The state of point-of-care ultrasonography use and training in neonatal-perinatal medicine and pediatric critical care medicine fellowship programs

OBJECTIVE

The current state of point-of-care ultrasonography (POCUS) use and education in neonatal-perinatal medicine (NPM) and pediatric critical care medicine (PCCM) is unknown. Our aim was to quantify POCUS use, training and perceptions regarding education and barriers among the United States NPM and PCCM fellowship programs.

STUDY DESIGN

A 14-question survey was emailed to the fellowship directors of all the United States NPM and PCCM fellowship programs.

RESULTS

The response rate was 55% (52/95) and 59% (39/66) for NPM and PCCM programs, respectively. Over 90% of respondents in both groups believe that fellows and attendings should receive POCUS training. PCCM programs, compared with NPM, had greater access to POCUS machines (97% vs 63%, P<0.001), and more often used POCUS for diagnoses and management (76% vs 29%, P<0.001) and procedural guidance (95% vs 37%, P<0.001). The most common indications were cardiac/hemodynamics, pulmonary pathology and vascular access in both specialties. PCCM reported more training to fellows (90% vs 29%, P<0.001). Both group perceived lack of time to learn, lack of equipment/funds, liability concerns, lack of personnel to train physicians and cardiology/radiology resistance as significant barriers to POCUS implementation.

CONCLUSIONS

Both NPM and PCCM fellowship programs believe in the benefits of POCUS and that their physicians should receive the necessary training. Compared with PCCM, NPM fellowships programs have less access to POCUS machines and less frequently use POCUS and train their fellows and attendings. There remain significant barriers to utilization of POCUS, especially in NPM.

Prone positioning decreases cardiac output and increases systemic vascular resistance in neonates

OBJECTIVE

To evaluate the cardiovascular response to short-term prone positioning in neonates.

STUDY DESIGN

In this prospective study, we continuously monitored heart rate (HR), stroke volume (SV) and cardiac output (CO) by electrical velocimetry in hemodynamically stable neonates in each of the following positions for 10 min: supine, prone and back-to-supine position. Skin blood flow (SBF) was also continuously assessed on the forehead or foot using Laser Doppler technology. Systemic vascular resistance (SVR) index was calculated as mean blood pressure (BP)/CO. Data were analyzed using repeated measures analysis of variance.

RESULTS

Thirty neonates (gestational age: 35±4 weeks; postmenstrual age: 36±3 weeks) were enrolled. HR did not change in response to positioning. However, in prone position, SV, CO and SBF decreased and SVR index increased from 1.5±0.3 to 1.3±0.3 ml kg(-1) (mean ±s.d., P<0.01), 206±44 to 180±41 ml kg(-1) min(-1) (P<0.01), 0.54±0.30 to 0.44±0.29 perfusion units (P<0.01) and 0.25±0.06 to 0.30±0.07 mm Hg ml(-1) kg(-1) min(-1) (P<0.01), respectively. After placing the infants back-to-supine position, SV, CO, SBF and SVR index returned to baseline. The above pattern of cardiovascular changes was consistent in vast majority of the studied neonates.

CONCLUSIONS

Short-term prone positioning is associated with decreased SV, CO and SBF and increased calculated SVR index.

Does targeted neonatal echocardiography affect hemodynamics and cerebral oxygenation in extremely preterm infants?

OBJECTIVE

To investigate the effect of targeted neonatal echocardiography (TnEcho) on heart rate, arterial oxygen saturation (SPO2), cerebral regional oxygen saturation (CrSO2) and cerebral fractional oxygen extraction (CFOE) in extremely preterm infants during the first 3 postnatal days.

STUDY DESIGN

s a nested study in a prospective observational study, we acquired continuous data on heart rate, SPO2, CrSO2 and CFOE. Data averaged for the duration of TnEcho study were compared with the data collected during a baseline period immediately before the start of echocardiography. The duration of the baseline and study periods was the same. TnEcho evaluation included assessment of preload, afterload, contractility, left and right ventricular output, patent ductus arteriosus and foramen ovale.

RESULT

We analyzed 138 data pairs before and during TnEcho in 22 extremely preterm infants (gestational age 25.9 ± 1.2 weeks; range 23 to 27). There was no significant difference in heart rate between baseline and TnEcho period. There was a statistical, but clinically negligible, difference between baseline and TnEcho in SPO2 (median (quartile) 91.4% (88.9, 94.2) vs 91.3% (88.9, 94), P = 0.048), CrSO2 (76.8% (70.7, 81.5) vs 74.9% (69.5, 80.1), P<0.0001) and CFOE (15.8% (9.8, 23.6) vs 17.5% (11.3, 24.7), P<0.0001). The changes in the parameters monitored were similar in preterm infants who developed peri/intraventricular hemorrhage and in those who did not.

CONCLUSION

Although there were statistically significant changes in SPO2, CrSO2 and CFOE, the alterations were minimal and unlikely of clinical relevance. Thus, cerebral hemodynamics and systemic and cerebral oxygenation are not perturbed during TnEcho and the procedure is well tolerated by the extremely preterm infants during the postnatal transitional period.

A randomized trial of platelet transfusions over 30 vs 120 minutes: is there an effect on post-transfusion platelet counts?

OBJECTIVE

To determine whether platelet infusion time affects platelet counts in thrombocytopenic newborns.

STUDY DESIGN

This was a prospective randomized control study of 43 platelet transfusions given to newborns. Transfusions were randomized to run over either 30 min or 2 h. Platelet counts taken 30 min and 6 h after transfusion were compared using parametric, nonparametric, Pearson's correlation and logistic regression.

RESULT

Changes in platelet counts 30 min and 6 h after transfusion were not different between the groups. Weak but significant negative correlations existed between postmenstrual age and change in platelet count at 30 min (r=-0.33, P=0.04) and 6 h (r=-0.37, P=0.018) after transfusion. There were no differences between the mean blood pressures before and after transfusion in either group.

CONCLUSION

Transfusion duration does not affect post-transfusion platelet counts in newborns. Babies of lower postmenstrual age (PMA) may have better responses to platelet transfusions. Finally, platelet transfusions over both durations are well tolerated in neonates.

Non-invasive measurement of local tissue perfusion and its correlation with hemodynamic indices during the early postnatal period in term neonates

OBJECTIVE

Monitoring the changes in buccal tissue oxygen saturation (StO(2)) may aid in early diagnosis of circulatory compromise. Our objective was to define the normal value of buccal StO(2) and its correlation to the middle cerebral artery (MCA) flow indices and cardiac output in healthy term infants during the first 48 h after birth.

STUDY DESIGN

In this prospective study, we assessed buccal StO(2) by visible light spectroscopy and assessed the left ventricular output (LVO) and MCA flow indices by ultrasound on postnatal days 1 and 2. We enrolled 20 term neonates. The Wilcoxon-matched pairs signed-rank test and Pearson correlation were used to analyze the data.

RESULT

Median (range) buccal StO(2) readings were 68% (62 to 72) on day 1 and 66% (61 to 69) on day 2 (P=0.03). A weak but significant positive correlation was found between buccal StO(2) and LVO (r=0.37, P=0.023). There was no correlation between buccal StO(2) and MCA mean velocity or pulsatility index.

CONCLUSION

Under a physiological state, buccal StO(2) in resting healthy neonates is 61 to 72%, regardless of variability in systemic and cerebral blood flow. Because of its ease of use and non-invasive nature, the use of visible light spectroscopy in conditions with circulatory compromise needs to be further investigated.

Patent ductus arteriosus in the preterm infant: to treat or not to treat?

Pharmacological and/or surgical closure of a hemodynamically significant patent ductus arteriosus (PDA) in the very preterm infant has been the standard of care over the past few decades. However, the rationale for closure of PDA has recently been challenged. In this article, the factors that have fueled the controversy of the approach to the management of PDA and the gap in our knowledge are reviewed in detail. In addition, the pros and cons of the different treatment strategies applied in clinical care are evaluated with a focus on discussing the available evidence in the literature.

Effects of low oxygen saturation limits on the ductus arteriosus in extremely low birth weight infants

OBJECTIVE

Postnatal increase in oxygen promotes constriction of the patent ductus arteriosus (PDA). According to the findings of prospective observational studies, the clinical practice of targeting lower fractional oxygen saturation between 70 and 90% has been associated with a reduced incidence of severe retinopathy of prematurity (ROP) without affecting survival or neurodevelopmental disability at 1 year of age. Our objective was to investigate the impact of the use of a lower oxygen saturation target range on the incidence of early hemodynamically significant PDA (hsPDA) and the need for ductal ligation in extremely low birth weight (ELBW, <1000 g) infants.

STUDY DESIGN

In this retrospective study, we analyzed data from 263 ELBW infants managed 4 years before (episode I: target oxygen saturation 89 to 94%) and after (episode II: target oxygen saturation 83 to 89%) implementation of the use of lower oxygen saturation limits in two neonatal intensive care units. Infants with a birth weight of 1000 to 1500 g were managed with the same oxygen saturation target range (89 to 94%) during both episodes, and they served as controls. Parametric and nonparametric tests were used as appropriate and multivariate logistic regression models were used to correct for confounders.

RESULTS

There was an increase in the incidence of hsPDA (63.2 vs 74.8%, P=0.043), without an increase in the need for surgical ligation (24.2 vs 29.9%, P=0.3) after implementation of the lower oxygen saturation target range policy. After adjusting for confounders, there was an increase in the odds of having an hsPDA (odds ratio (OR) 1.77, 95% confidence interval (CI) (1.03 to 3.06), P=0.04) but the odds for ductal ligation did not change in episode II (OR 1.25, 95% CI (0.70 to 2.25), P=0.4). The incidence of ROP > or = stage III (50.7 vs 15.7%; P<0.0001) and the need for laser ablation (33.8% vs 8.7%; P<0.0001) were significantly reduced. There was no change in the incidence of hsPDA or ductal ligation in the control group.

CONCLUSION

Targeting lower oxygen saturation limits to minimize periods of hyperoxemia in ELBW infants reduced the incidence of severe ROP and the need for laser ablation. The incidence of early hsPDA was increased; however, final closure rate and the incidence of surgical ligation of the ductus arteriosus were not affected.

Artemisinin can inhibit the calmodulin-mediated activation of phosphodiesterase in comparison with Cyclosporin A

Artemisinin and Cyclosporin A were examined for their ability to inhibit the calmodulin-mediated activation of phosphodiesterase, which is based on the hydrolysis of cAMP to AMP by phosphodiesterase in the presence or absence of inhibitors, followed by quantitative analysis using spectrophotometer method. Anti-calmodulin activity of these agents was investigated by spectrofluorometry. Our results indicates that Artemisinin and Cyclosporin A induced some conformational changes on calmodulin and increased the fluorescence emission, but Artemisinin increased fluorescence emission of calmodulin in higher amounts compared with the Cyclosporin A. Kinetic analysis of the Artemisinin-calmodulin and Cyclosporine A-calmodulin interaction showed that these agents competitively inhibited the activation of phosphodiesterase without affecting Vmax. Artemisinin increased Km value in higher amounts compared with the Cyclosporin A. Ki values of Artemisinin and Cyclosporin A were determined as 10 microM and 35 microM, respectively. The DeltaG (H2O), the best parameter for the estimation of macromolecule stability, was determined for calmodulin in the absence and presence of Artemisinin and Cyclosporin A. However, the degree of decrease in DeltaG (H2O) value was as follows: Artemisinin>Cyclosporin A, which means Artemisinin induced more instability in the calmodulin structure.In conclusion, our findings showed a good correlation between the ability of both Artemisinin and Cyclosporin A to block the activation of phosphodiesterase and their ability to bind to the activator and that Artemisinin is a more potent inhibitor of phosphodiesterase compared with Cyclosporin A.

Use of high-frequency jet ventilation in neonates with hypoxemia refractory to high-frequency oscillatory ventilation

OBJECTIVE

To describe the response to high-frequency jet ventilation in infants with hypoxemic respiratory failure unresponsive to high-frequency oscillatory ventilation.

METHODS

This was a retrospective analysis of chart records on demographics, ventilator settings, blood gas analysis and calculated oxygenation index prior to and during the first 7 days of high-frequency jet ventilation in ten consecutive infants.

RESULTS

Before the initiation of high-frequency jet ventilation, the ventilatory mean airway pressure (MAP; cmH2O), fraction of inspired oxygen (FiO2) and oxygenation index on high-frequency oscillatory ventilation were 14.3 +/- 1.3, 0.97 +/- 0.02 and 29 +/- 5, respectively. Three hours after the initiation of high-frequency jet ventilation, the oxygenation index improved to 18 +/- 4 (p < 0.001) and the improvement was sustained during the study period. By 6 h of high-frequency jet ventilation, the FiO2 decreased to 0.62 +/- 0.09 (p < 0.01) and, by 1-3 h of ventilation, the MAP decreased to 10.9 +/- 1.3 (p < 0.01). The improvement in FiO2 persisted for 7 days while, although the MAP remained lower throughout the study, the improvement in MAP failed to reach statistical significance after 72 h. No significant changes in pH, pCO2, or pO2 before or during high-frequency jet ventilation were noted.

CONCLUSION

High-frequency jet ventilation improves hypoxemic respiratory failure unresponsive to high-frequency oscillatory ventilation in infants. These findings suggest that not all high-frequency ventilatory devices yield the same clinical results.