Administration Of Continuous Positive Airway Pressure Research Articles

The Relationship between Leptin Levels and Continuous Positive Airway Pressure Treatment: A Cluster Analysis

Abstract Objective Leptin is an appetite-suppressing hormone released by adipose tissue that plays an important role in severe obstructive sleep apnea syndrome (OSAS). However, it is unclear whether leptin levels are a useful biomarker for this syndrome. The present study aimed to assess the effect of continuous positive airway pressure (CPAP) treatment on the syndrome according to leptin levels, using a cluster classification based on clinical features of the syndrome. Materials and Methods We performed a hierarchical cluster analysis of data from 97 OSAS patients diagnosed via polysomnography. We also evaluated the effect after 6 months of CPAP administration. Results Clusters 1 (49 patients; 50.5%) and 2 (6 patients; 6.2%) presented normal leptin levels, and clusters 3 (11 patients; 11.3%) and 4 (31 patients; 32%) presented high leptin levels. Clusters 3 and 4 presented different leptin levels, but the same degree of obesity. After treatment, the levels of excessive daytime sleepiness improved in all clusters. In Cluster 3, leptin levels were significantly reduced after treatment. Conclusion Using the conventional diagnostic method of the apnea-hypopnea index, it was not clear whether leptin is a useful biomarker for the CPAP treatment. However, it may be helpful for particular clusters, including obese women, and where particular populations require CPAP treatment.

Comparison of High Flow Nasal Cannula and Continuous Positive Airway Pressure in COVID-19 Patients With Acute Respiratory Distress Syndrome in Critical Care Unit: A Randomized Control Study.

Background and objective Acute hypoxic respiratory failure in coronavirus disease 2019 (COVID-19) pneumonia has been treated with oxygen delivered by oxygen masks and non-invasive ventilation (NIV) with continuous positive airway pressure (CPAP), and more recently with high-flow nasal cannula (HFNC) devices. There is a paucity of randomized controlled trials to compare the efficacy of CPAP with HFNC in COVID-19 pneumonia. We conceptualized a randomized control study to compare the efficacy of HFNC and CPAP in reducing the need for invasive mechanical ventilation, estimation of mechanical ventilation-free days, and risk of intubation in COVID-19 patients with hypoxic respiratory failure. Methodology One hundred consecutive patients who satisfied the inclusion criteria were included in the trial. The patients were then randomly allocated to receive either CPAP or HFNC with settings as per the study protocol. The patients were deemed to have achieved the study endpoint when they were intubated due to any reason or successfully weaned from NIV to conventional oxygen therapies. The number of patients who required invasive ventilation and the number of invasive ventilation-free days were recorded and analyzed. Results Nineteen (38%) patients in the CPAP group and 30 (60%) patients in the HFNC group required invasive mechanical ventilation and the difference was statistically significant (p = 0.03, 95%CI: 0.1829-0.9129). The median number of days free of invasive mechanical ventilation in the CPAP group (median=5 (interquartile range (IQR(=5,6)) was more than in the HFNC group (median=4 (IQR=3,4)) and this difference was statistically significant (p<0.000). The secondary analysis of risk evaluation for intubation done using the Cox regression model showed no significant factors that could have contributed to intubation in the study population. The Kaplan-Meyer curve was used to express the probability of a patient getting intubated and the calculated hazard ratio was 2.29. Conclusion The administration of CPAP significantly reduced the intubation rate and prolonged invasive mechanical ventilation-free period in COVID-19 patients with hypoxic respiratory failure. We also inferred a two-fold increase in the risk of intubation in patients receiving HFNC compared to CPAP.

Outcome of Continuous Positive Airway Pressure (CPAP) Administration in Delivery Room for Neonates with ≧35 Weeks of Gestational Age with Respiratory Distress: A Randomized Control Trial in a Tertiary Care Hospital

The sixth edition of Neonatal Resuscitation program (NRP 2011) recommends the use of delivery room Continuous Positive Airway Pressure (DR CPAP) for neonates with respiratory distress in the delivery room irrespective of gestational age. However, there is no convincing evidence of benefit of DR CPAP amongst late preterm and term neonates. Methodology This single center, open label, randomized control trial was carried out in a tertiary care teaching hospital. Neonates delivered with GA ≧ 35 weeks developing labored breathing in the delivery room or requiring free flow oxygen to maintain SPO2 in target range were randomized to receive DR CPAP or free flow oxygen (DR FFO). The early neonatal outcome in the DR, and for those requiring NICU admission, was recorded. Results 131 neonates were enrolled in the study, 62 (47.32 %) neonates were randomized to DR CPAP while 69 (52.67 %) to DR FFO group. There was no statistically significant difference observed among neonates from both groups who improved in the DR ( P value:.55) or those shifted to NICU in view of respiratory distress ( P value:.54). There was no significant difference in the modified Downes score amongst 2 groups at the time of NICU admission ( P value:.39). Conclusion This randomized control trial showed no significant difference in the delivery room or early neonatal outcome after the administration of DR CPAP or FFO amongst neonates with gestational age ≧ 35 weeks presenting with respiratory distress. Robust evidence needs to be generated to support the current recommendation of administering DR CPAP irrespective of gestation age.

Early lung ultrasound score to predict noninvasive ventilation needing in neonates from 33 weeks of gestational age: A multicentric study.

To propose an early lung ultrasound (LUS) score for the prediction of the need for respiratory assistance in newborns of gestational age (GA) ≥ 33 weeks presenting respiratory distress. Multicenter, prospective observational study in third-level neonatal intensive care units. Infants with GA ≥ 33 + 0 weeks with respiratory distress within 3 h of life. Three LUS for each patient were collected: within 3 h of life (T0), at 4-6 h of life (T1), and at the resolution of symptoms (T2). The primary aim was to assess the validity of the early LUS score in predicting the need for continuous positive airway pressure(CPAP). We also evaluated the validity of the score in predicting the need for surfactant, the scores' trend in our population, and any correlation with the duration of ventilation and oxygen therapy. Sixty-two patients were enrolled in the study. The mean GA was 36 weeks. The receiver operating characteristic analysis for the LUS T0 and T1 yielded area under the curves of 0.91 and 0.82 in predicting the need for CPAP, respectively. LUS score cut off of 6 (sensitivity 84.8%, specificity 86.2%) and 5 (sensitivity 66.7%, specificity 100%) were calculated at T0 and T1, respectively. We found significant correlations between LUS score and respiratory assistance, surfactant administration, and SpO2 /FiO2 ratio. An early LUS score is a good noninvasive predictor of the need for respiratory assistance with CPAP and surfactant administration in newborns with GA ≥ 33 weeks.

Impact of nocturnal hypoxemia on the recurrence of atrial tachyarrhythmia after catheter ablation of atrial fibrillation.

Factors causing atrial tachyarrhythmia recurrence after catheter ablation (CA) of atrial fibrillation (AF) remain undetermined. This study aimed to investigate the effect of nocturnal hypoxemia on the recurrence of atrial tachyarrhythmia after CA of AF. Among 594 patients with AF who underwent an ambulatory sleep study at the National Cerebral and Cardiovascular Center, Suita, Osaka, Japan (2014-2019), 365 underwent CA of AF; 290 patients who underwent CA were followed up for > 3months. Multivariate Cox regression analysis was used to calculate hazard ratios (HRs) using clinical variables, to identify the independent predictors of atrial tachyarrhythmia recurrence after the final CA. Atrial tachyarrhythmia recurred in 45 of 290 (15.5%) patients during the median follow-up period of 479days (interquartile range 225-1002). On the performing multivariate analysis of the data of patients who did not receive continuous positive airway pressure (CPAP), severe nocturnal hypoxemia [defined as the percentage of sleep time spent with SaO2 of < 90% (T90) over 20%] [HR 8.53, 95% confidence interval (CI) 1.872-38.814; P < 0.01] and an 1mL/m2 increase in the left atrial volume index (HR 1.02, 95% CI 1.004-1.044; P = 0.02) were found to be independently associated with the recurrence of atrial tachyarrhythmia. In addition, the rates of freedom from atrial tachyarrhythmia after the final AF ablation with CPAP were significantly lower in the group with more severe nocturnal hypoxemia (Log-rank P = 0.03). In conclusion, it is necessary to consider both, AHI and nocturnal hypoxia while performing an ambulatory sleep apnea study. CA may be less effective in patients with more severe nocturnal hypoxia, despite the administration of CPAP.

CPAP vs therapy in infants being transported due to acute respiratory failure

ObjectiveThe aims of our study were to assess the effectiveness and safety of continuous positive airway pressure (CPAP) during the transport of infants with acute respiratory failure (ARF) and to compare the disease course and clinical outcomes of CPAP vs oxygen therapy in the PICU setting. Materials and methodsWe conducted a retrospective observational and analytical study by reviewing the health records of infants with ARF aged 0–12 months that required interhospital transfer to the PICU. ResultsWe included 110 patients: 71 transported with CPAP and 39 with oxygen therapy. The main cause of ARF was acute bronchiolitis (81.8%). The median level of CPAP was 7 cmH2O (interquartile range, 6–7). Controlling for the values prior to transfer in the specific multivariate models, we found that CPAP achieved a significant decrease in the Wood-Downes score (β = –1.08; 95% CI = –1.76 to –0.40; P = .002) and the heart rate ( β = –19.64; 95% CI = –28.46 to –10.81; P < .001). No patients required endotracheal intubation during transport. During the PICU stay, the intubation rate was similar in the CPAP group (7%) and the oxygen therapy group (5.1%) (P = .689). The proportion of patients that required bilevel positive airway pressure within 6 h of admission to the PICU was higher in the oxygen therapy group: 100% (11/11) vs 69.2% (18/26), P = .04. ConclusionsEarly administration of CPAP to infants with ARF was a safe respiratory support intervention during interhospital transport. During patient transport, the use of CPAP achieved greater decreases in the Wood-Downes score and heart rate compared to oxygen therapy.

Qualitative Assessment of the Effect of Continuous Positive Airway Pressure on the Nasal Cavity.

For patients with obstructive sleep apnea (OSA), there is a lack of knowledge regarding the impact of continuous positive airway pressure (CPAP) on the nasal cavity. There is a significant need for evidence-based recommendations regarding the appropriate use of CPAP following endoscopic sinus and skull base surgery. The goal of this study is to translate a previously developed cadaveric model for evaluating CPAP pressures in the sinonasal cavity by showing safety in vivo and quantifying the effect of positive pressurized air flow on the nasal cavity of healthy individuals where physiologic effects are at play. A previously validated cadaveric model using intracranial sensor catheters has proved to be a reliable technique for measuring sinonasal pressures. These sensors were placed in the nasal cavity of 18 healthy individuals. Pressure within the nose was recorded at increasing levels of CPAP. Overall, nasal cavity pressure was on average 85% of delivered CPAP. The amount of pressure delivered to the nasal cavity increased as the CPAP increased. The percentage of CPAP delivered was 77% for 5 cmH2O and increased to 89% at 20 cmH2O. There was a significant difference in mean intranasal pressures between all the levels of CPAP except 5 cmH2O and 8 cmH2O (P < .001). On average, only 85% of the pressure delivered by CPAP is transmitted to the nasal cavity. Higher CPAP pressures delivered a greater percentage of pressurized air to the nasal cavity floor. Our results are comparable to the cadaver model, which demonstrated similar pressure delivery even in the absence of anatomic factors such as lung compliance, nasal secretions, and edema. This study demonstrates the safety of using sensors in the human nasal cavity. This technology can also be utilized to evaluate the resiliency of various repair techniques for endoscopic skull base surgery with CPAP administration.

Case 3: A Term Newborn with Intrauterine Growth Restriction and Severe Fetal Brain Anomalies

A 29-year-old gravida 4, para 3 woman is seen by the maternal-fetal medicine team because of abnormal ultrasonographic findings at 34 weeks of gestation. The fetus has severe intrauterine growth restriction (IUGR) (<1st percentile) and multiple organ abnormalities, including microcephaly, small forebrain, scalloped parietal bones, bilateral ventriculomegaly, dilated third ventricle, splayed thalami, irregular falx, scattered intracranial calcifications, and a small, flattened forehead. Fetal echocardiography shows levorotation of the cardiac axis, tortuous ductus arteriosus, and tricuspid valve thickening. Her prenatal history is notable for travel to the Dominican Republic until 12 weeks of gestation. She denies any fever, insect bites, rash, conjunctivitis, or arthralgia. Findings on other prenatal laboratory screening are reassuring. After the induction of labor for IUGR, a male infant is delivered at 37 2/7 weeks of gestation via normal spontaneous vaginal delivery. Brief positive pressure ventilation is given in the delivery room for an initial low heart rate. The heart rate quickly recovers, but respiratory distress develops, requiring continuous positive airway pressure (CPAP). The infant is transferred to the NICU with the administration of CPAP. Upon admission, physical examination shows a boy with a birthweight of 2,140 g (2.8th percentile), length of 40.5 cm (<1st percentile), and head circumference of 29 cm (<1st percentile). Pertinent findings include microcephaly and global hypertonia, along with contractures of the upper and lower extremities (Fig 1). Figure 1. Contractures of upper and lower extremities. …

Effect of continuous positive airway pressure administration during lung stereotactic ablative radiotherapy: acomparative planning study.

By increasing lung volume and decreasing respiration-induced tumour motion amplitude, administration of continuous positive airway pressure (CPAP) during stereotactic ablative radiotherapy (SABR) could allow for better sparing of the lungs and heart. In this study, we evaluated the effect of CPAP on lung volume, tumour motion amplitude and baseline shift, as well as the dosimetric impact of the strategy. Twenty patients with lung tumours referred for SABR underwent 4D-computed tomography (CT) scans with and without CPAP (CPAP/noCPAP) at two timepoints (T0/T1). First, CPAP and noCPAP scans were compared for lung volume, tumour motion amplitude, and baseline shift. Next, CPAP and noCPAP treatment plans were computed and compared for lung dose parameters (mean lung dose (MLD), lung volume receiving 20 Gy (V20Gy), 13 Gy (V13Gy), and 5 Gy (V5Gy)) and mean heart dose (MHD). On average, CPAP increased lung volume by 8.0% (p < 0.001) and 6.3% (p < 0.001) at T0 and T1, respectively, but did not change tumour motion amplitude or baseline shift. As a result, CPAP administration led to an absolute decrease in MLD, lung V20Gy, V13Gy and V5Gy of 0.1 Gy (p = 0.1), 0.4% (p = 0.03), 0.5% (p = 0.04) and 0.5% (p = 0.2), respectively, while having no significant influence on MHD. In patients referred for SABR for lung tumours, CPAP increased lung volume without modifying tumour motion or baseline shift. As aresult, CPAP allowed for aslight decrease in radiation dose to the lungs, which is unlikely to be clinically significant.

Comparison of three continuous positive airway pressure (CPAP) interfaces in healthy Beagle dogs during medetomidine–propofol constant rate infusions

ObjectiveTo compare the efficacy of three continuous positive airway pressure (CPAP) interfaces in dogs on gas exchange, lung volumes, amount of leak during CPAP and rebreathing in case of equipment failure or disconnection. Study designRandomized, prospective, crossover, experimental trial. AnimalsTen purpose-bred Beagle dogs. MethodsDogs were in dorsal recumbency during medetomidine–propofol constant rate infusions, breathing room air. Three interfaces were tested in each dog in a consecutive random order: custom-made mask (M), conical face mask (FM) and helmet (H). End-expiratory lung impedance (EELI) measured by electrical impedance tomography was assessed with no interface (baseline), with the interface only (No-CPAP for 3 minutes) and at 15 minutes of 7 cmH2O CPAP (CPAP-delivery). PaO2 was assessed at No-CPAP and CPAP-delivery, partial pressure of inspired carbon dioxide (PICO2; rebreathing assessment) at No-CPAP and the interface leak (ΔPleak) at CPAP-delivery. Mixed-effects linear regression models were used for statistical analysis (p<0.05). ResultsDuring CPAP-delivery, all interfaces increased EELI by 7% (p<0.001). Higher ΔPleak was observed with M and H (9 cmH2O) in comparison with FM (1 cmH2O) (p<0.001). At No-CPAP, less rebreathing occurred with M (0.5 kPa, 4 mmHg) than with FM (1.8 kPa, 14 mmHg) and with H (1.4 kPa, 11 mmHg), but also lower PaO2 was measured with M (9.3 kPa, 70 mmHg) than with H (11.9 kPa, 90 mmHg) and FM (10.8 kPa, 81 mmHg). Conclusions and clinical relevanceAll three interfaces can be used to provide adequate CPAP in dogs. The leak during CPAP-delivery and the risk of rebreathing and hypoxaemia, when CPAP is not maintained, can be significant. Therefore, animals should always be supervised during administration of CPAP with any of the three interfaces. The performance of the custom-made M was not superior to the other interfaces.

Impact of Prophylactic Continuous Positive Airway Pressure on Transient Tachypnea of the Newborn and Neonatal Intensive Care Admission in Newborns Delivered by Elective Cesarean Section.

This study aims to evaluate the effect of the prophylactic continuous positive airway pressure (CPAP) administration in the delivery room to newborns who were delivered by elective cesarean section (CS). Inborn infants with gestational age between 34(0/7) to 38(6/7) and born by elective CS were prospectively randomized to receive either prophylactic CPAP for 20 minutes via face mask or standardized care without CPAP in the delivery room. Primary outcomes were the incidence of transient tachypnea of the newborn (TTN) and neonatal intensive care unit (NICU) admission due to respiratory distress. A total of 259 infants with a mean gestational age of 37.7 ± 0.8 weeks and birth weight of 3,244 ± 477 g were included. A total of 134 infants received prophylactic CPAP and 125 received control standard care. The rate of NICU admission was significantly lower in prophylactic CPAP group (p = 0.045). Although the rate of TTN was lower in the prophylactic CPAP group, the difference was not statistically significant (p = 0.059). The rate of NICU admission due to respiratory distress was significantly higher in late-preterm cohort than early-term cohort (p < 0.0001). Prophylactic CPAP administration decreases the rate of NICU admission without any side effect in late-preterm and early-term infants delivered by elective CS.

PP.37.07

Objective: Obstructive sleep apnea (OSA), particularly when moderate to severe, has been shown to be associated with impaired left ventricular (LV) diastolic function. Several studies suggested that a period of a long-term apnea reversal with continuous positive airway pressure (CPAP) may result in amelioration of diastolic cardiac dysfunction markers. We tested the hypothesis whether acute CPAP administration (7 nights) influences diastolic heart properties in newly-diagnosed obstructive sleep apnea patients with hypertension. Design and method: We enrolled 50 hypertensive subjects with newly-diagnosed moderate-to-severe OSA established with in-clinic polygraphic recordings (Embletta X30). All patients were offered CPAP treatment for one week, and underwent echocardiographic recordings (Vivid 7 Pro) - before and after one week of effective (AHI < 5, usage > 4 hours/night) CPAP. Results: 9 patients refused CPAP and 1 was diagnosed with mitral heart defect thus were excluded from analyses. Patients were 57 ± 7 years old, with BMI = 33.2 ± 7.0 kg/m2, AHI = 29.9 ± 31.2, and SpO2 = 93.3 ± 2.8. One week of CPAP therapy was associated with an office blood pressure (BP) decrease by 8/6 mm Hg for systolic and diastolic BP, respectively. There was no correlation between the magnitude of blood pressure fall and any of the indices of sleep disordered breathing (P = NS for all comparisons). CPAP therapy improved only few diastolic function markers eg. E-wave from 0.74 ± 0.21 to 0.80 ± 0.26; P = 0.03; and Ar (atrial pulmonary vein reversal flow velocity) from 0,32 ± 0,06 to 0,30 ± 0,06; P = 0,06; before and after CPAP therapy. However, there was an evident correlation between baseline PSG-derived mean oximetry (SpO2) and the deltas of the echocardiographic markers denoting changes in diastolic performance in response to CPAP (Table).E-Early diastolic mitral flow velocity; A-Late diastolic mitral flow velocity; E’- early diastolic mitral annulus velocity; A’-late diastolic mitral annulus velocity. Conclusions: Short-term effective CPAP improves diastolic function in OSA hypertensive patients. These beneficial effects appear to be independent of office blood pressure changes and may be directly linked to sleep apnea severity.

Effects of CPAP on clinical variables and autonomic modulation in children during an asthma attack

Continuous positive airway pressure (CPAP) causes changes in alveolar and intrathoracic pressure and the activation of pulmonary stretch receptors affects the balance of the autonomic nervous system. The acute effects of CPAP on autonomic modulation have been demonstrated in different diseases, but no studies have been carried out addressing CPAP in patients with asthma. The hypothesis tested in the present study is that CPAP can produce an autonomic effect beyond a mechanical effect of bronchial dilatation in children with asthma. The results demonstrated improvements in clinical variables and an increase in vagal tone with the administration of CPAP during an asthma attack, as demonstrated by a diminished respiratory rate and a reduction in signs of respiratory distress. Regarding autonomic modulation, an increase in parasympathetic variables was found, indicating non-cholinergic activation stemming from the persistent increase in peak flow.

Neurodevelopmental Outcomes in the Early CPAP and Pulse Oximetry Trial

BackgroundPrevious results from our trial of early treatment with continuous positive airway pressure (CPAP) versus early surfactant treatment in infants showed no significant difference in the outcome of death or bronchopulmonary dysplasia. A lower (vs. higher) target range of oxygen saturation was associated with a lower rate of severe retinopathy but higher mortality. We now report longer-term results from our prespecified hypotheses.MethodsUsing a 2-by-2 factorial design, we randomly assigned infants born between 24 weeks 0 days and 27 weeks 6 days of gestation to early CPAP with a limited ventilation strategy or early surfactant administration and to lower or higher target ranges of oxygen saturation (85 to 89% or 91 to 95%). The primary composite outcome for the longer-term analysis was death before assessment at 18 to 22 months or neurodevelopmental impairment at 18 to 22 months of corrected age.ResultsThe primary outcome was determined for 1234 of 1316 enrolled infants (93.8%); 990 of the 1058 surviving infants (93.6%) were evaluated at 18 to 22 months of corrected age. Death or neurodevelopmental impairment occurred in 27.9% of the infants in the CPAP group (173 of 621 infants), versus 29.9% of those in the surfactant group (183 of 613) (relative risk, 0.93; 95% confidence interval [CI], 0.78 to 1.10; P=0.38), and in 30.2% of the infants in the lower-oxygen-saturation group (185 of 612), versus 27.5% of those in the higher-oxygen-saturation group (171 of 622) (relative risk, 1.12; 95% CI, 0.94 to 1.32; P=0.21). Mortality was increased with the lower-oxygen-saturation target (22.1%, vs. 18.2% with the higher-oxygen-saturation target; relative risk, 1.25; 95% CI, 1.00 to 1.55; P=0.046).ConclusionsWe found no significant differences in the composite outcome of death or neurodevelopmental impairment among extremely premature infants randomly assigned to early CPAP or early surfactant administration and to a lower or higher target range of oxygen saturation. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Heart, Lung, and Blood Institute; SUPPORT ClinicalTrials.gov number, NCT00233324.)

Outcome of extremely low gestational age newborns after introduction of a revised protocol to assist preterm infants in their transition to extrauterine life

To evaluate the outcome of a cohort of extremely low gestational age newborn infants (ELGAN) below 26-week gestation who were treated following a revised, gentle delivery room protocol to assist them in the transition and adaptation to extrauterine life. A cohort of infants with a gestational age (GA) below 26 weeks (study group; n = 164) was treated according to a revised delivery room protocol. The protocol included an optimized prenatal management, strict use of continuous positive airway pressure (CPAP), avoiding mechanical ventilation and early administration of surfactant without intubation. The parameters management of respiratory distress syndrome, survival, neonatal morbidity and neurodevelopmental outcome were compared with a historical control group (n = 44). Seventy-four per cent of the study group infants were initially treated with CPAP and surfactant administration without intubation. In comparison with the control group, significantly less children were intubated in the delivery room (24% vs. 41%) and needed mechanical ventilation (51% vs. 72%; both p < 0.05). Furthermore, compared with the historical control overall mortality (20% vs. 39%), rate of bronchopulmonary dysplasia (18% vs. 37%) and IVH > II° (10% vs. 33%) in survivors were significantly lower during the observational period (all p < 0.05). Neurodevelopmental outcome was normal in 70% of examined study group infants. A revised delivery room management protocol was applied safely to infants with a GA below 26 completed weeks with improved rates of survival and morbidity.

Use of Bioimpedance to Assess Changes in Hemodynamics During Acute Administration of CPAP.

BackgroundAttempts to investigate the mechanisms by which continuous positive airway pressure (CPAP) therapy improves heart function in patients with obstructive sleep apnea (OSA) have been limited by the lack of non-invasive methods to assess cardiac performance. We used transthoracic electrical bioimpedance (TEB) to assess acute hemodynamic changes including heart rate (HR), stroke volume (SV), cardiac output (CO) and cardiac index (CI) during PAP titration in (1) post-operative cardiac surgery patients, (2) patients with severe OSA, and (3) normal healthy volunteers.MethodsPost-operative cardiac surgery patients were studied via TEB and pulmonary artery catheter (PAC) during acute titration of positive end-expiratory pressure (PEEP) while mechanically ventilated. Patients with severe OSA were studied non-invasively by TEB during acute CPAP titration in supine stage 2 sleep, and normal subjects while awake and recumbent.ResultsIn post-operative cardiac surgery patients (n = 3), increasing PEEP to 18 cmH2O significantly reduced SV and CI relative to baseline. There was no difference between TEB and PAC in terms of ability to assess variations in hemodynamic parameters. In patients with severe OSA (n = 3), CPAP titration to optimal pressure to alleviate obstructive apneas reduced HR, SV, CO and CI significantly compared to without CPAP. In three healthy subjects, maximal tolerated CPAP reduced SV and CO significantly compared to baseline.ConclusionsAcute administration of CPAP causes a decrease in CO and CI, apparently a consequence of a reduction in SV. TEB appears to be an accurate and reproducible non-invasive method of detecting changes in hemodynamics.

Effects of Nasal Continuous Positive Airway Pressure and Cannula Use in the Neonatal Intensive Care Unit Setting

To investigate the effects of nasal continuous positive airway pressure (CPAP) and cannula use in the neonatal intensive care unit. Cross-sectional study. Tertiary care children's hospital. One hundred patients (200 nasal cavities), younger than 1 year, who received at least 7 days of nasal CPAP (n = 91) or cannula supplementation (n = 9) in the neonatal intensive care unit. External nasal examination and anterior nasal endoscopy with photographic documentation. The incidence and characteristics of internal and external nasal findings of patients with nasal CPAP or cannula use. Nasal complications were seen in 12 of the 91 patients (13.2%) with at least 7 days of nasal CPAP exposure, while no complications were seen in the 9 patients with nasal cannula use alone. The external nasal finding of columellar necrosis, seen in 5 patients (5.5%), occurred as early as 10 days after nasal CPAP use. Incidence of intranasal findings attributed to CPAP use, in the 182 nostrils examined, included ulceration in 6 nasal cavities (3.3%), granulation in 3 nasal cavities (1.6%), and vestibular stenosis in 4 nasal cavities (2.2%). Intranasal complications were seen as early as 8 to 9 days after nasal CPAP administration. Nasal complications from CPAP were associated with lower Apgar scores at 1 (P = .02) and 5 (P = .06) minutes. External or internal complications of nasal CPAP can be relatively frequent (13.2%) and can occur early, and patients with lower Apgar scores may be at higher risk. Close surveillance for potential complications should be considered during nasal CPAP use.

Complex sleep apnea and obesity hypoventilation syndrome. Opposite ends of the spectrum of obstructive sleep apnea?

In most cases, the application of continuous positive airway pressure (CPAP) during sleep in patients affected by obstructive sleep apnea (OSA) eliminates upper airway obstruction and makes breathing stable and regular. However, some OSA patients develop periodic breathing and central apneas during CPAP administration, a finding that has been labelled as "complex sleep apnea" (complex SA). Such breathing disorder may occur only acutely after CPAP treatment initiation or sometimes persist with chronic CPAP treatment. We hypothesize that complex SA may be the consequence of mechanisms analogous to those leading to obesity hypoventilation syndrome (OHS), but operating in an opposite direction. Periodic breathing is one of the factors predisposing to OSA and is an essential factor for the recurrence of central apneas in normo or hypocapnic patients. A high ventilatory responsiveness to chemical stimuli enhances breathing periodicity. In subjects with periodic central apneas chemoresponsiveness is high, while in subjects with OSA it spans throughout a wide range, and is correlated to diurnal blood gas levels. In fact, sleep respiratory disorders may be responsible for either an augmentation in ventilatory responses to chemical stimuli consequent to chronic exposure to intermittent hypoxia, or for a decrease in ventilatory responses when prolonged exposure to hypercapnia is experienced. Among OSA subjects, those with OHS show very depressed hypercapnic responses. After chronic OSA treatment, ventilatory responses to chemical stimuli may either decrease, in previously hyperresponsive subjects, or increase, in previously hyporesponsive subjects. Most patients with OHS decrease daytime PCO(2) levels and increase their ventilatory responses after chronic CPAP treatment. Complex SA could appear in those OSA subjects in whom chronic exposure to nocturnal respiratory disorders leads to the highest responsiveness to chemical stimuli, and could disappear after blunting of ventilatory responses following chronic CPAP treatment. Complex SA may be one extreme of evolutionary spectrum of OSA, the opposite end being represented by OHS.

Postoperative Monitoring of Esophageal Pressure in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome Who Have Undergone Tonsillectomy with Uvulopalatopharyngoplasty

To realize better postoperative management in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), we elucidated the need for the postoperative monitoring of esophageal pressure (Pes). A prospective randomized controlled study was performed. Adult patients with OSAHS were divided into 2 groups: those administered autoadjusted continuous positive airway pressure (CPAP) before, on, and after the first postoperative night (CPAP group) and those not administered CPAP before or after the surgery (non-CPAP group). Tonsillectomy with uvulopalatopharyngoplasty (UPPP) under general anesthesia was performed on all of the patients. On the first postoperative night, continuous overnight monitoring of Pes and oxygen saturation level was carried out simultaneously with oxygen supplementation in both groups in the patient's room in the general ward. The CPAP group showed a significantly improved mean inspiratory maximal end-apneic Pes swing on the first postoperative night as compared with the non-CPAP group, although there was no significant difference in oxygen desaturation index on the first postoperative night between the 2 groups. Continuous Pes monitoring and CPAP administration were beneficial in the detection and minimization of respiratory disturbances in patients with OSAHS who underwent tonsillectomy with UPPP under general anesthesia.

Acute and chronic effects of continuous positive airway pressure therapy on left ventricular systolic and diastolic function in patients with obstructive sleep apnea and congestive heart failure

Obstructive sleep apnea (OSA) may contribute to the pathogenesis of congestive heart failure (CHF). Nocturnal continuous positive airway pressure (CPAP) therapy can alleviate OSA and may have a role in the treatment of CHF patients. To investigate the acute and chronic effects of CPAP therapy on left ventricular systolic function, diastolic function and filling pressures in CHF patients with OSA. Twelve patients with stable CHF (New York Heart Association II or III, radionuclide ejection fraction lower than 40%) underwent overnight polysomnography to detect OSA. In patients with OSA (n=7), echocardiography was performed at baseline (awake, before and during acute CPAP administration) and after 6.9+/-3.3 weeks of nocturnal CPAP therapy. Patients without OSA (n=5) did not receive CPAP therapy, but underwent a baseline and follow-up echocardiogram. In CHF patients with OSA, acute CPAP administration resulted in a decrease in stroke volume (44+/-15 mL versus 50+/-14 mL, P=0.002) and left ventricular ejection fraction ([LVEF] 34.8+/-5.0% versus 38.4+/-3.3%, P=0.006) compared with baseline, but no change in diastolic function or filling pressures (peak early diastolic mitral annular velocity [Ea]: 6.0+/-1.6 cm/s versus 6.3+/-1.6 cm/s, P not significant; peak early filling velocity to peak late filling velocity [E/A] ratio: 1.05+/-0.74 versus 1.00+/-0.67, P not significant; E/Ea ratio: 10.9+/-4.1 versus 11.3+/-4.1, P not significant). In contrast, chronic CPAP therapy resulted in a trend to an increase in stroke volume (59+/-19 mL versus 50+/-14 mL, P=0.07) and a significant increase in LVEF (43.4+/-4.8% versus 38.4+/-3.3%, P=0.01) compared with baseline, but no change in diastolic function or filling pressures (Ea: 6.2+/-1.2 cm/s versus 6.3+/-1.6 cm/s, P not significant; E/A ratio: 1.13+/-0.61 versus 1.00+/-0.67, P not significant; E/Ea ratio: 12.1+/-2.7 versus 11.3+/-4.1, P not significant). There was no change in left ventricular systolic function, diastolic function or filling pressures at follow-up in CHF patients without OSA. Acute CPAP administration decreased stroke volume and LVEF in stable CHF patients with OSA. In contrast, chronic CPAP therapy for seven weeks improved left ventricular systolic function, but did not affect diastolic function or filling pressures. The potential clinical implications of the discrepant effects of CPAP therapy on left ventricular systolic and diastolic function in CHF patients with OSA warrant further study.