Room air resuscitation versus oxygen resuscitation in the delivery room

Decreased GABAB receptor function in the cerebellum and brain stem of hypoxic neonatal rats: role of glucose, oxygen and epinephrine resuscitation

Background-

Hypoxia during the first week of life can induce neuronal death in vulnerable brain regions usually associated with an impairment of cognitive function that can be detected later in life. The neurobiological changes mediated through neurotransmitters and other signaling molecules associated with neonatal hypoxia are an important aspect in establishing a proper neonatal care.

Methods-

The present study evaluated total GABA, GABA_B receptor alterations, gene expression changes in GABA_B receptor and glutamate decarboxylase in the cerebellum and brain stem of hypoxic neonatal rats and the resuscitation groups with glucose, oxygen and epinephrine. Radiolabelled GABA and baclofen were used for receptor studies of GABA and GABA_B receptors respectively and Real Time PCR analysis using specific probes for GABA_B receptor and GAD mRNA was done for gene expression studies.

Results-

The adaptive response of the body to hypoxic stress resulted in a reduction in total GABA and GABA_B receptors along with decreased GABA_B receptor and GAD gene expression in the cerebellum and brain stem. Hypoxic rats supplemented with glucose alone and with oxygen showed a reversal of the receptor alterations and changes in GAD. Resuscitation with oxygen alone and epinephrine was less effective in reversing the receptor alterations.

Conclusions-

Being a source of immediate energy, glucose can reduce the ATP-depletion-induced changes in GABA and oxygenation, which helps in encountering hypoxia. The present study suggests that reduction in the GABA_B receptors functional regulation during hypoxia plays an important role in central nervous system damage. Resuscitation with glucose alone and glucose and oxygen to hypoxic neonatal rats helps in protecting the brain from severe hypoxic damage.

Oxygen, the lead actor in the pathophysiologic drama: enactment of the trinity of normoxia, hypoxia, and hyperoxia in disease and therapy

Aerobic life has evolved a dependence on molecular oxygen for its mere survival. Mitochondrial oxidative phosphorylation absolutely requires oxygen to generate the currency of energy in aerobes. The physiologic homeostasis of these organisms is strictly maintained by optimal cellular and tissue-oxygenation status through complex oxygen-sensing mechanisms, signaling cascades, and transport processes. In the event of fluctuating oxygen levels leading to either an increase (hyperoxia) or decrease (hypoxia) in cellular oxygen, the organism faces a crisis involving depletion of energy reserves, altered cell-signaling cascades, oxidative reactions/events, and cell death or tissue damage. Molecular oxygen is activated by both nonenzymatic and enzymatic mechanisms into highly reactive oxygen species (ROS). Aerobes have evolved effective antioxidant defenses to counteract the reactivity of ROS. Although the ROS are also required for many normal physiologic functions of the aerobes, overwhelming production of ROS coupled with their insufficient scavenging by endogenous antioxidants will lead to detrimental oxidative stress. Needless to say, molecular oxygen is at the center of oxygenation, oxidative phosphorylation, and oxidative stress. This review focuses on the biology and pathophysiology of oxygen, with an emphasis on transport, sensing, and activation of oxygen, oxidative phosphorylation, oxygenation, oxidative stress, and oxygen therapy.

Do our newly graduated medical doctors have adequate knowledge about neonatal resuscitation?

CONTEXT AND OBJECTIVE

Neonatal resuscitation should be part of medical school curriculums. We aimed to evaluate medical school graduates' knowledge of neonatal resuscitation.

DESIGN AND SETTING

Cross-sectional study on the performance of candidates sitting a medical residency exam at Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, in 2004.

METHODS

There were two questions on neonatal resuscitation. One question in the theory test aimed at evaluating basic knowledge on the initial approach towards newly born infants. The question in the practical exam was designed to evaluate the candidate's ability to perform the initial steps of resuscitation and to establish bag-mask ventilation.

RESULTS

Out of 642 candidates from 74 medical schools, 151 (23.5%) answered the theory question correctly. Significantly more physicians from public medical schools in the State of São Paulo answered correctly than did those from other schools in Brazil (52.5% versus 9.2%; p < 0.05). A total of 436 candidates did the practical exam. The grades among graduates from medical schools belonging to the State of São Paulo were significantly higher than among those from other schools (5.9 +/- 2.6 versus 4.1 +/- 2.1; p < 0.001). The grades for the practical question among candidates who had answered the theory question correctly were significantly higher than those obtained by candidates who had given wrong answers (p < 0.05).

CONCLUSION

Medical school graduates' knowledge of neonate resuscitation in the delivery room is quite precarious. Emphasis on neonatal resuscitation training is urgently needed in medical schools.