Pneumothorax in a term newborn

With the advent of surfactant and gentle ventilation, the incidence of neonatal pneumothorax has decreased over the last two decades. Pneumothorax associated with respiratory distress syndrome is more common in preterm infants, but term infants often present with isolated pneumothorax. The use of CPAP or non-invasive respiratory support in the delivery room for a term infant with respiratory distress increases transpulmonary pressures and increases the risk of pneumothorax. Prompt diagnosis with a high index of suspicion, quick evaluation by transillumination, chest X-ray or lung ultrasound is critical. Management includes observation, needle thoracocentesis and if necessary, chest tube placement. This manuscript reviews the incidence, pathogenesis, diagnosis and management of a term infant with isolated pneumothorax, summarizing the combination of established knowledge with new understanding, including data on diagnostic modes such as ultrasound, reviewing preventative measures, and therapeutic interventions such as needle thoracocentesis and a comparison of pigtail vs. straight chest tubes.

Caffeine pharmacokinetics following umbilical vein injection during delayed cord clamping in preterm lambs

BACKGROUND

Spontaneous breathing during and after delayed cord clamping (DCC) stabilizes cardiopulmonary transition at birth. Caffeine stimulates breathing and decreases apnea in premature newborns. We evaluated the pharmacokinetics and physiological effects of early caffeine administration-direct injection into the umbilical vein (UV) during DCC or administered through a UV catheter (UVC) after delivery.

METHODS

Eighteen extremely premature lambs (125-127d, term gestation 145d) were exteriorized and instrumented. Lambs received caffeine-citrate at high (40 mg/kg) or standard-dose (20 mg/kg) via direct UV (DUV) injection during DCC, or via the UVC.

RESULTS

Mean peak plasma caffeine concentrations were lower with high-dose DUV compared to UVC (18 ± 4.3 vs. 46 ± 12 mg/L, p < 0.05). With standard-dose caffeine, mean peak plasma levels were 7.48 ± 2.6 with DUV and 28.73 ± 9.4 mg/L with UVC. The volume of distribution was higher in the DUV group compared to UVC (2.5 ± 1.0 vs. 0.69 ± 0.15 L/kg) with an estimated 39 ± 18% entering the maternal circulation. Maternal peak concentrations were 0.79 ± 0.71 and 1.43 ± 0.74 mg/L with standard and high-dose DUV, respectively.

CONCLUSIONS

Caffeine injected directly into the UV during DCC is feasible but achieves lower concentrations due to high volume of distribution including maternal circulation. Further trials evaluating DUV caffeine injection should use higher caffeine doses.

IMPACT

Respiratory stimulation with early caffeine may reduce the need for intubation in preterm infants. In the preterm lambs, caffeine injection directly into the umbilical vein during delayed cord clamping is feasible. Plasma caffeine concentrations are less than half when administered directly into the umbilical vein during delayed cord clamping compared to administration via an umbilical venous catheter following birth likely attributed to a larger volume of distribution or injection site leak. There were no significant hemodynamic alterations following caffeine injection.

Neonatal resuscitation with continuous chest compressions and high frequency percussive ventilation in preterm lambs

BACKGROUND

Cerebral oxygen delivery (cDO2) is low during chest compressions (CC). We hypothesized that gas exchange and cDO2 are better with continuous CC with high frequency percussive ventilation (CCC + HFPV) compared to conventional 3:1 compressions-to-ventilation (C:V) resuscitation during neonatal resuscitation in preterm lambs with cardiac arrest induced by umbilical cord compression.

METHODS

Fourteen lambs in cardiac arrest were randomized to 3:1 C:V resuscitation (90CC + 30 breaths/min) per the Neonatal Resuscitation Program guidelines or CCC + HFPV (120CC + HFPV continuously). Intravenous epinephrine was given every 3 min until return of spontaneous circulation (ROSC).

RESULTS

There was no difference in the incidence and time to ROSC between both groups. Median (IQR) PaCO2 was significantly lower with CCC + HFPV during CC, at ROSC and 15 min post-ROSC-[104 (99-112), 83 (77-99), and 43 (40-64)], respectively compared to 3:1 C:V-[149 (139-167), 153 (143-168), and 153 (138-178) mmHg. PaO2 and cDO2 were higher with CCC + HFPV during CC and at ROSC. PaO2 was similar 15 min post-ROSC with a lower FiO2 in the CCC + HFPV group 0.4 (0.4-0.5) vs. 1 (0.6-1).

CONCLUSION

In preterm lambs with perinatal cardiac-arrest, continuous chest compressions with HFPV does not improve ROSC but enhances gas exchange and increases cerebral oxygen delivery compared to 3:1 C:V during neonatal resuscitation.

IMPACT STATEMENT

Ventilation is the most important intervention in newborn resuscitation. Currently recommended 3:1 compression-to-ventilation ratio is associated with hypercarbia and poor oxygen delivery to the brain. Providing uninterrupted continuous chest compressions during high frequency percussive ventilation is feasible in a lamb model of perinatal cardiac arrest, and demonstrates improved gas exchange and oxygen delivery to the brain. This is the first study in premature lambs evaluating high frequency percussive ventilation with asynchronous chest compressions and lays the groundwork for future clinical studies to optimize gas exchange and hemodynamics during chest compressions in newborns.