Continuous Positive Airway Pressure Level Research Articles

Effect of different CPAP levels on ultrasound-assessed lung aeration and gas exchange in neonates

BackgroundRespiratory distress syndrome (RDS) and transient tachypnoea (TTN) are the two commonest neonatal respiratory disorders. The optimal continuous positive airway pressure (CPAP) to treat them is unknown. We aim to clarify the effect of different CPAP levels on lung aeration and gas exchange in patients with RDS and TTN.MethodsProspective, observational, pragmatic, physiological cohort study. CPAP was sequentially increased from 4 to 6 and 8 cmH2O and backwards, with interposed wash-out periods. Lung aeration was assessed with a validated neonatal lung ultrasound score. Gas exchange was non-invasively evaluated with transcutaneous monitoring. Ultrasound score and PtcO2/FiO2 ratio were the co-primary outcomes. PtcCO2 and other oxygenation metrics were the secondary outcomes.Results30 neonates with RDS and 30 with TTN were studied. Each CPAP increment significantly (overall always p < 0.001) improved both lung aeration and oxygenation, but the increase from 6 to 8 cmH2O achieved a small absolute benefit. In RDS patients, the absolute improvements were small and the diagnosis of TTN was significantly associated with greater improvement of lung aeration (β= -1.4 (95%CI: -2.4; -0.3), p = 0.01) and oxygenation (β = 39.6 (95%CI: 4.1; 75.1), p = 0.029). Aeration improved in 16 (53.3%) and 27 (90%) patients in the RDS and TTN groups, respectively (p = 0.034). Lung aeration showed significant hysteresis in TTN patients. Secondary outcomes gave similar results.ConclusionsIncreasing CPAP from 4 to 8 cmH2O improves ultrasound-assessed lung aeration and oxygenation in RDS and TTN. The absolute improvements are small when CPAP is beyond 6 cmH2O or for RDS patients.

Formulas to predict continuous positive airway pressure level using a home auto-adjusting device for obstructive sleep apnea treatment.

To develop equations to predict therapeutic continuous positive airway pressure (CPAPT) based on home-based CPAP titration, including the type of interface used. Retrospective study conducted in adult patients with obstructive sleep apnea (OSA) who used home-based autoCPAP titration (AutoSet S10, ResMed®). CPAPT was obtained manually through a visual analysis of autoCPAP data (CPAPV) and automatically using the 95th percentile pressure (CPAPP95). Multiple linear regression and K-fold cross-validation were applied. Independent variables were AHI, neck circumference (NC), BMI, and mask. Two formulas were generated based on mask and the Miljeteig and Hoffstein formula. We included 702 patients (174 women), median age, BMI and AHI of 58 years, 32kg/m2 and 32 ev/h, respectively. Predictors for CPAPv (M1) were BMI, NC, AHI and type of interface (R2: 0.19); and for CPAPP95 (M2), BMI, AHI and mask (R2: 0.09). Error and precision between the formulas and CPAPT were: 0 (CPAPV/CPAPP95), and - 3.2 to 3.2 (CPAPV) and - 4 to 4cm H2O (CPAPP95). CPAPV was higher with oronasal mask (10 vs. 9cm H2O, p < 0.01). Accuracy defined as; a difference ± 2 cm H2O between estimated CPAP and CPAPT was greater in M1 than in M2 (79% vs. 64%, p < 0.01). In both models, calculated error was close to zero. CPAPV (± 3.2cm H2O) showed more precision than CPAPP95 (± 4cm H2O). With M1 (CPAPV), 79% of patients could start CPAP with reasonable accuracy (error of ± 2cm H2O).

Repeated daily exposure to mild intermittent hypoxia increases the auditory and tactile arousal thresholds in patients with obstructive sleep apnea

Background: Exposure to repeated daily mild intermittent hypoxia (MIH) leads to an increase in upper airway patency coupled to a reduction in continuous positive airway pressure (CPAP) used to treat obstructive sleep apnea (OSA). These modifications are associated with an increase in CPAP adherence. In addition, treatment with MIH might impact other factors that influence adherence, including the arousal threshold. Indeed, we showed that exposure to MIH resulted in an increased respiratory arousal threshold. Objective: The present study was designed to extend these findings to determine if increases in the arousal threshold to auditory or tactile stimuli increase after exposure to MIH. These modifications could be advantageous and contribute to increases in CPAP adherence that were previously observed. Methods: A total of 19 participants with OSA, with an apnea-hypopnea index &gt; 5 (AHI), were recruited and randomly allocated to two groups. One group was exposed to repeated daily MIH, while the other group was exposed to sham MIH. Participants in the MIH group [n = 9; age - 45.22 ± 8.66 years; body mass index - 31.59 ± 5.49 kg/m2; apnea hypopnea index (AHI) - 58.39 ± 17.57 events/hr.] were exposed to twelve 2-minute hypoxic episodes (PETO2 ~ 50 mmHg) separated by 2- minute normoxic intervals (with PETCO2 sustained 2 mmHg above baseline) for 15 days. Participants in the sham group [n = 10; age - 47.1 ± 9.48 years; body mass index - 34.79 ± 4.57 kg/m2; AHI - 70.18 ± 22.42 events/hr.] were exposed to compressed room air. Arousal thresholds were measured objectively during sleep using auditory (ear inserted headphones) (MIH - n = 5; Sham -n = 9) and tactile (digital pressure algometer) (MIH - n = 8; Sham - n = 10) stimulation, while participants were treated with therapeutic levels of CPAP. These measures were obtained during sleep studies completed before exposure to MIH or sham MIH, and 4 days, 4 and 8 weeks after exposure. Results: Body mass index (p = 0.18), age (p = 0.66) and AHI (p = 0.22) were similar between the two groups prior to therapy. A significant increase in the tactile threshold measured on the left side was observed 4 days [1.89 ± 1.08 vs. 2.81 ± 1.23 pound-force (Ibf), p = 0.005] and 4 weeks (1.89 ± vs 1.08 ± 1.48 Ibf, p = 0.024) after therapy in the MIH group. This improvement was not evident after 8 weeks (p = 0.16). No difference in the tactile threshold was evident at any point following exposure to sham MIH (P &gt; 0.128 for all comparisons). There was a significant increase in the auditory threshold immediately after treatment with MIH compared to baseline (54.00 ± 2.24 vs. 67.00 ± 11.51 dB, P = 0.031), which was not evident 4 or 8 weeks after therapy. A significant correlation between the auditory and tactile arousal thresholds was also evident when all time points were included (R = 0.48, P = 0.015). The auditory threshold values were similar at all time points in the Sham MIH group (P &gt; 0.52 for all comparisons). Conclusion: Our results suggest that exposure to repeated daily exposure to mild intermittent hypoxia results in an increase in the auditory and tactile arousal threshold level immediately after exposure to MIH, which was sustained for 4 weeks in the case of the tactile threshold. The increase in the auditory and arousal threshold could contribute to the improved adherence to CPAP that we previously reported was evident after repeated daily exposure to MIH. I01CX000125, IK6CX002287, R01HL142757, R56HL142757. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

CPAP may promote an endothelial inflammatory milieu in sleep apnoea after coronary revascularization

Continuous positive airway pressure (CPAP) has failed to reduce cardiovascular risk in obstructive sleep apnoea (OSA) in randomized trials. CPAP increases angiopoietin-2, a lung distension-responsive endothelial proinflammatory marker associated with increased cardiovascular risk. We investigated whether CPAP has unanticipated proinflammatory effects in patients with OSA and cardiovascular disease. Patients with OSA (apnoea-hypopnea index [AHI] ≥15 events/h without excessive sleepiness) in the Randomized Intervention with CPAP in Coronary Artery Disease and OSA study were randomized to CPAP or usual care following coronary revascularization. Changes in plasma levels of biomarkers of endothelial (angiopoietin-2, Tie-2, E-selectin, vascular endothelial growth factor [VEGF-A]) and lung epithelial (soluble receptor of advanced glycation end-products [sRAGE]) function from baseline to 12-month follow-up were compared across groups and associations with cardiovascular morbidity and mortality assessed. Patients with OSA (n=189; 84% men; age 66±8 years, BMI 28±3.5kg/m2, AHI 41±23 events/h) and 91 patients without OSA participated. Angiopoietin-2 remained elevated whereas VEGF-A declined significantly over 12 months in the CPAP group (n=91). In contrast, angiopoietin-2 significantly declined whereas VEGF-A remained elevated in the usual care (n=98) and OSA-free groups. The changes in angiopoietin-2 and VEGF-A were significantly different between CPAP and usual care, whereas Tie-2, sRAGE and E-selectin were similar. Greater 12-month levels of angiopoietin-2 were associated with greater mortality. Greater CPAP levels were associated with worse cardiovascular outcomes. Greater CPAP levels increase proinflammatory, lung distension-responsive angiopoietin-2 and reduce cardioprotective angiogenic factor VEGF-A compared to usual care, which may counteract the expected cardiovascular benefits of treating OSA. National Institutes of Health/National Heart, Lung, and Blood Institute; Swedish Research Council; Swedish Heart-Lung Foundation; ResMed Foundation.

Evaluation of a respiratory care protocol including less invasive surfactant administration in preterm infants.

Respiratory care protocol including less invasive śsurfactant administration (LISA) in ≤29 weeks' gestational age (GA) infants introduced in October 2018. Retrospective study of infants admitted on continuous positive airway pressure (CPAP) October 2018 to December 2021. Maternal and neonatal variables were compared between infants managed on CPAP with and without LISA. Infants who received LISA and subsequently required mechanical ventilation (MV) within 72 h of life (HOL) [LISA failure (LF)] were compared with those who required no MV [LISA success (LS)]. 249 infants were admitted on CPAP, 5 were intubated prior to LISA, 143 required LISA and 101 remained on CPAP without surfactant. Of those receiving LISA, 108 were LS and 35 were LF. Compared to LS, LF infants were of lower GA and birth weight, required higher fractional inspired oxygen (FiO2), and CPAP level at birth, admission, one HOL, and an hour after LISA. Moreover, LF infants had higher mortality and morbidity. Together GA ≤ 25 weeks' and FiO2 ≥ 0.3 an hour after LISA best predicted LF. Over 80% of infants admitted on CPAP avoided MV within 72 HOL. Early predictors of LF provide targets for future interventions to decrease need for MV in preterm infants. Less invasive surfactant administration (LISA) decreases the need for mechanical ventilation (MV) and improves outcomes. However, some infants require MV within 72 h of life (HOL) despite LISA (LISA failure). Over 80% of ≤29 weeks' gestational age (GA) infants can be successfully managed on CPAP with or without surfactant in the first 72 HOL. A combination of factors including ≤25 weeks' GA and fraction of inspired oxygen ≥0.3 an hour after LISA predict LISA failure. Evaluation of a noninvasive respiratory support strategy including LISA provides targets for intervention to decrease need for MV in preterm infants.

Measuring Expiratory Diaphragm Activity: An Electrifying Tool to Guide Positive End-Expiratory Pressure Strategy in Critically Ill Children?

Measuring Expiratory Diaphragm Activity: An Electrifying Tool to Guide Positive End-Expiratory Pressure Strategy in Critically Ill Children?

Performance of helmet CPAP using different configurations: Turbine-driven ventilators vs Venturi devices

BackgroundTraditionally, Venturi-based flow generators have been preferred over mechanical ventilators to provide continuous positive airway pressure (CPAP) through the helmet (h-CPAP). Recently, modern turbine-driven ventilators (TDVs) showed to be safe and effective in delivering h-CPAP. We aimed to compare the pressure stability during h-CPAP delivered by Venturi devices and TDVs and assess the impact of High Efficiency Particulate Air (HEPA) filters on their performance. MethodsWe performed a bench study using an artificial lung simulator set in a restrictive respiratory condition, simulating two different levels of patient effort (high and low) with and without the interposition of the HEPA filter. We calculated the average of minimal (Pmin), maximal (Pmax) and mean (Pmean) airway pressure and the time product measured on the airway pressure curve (PTPinsp). We defined the pressure swing (Pswing) as Pmax - Pmin and pressure drop (Pdrop) as End Expiratory Pressure - Pmin. ResultsPswing across CPAP levels varied widely among all the tested devices. During “low effort”, no difference in Pswing and Pdrop was found between Venturi devices and TDVs; during high effort, Pswing (p<0.001) and Pdrop (p<0.001) were significantly higher in TDVs compared to Venturi devices, but the PTPinsp was lower (1.50 SD 0.54 vs 1.67 SD 0.55, p<0.001). HEPA filter addition almost doubled Pswing and PTPinsp (p<0.001) but left unaltered the differences among Venturi and TDVs systems in favor of the latter (p<0.001). ConclusionsTDVs performed better than Venturi systems in delivering a stable positive pressure level during h-CPAP in a bench setting.

Impact of sedation, body position change and continuous positive airway pressure on distribution of ventilation in healthy foals.

This study aimed to compare the distribution of ventilation measured by electrical impedance tomography (EIT), in foals under varying clinical conditions of sedation, postural changes, and continuous positive airway pressure (CPAP). To support the interpretation of EIT variables, specific spirometry data and F-shunt calculation were also assessed. Six healthy Thoroughbred foals were recruited for this sequential experimental study. EIT and spirometry data was recorded: (1) before and after diazepam-sedation, (2) after moving from standing to right lateral recumbency, (3) in dorsal recumbency during no CPAP (CPAP0) and increasing levels of CPAP of 4, 7, and 10 cmH2O (CPAP4, 7, 10, respectively). Ventral to dorsal (COVVD) and right to left (COVRL) center of ventilation, silent spaces, tidal impedance variation, regional ventilation distribution variables and right to left lung ventilation ratio (R:L) were extracted. Minute ventilation was calculated from tidal volume (VT) and respiratory rate. F-Shunt was calculated from results of arterial blood gas analysis. Statistical analysis was performed using linear mixed effects models (significance determined at p < 0.05). (1) Respiratory rate was lower after sedation (p = 0.0004). (2) In right lateral recumbency (compared to standing), the COVVD (p = 0.0012), COVRL (p = 0.0057), left centro-dorsal (p = 0.0071) and dorsal (p < 0.0001) regional ventilation were higher, while the right ventral (p = 0.0016) and dorsal (p = 0.0145) regional ventilation, and R:L (p = 0.0017) were lower. (3) Data of two foals for CPAP10 was excluded from statistical analysis due to prolonged apnea. Stepwise increase of CPAP led to increases of COVVD (p = 0.0028) and VT (p = 0.0011). A reduction of respiratory rate was detected with increasing CPAP levels (p < 0.0001). (1) In healthy foals, diazepam administration did not alter distribution of ventilation or minute ventilation, (2) lateral recumbency results in collapse of dependent areas of the lung, and (3) the use of CPAP in dorsal recumbency at increasing pressures improves ventilation in dependent regions, suggesting improvement of ventilation-perfusion mismatch.

Continuous Positive Airway Pressure for the Treatment of Supine Hypertension and Orthostatic Hypotension in Autonomic Failure.

Supine hypertension affects most patients with orthostatic hypotension (OH) due to autonomic failure, but it is often untreated for fear of worsening OH. We hypothesized that increasing intrathoracic pressure with continuous positive airway pressure (CPAP) had a Valsalva-like blood-pressure-lowering effect that could be used to treat nocturnal supine hypertension in these patients, while reducing nocturnal pressure diuresis and improving daytime OH. In Protocol 1, we determined the acute hemodynamic effects of increasing levels of CPAP (0, 4, 8, 12, and 16 cm H2O, 3 minutes each) in 26 patients with autonomic failure and supine hypertension studied while awake and supine. In Protocol 2 (n=11), we compared the effects of overnight therapy with CPAP (8-12 cm H2O for 8 hours) versus placebo on nocturnal supine hypertension, nocturnal diuresis and daytime OH in a 2-night crossover study. In Protocol 1, acute CPAP (4-16 cm H2O) decreased systolic blood pressure in a dose-dependent manner (maximal drop 22±4 mmHg with CPAP 16) due to reductions in stroke volume (-16+3%) and cardiac output (-14±3%). Systemic vascular resistance and heart rate remained unchanged. In Protocol 2, overnight CPAP lowered nighttime systolic blood pressure (maximal change -23±5 versus placebo -1±7 mmHg; P=0.023) and was associated with lower nighttime diuresis (609±84 versus placebo 1004±160 mL; P=0.004) and improved morning orthostatic tolerance (AUC upright SBP 642±121 versus placebo 410±109 mmHg*min; P=0.014). CPAP is a novel nonpharmacologic approach to treat the supine hypertension of autonomic failure while improving nocturia and daytime OH. URL: https://www. gov; Unique identifier: NCT03312556.

Nasal pillow vs. standard nasal mask for treatment of OSA: a systematic review and meta-analysis.

The purpose of this study was to compare the effectiveness of nasal pillows with standard nasal masks in the treatment of patients with obstructive sleep apnea (OSA). A digitalized search was carried out in four different databases including PubMed, Scopus, EMBASE, and CENTRAL using relevant keywords along with a manual search in relevant journals. All comparative studies comparing outcomes of using a nasal pillow with the use of standard nasal masks for continuous positive airway pressure (CPAP) treatment in patients with OSA were included. The qualitative analysis was carried out by tabulating the demographic data. The quantitative data were subjected to meta-analysis. The quality of comparative studies (both retrospective and prospective cohorts) was evaluated using New-castle Ottawa scale (NOS). A total of 14 studies (eight prospective and six retrospective) were included in the review. Of them, five studies were randomized and were of cross-over study design. No significant differences were observed in achieved CPAP and residual apnea-hypopnea index (AHI) levels between the nasal pillow and nasal mask with SMD - 0.05 95% CI [- 0.18, 0.09], p = 0.50 and SMD - 0.13 95% CI [- 0.28, 0.03], p = 0.12, respectively. However, nasal pillow usage was associated with better CPAP adherence with a difference of only + 0.29min/night as compared to a standard nasal mask, with SMD 0.29 95% CI [0.07, 0.50], p = 0.009. Nasal pillow and standard nasal mask were equally effective in terms of residual AHI level and achieved similar therapeutic CPAP pressures. However, the difference in CPAP adherence between groups, though statistically significant, is of questionable clinical significance.

Use of ventilation/perfusion mismatch to guide individualised CPAP level selection in preterm infants: a feasibility trial

ObjectiveTo measure within-subject changes in ventilation/perfusion (V′/Q′) mismatch in response to a protocol of individualised nasal continuous positive airway pressure (CPAP) level selection.DesignSingle-arm, non-randomised, feasibility trial.SettingThree centres in the Children’s...

Pleural pressure during sleep in Marfan syndrome: details about the CPAP effect.

Pleural pressure during sleep in Marfan syndrome: details about the CPAP effect.

Fraction of apnea is associated with the required continuous positive airway pressure level and reflects upper airway collapsibility in patients with obstructive sleep apnea.

We aimed to determine whether the fraction of apnea (Fapnea) could be used as an alternative index to reflect upper airway collapsibility. We retrospectively recruited 161 patients (16 women, mean age 47.8 years, body mass index [BMI] 28.0 kg/m2, and apnea-hypopnea index 46.4 events/h) with moderate to severe obstructive sleep apnea who had undergone nasal continuous positive airway pressure (CPAP) titration. Fapnea is defined as the percentage of apneic events relative to the total number of apneic and hypopneic events during sleep in a supine position on diagnostic polysomnography. We randomly split the data (70/30) into the development and validation datasets. In the development dataset, we conducted a multiple regression analysis to assess the association of variables, including age, sex, BMI, supine rapid eye movement (REM) sleep apnea-hypopnea index, and apnea with a CPAP level during supine REM sleep (REM_CPAP). Moreover, we developed an equation for predicting the CPAP level. Thereafter, we evaluated the correlation between the actual CPAP level and the value calculated using the model. BMI and Fapnea were the only significant factors that predicted the REM_CPAP level (adjusted r = .60, P < .001) in the development dataset. The validation data revealed a significant correlation between the actual and predicted CPAP levels (r = .69, P < .0001). We observed similar associations during supine non-REM sleep. Fapnea could significantly predict the CPAP levels during both REM and non-REM sleep, which likely reflects the upper airway collapsibility, independent of the BMI. Nakayama H, Takei Y, Kobayashi M, Yanagihara M, Inoue Y. Fraction of apnea is associated with the required continuous positive airway pressure level and reflects upper airway collapsibility in patients with obstructive sleep apnea. J Clin Sleep Med. 2022;18(5):1243-1249.

Noninvasive Ventilation and Exogenous Surfactant in Times of Ever Decreasing Gestational Age: How Do We Make the Most of These Tools?

Noninvasive Ventilation and Exogenous Surfactant in Times of Ever Decreasing Gestational Age: How Do We Make the Most of These Tools?

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Prediction of Mandibular Advancement Device Response Using CPAP Pressure in Different Polysomnographic Phenotypes.

ObjectiveBoth continuous positive airway pressure (CPAP) pressure and polysomnographic phenotypes have been associated with mandibular advancement device (MAD) treatment response, but the precise relationship has not been fully elucidated. We hypothesized that utilizing CPAP pressure would predict the MAD response in treatment-naïve patients with moderate-severe obstructive sleep apnea (OSA), and the MAD response would be associated with two polysomnographic phenotypes, including sleep stage dependency and positional dependency.MethodsOSA treatment-naïve patients with an apnea-hypopnea index (AHI) ≥15/h who declined CPAP treatment and received MAD treatment for 3–6 months were enrolled. The MAD treatment response was defined as 1) residual AHI under MAD (AHIMAD) <5/h and 2) AHIMAD <10/h. Logistic regression was applied to identify the association between CPAP pressure and MAD treatment responders. The predictability of the MAD responder status utilizing CPAP pressure was assessed with the area under the receiver operating characteristic (AUROC).ResultsA total of 128 enrolled patients (AHI ≥30/h in 74.2%) were recruited, of whom 119 patients and 80 patients were included for analysis of sleep stage and positional dependency, respectively. REM-predominant OSA had lower AHI than stage-independent OSA, while the supine-predominant phenotype had lower anthropometrics than the nonpositional-dependent phenotype. The response rates for AHIMAD <5/h and AHIMAD <10/h were 25.8% and 48.4%, respectively. Lower anthropometrics, baseline AHI, and supine predominance were associated with the responder status, while CPAP pressure was an independent predictor. The AUROCs for the prediction of AHIMAD <5/h and AHIMAD <10/h responders were 0.635 and 0.664, respectively. Utilizing a CPAP level >14 cmH2O as the cutoff to predict criterion 1 and 2 nonresponders, the sensitivity was 93.9% and 95.2%, respectively.ConclusionIn treatment-naïve patients with moderate-severe OSA, the supine-predominant phenotype and lower CPAP pressure were associated with the MAD response, while the sleep stage dependency phenotype was not. Utilization of a CPAP level >14 cmH2O could be a sensitive measure to identify nonresponders.

Positive Airway Pressure at Extubation Minimizes Subglottic Secretion Leak In Vitro.

Accumulated secretion above the endotracheal tube cuff can be aspirated during extubation after deflation. The possible techniques for minimizing pulmonary aspiration from subglottic secretion during extubation have not been well explored. This study aimed to determine the effect of different extubation techniques on secretion leakage. An endotracheal tube was placed in a tube mimicking an airway. We measured the leak volume of water or artificial sputum of different viscosities with three extubation techniques—negative pressure with suctioning; positive pressure with a resuscitator; and continuous positive airway pressure set at 5, 10, and 20 cm H2O. Extubation with continuous positive airway pressure resulted in lower secretion leakage than that with negative pressure with suctioning and positive pressure with a resuscitator. Increasing the continuous positive airway pressure level decreased secretion leakage volume during extubation. We further determined a correlation of leak volume with sputum viscosity. Continuous positive airway pressure at 5 cm H2O produced lower volume secretion leakage than the other two techniques, even with higher secretion viscosity. Based on these results, using continuous positive airway pressure with a previous ventilator continuous positive airway pressure/positive end-expiratory pressure setting for extubation is recommended.

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

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

Protocol for a randomised controlled trial comparing two CPAP levels to prevent extubation failure in extremely preterm infants

IntroductionRespiratory distress syndrome is a complication of prematurity and extremely preterm infants born before 28 weeks’ gestation often require endotracheal intubation and mechanical ventilation. In this high-risk population, mechanical ventilation...

Bilevel positive airway pressure for neonates - a short report.

Invasive mechanical ventilation in the neonatal setting can be life-saving, but may lead to chronic respiratory morbidity. As a consequence, there has been a focus on using non-invasive ventilation techniques (NIV). One NIV mode is bilevel continuous positive airway pressure (BiPAP), during which two alternating levels of pressure are delivered: a lower/baseline pressure (usually 4-6 cm H2 O) and an upper pressure (usually 3-5 cm H2 O above the lower continuous positive airway pressure (CPAP) level) which is delivered at a set rate with a specified inspiratory time (usually 0.5-1 seconds) (1).