The association between obesity and outcomes in critically ill patients.

BACKGROUND: Obesity rates are increasing worldwide, particularly in North America. The impact of obesity on the outcome of critically ill patients is unclear. METHODS: A prospective observational cohort study of consecutive patients admitted to a tertiary critical care unit in Canada between January 10, 2008 and March 31, 2009 was conducted. Exclusion criteria were age <18 years, admission <24 h, planned cardiac surgery, pregnancy, significant ascites, unclosed surgical abdomen and brain death on admission. Height, weight and abdominal circumference were measured at the time of intensive care unit (ICU) admission. Coprimary end points were ICU mortality and a composite of ICU mortality, reintubation, ventilator-associated pneumonia, line sepsis and ICU readmission. Subjects were stratified as obese or nonobese, using two separate metrics: body mass index (BMI) ≥ 30 kg/m(2) and a novel measurement of 75th percentile for waist-to-height ratio (WHR). RESULTS: Among 449 subjects with a BMI ≥ 18.5 kg/m(2), both BMI and WHR were available for comparative analysis in 348 (77.5%). Neither measure of obesity was associated with the primary end points. BMI ≥ 3 0 kg/m(2) was associated with a lower odds of six-month mortality than the BMI <30 kg/m(2) group (adjusted OR 0.59 [95% CI 0.36 to 0.97]; P=0.04) but longer intubation times (adjusted RR 1.56 [95% CI 1.17 to 2.07]; P=0.003) and longer ICU length of stay (adjusted RR 1.67 [95% CI 1.21 to 2.31]; P=0.002). Conversely, measurement of 75th percentile for WHR was associated only with decreased ICU readmission (OR 0.23 [95% CI 0.07 to 0.79]; P=0.02). CONCLUSIONS: Obesity was not necessarily associated with worse outcomes in critically ill patients.

Increased nocturnal periodic limb movements in rheumatoid arthritis patients meeting questionnaire diagnostic criteria for restless legs syndrome.

BACKGROUND: Based on questionnaire criteria, the sensorimotor disorder restless legs syndrome (RLS) has been reported to have a higher prevalence in rheumatoid arthritis (RA) patients than in the general population. There has been some speculation that peripheral arthritic symptoms may allow false positive responses to questionnaire criteria. This study evaluates whether RA patients meeting RLS questionnaire criteria also have objective evidence of increased periodic limb movements (PLMs) characteristic of RLS. METHODS: Participants were recruited from RA clinic. Questionnaire data collected at study entry included: pain scores, rheumatoid arthritis disease activity index, Epworth sleepiness scale, Pittsburgh sleep quality index and RLS diagnostic criteria. Each participant was provided a PAM-RL actigraphic monitor, which attached to the ankle. This device was worn for two consecutive nights then returned for data download. Laboratory data including hemoglobin, iron studies, renal function and C-reactive protein levels were collected. RESULTS: Of the 57 participants, 23 met RLS diagnostic criteria. Those who met RLS criteria demonstrated higher mean frequency of nocturnal PLMs (19.63/hour; SD:21.13) than those who did not meet RLS criteria (11.13/hour; SD:12.10; p=0.033). There were no significant differences between groups in terms of patient characteristics, disease activity or duration measures. Patients meeting RLS criteria did have poorer sleep quality measures (p <0.001). CONCLUSIONS: RA patients who met RLS diagnostic criteria demonstrated higher frequencies of nocturnal PLMs than RA patients who did not meet criteria for RLS. This finding supports use of the RLS diagnostic criteria in helping to differentiate between RA arthritic symptoms and RLS.

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.

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.

Restless legs syndrome as a comorbidity in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a multisystem disease with a complex immunologic pathophysiology. Likewise, sleep disorders can involve a complicated interplay between the neurologic pathways, immune system, and respiratory system. Recent studies have shown an elevated prevalence of sleep abnormalities in connective tissue disorders compared to the general population. Restless legs syndrome (RLS) may be present in up to 30% of RA patients. These findings may be related to cytokine release and other immunomodulatory responses. TNF- α levels relate to sleep physiology and anti-TNF- α therapy may improve sleep patterns. Most of the patients with this disorder can distinguish their RLS sensations from their arthritic symptoms. RLS is a common comorbidity seen with RA, and prompt recognition and treatment can improve patient quality of life.

Relationship between the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale in a sleep laboratory referral population.

BACKGROUND: Sleep health questionnaires are often employed as a first assessment step for sleep pathology. The Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI) are two commonly employed questionnaire instruments. Aspects of sleep health may be measured differently depending on choice of instrument. OBJECTIVES: In a patient population at high risk for sleep disorders, referred for polysomnography (PSG), we evaluated the level of association between results from these two instruments. Questionnaire results were also compared with measured PSG parameters. METHODS: Records of patients undergoing overnight PSG in the sleep laboratory between February-June 2011 were retrospectively reviewed for eligibility. Inclusion criteria were met by 236 patients. PSQI and ESS scores, demographic information, and PSG data were extracted from each record for analysis. Four subgroups based on normal/abnormal values for ESS and PSQI were evaluated for between-group differences. RESULTS: Of 236 adult participants, 72.5% were male, the mean age was 52.9 years (13.9), mean body mass index (BMI) 34.4 kg/m(2) (8.3), mean ESS 9.0 (4.8; range: 0-22), PSQI mean 8.6 (4.2; range: 2-19). The Pearson correlation coefficient was r = 0.13 (P = 0.05) for association between ESS and PSQI. Participants with an abnormal ESS were more likely to have an abnormal PSQI score (odds ratio 1.9 [1.1-3.6]; P = 0.03). Those with an abnormal ESS had higher BMI (P = 0.008) and higher apnea-hypopnea indexes (AHI) (P = 0.05). Differences between the four subgroups were observed for BMI and sex proportions, but not for AHI. CONCLUSIONS: We observed limited association between these two commonly used questionnaire instruments, the ESS and the PSQI. These two questionnaires appear to evaluate different aspects of sleep. In terms of clinical application, for global assessment of patients with sleep problems, care should be taken to include instruments measuring different facets of sleep health.

Obstructive sleep apnoea in relation to rheumatic disease.

Sleep problems are common concerns in rheumatology patients and have been independently linked to increased pain perception and fatigue severity. Evidence supports an increased prevalence of primary sleep disorders, including sleep apnoea, in some rheumatic disease populations, particularly RA. Obstructive sleep apnoea is a significant public health concern and contributes to increased cardiovascular morbidity and mortality. Patients with obstructive sleep apnoea have also been found to have elevations in circulating acute-phase markers and pro-inflammatory cytokines. Co-existence of sleep apnoea in rheumatic disease patients may influence the severity of reported symptoms of pain and fatigue, accelerate the risk of cardiovascular events and possibly influence levels of circulating inflammatory markers and mediators. In this article we review the risk factors, prevalence and impact of sleep apnoea from a rheumatological perspective. Additionally, we recommend considering sleep apnoea screening in patients with rheumatic disease and, when appropriate, referral to a specialized sleep disorders clinic.

Do sleepy rheumatoid arthritis patients have a sleep disorder?

OBJECTIVE: Subjective reports of sleep dysfunction are common in people with rheumatoid arthritis (RA). Our objective was to determine whether excess sleepiness in RA is associated with polysomnographic (PSG) abnormalities. METHODS: Twelve RA participants with abnormal sleep scores were identified in clinic and age/gender matched to RA participants with normal Epworth Sleepiness Scale (ESS) scores. A total of 25 participants were recruited. All participants underwent overnight PSG studies with measurement of apnoea-hypopnoea indexes (AHI). Questionnaire instruments, including the ESS, Berlin questionnaire for sleep apnoea risk, visual analogue scale for fatigue, modified Health Assessment Questionnaire (mHAQ) and the Center for Epidemiologic Studies - Depression (CES-D) score, along with RA assessments, were reapplied on the PSG study night. RESULTS: Seven men and 18 women participated. Ten participants had abnormal ESS scores and 15 had normal ESS scores on the PSG night. PSG data revealed that 68% of patients had abnormal AHI (≥ 5). Abnormal ESS (> 10) had an 80% positive predictive value (PPV) for abnormal AHI; the negative predictive value (NPV) of normal ESS was 40%. By contrast, high-risk categorization for obstructive sleep apnoea (OSA) by the Berlin questionnaire had a PPV of 77.8%, and for low-risk status, an NPV of 37.5%. CONCLUSIONS: In the present study population, there was a high prevalence of abnormal AHI consistent with OSA. An abnormal ESS had high positive predictive value for an abnormal AHI.

Improved Sleep Efficiency after Anti-Tumor Necrosis Factor α Therapy in Rheumatoid Arthritis Patients.

BACKGROUND: Poor sleep health is increasingly recognized as contributing to decreased quality of life, increased morbidity/mortality and heightened pain perception. Our purpose in this study was to observe the effect on sleep parameters, specifically sleep efficiency, in rheumatoid arthritis (RA) patients treated with anti-tumor necrosis factor alpha (anti-TNF-α) therapy. METHODS: This was a prospective observational study of RA patients with hypersomnolence/poor sleep quality as defined by the Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI). Study patients underwent overnight polysomnograms and completed questionnaire instruments assessing sleep prior to starting anti-TNF-α therapy and again after being established on therapy. The questionnaire included the ESS, PSQI, the Berlin instrument for assessment of obstructive sleep apnea (OSA) risk, restless legs syndrome (RLS) diagnostic criteria, and measures of disease activity/impact. RESULTS: A total of 12 RA patients met inclusion criteria, of which 10 initiated anti-TNF-α therapy and underwent repeat polysomnograms and questionnaire studies approximately 2 months later. Polysomnographic criteria for OSA were met by 60% of patients. Following anti-TNF-α therapy initiation, significant improvements were observed by polysomnography (PSG) for sleep efficiency, increasing from 73.9% (SD 13.5) to 85.4% (SD 9.6) (p = 0.031), and 'awakening after sleep onset' time, decreasing from 84.1 minutes (SD 43.2) to 50.7 minutes (SD 36.5) (p = 0.048). Questionnaire instrument improvements were apparent in pain, fatigue, modified Health Assessment Questionnaire (mHAQ), and Rheumatoid Arthritis Disease Activity Index (RADAI) scores. CONCLUSIONS: Improved sleep efficiency and 'awakening after sleep onset' time were observed in RA patients treated with anti-TNF-α therapy.

Familial interstitial pulmonary fibrosis: a large family with atypical clinical features.

A large kindred of familial pulmonary fibrosis is reported. Six members from the first two generations of this particular kindred were described more than 40 years previously; six more individuals from the third and fourth generations have also been evaluated. The proband, now 23 years of age, has mild disease; the other 11 documented affected family members all died from their disease at an average age of 37 years (range 25 to 50 years). The pathology was that of usual interstitial pneumonia, as is typical in idiopathic pulmonary fibrosis. However, the initial radiographic pattern in many of these individuals was upper lobe and nodular and, along with the young age, was atypical for idiopathic pulmonary fibrosis. Several genetic abnormalities have been associated with familial pulmonary fibrosis. The present study examined the genes coding for surfactant protein-C, ATPbinding cassette protein A3 and telomerase, and found no abnormalities.

Hypersomnolence and sleep disorders in a rheumatic disease patient population.

OBJECTIVES: There is increasing awareness of the importance of sleep in health maintenance. Our primary objective was to evaluate prevalence of excess daytime sleepiness in a rheumatic disease patient population. Secondary objectives included evaluation of prevalence of abnormal sleep quality and primary sleep disorders. METHODS: Consecutive Rheumatology clinic patients were invited to participate in a self-administered questionnaire study. Included were measures for pain, fatigue, and global functioning, modified Health Assessment Questionnaire, Epworth Sleepiness Score (ESS), Pittsburgh Sleep Quality Index (PSQI), Berlin Score, diagnostic criteria for restless legs syndrome (RLS), Centre for Epidemiologic Studies Depression score (CES-D), stress scores, and the short form-36 quality of life instrument. RESULTS: Of 507 consecutive patients invited to participate, 423 agreed. Mean age was 52.1 years; 26% were male. Prevalence of excessive sleepiness (ESS >10) was 25.7%, abnormal sleep quality (PSQI >5) was 67.3%, high risk for obstructive sleep apnea Berlin scores were present in 35.2% and 24% of participants met criteria for RLS. Significantly worse pain, fatigue, global function, short form-36 summary scores, modified Health Assessment Questionnaire, depression, and stress scores were present in patients with higher ESS and PSQI scores. No significant differences in sleep assessment scores were observed between specific rheumatic disease groups. CONCLUSIONS: Our findings suggest a high prevalence of unrecognized hypersomnolence, poor sleep quality, and primary sleep disorders in rheumatology patients. We suggest evaluation of sleep health be incorporated into standard clinical assessments of all rheumatology patients. We would recommend this evaluation include the ESS and the criteria for RLS.

A questionnaire assessment of physical function in hyperlipidemic patients.

BACKGROUND: A spectrum of myopathic manifestations has been recognized as associated with lipid lowering drug therapy (LLT), but their effect on quality of life and physical functioning is uncertain. We conducted a prospective cohort study in which physical functioning was the dependent variable, in patients with and without exposure to LLT. METHODS: Consecutive patients attending a risk reduction clinic were invited to participate in a questionnaire study which included demographic data, muscular symptoms, the SF-36 Physical Function Score (PF), and the modified Health Assessment Questionnaire (mHAQ). Laboratory and co-morbidity data was recorded. RESULTS: Of 117 consecutive patients invited to participate, 112 consented. Of these, 81 were receiving statins and/or fibrates as LLT and 31 were participating in a non-pharmacologic therapeutic program (NPT) of diet and exercise therapy. The mean age for the total population was 56.7 years (20-78): the LLT group 58.6 and NPT group 51.9 years. Women comprised 53% of the LLT group and 58% of the NPT. No significant differences in baseline lipid profiles, CK level, BMI, waist measurement, gender, cigarette smoking, alcohol consumption, non-steroidal anti-inflammatory drugs or acetaminophen use, frequency of myalgias, SF-36 PF or mHAQ scores were observed between groups. On comparison of gender groups, we observed that men receiving LLT had significantly better SF- 36 PF (p = 0.037) than men on NPT. There were no differences in SF-36 PF or mHAQ scores between groups for females. CONCLUSION: We found no adverse effects of LLT on physical functioning or quality of life. Indeed, men treated with LLT had significantly better SF-36 PF scores than men treated non-pharmacologically.

Suspected carpal tunnel syndrome: Do nerve conduction study results and symptoms match?

OBJECTIVE: To evaluate the diagnostic utility of nerve conduction studies (NCSs) by examining a population with a high pretest probability of carpal tunnel syndrome (CTS), including bilaterally and unilaterally symptomatic patients. DESIGN: Comparison of the results of NCSs with the results of prospective, pre-NCS, self-administered questionnaires of patients with clinical diagnoses of CTS referred for confirmatory NCSs. SETTING: A tertiary care hospital neuro-electrophysiology laboratory. PARTICIPANTS: The study population consisted of 211 patients, 156 (73.9%) of whom were female. Population mean (range) age was 46.7 (21 to 88) years. Mean (range) symptom duration was 29.3 (1 to 300) months. MAIN OUTCOME MEASURES: Patient-reported symptom localization and NCS results. RESULTS: Results of NCSs were normal in 83 (39.3%) patients, were consistent with CTS in 121 (57.3%) patients, and suggested non-CTS abnormalities in 7 (3.3%) patients. Bilateral symptoms were reported by 139 (65.9%) patients, and isolated unilateral symptoms were reported by 72 (34.1%) patients. Those reporting bilateral symptoms had the highest agreement with NCS results at 38.8%. Unilateral NCS abnormalities were seen in 18.0% of those reporting bilateral hand symptoms. Discordant findings, either bilateral or opposite-side neuropathies, were seen in 25.6% of those reporting isolated right-sided symptoms, and in 55.2% of those reporting isolated left-sided symptoms. Based on these data the sensitivity of the NCS results was 49.1%, with a specificity of 62.5%. The positive predictive value was 86.4%, and the negative predictive value was 20.2%. Overall accuracy was 51.4%. Likelihood ratios were 1.3 with positive results, and 0.8 with negative results. CONCLUSION: In our study population NCS results did little to alter the pretest probability of CTS. Physicians using NCSs for verification of clinical diagnosis should be aware of potential limitations.

Digital gangrene associated with anticentromere antibodies: a case report.

INTRODUCTION: Anticentromere antibodies have been associated with peripheral vascular occlusive disease, most frequently accompanied by sclerodactyly in the context of a connective tissue disorder. We report a case of digital gangrene with no other clinical associations except positive anticentromere antibodies. CASE PRESENTATION: Our patient, a 53-year-old Caucasian woman, non-smoker, presented with progressive pain and blackening of the distal right third finger over the preceding five weeks. No sclerodactyly was evident. She was anticentromere antibody positive at greater than 100 U/mL. Angiography revealed diffuse distal vasculopathy in both upper extremities. Other investigations were unremarkable. CONCLUSIONS: It is rare for anticentromere antibody-associated digital necrosis to develop without concomitant sclerodactyly. However, this patient's case illustrates the need to consider an autoimmune contribution to the pathogenesis of digital ischemia even in the absence of a recognizable connective tissue disease.

Restless legs syndrome in a rheumatoid arthritis patient cohort.

OBJECTIVE: To use the 2003 International Restless Legs Syndrome Study Group (IRLSSG) diagnostic criteria and to evaluate restless legs syndrome (RLS) prevalence in a rheumatoid arthritis (RA) and osteoarthritis (OA) population. Further, we wished to evaluate physician awareness of this disorder by as reflected in prevalence of preexisting diagnoses of RLS in these populations. METHODS: This was a questionnaire study of Saskatchewan RA and OA patients enrolled in a longitudinal database study. A data collection instrument, including the 2003 IRLSSG criteria for RLS was distributed to the patients enrolled. RESULTS: Of the 193 respondents, 158 (81.9%) were women. The population consisted of 148 RA and 45 OA patients. RA patients were younger (mean age, 65.8 years) in comparison with those in the OA group (mean age, 72.8 years; P < 0.001). All criteria for RLS were met by 27.7% of RA patients and by 24.4% of OA patients. A previous diagnosis of RLS was reported by 2.6% of patients. CONCLUSIONS: A quarter of all our patients met the 2003 IRLSSG criteria, in both RA and OA groups; however, only 2.6% of study patients reported a previous diagnosis of RLS. As RLS can significantly affect quality of life, increased awareness with improvement in surveillance, recognition, and treatment would be beneficial to patient care. We advocate screening for symptoms of sleep disorders to be incorporated into the routine rheumatologic history for all patients with RA and OA.

Treatments for carpal tunnel syndrome: who does what, when ... and why?

OBJECTIVE: To determine how frequently treatments had been offered to patients with suspected diagnoses of carpal tunnel syndrome (CTS) who had been referred for confirmatory nerve conduction studies (NCSs) and to identify potential predictors of such treatment. A follow-up survey was conducted to determine the effect of NCS results on subsequent treatment. DESIGN: Self-administered survey questionnaire and follow-up telephone survey. SETTING: Royal University Hospital at the University of Saskatchewan in Saskatoon. PARTICIPANTS: Two hundred eleven patients with clinically suspected CTS who had been referred for confirmatory NCS. MAIN OUTCOME MEASURES: Results of NCSs, number of patients prescribed wrist splints or nonsteroidal anti-inflammatory drugs (NSAIDs) before and after NCSs, patient characteristics associated with being prescribed therapy, and reporting benefit of therapy. RESULTS: Nerve conduction studies confirmed CTS in 121 (57.3%) of the 211 study patients. Before NCSs, wrist splints and NSAIDs had been prescribed to 33.2% and 38.8% of patients, respectively. Splints and NSAIDs were reported to alleviate symptoms by 78.3% and 74% of patients, respectively, who received such treatments. No significant differences in age, sex, body mass index, symptom duration, symptom or function scores, or subsequent NCS results were noted between patients who were and were not prescribed these therapies or between those who did or did not report improvement in symptoms. Results of the follow-up survey indicated that the number of recommendations for splints and NSAIDs had doubled after NCSs were completed and that surgical intervention had been at least discussed in most cases. Treatment recommendations, including surgery, however, were not associated with identifiable patient factors, including patients' NCS results. CONCLUSION: Some patients were prescribed conservative treatments before NCSs. Following NCSs, prescriptions for wrist splints or NSAIDs approximately doubled. Interestingly, NCS results did not appear to influence subsequent therapeutic decision-making for either conservative treatment or surgical options. We think these findings suggest a lack of confidence in electrodiagnostic study results. It would be interesting to evaluate a larger population of primary care patients prospectively to examine further the use of NCSs in current clinical decision-making.

Mobile communication devices causing interference in invasive and noninvasive ventilators.

PURPOSE: The aim of this study was to assess if common mobile communication systems would cause significant interference on mechanical ventilation devices and at what distances would such interference occur. MATERIALS AND METHODS: We tested all the invasive and noninvasive ventilatory devices used within our region. This consisted of 2 adult mechanical ventilators, 1 portable ventilator, 2 pediatric ventilators, and 2 noninvasive positive pressure ventilatory devices. We operated the mobile devices from the 2 cellular communication systems (digital) and 1 2-way radio system used in our province at varying distances from the ventilators and looked at any interference they created. We tested the 2-way radio system, which had a fixed operation power output of 3.0 watts, the Global Systems for Mobile Communication cellular system, which had a maximum power output of 2.0 watts and the Time Division Multiple Access cellular system, which had a maximum power output of 0.2 watts on our ventilators. The ventilators were ventilating a plastic lung at fixed settings. The mobile communication devices were tested at varying distances starting at zero meter from the ventilator and in all operation modes. RESULTS: The 2-way radio caused the most interference on some of the ventilators, but the maximum distance of interference was 1.0 m. The Global Systems for Mobile Communication system caused significant interference only at 0 m and minor interference at 0.5 m on only 1 ventilator. The Time Division Multiple Access system caused no interference at all. Significant interference consisted of a dramatic rise and fluctuation of the respiratory rate, pressure, and positive end-expiratory pressure of the ventilators with no normalization when the mobile device was removed. CONCLUSIONS: From our experiment on our ventilators with the communication systems used in our province, we conclude that mobile communication devices such as cellular phones and 2-way radios are safe and cause no interference unless operated at very close distances of less than 1 meter.