Influence of nose and mouth leaks on peripheral oxygen saturation during continuous positive airway pressure in neonates

Non-Invasive Ventilatory Support in Preterm Neonates in the Delivery Room and the Neonatal Intensive Care Unit: A Short Narrative Review of What We Know in 2024

BACKGROUND

Guidelines recommend non-invasive ventilatory (NIV) support as first-line respiratory support mode in preterm infants as NIV is superior to intubation and mechanical ventilation in preventing death or bronchopulmonary dysplasia. However, with an ever-expanding variety of NIV modes available, there is much debate about which NIV modality should ideally be used, how, and when. The aims of this work were to summarise the evidence on different NIV modalities for both primary and secondary respiratory support: nCPAP, nasal high-flow therapy (nHFT), and nasal intermittent positive airway pressure ventilation (nIPPV), bi-level positive airway pressure (BiPAP), nasal high-frequency oscillatory ventilation (nHFOV), and nasally applied, non-invasive neurally adjusted ventilatory assist (NIV-NAVA) modes, with particular focus on their use in preterm infants.

SUMMARY

This is a narrative review with reference to published guidelines by European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update. nCPAP is currently the most commonly used primary and secondary NIV modality for premature infants. However, there is increasing evidence on the superiority of nIPPV over nCPAP. No beneficial effect was found for BiPAP over nCPAP. For the use of nHFT, nHFOV, and NIV-NAVA, more studies are needed to establish their place in neonatal respiratory care.

KEY MESSAGES

The superiority of nIPPV over nCPAP needs to be confirmed by contemporaneous trials comparing nCPAP to nIPPV at comparable mean airway pressures. Future trials should study NIV modalities in preterm infants with comparable respiratory pathology and indications, at comparable pressure settings and with different modes of synchronisation. Importantly, future trials should not exclude infants of the smallest gestational ages.

Satisfaction of Health Professionals Regarding the Short Binasal Prong Used as a Non-Invasive Ventilation Interface in Neonatology

Purpose

To evaluate the health professionals' satisfaction regarding the short binasal prong used in Neonatal Intensive Care Units (NICU), evaluate the difficulties related to its use, and present possible improvements in the design of this device.

Patients and Methods

Observational, cross-sectional study with prospective data collection carried out in the NICU of a public hospital in southern Brazil. This research was presented into two stages. In the first stage, the Quebec User Evaluation of Satisfaction with Assistive Technology was applied with 90 health professionals to evaluate the satisfaction regarding the short binasal prong. In the second stage, the health professional's experiences and difficulties in using the binasal prongs in 14 newborns (NBs) that required non-invasive ventilation was collected. The short binasal prongs used was the Fanem® brand and the CPAP circuit was Gabisa Medical International (GMI®). Finally, improvements and recommendations were presented to optimize the device's design.

Results

The mean score of the health professionals' satisfaction with short binasal prongs was 3.8 ± 0.6. Ease of adjustment (3.27) and dimensions (3.62) variables had the worst scores. The main difficulties pointed out by health professionals were: circuit disconnection (57.1%), the size of the prong did not correspond to NBs' anatomical characteristics (35.7%), air leakage (21.4%), and difficulty in fixing and positioning the prong in the NB (14.28%). The improvements suggested were: appropriate prong sizes based on the anatomical characteristics of the NBs; adjustable distance between insertion and base catheters; manufactured with malleable material, however not easily foldable; curved and adjustable insertion catheters and functional system of tracheas' connection.

Conclusion

The dissatisfaction of health professionals with the dimensions and prongs adjustments and the difficulties faced in clinical practice indicate the need for improvements in these interfaces. The recommendations presented in this study may contribute to optimizing the design of the binasal prong in the future.

Interface leakage during neonatal CPAP treatment: a randomised, cross-over trial

OBJECTIVE

To determine leakage for two neonatal continuous positive airway pressure (CPAP) interfaces and evaluate leak-corrective manoeuvres.

DESIGN

The ToNIL (Trial of NCPAP Interface Leakage) study was a randomised, clinical, cross-over trial with data collection between August 2018 and October 2019. The primary outcome was blinded to the treating staff.

SETTING

One secondary, 8-bed neonatal intensive care unit (NICU) and three larger (>15 beds), academic NICU referral centres.

PATIENTS

Newborn infants with CPAP were screened (n=73), and those with stable spontaneous breathing, low oxygen requirement, postmenstrual age (PMA) over 28 weeks and no comorbidities were eligible. In total, 50 infants were included (median PMA 33 completed weeks).

INTERVENTIONS

Leakage was measured for both prongs and nasal mask, before and after leak-corrective manoeuvres. Interface application was performed in a randomised order by a nurse, blinded to the measured leakage.

MAIN OUTCOME MEASURES

30 s average leakage, measured in litres per minute (LPM).

RESULTS

Analyses showed a significantly lower leakage (mean difference 0.86 LPM, 95% CI 0.07 to 1.65) with prongs (median 2.01 LPM, IQR 1.00-2.80) than nasal mask (median 2.45 LPM, IQR 0.99-5.11). Leak-corrective manoeuvres reduced leakage significantly for both prongs (median 1.22 LPM, IQR 0.54-1.87) and nasal mask (median 2.35 LPM, IQR 0.76-4.75).

CONCLUSIONS

Large leakages were common for both interfaces, less with prongs. Simple care manoeuvres reduced leakage for both interfaces. This is the first report of absolute leakage for nasal interfaces and should encourage further studies on leakage during CPAP treatment.

Early extubation to noninvasive respiratory support of former preterm lambs improves long-term respiratory outcomes

Invasive mechanical ventilation (IMV) and exposure to oxygen-rich gas during early postnatal life are contributing factors for long-term pulmonary morbidities faced by survivors of preterm birth and bronchopulmonary dysplasia. The duration of IMV that leads to long-term pulmonary morbidities is unknown. We compared two durations of IMV (3 h vs. 6 days) during the first 6-7 days of postnatal life in preterm lambs to test the hypothesis that minimizing the duration of IMV will improve long-term respiratory system mechanics and structural outcomes later in life. Moderately preterm (∼85% gestation) lambs were supported by IMV for either 3 h or 6 days before weaning from all respiratory support to become former preterm lambs. Respiratory system mechanics and airway reactivity were assessed monthly from 1 to 6 mo of chronological postnatal age by the forced oscillation technique. Quantitative morphological measurements were made for smooth muscle accumulation around terminal bronchioles and indices of alveolar formation. Minimizing IMV to 3 h led to significantly better (P < 0.05) baseline respiratory system mechanics and less reactivity to methacholine in the first 3 mo of chronological age (2 mo corrected age), significantly less (P < 0.05) accumulation of smooth muscle around peripheral resistance airways (terminal bronchioles), and significantly better (P < 0.05) alveolarization at the end of 5 mo corrected age compared with continuous IMV for 6 days. We conclude that limiting the duration of IMV following preterm birth of fetal lambs leads to better respiratory system mechanics and structural outcomes later in life.

Differential impact of flow and mouth leak on oropharyngeal humidification during high-flow nasal cannula: a neonatal bench study

BACKGROUND

Heated humidification is paramount during neonatal high-flow nasal cannula (HFNC) therapy. However, there is little knowledge about the influence of flow rate and mouth leak on oropharyngeal humidification and temperature.

METHODS

The effect of the Optiflow HFNC on oropharyngeal gas conditioning was investigated at flow rates of 4, 6 and 8 L min^-1 with and without mouth leak in a bench model simulating physiological oropharyngeal air conditions during spontaneous breathing. Temperature and absolute humidity (AH) were measured using a digital thermo-hygrosensor.

RESULTS

Without mouth leak, oropharyngeal temperature and AH increased significantly with increasing flow (P < 0.001). Mouth leak did not affect this increase up to 6 L min^-1, but at 8 L min^-1, temperature and AH plateaued, and the effect of mouth leak became statistically significant (P < 0.001).

CONCLUSIONS

Mouth leak during HFNC had a negative impact on oropharyngeal gas conditioning when high flows were applied. However, temperature and AH always remained clinically acceptable.

Nasal high-frequency oscillatory ventilation impairs heated humidification: A neonatal bench study

OBJECTIVE

Nasal high-frequency oscillatory ventilation (nHFOV) is a novel mode of non-invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high-frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions.

METHODS

NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth. A digital thermo-hygro sensor measured oropharyngeal temperature (T) and humidity at various nHFOV frequencies (7, 10, 13 Hz), amplitudes (10, 20, 30 cmH₂ O), and inspiratory-to-expiratory (I:E) ratios (25:75, 33:66, 50:50), and also during nCPAP.

RESULTS

Relative humidity was always >99%, but nHFOV resulted in lower mean T and absolute humidity (AH) in comparison to nCPAP (P < 0.001). Specifically, decreasing the nHFOV frequency and increasing nHFOV amplitude caused a decline in T and AH (P < 0.001). Mean T and AH were highest during nCPAP (T 34.8 ± 0.6°C, AH 39.3 ± 1.3 g · m^-3 ) and lowest during nHFOV at a frequency of 7 Hz and an amplitude of 30 cmH₂ O (T 32.4 ± 0.3°C, AH 34.7 ± 0.5 g · m^-3 ). Increasing the I:E ratio also reduced T and AH (P = 0.03).

CONCLUSION

Intensified nHFOV settings with low frequencies, high amplitudes, and high I:E ratios may place infants at an increased risk of upper airway desiccation. Future studies should investigate strategies to optimize heated humidification during nHFOV.

Carbon dioxide washout during high flow nasal cannula versus nasal CPAP support: An in vitro study

OBJECTIVE

To compare CO₂ washout time at different levels of HFNC versus NCPAP in a premature infant lung model with simulated mouth-closed and mouth-open conditions using two sizes of nasal cannula and full- and half-prong HFNC insertion depths.

DESIGN/METHODS

A piston-cylinder lung simulator, having a fixed volume of 30 ml and a 4.8 ml dead space, simulated spontaneous breathing (6.5 ml tidal volume, 50 br/min, Ti = 0.5 sec). Two Fisher & Paykel™ cannulas (Fisher & Paykel Healthcare Ltd., Auckland, New Zealand) (2.8 and 3.2 mm O.D.) and two Infant-Flow™ (CareFusion, Yorba Linda, CA) NCPAP cannulas (3.4 and 4.1 mm O.D.) were applied to simulated airways having either 3.5 or 4.5 mm I.D. nares. Simulated mouth opening was a 5 mm I.D. side tap below the nasal interface. The lung was primed with 5% CO₂ . Washout times were determined at HFNC settings of 3, 4, 5, 6, and 8 L/min and NCPAP at 3, 4, 5, 6, and 8 cm H₂ O with simulated open and closed-mouth conditions and full- and half-inserted HFNC prongs.

RESULTS

Overall combined mean washout times for NCPAP with mouth-closed were significantly longer than HFNC over all five pressure and flow device settings by 16.2% (P < 0.001). CO₂ washout times decreased as flow or pressure device settings were increased. There were negligible differences in washout times between NCPAP and HFNC with mouth-open. Mouth-open washout times were significantly less than mouth-closed for all conditions. Overall closed-mouth washout times for HFNC half-prong insertion were longer than for full-prong insertion by 5.3% (P < 0.022).

CONCLUSIONS

Significantly improved CO₂ elimination using HFNC versus NCPAP should be a particularly important consideration in premature infants having very high dead space-to-tidal volume ratio compared to larger infants. Pediatr Pulmonol. 2017;52:792-798. © 2017 Wiley Periodicals, Inc.

Leakage in nasal high-frequency oscillatory ventilation improves carbon dioxide clearance-A bench study

OBJECTIVE

Nasal high frequency oscillatory ventilation (nHFOV) is a promising mode of non-invasive neonatal respiratory support. To combine the effects of nasal continuous positive airway pressure (nCPAP) and high frequency oscillatory ventilation, an oscillatory pressure waveform is superposed to a nCPAP via a nasal or nasopharyngeal interface. nHFOV has been described to facilitate carbon dioxide (CO₂ ) elimination compared to nCPAP. The influence of unintended leakage on CO₂ elimination has not been investigated in nHFOV before. We explored the effects of oral leakage on CO₂ elimination during nHFOV in a physical model of the neonatal respiratory system.

METHODS

A neonatal ventilator was connected to an airway- and lung model using binasal prongs as interface. The model comprised a continuous CO₂ influx. Alveolar CO₂ partial pressure was continuously measured. Gas flow rates and pressures were measured simultaneously at the prongs, pharynx, lung, and at the leakage. Effects of combined nasopharyngeal leakage (0, 5, or 10 L/min) on CO₂ elimination, gas flow rate and pressure were determined at various ventilation frequencies (6, 8, 10, and 12 Hz) and amplitudes (10%, 20%, and 30% of maximum ventilator performance) at a mean airway pressure of 10 cmH₂ O.

RESULTS

nHFOV with moderate leakage was more effective in CO₂ elimination than without leakage (P < 0.001) for all tested amplitudes and frequencies. Maximum leakage resulted in highly variable, partly ineffective CO₂ elimination.

CONCLUSIONS

A moderate oral leakage rather improves than impairs gas exchange during non-invasive ventilatory support with nHFOV. Pediatr Pulmonol. 2017;52:367-372. © 2016 Wiley Periodicals, Inc.

Influence of mouth opening on oropharyngeal humidification and temperature in a bench model of neonatal continuous positive airway pressure

Clinical studies show that non-invasive respiratory support by continuous positive airway pressure (CPAP) affects gas conditioning in the upper airways, especially in the presence of mouth leaks. Using a new bench model of neonatal CPAP, we investigated the influence of mouth opening on oropharyngeal temperature and humidity. The model features the insertion of a heated humidifier between an active model lung and an oropharyngeal head model to simulate the recurrent expiration of heated, humidified air. During unsupported breathing, physiological temperature and humidity were attained inside the model oropharynx, and mouth opening had no significant effect on oropharyngeal temperature and humidity. During binasal CPAP, the impact of mouth opening was investigated using three different scenarios: no conditioning in the CPAP circuit, heating only, and heated humidification. Mouth opening had a strong negative impact on oropharyngeal humidification in all tested scenarios, but heated humidification in the CPAP circuit maintained clinically acceptable humidity levels regardless of closed or open mouths. The model can be used to test new equipment for use with CPAP, and to investigate the effects of other methods of non-invasive respiratory support on gas conditioning in the presence of leaks.

Nasal high-frequency oscillation ventilation in neonates: a survey in five European countries

Nasal high-frequency oscillation ventilation (nHFOV) is a non-invasive ventilation mode that applies an oscillatory pressure waveform to the airways using a nasal interface. nHFOV has been shown to facilitate carbon dioxide expiration, but little is known about its use in neonates. In a questionnaire-based survey, we assessed nHFOV use in neonatal intensive care units (NICUs) in Austria, Switzerland, Germany, the Netherlands, and Sweden. Questions included indications for nHFOV, equipment used, ventilator settings, and observed side effects. Of the clinical directors of 186 NICUs contacted, 172 (92 %) participated. Among those responding, 30/172 (17 %) used nHFOV, most frequently in premature infants <1500 g (27/30) for the indication nasal continuous positive airway pressure (nCPAP) failure (27/30). Binasal prongs (22/30) were the most common interfaces. The median (range) mean airway pressure when starting nHFOV was 8 (6-12) cm H2O, and the maximum mean airway pressure was 10 (7-18) cm H2O. The nHFOV frequency was 10 (6-13) Hz. Abdominal distension (11/30), upper airway obstruction due to secretions (8/30), and highly viscous secretions (7/30) were the most common nHFOV side effects.

CONCLUSION

In a number of European NICUs, clinicians use nHFOV. The present survey identified differences in nHFOV equipment, indications, and settings. Controlled clinical trials are needed to investigate the efficacy and side effects of nHFOV in neonates.