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Intratracheal pulmonary ventilation (ITPV) enhances the clearance of CO, from dead space and lungs by a bias flow of gas administered in the distal trachea. ITPV flow is continuously administered through a separate catheter placed within an endotracheal tube (ETT). After exiting from catheter's tip in the distal trachea, the flow of gas is redirected outward away from the lungs. We hypothesized that, compared with conventional mechanical ventilation (CMV), ITPV may increase minute CO, clearance (vco,), reduce the partial pressure of CO, dioxide in arterial gas (Paco,), and reduce distal tracheal peak inspiratory pressure (dPIP). We induced surfactant deficiency in 15 adult rabbits by lung lavage with 10 mL/kg normal saline. Animals were ventilated through a double-lumen 4.0 ETT, inserted through a tracheotomy incision. dPIP, distal positive end expiratory pressure, and distal mean airway pressure were monitored, and the mean exhaled CO, concentration was measured. For ventilator rates (respiratory rate) of 30, 45, and 70 breathslmin, the study included two phases: phase I compared CO, clearance and Paco, between ITPV and CMV using similar ventilatory pressures; phase I1 evaluated the effectiveness of ITPV in reducing dPIP and tidal volume (V,), compared with CMV, while maintaining eucapnea. When comparing ITPV and CMV, the following results (mean t SD) were achieved at respiratory rate of 30, 45, and 70 breathslmin, respectively. Phase I ITPV resulted in mean percent reduction of Paco, by 3 1.4 i lo%, 37.1 i 9.7% and 38.3 +-9%; mean percent increase in Vco, by 61.3 i 29%, 56 i 23%, and 98 t 40%, compared with CMV. Phase I1 ITPV resulted in mean percent reduction of dPIP by 35.5 t 14%, 38 i 10.8%, and 37.2 t 13.7%, and mean percent reduction in V, by 34.7 t 12.9%, 36.4 i 15%, and 52.7 t 10.7%, compared with CMV. The changes in Paco,, vco, (phase I), and dPIP and V, (phase 11) were all significantly more than 25% (p < 0.05). Oxygenation and pH were not significantly different between ITPV and CMV. We conclude that, in a surfactant deficiency rabbit model, ITPV is an efficient mode of assisted ventilation that increases CO, clearance and reduces ventilator pressures required for adequate ventilation. We speculate that ITPV can minimize lung barotrauma associated with mechanical ventilation. (Pediatr Res 38: 878-885, 1995) Abbreviations CMV, conventional mechanical ventilation dP,,, distal mean airway pressure dPEEP, distal positive end expiratory pressure dPIP, distal peak inspiratory pressure ETT, endotracheal tube ITPV, intratracheal pulmonary ventilation PFT, pulmonary function test RR, respiratory rate Vco,, minute CO, clearance V,, dead space volume V,, tidal volume Paco,, partial pressure of CO, in arterial gas Pao,, partial pressure of 0, in arterial gas Fio,, fraction of inspired 0, I:E ratio, inspiratory:expiratory ratio F,CO,, mean exiting CO, concentration v,, expiratory minute volume TI, inspiratory time T,, expiratory time ECMO, extracorporeal membrane oxygenation Intratracheal pulmonary ventilation is...

Rationale Little is known about the polysomnogram (PSG) characteristics in infants with bronchopulmonary dysplasia (BPD), especially severe BPD, who do not need home ventilatory support but are at increased risk for chronic hypoxia and are vulnerable to its effects. Objective This study aims to assess PSG characteristics and change in discharge outcomes in premature infants with BPD who required oxygen therapy at discharge. Methods This is a retrospective chart review of premature infants with BPD who were admitted to a quaternary newborn and infant intensive care unit from January 1, 2012 to December 31, 2015 and who underwent polysomnography before discharge. Measurements and Main Results Data from 127 patients were analyzed. The median gestational age of our patients was 26 weeks and 1 day (interquartile range [IQR]: 24.71, 28.86). The majority of the patients had moderate‐to‐severe BPD. The median obstructive apnea−hypopnea index was 5.3 events/h (IQR: 2.2, 10.1). The median oxygen desaturation index was 15.7 events/h (IQR: 4.7, 35). Nadir oxygen saturation measured by pulse oximeter was 81% (IQR: 76−86) and the arousal/awakening index was 21.9 (IQR: 13.3−30.9). No statistically significant difference was noted between severe and nonsevere BPD groups for PSG characteristics. However, average end‐tidal CO2 was significantly higher in the severe BPD group (p = .0438). Infants in the severe BPD group were intubated longer than infants with nonsevere BPD (p = .0082). The corrected gestational age (CGA) at the time of discharge (CGA‐PSG) and PSG (CGA‐DC) was higher in severe BPD patients but not statistically different. The majority of premature infants who underwent a PSG were discharged home with oxygen, and 69% required a titration of their level of support based on results from the PSG. Conclusion Our results highlight the presence of abnormal PSG characteristics in BPD patients, as early as 43 weeks CGA. These findings have not been previously described in this patient population prior to initial discharge from the hospital. A severe BPD phenotype tends to be associated with higher respiratory morbidity compared with a nonsevere BPD phenotype for the comparable CGA. PSG, when available, may be helpful for individualizing and streamlining treatment in preparation for discharge home and mitigating the effects of intermittent hypoxic episodes.

SummaryWe sought to test the hypothesis that hyperinsulinemia per se alters the flux of surface active material (SAM) into tracheal fluid by continuously infusing insulin (0.24 + 0.04 units/kg/hr, mean + S.E.) from 112 through 135 days gestation into five chronically catheterised fetal lambs, from which tracheal fluid could be collected.Serum insulin levels in these fetuses (95 f 10 pU/ml) were greater than in five chronically catheterised control fetuses of the same gestational age (10 f 1 pU/ml, P < 0.001) and in the mothers (33 + 6 pU/ml, P < 0.001). Serum glucose levels in the insulin-treated fetuses (10 k 1 mg/dl) were lower than in the control fetuses (19 + 1 mg/dl, P < 0.001) and in the mothers (60 f 3 mg/dl, P < 0.001). Arterial blood gases (pH 7.37 + 0.01, Po2 23.3 + 0.05 mm Hg, Pcoz 41.5 f 0.9 mm Hg) and hematocrit (33 + 1% at 127 days gestation and 31 + 1% at 135 days gestation) in the insulin treated fetuses were not different from the controls.SAM flux into the tracheal fluid of the insulin-treated fetuses was 1 pg/kg/hr, coefficient of variation 373%. This was lower than SAM flux in the control fetuses (26 pg/kg/hr, coefficient of variation 28%, P < 0.01). Moreover, among the control fetuses, SAM began to appear in tracheal fluid at 119 days gestation and was present in all five fetuses by 125 days gestation, whereas SAM did not begin to appear in the insulin-treated fetuses until 127 days gestation and did not appear at all in three of them. SpeculationChronic hyperinsulinemia reduces surface active material flux into tracheal fluid of fetal lambs. This effect may be partially mediated by reduced substrate (glucose) availability for surface active material phospholipid synthesis, storage, and/or secretion.The incidence of respiratory distress syndrome is reported by Robert et al. (21) to be increased almost 6-fold in infants of diabetic mothers, even when suitable corrections are made for gestational age. However, RDS may be less prevalent when maternal diabetes is mild and well controlled (7,8). The infants of diabetic mothers experiences hyperinsulinemia both in utero and in the postnatal period (2,10,12,16,22), particularly when glucose homeostasis is poor (24).Stubbs and Stubbs (28) have hypothesised that fetal hyperinsulinemia may be the common link between maternal diabetes mellitus and respiratory distress syndrome. Stubbs et al. (27) reported that the glucose uptake of isolated perfused rat lung increased by 30% in the presence of physiologic concentrations of ilisulin. Sosenko et al. (26) and Rhoades et al. (20) found evidence of delayed lung maturation in fetuses of glucose intolerant rabbits and rats respectively. Also, Smith et al. (23) found that, in the presence of glucocorticoids, lecithin synthesis by cultured fetal lung cells decreased in response to higher concentrations of insulin. In addition, Gross et al. (9) have indicated that insulin delays the morphologic maturation of fetal rat lung cultures, causing a decrease in the number of lamellar bodies and alveolar type I1 ce...