Maternal hypothermia from environmental exposure in the third trimester

How cold is too cold during maternal sepsis? Navigating between maternal hypothermia and fetal bradycardia

Hypothermia is a relatively rare condition in pregnancy and has been associated with fetal bradycardia. The management of maternal hypothermia resulting in fetal bradycardia presents a challenging dilemma for healthcare professionals. Currently, no evidence exists to advise on the duration of this condition before obstetric interventions are necessary for a safe outcome for both mother and infant. We discuss a case of a 26-year old primigravida with a gestational age of 32 weeks, who presented with clinical urosepsis, resulting in severe hypothermia up to 32 degrees Celsius. Active warming measures were taken and intravenous antibiotic treatment was started. Fetal evaluation on the cardiotocogram showed prolonged bradycardia (90 BPM) prompting consideration of a cesarean section. However, after multidisciplinary consultation, conservative treatment was proposed since there were no other signs of fetal hypoxia; no decelerations, good variability and accelerations. The patient started to show clinical improvement and had a body core temperature of 36 degrees Celsius after approximately 60 h of active rewarming measures. Fetal heartrate baseline normalized as the maternal temperature raised. Subsequently the patient was discharged in good clinical condition and had an uncomplicated vaginal delivery of a healthy newborn at term. In conclusion, when fetal bradycardia occurs due to maternal hypothermia, in the absence of signs for fetal hypoxia on the cardiotocogram, treatment of the underlying maternal condition instead of immediate obstetrics intervention is the best clinical option. This strategy aims to address the underlying cause of maternal hypothermia and consequently fetal bradycardia while ensuring the well-being of both mother and fetus and preventing unnecessary premature delivery.

Environmental Exposures and Risks During Pregnancy

The Women in Wilderness Medicine Research Committee of the Wilderness Medical Society conducted a narrative review to address considerations for pregnant individuals in wilderness environments. There is limited evidence behind many opinion-based recommendations on the safety of various environmental exposures in pregnancy. The authors reviewed the literature for the best available evidence, including observational studies, case series, limited controlled trials, and extrapolation from physiological data, as well as evaluating expert consensus statements. The benefits of exposure to natural environments include better pregnancy outcomes and improved maternal mental and physical health. Risks are similar to nonpregnant individuals with the added risks associated with maternal-fetal physiology in wilderness environments and difficulties of evacuation. This narrative review discusses pregnancy-specific concerns in extreme environments, including high altitude, hypothermia, hyperthermia, lightning strikes, envenomations, and common outdoor exposures.

Hypoxia-ischemia-mediated effects on neurodevelopmentally regulated cold-shock proteins in neonatal mice under strict temperature control

BACKGROUND

Neonates have high levels of cold-shock proteins (CSPs) in the normothermic brain for a limited period following birth. Hypoxic-ischemic (HI) insults in term infants produce neonatal encephalopathy (NE), and it remains unclear whether HI-induced pathology alters baseline CSP expression in the normothermic brain.

METHODS

Here we established a version of the Rice-Vannucci model in PND 10 mice that incorporates rigorous temperature control.

RESULTS

Common carotid artery (CCA)-ligation plus 25 min hypoxia (8% O2) in pups with targeted normothermia resulted in classic histopathological changes including increased hippocampal degeneration, astrogliosis, microgliosis, white matter changes, and cell signaling perturbations. Serial assessment of cortical, thalamic, and hippocampal RNA-binding motif 3 (RBM3), cold-inducible RNA binding protein (CIRBP), and reticulon-3 (RTN3) revealed a rapid age-dependent decrease in levels in sham and injured pups. CSPs were minimally affected by HI and the age point of lowest expression (PND 18) coincided with the timing at which heat-generating mechanisms mature in mice.

CONCLUSIONS

The findings suggest the need to determine whether optimized therapeutic hypothermia (depth and duration) can prevent the age-related decline in neuroprotective CSPs like RBM3 in the brain, and improve outcomes during critical phases of secondary injury and recovery after NE.

IMPACT

The rapid decrease in endogenous neuroprotective cold-shock proteins (CSPs) in the normothermic cortex, thalamus, and hippocampus from postnatal day (PND) 11-18, coincides with the timing of thermogenesis maturation in neonatal mice. Hypoxia-ischemia (HI) has a minor impact on the normal age-dependent decline in brain CSP levels in neonates maintained normothermic post-injury. HI robustly disrupts the expected correlation in RNA-binding motif 3 (RBM3) and reticulon-3 (RTN3). The potent neuroprotectant RBM3 is not increased 1-4 days after HI in a mouse model of neonatal encephalopathy (NE) in the term newborn and in which rigorous temperature control prevents the manifestation of endogenous post-insult hypothermia.

Maternal and fetal hypothermia: more preventive compliance is required for a mother and her fetus while undergoing cesarean delivery; a quality improvement review

OBJECTIVE

Cesarean delivery is common, involves two patients, has numerous multi-disciplinary health care providers involved in the delivery management, but has variable levels of anesthesia and health services implementation for decreasing maternal hypothermia and the maternal and neonatal morbidity (and mortality). Limited implementation for either of the ERAS-CD or the ERAC guidelines, for inadvertent or preventive maternal hypothermia, is likely to be occurring on labor delivery floors. This Quality Improvement (QI) review focuses on cesarean delivery and maternal hypothermia.

METHODS

This quality and safety initiative used SQUIRE 2.0 methodology and concurrent PubMed searches to identify systematic review, meta-analysis, topic directed studies, additional published cohorts in the topic area not included in SR/MA, limited case reports that had specific clinical outcomes related to maternal hypothermia and fetal effects.

RESULTS

Two quality and safety improvement guidelines have defined the hypothermia activity element differently, with ERAS-CD recommending to prevent hypothermia, while ERAC recommending to maintain normothermia. The peer-reviewed literature indicates that the knowledge associated with surgical hypothermia outcome is known but it is not implemented for maternal cesarean delivery care. Increased maternal-effect recognition, surveillance, triage, and evidenced-based protocol management is required for the maternal - neonatal dyad undergoing cesarean delivery for the clinical reduction/prevention of neonatal hypothermia that has proven evidence-based maternal morbidity and neonatal morbidity/mortality.

CONCLUSION

TEAM-based anesthesia, obstetrical, neonatology-pediatrics and nursing research collaboration is required through quality-safety-ERAS-ERAC directed processes. Healthcare system recognition and financial support is required for maternal-fetal-neonatal hypothermia prevention protocols implementation.