Neonatal nasal intermittent positive pressure ventilation efficacy and lung pressure transmission

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..

RAM Cannula versus Short Binasal Prongs for Non-invasive Ventilation in Preterm Infants: An Updated Systematic Review and Meta-analysis

OBJECTIVES

To compare the efficacy and safety of RAM cannula with short binasal prongs (SBPs) as nasal interfaces in preterm infants requiring nasal continuous positive airway pressure (nCPAP) or nasal intermittent positive pressure ventilation (NIPPV).

METHODS

The authors searched electronic databases (Medline, Embase, and Web of Science) and trial registries from inception until March 15, 2024, for randomized controlled trials (RCTs) comparing the RAM cannula with SBP for delivering nCPAP/NIPPV. They performed a random-effects meta-analysis using RevMan 5.4 software. The primary outcome was failure of nCPAP/NIPPV. Secondary outcomes included nasal injury, mechanical ventilation, air leaks, and mortality.

RESULTS

Five RCTs (825 participants) were included. There was no significant difference in nCPAP/NIPPV failure (RR: 1.04; 95% CI: 0.58 to 1.87) or the need for invasive mechanical ventilation (RR: 1.23; 95% CI: 0.75 to 2.01) between the RAM cannula and SBP groups (low to very low certainty). Compared with infants in the SBP group, those in the RAM cannula group had a significantly lower incidence of moderate to severe nasal injury [(5 RCTs, 825 participants; RR: 0.34; 95% CI: 0.18 to 0.66); low certainty] and any nasal injury [(RR: 0.44; 95% CI: 0.26 to 0.76; very low certainty)]. There was no significant difference in the other clinical outcomes.

CONCLUSIONS

In comparison to SBP, the RAM cannula may have little to no effect on nCPAP/NIPPV failure, but the evidence is very uncertain. Low-certainty evidence suggests that the use of RAM cannula possibly results in reduction in moderate to severe nasal trauma in preterm infants receiving nCPAP/NIPPV.

Comparison of two different Nasal Interfaces used in Non-Invasive Respiratory support in terms of Neonate comfort

Background

Non-Invasive Ventilation (NIV) is the first choice approach in neonates with sufficient respiratory effort that require respiratory support. The type of nasal interface used in NIV affects both efficacy and patient comfort. The aim of this study is to investigate the effects of different nasal interfaces used in NIV support on neonatal patient comfort.

Methods

Our study evaluated patients who received NIV support for 24 hours. The patients were randomly divided into two groups according to the type of nasal interface used, which were RAM cannula and short binasal prong (SBP). The patients' demographic and clinical data were noted. Their sleep was monitored for 24 hours with an actigraphy device.

Results

A total of 82 patients were evaluated. The sleep efficiency in the RAM cannula group was significantly higher (respectively, 65.7% [10.22-95.25] vs. 57.81% [2.49-77], p=0.004). Although not statistically significant, the neonates in the RAM cannula group exhibited longer total sleep time (respectively, 10.4 ± 4.28 hours vs. 9.02 ± 3.73 hours, p=0.161). Comparison of heart rates and respiratory rates indicate that the patients in the RAM cannula group were more comfortable.

Conclusions

Our study found that infants who received NIV support through a RAM cannula experienced more efficient sleep. Holistic approaches in neonatal intensive care units are vital for better neurodevelopmental outcomes in newborns. Although non-invasive, the interface used in NIV should also be a part of this holistic approach.

Tidal volume delivery during nasal intermittent positive pressure ventilation: infant cannula vs. nasal continuous positive airway pressure prongs

OBJECTIVE

To measure tidal volume delivery during nasal intermittent positive pressure ventilation with two nasal interfaces: infant cannula and nasal prongs.

STUDY DESIGN

A single-center crossover study of neonates with mild respiratory distress. Fifteen preterm neonates were randomized to initial interface of infant cannula or nasal prongs and monitored on a sequence of pressure settings first on the initial interface, then repeated on the alternate interface. We compared relative tidal volumes between the two interfaces with two-way repeated measures ANOVA during three breath types: synchronized (I), patient effort without ventilator breaths (II), and ventilator breaths without patient effort (III). Clinical trial #NCT04326270.

RESULTS

Type III breaths delivered no significant tidal volume. No significant difference was measured in relative tidal volume delivery between the interfaces when breath types were matched.

CONCLUSIONS

Nasal intermittent positive pressure ventilation delivers neither clinically nor statistically significant tidal volume with either infant cannula or nasal prongs.

Predictors of CPAP failure with RAM cannula interface for primary respiratory support in preterm neonates

Background

RAM cannula is used as interface for delivering nasal continuous positive airway pressure (nCPAP) in many neonatal care units though the bench to bedside evidence for its use in clinical settings in lacking.

Methods

In this prospective cohort study from tertiary care neonatal care unit, the primary objective was to determine the rate of CPAP failure using RAM interface, within 72 h of starting of therapy and secondary objective was to look for the incidence and severity of nasal trauma with the use of RAM interface for CPAP delivery. All inborn preterm neonates between 28 and 32 weeks of gestation and weight more than 1000 g who required non-invasive respiratory support within 6 h of life were included in the study.

Results

The enroled cohort of 250 neonates had mean gestational age of 30.73 ± 1.32 weeks and mean birth weight of 1410 ± 210 g. CPAP failure rate with the use of RAM interface was 31.2% (78/250) in the overall cohort. The failure rate was higher in subgroup of gestation between 28 and 30 week (52.1%) in comparison with the 31-32-week gestation (18.2%; p-value = 0.0001). Nasal trauma was present in 36 (14%) neonates; of whom 33 (91%) had mild and 2 (6%) and 1 (3%) had moderate and severe, respectively. On multivariate analysis, birth weight less than 1250 g, incomplete antenatal steroids, need for PEEP more than 5 cm & FiO2 > 30% at onset of distress and administration of surfactant were found be statistically significantly associated with CPAP failure with RAM interface.

Conclusion

The clinical outcomes with the use of RAM interface for CPAP administration are comparable to those with other interfaces with lesser incidence of nasal injury. The results of this study warrant future randomized trials to compare different CPAP interfaces for clinical outcomes and nasal injuries from the developing countries.

Respiratory management of established severe bronchopulmonary dysplasia

Respiratory management of infants with established severe BPD is difficult and there is little evidence upon which to base decisions. Nonetheless, the physiology of severe BPD is well described with a predominantly obstructive pattern. This pulmonary dysfunction results in prolonged exhalatory time constants and thus ventilator management must be focused on maintaining adequate oxygenation and ventilation through achieving full exhalation. This approach is often difficult to maintain in acute care settings and a culture of chronic care focused on slow change and steady progress is imperative. Once respiratory stability is achieved, the focus should shift to growth and development and avoidance of care practices and medications that impair neurodevelopment.

State of the art on neonatal noninvasive respiratory support: How physiological and technological principles explain the clinical outcomes

Noninvasive respiratory support has gained significant popularity in neonatal units because of its potential to reduce lung injury associated with invasive mechanical ventilation. To minimize lung injury, clinicians aim to apply for noninvasive respiratory support as early as possible. However, the physiological background and the technology behind such support modes are not always clear, and many open questions remain regarding the indications of use and clinical outcomes. This narrative review discusses the currently available evidence for various noninvasive respiratory support modes applied in Neonatal Medicine in terms of physiological effects and indications. Reviewed modes include nasal continuous positive airway pressure, nasal high-flow therapy, noninvasive high-frequency oscillatory ventilation, nasal intermittent positive pressure ventilation (NIPPV), synchronized NIPPV and noninvasive neurally adjusted ventilatory assist. To enhance clinicians' awareness of each support mode's strengths and limitations, we summarize technical features related to the functioning mechanisms of devices and the physical properties of the interfaces commonly used for providing noninvasive respiratory support to neonates. We finally address areas of current controversy and suggest possible areas of research for implementing noninvasive respiratory support in neonatal intensive care units.

Ultrasonographic assessment of diaphragmatic function in preterm infants on non-invasive neurally adjusted ventilatory assist (NIV-NAVA) compared to nasal intermittent positive-pressure ventilation (NIPPV): a prospective observational study

NIV-NAVA mode for respiratory support in preterm infants is not well-studied. This study aimed to describe the diaphragmatic function, diaphragmatic excursion (DE), and thickness fraction (DTF), in preterm infants < 30 weeks' gestation supported by NIV-NAVA compared to NIPPV using bedside ultrasonography. In this consecutive prospective study, DE, diaphragmatic thickness at end of expiration (DT_exp), end of inspiration (DT_ins), and DTF were assessed using bedside ultrasound. Lung aeration evaluation using lung ultrasound score (LUS) was performed for the two groups. Diaphragmatic measurements and LUS were compared for the 2 groups (NIV-NAVA group versus NIPPV group). Statistical analyses were conducted using the SPSS software version 22. Out of 70 infants evaluated, 40 were enrolled. Twenty infants were on NIV-NAVA and 20 infants on NIPPV with a mean [SD] study age of 25.7 [0.9] weeks and 25.1 [1.4] weeks respectively (p = 0.15). Baseline characteristics and respiratory parameters at the time of the scan showed no significant difference between groups. DE was significantly higher in NIV-NAVA with a mean SD of 4.7 (1.5) mm versus 3.5 (0.9) mm in NIPPV, p = 0.007. Additionally, the mean (SD) of DTF for the NIV-NAVA group was 81.6 (30) % vs 78.2 (27) % for the NIPPV group [p = 0.71]. Both groups showed relatively high LUS but no significant difference between groups [12.8 (2.6) vs 12.6 (2.6), p = 0.8].  Conclusion: Preterm infants managed with NIV-NAVA showed significantly higher DE compared to those managed on NIPPV. This study raises the hypothesis that NIV-NAVA could potentially improve diaphragmatic function due to its synchronization with patients' own breathing. Longitudinal studies to assess diaphragmatic function over time are needed.  Trial registry: Clinicaltrials.gov (NCT05079412). Date of registration September 30, 2021. What is Known: • NIV-NAVA utilizes diaphragmatic electrical activity to provide synchronized breathing support. • Evidence for the effect of NIV-NAVA on diaphragmatic thickness fraction (DTF) and excursion (DE) is limited. What is New: • Ultrasonographic assessment of diaphragmatic function (DTF and DE) is feasible. • In preterm infants, DE was significantly higher in infants supported with NIV-NAVA compared to those supported with NIPPV.

RAM cannula versus short binasal prongs for nasal continuous positive airway pressure delivery in preterm infants: a randomized, noninferiority trial from low-middle-income country

To determine if RAM cannula is non-inferior to short binasal prongs (SBP) in providing nasal continuous positive airway pressure (CPAP) in preterm infants with respiratory distress syndrome (RDS). In this randomized, open-label, noninferiority trial from a low-middle-income country, we enrolled 254 preterm infants (28-34 weeks gestational age) with RDS who needed CPAP as primary respiratory support. The eligible infants were randomized to either RAM cannula or SBP interface groups. The primary outcome was CPAP failure (defined as the need for intubation or non-invasive positive pressure ventilation) within 72 h of randomization. The noninferiority margin was defined as a 10% or less absolute difference in CPAP failure rates. The secondary outcomes included nasal trauma and adverse events. We analyzed by per-protocol (primary) and intention to treat. CPAP failure has been seen in 25 infants (19.7%) in the RAM cannula group versus 22 (17.3%) in the SBP group (RD -2.36%; 95% CI -11.9 to 7.2 [beyond inferiority margin]; p = 0.6). Moderate and severe nasal trauma was less in RAM cannula (2.4 vs. 8.7%; RR 0.27; 95% CI 0.08-0.95; p 0.028). Duration of CPAP was also significantly shorter in the RAM cannula group (MD -12.4 h; 95% CI -20.34 to -4.46, p 0.017). There were no differences in other adverse events.

CONCLUSIONS

RAM cannula was not non-inferior to SBP in providing CPAP to preterm infants with respiratory distress syndrome.

TRIAL REGISTRATION

Registered at Clinical Trial Registry of India (CTRI/2020/03/024097).

WHAT IS KNOWN

• RAM cannula is used for providing supplemental oxygen therapy. There is conflicting evidence on its efficacy in delivering CPAP support in preterm infants.

WHAT IS NEW

• RAM cannula was not non-inferior to SBP in providing CPAP to preterm infants with respiratory distress syndrome. • RAM cannula causes less nasal trauma than short binasal prongs.

AK, Razak A, Trevisanuto D. Nasal Cannula with Long and Narrow Tubing for Non-Invasive Respiratory Support in Preterm Neonates: A Systematic Review and Meta-Analysis

Background: Cannulas with long and narrow tubing (CLNT) are increasingly being used as an interface for noninvasive respiratory support (NRS) in preterm neonates; however, their efficacy compared to commonly used nasal interfaces such as short binasal prongs (SBP) and nasal masks (NM) has not been widely studied. Material and Methods: Medline, Embase, CENTRAL, Health Technology Assessment Database, and Web of Science were searched for randomized clinical trials (RCTs) and observational studies investigating the efficacy of CLNT compared to SBP or NM in preterm neonates requiring NRS for primary respiratory and post-extubation support. A random-effects meta-analysis was used for data synthesis. Results: Three RCTs and three observational studies were included. Clinical benefit or harm could not be ruled out for the outcome of need for invasive mechanical ventilation (IMV) for CLNT versus SBP or NM [relative risk (RR) 1.37, 95% confidence interval (CI) 0.61–3.04, certainty of evidence (CoE) low]. The results were also inconclusive for the outcome of treatment failure [RR 1.20, 95% CI 0.48–3.01, CoE very low]. Oropharyngeal pressure transmission was possibly lower with CLNT compared to other interfaces [MD −1.84 cm H20, 95% CI −3.12 to −0.56, CoE very low]. Clinical benefit or harm could not be excluded with CLNT compared to SBP or NM for the outcomes of duration of IMV, nasal trauma, receipt of surfactant, air leak, and NRS duration. Conclusion: Very low to low CoE and statistically nonsignificant results for the clinical outcomes precluded us from making any reasonable conclusions; however, the use of CLNT as an NRS interface, compared to SBP or NM, possibly transmits lower oropharyngeal pressures. We suggest adequately powered multicentric RCTs to evaluate the efficacy of CLNT when compared to other interfaces.

Nasal Continuous Positive Airway Pressure vs. Nasal Intermittent Positive Pressure Ventilation as Initial Treatment After Birth in Extremely Preterm Infants

Objective

Non-invasive respiratory support strategies are known to reduce the complications of invasive mechanical ventilation in preterm infants. Nasal continuous positive airway pressure (NCPAP) and nasal intermittent positive pressure ventilation (NIPPV) are commonly used ones. The recent meta-analyses indicated that early NIPPV did appear to be superior to NCPAP for decreasing respiratory failure and the need for intubation among preterm infants with respiratory distress syndrome (RDS). The aim of the study was to compare the short-term outcomes of extremely preterm infants who received NCPAP or NIPPV as an initial treatment of RDS.

Methods

This retrospective study included infants born before 29 weeks' gestation between 1 January 2018 and 31 December 2021 who received non-invasive respiratory support with NCPAP or NIPPV. For every infant included in the cohort, only the first episode of NCPAP or NIPPV as initial treatment was evaluated. The primary outcome was the need for intubation within 72 h, and the secondary outcomes were the need for intubation within 7 days, administration of surfactant, prematurity-related morbidities, mortality, and death or bronchopulmonary dysplasia (BPD).

Results

During the study period, there were 116 inborn admissions of preterm infants born <29 weeks' gestation and 60 of them met the inclusion criteria. Of these, 31 (52%) infants received NCPAP while 29 (48%) infants received NIPPV at the first hours after birth. There were no differences in the baseline demographics between the groups (p > 0.05). Blood gas parameters (pH, pCO2, HCO3, and lactate) at admission were not different. The need for intubation within 72 h as the primary outcome was similar between NCPAP and NIPPV groups (35.5 vs. 34.5%, p = 0.935). The rates of surfactant requirement, need for intubation within 7 days, prematurity-related morbidities, mortality, and death/BPD were similar among the groups (p > 0.05).

Conclusion

Nasal intermittent positive pressure ventilation is non-inferior to NCPAP as an initial treatment in extremely preterm infants with RDS. Although the rate of intubation in the first week, mortality, and BPD did not differ between groups, additional studies are needed and the synchronization of NIPPV should be evaluated.

Novel Ventilation Strategies to Reduce Adverse Pulmonary Outcomes

Extremely preterm infants who must suddenly support their own gas exchange with lungs that are incompletely developed and lacking adequate amount of surfactant and antioxidant defenses are susceptible to lung injury. The decades-long quest to prevent bronchopulmonary dysplasia has had limited success, in part because of increasing survival of more immature infants. The process must begin in the delivery room with gentle assistance in establishing and maintaining adequate lung aeration, followed by noninvasive support and less invasive surfactant administration. Various modalities of invasive and noninvasive support have been used with varying degree of effect and are reviewed in this article.

Patient-Ventilator Synchrony in Extremely Premature Neonates during Non-Invasive Neurally Adjusted Ventilatory Assist or Synchronized Intermittent Positive Airway Pressure: A Randomized Crossover Pilot Trial

INTRODUCTION

Synchronization of non-invasive ventilation is challenging in extremely premature infants. We compared patient-ventilator synchrony between non-invasive neurally adjusted ventilatory assist (NIV-NAVA) using transdiaphragmatic (Edi) catheter and synchronized intermittent positive airway pressure (SiPAP) using an abdominal trigger.

METHODS

This study was a monocentric, randomized, crossover trial in premature infants born before 28 weeks of gestation, aged 3 days or more, and below 32 weeks postmenstrual age. NIV-NAVA and SiPAP were applied in a random order for 2 h with analysis of data from the second hour. The primary outcome was the asynchrony index.

RESULTS

Fourteen patients were included (median [IQR] gestational age at birth 25.6 (25.3-26.4) weeks, median [IQR] birth weight 755 [680-824] g, median [IQR] postnatal age 26.5 [19.8-33.8] days). The median (IQR) asynchrony index was significantly lower in NIV-NAVA versus SiPAP (49.9% [44.1-52.6] vs. 85.8% [74.2-90.9], p < 0.001). Ineffective efforts and auto-triggering were significantly less frequent in NIV-NAVA versus SiPAP (3.0% vs. 32.0% p < 0.001 and 10.0% vs. 26.6%, p = 0.004, respectively). Double triggering was significantly less frequent in SiPAP versus NIV-NAVA (0.0% vs. 9.0%, p < 0.001). No significant difference was observed for premature cycling and late cycling. Peak Edi and swing Edi were significantly lower in NIV-NAVA as compared to SiPAP (7.7 [6.1-9.9] vs. 11.0 [6.7-14.5] μV, p = 0.006; 5.4 [4.2-7.6] vs. 7.6 [4.3-10.8] μV, p = 0.007, respectively). No significant difference was observed between NIV-NAVA and SiPAP for heart rate, respiratory rate, COMFORTneo scores, apnoea, desaturations, or bradycardias.

DISCUSSION/CONCLUSION

NIV-NAVA markedly improves patient-ventilator synchrony as compared to SiPAP in extremely premature infants.

RAM cannula with Cannulaide versus Hudson prongs for delivery of nasal continuous positive airway pressure in preterm infants: an RCT

Nasal continuous positive airway pressure (nCPAP) is the standard non-invasive respiratory support for newborns with respiratory distress. Nasal injury is a common problem with the interfaces used. To compare the incidence and severity of nasal injury in neonates with respiratory distress and supported on nCPAP with Hudson prong or RAM cannula with Cannulaide, a semipermeable membrane. This is an open-label, parallel-arm, gestational age-stratified, bi-centric, randomized control trial including neonates between 28 and 34 weeks gestational age and birth weight > 1000 g needing nCPAP. The size of the interface was chosen as per the manufacturer’s recommendation. Of the 229 neonates enrolled, 112 were randomized to RAM cannula with Cannulaide and 117 to Hudson prong. The baseline characteristics were similar. Any nasal injury at CPAP removal was significantly lower in the RAM cannula with Cannulaide group [6 (5.4%) vs. 31 (26.4%); risk ratio—0.77 (95% CI 0.69–0.87); p = 0.0001]. The incidence of moderate to severe nasal injury, need for mechanical ventilation within 72 h of age, duration of oxygen, and requirement of nCPAP for > 3 days were similar. For preterm infants on nCPAP, RAM cannula with Cannulaide, compared to Hudson prongs, decreases nasal injury without increasing the need for mechanical ventilation.

Trail registration: CTRI/2019/03/018333, http://www.ctri.nic.in.

Nasal High-Frequency Ventilation

Noninvasive high-frequency oscillatory (NHFOV) and percussive (NHFPV) ventilation represent 2 nonconventional techniques that may be useful in selected neonatal patients. We offer here a comprehensive review of physiology, mechanics, and biology for both techniques. As NHFOV is the technique with the wider experience, we also provided a meta-analysis of available clinical trials, suggested ventilatory parameters boundaries, and proposed a physiology-based clinical protocol to use NHFOV.

Use of the RAM Cannula with Early Bubble Continuous Positive Airway Pressure Requires Higher Pressures: Clinical and In vitro Evaluations

OBJECTIVE

Early bubble continuous positive airway pressure (bCPAP) in the delivery room (DR) reduces early intubation, mechanical ventilation, and bronchopulmonary dysplasia. The RAM cannula, adopted for ease of patient care, is a high resistance nasal interface that, when used with bCPAP, only transmits a portion of set pressures and attenuates the bubble effects. This study aimed to review early bCPAP pressures and bCPAP failure with the RAM cannula interface over a 6-year period.

STUDY DESIGN

Retrospective, single-center study of infants delivered <1,250 g from 2013 to 2018 (n = 735) begun on bCPAP in the DR with the RAM cannula. In vitro testing of bCPAP pressure transmission was also performed for multiple nasal interfaces and nasal occlusion percentages.

RESULTS

The percentage of infants intubated in the DR decreased over time (59 to 42%), while the average bCPAP pressure increased from 5.3 to 6.8 cmH₂O. A total of 355 infants (48%) were admitted to the neonatal intensive care unit (NICU) from the DR on BCPAP. The failure rate for bCPAP in NICU within 72 hours decreased from 45 to 24% as the maximum CPAP increased from 5.8 to 7.6 cmH₂O. Pneumothorax rates did not change. CPAP pressure transmission decreased with all sizes of the RAM cannula.

CONCLUSION

When utilizing the RAM cannula for bCPAP, higher CPAP levels were associated with decreases in DR intubations and CPAP failure within the first 72 hours. If clinicians choose to use the RAM cannula for bCPAP, they will need higher set pressures to achieve lung inflation and the beneficial oscillatory effect will be diminished.

KEY POINTS

· The transmission of the pressure oscillations from bubble CPAP is diminished with the RAM cannula.. · Increasing set CPAP pressures was associated with a decreased delivery room intubation rate and a decreased CPAP failure rate within 72 hours.. · Clinicians using the RAM cannula for bCPAP will need to increase pressures to obtain adequate lung inflation or change to a nasal interface designed for bCPAP..

Role of ventilator and nasal interface in pressure transmission during neonatal intermittent positive pressure ventilation: A bench study

We aimed at evaluating pressure transmission and stability during non-synchronized neonatal nasal intermittent positive pressure ventilation (NIPPV) delivered using five mechanical ventilators and three nasal interfaces. An artificial nose-throat model was connected to a mechanical analog of the infant respiratory system and a breath generator. Ventilation was administrated via a nasal mask (NM), short bi-nasal prongs (SBN), or RAM® cannula. We applied positive end-expiratory pressures (PEEP) of 5 and 10 cmH₂ O, inspiratory pressures (PIP) of 15 and 30 cmH₂ O, inspiratory times of 0.23, 0.42, and 0.57 s. Measurements were performed with leaks of 0, 1.5, and 4 L/min. The pressure was measured at the airways opening (P_AW ) and the glottis (P_GL ). The difference between set and delivered pressures (P_AW ) was less than ±1 cmH₂ O for all ventilators. We documented a significant difference between P_AW and P_GL in the presence of leaks. With 4 L/min leaks, PEEP dropped by 43%, 49%, and 63% with NM, SBP, and RAM® cannula, respectively; PIP dropped by 58%, 64%, and 74%. On average, the SD of PEEP fluctuations was ±0.60 and ±2.50 cmH₂ O for P_AW and P_GL ; the breath-by-breath SD of PIP was ±0.77 and ±2.06 cmH₂ O. During NIPPV, the PIP and PEEP transmission to the glottis is markedly lower than the set values and highly variable. The impact of leaks and nasal interface is much more significant than the differences in ventilators' performance on the efficacy of pressure transmission and stability of non-synchronized ventilator-generated NIPPV.

Non-Invasive Ventilatory Strategies to Decrease Bronchopulmonary Dysplasia-Where Are We in 2021?

Recent advances in neonatology have led to the increased survival of extremely low-birth weight infants. However, the incidence of bronchopulmonary dysplasia (BPD) has not improved proportionally, partly due to increased survival of extremely premature infants born at the late-canalicular stage of lung development. Due to minimal surfactant production at this stage, these infants are at risk for severe respiratory distress syndrome, needing prolonged ventilation. While the etiology of BPD is multifactorial with antenatal, postnatal, and genetic factors playing a role, ventilator-induced lung injury is a major, potentially modifiable, risk factor implicated in its causation. Infants with BPD are at a higher risk of developing complications including sepsis, pulmonary arterial hypertension, respiratory failure, and death. Long-term problems include increased risk of hospital readmissions, respiratory infections, and asthma-like symptoms during infancy and childhood. Survivors who have BPD are also at increased risk of poor neurodevelopmental outcomes. While the ultimate solution for avoiding BPD lies in the prevention of preterm births, strategies to decrease its incidence are the need of the hour. It is time to focus on gentler modes of ventilation and the use of less invasive surfactant administration techniques to mitigate lung injury, thereby potentially decreasing the burden of BPD. In this article, we discuss the use of non-invasive ventilation in premature infants, with an emphasis on studies showing an effect on BPD with different modes of non-invasive ventilation. Practical considerations in the use of nasal intermittent positive pressure ventilation are also discussed, considering the significant heterogeneity in clinical practices and management strategies in its use.

Flow-synchronized NIPPV with double-inspiratory loop cannula: An in vitro study

BACKGROUND

Although short binasal prongs (SBP) are the most common interface for noninvasive ventilation, the "double-inspiratory loop cannulas" (DILC) have recently been introduced into many neonatal intensive care units. DILC show advantages over SBP, including reduced nasal trauma and increased comfort. However, their higher intrinsic resistance may compromise ventilation. Our aim was to test a new, low resistance DILC interface.

METHODS

A test lung was programmed to simulate preterm neonates (500-2000 g BW) with moderate-to-severe respiratory distress syndrome. The artificial nose was designed to keep prongs-to-nares leaks to around 30%. Giulia® ventilator (GINEVRI srl) was used to provide nasal continuous positive airway pressure (NCPAP) and flow synchronized nasal intermittent positive pressure ventilation (NIPPV). NCPAP was set at 4-10 cmH₂ O and synchronized-NIPPV (SNIPPV) at peak inspiratory pressure, 15-20-25 cmH₂ O; inspiratory time, 0.3-0.5 s; and positive end-expiratory pressure, 5-8 cmH₂ O. Four sizes of Sync-flow Cannula® (GINEVRI srl) were tested. The Sync-flow Cannula® was compared with Neotech RAM® cannula and Ginevri SBP®. The outcome measures were the flow/pressure relationship through the four Sync-flow Cannula® sizes, the difference in resistance, the drop in ventilator-alveoli pressure measured by the test lung and the system response time during flow-SNIPPV.

RESULTS

The smaller DILC sizes had the lowest flow-pressure ratio. The resistance of the RAM® cannula was significantly higher compared to the other interfaces (p < .001). With 30% leaks, there was a 4-38% ventilator-alveoli drop in pressure, depending on interface size. The system response time was excellent (~65-70 ms).

CONCLUSIONS

With about 30% leaks, the Sync-flow Cannula® interfaces result in good pressure transmission and give optimal performance for flow-SNIPPV. Clinical studies are needed to confirm the clinical relevance of these data.

Ventilation Strategies in Severe Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is an acquired, developmental chronic lung disease that is a consequence of premature birth. In the most severe form of the disease, infants may require prolonged periods of positive pressure ventilation. BPD is a heterogeneous disease with lung mechanics that differ from those in respiratory distress syndrome; strategies to manage the respiratory support in infants with severe BPD should take this into consideration. When caring for these infants, practitioners need to shift from the acute care ventilation strategies that use frequent blood gases and support adjustments designed to minimize exposure to positive pressure. Infants with severe BPD benefit from a chronic care model that uses less frequent ventilator adjustments and provides the level of positive support that will achieve the longer-term goal of ongoing lung growth and repair.

Predicting Failure of Non-Invasive Ventilation With RAM Cannula in Bronchiolitis

INTRODUCTION

In infants hospitalized for bronchiolitis on non-invasive ventilation (NIV) via the RAM cannula nasal interface, variables predicting subsequent intubation, or NIV non-response, are understudied. We sought to identify predictors of NIV non-response.

METHODS

We performed a retrospective cohort study in infants admitted for respiratory failure from bronchiolitis placed on NIV in a quaternary children's hospital. We excluded children with concurrent sepsis, critical congenital heart disease, or with preexisting tracheostomy. The primary outcome was NIV non-response defined as intubation after a trial of NIV. Secondary outcomes were vital sign values before and after NIV initiation, duration of NIV and intubation, and mortality. Primary analyses included Chi-square, Wilcoxon rank-sum, student's t test, paired analyses, and adjusted and unadjusted logistic regression assessing heart rate (HR) and respiratory rate (RR) before and after NIV initiation.

RESULTS

Of 138 infants studied, 34% were non-responders. There were no differences in baseline characteristics of responders and non-responders. HR decreased after NIV initiation in responders (156 [143-156] to149 [141-158], p < 0.01) compared to non-responders (158 [149-166] to 158 [145-171], p = 0.73). RR decreased in responders (50 [43-58] vs 47 [41-54]) and non-responders (52 [48-58] vs 51 [40-55], both p < 0.01). Concurrent bacterial pneumonia (OR 6.06, 95% CI: 2.54-14.51) and persistently elevated HR (OR: 1.04, 95% CI: 1.01-1.07) were associated with NIV non-response.

CONCLUSION

In children with acute bronchiolitis who fail to respond to NIV and require subsequent intubation, we noted associations with persistently elevated HR after NIV initiation and concurrent bacterial pneumonia.

Bi-Level Noninvasive Ventilation in Neonatal Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis

BACKGROUND

Bi-level noninvasive ventilation (NIV) has been used in respiratory distress syndrome (RDS) as primary treatment, post-extubation, and to treat apnea. This review summarizes studies on bi-level NIV in premature infants with RDS. Nonsynchronized nasal intermittent positive pressure ventilation (nsNIPPV) and synchronized NIPPV (SNIPPV) use pressure settings ≥ those used during mechanical ventilation (MV), and biphasic continuous positive airway pressure (BiPAP) use two nasal continuous positive airway pressure (NCPAP) levels ≤4 cm H2O apart.

METHODS

A systematic review (Medline OVID and Pubmed) and meta-analysis of randomized controlled trials. Primary outcomes were bronchopulmonary dysplasia (BPD) and mortality. Secondary outcomes included NIV failure (intubation) and extubation failure (re-intubation). Data were pooled using a fixed-effects model to calculate the relative risk (RR) with 95% confidence interval (CI) between NIV modes (RevMan v 5.3, Copenhagen, Denmark).

RESULTS

Twenty-four randomized controlled trials that largely did not correct for mean airway pressure (MAP) and used outdated ventilators were included. Compared with NCPAP, both nsNIPPV and SNIPPV resulted in less re-intubation (RR 0.88 with 95% CI (0.80, 0.97) and RR 0.20 (0.10, 0.38), respectively) and BPD (RR 0.69 (0.49, 0.97) and RR 0.51 (0.29, 0.88), respectively). nsNIPPV also resulted in less intubation (RR 0.57 (0.45, 0.73) versus NCPAP, with no difference in mortality. One study showed less intubation in BiPAP versus NCPAP.

CONCLUSIONS

Bi-level NIV versus NCPAP may reduce MV and BPD in premature infants with RDS. Studies comparing equivalent MAP utilizing currently available machines are needed.

Cannula With Long and Narrow Tubing vs Short Binasal Prongs for Noninvasive Ventilation in Preterm Infants: Noninferiority Randomized Clinical Trial

IMPORTANCE

Use of cannulas with long and narrow tubing (CLNT) has gained increasing popularity for applying noninvasive respiratory support for newborn infants thanks to ease of use, perceived patient comfort, and reduced nasal trauma. However, there is concern that this interface delivers reduced and suboptimal support.

OBJECTIVE

To determine whether CLNT is noninferior to short binasal prongs and masks (SPM) when providing nasal intermittent positive pressure ventilation (NIPPV) in preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

This randomized controlled, unblinded, prospective noninferiority trial was conducted between December 2017 and December 2019 at 2 tertiary neonatal intensive care units. Preterm infants born between 24 weeks' and 33 weeks and 6 days' gestation were eligible if presented with respiratory distress syndrome with the need for noninvasive ventilatory support either as initial treatment after birth or after first extubation. Analysis was performed by intention to treat.

INTERVENTIONS

Randomization to NIPPV with either CLNT or SPM interface.

MAIN OUTCOMES AND MEASURES

The primary outcome was the need for intubation within 72 hours after NIPPV treatment began. Noninferiority margin was defined as 15% or less absolute difference.

RESULTS

Overall, 166 infants were included in this analysis, and infant characteristics and clinical condition (including fraction of inspired oxygen, Pco2, and pH level) were comparable at recruitment in the CLNT group (n = 83) and SPM group (n = 83). The mean (SD) gestational age was 29.3 (2.2) weeks vs 29.2 (2.5) weeks, and the mean (SD) birth weight was 1237 (414) g vs 1254 (448) g in the CLNT and SPM groups, respectively. Intubation within 72 hours occurred in 12 of 83 infants (14%) in the CLNT group and in 15 of 83 infants (18%) in the SPM group (risk difference, -3.6%; 95% CI, -14.8 to 7.6 [within the noninferiority margin], χ2 P = .53). Moderate to severe nasal trauma was significantly less common in the CLNT group compared with the SPM group (4 [5%] vs 14 [17%]; P = .01). There were no differences in other adverse events or in the course during hospitalization.

CONCLUSIONS AND RELEVANCE

In this study, CLNT was noninferior to SPM in providing NIPPV for preterm infants, while causing significantly less nasal trauma.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03081611.

Non-invasive Respiratory Support of the Premature Neonate: From Physics to Bench to Practice

Premature births continue to rise globally with a corresponding increase in various morbidities among this population. Rates of respiratory distress syndrome and the consequent development of Bronchopulmonary Dysplasia (BPD) are highest among the extremely preterm infants. The majority of extremely low birth weight premature neonates need some form of respiratory support during their early days of life. Invasive modes of respiratory assistance have been popular amongst care providers for many years. However, the practice of prolonged invasive mechanical ventilation is associated with an increased likelihood of developing BPD along with other comorbidities. Due to the improved understanding of the pathophysiology of BPD, and technological advances, non-invasive respiratory support is gaining popularity; whether as an initial mode of support, or for post-extubation of extremely preterm infants with respiratory insufficiency. Due to availability of a wide range of modalities, wide variations in practice exist among care providers. This review article aims to address the physical and biological basis for providing non-invasive respiratory support, the current clinical evidence, and the most recent developments in this field of Neonatology.

Nasal continuous positive airway pressure (NCPAP) or noninvasive neurally adjusted ventilatory assist (NIV-NAVA) for preterm infants with respiratory distress after birth: A randomized controlled trial

OBJECTIVES

To compare rates of treatment failure between the use of nasal continuous positive airway pressure (NCPAP) and noninvasive neurally adjusted ventilatory assist (NIV-NAVA) in infants with respiratory distress after birth.

METHODS

A randomized, unblinded, double-center trial was conducted in infants with birth weights (BWs) less than or equal to 1500 g and respiratory distress receiving noninvasive respiratory support for less than or equal to 48 hours of life; some infants were initially treated with minimally invasive surfactant therapy as the standard of care.

PRIMARY OUTCOME

need for endotracheal intubation with use of mechanical ventilation (MV) at less than or equal to 72 hours of life using prespecified failure criteria.

SECONDARY OUTCOMES

use of surfactant, duration of noninvasive support, duration of MV, bronchopulmonary dysplasia (BPD) and death.

RESULTS

A total of 123 infants were included (NCPAP group = 64 and NIV-NAVA group = 59). Population characteristics were similar between groups. No difference in the primary outcome was observed: NCPAP = 10 (15.6%) and NIV-NAVA = 12 (20.3%), P = .65. Groups were also similar in the use of surfactant (19 vs 17), duration of noninvasive support (147 ± 181 hours vs 127 ± 137 hours), BPD incidence and death. However, duration of MV was significantly longer in NCPAP group (95.6 ± 45.8 hours vs 28.25 ± 34.1 hour), P = .01.

CONCLUSION

In infants with respiratory distress after birth, no differences in treatment failures were observed between NIV-NAVA and NCPAP. These results require further evaluation in a larger study.

A randomized trial comparing the short binasal prong to the RAM cannula for noninvasive ventilation support of preterm infants with respiratory distress syndrome

PURPOSE

In this study, we compared the efficacy of the RAM cannula and the short binasal prong (SBP) as noninvasive ventilation (NIV) interfaces in preterm infants with respiratory distress syndrome (RDS).

MATERIALS AND METHODS

Premature infants with RDS who required NIV were randomized in the RAM cannula and SBP groups within the first half hour. The groups were compared in terms of their need for invasive ventilation, their surfactant use, and their morbidities.

RESULTS

We assessed 126 patients (62 SBPs and 64 RAM cannulas). Clinical and demographic features of the groups were similar. Within the first 72 hours, the RAM cannula group showed a higher need for invasive ventilation (32.8 and 9.6%, p = .002, respectively), surfactant (42.1 and 19.3%, p = .007, respectively), and rate of pulmonary hemorrhage was also higher. There were no differences between the groups in terms of other morbidities.

CONCLUSIONS

In preterm infants with RDS, RAM cannula use as an interface for NIV results in increased invasive ventilation and surfactant use.

Continuous positive airway pressure (CPAP) vs noninvasive positive pressure ventilation (NIPPV) vs noninvasive high frequency oscillation ventilation (NHFOV) as post-extubation support in preterm neonates: protocol for an assessor-blinded, multicenter, randomized controlled trial

BACKGROUND

Various noninvasive respiratory support modalities are available in neonatal critical care in order to minimize invasive ventilation. Continuous positive airway pressure (CPAP) is the more commonly used but noninvasive positive pressure ventilation (NIPPV) seems more efficacious in the early post-extubation phase, although it is not clear if NIPPV may influence longterm outcomes. A recently introduced alternative is noninvasive high frequency oscillatory ventilation (NHFOV) which might be especially useful in babies needing high constant distending pressure. Preterm neonates may receive these respiratory supports for several weeks. Nonetheless, no data are available for the longterm use of NIPPV and NHFOV; few data exist on NHFOV and clinical outcomes, although its safety and suitability are reported in a number of preliminary short-term studies.

METHODS

We designed an assessor-blinded, multicenter, three-arms, parallel, pragmatic, randomized, controlled trial with a superiority design, investigating the use of CPAP vs NIPPV vs NHFOV during the whole stay in neonatal intensive care units in China. Since safety data will also be analyzed it may be considered a phase II/III trial. Moreover, subgroup analyses will be performed on patients according to prespecified criteria based on physiopathology traits: these subgroup analyses should be considered preliminary. At least 1440 neonates are supposed to be enrolled. The trial has been designed with the collaboration of international colleagues expert in NHFOV, who will also perform an interim analysis at the about 50% of the enrolment.

DISCUSSION

The study is applying the best trial methodology to neonatal ventilation, a field where it is often difficult to do so for practical reasons. Nonetheless, ours is also a physiology-driven trial, since interventions are applied based on physiological perspective, in order to use ventilatory techniques at their best. The pragmatic design will increase generalizability of our results but subgroup analyses according to predefined physiopathological criteria are also previewed trying to have some advantages of an explanatory design. Since not all clinicians are well versed in all respiratory techniques, the training is pivotal. We intend to apply particular care to train the participating units: a specific 3-month period and several means have been dedicated to this end.

TRIAL REGISTRATION

NCT03181958 (registered on June 9, 2017).

Tidal volume transmission during non-synchronized nasal intermittent positive pressure ventilation via RAM® cannula

BACKGROUND

Nasal intermittent positive pressure ventilation (NIPPV) is a widely used mode of support in neonates, during which ventilator inflations may or may not coincide with spontaneous breathing.

OBJECTIVE

We tested the hypothesis that inflations delivered with NIPPV via RAM^® cannula and not accompanied by patient effort produce minimal tidal volume as measured by respiratory inductance plethysmography.

DESIGN/METHODS

Fourteen subjects were monitored while receiving NIPPV. We compared tidal volumes during ventilator-supported breaths, unsupported breaths, and ventilator inflations not accompanied by patient effort (defined using electrical activity of the diaphragm).

RESULTS

Mean tidal volumes in arbitrary units were 0.30 ± 0.22 in NIPPV inflations associated with patient effort and 0.27 ± 0.15 in spontaneous breaths without ventilator assistance (p = 0.82). Tidal volumes during ventilator-only inflations were 0.06 ± 0.04 (p < 0.005 vs. both ventilator-assisted and unassisted efforts).

CONCLUSIONS

NIPPV via RAM cannula produces minimal, clinically insignificant tidal volumes during non-spontaneous inflations.

Preventing Continuous Positive Airway Pressure Failure: Evidence-Based and Physiologically Sound Practices from Delivery Room to the Neonatal Intensive Care Unit

Routine use of continuous positive airway pressure (CPAP) to support preterm infants with respiratory distress is an evidenced-based strategy to decrease incidence of bronchopulmonary dysplasia. However, rates of CPAP failure remain unacceptably high in very premature neonates, who are at high risk for developing bronchopulmonary dysplasia. Using the GRADE framework to assess the quality of available evidence, this article reviews strategies aimed at decreasing CPAP failure, starting with delivery room interventions and followed through to system-based efforts in the neonatal intensive care unit. Despite best efforts, some very premature neonates fail CPAP. Also reviewed are predictors of CPAP failure in this vulnerable population.

Continuous positive airway pressure delivery during less invasive surfactant administration: a physiologic study

OBJECTIVE

We sought to investigate the pressure delivery during less invasive surfactant administration, as we hypothesize that it might be reduced.

STUDY DESIGN

Physiologic in vitro study in a ventilation lab, using different pressure generators, levels, and leaks in a model of neonatal airways/lung mimicking mechanical characteristics of respiratory distress syndrome. Pressure was measured at the lung and verified in vivo measuring pharyngeal pressure in 19 neonates under same conditions. Data were analyzed using repeated measures-analysis of variance.

RESULTS

Pressure delivery in vitro is significantly and variably reduced during minimally invasive surfactant administration: pressure loss is ≈99% and ≈10-97%, during mouth opening and closure, respectively. Pressure loss seems independent from the type of CPAP and interface. In vivo measurements showed similar pressure drops.

CONCLUSIONS

Pressure transmission during minimally invasive surfactant administration is significantly reduced or totally absent. Pressure drop occurs despite the increased airway resistances and the airflow limitation due to the tracheal catheterization, but is independent from the type of pressure generator and interface.

[Research advances in neonatal nasal intermittent positive pressure ventilation]

Nasal intermittent positive pressure ventilation (NIPPV) can augment nasal continuous positive airway pressure (nCPAP) by delivering intermittent positive pressure ventilation in a noninvasive way and can provide a new option for neonatal noninvasive respiratory support. NIPPV has an advantage over nCPAP in primary and post-extubation respiratory support. Moreover, it can reduce severe apnea of prematurity. Synchronized NIPPV has promising application prospects. This review article summarizes the advances in the application of NIPPV in neonatal respiratory support to promote the understanding and standardization of this technique.

[Research advances in noninvasive high-frequency oscillatory ventilation in neonates]

Noninvasive ventilation is an important respiratory management technique for the treatment of mild or moderate respiratory failure in the neonatal intensive care unit. Its reasonable application can effectively avoid the use of invasive ventilation and related complications. Recent studies have found that noninvasive high-frequency oscillatory ventilation has the advantages of both nasal continuous positive airway pressure and high-frequency ventilation and can rapidly improve oxygenation, effectively remove carbon dioxide, and improve respiratory failure. Therefore, it is considered a new and effective noninvasive ventilation mode. There are many studies on the rational use, efficacy, and safety of noninvasive high-frequency oscillatory ventilation in neonates around the world. This article reviews the advances in the clinical studies on noninvasive high-frequency oscillatory ventilation in neonates.

Survey of noninvasive respiratory support practices in Canadian neonatal intensive care units

AIM

To evaluate practice variation with respect to noninvasive respiratory support (NRS) use across Canadian neonatal intensive care units (NICUs).

METHODS

A web-based survey was sent to all site investigators of the 30 level 3 NICUs participating in the Canadian Neonatal Network. The survey inquired about the use of five commonly described NRS modes. In addition, the presence and adherence to local guidelines were ascertained. Descriptive analyses were performed to identify variations in practice.

RESULTS

In total, 28 (93%) of the 30 tertiary NICUs responded to the survey. Continuous positive airway pressure (CPAP) was employed universally (100%). High-flow nasal cannula (HFNC) was used in 89% of NICUs, biphasic CPAP in 79% and nasal intermittent positive pressure ventilation (NIPPV) in 54%, and nasal high-frequency ventilation was used in 18% of units. Only 61% of all NRS use was guided by local policies, with the lowest being for HFNC (36%). There was a wide range of settings employed and interfaces used for all NRS modes.

CONCLUSION

There are significant practice variations in NRS use across Canadian NICUs. Further research is needed to evaluate the significance in relation to pulmonary outcomes to determine optimal NRS strategies.

Non-invasive high-frequency oscillatory ventilation in neonates: review of physiology, biology and clinical data

Non-invasive high-frequency oscillatory ventilation (NHFOV) consists of the application of a bias flow generating a continuous distending positive pressure with superimposed oscillations, which have constant frequency and active expiratory phase. NHFOV matches together the advantages of high-frequency ventilation (no need for synchronisation, high efficacy in removing CO₂) and nasal continuous positive airway pressure (CPAP) (non-invasive interface, increase in functional residual capacity allowing oxygenation to improve). There is enough clinical expertise demonstrating that NHFOV may be tried in some selected cases, in whom CPAP or conventional non-invasive ventilation have failed. Nonetheless, there are no clear data about its clinical usefulness and there is a need for randomised controlled studies. Our purpose is to review the physiology and biological effects of NHFOV, to present the current clinical evidence on its use, to provide some guiding principles to clinicians and suggest directions for further research.

High-frequency ventilation for non-invasive respiratory support of neonates

Non-invasive respiratory support is increasingly used in lieu of intubated ventilator support for the management of neonatal respiratory failure, particularly in very low birth weight infants at risk for bronchopulmonary dysplasia. The optimal approach and mode for non-invasive support remains uncertain. This article reviews the application of high-frequency ventilation for non-invasive respiratory support in neonates, including basic science studies on mechanics of gas exchange, animal model investigations, and a review of current clinical use in human neonates.

Nasal intermittent positive pressure ventilation in preterm infants: Equipment, evidence, and synchronization

The use of nasal intermittent positive pressure ventilation (NIPPV) as respiratory support for preterm infants is well established. Evidence from randomized trials indicates that NIPPV is advantageous over continuous positive airway pressure (CPAP) as post-extubation support, albeit with varied outcomes between NIPPV techniques. Randomized data comparing NIPPV with CPAP as primary support, and for the treatment of apnea, are conflicting. Intrepretation of outcomes is limited by the multiple techniques and devices used to generate and deliver NIPPV. This review discusses the potential mechanisms of action of NIPPV in preterm infants, the evidence from clinical trials, and summarizes recommendations for practice.