Hyperbaric oxygen therapy in carbon monoxide poisoning in pregnancy: Maternal and fetal outcome

Maternal exposure to hyperbaric oxygen at the preimplantation stages increases apoptosis and ectopic Cdx2 expression and decreases Oct4 expression in mouse blastocysts via Nrf2-Notch1 upregulation and Nf2 downregulation

BACKGROUND

The environmental oxygen tension has been reported to impact the blastocyst quality and cell numbers in the inner cell mass (ICM) during human and murine embryogenesis. While the molecular mechanisms leading to increased ICM cell numbers and pluripotency gene expression under hypoxia have been deciphered, it remains unknown which regulatory pathways caused the underweight fetal body and overweight placenta after maternal exposure to hyperbaric oxygen (HBO).

RESULTS

The blastocysts from the HBO-exposed pregnant mice revealed significantly increased signals of reactive oxygen species (ROS) and nuclear Nrf2 staining, decreased Nf2 and Oct4 expression, increased nuclear Tp53bp1 and active caspase-3 staining, and ectopic nuclear signals of Cdx2, Yap, and the Notch1 intracellular domain (N1ICD) in the ICM. In the ICM of the HBO-exposed blastocysts, both Nf2 cDNA microinjection and Nrf2 shRNA microinjection significantly decreased the ectopic nuclear expression of Cdx2, Tp53bp1, and Yap whereas increased Oct4 expression, while Nrf2 shRNA microinjection also significantly decreased Notch1 mRNA levels and nuclear expression of N1ICD and active caspase-3.

CONCLUSION

We show for the first time that maternal exposure to HBO at the preimplantation stage induces apoptosis and impairs ICM cell specification via upregulating Nrf2-Notch1-Cdx2 expression and downregulating Nf2-Oct4 expression.

Hydranencephaly following carbon monoxide poisoning during pregnancy: An uncommon and potentially fatal complication in infant

BACKGROUND

Hydranencephaly is a rare malformation of the brain system with an incidence of 0.5 per 1000 births. Its principal etiologies are bilateral occlusion of the internal carotid arteries and congenital infections.

CASE

We reported an uncommon case of hydranencephaly diagnosed in 50-day old infant and attributable to carbon monoxide (CO) poisoning during the first trimester of pregnancy.

CONCLUSIONS

We recommend a prompt diagnosis and management of CO poisoning in pregnant women since it can dramatically affect both the fetus and mother.

Narrative minireview of the current status of hyperbaric oxygen therapy for pregnant women

We performed a narrative minireview for a PubMed search on March 31, 2023, using the keywords "pregnant" and "hyperbaric oxygen" to identify any related articles. Most reports have described pregnant women with carbon monoxide (CO) poisoning being treated by hyperbaric oxygen therapy (HBOT). HBOT helped improve the maternal condition and ensure normal fetal development. Some pregnant women with CO poisoning treated by HBOT suffered abortions or gave premature birth to low-weight babies or with congenital malformations. However, these results were considered sequelae of CO poisoning, not HBOT. We hypothesized that for pregnant women facing a life-threatening situation, for which the effectiveness of HBOT has previously been suggested, prioritizing the stabilization of the mother may also be beneficial for normal fetal development.

Should We Use Hyperbaric Oxygen for Carbon Monoxide Poisoning Management? A Network Meta-Analysis of Randomized Controlled Trials

Carbon monoxide (CO) poisoning is a public health issue in numerous countries. Oxygen supplementation is the standard and initial management for acute CO poisoning. Normobaric oxygen (NBO) and hyperbaric oxygen (HBO) therapies for CO poisoning have been discussed for several decades. NBO, one-session HBO, two-session HBO, and three-session HBO have not been clearly compared, although there are some syntheses. Therefore, this study aimed to provide an overview of various HBO therapies for CO poisoning. We searched online databases for randomized controlled trials (RCTs) on this topic, and two authors individually extracted data on characteristics, mortality, headache recovery, general fatigue, memory impairment, and difficulty concentrating. Outcomes were pooled using network meta-analysis. We included eight RCTs (n = 1785) that met our eligibility criteria. Pooled estimates showed that HBO had no better outcomes than NBO. Moreover, two-session HBO seemed to have a higher general fatigue rate than NBO, and compared with one-session HBO therapy, it had a higher fatigue rate (risk ratio (RR): 1.29, 95% confidence interval (CI): 1.03–1.62), memory impairment rate (RR = 1.80, 95% CI: 1.01–3.19), and concentration impairment rate (RR = 1.85, 95% CI: 1.19–2.89). HBO may be ineffective for patients with CO poisoning. Therefore, clinicians should consider the available treatment options carefully before recommending HBO to patients.

Perinatal Carbon Monoxide Poisoning: Treatment of a 2-Hour-Old Neonate with Hyperbaric Oxygen

A 41-year-old gravida 4 para 3 (G4P3) and 38 ^5/7 weeks pregnant woman presented to labor and delivery with dizziness, headache, and decreased fetal movement after 12 hours of exposure to carbon monoxide (CO) from a grill that was used inside for heat. The mother was hemodynamically stable, and her neurologic examination was intact. Her carboxyhemoglobin level, which was obtained 12 hours after removal from the CO exposure, was 7.4%. The fetus's heart rate was 173 beats per minute with moderate variability and one late appearing deceleration, not associated with contractions. The biophysical profile score was 2 of 8. The obstetrics team performed a routine cesarean section. The 1- and 5-minute Apgar's scores were 7 and 8, respectively. The arterial cord gas result was as follows: pH = 7.05, PCO ₂  = 71 mm Hg, pO ₂  = 19 mm Hg, bicarbonate = 14 mmol/L, and carboxyhemoglobin = 11.9%. The mother and infant were treated with hyperbaric oxygen therapy consisting of 100% oxygen at 2.4 atmosphere absolutes (ATA) for 90 minutes at 2.5 hours after delivery. Following one hyperbaric oxygen treatment, the infant was transitioned to room air and routine postpartum treatment and was discharged 3 days later in good condition. Hyperbaric oxygen treatment was well tolerated in this neonate.

A General Overview on the Hyperbaric Oxygen Therapy: Applications, Mechanisms and Translational Opportunities

Hyperbaric oxygen therapy (HBOT) consists of using of pure oxygen at increased pressure (in general, 2-3 atmospheres) leading to augmented oxygen levels in the blood (Hyperoxemia) and tissue (Hyperoxia). The increased pressure and oxygen bioavailability might be related to a plethora of applications, particularly in hypoxic regions, also exerting antimicrobial, immunomodulatory and angiogenic properties, among others. In this review, we will discuss in detail the physiological relevance of oxygen and the therapeutical basis of HBOT, collecting current indications and underlying mechanisms. Furthermore, potential areas of research will also be examined, including inflammatory and systemic maladies, COVID-19 and cancer. Finally, the adverse effects and contraindications associated with this therapy and future directions of research will be considered. Overall, we encourage further research in this field to extend the possible uses of this procedure. The inclusion of HBOT in future clinical research could be an additional support in the clinical management of multiple pathologies.

Hypoxia: A teratogen underlying a range of congenital disruptions, dysplasias, and malformations

In this review, we explore evidence that hypoxia in the developing human fetus can lead not only to the more commonly accepted disruptive-type defects, but also patterns of anomalies that suggest that hypoxia can exert a more classic teratogenic effect, using the brain as one example. We review neuropathology in the context of intrauterine hypoxia, particularly as it relates to carbon monoxide poisoning, in utero strokes, and homozygous alpha-thalassemia. In general, the associated brain injuries resemble those seen with other causes of hypoxic-ischemic injury. Fetal strokes during development usually lead to loss of brain tissue in areas that do not follow a typical embryologic pattern, and therefore are considered disruptions. However, there is also evidence that fetal brain ischemia can cause more classically recognized patterns of abnormal embryonic neuronal migration and organization such as polymicrogyria, cortical dysplasia, or dysgenesis, including select types of focal cortical dysplasia. This study summarizes available literature and evidence to raise clinicians' awareness regarding the association between hypoxia and congenital anomalies, including brain malformations.