Nasal versus oronasal continuous positive airway pressure masks for obstructive sleep apnea: a pilot investigation of pressure requirement, residual disease, and leak

Purpose

This single-blinded, randomized, controlled pilot study aimed to investigate whether there is a difference between nasal and oronasal masks in therapeutic continuous positive airway pressure (CPAP) requirement, residual disease, or leak when treating obstructive sleep apnea (OSA) and if differences were related to measures of upper airway size.

Methods

Patients with severe OSA currently using CPAP at ??4?h/night with a nasal mask were examined (including Mallampati scale, incisal relationship, and mandibular protrusion) and then randomized to receive auto-positive airway pressure (PAP) or fixed CPAP at a manually titrated pressure for 1?week each at home, with immediate crossover. Within each week, a nasal mask and two oronasal masks were to be used for two or three nights each in random order. Data were downloaded from the device.

Results

Twelve patients completed the trial (mean ± SD AHI 59.8?±?28.6 events/h; CPAP 11.1?±?3.2?cmH₂O; BMI 37.7?±?5.0?kg/m²). During auto-PAP, the median 95th percentile pressure delivered with all masks was within 0.5?cmH₂O (p?>?0.05). During CPAP, median residual AHI was 0.61 (IQR?=?1.18) for the nasal mask, 1.70 (IQR?=?4.04) for oronasal mask 1, and 2.48 (IQR?=?3.74) for oronasal mask 2 (p?=?0.03). The 95th percentile leak was lowest with the nasal mask during both CPAP and auto-PAP (both p?Conclusions In obese OSA patients changing from a nasal to oronasal mask increased leak and residual AHI but did not affect the therapeutic pressure requirement. The findings of the current study highlight mask leak as the major difficulty in the use of oronasal masks.     

Oronasal masks require higher levels of positive airway pressure than nasal masks to treat obstructive sleep apnea

Purpose

The purpose of this study was to compare the therapeutic pressure determined by an automated CPAP device (AutoCPAP) during the titration period, between nasal and oronasal mask and the residual apnea-hypopnea index (AHI) on a subsequent poligraphy performed with the established therapeutic CPAP.

Methods

As a retrospective study, 109 subjects with moderate and severe obstructive sleep apnea-hypopnea (apnea-hypopnea index?≥?15 events/h) were studied. CPAP titration was performed using an auto-titrating device.

Results

There was significant difference in the mean pressure delivered with autoCPAP between the group of patients using the nasal mask (mean 10.0 cmH₂O?±?2.0 SD) and the group which used the oronasal mask (mean 11.2 cmH₂O?±?2.1) (p?p?r?=?0.245, p 0.008).

Conclusions

Therapeutic CPAP level for OSAH is higher when administered via oronasal mask, leaving more residual events. These findings suggest that nasal mask should be the first choice for OSAH treatment.     

Comparison of the upper airway dynamics of oronasal and nasal masks with positive airway pressure treatment using cine magnetic resonance imaging

Purpose

It is known that oronasal masks are not as effective at opening the upper airway compared to nasal only continuous positive airway pressure (CPAP) masks in patients with sleep-disordered breathing. However, the physiological mechanism for this difference in efficacy is not known; although, it has been hypothesized to involve the retroglossal and/or retropalatal region of the upper airway. The objective of this study was to investigate differences in retroglossal and retropalatal anterior-posterior space with the use of oronasal vs. nasal CPAP masks using real-time cine magnetic resonance imaging (cMRI).

Methods

Ten subjects (eight men, two women) with obstructive sleep apnea (OSA) were given cMRI with both nasal and oronasal CPAP masks. Each subject was imaged with each interface at pressures of 5, 10, and 15 cm of H₂O, while in the supine position along the sagittal plane.

Results

The oronasal mask produced significantly less airway opening in the retropalatal region of the upper airway compared to the nasal mask interface. During exhalation, mask style had a significant effect on anterior-posterior distance p?=?0.016. No differences were found in the retroglossal region between mask styles.

Conclusions

Our study confirmed previous findings showing differences in treatment efficacy between oronasal and nasal mask styles. We have shown anatomic evidence that the nasal mask is more effective in opening the upper airway compared to the oronasal mask in the retropalatal region.

     

Acute Effects of Continuous Positive Air way Pressure on Pulse Pressure in Chronic Heart Failure

Background

Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP.

Objective

The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF.

Methods

Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60 ± 11 years; BMI 29 ± 5 kg/cm², NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH₂O, whereas placebo was fixed at 0-1 cmH₂O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode.

Results

CPAP decreased resting heart rate (Pre: 72 ± 9; vs. Post 5 min: 67 ± 10 bpm; p < 0.01) and MAP (CPAP: 87 ± 11; vs. control 96 ± 11 mmHg; p < 0.05 post 5 min). CPAP decreased PP (CPAP: 47 ± 20 pre to 38 ± 19 mmHg post; vs. control: 42 ± 12 mmHg, pre to 41 ± 18 post p < 0.05 post 5 min).

Conclusion

NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome.     

Patients’ preference of established and emerging treatment options for obstructive sleep apnoea

Background

Obstructive sleep apnoea (OSA) is the most common form of sleep-disordered breathing. The standard treatment, continuous positive airway pressure (CPAP), has limited long-term compliance. Alternative treatment options are required and new methods, including hypoglossal nerve stimulation (HNS) and continuous transcutaneous electrical stimulation (CTES), are currently emerging. We report on patients’ preference for different treatments of OSA.

Methods

We recorded patients’ age, gender, body mass index (BMI), Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire with 10 questions (FOSQ10), severity of OSA, and current treatment. We showed pictures of existing [CPAP, mandibular advancement device (MAD)] and emerging treatments (HNS and CTES). We then asked (I) whether participants were interested in further information about HNS/CTES; (II) if they would be willing to try HNS/CTES; and (III) if they were to choose only one of the four listed treatments, which one would they prefer to use every night.

Results

One hundred sixty-two patients completed the survey {81 males, mean age 52 [12] years, BMI 34 [7] kg/m², ESS 10.2 (6.0) points, FOSQ10 28.5 (8.1) points}. The majority of the respondents (89.5%) had been diagnosed with OSA. A total of 91.3% of the respondents were interested in more information and were willing to try HNS/CTES. Most respondents preferred the potential use of CTES (56.7%), while 21.7% chose HNS, 17.8% CPAP, and 3.8% the MAD. There were no differences in the characteristics of the patients who preferred CTES compared to those who preferred other treatments, but a regression analysis revealed that a low ESS score was an independent predictor of patients choosing CTES (P<0.05).

Conclusions

More than 9 out of 10 of the respondents were interested in trying emerging technologies to treat OSA, most preferring CTES. Less sleepy patients were more likely to choose less invasive treatments. These findings will likely impact on future research and development of therapies for sleep-disordered breathing.     

Nocturnal pulse rate and symptomatic response in patients with obstructive sleep apnoea treated with continuous positive airway pressure for one year

Background

Obstructive sleep apnoea (OSA) is the most common form of sleep-disordered breathing and a known risk factor for cardiovascular disease. We hypothesised that in patients with OSA the characteristics of nocturnal pulse rate (PR) are associated with changes in blood pressure and daytime sleepiness, following commencement of continuous positive airway pressure (CPAP) therapy.

Methods

Pulse oximetry data, demographics, daytime sleepiness and blood pressure were recorded at baseline and at one year follow up. Patients with OSA were grouped according to positive and negative changes in the PR (ΔPR) response during the first night of pulse oximetry before commencement of CPAP.

Results

A total of 115 patients (58 with OSA and 57 matched subjects without OSA) were identified and included in the analysis. The scale of improvement in daytime sleepiness could be predicted by a negative or positive ΔPR, as recorded in the initial screening pulse oximetry [ΔESS –5.8 (5.1) vs. –0.8 (7.2) points, P<0.05]. A negative correlation was observed between mean nocturnal PR and changes in systolic blood pressure (SBP) after one year of CPAP treatment (r=–0.42, P<0.05).

Conclusions

Mean nocturnal PR prior to CPAP initiation was associated with changes in SBP at one year follow up. A descending nocturnal PR in patients with OSA, prior to CPAP initiation, might help to identify a symptomatic response from long term CPAP treatment.     

Screening for sleep-disordered breathing in a bariatric population

Background

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing frequently associated with obesity. Obese subjects undergoing elective surgical procedures with general anesthesia are potentially at risk if this condition is not identified. Our aim was to assess the prevalence of bariatric patients with undiagnosed OSA following pre-operative assessment and who could benefit from peri-procedural respiratory management.

Methods

Patients who were referred for prospective bariatric surgery were screened using the STOP-BANG questionnaire. If patients scored >4 points they underwent a home-based nocturnal pulse oximetry. Severity of OSA was defined by the 4% oxygen desaturation index (ODI) combined with a physician’s review. Data were compared using unpaired two-tailed t-test and Chi-square test. Linear regression models were used to assess associations between clinical parameters.

Results

Sleep-disordered breathing of any degree was evident in 103 of 141 patients (73%). Thirteen (9%) patients had severe, 19 (13%) moderate, and 34 (24%) mild OSA, 38 (27%) patients had no OSA. 34 (24%) patients were initiated on continuous positive airway pressure (CPAP) prior to the surgical procedure, 15 (11%) were admitted for further respiratory assessment and two of them were given CPAP following inpatient sleep study. Thirteen (9%) patients were advised to use a mandibular advancement device for mild but symptomatic OSA. Out of all patients, 76 (54%) were advised that no treatment was required.

Conclusions

OSA is highly prevalent in a cohort of bariatric surgery patients screened with STOP-BANG questionnaires. Almost 3/4 of this cohort have at least some degree of sleep-disordered breathing, and approximately half of them require a plan for the respiratory management perioperatively.     

Effects of changes in lung volume on oscillatory flow rate during high-frequency chest wall oscillation

BACKGROUND:

The effectiveness of high-frequency chest wall oscillation (HFCWO) in mucolysis and mucous clearance is thought to be dependant on oscillatory flow rate (Fosc). Therefore, increasing Fosc during HFCWO may have a clinical benefit.

OBJECTIVES:

To examine effects of continuous positive airway pressure (CPAP) on Fosc at two oscillation frequencies in healthy subjects and patients with airway obstruction.

METHODS:

Five healthy subjects and six patients with airway obstruction underwent 12 randomized trials of HFCWO (CPAP levels of 0 cm H₂O, 2 cm H₂O, 4 cm H₂O, 6 cm H₂O, 8 cm H₂O and 10 cm H₂O at frequencies of 10 Hz and 15 Hz) within a body plethysmograph, allowing measurements of changes in lung volume. Fosc was measured by reverse plethysmography using a 20 L isothermic chamber near the mouth. At the end of each randomized trial, an inspiratory capacity manoeuvre was used to determine end-expiratory lung volume (EELV).

RESULTS:

EELV increased significantly (P<0.05) with each level of CPAP regardless of oscillation frequency. Fosc also significantly increased with CPAP (P<0.05) and it was correlated with EELV (r=0.7935, P<0.05) in obstructed patients but not in healthy subjects (r=0.125, P=0.343). There were no significant differences in perceived comfort across the levels of CPAP.

CONCLUSIONS:

Significant increases in Fosc with CPAP-induced increases in lung volume were observed, suggesting that CPAP may be useful as a therapeutic adjunct in patients who have obstructive airway disease and who require HFCWO.     

Airway pressure and transpulmonary pressure during high-frequency oscillation for acute respiratory distress syndrome

High-frequency oscillation is a novel form of ventilation increasingly being used to treat refractory hypoxic respiratory failure resulting from acute lung injury or acute respiratory distress syndrome. Although there is no known relationship between airway pressure and transpulmonary pressure during conventional mechanical ventilation, no study has attempted to determine transpulmonary pressure during high-frequency oscillation.

BACKGROUND:

High-frequency oscillation (HFO) is used for the treatment of refractory hypoxic respiratory failure.

OBJECTIVE:

To demonstrate that the mean transpulmonary pressure (P_L) cannot be inferred from mean airway pressure (mPaw).

METHODS:

In seven patients already undergoing HFO for refractory acute respiratory distress syndrome, esophageal pressure (Pes) was measured using an esophageal balloon catheter. Pleural pressure (Ppl) and P_L were calculated from Pes.

MAIN RESULTS:

In the seven patients (mean [± SD] age 59±9 years) treated with HFO at 5±1 Hz and amplitude 75±10 cmH₂O, the mPaw was 27±6 cmH₂O, Ppl was 9±6 cmH₂O and P_L was 18±11 cmH₂O. Successful catheter placement and measurement of Pes occurred in 100% of subjects. There was no correlation between P_L and mPaw. The majority of subjects required hemodynamic support during the use of HFO; the frequency and degree of support during the study period was no different than that before the study.

CONCLUSION:

The present report is the first to describe measuring Pes and calculating Ppl during HFO for acute respiratory distress syndrome. While both current guidelines and recent trials have titrated treatment based on mPaw and oxygenation, there is wide variability in P_L during HFO and P_L cannot be predicted from mPaw.     

Mandibular advancement device and CPAP upon cardiovascular parameters in OSA

Purpose

This study aims to compare the effects of a mandibular advancement device (MAD) with continuous positive airway pressure (CPAP) treatment for obstructive sleep apnea (OSA) on blood pressure (BP), oxidative stress, and heart rate variability (HRV) in a randomized, crossed-over, single-blind, and controlled trial.

Methods

Twenty-nine moderate-to-severe adult OSA patients underwent MAD, CPAP, and placebo oral appliance treatment. Polysomnography, Epworth sleepiness scale, 24-h ambulatory BP monitoring, oxidative stress parameters (malondialdehyde, catalase, superoxide dismutase, vitamins C, E, B₆, B₁₂, folate, homocysteine, uric acid), and HRV were assessed at baseline and after 1 month of each treatment. Diaries were used to evaluate compliance for devices and a pressure–time meter for CPAP.

Results

Both active treatments resulted in decreases in apnea and hypopnea index and Epworth sleepiness scale; CPAP showed a greater effect. Frequency of diastolic BP dipping was higher in the MAD group compared with the CPAP group. A significant drop from baseline levels for catalase activity was observed after MAD. For HRV, there was a significant decrease in total power at night with CPAP and MAD compared with POA, and a decrease in index of sleep autonomic variation with MAD compared with baseline levels. Compliance rates were higher with MAD rather than CPAP.

Conclusions

Even though CPAP proved to be more effective at attenuating OSA, better compliance with MAD favored the reduction of one of the enzymes which participates in oxidative stress and better autonomic modulation during sleep.     

Do obstructive sleep apnea syndrome patients underestimate their daytime symptoms before continuous positive airway pressure treatment?

BACKGROUND:

Daytime somnolence is an important feature of the obstructive sleep apnea (OSA) hypopnea syndrome and is usually subjectively assessed using the Epworth Sleepiness Scale (ESS).

OBJECTIVE:

To compare the scores of the ESS and different domains of the Quebec Sleep Questionnaire (QSQ) assessed before and after the first months of continuous positive airway pressure (CPAP) treatment, as well as retrospectively without treatment.

METHODS:

The ESS score and domain scores of the QSQ were obtained before and after a three-month period of CPAP treatment using a retrospective assessment of the pretreatment scores in 76 untreated OSA patients.

RESULTS:

Fifty-two patients completed the study. The ESS and QSQ scores significantly improved following CPAP therapy. Retrospective evaluation of the ESS score was significantly worse than pre- and post-treatment values (mean [± SD] pretreatment score 11.0±4.8; retrospective pretreatment score 13.5±5.1). Such differences were not observed in any domain of the QSQ, including the domain assessing hypersomnolence.

CONCLUSION:

OSA patients underestimated their sleepiness according to the most widely used instrument to assess hypersomnolence. This finding may not be observed with other methods used to assess OSA-related symptoms such as quality of life questionnaires.     

Oral continuous positive airway pressure for sleep apnea: effectiveness, patient preference, and adherence

BACKGROUND: Nasal continuous positive airway pressure (CPAP) is the most definitive medical therapy for obstructive sleep apnea (OSA). Many patients have difficulty tolerating nasal CPAP due to nasal airway problems, mouth leak, and general discomfort from the mask and headgear. These limitations may be overcome by an oral mask (Oracle; Fisher & Paykel Healthcare; Languna Hills, CA) that does not require headgear. We performed a study to compare the Oracle mask to conventional nasal and oronasal masks in the effectiveness of CPAP delivery and patient satisfaction and adherence. METHODS: Ninety-eight, consecutive CPAP-na?ve patients with OSA diagnosed by overnight polysomnography (apnea-hypopnea index [AHI] > 5) were referred for CPAP therapy. All patients were presented with a variety of CPAP masks, including nasal, oronasal, and Oracle, and reasons for mask choice were documented. After 3 weeks of acclimatization to the mask of their choice, patients had a CPAP titration sleep study to determine their optimal CPAP level. Further follow-up was obtained 2 months and 6 months later with a subjective patient assessment of CPAP use and efficacy, mask comfort, and upper airway dryness. RESULTS: Patients were predominantly male (70%), middle aged (50.6 +/- 11.7 years), and moderately obese (body mass index, 32.5 +/- 9.0) with severe OSA (AHI, 40.6 +/- 25.8/h) [mean +/- SD]. Patients were classified into three groups based on their choice of mask: nasal (66%), Oracle (27%), and oronasal (7%). Baseline characteristics did not differ significantly between groups. Optimal CPAP was not significantly different between mask groups (nasal, 7.7 +/- 2.1 cm H(2)O; Oracle, 8.0 +/- 2.0 cm H(2)O; oronasal, 9.7 +/- 3.2 cm H(2)O; p = 0.267). Subjective ratings of adherence, efficacy, and mask comfort were also similar between groups. However, the Oracle group had more complaints of upper airway dryness and "rain-out." The oronasal group had a disproportionately greater number of dropouts from CPAP therapy than the Oracle group (57% vs 19%, p = 0.046). Nine patients changed from the Oracle mask to a nasal mask during the study, whereas no patients changed from their nasal or oronasal masks. CONCLUSIONS: The Oracle mask is an efficacious interface for long-term CPAP therapy in patients with OSA. The main limitations of the mask are upper airway dryness and rain-out associated with heated humidification, which may be improved by further technical modifications. Oracle may be more acceptable than oronasal masks for patients who cannot rely exclusively on the nasal airway for CPAP therapy.     

A chest drainage system with a real-time pressure monitoring device

Background

Tube thoracostomy is a common procedure. A chest bottle may be used to both collect fluids and monitor the recovery of the chest condition. The presence of the “tidaling phenomenon” in the bottle can be reflective of the extent of patient’s recovery.

Objectives

However, current practice essentially depends on gross observation of the bottle. The device used here is designed for a real-time monitoring of change in pleural pressure to allow clinicians to objectively determine when the lung has recovered, which is crucially important in order to judge when to remove the chest tube.

Methods

The device is made of a pressure sensor with an operating range between −100 to +100 cmH₂O and an amplifying using the “Wheatstone bridge” concept. Recording and analysis was performed with LABview software. The data can be shown in real-time on screen and also be checked retrospectively. The device was connected to the second part of a three-bottle drain system by a three-way connector.

Results

The test animals were two 40-kg pigs. We used a thoracoscopic procedure to create an artificial lung laceration with endoscopic scissors. Active air leaks could result in vigorous tidaling phenomenon up to 20 cmH₂O. In the absence of gross tidaling phenomenon, the pressure changes were around 0.25 cmH₂O.

Conclusions

This real-time pleural pressure monitoring device can help clinicians objectively judge the extent of recovery of the chest condition. It can be used as an effective adjunct with the current chest drain system.     

Determination of new prediction formula for nasal continuous positive airway pressure in Turkish patients with obstructive sleep apnea syndrome

Background

Race/ethnicity may play an important role in determining body size, severity of obstructive sleep apnea syndrome (OSAS), and effective continuous positive airway pressure (CPAP) (Peff). Turkey is composed of different ethnic groups. Therefore, the aims of this study were to determine new prediction formula for CPAP (Ppred) in Turkish OSAS patients, validate performance of this formula, and compare with Caucasian and Asian formulas.

Methods

Peff of 250 newly diagnosed moderate-to-severe OSAS patients were calculated by in-laboratory manual titration. Correlation and multiple linear regression analysis were used to model effects of ten anthropometric and polysomnographic variables such as neck circumference (NC) and oxygen desaturation index (ODI) on Peff. New formula was validated in different 130 OSAS patients and compared with previous formulas.

Results

The final prediction formula was $ {\text{Ppred}} = \left( {0.{148} \times {\text{NC}}} \right) + \left( {0.0{38} \times {\text{ODI}}} \right) $ . When Peff of control group was assessed, it was observed that mean Peff was 8.39?±?2.00?cmH₂O and Ppred was 8.23?±?1.22?cmH₂O. Ppred was within ±3?cmH₂O of Peff in 96.2% patients. Besides, Peff was significantly correlated with new formula, and prediction formulas developed for Caucasian and Asian populations (r?=?0.651, p?<?0.001, r?=?0.648, p?<?0.001, and r?=?0.622, p?<?0.001, respectively).

Conclusions

It is shown that level of CPAP can be successfully predicted from our prediction formula, using NC and ODI and validated in Turkish OSAS patients. New equation correlates with other formulas developed for Caucasian and Asian populations. Our simple formula including ODI, marker of intermittent hypoxia, may be used easily in different populations.     

Analysis of hospital discharge data to characterize obstructive sleep apnea and its management in adult patients hospitalized in Canada: 2006 to 2007

BACKGROUND:

Diagnosed obstructive sleep apnea (OSA) affects 2% to 7% of middle-age persons worldwide and represents a substantial health care burden. The gold standard for treating OSA in adults is continuous positive airway pressure (CPAP) therapy. Compliance with this treatment is especially important in OSA patients experiencing concomitant acute and chronic disease or illness, and those undergoing procedures associated with sedation, analgesia and anesthesia.

OBJECTIVE:

To describe the clinical characteristics and management of hospitalized OSA patients in Canada.

METHODS:

Using the Canadian Institute for Health Information’s hospital Discharge Abstract Database (fiscal year 2006/2007), a retrospective cohort study of all acute care patients discharged with a diagnosis that included OSA was performed.

RESULTS:

An examination of the discharge data of 2,400,245 acute care hospital abstracts identified 8823 cases of OSA. The mean age of OSA patients was 45.7 years and 66.5% were men. The most common comorbidities in the adult OSA population were obesity, cardiovascular disease, type 2 diabetes mellitus and chronic obstructive pulmonary disease. In adult OSA patients, the reported surgical intervention rate using uvulopalatopharyngoplasty (9.6%) was much higher than interventional CPAP therapy (4.8%).

CONCLUSIONS:

Only a small percentage of hospitalized OSA patients were documented as having received CPAP therapy during their stay. Issues relating to the accuracy, specificity and completeness of the Canadian Institute for Health Information’s hospital Discharge Abstract Database specific to OSA and its management were identified. Practices pertaining to the reporting, coding and management of hospitalized adult OSA patients warrant further investigation and research.     

Hemodynamic Effects of Noninvasive Ventilation in Patients with Venocapillary Pulmonary Hypertension

Background

The hemodynamic effects of noninvasive ventilation with positive pressure in patients with pulmonary hypertension without left ventricular dysfunction are not clearly established.

Objectives

Analyze the impact of increasing airway pressure with continuous positive airway pressure on hemodynamic parameters and, in particular, on cardiac output in patients with variable degrees of pulmonary hypertension.

Methods

The study included 38 patients with pulmonary hypertension caused by mitral stenosis without left ventricular dysfunction or other significant valvulopathy. The hemodynamic state of these patients was analyzed in three conditions: baseline, after continuous positive pressure of 7 cmH₂O and, finally, after pressure of 14 cmH₂O.

Results

The population was composed of predominantly young and female individuals with significant elevation in pulmonary arterial pressure (mean systolic pressure of 57 mmHg). Of all variables analyzed, only the right atrial pressure changed across the analyzed moments (from the baseline condition to the pressure of 14 cmH₂O there was a change from 8 ± 4 mmHg to 11 ± 3 mmHg, respectively, p = 0.031). Even though there was no variation in mean cardiac output, increased values in pulmonary artery pressure were associated with increased cardiac output. There was no harmful effect or other clinical instability associated with use application of airway pressure.

Conclusion

In patients with venocapillary pulmonary hypertension without left ventricular dysfunction, cardiac output response was directly associated with the degree of pulmonary hypertension. The application of noninvasive ventilation did not cause complications directly related to the ventilation systems.     

In patients with minimally symptomatic OSA can baseline characteristics and early patterns of CPAP usage predict those who are likely to be longer-term users of CPAP

Background

Long-term continuous positive airway pressure (CPAP) usage varies between individuals. It would be of value to be able to identify those who are likely to benefit from CPAP (and use it long term), versus those who would not, and might therefore benefit from additional help early on. First, we explored whether baseline characteristics predicted CPAP usage in minimally symptomatic obstructive sleep apnoea (OSA) patients, a group who would be expected to have low usage. Second, we explored if early CPAP usage was predictive of longer-term usage, as has been shown in more symptomatic OSA patients.

Methods

The MOSAIC trial was a multi-centre randomised controlled trial where minimally symptomatic OSA patients were randomised to CPAP, or standard care, for 6 months. Here we have studied only those patients randomised to CPAP treatment. Baseline characteristics including symptoms, questionnaires [including the Epworth sleepiness score (ESS)] and sleep study parameters were recorded. CPAP usage was recorded at 2–4 weeks after initiation and after 6 months. The correlation and association between baseline characteristics and 6 months CPAP usage was assessed, as was the correlation between 2 and 4 weeks CPAP usage and 6 months CPAP usage.

Results

One hundred and ninety-five patients randomised to CPAP therapy had median [interquartile range (IQR)] CPAP usage of 2:49 (0:44, 5:13) h:min/night (h/n) at the 2–4 weeks visit, and 2:17 (0:08, 4:54) h/n at the 6 months follow-up visit. Only male gender was associated with increased long-term CPAP use (male usage 2:56 h/n, female 1:57 h/n; P=0.02). There was a moderate correlation between the usage of CPAP at 2–4 weeks and 6 months, with about 50% of the variability in long-term use being predicted by the short-term use.

Conclusions

In patients with minimally symptomatic OSA, our study has shown that male gender (and not OSA severity or symptom burden) is associated with increased long-term use of CPAP at 6 months. Although, in general, early patterns of CPAP usage predicted longer term use, there are patients in whom this is not the case, and patients with low initial usage may need to extend their CPAP trial before a decision about longer-term use is made.