The utility of the elbow sign in the diagnosis of OSA.

BACKGROUND: Multiple questionnaires have been used to predict the diagnosis of OSA. Such models typically have multiple questions requiring cumulative scoring for interpretation. We wanted to determine whether a simple two-part questionnaire has predictive value in the pretest clinical evaluation for OSA. METHODS: A questionnaire consisting of two questions--(1) Does your bed partner ever poke or elbow you because you are snoring? and (2) Does your bed partner ever poke or elbow you because you have stopped breathing?--was prospectively administered to patients evaluated in a sleep disorders clinic prior to undergoing polysomnography. Age, sex, BMI, and Epworth Sleepiness Scale data were collected. RESULTS: Among the 128 patients who had a polysomnogram, answering "yes" to being awakened for snoring increased the OR of an apnea-hypopnea index≥5/h 3.9 times compared with "no." Answering "yes" to being awakened for apneic spells was associated with an OR of 5.8 for an apnea-hypopnea index≥5/h compared with "no." These associations did not differ by sex, BMI, Epworth Sleepiness Scale or answering "yes" to the other question. Subjects>50 years old with OSA were less likely to report a positive elbow sign and had a significantly lower OR for being awakened for apneic spells than those<50 years old. The sensitivity and specificity of being awakened for apneic spells was 65% and 76%, respectively, with a positive predictive value of 90%. Subgroup analysis revealed that in men with a BMI>31 a positive elbow sign had a specificity of 96.6% for a diagnosis of OSA. CONCLUSIONS: Among patients referred to a sleep disorders clinic, a positive response to being elbowed/poked for apneic spells significantly improves the pretest prediction of OSA.

Inter-observer reliability of candidate predictive morphometric measurements for women with suspected obstructive sleep apnea.

OBJECTIVE: Obstructive sleep apnea (OSA) is increasingly recognized as a public health concern. Definitive diagnosis is by overnight polysomnographic (PSG) examination. Identification of clinical predictors would be beneficial in helping prioritize high-risk patients for assessment. Practical application of morphometric predictive variables would require a high level of reproducibility in a clinical setting. In this study, our objective was to evaluate reliability between observers in measurements of candidate morphometric parameters in women. DESIGN AND METHODS: This was a prospective study of 71 women who had been referred for PSG with suspected OSA. Selected morphometric parameters were measured independently in the sleep laboratory by two trained sleep physicians. RESULTS: Neck circumference and truncal measurements for lower costal, midabdominal, and hip circumferences had higher reliability coefficients (intraclass correlation coefficients [ICC] of 0.78, 0.95, 0.95, and 0.81) than the smaller dimension measurements, including cricomental distance or retrognathia (ICC of 0.04 and 0.17). Of the women participating in this study, 50 of 71 had apnea-hypopnea indexes (AHI) ≥ 5. Body mass index (BMI), neck circumference, lower costal girth, midabdominal girth, and hip girth were all significantly higher (p < 0.001-0.004) in women with AHI ≥ 5. CONCLUSIONS: There was wide variation in inter-observer reliability for different physical dimensions. We propose that any clinical morphologic measurement employed in predictive modeling should be reliably reproducible in clinical setting conditions. Our findings support the use of several truncal measures, BMI, and neck circumference as predictive measures in women undergoing evaluation for OSA.

An empirical continuous positive airway pressure trial for suspected obstructive sleep apnea.

BACKGROUND: Standard practice in obstructive sleep apnea (OSA) management requires that a positive diagnostic, overnight polysomnography (PSG) test be obtained before initiating treatment. However, long waiting times due to lack of access to PSG testing facilities may delay the initiation of definitive treatment for OSA. OBJECTIVES: To evaluate the response of patients who had a high clinical suspicion for OSA and who were waiting for a PSG test to an empirical continuous positive airway pressure (CPAP) trial. METHODS: A retrospective study of all patients who had been offered empirical CPAP therapy for suspected OSA was conducted. After outpatient assessment, 183 patients with a high pretest probability of having OSA began empirical CPAP testing using an arbitrary CPAP pressure. The presence of OSA, the accuracy of empirical CPAP pressure prescription, the adherence to empirical CPAP and the improvement in daytime somnolence were evaluated at the time of PSG. RESULTS: Of 183 patients on a CPAP trial, 91% had OSA, which was at least moderate (more than 15 apneas and hypopneas per hour of sleep) in 75% of the patients. Eighty per cent of the patients had significant daytime somnolence (Epworth Sleepiness Scale [ESS] greater than 10, mean +/- SD ESS 14+/-5), which improved with CPAP (ESS 9.0+/-5, P<0.01). In 40% of the patients, the arbitrary CPAP pressure was lower than that determined by manual titration. Adherence to a trial of CPAP (longer than 2 h/night) predicted OSA with a sensitivity of 82% and a specificity of 41%; the positive and negative predictive values were 92% and 22%, respectively. CONCLUSIONS: At the time of PSG testing, OSA was present in 91% of the patients who had received empirical CPAP. An empirical CPAP provided satisfactory interim treatment for excessive somnolence, despite the fact that the CPAP pressure was suboptimal in 40% of the patients.

The effects of helium-hyperoxia on 6-min walking distance in COPD: a randomized, controlled trial.

BACKGROUND: We hypothesized that breathing helium-hyperoxia (HeO2) would significantly improve 6-min walking test (6MWT) distance in COPD subjects. METHODS: This was a blinded, randomized crossover study. At visit 1, we assessed pulmonary function, exercise capacity, and 6MWT distance. Visits 2 and 3 consisted of four 6MWTs in which the following different inspired gases were used: room air (RA) by mask; 100% O2 by mask (mask O2); 100% O2 by nasal prongs (nasal O2); and 70% He/30% O2 by mask (HeO2). Walking distance, shortness of breath, leg fatigue, O2 saturation, and heart rate (HR) were assessed. RESULTS: Sixteen COPD subjects participated (mean FEV(1)/FVC ratio [+/- SD], 48 +/- 8%; mean FEV1, 55 +/- 13% predicted). Subjects walked farther when breathing HeO2 (564 m) compared to RA (497 m; p < 0.001), mask O2 (520 m; p < 0.001), or nasal O2 (528 m; p < 0.001). Despite the increased distance walked while breathing HeO2, there was no increase in shortness of breath or leg fatigue. There was desaturation when breathing RA (8%; p < 0.001) and nasal O2 (5%; p < 0.001), which was reduced when breathing HeO2 (3%; difference not significant) and mask O(2) (0%; difference not significant). There were no significant differences in HR in the four 6MWTs. CONCLUSIONS: The use of HeO2 increased 6MWT distance in COPD subjects more than either mask O2 or nasal O2 compared to RA. The increased walking distance was not associated with increased shortness of breath or leg fatigue. The results suggest that clinical benefit would be obtained by administering HeO2 during exercise, which may have significant clinical implications for the management of COPD patients.

The effect of neonatal bacille Calmette-Guérin vaccination on purified protein derivative skin test results in Canadian aboriginal children.

BACKGROUND: The effect that neonatal bacille Calmette-Guérin (BCG) vaccination has on tuberculin skin test (TST) results is not well evaluated in preschool children. METHODS: This was a retrospective cohort study of TST results in aboriginal children in Saskatchewan reserve communities. Records from the centralized provincial tuberculosis program were searched for aboriginal children aged 0 to 4 years during the time period 1991 to 1999. Only the first TST result reported as part of infant and preschool screening programs was considered. Children with active tuberculosis and those evaluated as part of a contact-tracing program were excluded. The BCG-vaccinated and unvaccinated groups were compared using wheal size cut points of 5 mm, 10 mm, and 15 mm. RESULTS: Data from 1,086 children with neonatal BCG vaccination and 1,867 unvaccinated children were analyzed. The rate of TST reactions was higher in vaccinated children at all ages, using a cut point of 5 mm. The rate of TST reactions was no different in vaccinated children >or= 1 year old when using a cut point of 15 mm. When using a cut point of 10 mm, the rate of TST reactions was higher at age 1 year but not different at age 4 years in the vaccinated children. CONCLUSION: The rate of TST reactions in preschool aboriginal children living on a reserve who have received neonatal BCG vaccination is affected by the cut point and age. The BCG vaccination status and age should therefore be considered when interpreting TST reactivity in the clinical assessment of aboriginal children participating in a tuberculosis control program.

The effect of ipratropium nasal spray on bronchial methacholine challenge.

PURPOSES: To determine the effect ipratropium bromide nasal spray has on methacholine challenge testing for airway hyperresponsiveness. MATERIALS AND METHODS: Ten subjects with known airway hyperresponsiveness to methacholine who had been clinically stable in the preceding 2 months participated in a randomized, double-blind, placebo-controlled, crossover study. Methacholine challenge testing was conducted on successive days: day 1 after pretreatment with aqueous 0.03% nasal ipratropium, and day 2 with normal saline solution placebo. RESULTS: The provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) was higher after nasal ipratropium than after saline solution placebo (2.1 mg/mL vs 1.6 mg/mL, p = 0.02). This difference is equal to approximately one-half concentration difference, probably within the limits of reproducibility of the test. CONCLUSIONS: Pretreatment with nasal ipratropium results in a small increase in PC20. Although this difference achieves statistical significance, it is probably not clinically significant.

The use of noninvasive ventilation in acute respiratory failure at a tertiary care center.

OBJECTIVE: Financial constraints and bed limitations frequently prevent admission of ill patients to a critical care setting. We surveyed the use of treatment with noninvasive ventilation (NIV) in clinical practice by physicians in a tertiary care, university-based teaching hospital and compared our findings with published recommendations for the use of NIV. METHODS: Data were collected prospectively on all patients with acute respiratory failure (ARF) for whom NIV was ordered over a 5-month period. The respiratory therapy department was responsible for administering NIV on written order by a physician. The respiratory therapist completed a survey form with patient tracking data for each initiation of NIV. The investigators then surveyed the clinical chart for clinical data. RESULTS: NIV was utilized for the treatment of ARF on 75 occasions during the 5-month period. Fourteen patients (18%) received NIV for a COPD exacerbation, and 61 patients (82%) received it for respiratory failure of other etiologies. NIV was initiated in the emergency department in 32% of patients, in a critical care setting in 27% of patients, in a ward observation unit in 23% of patients, and on a general medical or surgical ward in 18% of patients. Arterial blood gases (ABGs) were measured on 68 occasions prior to the initiation of NIV, and 51 patients had an ABG measurement within the first 6 h of treatment. The mean pH at baseline was 7.29, and 33% of patients had a baseline pH of < 7.25. Seven patients required endotracheal intubation (ETI) [13%], and there were 18 deaths (24%) with patients having do-not-resuscitate orders, accounting for 12 deaths. CONCLUSION: NIV is commonly used outside of a critical care setting. Our outcomes of ETI and death were similar to those cited in the literature despite less aggressive monitoring of these patients.

The effects of an anti-CD11a mAb, efalizumab, on allergen-induced airway responses and airway inflammation in subjects with atopic asthma.

BACKGROUND: Efalizumab is a humanized IgG(1) mAb against the lymphocyte function antigen-1 (LFA-1) alpha chain, CD11a. Blocking of LFA-1/intercellular adhesion molecule interactions could inhibit asthmatic inflammation by blocking adhesion and activation of LFA-1-positive leukocytes. OBJECTIVE: A randomized, double-blinded, placebo-controlled, parallel group, multicenter study investigated the effects of efalizumab on allergen-induced airway responsiveness and airway inflammation. METHODS: Thirty-five nonsmoking subjects with mild allergic asthma were randomized to receive efalizumab (n = 24) or placebo (n = 11) in 8 weekly subcutaneous doses (0.7 mg/kg conditioning dose followed by 7 weekly doses of 2.0 mg/kg). Allergen challenges were performed at screening and after 4 and 8 weeks of treatment. Samples of sputum (n = 18 subjects) and blood (n = 35 subjects) were collected the day before challenges, and sputum was collected again at 7 and 24 hours after each challenge. Nonparametric tests were used to compare allergen-induced differences between efalizumab and placebo groups. RESULTS: Subjects receiving efalizumab developed headache (48%) and flu syndrome (28%) compared to subjects receiving placebo (0%). After 8 weeks of efalizumab, the maximum late percent fall in FEV(1) (late asthmatic response) was inhibited by 50%, but neither the late response nor the late area under the curve was statistically different than placebo (P =.098 and.062, respectively). Efalizumab had no effect on the maximum early percent fall in FEV(1) (early asthmatic response) or early area under the curve compared to placebo (P >.59). Efalizu-mab significantly reduced the postallergen increase in sputum EG2-positive cells and metachromatic cells (P <.05). No other comparisons were statistically different. CONCLUSIONS: Blocking of LFA-1/intercellular adhesion module interactions by efalizumab inhibits the development of allergen-induced cellular inflammatory responses measured in induced sputum and might attenuate the late asthmatic response. Larger studies are needed to confirm this.

Formoterol thrice weekly does not result in the development of tolerance to bronchoprotection.

BACKGROUND: Loss of bronchoprotection routinely follows regular treatment with beta2-agonists. There are no data on the effects on bronchoprotection for thrice weekly use of a beta2-agonist. METHODS: A double-blind, randomized, placebo controlled crossover trial was conducted to investigate the effects of thrice weekly administration of 12 microg of formoterol versus placebo on bronchoprotection against methacholine. As an expected positive control, formoterol 12 microg once daily was also evaluated. RESULTS: There was no significant difference versus placebo in the bronchoprotective effects of 12 microg of formoterol administered on day 8, following daily treatment for seven days or treatment every other day (analysis of variance P=0.34). However, a nonsignificant trend towards lower concentration of methacholine that caused a 20% fall in forced expiratory volume in 1 s developed only following the daily formoterol dosing. CONCLUSIONS: Thrice weekly dosing does not result in the development of tolerance to bronchoprotection against the direct acting stimulus methacholine.

Long term survival in a patient with pulmonary lymphangioleiomyomatosis.

A patient with pulmonary lymphangioleiomyomatosis was diagnosed more than 22 years after the onset of symptoms by a thoracoscopic lung biopsy, after a high resolution computerized tomogram of the chest was highly suggestive of the disease. After nearly 30 years since the onset of her symptoms, the patient leads a relatively normal life with only mildly abnormal lung function and has minimal reduction in her exercise tolerance. There have been few reports of patients surviving for such a long time after the onset of this disease; the literature suggests that most patients die within 15 years of symptom onset.