Artery Pressure In Infants Research Articles

Echocardiographic Assessment of Pulmonary Arterial Hypertension Following Inhaled Nitric Oxide in Infants with Severe Bronchopulmonary Dysplasia

Objectives: Inhaled nitric oxide (iNO) is an effective pulmonary vasodilator. However, the efficacy of iNO in former premature infants with established bronchopulmonary dysplasia (BPD) has not been studied. This study aimed to determine the efficacy of iNO in reducing pulmonary artery pressure in infants with severe BPD as measured by echocardiography. Study Design: Prospective, observational study enrolling infants born at less than 32 weeks gestation and in whom (1) iNO therapy was initiated after admission to our institution, or (2) at the outside institution less than 48 h before transfer and received an echocardiogram prior to iNO initiation, and (3) had severe BPD. Data were collected at three time-points: (1) before iNO; (2) 12–48 h after initiation of iNO; and (3) 48–168 h after initiation of iNO. The primary outcome was the effect of iNO on pulmonary artery pressure measured by echocardiography in patients with severe BPD between 48 and 168 h after initiating iNO therapy. Results: Of 37 enrolled, 81% had echocardiographic evidence of pulmonary arterial hypertension (PAH) before iNO and 56% after 48 h of iNO (p = 0.04). FiO2 requirements were significantly different between time-points (1) and (3) (p = 0.05). There were no significant differences between Tricuspid Annular Plane Systolic Excursion (TAPSE) Z-Scores, time to peak velocity: right ventricular ejection time (TPV:RVET), and ventilator changes. Conclusions: Although we found a statistically significant reduction of PAH between time-point (1) and (3), future trials are needed to further guide clinical care.

The Effect of Perioperative Administration of Treprostinil in Infants with Non-restrictive Ventricular Septal Defect and Severe Pulmonary Arterial Hypertension.

This study investigated the efficacy and safety of intravenous treprostinil during the perioperative period in infants with non-restrictive ventricular septal defect (VSD) and severe pulmonary arterial hypertension (PAH) undergoing surgical VSD repair. This was a retrospective study. There were 79 infants with non-restrictive VSD and severe PAH receiving surgical treatment from January to December 2019 in our cardiac center. The patients were divided into the treprostinil group and control group according to whether intravenous treprostinil was used during the perioperative period. There were no significant differences in the preoperative characteristics, including age, sex, weight, ventricular size, or preoperative pulmonary artery pressure, between the two groups. Although the pulmonary artery pressure in both groups was significantly lower postoperatively than preoperatively, the postoperative pulmonary artery systolic pressure was significantly lower in group T than in group C. The postoperative mechanical ventilation time, ICU stay, and hospital stay in group T were shorter than those in group C. Treprostinil can be used effectively and safely to reduce the perioperative pulmonary artery pressure in infants with non-restrictive VSD and severe PAH undergoing surgical VSD repair.

119 Doppler Assessment of Pulmonary Artery Pressure in Very Low Birth Weight Infants at Risk of Chronic Lung Disease

Background: Chronic lung disease (CLD) is mainly confined to very low birthweight (VLBW) infants and is a significant cause of morbidity and mortality. It appears that pulmonary hypertension plays an important part in the physiopathology of CLD and has been linked to the increased incidence of death in infants with CLD. Doppler echocardiography allows to assess non-invasively pulmonary artery pressure in these infants. The objectives are: first, to evaluate the pulmonary artery pressure changes in VLBW infants at risk of CLD, and second, to determine whether Doppler evaluation can detect the infants at risk to develop CLD.

Echocardiographic evidence of improved hemodynamics during inhaled nitric oxide therapy for persistent pulmonary hypertension of the newborn.

To evaluate the cardiovascular effects of inhaled nitric oxide (NO) on the systemic and pulmonary circulations, 25 consecutive infants with severe persistent pulmonary hypertension of the newborn (PPHN) underwent serial echocardiographic evaluations before and during inhaled NO therapy. Estimation of the systolic pulmonary artery pressure (SPAP) was derived from measurement of a tricuspid regurgitant jet using Bernoulli's equation. We also derived a pulmonary/systemic pressure ratio to evaluate overall cardiopulmonary effects. Paired measurements of estimated SPAP decreased from 62.0 +/- 3.8 mmHg to 44.7 +/- 4.3 mmHg (p < 0.01) during inhaled NO therapy. The pulmonary/systemic pressure ratio decreased from 0.98 +/- 0.06 to 0.59 +/- 0.04 during NO therapy (p < 0.01), indicating a significant decline in the vascular resistance between the two circulations. These changes also correlated with changes in the extrapulmonary shunt patterns at the ductus arteriosus and foramen ovale seen during inhaled NO therapy. The decreased right-to-left shunting was accompanied by a parallel (64%) improvement in systemic oxygenation, with the alveolar-arterial oxygen gradient (A-a DO2) falling from 591 +/- 14 mmHg to 380 +/- 33 mmHg (p < 0.01). We found echocardiography to be a useful clinical tool for evaluating and monitoring pulmonary artery pressure in infants with PPHN. Measurement of the SPAP and the pulmonary/systemic pressure ratio gave a quantitative estimation of the severity of PPHN, and the extrapulmonary shunt flow patterns at the ductus arteriosus and foramen ovale gave qualitative estimates of its severity. Inhaled NO increased pulmonary blood flow and oxygenation and improved the systemic cardiopulmonary hemodynamics in this group of infants.

Change of complex and periodic heart rate dynamics with change of pulmonary artery pressure in infants with left-to-right shunt lesion

We studied how complex and periodic heart rate dynamic changed as pulmonary artery pressure elevated in 32 infants with ventricular septal defect. In addition, we tested the possibility that the dynamical change could be used to predict the pulmonary artery pressure noninvasively. During cardiac catheterization, mean pulmonary artery pressure was measured and, at the same time, 5-min segments of continuous electrocardiographic recording was stored into computer files. High- (>0.15 hertz) and low- (0.03–0.15 hertz) frequency components of heart rate variability were computed using spectral analysis. The overall complexity of heart rate time series was quantified by its approximate entropy. Pulmonary hypertensive infants (mean pulmonary artery pressure >20 mm Hg, n=17) have significantly lower low- ( p<0.05) and high- ( p<0.05) frequency power and lower approximate entropy ( p<0.0001) than pulmonary normotensive infants (mean pulmonary artery pressure ≤20 mm Hg, n=15). The mean pulmonary artery pressure is significantly correlated not with the spectral powers but with the approximate entropy ( r=−0.71, p=0.0001). It can be concluded that, in infants, pulmonary hypertension induced by left- to-right shunt lesions suppresses both periodic and complex heart rate oscillation and that mean pulmonary artery pressure can be predicted by calculating the approximate entropy of heart rate variability.

Changes in pulmonary artery pressure in infants with respiratory distress syndrome following treatment with Exosurf.

The pulmonary artery pressure (PAP) changes were studied using Doppler echocardiography in preterm infants treated with an artificial surfactant (Exosurf) during the acute phase of respiratory distress syndrome (RDS). The ratio of pulmonary artery acceleration time to the right ventricular ejection time (AT:RVET), measured from the Doppler wave form, was determined in 38 infants before the first dose of Exosurf, at one and six hours after the first dose, immediately before the second dose of Exosurf, and at one, six, 12, 36, and 60 hours subsequently. The median AT:RVET ratio corrected for heart rate (AT:RVET(c)) increased significantly an hour after administration of the first dose of Exosurf from 0.330 (0.273-0.410) to 0.380 (0.303-0.445) and similarly an hour after the second dose from 0.426 (0.252-0.495) to 0.440 (0.373-0.500). These changes occurred against a steady increase in the median AT:RVET(c) over the first 72 hours. It is concluded that the reduction in PAP correlates well with clinical parameters of disease severity and raises questions regarding the mode of action of Exosurf.

Raised pulmonary artery pressure in very low birthweight infants requiring supplemental oxygen at 36 weeks after conception.

This study aimed to investigate the changes in pulmonary artery pressure in infants with chronic lung disease who then developed prolonged oxygen dependency. The time to peak velocity: right ventricular ejection time (TPV:RVET) ratio calculated from the Doppler waveform, which correlates negatively with pulmonary artery pressure, was used. Thirty four infants with chronic lung disease were studied. At 36 weeks after conception 19 infants still required supplemental oxygen (POD group) and 16 infants were in air (controls). Over the first three weeks, there was a significant rise in the ratio in both groups, indicating a fall in pulmonary arterial pressure. From the third week onwards the ratio was significantly lower in the POD group. There was a significant rise in the ratio from four to 36 weeks after conception in the control group; the POD group showed a tendency towards a fall over the same time period. The requirement for supplemental oxygen almost mirrored the changes in the ratio in both groups but was not significantly different until the fifth week after birth. These data suggest that pulmonary arterial pressure has a significant role in the pathophysiology of prolonged oxygen dependency and may be important in the subsequent morbidity associated with this group of very low birthweight infants.

Pulmonary hypertension in infants with chronic lung disease: non-invasive evaluation and short term effect of oxygen treatment.

A total of 45 examinations on 30 premature infants with chronic lung disease (CLD) of prematurity were made using Doppler echocardiography. Pulmonary systolic time intervals and tricuspid regurgitant velocity were measured to assess the prevalence of pulmonary hypertension and short term responsiveness of the pulmonary circulation to oxygen. Twelve preterm infants matched for gestational age, served as controls. Tricuspid regurgitation (TR) was detected in 14 of the patients. Eleven of those with TR had pulmonary hypertension, of whom eight responded to oxygen treatment. Of the remaining three patients with 'fixed' pulmonary hypertension, one subsequently died. The detection of TR was the basis of the preferred method for measuring pulmonary artery pressure (Ppa) non-invasively, but the degree of correlation between the Ppa estimated from TR and pulmonary systolic time intervals was high (r = -0.84, p = 0.001). In the absence of TR, systolic time intervals are an effective way to monitor pulmonary artery pressure in infants with CLD. Without these measurements, it would have been impossible to predict which subjects had pulmonary hypertension, and which might respond to oxygen treatment.

Simple method to monitor pulmonary artery pressure in infants after cardiac operations

Intraoperative placement of catheters to monitor pulmonary artery pressure and cardiac output by oximetry can easily be accomplished under direct vision. The insertion through a saphenous vein cutdown assures a much safer removal, eliminating the risk of bleeding, tamponade, and catheter entrapment.

Plasma thromboxane and pulmonary artery pressure in neonates treated with extracorporeal membrane oxygenation

To examine whether neonates with persistent pulmonary hypertension are subject to a thromboxane-mediated exacerbation of their pulmonary hypertension during extracorporeal membrane oxygenator therapy (a form of partial cardiopulmonary bypass), we performed serial measurements of plasma thromboxane B2 and pulmonary artery pressure before, during, and after extracorporeal membrane oxygenation. Pulmonary artery pressure was high before extracorporeal membrane oxygenation, did not increase after the start of this therapy, but began to decrease after 48 hours of extracorporeal membrane oxygenation. During the course of extracorporeal membrane oxygenation, mean pulmonary artery pressure decreased by 50% and mean plasma thromboxane B2 levels decreased by 70%. In addition, serial plasma thromboxane B2 levels were significantly correlated with pulmonary artery pressures in individual infants with a primary diagnosis of meconium aspiration (r = 0.965 to 0.723). We speculate that the decrease in pulmonary artery pressure and plasma thromboxane B2 levels over time may reflect resolution of acute lung injury and that thromboxane B2 may play a role in regulating pulmonary artery pressure in infants with meconium aspiration.

Cholelithiasis in premature infants treated with parenteral nutrition and furosemide

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Physiologic factors affecting pulmonary artery pressure in infants with persistent pulmonary hypertension

Indwelling pulmonary artery catheters were used for continuous monitoring of pulmonary artery pressure in ten infants with severe persistent pulmonary hypertention of the newborn. The labile nature of pulmonary artery pressure, with changes up to 50 mm Hg, was documented. Pulmonary artery pressure in the eight infants with suprasystemic pulmonary hypertension was analyzed at the time of maximum decrease in pressure (mean 36.1 mm Hg) and physiologic measurements were compared over an eight-hour period. During the study period when the infants were hyperventilated, as the Paco2 decreased from 48.9 to 28.3 mm Hg (P less than 0.02) the mean pulmonary artery pressure decreased by 36 mm Hg (P less than 0.001) to subsystemic pressure levels, and the mean AadeltaO2 decreased by 146 mm Hg (P less than 0.001). After the decrease in pulmonary artery pressure, patients were mechanically ventilated to maintain Paco2 in the range of 25 to 30 mm Hg until pulmonary hypertension gradually resolved in the six survivors.