Hemodynamic changes during weaning from nasal continuous positive airway pressure

Continuous Positive Airway Pressure versus Nasal Intermittent Positive Pressure Ventilation in Preterm Neonates: What if Mean Airway Pressures were Equivalent?

Respiratory support for preterm neonates in modern neonatal intensive care units is predominantly with the use of noninvasive interfaces. Continuous positive airway pressure (CPAP) and nasal intermittent positive pressure ventilation (NIPPV) are the prototypical and most commonly utilized forms of noninvasive respiratory support, and each has unique gas flow characteristics. In meta-analyses of clinical trials till date, NIPPV has been shown to likely reduce respiratory failure and need for intubation compared to CPAP. However, a significant limitation of the included studies has been the higher mean airway pressures used during NIPPV. Thus, it is unclear to what extent any benefits seen with NIPPV are due to the cyclic pressure application versus the higher mean airway pressures. In this review, we elaborate on these limitations and summarize the available evidence comparing NIPPV and CPAP at equivalent mean airway pressures. Finally, we call for further studies comparing noninvasive respiratory support modes at equal mean airway pressures. KEY POINTS: · Most current literature on CPAP vs. NIPPV in preterm neonates is confounded by use of higher mean airway pressures during NIPPV.. · In this review, we summarize existing evidence on CPAP vs. NIPPV at equivalent mean airway pressures.. · We call for future research on noninvasive support modes to account for mean airway pressures..

Hemodynamic consequences of respiratory interventions in preterm infants

Advances in perinatal management have led to improvements in survival rates for premature infants. It is known that the transitional period soon after birth, and the subsequent weeks, remain periods of rapid circulatory changes. Preterm infants, especially those born at the limits of viability, are susceptible to hemodynamic effects of routine respiratory care practices. In particular, the immature myocardium and cardiovascular system is developmentally vulnerable. Standard of care (but essential) respiratory interventions, administered as part of neonatal care, may negatively impact heart function and/or pulmonary or systemic hemodynamics. The available evidence regarding the hemodynamic impact of these respiratory practices is not well elucidated. Enhanced diagnostic precision and therapeutic judiciousness are warranted. In this narrative, we outline (1) the vulnerability of preterm infants to hemodynamic disturbances (2) the hemodynamic effects of common respiratory practices; including positive pressure ventilation and surfactant therapy, and (3) identify tools to assess cardiopulmonary interactions and guide management.

Nasal continuous positive airway pressure levels for the prevention of morbidity and mortality in preterm infants

BACKGROUND

Preterm infants are at risk of lung atelectasis due to various anatomical and physiological immaturities, placing them at high risk of respiratory failure and associated harms. Nasal continuous positive airway pressure (CPAP) is a positive pressure applied to the airways via the nares. It helps prevent atelectasis and supports adequate gas exchange in spontaneously breathing infants. Nasal CPAP is used in the care of preterm infants around the world. Despite its common use, the appropriate pressure levels to apply during nasal CPAP use remain uncertain.

OBJECTIVES

To assess the effects of 'low' (≤ 5 cm H₂O) versus 'moderate-high' (> 5 cm H₂O) initial nasal CPAP pressure levels in preterm infants receiving CPAP either: 1) for initial respiratory support after birth and neonatal resuscitation or 2) following mechanical ventilation and endotracheal extubation.

SEARCH METHODS

We ran a comprehensive search on 6 November 2020 in the following databases: CENTRAL via CRS Web and MEDLINE via Ovid. We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We included RCTs, quasi-RCTs, cluster-RCTs and cross-over RCTs randomizing preterm infants of gestational age < 37 weeks or birth weight < 2500 grams within the first 28 days of life to different nasal CPAP levels.

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal to collect and analyze data. We used the GRADE approach to assess the certainty of the evidence for the prespecified primary outcomes.

MAIN RESULTS

Eleven trials met inclusion criteria of the review. Four trials were parallel-group RCTs reporting our prespecified primary or secondary outcomes. Two trials randomized 316 infants to low versus moderate-high nasal CPAP for initial respiratory support, and two trials randomized 117 infants to low versus moderate-high nasal CPAP following endotracheal extubation. The remaining seven studies were cross-over trials reporting short-term physiological outcomes. The most common potential sources of bias were absent or unclear blinding of personnel and assessors and uncertain selective reporting. Nasal CPAP for initial respiratory support after birth and neonatal resuscitation None of the six primary outcomes prespecified for inclusion in the summary of findings was eligible for meta-analysis. No trials reported on moderate-severe neurodevelopmental impairment at 18 to 26 months. The remaining five outcomes were reported in a single trial. On the basis of this trial, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcomes of: death or bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (PMA) (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.56 to 1.85; 1 trial, 271 participants); mortality by hospital discharge (RR 1.04, 95% CI 0.51 to 2.12; 1 trial, 271 participants); BPD at 28 days of age (RR 1.10, 95% CI 0.56 to 2.17; 1 trial, 271 participants); BPD at 36 weeks' PMA (RR 0.80, 95% CI 0.25 to 2.57; 1 trial, 271 participants), and treatment failure or need for mechanical ventilation (RR 1.00, 95% CI 0.63 to 1.57; 1 trial, 271 participants). We assessed the certainty of the evidence as very low for all five outcomes due to risk of bias, a lack of consistency across multiple studies, and imprecise effect estimates. Nasal CPAP following mechanical ventilation and endotracheal extubation One of the six primary outcomes prespecified for inclusion in the summary of findings was eligible for meta-analysis. On the basis of these data, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcome of treatment failure or need for mechanical ventilation (RR 1.52, 95% CI 0.92 to 2.50; 2 trials, 117 participants; I² = 17%; risk difference 0.15, 95% CI -0.02 to 0.32; number needed to treat for an additional beneficial outcome 7, 95% CI -50 to 3). We assessed the certainty of the evidence as very low due to risk of bias, inconsistency across the studies, and imprecise effect estimates. No trials reported on moderate-severe neurodevelopmental impairment at 18 to 26 months or BPD at 28 days of age. The remaining three outcomes were reported in a single trial. On the basis of this trial, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcomes of: death or BPD at 36 weeks' PMA (RR 0.87, 95% CI 0.51 to 1.49; 1 trial, 93 participants); mortality by hospital discharge (RR 2.94, 95% CI 0.12 to 70.30; 1 trial, 93 participants), and BPD at 36 weeks' PMA (RR 0.87, 95% CI 0.51 to 1.49; 1 trial, 93 participants). We assessed the certainty of the evidence as very low for all three outcomes due to risk of bias, a lack of consistency across multiple studies, and imprecise effect estimates.  AUTHORS' CONCLUSIONS: There are insufficient data from randomized trials to guide nasal CPAP level selection in preterm infants, whether provided as initial respiratory support or following extubation from invasive mechanical ventilation. We are uncertain as to whether low or moderate-high nasal CPAP levels improve morbidity and mortality in preterm infants. Well-designed trials evaluating this important aspect of a commonly used neonatal therapy are needed.

Cerebral oxygenation is stable in preterm infants transitioning to heated humidified high-flow nasal cannula therapy

AIM

To assess cerebral oxygenation in premature infants who are transitioning from nasal continuous positive airway pressure (nCPAP) to heated humidified high-flow nasal cannula therapy (HFNC).

METHODS

A prospective observational study done in a single-centre neonatal intensive care unit (NICU). Regional cerebral oxygen saturations (RcSO₂ ) were measured using frequency-domain near-infrared spectroscopy (FD-NIRS) in very low birthweight (VLBW) premature infants born at <32 weeks transitioning from nCPAP to HFNC.

RESULTS

Median gestational age was 27 weeks and median birthweight was 924 g. Recordings were performed at a median gestational age of 30 weeks and a median postnatal age of 10 days. Median weight at study entry was 1111 g. Cerebral oxygenation was not significantly different in infants transitioning from nCPAP to HFNC (66% vs 66%).

CONCLUSION

No difference in cerebral oxygenation in premature infants transitioning from nCPAP to HFNC was observed. This finding is reassuring and further supports the use of HFNC in preterm infants.

High CPAP vs. NIPPV in preterm neonates - A physiological cross-over study

OBJECTIVE

To evaluate the physiological impact of high CPAP (≥9 cmH2O) vs. NIPPV at equivalent mean airway pressures.

STUDY DESIGN

In this cross-over study, preterm neonates on high CPAP or NIPPV were placed on the alternate mode. After 30 min, left and right ventricular cardiac output and work of breathing indices were assessed, following which patients were placed back on the original mode and a similar procedure ensued.

RESULTS

Fifteen infants with mean (SD) postmenstrual age 32.7 (3.0) weeks, and weight 1569 (564) grams were included. No differences in LVO [320 (63) vs. 331 (86) mL/kg/min, P = 0.46] or RVO [420 (135) vs. 437 (141) mL/kg/min, P = 0.19] were noted during high CPAP vs. NIPPV, along with no differences in work of breathing indices.

CONCLUSION

High CPAP pressures did not adversely impact cardiac output or work of breathing compared to NIPPV at equivalent mean airway pressure.

Bubble Nasal Continuous Positive Airway Pressure (bNCPAP): An Effective Low-Cost Intervention for Resource-Constrained Settings

Preterm birth complications are responsible for almost one-third of the global neonatal mortality burden, and respiratory distress syndrome remains the single most common cause of these preventable deaths. Since its inception, almost half a century ago, nasal continuous positive airway pressure (NCPAP) has evolved to become the primary modality for neonatal respiratory care in both the developed and developing world. Although evidence has demonstrated the effectiveness of low-cost bubble NCPAP in reducing newborn mortality, its widespread use is yet to be seen in resource-constrained settings. Moreover, many tertiary hospitals in developing countries still utilise an inexpensive locally assembled bNCPAP system of unknown efficacy and safety. This review provides a brief overview of the history, physiological benefits, indications, contraindications, and complications of bNCPAP. Evidence regarding the effectiveness of low-cost bNCPAP in the neonatal intensive care unit is also summarised. The article further details a locally assembled bNCPAP system used in resource-constrained settings and highlights the care package for neonates receiving bNCPAP, failure criteria, and strategies for weaning.

Superior vena cava flow: Role, assessment and controversies in the management of perinatal perfusion

The superior vena cava (SVC) is a large vein responsible for the venous return of blood from structures located superior to the diaphragm. The flow in the SVC can be assessed with Doppler ultrasound and can be used as a proxy for cerebral perfusion. Early clinical research studies showed that low SVC flow, particularly if for a prolonged period, was associated with short term morbidity such as intraventricular hemorrhage, mortality, and poorer neurodevelopmental outcomes. However, these findings have not been consistently reported in more recent studies, and the role of SVC flow in early management and as a predictor of poor long-term neurodevelopment has been questioned. This paper provides an overview of SVC assessment, the expected range of findings, and reviews the role of SVC flow as a diagnostic and monitoring tool for the assessment of perinatal perfusion.

High-CPAP Does Not Impede Cardiovascular Changes at Birth in Preterm Sheep

Objective: Continuous positive airway pressures (CPAP) used to assist preterm infants at birth are limited to 4-8 cmH₂O due to concerns that high-CPAP may cause pulmonary overexpansion and adversely affect the cardiovascular system. We investigated the effects of high-CPAP on pulmonary (PBF) and cerebral (CBF) blood flows and jugular vein pressure (JVP) after birth in preterm lambs. Methods: Preterm lambs instrumented with flow probes and catheters were delivered at 133/146 days gestation. Lambs received low-CPAP (LCPAP: 5 cmH₂O), high-CPAP (HCPAP: 15 cmH₂O) or dynamic HCPAP (15 decreasing to 8 cmH₂O at ~2 cmH₂O/min) for up to 30 min after birth. Results: Mean PBF was lower in the LCPAP [median (Q1-Q3); 202 (48-277) mL/min, p = 0.002] compared to HCPAP [315 (221-365) mL/min] and dynamic HCPAP [327 (269-376) mL/min] lambs. CBF was similar in LCPAP [65 (37-78) mL/min], HCPAP [73 (41-106) mL/min], and dynamic HCPAP [66 (52-81) mL/min, p = 0.174] lambs. JVP was similar at CPAPs of 5 [8.0 (5.1-12.4) mmHg], 8 [9.4 (5.3-13.4) mmHg], and 15 cmH₂O [8.6 (6.9-10.5) mmHg, p = 0.909]. Heart rate was lower in the LCPAP [134 (101-174) bpm; p = 0.028] compared to the HCPAP [173 (139-205)] and dynamic HCPAP [188 (161-207) bpm] groups. Ventilation or additional caffeine was required in 5/6 LCPAP, 1/6 HCPAP, and 5/7 dynamic HCPAP lambs (p = 0.082), whereas 3/6 LCPAP, but no HCPAP lambs required intubation (p = 0.041), and 1/6 LCPAP, but no HCPAP lambs developed a pneumothorax (p = 0.632). Conclusion: High-CPAP did not impede the increase in PBF at birth and supported preterm lambs without affecting CBF and JVP.

Effects of Nasal Continuous Positive Airway Pressure on Cerebral Hemodynamics in Preterm Infants

Background: To evaluate the effects of pressure levels on cerebral hemodynamics in premature infants receiving nasal continuous positive airway pressure (nCPAP) during the first 3 days of life. Methods: Forty-four preterm infants treated with nCPAP were divided into two groups: very preterm infants [gestational age 1 (GA1), GA < 32 weeks, n = 24] and moderate/late preterm infants (GA2 group, GA 32-37 weeks, n = 20). During monitoring, pressure levels were set at 4 → 6 → 8 → 4 cmH₂O, and cerebral hemodynamics was assessed by near-infrared spectroscopy (NIRS). Vital signs, peripheral oxygen saturation (SpO₂) and transcutaneous carbon dioxide pressure (TcPCO₂) were simultaneously recorded. Results: Pressures of 4-8 cmH₂O had no significant influence on cerebral hemodynamics, TcPCO₂, SpO₂ or other vital signs. The tissue oxygenation index (TOI), the difference between oxygenated hemoglobin (ΔHbO₂) and deoxygenated hemoglobin (ΔHHb) (ΔHbD), and cerebral blood volume (ΔCBV) were all significantly positively correlated with gestational and post-natal age, with fluctuations being greater in the GA1 group. ΔHbD and ΔCBV were also significantly positively correlated with TcPCO₂. Conclusions: No significant differences were observed in cerebral hemodynamics when the nCPAP pressure was set to 4-8 cmH₂O.

Oxygen saturation histograms predict nasal continuous positive airway pressure-weaning success in preterm infants

BACKGROUND

Continuous positive airway pressure (CPAP) is widely used in preterm infants. Identification of readiness for weaning from CPAP can balance benefits with risks of CPAP exposure. We tested the hypothesis that preterm infants that successfully transition off CPAP have higher oxygen saturations prior to weaning compared with infants who fail weaning from CPAP.

METHODS

This was a single-center-matched case-control study in infants ≤30 weeks' gestation receiving ≤30% FiO₂ weaned off CPAP during the first postnatal week. Cases were infants placed back on CPAP within 7 days of being taken off CPAP, whereas control infants remained off CPAP for 7 consecutive days following CPAP discontinuation. Infants were matched on gestational age at birth (±10 days). Prospectively collected histograms detailing the distribution of oxygen saturations prior to CPAP discontinuation were compared between cases and controls.

RESULTS

Over a 12-month monitoring period, 36 infants met inclusion criteria. Baseline characteristics, morbidities, and clinical variables did not differ between cases and controls. Controls achieved oxygen saturations of 95-97 and 97-100% for longer duration compared to cases (p < 0.05).

CONCLUSIONS

In preterm infants with RDS receiving CPAP and ≤30% FiO₂, infants with higher oxygen saturations had greater success in transitioning off CPAP.

Hemodynamic management in chronically ventilated infants

Positive pressure ventilation can significantly alter hemodynamics. The reduction in systemic venous return and increase in right ventricular afterload in response to an inappropriately high mean airway pressure can decrease pulmonary blood flow and compromise systemic perfusion as a result. In addition to ventilator parameters, the degree of hemodynamic effects depends on the baseline cardiac function and lung compliance. Furthermore, the chronically ventilated infants often have a multitude of comorbidities which may also impact hemodynamics. These include pulmonary and systemic hypertension which can lead to myocardial dysfunction as a result of the increase in the right and left ventricular afterload, respectively. In this section, we aim to outline the hemodynamic changes associated with chronic lung disease and mechanical ventilation and discuss management options.

High continuous positive airway pressure in neonates: A physiological study

OBJECTIVE

We sought to evaluate physiological cardiorespiratory implications of high pressures (>8 cmH₂ O) on continuous positive airway pressure (CPAP) in preterm neonates.

METHODS

Fifteen preterm neonates at postmenstrual age ≥32 weeks on CPAP 5 cmH₂ O were enrolled. Pressures were increased by 2 cmH ₂ O increments until 13 cmH ₂ O. At each increment, cardiac output, electrical diaphragmatic (Edi) activity, and clinical cardiorespiratory parameters were measured. Predefined cut-off values for changes in cardiorespiratory parameters were used as termination criteria. Data, presented as mean (SD), were compared using repeated measures analysis of variance.

RESULTS

The mean GA, age at study, and weight of subjects were 27.4 (2.6) weeks, 58.5 (35.5) days, and 2.3 (0.6) kg, respectively. The median (IQR) time at each CPAP increment was 10 (5, 20) min. Cardiac output (mL/kg/min) at 5, 7, 9, 11, and 13 cmH ₂ O were not different at 295 (75), 290 (66), 281 (69), 286 (73), and 292 (58), respectively (P = 0.99). Edi values demonstrated a trend towards decline at 9 cmH ₂ O before rising again. No other cardiorespiratory parameter was different across CPAP levels; no subject met termination criteria.

CONCLUSION

High CPAP levels were well tolerated for short durations. Further physiological and clinical research is required on safety/efficacy in neonates with more severe lung disease, as well as its impact over longer durations.

Acute hemodynamic effects of methylxanthine therapy in preterm neonates: Effect of variations in subgroups

BACKGROUND

Methylxanthines have cardiac stimulant effects. The current study aimed to compare acute hemodynamic changes between caffeine and aminophylline in ≤34 weeks' preterm neonates.

METHODS

The study was performed using information on echocardiography measurements from preterm neonates recruited for apnea of prematurity (75 of 240) and preventing extubation failure (113 of 156) studies. The neonates were randomized either to the caffeine or aminophylline groups. Neonates with no maintenance followed by loading doses with both the methylxanthines (caffeine and aminophylline) and incomplete echocardiography examination were excluded.

RESULTS

Cardiac parameters were found to be similar between groups. The heart rate was higher among the aminophylline-treated neonates (p < 0.001) than among the caffeine-treated ones. End-systolic volume was higher among both caffeine- (p < 0.001) and aminophylline-treated neonates (p = 0.001) when compared with pretreatment values. End-diastolic volume was statistically higher in both groups' neonates (p = 0.01). The odds of increase in cardiac output was higher; however, increase in ejection fraction was less in caffeine-treated small-for-gestation-age neonates.

CONCLUSION

Caffeine has similar effects on cardiac parameters as aminophylline; however, caffeine-treated small-for-gestation stratification gave rise to significant cardiac variations.

The Effect of Continuous Positive Airway Pressure on Cerebral and Splanchnic Oxygenation in Preterm Infants

BACKGROUND

Despite the known clinical benefits of continuous positive airway pressure (CPAP) to support preterm infants breathing, there are limited studies that have examined its effect on regional oxygenation.

OBJECTIVES

This study aimed to investigate how the application of CPAP affects cerebral and splanchnic tissue oxygenation in preterm infants.

METHODS

A pilot observational study was conducted in infants using near-infrared spectroscopy while off CPAP and on CPAP. Regional cerebral and splanchnic saturations and variability (coefficient of variability; CV) were evaluated.

RESULTS

Twenty-six infants (25-37 weeks gestational age at birth) were studied. The mean cerebral oxygenation did not differ with the application of CPAP (80 ± 4.2% without CPAP; 80 ± 1.9% with CPAP), but variability around the mean was less with CPAP (CV 5 vs. 2%, respectively). Mean cerebral fractional oxygen extraction (FOE) increased with CPAP from 0.13 ± 0.06 to 0.17 ± 0.04% (p = 0.002). Splanchnic oxygenation increased significantly from 66 ± 11.6 to 75 ± 9.1% with CPAP (p < 0.001) and also became more stable (CV 13 vs. 7%, respectively). Splanchnic FOE decreased with CPAP from 0.28 ± 0.13 to 0.22 ± 0.10% (p = 0.002).

CONCLUSION

The application of CPAP did not affect mean cerebral oxygenation in this group of preterm and term infants; however, it led to a significant increase in splanchnic oxygenation. These findings highlight the important role that respiratory support may play in maintaining adequate and stable oxygen delivery to vital organs.

Pleth variability index and respiratory system compliance to direct PEEP settings in mechanically ventilated patients, an exploratory study

OBJECTIVES

To analyze the ability of pleth variability index (PVI) and respiratory system compliance (RSC) on evaluating the hemodynamic and respiratory effects of positive end expiratory pressure (PEEP), then to direct PEEP settings in mechanically ventilated critical patients.

METHODS

We studied 22 mechanically ventilated critical patients in the intensive care unit. Patients were monitored with classical monitor and a pulse co-oximeter, with pulse sensors attached to patients' index fingers. Hemodynamic data [heart rate (HR), perfusion index (PI), PVI, central venous pressure (CVP), mean arterial pressure (MAP), peripheral blood oxygen saturation (SPO2), peripheral blood oxygen content (SPOC) and peripheral blood hemoglobin (SPHB)] as well as the respiratory data [respiratory rate (RR), tidal volume (VT), RSC and controlled airway pressure] were recorded for 15 min each at 3 different levels of PEEP (0, 5 and 10 cmH2O).

RESULTS

Different levels of PEEP (0, 5 and 10 cmH2O) had no obvious effect on RR, HR, MAP, SPO2 and SPOC. However, 10 cmH2O PEEP induced significant hemodynamic disturbances, including decreases of PI, and increases of both PVI and CVP. Meanwhile, 5 cmH2O PEEP induced no significant changes on hemodynamics such as CVP, PI and PVI, but improved the RSC.

CONCLUSIONS

RSC and PVI may be useful in detecting the hemodynamic and respiratory effects of PEEP, thus may help clinicians individualize PEEP settings in mechanically ventilated patients.

Duration of continuous positive airway pressure in premature infants

Continuous positive airway pressure (CPAP) has been used for respiratory support in premature infants for more than 40 years and is now a cornerstone of modern neonatal care. Clinical research on CPAP has primarily focused on understanding which devices and pressure sources best implement this therapy. In contrast, less research has examined the optimal duration over which CPAP is administered. We review this aspect of CPAP therapy.

Physiology of non-invasive respiratory support

Non-invasive ventilation (NIV) is used in neonates to treat extrathoracic and intrathoracic airway obstruction, parenchymal lung disease and disorders of control of breathing. Avoidance of airway intubation is associated with a reduction in the incidence of chronic lung disease among preterm infants with respiratory distress syndrome. Use of nasal continuous positive airway pressure (nCPAP) may help establish and maintain functional residual capacity (FRC), decrease respiratory work, and improve gas exchange. Other modes of non-invasive ventilation, which include heated humidified high-flow nasal cannula therapy (HHHFNC), nasal intermittent mandatory ventilation (NIMV), non-invasive pressure support ventilation (NI-PSV), and bi-level CPAP (SiPAP™), have also been shown to provide additional benefit in improving breathing patterns, reducing work of breathing, and increasing gas exchange when compared with nCPAP. Newer modes, such as neurally adjusted ventilatory assist (NAVA), hold the promise of improving patient-ventilator synchrony and so might ultimately improve outcomes for preterm infants with respiratory distress.

Hemodynamic Effects of Nasal Intermittent Positive Pressure Ventilation in Preterm Infants

Nasal intermittent positive pressure ventilation (NIPPV) and nasal continuous positive airway pressure (NCPAP) have proven to be effective modes of noninvasive respiratory support in preterm infants. Although they are increasingly used in neonatal intensive care, their hemodynamic consequences have not been fully evaluated. The aim of this study was to investigate the hemodynamic changes between NIPPV and NCPAP in preterm infants.This prospective observational study enrolled clinically stable preterm infants requiring respiratory support received NCPAP and nonsynchronized NIPPV at 40/minute for 30 minutes each, in random order. Cardiac function and cerebral hemodynamics were assessed by ultrasonography after each study period. The patients continued the study ventilation during measurements.Twenty infants with a mean gestational age of 27 weeks (range, 25-32 weeks) and birth weight of 974 g were examined at a median postnatal age of 20 days (range, 9-28 days). There were no significant differences between the NCPAP and NIPPV groups in right (302 vs 292 mL/kg/min, respectively) and left ventricular output (310 vs 319 mL/kg/min, respectively), superior vena cava flow (103 vs 111 mL/kg/min, respectively), or anterior cerebral artery flow velocity.NIPPV did not have a significant effect on the hemodynamics of stable preterm infants. Future studies assessing the effect of NIPPV on circulation should focus on less stable and very preterm infants.

Effect of Nasal Continuous Positive Airway Pressure (NCPAP) Cycling and Continuous NCPAP on Successful Weaning: A Randomized Controlled Trial

OBJECTIVE

To compare the effectiveness of nasal continuous positive airway pressure (NCPAP) cycling with continuous NCPAP in the successful weaning of preterm infants of 25(0)-28(6) wk gestation to nasal prongs.

METHODS

A total of 30 infants with a gestational age (GA) of 25(0)-28(6) wk, ventilated for respiratory distress syndrome (RDS) and extubated to NCPAP were eligible for the study. They were randomized to NCPAP cycling [Group A: cycling between NCPAP of 4 cm and 1 liter per minute (LPM) of nasal prongs] or to continuous NCPAP at 4 cm of H2O (Group B). Primary outcome was successful weaning off NCPAP to nasal prongs at the end of 72 h of the intervention and remaining off NCPAP for the next 72 h.

RESULTS

The demographic characteristics were similar in both the groups. Infants were randomized to Group A (n = 13) and Group B (n = 17). The primary outcome was not significantly different between the groups (successful weaning to nasal prongs: 31 vs. 41 %; p 0.71).

CONCLUSIONS

In this pilot, feasibility study there were no differences in the rates of successful weaning of NCPAP to nasal prongs using either cycling NCPAP or continuous NCPAP in preterm infants. A need exists for a large randomized controlled trial (RCT) to determine the role of cycling NCPAP on neonatal outcomes.

Weaning preterm infants from continuous positive airway pressure: evidence for best practice

BACKGROUND

Nasal continuous positive airway pressure (NCPAP) is frequently used in preterm infants. However, there is no consensus on when and how to wean them from NCPAP.

DATA SOURCES

Based on recent publications, we have reviewed the criteria of readiness-to-wean and factors affecting weaning success. A special focus is placed on the methods of weaning from NCPAP in preterm infants.

RESULTS

Practical points of when and how to wean from NCPAP in preterm infants are explained. Preterm infants are ready to be weaned from NCPAP when they are stable on a low NCPAP pressure with no (or minimal) oxygen requirement. Methods used to wean from NCPAP include: sudden weaning of NCPAP, gradual decrease of NCPAP pressure, graded-timeoff NCPAP (cycling), weaning to high or low flow nasal cannula, and a combination of these methods. The best strategy for weaning is yet to be determined. Cyclingoff NCPAP increases the duration of NCPAP and length of hospital stay without beneficial effect on success of weaning. Gradual decrease of NCPAP pressure is more physiological and better tolerated than cycling-off NCPAP.

CONCLUSION

Further studies are needed to reach a consensus regarding the optimal timing and the best method for weaning from NCPAP in preterm infants.

Cerebral oxygenation with different nasal continuous positive airway pressure levels in preterm infants

OBJECTIVES

This study evaluates the effect of varying nasal continuous positive airway pressure (NCPAP) level on cerebral blood flow (CBF) and oxygenation in preterm infants.

METHODS

Oxy-haemoglobin (HbO2) and total haemoglobin (HbTot), as CBF estimates, and the ratio between HbO2 and HbTot (HbO2/HbTot), as cerebral oxygenation estimate, were assessed by near-infrared spectroscopy in 26 stable preterm newborns at a postmenstrual age between 26 and 33 weeks. Baseline HbO2, HbTot and HbO2/HbTot values were initially collected with NCPAP at 5 cm H2O and then compared with values obtained with NCPAP levels at both 3 and 8 cm H2O.

RESULTS

Compared with 5 cm H2O, cerebral HbO2, HbTot and HbO2/HbTot remained unchanged both after increasing (to 8 cm H2O) and decreasing (to 3 cm H2O) the NCPAP level. This result was observed both in regional areas (24 sites) and in the overall monitored area (frontal and parietal cortex). Compared with 8 cm H2O, peripheral oxygen saturation significantly decreased at 3 cm H2O (p=0.021). Heart rate did not change.

CONCLUSIONS

No differences in CBF and cerebral oxygenation were observed with NCPAP levels in the range 3-8 cm H2O despite a decrease in peripheral oxygenation with 3 cm H2O.

Hemodynamic effects of nasal continuous positive airway pressure in preterm infants with evolving chronic lung disease, a crossover randomized trial

Previous studies suggest that high airway pressure may compromise cardiac output. We investigated the effect of 3 nasal continuous positive airway pressure levels on cardiac output in preterm infants with evolving chronic lung disease. We found that brief changes in continuous positive airway pressure did not affect cardiac output.

Bi-level CPAP does not change central blood flow in preterm infants with respiratory distress syndrome

Background

Current literature provides limited data on the hemodynamic changes that may occur during bi-level continuous positive airway pressure (CPAP) support in preterm infants. However, the application of a positive end-expiratory pressure may be transmitted to the heart and the great vessels resulting in changes of central blood flow.

Objective

To assess changes in central blood flow in infants with respiratory distress syndrome (RDS) during bi-level CPAP support.

Design

A prospective study was performed in a cohort of 18 Very-Low-Birth-Weight Infants who were put on nasal CPAP support (4–5 cmH₂O) because they developed RDS within the first 24–72 hours of life. Each subject was switched to bi-level CPAP support (Phigh 8 cmH₂O, Plow 4–5 cmH₂O, Thigh 0.5-0.6 seconds, 20 breaths/min) for an hour. An echocardiographic study and a capillary gas analysis were performed before and after the change of respiratory support.

Results

No differences between n-CPAP and bi-level CPAP in left ventricular output (LVO, 222.17 ± 81.4 vs 211.4 ± 75.3 ml/kg/min), right ventricular output (RVO, 287.8 ± 96 vs 283.4 ± 87.4 ml/kg/min) and superior vena cava flow (SVC, 135.38 ± 47.8 vs 137.48 ± 46.6 ml/kg/min) were observed. The hemodynamic characteristics of the ductus arteriosus were similar. A significant decrease in pCO₂ levels after bi-level CPAP ventilation was observed; pCO₂ variations did not correlate with modifications of central blood flow (LVO: ρ = 0.11, p = 0,657; RVO: ρ = −0.307, p = 0.216; SVC: ρ = −0.13, p = 0.197).

Conclusions

Central blood flow doesn’t change during bi-level CPAP support, which could become a hemodinamically safe tool for the treatment of RDS in preterm infants.

The effects of nasal continuous positive airway pressure on cardiac function in premature infants with minimal lung disease: a crossover randomized trial

OBJECTIVE

To assess the effects of different nasal continuous positive airway pressure (nCPAP) pressures on cardiac performance in preterm infants with minimal lung disease, we conducted a randomized, blinded crossover study.

STUDY DESIGN

We studied infants between 28 and 34 weeks' corrected gestational age, treated with nCPAP of 5 cm H2O, in air. Infants with significant cardiac shunts were excluded. Infants were randomly assigned to nCPAP levels of 4, 6, and 8 cm H2O for 15 minutes each. Right and left ventricular outputs and left pulmonary artery and superior vena cava flows were measured 15 minutes after each change.

RESULTS

Thirty-four infants born at a mean gestational age of 29 weeks with a birth weight of 1.3 kg were studied. There were no significant differences in right and left ventricular outputs and left pulmonary artery and superior vena cava flows at different levels of nCPAP.

CONCLUSION

We investigated the effect of increasing nCPAP levels on cardiac output. We conclude that nCPAP levels between 4 and 8 cm H2O did not have an effect on cardiac output in stable preterm infants with minimal lung disease.

Pilot observational study on haemodynamic changes after surfactant administration in preterm newborns with respiratory distress syndrome

Background

Surfactant treatment reduces respiratory morbidity and mortality in preterm infants. Data on its haemodynamic consequences are conflicting. The aim was to characterise the haemodynamic effects of surfactant treatment on cardiac function in preterm newborns with respiratory distress syndrome (RDS).

Methods

Preterm infants (gestational age <34 weeks, birth weight <2000 g) with RDS, who received surfactant within 72 hours of life, were recruited.

Echocardiography was performed before surfactant, and 2 and 24 hours after. Left and right ventricular peak systolic, early diastolic and late diastolic myocardial velocities were measured using Tissue Doppler Imaging (TDI), while characteristics of the ductus arteriosus, pulmonary artery pressure, right ventricular (RVO) and left ventricular output were measured by standard echocardiography. Tricuspidal Annular Plane Systolic Excursion (TAPSE) was measured on the free wall of the tricuspid annulus.

Results

Fourteen patients were studied. Surfactant was associated with a decrease in pulmonary pressure and an increase in RVO. The improvement of right ventricular function was also confirmed by a significant increase in right peak systolic velocity and in TAPSE. Left ventricular velocities did not change significantly after surfactant.

Conclusions

Surfactant administration in preterm infants with RDS did not impair myocardial contractility and was followed by increased RVO, in agreement with other parameters of right ventricular function. TDI and TAPSE appeared to be reliable and feasible in this population. The addition of TDI and TAPSE to standard neonatal echocardiography may provide additional information about cardiac function.

Efeitos hemodinâmicos da ventilação não invasiva com máscara facial em prematuros

Recém-nascidos prematuros apresentam desvantagem mecânica dos músculos inspiratórios, predisposição à fadiga muscular e colapso das vias aéreas. A ventilação não invasiva (VNI) é a terapia de expansão de escolha para essa população. No entanto, não existem estudos sobre a avaliação do risco-benefício de sua aplicação por máscara facial em neonatos durante a fisioterapia respiratória. O objetivo desse estudo foi avaliar variáveis hemodinâmicas em recém-nascidos prematuros (RNPT) submetidos à utilização da VNI por máscara facial para terapia de expansão pulmonar. Trata-se de um estudo quase experimental do tipo antes e depois, em que foram avaliados 14 RNPT, com idade gestacional (IG) <37 semanas, de ambos os sexos, com indicação de terapia de expansão pulmonar. Os RNPT foram avaliados antes, durante, imediatamente após, 30 e 60 minutos após a aplicação da VNI, tendo sido coletados frequência cardíaca (FC), pressão arterial (PA), pressão arterial média (PAM) e saturação periférica de oxigênio (SpO2). Foi observado um aumento significativo da SpO2 quando comparados os momentos antes e durante a aplicação da VNI (96,95 [94,98; 99,48] versus 99,15 [97,98; 100,0], p<0,05). Não foram observadas variações significativas da FC e PAM decorrentes da VNI por máscara facial. Com os presentes resultados, sugere-se que a VNI por máscara facial é benéfica para o recém-nascido, sem promover instabilidade hemodinâmica.

The NOFLO trial: low-flow nasal prongs therapy in weaning nasal continuous positive airway pressure in preterm infants

OBJECTIVE

To determine if low-flow nasal prongs therapy with room air, compared with no treatment, facilitates weaning from nasal continuous positive airway pressure (NCPAP) in very low birth weight (VLBW, birth weight <1500 g) infants.

STUDY DESIGN

VLBW infants who received respiratory support for ≥ 48 hours and who were stable on NCPAP for 24 hours were eligible for inclusion in this multicenter, randomized controlled trial. On stopping NCPAP, infants were randomized to receive 1 L/min air via nasal prongs or to spontaneous breathing in room air. The primary outcome measure was failure to wean. Secondary outcome measures included length of time to failure and change in heart rate, respiratory rate, oxygen saturation, and respiratory distress score.

RESULTS

Seventy-eight infants were randomized: 39 to nasal prongs and 39 to spontaneous breathing. The groups were similar at birth and at randomization. Sixteen infants (41%) in the nasal prongs group failed the weaning process compared with 12 infants (31%) in the spontaneous breathing group (OR 1.57, 95% CI 0.56 to 4.43, P = .48). There were no significant differences between the groups in secondary outcomes.

CONCLUSIONS

In this study, we did not demonstrate a benefit of low-flow room air via nasal prongs to wean VLBW infants from NCPAP.

Right ventricular performance in preterm and term neonates: reference values of the tricuspid annular peak systolic velocity measured by tissue Doppler imaging

BACKGROUND

The tricuspid annular peak systolic velocity (S') is an echocardiographic measurement to assess systolic right ventricular function in adults and children.

OBJECTIVE

We determined growth and birth weight-related changes of S' to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 290 preterm and term neonates (gestational age 26 + 0 to 40 + 6 weeks of gestation; birth weight 660-4,460 g). A correlation of S' values with established tricuspid annular plane systolic excursion (TAPSE) values was performed.

RESULTS

The S' ranged from a mean of 4.5 cm/s (Z-score ± 2 SD: 3.6-5.5 cm/s) in preterm neonates in week 26(0-6) of gestation to 7.8 cm/s (Z-score ± 2 SD: 5.5-10.1 cm/s) in term neonates in week 40(0-6) of gestation. The S' values increased from 26 to 40 weeks of gestation. S' and week of gestation are strongly correlated: Pearson's correlation coefficient was 0.66 for week of gestation - S' (p < 0.001). A significant correlation was found between S' and TAPSE values (r = 0.67; p < 0.001).

CONCLUSION

Z-scores of S' values were calculated and percentile charts were established to serve as reference data for preterm and term neonates with structurally normal hearts.

Current methods of non-invasive ventilatory support for neonates

Non-invasive ventilatory support can reduce the adverse effects associated with intubation and mechanical ventilation, such as bronchopulmonary dysplasia, sepsis, and trauma to the upper airways. In the last 4 decades, nasal continuous positive airway pressure (CPAP) has been used to wean preterm infants off mechanical ventilation and, more recently, as a primary mode of respiratory support for preterm infants with respiratory insufficiency. Moreover, new methods of respiratory support have been developed, and the devices used to provide non-invasive ventilation (NIV) have improved technically. Use of NIV is increasing, and a variety of equipment is available in different clinical settings. There is evidence that NIV improves gas exchange and reduces extubation failure after mechanical ventilation in infants. However, more research is needed to identify the most suitable devices for particular conditions; the NIV settings that should be used; and whether to employ synchronized or non-synchronized NIV. Furthermore, the optimal treatment strategy and the best time for initiation of NIV remain to be identified. This article provides an overview of the use of non-invasive ventilation (NIV) in newborn infants, and the clinical applications of NIV.

Systolic right ventricular function in preterm and term neonates: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 258 patients and calculation of Z-score values

BACKGROUND

The tricuspid annular plane systolic excursion (TAPSE) is an echocardiographic measurement to assess right ventricular systolic function in adults and children.

OBJECTIVE

We determined growth- and birth weight-related changes of TAPSE to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 258 preterm and term neonates (age: 25+0 to 40+6 weeks of gestation, birth weight: 530-4200 g).

RESULTS

The TAPSE ranged from a mean of 0.44 cm (Z-score ±2: 0.30-0.59 cm) in preterm neonates in the 26th week of gestation to 1.03 cm (Z-score ±2: 0.85-1.21 cm) in term neonates in the 41st week of gestation. The TAPSE values increased in a linear way from the 26th to 41st week of gestation. TAPSE, week of gestation and weight are strongly correlated: Pearson's correlation coefficient was 0.93 for week of gestation - TAPSE (p < 0.001), 0.93 for week of gestation - birth weight (p < 0.001), and 0.89 for birth weight - TAPSE (p < 0.001). There was no statistically significant difference of normal TAPSE values between female and male patients (p = 0.987).

CONCLUSION

Z-scores of TAPSE values were calculated and percentile charts were established to serve as reference data for ready application in preterm and term neonates with structurally normal hearts and with congenital heart disease in the future.

Systemic and cerebral hemodynamics during the transitional period after premature birth

Little is known about the effect on clinically relevant outcomes of the complex hemodynamic changes occurring during adaptation to extrauterine life in preterm neonates, particularly in very low birth weight neonates. As cardiovascular adaptation in this extremely vulnerable patient population is complicated by immaturity of all organ systems, especially that of the cardiorespiratory, central nervous, and endocrine systems, maladaptation has been suspected, but not necessarily proven, to contribute to mortality and long-term morbidities. This article describes recent advances in the understanding of hemodynamic changes in very low birth weight neonates during postnatal transition, and reviews the complex and developmentally regulated interaction between systemic and cerebral hemodynamics and the effect of this interaction on clinically relevant outcomes.

Early nasal continuous positive airway pressure and necrotizing enterocolitis in preterm infants

BACKGROUND

The use of early nasal continuous positive airway pressure (ENCPAP) as the mode of initial respiratory support for very low birth weight (VLBW) infants has been increasing. The impact of CPAP and oxygen on gut mucosa and perfusion in premature infants is not known. The relation between ENCPAP and necrotizing enterocolitis (NEC) has not been adequately addressed.

OBJECTIVE

To evaluate if the use of an individualized respiratory management strategy encouraging the use of ENCPAP is associated with an increased risk of NEC, and to determine risk factors for NEC in premature infants supported by CPAP.

METHODS

A retrospective analysis was conducted on VLBW infants (birth weight < 1500 g) managed at 2 institutions that use an ENCPAP respiratory management strategy for premature infants. Data on the use of oxygen and mode of ventilatory support were collected during the first 3 days of life. Diagnosis of NEC was used as the dependent variable in a logistic regression model. Birth weight, gender, prenatal steroid use, mode of respiratory support (CPAP versus ventilator) and fraction of inspired oxygen, umbilical artery catheter placement, partial pressure of oxygen, patent ductus arteriosus, early sepsis, hospital, and delivery room management (ENCPAP versus initial intubation) were controlled for in the model.

RESULTS

Data on 343 premature infants were collected for this study. Mean birth weight was 999 +/- 289 g and gestational age was 28 +/- 2.6 weeks. The majority of patients were managed with ENCPAP, with only 13% of patients intubated in the delivery room. The overall incidence of NEC was 7% (n = 24). The exposure to ENCPAP did not increase the risk for NEC compared with the use of a ventilator. CONCLUSIONS. The risk of NEC in VLBW premature infants was not increased by the use of ENCPAP. Initial respiratory support with ENCPAP seems to be a safe alternative to routine intubation and mechanical ventilation in premature infants.