Oxygen administration for the resuscitation of term and preterm infants

Metyrapone alleviates deleterious effects of maternal food restriction on lung development and growth of rat offspring

Maternal food restriction (MFR) causes intrauterine growth restriction, a known risk factor for developing chronic lung disease. However, it is unknown whether this negative outcome is gender specific or preventable by blocking the MFR-induced hyperglucocorticoidism. Using a well-established rat model, we used metyrapone (MTP), an inhibitor of glucocorticoid synthesis, to study the MFR-induced lung changes on postnatal day (p) 21 in a gender-specific manner. From embryonic day 10 until delivery, pregnant dams were fed either an ad libitum diet or a 50% caloric restricted diet with or without MTP supplementation. Postnatally, the offspring were fed ad libitum from healthy dams until p21. Morphometric, Western blot, and immunohistochemical analysis of the lungs demonstrated that MTP mitigated the MFR-mediated decrease in alveolar count, decrease in adipogenic protein peroxisome proliferator-activated receptor γ, increase in myogenic proteins (fibronectin, α-smooth muscle actin, and calponin), increase in Wnt signaling intermediates (lymphoid enhancer-binding factor 1 and β-catenin), and increase in glucocorticoid receptor (GR) levels. The MFR-induced lung phenotype and the effects of MTP were similar in both genders. To elucidate the mechanism of MFR-induced shift of the adipogenic-to-myogenic phenotype, lung fibroblasts were used to independently study the effects of (1) nutrient restriction and (2) excess steroid exposure. Nutrient deprivation increased myogenic proteins, Wnt signaling intermediates, and GR, all changes blocked by protein supplementation. MTP also blocked, likely by normalizing nicotinamide adenine dinucleotide phosphate levels, the corticosterone-induced increase in myogenic proteins, but had no effect on GR levels. In summary, protein restriction and increased glucocorticoid levels appear to be the key players in MFR-induced lung disease, affecting both genders.

Delivery room management of extremely low birthweight infants shows marked geographical variations in Italy

AIM

To evaluate any geographical variations in practice and adherence to international guidelines for early delivery room management of extremely low birthweight (ELBW) infants in the North, Centre and South of Italy.

METHODS

A questionnaire was sent to all 107 directors of Italian level III centres between April and August 2012.

RESULTS

There was a 92% (n = 98) response rate. A polyethylene bag/wrap was used by 54 centres (55.1%), with the highest rate in Northern Italy (77.5%) and the lowest rate in Southern (37.7%) areas. In Northern regions, one centre (2.5%) said it used oxygen concentrations >40% to initiate positive pressure ventilation in ELBW infants. These proportions were higher in the Central (14.3%) and Southern (16.2%) areas. A T-piece device for positive pressure ventilation was more frequently available in the Northern (95%) units than in those in the Central (66.7%) and Southern (69.4%) regions. A median of 13% (IQR: 5%-30%) of ELBW infants received chest compressions at birth in Italy: 5%, 18% and 22% in Northern, Central and Southern units, respectively.

CONCLUSION

In Italy, delivery room management of ELBW infants showed marked geographical variations. Implementation of national training programmes could increase adherence to the guidelines and reduce such discordance.

Oxygen delivery using a neonatal self-inflating resuscitation bag: effect of oxygen flow

OBJECTIVE

We evaluated the effect of oxygen (O₂) flow rate on the corresponding delivered fraction of oxygen (FiO₂) during positive pressure ventilation (PPV) when using a neonatal self-inflating bag (SIB).

METHODS

Fifteen health care professionals administered PPV at a respiratory rate of 40 to 60 breaths per minute and at peak inspiratory pressures of 25 and 35 cm H₂O to a manikin by using a SIB with reservoir connected to an O₂ source equipped with a flowmeter (flow rates: 0-10 L/min). The FiO₂ corresponding to each flow rate was measured at the inflow to the facial mask for 60 seconds.

RESULTS

In total, 2520 FiO₂ data points were collected. At every O₂ flow rate, the FiO₂ gradually increased from time 0 seconds to time 60 seconds, both at 25 cm H₂O and at 35 cm H₂O. After 1 minute of PPV at 25 cm H₂O, the delivered FiO₂ was 31.5% ± 2.1% and 43.1% ± 3.1% at O₂ flow rates of 0.1 and 0.5 L/min, respectively. After 1 minute of PPV at 35 cm H₂O, the delivered FiO₂ was 29.4% ± 2.0% and 42.1% ± 4.6% at O₂ flow rates of 0.1 and 0.5 L/min, respectively. At all O₂ flow rates >5 L/min, the delivered FiO₂ was >85% and >95%, after 1 minute of PPV at 25 and 35 cm H₂O, respectively.

CONCLUSIONS

Delivered FiO₂ during PPV depends on 3 factors: oxygen flow rate, peak inspiratory pressures, and time elapsed. These data can be used to develop a scheme correlating the oxygen flow rate and the corresponding delivered FiO₂ when using a neonatal SIB.