Continuous nasal positive airway pressure with a mouth leak: effect on nasal mucosal blood flux and nasal geometry

Effects of heated humidification on positive airway pressure side effects in patients with obstructive sleep apnoea: a meta-analysis

PURPOSE

An earlier study found that heated humidification reduced the side effects of positive airway pressure (PAP) in patients with obstructive sleep apnoea (OSA). However, other studies disagreed with this finding. Therefore, we evaluated the relationship between heated humidification and the side effects of PAP in patients with OSA.

METHODS

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, six databases were searched for relevant randomised controlled trials (RCTs) performed from January 1999 to June 2021.

RESULTS

From 1012 retrieved articles, we identified 9 eligible RCTs. Compared to the control group, the heated humidification group reported improvements in dry nose (pooled standardised mean difference [SMD] =  - 0.70, 95% confidence interval [CI] =  - 0.96 to - 0.45, I² = 0%, p < 0.00001), blocked nose (SMD =  - 0.47, 95%CI - 0.69 to - 0.25, I² = 36%, p < 0.0001), runny nose (SMD =  - 0.22, 95%CI - 0.44 to 0, I² = 0%, p = 0.05), dry mouth (SMD =  - 0.62, 95%CI - 0.87 to - 0.37, I² = 0%, p < 0.00001), and dry throat (SMD =  - 0.61, 95%CI - 0.90 to - 0.33, I² = 41%, p < 0.0001), but did not enhance positive airway pressure adherence (pooled mean difference [MD] = 0.24, 95% CI - 0.10 to 0.58, I² = 0%, p = 0.17).

CONCLUSIONS

Heated humidification improved some PAP side effects in patients with OSA but did not increase PAP adherence. Additional large-scale multi-centre RCTs are needed to verify the long-term effects.

Hypopharynx, oropharynx morphology and histology in severe Coronavirus 2 patients treated by noninvasive ventilation: comparison between full-face mask and helmet strategies

BACKGROUND

Non-invasive ventilation may alter the morphology and histology of the upper airway mucosa. This study aimed to investigate the alterations of hypopharynx and oropharynx mucosa, identified during oro-tracheal intubation procedure via video-assisted laryngoscopy, in severe acute respiratory syndrome Coronavirus 2 related, treated by non-invasive ventilation via full-face mask or helmet.

METHODS

Data of patients affected by Coronavirus 2 admitted to COVID Hospital of L'Aquila (Italy), presenting hypopharynx and oropharynx morphology alterations, requiring oro-tracheal intubation for invasive ventilation and initially treated with non-invasive ventilation were included in the study. The study aimed to investigate the upper airway mucosa alterations using oropharyngeal and hypopharyngeal images and biopsies taken during video-assisted-laryngoscopy. Data from the hypopharynx and oropharynx morphology and histology alterations between non-invasive ventilation via a full-face mask or helmet used during hospitalization were compared.

RESULTS

From 220 data recorded, 60 patients were included in the study and classified into non-invasive ventilation full-face mask group (30/60) and via helmet group. Comparing data between groups, significant differences were found with respect to hyperemia (77% vs. 20%), laryngeal bleeding ulcerations (87% vs. 13%), and vocal cord edema with >50% narrowing of the tracheal lumen (73% vs. 7%), respectively. The histology examination revealed fibrin-necrotic exudate with extensive necrotic degenerative changes in the sample tissue of the groups. There were not any differences in the duration time of non-invasive ventilation, time from hospitalization and the start of ventilation between groups.

CONCLUSIONS

The data from this research suggested that there were differences in airway mucosa damages among patients treated with a full-face mask or helmet. Further studies should be planned to understand which non-invasive ventilation support may mitigate upper airway mucosa damages when oro-tracheal intubation is requested for invasive respiratory support.

Practice recommendations for the role of physiotherapy in the management of sleep disorders: the 2022 Brazilian Sleep Association Guidelines

This clinical guideline supported by the Brazilian Sleep Association comprises a brief history of the development of Brazilian sleep physiotherapy, outlines the role of the physiotherapist as part of a sleep health team, and describes the clinical guidelines in respect of the management of some sleep disorders by the physiotherapist (including sleep breathing disorders, i.e., obstructive sleep apnea, central sleep apnea, upper airway resistance syndrome, hypoventilation syndromes and overlap syndrome, and pediatric sleep breathing disorders; sleep bruxism; circadian rhythms disturbances; insomnia; and Willis-Ekbom disease/periodic limb movement disorder. This clinical practice guideline reflects the state of the art at the time of publication and will be reviewed and updated as new information becomes available.

THE DETECTION AND ESTIMATION OF THE AIR LEAKAGE IN NONINVASIVE VENTILaTION: PLATFORM STUDY

Although noninvasive ventilation has been increasingly used in clinics and homes to treat respiratory diseases, the problem of air leaks should not be neglected because they may affect the performance of the ventilation and even pose a threat to life. The detection and estimation of the leakage are required to implement auto-compensation, which is important in the development of intelligent ventilation. In this study, the methods of detection and estimation of the leakage were established and validated. Ventilation experiments were performed based on the established experimental platform. The air flow and pressure were detected at different locations of the airway to determine the relationship between the leakage and the other variables. The leakage was estimated using linear predictor models. The curves describing the relationships among pressure, flow and volume changed regularly with the leakage. For pressure-controlled ventilation, the leakage could be estimated by the detected peak flow and by the ventilation volume of one breathing cycle. The methods for the leakage estimation were validated. Volume-controlled ventilation was also studied. Although the leakage could be estimated using the detected peak pressure, the limitation of volume-controlled ventilation was obvious for noninvasive ventilation (NIV). Leaks could be detected and estimated using a linear predictor model via the flow/pressure curve. The use of this model is a potential method for the auto-compensation of noninvasive ventilation.

Ventilator- and interface-related factors influencing patient-ventilator asynchrony during noninvasive ventilation

Patient-ventilator asynchrony (PVA) is common in patients receiving noninvasive ventilation (NIV). This occurs primarily when the triggering and cycling-off of ventilatory assistance are not synchronized with the patient's inspiratory efforts and could result in increased work of breathing and niv failure. In general, five types of asynchrony can occur during NIV: ineffective inspiratory efforts, double-triggering, auto-triggering, short-ventilatory cycling, and long-ventilatory cycling. Many factors that affect PVA are mostly related to the degree of air leakage, level of pressure support, and the type and properties of the interface used. Careful monitoring and adjustment of these factors are essential to reduce PVA and improve patient comfort. In this article, we discuss the machine and interface-related factors that influence PVA during NIV and its effect on the respiratory mechanics during pressure support ventilation, which is the ventilatory mode used most commonly during NIV. For that, we critically evaluated studies that assessed ventilator- and interface-related factors that influence PVA during NIV and proposed therapeutic solutions.

The effects of heated humidification to nasopharynx on nasal resistance and breathing pattern

Background

Mouth breathing could induce not only dry throat and eventually upper respiratory tract infection, but also snoring and obstructive sleep apnea, while nasal breathing is protective against those problems. Thus, one may want to explore an approach to modify habitual mouth breathing as preferable to nasal breathing. The aim of this study was to investigate the physiological effects of our newly developed mask on facilitation of nasal breathing.

Methods

Thirty seven healthy male volunteers were enrolled in a double blind, randomized, placebo-controlled crossover trial. Participants wore a newly developed heated humidification mask or non-heated-humidification mask (placebo) for 10-min each. Subjective feelings including dry nose, dry throat, nasal obstruction, ease to breathe, relaxation, calmness, and good feeling were asked before and after wearing each mask. In addition, the effects of masks on nasal resistance, breathing pattern, and heart rate variability were assessed.

Results

Compared with the placebo mask, the heated humidification mask improved all components of subjective feelings except for ease to breathe; moreover, decreased nasal resistance and respiratory frequency accompanied a simultaneous increase in a surrogate maker for tidal volume. However, use of the heated humidification mask did not affect heart rate variability

Conclusion

Adding heated humidification to the nasopharynx could modulate breathing patterns with improvement of subjective experience and objective nasal resistance.

Heated humidification did not improve compliance of positive airway pressure and subjective daytime sleepiness in obstructive sleep apnea syndrome: A meta-analysis

Introduction

We performed a meta-analysis on whether heated humidification during positive airway pressure (PAP) could improve compliance and subjective daytime sleepiness in obstructive sleep apnea syndrome (OSAS) patients.

Materials and methods

We searched PubMed, EMBASE, Medline, Cochrane Library, Clinical Trials, Web of Science and Scopus from inception to Oct 29, 2017. We made meta-analysis on the all available randomized controlled trials (RCTs) which assessed effects of heated humidification intervention on PAP compliance and subjective daytime sleepiness, by subgroups of automatic adjusting positive airway pressure/ continuous positive airway pressure (APAP/CPAP) usage and patients with/without upper airway symptoms prior to PAP therapy.

Results

A total of nine RCTs were evaluated finally in this meta-analysis. When all the studies were pooled, heated humidification did not improve PAP usage time [weighted mean difference(WMD) = 13.28, 95% confidence interval(CI): -5.85 to 32.41, P = 0.17] or Epworth sleepiness scale (ESS) score (WMD = -0.63, 95% CI: -1.32 to 0.07, P = 0.08). In terms of PAP usage time, heated humidification failed to enhance compliance in both APAP (WMD = 22.34, 95%CI: -21.08 to 65.77, P = 0.31) or CPAP subgroup (WMD = 11.09, 95%CI: -10.21 to 32.40, P = 0.31) and it was also ineffective among patients with upper airway symptoms prior to PAP therapy (WMD = 22.74, 95% CI: -7.77 to 53.24, P = 0.14) or without (WMD = 13.22, 95%CI: -35.84 to 62.29, P = 0.60). In terms of ESS score, heated humidification did not reduce ESS scores in both APAP (WMD = -1.59, 95% CI: -3.81 to 0.64, P = 0.16) or CPAP subgroup (WMD = -0.39, 95% CI: -1.16 to 0.37, P = 0.32) and it was also helpless among patients with upper airway symptoms prior to PAP therapy (WMD = -1.17, 95% CI: -3.10 to 0.75, P = 0.23) or without (WMD = -0.30, 95%CI: -2.25 to 1.66, P = 0.76).

Conclusion

Heated humidification during PAP therapy improves neither the compliance nor ESS scores in OSAS patients, no matter what types of PAP or whether the patients had upper airway symptoms prior to PAP therapy. But to the population with upper airway symptoms and the APAP users, the conclusions were limited because of small sample size and possible selection bias. More attentions should be paid to these potentially possible benefited subgroups.

The effect of continuous positive airway pressure therapy on nasal patency

BACKGROUND

Nasal congestion and obstruction are reported in the majority of continuous positive airway pressure (CPAP) users and are frequently cited as reasons for noncompliance. To our knowledge, no study has demonstrated a change in objective or subjective nasal patency in patients with obstructive sleep apnea (OSA) after a therapeutic trial of CPAP therapy.

METHODS

This prospective nonrandomized trial tested the hypothesis that CPAP therapy would result in both objective and subjective improvements in nasal patency in patients with OSA. Prior to initiation of CPAP, acoustic rhinometry (AR) was used to determine nasal volume and minimum cross-sectional area in the upright and reclined positions. Subjective nasal patency was assessed with the Nasal Obstruction Symptom Evaluation (NOSE) questionnaire. Both assessments were repeated at follow-up visits.

RESULTS

AR data demonstrated a statistically significant increase in total nasal volume (TV) in the reclined position (p = 0.002) and minimum cross-sectional area (MCA) in both the sitting and reclined positions (p = 0.006, p = 0.021) in OSA patients after >30 days of CPAP therapy and with >70% compliance. NOSE scores decreased significantly (p = 0.038) representing an improvement in nasal patency.

CONCLUSION

Objective and subjective measurements of TV and MCA increased after initiation of CPAP therapy in this prospective study.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Factors Contributing to Unintentional Leak During CPAP Treatment: A Systematic Review

CPAP is the first-line treatment for moderate to severe OSA syndrome. Up to 25% of patients with OSA syndrome discontinue CPAP treatment due to side effects. Unintentional leakage and its associated annoying consequences are the most frequently reported adverse effects of CPAP. Successive technological improvements have not succeeded in addressing this issue. A systematic review was conducted (1) to assess the impact of different technological advances on unintentional leaks and (2) to determine if any patient characteristics have already been identified as determinants of unintentional leakage. No CPAP modality was superior to another in reducing unintentional leaks and, surprisingly, oronasal masks were associated with higher unintentional leaks. Nasal obstruction, older age, higher BMI, central fat distribution, and male sex might be associated with an increased risk of unintentional leakage. Such leaks remain an important problem. Further studies are needed to improve the understanding of underlying clinical factors so that patients at risk of unintentional leaks may be identified and individualized solutions applied.

Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air

Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA.

Clinical review: humidifiers during non-invasive ventilation--key topics and practical implications

Inadequate gas conditioning during non-invasive ventilation (NIV) can impair the anatomy and function of nasal mucosa. The resulting symptoms may have a negative effect on patients' adherence to ventilatory treatment, especially for chronic use. Several parameters, mostly technical aspects of NIV, contribute to inefficient gas conditioning. Factors affecting airway humidity during NIV include inspiratory flow, inspiratory oxygen fraction, leaks, type of ventilator, interface used to deliver NIV, temperature and pressure of inhaled gas, and type of humidifier. The correct application of a humidification system may avoid the effects of NIV-induced drying of the airway. This brief review analyses the consequences of airway dryness in patients receiving NIV and the technical tools necessary to guarantee adequate gas conditioning during ventilatory treatment. Open questions remain about the timing of gas conditioning for acute or chronic settings, the choice and type of humidification device, the interaction between the humidifier and the underlying disease, and the effects of individual humidification systems on delivered humidity.

Routine use of humidification with nasal continuous positive airway pressure

BACKGROUND

Heated humidification can reduce nasal symptoms caused by continuous positive airway pressure (CPAP) treatment, but its routine use has not been studied over the medium term in a randomized controlled trial. The aim of this study is to determine if heated humidification would reduce nasal symptoms and improve adherence with CPAP treatment in all patients with sleep apnoea irrespective of whether they had nasal symptoms initially.

METHODS

A randomized, parallel group design. Patients were treated for 3 months with a Fisher & Paykel HC201 pump with built-in heated humidification, or with the heater disabled and without water. Adherence was measured with a timer built into the pumps. Nasal symptoms were measured with a 10-cm visual analogue scale.

RESULTS

There were 25 in the humidification group and 29 in the non-humidification group. After 12 weeks mean (standard deviation) adherence with CPAP was 4.7 (2.4) and 4.5 (2.2) hours per night respectively. Nasal symptoms that were reduced were nose blocked* 6 (12), 18 (26); sneezing* 4 (8), 15 (25); dry nose* 8 (12), 24 (33); stuffy nose* 7 (14), 22(31); dry mouth* 13 (18), 33(36); and runny nose* 6 (17), 14 (29). Parameters marked with an asterisk '*' had P < 0.05 with t-tests.

CONCLUSION

The routine use of heated humidification with CPAP in all patients with sleep apnoea reduced nasal symptoms, but did not improve adherence.

Effects of heated humidification on nasal inflammation in a CPAP rat model

BACKGROUND

Rhinitis is a potential side effect of nasal continuous positive airway pressure (nCPAP). Heated Humidification (HH) is applied to treat rhinitic symptoms, but its usefulness is controversial. Confounding factors such as previous rhinitis or nasal obstruction make it difficult to draw definitive conclusions. Animal models could therefore be useful.

OBJECTIVES

To study the effects of HH as a mechanism that may reduce nasal inflammation during nCPAP application in the presence or absence of an oral leak (OL).

METHODS

Prospective controlled animal study. Setting I: Sixty Sprague-Dawley rats were distributed into noCPAP (naïve), sham-CPAP with HH, 5 and 10cm H(2)O nCPAP, and 10cm H(2)O nCPAP with HH for 5h. Setting II: Thirty-three rats were exposed to nCPAP, nCPAP with a controlled OL, and nCPAP with controlled OL and HH (n=11 each). The degree of nasal inflammation was assessed by directly evaluating the percentage of neutrophils in the nasal mucosa.

RESULTS

Percentage of neutrophils was higher after 5h of 10cm nCPAP compared to the control group (0.96+/-0.26% vs. 0.18+/-0.05%; p=0.001). When HH was applied, the percentage of neutrophils did not differ from that observed in the nCPAP group. The addition of a controlled OL, did not show significant differences in the neutrophils count compared to nCPAP alone (0.75+/-0.19% vs. 0.83+/-0.29%; p=0.70). Moreover, the application of HH to the rat with OL did not change the percentage of neutrophils.

CONCLUSIONS

HH applied to an acute rat model of nCPAP with and without a controlled OL does not seem to reduce nasal inflammation.

Vocal changes in patients using nasal continuous positive airway pressure

The aim of this prospective study is to assess the vocal changes in patients using nasal continuous positive airway pressure (CPAP). A total of 18 subjects using nasal CPAP were assessed by grading their voice perceptually as G0 for normal voice and G3 for severe hoarseness. Acoustic analysis was also performed and the following parameters were measured: fundamental frequency, habitual pitch, shimmer, relative average perturbation, voice turbulence index, and noise-to-harmonic ratio. The same was done for a control group matched according to age and gender. There was a statistically significant difference in the perceptual evaluation between the CPAP group and controls, with more patients in the former group having moderate hoarseness. There was also an increase in the perturbation parameters and a decrease in the fundamental frequency and habitual pitch in the CPAP group compared to controls. The increase in shimmer was statistically significant. The usage of nasal CPAP seems to induce vocal changes that are perceived as mild to moderate hoarseness, together with an increase in the perturbation parameters. These seem to be secondary to the upper airway dryness reported in these patients. The hypothetical effect of nasal CPAP on the sol layer of the vocal folds is discussed.

Effect of changing airway pressure on the ability of the human nose to warm and humidify air

OBJECTIVES

Nasal continuous positive airway pressure (CPAP) treatment causes nasal symptoms that are believed to result from the drying effects of the air on the nasal mucosa, and these symptoms affect compliance with therapy. We hypothesized that the increased air pressure on the nasal mucosa caused by positive pressure from CPAP would decrease the ability of the nose to warm and humidify inspired air, explaining these symptoms.

METHODS

We performed a 4-way crossover trial using CPAP pressures of -5, 0, +5, and +10 cm H2O in 10 subjects. The ability to warm and humidify inspired air was determined by measurement of the temperature of a fixed volume of cold, dry air entering and exiting the nostril and calculation of the amount of water supplied to the airstream by the nose.

RESULTS

The water content of air was unaffected at the pressures studied.

CONCLUSIONS

The pressure of delivered CPAP does not affect the ability of the nose to warm and humidify inspired air.

Adherence to continuous positive airway pressure therapy: the challenge to effective treatment

Despite the high efficacy of continuous positive airway pressure (CPAP) to reverse upper airway obstruction in sleep apnea, treatment effectiveness is limited by variable adherence to prescribed therapy. When adherence is defined as greater than 4 hours of nightly use, 46 to 83% of patients with obstructive sleep apnea have been reported to be nonadherent to treatment. Evidence suggests that use of CPAP for longer than 6 hours decreases sleepiness, improves daily functioning, and restores memory to normal levels. The decision to embrace CPAP occurs during the first few days of treatment. Although many strategies in patient interface with CPAP or machine modality are marketed to improve CPAP usage, there are few data to support this. No single factor has been consistently identified as predictive of adherence. Patient perception of symptoms and improvement in sleepiness and daily functioning may be more important in determining patterns of use than physiologic aspects of disease severity. Emerging data suggest that various behavioral interventions may be effective in improving CPAP adherence.

Effect of a heated humidifier during continuous positive airway pressure delivered by a helmet

Introduction

The helmet may be an effective interface for the delivery of noninvasive positive pressure ventilation. The high internal gas volume of the helmet can act as a 'mixing chamber', in which the humidity of the patient's expired alveolar gases increases the humidity of the dry medical gases, thus avoiding the need for active humidification. We evaluated the temperature and humidity of respiratory gases inside the helmet, with and without a heated humidifier, during continuous positive airway pressure (CPAP) delivered with a helmet.

Methods

Nine patients with acute respiratory failure (arterial oxygen tension/fractional inspired oxygen ratio 209 ± 52 mmHg) and 10 healthy individuals were subjected to CPAP. The CPAP was delivered either through a mechanical ventilator or by continuous low (40 l/min) or high flow (80 l/min). Humidity was measured inside the helmet using a capacitive hygrometer. The level of patient comfort was evaluated using a continuous scale.

Results

In patients with acute respiratory failure, the heated humidifier significantly increased the absolute humidity from 18.4 ± 5.5 mgH₂O/l to 34.1 ± 2.8 mgH₂O/l during ventilator CPAP, from 11.4 ± 4.8 mgH₂O/l to 33.9 ± 1.9 mgH₂O/l during continuous low-flow CPAP, and from 6.4 ± 1.8 mgH₂O/l to 24.2 ± 5.4 mgH₂O/l during continuous high-flow CPAP. Without the heated humidifier, the absolute humidity was significantly higher with ventilator CPAP than with continuous low-flow and high-flow CPAP. The level of comfort was similar for all the three modes of ventilation and with or without the heated humidifier. The findings in healthy individuals were similar to those in the patients with acute respiratory failure.

Conclusion

The fresh gas flowing through the helmet with continuous flow CPAP systems limited the possibility to increase the humidity. We suggest that a heated humidifier should be employed with continuous flow CPAP systems.

Evidence of interrelated side effects with reduced compliance in patients treated with nasal continuous positive airway pressure

OBJECTIVES

Patients treated for obstructive sleep apnea syndrome (OSAS) with nasal continuous positive airway pressure (nCPAP) often have side effects and poor compliance. Our objectives were to explore their side effects when treated with nCPAP and to validate the association of a side effect syndrome with the outcomes of sleep quality, daytime sleepiness and nCPAP compliance.

METHODS

Prospective exploratory and subsequent validation study using questionnaires was performed in a tertiary-care sleep-disorders clinic. Consecutive patients with polysomnographic diagnosis and nCPAP titrations treated at least 3 months with single-pressure nCPAP were studied. In the first survey, 114 patients were questioned of whom 89 (78%) qualified for exploratory analysis. In the validation survey of 122 patients, 104 (85%) were studied. Subjects were interviewed and their nCPAP meters were queried.

RESULTS

In the first survey, 3 side effects were often found together and each found to be correlated to compliance: mouth leak with nCPAP, nasal congestion, and taking off the mask prematurely. In the validation study, 34% of participants met a syndrome definition with at least 2 of 3 major side effects. Mean (SD) compliance was lower in patients with the syndrome: 4.97 (1.98) vs. 6.42 (1.56) hours per night (p=0.0001). Poor sleep quality and lower satisfaction with nCPAP were associated with the syndrome.

CONCLUSIONS

The syndrome of mouth leak, taking off the nCPAP mask prematurely and nasal congestion is frequent in patients treated with nCPAP. This is associated with lower compliance and poor sleep quality.

Effects of nasal mask leak and heated humidification on nasal mucosa in the therapy with nasal continuous positive airway pressure (nCPAP)

The purpose of this study was to determine the objective short-term influence of nasal continuous positive airway pressure (nCPAP) therapy, nasal mask leak (NML) and heated humidifiers (HH) to nasal conditioning of spontaneously breathing subjects. This was a prospective, non-randomized, non-blinded day-time study. Eighteen healthy subjects were enrolled in the study. All subjects received nCPAP therapy for 60 min in three different conditions successively: (1) nCPAP without humidification, (2) nCPAP with a defined leakage of nasal mask (slashed circle 28.3 mm2) and (3) nCPAP with HH. Nasal humidity and temperature were measured in the anterior turbinate area using a miniaturized thermocouple and a relative humidity sensor. The measurements were accomplished at the beginning of therapy, after 60, 120 and 180 min. Absolute humidity (aH) in the anterior turbinate area decreased significantly (p = 0.0075) from 17.41 +/- 3.81 mg/l (baseline) to 15.27 +/- 2.21 mg/l (nCPAP alone). With attachment of a NML, aH decreased from 15.27 mg/l not significantly (p = 0.058) to 13.77 +/- 2.28 mg/l (nCPAP and NML) compared to nCPAP alone. After addition of heated humidification to nCPAP, aH increased again from 13.77 mg/l significantly (p = 0.042) to 15.29 +/- 3.51 mg/l (nCPAP and HH) compared to aH (nCPAP+NML). No difference was found between aH (nCPAP and HH) and aH (nCPAP alone). Airway temperature did not change significantly after application of nCPAP alone, nCPAP and NML, and nCPAP and HH. These data indicate that nCPAP therapy with NML tends to have more remarkable reduction of the nasal humidity than nCPAP therapy without NML. nCPAP with heated humidifier is able to compensate the dehydration effects induced by nCPAP therapy with NML by increasing the aH at the anterior turbinate area to the levels observed during breathing with nCPAP alone.

Mouth breathing in obstructive sleep apnea prior to and during nasal continuous positive airway pressure

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) often complain of dryness of mouth and throat prior to and during nasal continuous positive airway pressure (nCPAP). It is believed that this is due to mouth breathing (MB). However, the association between mouth breathing and apneas/hypopneas and the effect of CPAP on MB has not been studied.

OBJECTIVES

The purpose of the present study was, therefore, to assess the frequency and duration of episodes of MB prior to and during treatment with nCPAP.

METHODS

MB was recorded prior to and during nCPAP with a closely fitting mouth mask connected to a pneumotachograph and nasal flow was measured via nasal prongs. MB episodes were expressed as the number of events divided by total sleep time x 60, to give the MB event index per hour of sleep. MB time divided by total sleep time x 60 was calculated in minutes to get the MB time index per hour of sleep.

PATIENTS

Eleven male patients with OSAS (mean age 57.9 +/- 8.3 years, body mass index 30.2 +/- 3.8) were recruited to the study.

RESULTS

Prior to nCPAP, the apnea/hypopnea index was 55.8 +/- 26 and decreased during nCPAP to 8.0 +/- 3.4. The lowest SaO2 measured was 82.9 +/- 4.7%, and increased to 87.5 +/- 2.7% under nCPAP. The mean nCPAP was 7.8 +/- 1.6 cm H2O. MB event index per hour of sleep decreased from 35.2 +/- 19.7 prior to treatment to 5.0 +/- 5.2 under nCPAP (p < 0.01). In 52.2 +/- 27.4% of obstructive respiratory events, MB started at the end of an apnea/hypopnea episode, decreasing to 8.5 +/- 12.5% with nCPAP treatment. MB time index per hour of sleep was reduced from 13.5 +/- 10.2 min prior to treatment to 4.6 +/- 5.5 min under nCPAP (p < 0.05).

CONCLUSIONS

In OSAS patients, MB episodes often appear at the termination of an apnea/hypopnea episode. In many cases, MB episodes can be markedly reduced by nCPAP treatment. When patients on nCPAP complain of dry mouth, appropriate measurements should be performed to verify MB.

How does open-mouth breathing influence upper airway anatomy?

OBJECTIVES/HYPOTHESIS

Open-mouth breathing during sleep may increase the severity of obstructive sleep apnea (OSA) and complicate nasal continuous positive airway pressure (CPAP) therapy in patients with OSA. The aim of this study was to assess the effect of open-mouth breathing on upper airway anatomy using lateral cephalometry and fiberoptic nasopharyngoscopy.

STUDY DESIGN

This was a cross-sectional study.

METHODS

Lateral cephalometry and fiberoptic nasopharyngoscopy were carried out on 28 subjects with a mean age of 36.7 years. We compared the effect of the mouth being open or closed on the results in lateral cephalometry (pharyngeal length, distance between the mandible and hyoid bone [MP-H], angles from the sella-nasion to mandibular points A and B [SNA, SNB, respectively], retropalatal, retroglossal, and hypopharyngeal distance) and fiberoptic nasopharyngoscopy (retropalatal and retroglossal cross-sectional area).

RESULTS

On lateral cephalometric measurements, retropalatal distance (P = .000), retroglossal distance (P = .000), and MP-H (P = .002) were lower with mouth open, and pharyngeal length (P = .000) was greater. However, there were no significant differences in SNA and hypopharyngeal distance. On fiberoptic nasopharyngoscopy, retropalatal (P = .005) and retroglossal (P = .000) cross-sectional areas were significantly reduced with the mouth open.

CONCLUSIONS

Open-mouth breathing is associated with reduction of the retropalatal and retroglossal areas, lengthening of the pharynx and shortening of the MP-H in the upper airway. We suggest that knowledge of these anatomic changes improves our understanding of the increase of OSA severity and the low adherence to nasal CPAP therapy in mouth breathers.

The effect of mouth leak and humidification during nasal non-invasive ventilation

BACKGROUND

Poor mask fit and mouth leak are associated with nasal symptoms and poor sleep quality in patients receiving domiciliary non-invasive ventilation (NIV) through a nasal mask. Normal subjects receiving continuous positive airways pressure demonstrate increased nasal resistance following periods of mouth leak. This study explores the effect of mouth leak during pressure-targeted nasal NIV, and whether this results in increased nasal resistance and consequently a reduction in effective ventilatory support.

METHODS

A randomised crossover study of 16 normal subjects was performed on separate days. Comparison was made of the effect of 5 min of mouth leak during daytime nasal NIV with and without heated humidification. Expired tidal volume (V(T)), nasal resistance (R(N)), and patient comfort were measured.

RESULTS

Mean change (Delta) in V(T) and R(N) were significantly less following mouth leak with heated humidification compared to the without (DeltaV(T) -36+/-65 ml vs. -88+/-50 ml, p<0.001; DeltaR(N) +0.9+/-0.4 vs. +2.0+/-0.7 cm H(2)O l s(-1), p<0.001). Baseline comfort was worse without humidification (5.3+/-0.4 vs. 6.2+/-0.4, p<0.01), and only deteriorated following mouth leak without humidification.

CONCLUSIONS

In normal subjects, heated humidification during nasal NIV attenuates the adverse effects of mouth leak on effective tidal volume, nasal resistance and improves overall comfort. Heated humidification should be considered as part of an approach to patients who are troubled with nasal symptoms, once leak has been minimised.

The acute impact of continuous positive airway pressure on nasal resistance: a randomized controlled comparison

Subjective nasal obstruction is common among users of continuous positive airway pressure (CPAP). The aim of this study was to measure the acute effect of CPAP on nasal resistance and nasal symptoms in awake normal subjects. Twenty-four healthy CPAP-naive adults [8 men, 16 women; mean age 30 yr (SD 14)] underwent a randomized controlled crossover study comparing nasal CPAP (8 cmH(2)O) for 6 h on one occasion and the control condition (nasal mask without CPAP) on the other. Nasal resistance measurements (posterior active rhinometry) before and after the test exposure were similar on both test days. Nasal resistance during CPAP exposure [2.04 cmH(2)O.l(-1).s (SD 0.72)] was significantly lower than that of the control [2.67 cmH(2)O.l(-1).s (SD 1.07)]: mean difference 0.66 cmH(2)O.l(-1).s, 95% confidence interval 0.19-1.13 cmH(2)O.l(-1).s. The gradient in pressure from CPAP mask to posterior naris during CPAP exposure varied from 1.6 to 2 cmH(2)O but was not significantly different between time points. Subjective nasal symptom scores and peak nasal inspiratory flow rates did not change significantly on either test day. We conclude that in awake CPAP-naive normal subjects, acute CPAP exposure is associated with a reduction in nasal resistance compared with the control condition, but it is not associated with an immediate post-CPAP change in subjective or objective nasal resistance.

Pressure-relief continuous positive airway pressure vs constant continuous positive airway pressure: a comparison of efficacy and compliance

OBJECTIVES

To compare polysomnographic data and compliance in sleep apnea patients receiving continuous positive airway pressure (CPAP) and pressure-relief CPAP (PRCPAP) [C-flex; Respironics; Murrysville, PA] as first treatment in the sleep laboratory and subsequently at home.

DESIGN

A prospective, randomized, crossover design was used in the sleep laboratory, and a prospective randomized design was used at home.

PATIENTS

Data were collected from 52 sleep apnea patients for whom CPAP was used for the first time.

INTERVENTIONS

Treatment with constant CPAP and PRCPAP.

MEASUREMENTS AND RESULTS

Patients with a first-time diagnosis of obstructive sleep apnea syndrome (OSAS) underwent conventional CPAP titration. Thereafter, polysomnography was performed at the titrated pressure using both the fixed CPAP pressure mode and the PRCPAP mode in a randomized crossover approach. The patients were then discharged home for 7 weeks of treatment with the last-applied treatment mode, and compliance data were established at the end of that time. The average apnea-hypopnea index was 53.3/h in the "diagnostic night," 5.8/h with CPAP, and 7.0/h with PRCPAP. The native arousal index was 35.2/h, 12.6/h with CPAP, and 12.9/h with PRCPAP (not significant [NS]). The central apnea index was 0.7/h with CPAP and 1.2/h with PRCPAP (p < 0.05). Compliance after 7 weeks was, on average, 9.4 min longer with PRCPAP than with CPAP (NS). Evaluation of a 13-item questionnaire showed scores of 16.4 for PRCPAP and 18.1 for constant CPAP (NS) [the fewer the complaints, the lower the score]. With regard to oral dryness, the score with PRCPAP (1.4) was significantly lower than with constant CPAP (1.9) [p < 0.05]. This difference was no longer detectable after 7 weeks.

CONCLUSION

In terms of the effectiveness in treating obstructive sleep apnea, PRCPAP and constant CPAP are comparable. During the first night of treatment, patients receiving PRCPAP had less dryness of mouth; over a period of 7 weeks, this difference disappeared. Nightly use of the device was comparable in both groups. PRCPAP is therefore a new ventilation mode that enables effective treatment of OSAS patients. Further studies should be done to investigate the effects of expiratory pressure lowering in low-compliance patients and patients requiring CPAP > 9 cm H(2)O or experiencing dry mouth with CPAP.

Selective indication for positive airway pressure (PAP) in sleep-related breathing disorders with obstruction

Positive airway pressure (PAP) is the therapy of choice for most sleep-related breathing disorders (SRBD). A variety of PAP devices using positive airway pressure (CPAP, BiPAP, APAP, ASV) must be carefully considered before application. This overview aims to provide criteria for choosing the optimal PAP device according to severity and type of sleep-related breathing disorder. In addition, the range of therapeutic applications, constraints and side effects as well as alternative methods to PAP will be discussed. This review is based on an analysis of current literature and clinical experience. The data is presented from an ENT-sleep-laboratory perspective and is designed to help the ENT practitioner initiate treatment and provide support. Different titration methods, current devices and possible applications will be described. In addition to constant pressure devices (CPAP), most commonly used for symptomatic obstructive sleep apnoea (OSA) without complicating conditions, BiPAP models will be introduced. These allow two different positive pressure settings and are thus especially suitable for patients with cardiopulmonary diseases or patients with pressure intolerance, increasing compliance in this subgroup considerably. Compliance can also be increased in patients during first night of therapy, patients with highly variable pressure demands or position-dependent OSA, by using self-regulating Auto-adjust PAP devices (Automatic positive airway pressure, APAP). Patients with Cheyne-Stokes breathing, a subtype of central sleep apnoea, benefit from adaptive servo-ventilation (ASV), which analyzes breathing patterns continually and adjusts the actual ventilation pressure accordingly. This not only reduces daytime sleepiness, but can also influence heart disease positively. Therapy with positive airway pressure is very effective in eliminating obstruction-related sleep diseases and symptoms. However, because therapy is generally applied for life, the optimal PAP device must be carefully selected, taking into account side effects that influence compliance.

Effect of heated humidification on compliance and quality of life in patients with sleep apnea using nasal continuous positive airway pressure

STUDY OBJECTIVE

To determine whether the addition of heated humidification at treatment initiation with nasal continuous positive airway pressure (CPAP) would lead to better CPAP compliance and improve quality of life and subjective sleepiness in patients with sleep apnea.

DESIGN

Randomized controlled trial.

SETTING

An academic sleep center located at a Veterans Affairs hospital.

PATIENTS

Ninety-eight patients with obstructive sleep apnea who had not received nasal CPAP previously.

MEASUREMENTS AND RESULTS

Patients received heated humidification at CPAP initiation in the treatment group. In the control group, patients could receive heated humidification only if they had upper airway symptoms that could not be treated successfully with simpler measures. Patients were followed up at 1 month, 3 months, and 12 months. Outcome measures were compliance with nasal CPAP (mean hours per night at effective pressure), quality of life as measured by the Calgary sleep apnea quality of life index, subjective sleepiness measured with the Epworth sleepiness scale, and CPAP side effects. There was no difference in CPAP compliance between groups. Quality of life and subjective sleepiness improved in both groups with nasal CPAP therapy, but there was no difference in the extent of improvement between groups. The overall CPAP side effect score was similar in both groups, but individual symptoms of dry nose and dry mouth and throat were significantly lower in the heated humidification group.

CONCLUSIONS

The addition of heated humidification when nasal CPAP was instituted did not lead to better compliance, greater improvement in sleepiness, or improved quality of life, but was associated with fewer symptoms attributable to the upper airway.

[Leak monitoring in noninvasive ventilation]

Nasal mask ventilation has been shown to be effective, but outcomes do not always match expectations because of mouth leaks, patient-ventilator asynchrony, or decreased upper airway patency. These developments are detected when they lead ultimately to circuit leaks that lower the effectiveness of ventilation through pressure loss, poor inspiratory triggering, and prolonged inspiratory time. The quality of sleep is affected, and adverse effects and treatment intolerance may arise. A number of ways to detect leaks and their practical consequences are proposed in this article. We applied 310 leak-detection procedures to 177 patients who had disappointing clinical, gasometric, or polysomnographic outcomes of ventilation. The leak-detection procedures varied according to the type of ventilation and the supposed underlying pathophysiological mechanism. Significant leaks were detected in 132 patients (76%); therapeutic changes were then prescribed to optimize outcomes. We present a practical method to apply in patients with suboptimal ventilation outcomes. If leaks can be detected during treatment, the probable cause of treatment failure can sometimes be established and possible pathophysiological mechanisms better understood. With this knowledge, it may be possible to improve ventilation.

Non-invasive positive pressure ventilation in patients with acute respiratory failure

Non-invasive positive pressure ventilation is an emerging modality in contemporary critical care practice. Perhaps the most widely utilized and familiar form of non-invasive positive pressure ventilation is mask continuous positive airway pressure. Other common modes include mask Bi-level positive airway pressure and mask pressure support ventilation. All feature the delivery of positive airway pressure via a mask (full-face, naso-oral or nasal), and a patient-controlled respiratory cycle. The physiological benefits of non-invasive positive pressure ventilation suggested by a number of studies include improved oxygenation, decreased work of breathing, improved ventilation and perfusion matching, decreased fatigue, and increased minute ventilation. The utilization of non-invasive positive pressure ventilation has now been reported for a variety of clinical indications. In most, randomized trials are lacking, and the benefits and preferred mode of non-invasive positive pressure ventilation are still to be elucidated. In general, in patients that are candidates for endotracheal intubation, non-invasive positive pressure ventilation should be used as a way to possibly avoid endotracheal intubation rather than as an alternative to endotracheal intubation. Whilst the benefit of non-invasive positive pressure ventilation appears to be established in patients with chronic obstructive airways disease with hypercapnic acute respiratory failure, one of the major unresolved issues is whether one modality is significantly better than the others. Unfortunately, the question of whether Bi-level positive airway pressure is better than continuous positive airway pressure in this clinical scenario has not been satisfactorily addressed in any large randomized and controlled clinical trial. Further, there is no 'gold standard' for predicting success with non-invasive positive pressure ventilation, although several studies have looked at this aspect.

Predictive factors for the need for additional humidification during nasal continuous positive airway pressure therapy

OBJECTIVE

To identify potential risk factors for the need for an additional cold or heated humidifier in nasal continuous positive airway pressure (nCPAP) circuitry.

DESIGN

A prospective cohort study.

SETTING

University hospital sleep-disorders center.

PATIENTS

Eighty-two consecutive patients with obstructive sleep apnea syndrome were followed up for a median of 347 days (range, 3 to 530 days) after the initiation of nCPAP therapy.

MEASUREMENTS AND RESULTS

In 46 patients (56%), the occurrence of upper-airway symptoms led to the addition of a cold humidifier after a median time of 39 days (range, 2 to 94 days). In 23 of the 46 patients, the persistence of the symptoms indicated the secondary use of a heated humidifier after a median time of 28 days (range, 5 to 70 days). nCPAP use (mean +/- SD) was not influenced by cold humidification (4.58 +/- 2.05 h/d vs 4.7 +/- 2.48 h/d; p = 0.75), but it increased significantly with heated humidification (5.38 +/- 2.26 h/d vs 3.51 +/- 2.53 h/d; p < 0.01). Anthropometric characteristics, drying medications, clinical findings such as deformity of the nasal septum, symptoms of a chronic mucosa disease (CMD), a previous uvulopalatopharyngoplasty (UPPP), and polysomnographic parameters had no significant effect on the need for a cold humidifier. Age > 60 years (odds ratio [OR], 5.58; 95% confidence interval [CI], 1.69 to 18.43), drying medications (OR, 6.59; 95% CI, 1.29 to 33.51), presence of CMD (OR, 4.11; 95% CI, 1.24 to 13.58), and previous UPPP (OR, 4.56; 95% CI, 1.18 to 17.6) were found as significant risk factors for the addition of a heated humidifier.

CONCLUSION

Our results demonstrate that heated humidification significantly improves the nCPAP daily rate of use and that its need may be predicted.

In vivo efficacy of heated and non-heated humidifiers during nasal continuous positive airway pressure (nCPAP)-therapy for obstructive sleep apnoea

Upper airway dryness is a frequent side-effect of nasal continuous positive airway pressure therapy (nCPAP) in obstructive sleep apnoea (OSA). In this situation, heated or non-heated passover humidifiers are often added to the nCPAP-therapy. The efficacy of these two modes in terms of increasing the absolute humidity of the inspired air in vivo has so far not been established. The present investigation was therefore designed to compare various heated and non-heated passover humidifiers in terms of the their ability to increase the absolute humidity in the inspired air during nCPAP. In six healthy test individuals, nCPAP-therapy at pressures of 5 mbar and 10 mbar was simulated, and the relative humidity and temperature of the air within the tube at the junction between CPAP tube and mask were measured. In each test person, measurements were carried out both with and without the two heated (HC 100, Fischer&Paykel Inc., New Zealand and HumidAire, ResMed Ltd., Australia) and two non-heated (Oasis and Humidifier, both from Respironics Inc., U.S.A.) passover humidifiers under steady-state conditions. The absolute humidity was calculated from the relative humidity and temperature measurements. The mean (SD) absolute humidity (gm(-3)) in the steady-state was significantly (P<0.05 higher with each of the humidifiers than that calculated when no humidifier was used. The relevant figures were as follows: no humidifier: 10(-2) (1.8) gm(-3) (at 5 mbar)/9.8 (1.8) gm(-3) (at 10 mbar); Humidifier: 16.4 (0.97)/15.6 (1.26); Oasis: 17.3 (0.97)/ 16.7 (0.93); HC100: 26.5 (1.40)/26.2 (1.23); HumidAire: 31.8 (2.50)/30.9 (2.64). The mean increase in absolute humidity (in gm(-3)) with the aid of the heated humidifiers was 16.3 (5 mbar) gm(-3)/16.4 (10 mbar) gm(-3) with HC100 and 21.6/21.1 with HumidAire, and in both cases was clearly and significantly (P=0.028) higher in comparison with the non-heated humidifiers--6.2/5.8 with Humidifier and 7.2/6.9 with Oasis. In terms of the absolute humidity achieved within the CPAP tube system, the heated humidifiers were clearly superior to the non-heated humidifiers. These results were, however, obtained under laboratory conditions, and therefore cannot be translated unreservedly to the situation represented by long-term CPAP-treatment. Furthermore, it is possible that the smaller humidification capacity of the non-heated humidifiers may still suffice to meet the requirements of clinical use in terms of effectively preventing dry airways under CPAP treatment. This point, however, needs further investigation on the basis of long-term clinical studies.

Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy

STUDY OBJECTIVES

The objectives of this study were (1) to evaluate the way in which nasal continuous positive airway pressure (CPAP) therapy influences the relative humidity (rH) of inspired air; and (2) to assess the impact on rH of the addition of an integrated heated humidifier or a full face mask to the CPAP circuitry.

DESIGN

The studies were performed in 25 patients with obstructive sleep apnea syndrome receiving long-term nasal CPAP therapy and complaining of nasal discomfort. During CPAP administration, temperature and rH were measured in the mask either during a night's sleep for 8 patients or during a daytime study in which the effects of mouth leaks were simulated in 17 patients fitted with either a nasal mask (with or without humidification) or a face mask alone.

SETTING

University hospital sleep disorders center.

MEASUREMENTS AND RESULTS

Compared with the values obtained with CPAP alone, integrated heated humidification significantly increased rH during the sleep recording, both when the mouth was closed (60 +/- 14% to 81 +/- 14%, p < 0.01) and during mouth leaks (43 +/- 12% to 64 +/- 8%, p < 0.01). During the daytime study, a significant decrease in rH was observed with CPAP alone. Compared with the values measured during spontaneous breathing without CPAP (80 +/- 2%), the mean rH was 63 +/- 9% (p < 0.01) with the mouth closed and 39 +/- 9% (p < 0. 01) with the mouth open. The addition of heated humidification to CPAP prevented rH changes when the mouth was closed (82 +/- 12%), but did not fully prevent the rH decrease during simulation of mouth leaks (63 +/- 9%) compared with the control period (80 +/- 2%, p < 0. 01). Finally, attachment of a face mask to the CPAP circuitry prevented rH changes both with the mouth closed (82 +/- 9%) and with the mouth open (84 +/- 8%).

CONCLUSIONS

These data indicate that inhaled air dryness during CPAP therapy can be significantly attenuated by heated humidification, even during mouth leaks, and can be totally prevented by using a face mask.

Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure

STUDY OBJECTIVES

To evaluate the effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure (CPAP).

DESIGN

A randomized, crossover design was employed.

SETTING

The study was conducted at two suburban community-based hospital sleep laboratories.

PATIENTS

Data were collected on 38 obstructive sleep apnea patients (mean age, 44.1 years) in whom CPAP was a novel treatment.

INTERVENTIONS

The interventions were heated humidity, cold passover humidity, and a washout period without humidity.

MEASUREMENTS AND RESULTS

Patients were titrated with heated humidity or cold passover humidity in the laboratory and subsequently initiated on humidity. Objective compliance, self-report of factors affecting CPAP use, satisfaction with CPAP, feeling upon awakening, and daytime sleepiness were assessed at the completion of each 3-week treatment period and a 2-week washout period. Outcome measures were assessed with one-way analysis of variance followed by Scheffe post hoc comparisons. Significant main effects were observed for compliance (F2,37 = 5.2; p = 0.008), satisfaction with CPAP (F2,37 = 4.5; p = 0.01), and feeling refreshed on awakening (F2,37 = 4.4; p = 0.02). A significant decrease in daytime sleepiness was observed between baseline and each of the conditions (F3,37 = 55.5; p<0.0001), but Epworth sleepiness scale scores did not differ between conditions (all p values >0.56). CPAP use with heated humidity (5.52+/-2.1 h/night) was greater than CPAP use without humidity (4.93+/-2.2 h/night; p = 0.008). Compliance differences were not observed between CPAP use with cold passover humidity and CPAP use without humidity. Patients were more satisfied with CPAP when it was used with heated or cold passover humidity (p< or =0.05). However, only heated humidity resulted in feeling more refreshed on awakening (p<0.05). No significant differences were observed among the three groups on the global adverse side effect score (F2,37 = 2.5; p = 0.09). Specific side effects such as dry mouth or throat and dry nose were reported less frequently when CPAP was used with heated humidity compared to CPAP use without humidity (p<0.001).

CONCLUSIONS

Compliance with CPAP is enhanced when heated humidification is employed. This is likely due to a reduction in side effects associated with upper airway symptoms and a more refreshed feeling upon awakening. Compliance gains may be realized sooner if patients are started with heated humidity at CPAP initiation.

Positive pressure therapy

Positive airway pressure in the treatment of obstructive sleep-disordered breathing (OSDB) is reviewed. Continuous positive airway pressure (CPAP), bilevel positive airway pressure, and variable (auto-CPAP) pressure, their mechanisms of action, benefits, and complications are examined. A perspective on the future of positive airway pressure therapy for OSDB is provided.