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.     

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.     

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.     

Higher effective oronasal versus nasal continuous positive airway pressure in obstructive sleep apnea: Effect of mandibular stabilization

BACKGROUND:

In some individuals with obstructive sleep apnea (OSA), oronasal continuous positive airway pressure (CPAP) leads to poorer OSA correction than nasal CPAP. The authors hypothesized that this results from posterior mandibular displacement caused by the oronasal mask.

OBJECTIVE:

To test this hypothesis using a mandibular advancement device (MAD) for mandibular stabilization.

METHODS:

Subjects whose OSA was not adequately corrected by oronasal CPAP at pressures for which nasal CPAP was effective were identified. These subjects underwent polysomnography (PSG) CPAP titration with each nasal and oronasal mask consecutively, with esophageal pressure and leak monitoring, to obtain the effective pressure (Peff) of CPAP for correcting obstructive events with each mask (maximum 20 cmH₂O). PSG titration was repeated using a MAD in the neutral position. Cephalometry was performed.

RESULTS:

Six subjects with mean (± SD) nasal Peff 10.4±3.0 cmH₂O were studied. Oronasal Peff was greater than nasal Peff in all subjects, with obstructive events persisting at 20 cmH₂O by oronasal mask in four cases. This was not due to excessive leak. With the MAD, oronasal Peff was reduced in three subjects, and Peff <20 cmH₂O could be obtained in two of the four subjects with Peff >20 cmH₂O by oronasal mask alone. Subjects’ cephalometric variables were similar to published norms.

CONCLUSION:

In subjects with OSA with higher oronasal than nasal Peff, this is partially explained by posterior mandibular displacement caused by the oronasal mask. Combination treatment with oronasal mask and MAD may be useful in some individuals if a nasal mask is not tolerated.     

Excessive daytime sleepiness among rural residents in Saskatchewan

BACKGROUND:

Obstructive sleep apnea (OSA) is a common diagnosis in clinical practice. Excessive daytime sleepiness may be a warning for possible OSA.

OBJECTIVES:

To assess the prevalence of excessive daytime sleepiness as measured by the Epworth Sleepiness Scale (ESS) in a rural community population; potential risk factors for OSA were also assessed.

METHODS:

In 2010, a baseline respiratory health questionnaire within the Saskatchewan Rural Health Study was mailed to 11,982 households in Saskatchewan. A total of 7597 adults within the 4624 (42%) respondent households completed the ESS questionnaire. Participants were categorized according to normal or high (>10) ESS scores. Data obtained included respiratory symptoms, doctor-diagnosed sleep apnea, snoring, hypertension, smoking and demographics. Body mass index was calculated. Multivariable logistic regression analysis examined associations between high ESS scores and possible risk factors. Generalized estimating equations accounted for the two-tiered sampling procedure of the study design.

RESULTS:

The mean age of respondents was 55.0 years and 49.2% were male. The prevalence of ESS>10 and ‘doctor diagnosed’ OSA were 15.9% and 6.0%, respectively. Approximately 23% of respondents reported loud snoring and 30% had a body mass index >30 kg/m². Of those with ‘doctor-diagnosed’ OSA, 37.7% reported ESS>10 (P<0.0001) and 47.7% reported loud snoring (P<0.0001). Risk of having an ESS>10 score increased with age, male sex, obesity, lower socioeconomic status, marriage, loud snoring and doctor-diagnosed sinus trouble.

CONCLUSIONS:

High levels of excessive daytime sleepiness in this particular rural population are common and men >55 years of age are at highest risk. Examination of reasons for residual sleepiness and snoring in persons with and without sleep apnea is warranted.     

Characterization of primary symptoms leading to Chinese patients presenting at hospital with suspected obstructive sleep apnea

Objectives

We identified the primary symptoms leading to Chinese patients presenting at hospital with suspected obstructive sleep apnea (OSA) and studied the prevalence and characteristics of OSA in confirmed cases.

Methods

We collected data on 350 consecutive patients (302 males and 43±11 years old) with suspected OSA who underwent overnight polysomnography (PSG).

Results

Among all patients, rankings of primary symptoms that led to the patients presenting at hospital for PSG were observed apnea (33%), snoring alone (29%), choking/gasping (13%), daytime sleepiness (5%) and other (20%). For severe OSA, prevalence rate was 61%, apnea hypopnea index (AHI) was 64±18, age was 44±10 years old, body mass index (BMI) was 28±3.5 kg/m², and hypertension rate was 28%.

Conclusions

Self-awareness of symptoms led a majority of the patients to present at hospital in China. Compared to currently available case series studies, our results suggest that OSA patients in East Asian countries are characterized by higher prevalence and more severe apnea, younger age, poorer sleep quality, but less obesity and less comorbidity with hypertension, relative to countries in North America, South America and Europe.     

Long‐term use of continuous positive airway pressure therapy in coronary artery disease patients with nonsleepy obstructive sleep apnea

Background

Excessive daytime sleepiness is a frequent symptom of obstructive sleep apnea (OSA) and has been proposed as a motivator for adherence to continuous positive airway pressure (CPAP) therapy. However, excessive daytime sleepiness is absent in many patients with coronary artery disease (CAD) and concomitant OSA. We evaluated long‐term use of CPAP and predictors of CPAP use in nonsleepy and sleepy OSA patients from a CAD cohort.

Hypothesis

Long‐term CPAP use is lower in CAD patients with nonsleepy OSA vs sleepy OSA.

Methods

Nonsleepy (Epworth Sleepiness Scale [ESS] score < 10) OSA patients randomized to CPAP (n = 122) and sleepy (ESS ≥10) OSA patients offered CPAP (n = 155) in the RICCADSA trial in Sweden were included in this substudy. The median follow‐up was 4.8 years for the main trial, with a predefined minimum follow‐up of 2 years.

Results

The probability of remaining on CPAP at 2 years was 60% in nonsleepy patients and 77% in sleepy patients. Multivariate analyses indicated that age and hours of CPAP use per night at 1 month were independently associated with long‐term CPAP use in nonsleepy patients. In the sleepy phenotype, body mass index, acute myocardial infarction at baseline, and hours of CPAP use per night at 1 month were predictors of long‐term CPAP use.

Conclusions

Long‐term use of CPAP is likely to be challenging for CAD patients with nonsleepy OSA. Early CPAP use is an important predictor of continued long‐term use of CPAP, so optimizing patients' initial experience with CPAP could promote adherence.

     

A pathway underlying the impact of CPAP adherence on intimate relationship with bed partner in men with obstructive sleep apnea

Purpose

Our aim was to determine the pathway underlying the effects of continuous positive airway pressure (CPAP) adherence on intimate relationship with bed partner in men with obstructive sleep apnea (OSA). We hypothesized that CPAP with good adherence affected the intimate relationship with bed partner directly and indirectly, and it was mediated through daytime sleepiness and activity level in men with OSA.

Methods

Data were obtained from an education program for enhancing CPAP adherence. Men who were newly diagnosed of OSA and CPAP therapy naïve were recruited in a tertiary teaching hospital.

Results

Self-reported quality of life [Functional Outcomes of Sleep Questionnaire], daytime sleepiness [Epworth Sleepiness Scale (ESS)], and negative emotion symptoms [depression, anxiety, stress scale] were assessed before and after CPAP treatment at 1-year assessment. Seventy-three men were included in the data analysis, with a mean?±?SD age of 52?±?10 years, body mass index of 29.0?±?5.2 kg/m², ESS of 9.5?±?5.6, and median [interquartile range(IR)] apnea and hypopnea index of 31 (21, 56) events/h. The median (IR) CPAP daily usage was 4.3(0, 6.1)?h/day. From the path analysis, CPAP therapy was shown to improve intimate relationship directly (ß?=?0.185) and indirectly (ß?=?0.050) by reducing daytime sleepiness and increasing activity level. However, negative emotion symptoms were not the mediators between CPAP adherence and the intimate relationship.

Conclusions

CPAP therapy with good adherence is related directly and indirectly to a better intimate relationship with bed partner in men with OSA. It was possibly attributed to reduced daytime sleepiness and increased activity level.

     

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

BACKGROUND:

Obstructive sleep apnea (OSA) may contribute to the pathogenesis of congestive heart failure (CHF). Nocturnal continuous positive airway pressure (CPAP) therapy can alleviate OSA and may have a role in the treatment of CHF patients.

OBJECTIVES:

To investigate the acute and chronic effects of CPAP therapy on left ventricular systolic function, diastolic function and filling pressures in CHF patients with OSA.

METHODS:

Twelve patients with stable CHF (New York Heart Association II or III, radionuclide ejection fraction lower than 40%) underwent overnight polysomnography to detect OSA. In patients with OSA (n=7), echocardiography was performed at baseline (awake, before and during acute CPAP administration) and after 6.9±3.3 weeks of nocturnal CPAP therapy. Patients without OSA (n=5) did not receive CPAP therapy, but underwent a baseline and follow-up echocardiogram.

RESULTS:

In CHF patients with OSA, acute CPAP administration resulted in a decrease in stroke volume (44±15 mL versus 50±14 mL, P=0.002) and left ventricular ejection fraction ([LVEF] 34.8±5.0% versus 38.4±3.3%, P=0.006) compared with baseline, but no change in diastolic function or filling pressures (peak early diastolic mitral annular velocity [Ea]: 6.0±1.6 cm/s versus 6.3±1.6 cm/s, P not significant; peak early filling velocity to peak late filling velocity [E/A] ratio: 1.05±0.74 versus 1.00±0.67, P not significant; E/Ea ratio: 10.9±4.1 versus 11.3±4.1, P not significant). In contrast, chronic CPAP therapy resulted in a trend to an increase in stroke volume (59±19 mL versus 50±14 mL, P=0.07) and a significant increase in LVEF (43.4±4.8% versus 38.4±3.3%, P=0.01) compared with baseline, but no change in diastolic function or filling pressures (Ea: 6.2±1.2 cm/s versus 6.3±1.6 cm/s, P not significant; E/A ratio: 1.13±0.61 versus 1.00±0.67, P not significant; E/Ea ratio: 12.1±2.7 versus 11.3±4.1, P not significant). There was no change in left ventricular systolic function, diastolic function or filling pressures at follow-up in CHF patients without OSA.

CONCLUSIONS:

Acute CPAP administration decreased stroke volume and LVEF in stable CHF patients with OSA. In contrast, chronic CPAP therapy for seven weeks improved left ventricular systolic function, but did not affect diastolic function or filling pressures. The potential clinical implications of the discrepant effects of CPAP therapy on left ventricular systolic and diastolic function in CHF patients with OSA warrant further study.     

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.     

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.     

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.     

Prevalence of high Epworth Sleepiness Scale scores in a rural population

BACKGROUND:

Increased daytime sleepiness is an important symptom of obstructive sleep apnea (OSA). OSA is frequently underdiagnosed, and the Epworth Sleepiness Scale (ESS) can be a useful tool in alerting physicians to a potential problem involving OSA.

OBJECTIVE:

To measure the prevalence and determinants of daytime sleepiness measured using the ESS in a rural community population.

METHODS:

A community survey was conducted to examine the risk factors associated with ESS in a rural population in 154 households comprising 283 adults. Questionnaire information was obtained regarding physical factors, social factors, general medical history, family medical history, ESS score, and self-reported height and weight. Multivariable binary logistic regression analysis based on the generalized estimating equations approach to account for clustering within households was used to predict the relationship between a binary ESS score outcome (normal or abnormal) and a set of explanatory variables.

RESULTS:

The population included 140 men (49.5%) and 143 women (50.5%) with an age range of 18 to 97 years (mean [± SD] 52.0±14.9 years). The data showed that 79.2% of the study participants had an ESS score in the normal range (0 to 10) and 20.8% had an ESS score >10, which is considered to be abnormal or high sleepiness. Multivariable regression analysis revealed that obesity was significantly associated with an abnormal or high sleepiness score on the ESS (OR 3.40 [95% CI 1.31 to 8.80).

CONCLUSION:

High levels of sleepiness in this population were common. Obesity was an important risk factor for high ESS score.     

Pharmacologic approaches for the management of symptoms and cardiovascular consequences of obstructive sleep apnea in adults

Introduction

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxemia, arousals from sleep, and daytime sleepiness. Accumulating evidence indicates that hypoxemia and sleep disruption contribute to the development of cardiovascular abnormalities in OSA. OSA is effectively treated with continuous positive airway pressure (CPAP) therapy that splints open the airway during sleep. Studies have shown that CPAP therapy improves daytime sleepiness and attenuates cardiovascular abnormalities in patients with OSA. However, not all patients with OSA tolerate or adhere to CPAP therapy. Even patients who regularly use CPAP therapy may have a few hours each night exposed to the negative effects of untreated OSA. As a result, complementary pharmacologic therapies that can be used with CPAP therapy have the potential to reduce symptoms and consequences of OSA.

Discussion

The wake-promoting medications modafinil and armodafinil effectively improve residual sleepiness in patients treated with CPAP therapy. Although results are equivocal so far, modafinil and armodafinil may also improve quality of life and global clinical condition in patients with OSA and residual sleepiness treated with CPAP therapy. Pharmacologic therapies also have the potential to be used with CPAP therapy to minimize cardiovascular perturbations and risk of cardiovascular disease. Preliminary studies suggest that inhibition of the enzyme xanthine oxidase and inhibition of sympathetic nervous system overactivity may have therapeutic potential to reduce cardiovascular harm in patients with OSA.

Conclusion

Future studies of pharmacologic therapies to reduce symptoms and cardiovascular consequences of OSA should be increasingly performed as our understanding of the mechanisms mediating the adverse effects of OSA continues to evolve.     

Self-efficacy contributes to individual differences in subjective improvements using CPAP

Purpose  

Continuous positive airway pressure (CPAP) improves depressive symptoms and daytime sleepiness in patients with obstructive sleep apnea (OSA). However, there is variability in response to CPAP. This study examined individual differences in the daily associations between CPAP use and improvements in affect and sleepiness patients beginning CPAP.     

Pulse Oximeter Oxygen Saturation in Prediction of Arterial Oxygen Saturation in Liver Transplant Candidates

Background:

Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.

Objectives:

The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.

Patients and Methods:

Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO₂) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO₂) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.

Results:

Roc-derived SpO₂ threshold of ≤ 94% can predict hypoxemia (PaO₂ < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO₂ threshold of ≤ 97% and detection of hypoxemia (PaO₂ < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.

Conclusions:

Provided that SpO₂ is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.     

Association Between the Severity of Nocturnal Hypoxia in Obstructive Sleep Apnea and Non-Alcoholic Fatty Liver Damage

Background:

Obstructive sleep apnea (OSA) is a major disease that can cause significant mortality and morbidity. Chronic intermittent hypoxia is a potential causal factor in the progression from fatty liver to nonalcoholic steatohepatitis.

Objectives:

This study evaluated the association between the degree of liver steatosis and severity of nocturnal hypoxia.

Patients and Methods:

In this study, between December 2011 and December 2013, patients with ultrasound-diagnosed NAFLD evaluated by standart polysomnography were subsequentally recorded. Patients with alcohol use, viral hepatitis and other chronic liver diseases were excluded. We analyzed polysomnographic parameters, steatosis level and severity of obstructive sleep apnea (OSA) in consideration of body mass index (BMI), biochemical tests and ultrasonographic liver data of 137 subjects. Patients with sleep apnea and AHI scores of < 5, 5 - 14, 15 - 29 and ≥30 are categorized as control, mild, moderate and severe, respectively.

Results:

One hundred and thirty-seven patients (76 women, 61 men) with a mean age of 55.75 ± 10.13 years who underwent polysomnography were included in the study. Of 118 patients diagnosed with OSA, 19 (16.1%) had mild OSA, 39 (33.1%) moderate OSA and 60 (50.8%) severe OSA. Nineteen cases formed the control group. Apnea/hypopnea index and oxygen desaturation index (ODI) values were significantly higher in moderate and severe non-alcoholic fatty liver disease (NAFLD) compared to the non-NAFLD group. Mean nocturnal SpO₂ values were significantly lower in mild NAFLD and severe NAFLD compared to the non-NAFLD group. Lowest O₂ saturation (LaSO₂) was found low in mild, moderate and severe NAFLD compared to the non-NAFLD group in a statistically significant manner.

Conclusions:

We assessed polysomnographic parameters of AHI, ODI, LaSO₂ and mean nocturnal SpO₂ levels, which are especially important in the association between NAFLD and OSAS. We think that it is necessary to be attentive regarding NAFLD development and progression in patients with OSA whose nocturnal hypoxia is severe.     

Auto-titrating continuous positive airway pressure therapy in patients with chronic heart failure and obstructive sleep apnoea: a randomized placebo-controlled trial.

AIMS: Obstructive sleep apnoea (OSA) is highly prevalent in patients with chronic heart failure (CHF) and may contribute to CHF progression. We aimed to determine whether treatment of OSA with continuous positive airway pressure (CPAP) would improve subjective and objective measures of heart failure severity in patients with CHF and OSA. METHODS AND RESULTS: Twenty-six patients with stable symptomatic CHF and OSA were randomized to nocturnal auto-titrating CPAP or sham CPAP for 6 weeks each in crossover design. Study co-primary endpoints were changes in peak VO(2) and 6 min walk distance. Secondary endpoints were changes in left ventricular ejection fraction, VE/VCO(2) slope, plasma neurohormonal markers, and quality-of-life measures. Twenty-three patients completed the study protocol. Mean CPAP and sham CPAP usage were 3.5 +/- 2.5 and 3.3 +/- 2.2 h/night, respectively (P = 0.31). CPAP treatment was associated with improvements in daytime sleepiness (Epworth Sleepiness Score 7 +/- 4 vs. 8 +/- 5, P = 0.04) but not in other quality-of-life measures. There were no changes in other study endpoints. CONCLUSION: In patients with CHF and OSA, auto-titrating CPAP improves daytime sleepiness but not other subjective or objective measures of CHF severity. These data suggest that the potential therapeutic benefits of CPAP in CHF are achieved by alleviation of OSA rather than by improvement in cardiac function.