or stroke (0.96/1,000 live births), severe intraventricular hemorrhage and/or cerebellar hemorrhage (0.95/1,000 live births), moderate to severe hypoxic ischemic encephalopathy (0.9/1,000 live births), and severe birth trauma (0.44/1,000 live births). Almost one third of NNM cases met more than one criterion. Anticipated workload for monthly NNM audits varied from 0.04 to 2.8 cases per 1,000 live births. CONCLUSION: Different sets of NNM criteria considerably alter the frequency of NNMs and the anticipated workload for NNM audits. Their interrelationships are likely attributable to the fact that some of the criteria are risk factors for or are part of the causal pathway for other NNM criteria. These findings can assist with the determination of a pragmatic NNM definition considering the feasibility of NNM audits in high-income countries.
RESUMO
Human activities are increasing both the frequency of hypoxic episodes and the mean temperature of aquatic ecosystems, but few studies have considered the possibility that acclimation to one of these stressors could improve the ability to cope with the other stressor. Here, we used Atlantic killifish, Fundulus heteroclitus, to test this hypothesis. Hypoxia tolerance was measured as time to loss of equilibrium in hypoxia (LOEhyp) at 0.4 kPa oxygen. Time to LOEhyp declined from 73.3 ± 6.9 min at 15 °C to 2.6 ± 3.8 min at 23 °C, and at 30 °C no fish could withstand this level of hypoxia. Prior acclimation to warm temperatures significantly increased time to LOEhyp. Hypoxia tolerance of the southern subspecies of killifish, F. heteroclitus heteroclitus, was greater than that of the northern subspecies, F. heteroclitus macrolepidotus, measured both as critical oxygen tension (Pcrit) and as time to LOEhyp. Warm acclimation offset the negative effects of temperature on time to LOEhyp to a similar extent in the two subspecies. Warm acclimation increased total lamellar surface area of the gill in both subspecies as a result of regression of an interlamellar cell mass (ILCM). However, differences in total lamellar surface area could not explain differences in time to LOEhyp between the subspecies, suggesting that the lower time to LOEhyp of northern fish is related to their higher routine metabolic rate. These data suggest that thermal plasticity in gill morphology can improve the capacity of this species to tolerate hypoxia, and shows how existing plasticity may help organisms to cope with the complex interacting stressors that they will encounter with increasing frequency as our climate changes.