Lidocaine toxicity in the setting of HeartMate II left ventricular assist device.

WHAT IS KNOWN AND OBJECTIVE: Lidocaine infused at 1-4 mg/min is an appropriate treatment modality for hemodynamically stable ventricular tachycardia (VT) with normal hepatic function. A case of acute lidocaine toxicity in the setting of left ventricular assist device (LVAD) is reported. CASE SUMMARY: A 71-year-old with a HeartMate II LVAD on chronic mexiletine and normal liver function presented with ventricular tachycardia requiring systemic lidocaine and subsequently developed altered mental status with tremors. A lidocaine level obtained within 24 hours of infusion initiation was 7.9 mcg/mL. WHAT IS NEW AND CONCLUSION: This case highlights the potential for marked deviation from published pharmacokinetic parameters for a narrow therapeutic window agent with concurrent LVAD.

Echocardiographic and electrocardiographic findings in patients with obesity hypoventilation syndrome.

BACKGROUND: Obesity is a risk factor for both sleep-related breathing disorders (SRBD), including obesity hypoventilation syndrome (OHS) and cardiovascular diseases (CVD). The development of CVD in patients with SRBD is usually attributed to the fact that most patients are obese in addition to conventional cardiovascular risk factors. AIMS: This study aims to measure the prevalence of certain CVD in patients with OHS in the Auckland region and highlight the importance of the effects of SRBD on the heart. METHODS: A dataset of all patients with a formal diagnosis of OHS that were under active follow up was compiled from Auckland District Health Board Sleep Disordered Breathing Service. Clinical notes were retrospectively reviewed for echocardiogram reports, blood pressure measurements and electrocardiograms. RESULTS: Forty-seven patients were included in the present study. The median age was 60 years, 24 were female (51%), 20 (42.5%) had diabetes, mean HbA1C was 53.5 mmol/mol, mean systolic blood pressure was 127 mmHg, mean body mass index was 49 kg/m(2) , mean forced expiratory volume in 1 s was 1.7 L, mean estimated glomerular filtration was 71 mL/min/1.73 m(2) and there was anti-hypertensive use in 31 (65.9%) patients. Thirty-three patients had poor quality echocardiography views (70.2%). Left ventricular systolic and diastolic function was impaired in 8 (25%) and 18 (60%) respectively. Right ventricular dysfunction and pulmonary hypertension was present in 19 (63.3%) and 13 (52%) respectively. Sixteen patients (34%) had recurrent atrial or ventricular arrhythmias. CONCLUSION: There appears to be a high prevalence of right ventricular impairment, pulmonary hypertension, left ventricle hypertrophy, diastolic dysfunction and arrhythmias in patients with OHS. These findings would appear to be higher than expected in obese patients without OHS. A larger prospective matched cohort study would be needed to confirm the clinical significance of these findings.

Differential susceptibility of invasive Haemophilus influenzae serotype a and serotype b to ampicillin and other commonly prescribed antibiotics.

UNLABELLED: Haemophilus influenzae serotype a (Hia) has become an important pathogen in the post-H. influenzae serotype b (Hib) vaccine era. Antibiotic resistance in H. influenzae is a global phenomenon, but few studies have looked at antibiotic resistance profiles with regard to serotype. Invasive Hia (n = 157), noninvasive Hia (n = 2) and invasive Hib (n = 42) collected over the last two decades from three Canadian Provinces were examined for resistance to several commonly prescribed antibiotics, and sequence types (STs) were determined by MLST. Only 1·9% of Hia showed antibiotic resistance, while 31% of Hib were resistant to one or more antibiotic. Resistance to ampicillin, sulfamethoxazole-trimethoprim, chloramphenicol and tetracycline was observed, with ß-lactamase-mediated ampicillin resistance being the most common. Nine STs were identified for Hia with 7 STs belonging to the same clonal complex. Ten STs were observed in Hib strains, and all of them belonged to a single clonal complex. A possible correlation between sequence type and ampicillin resistance was observed for Hib, while no correlations were observed for Hia. SIGNIFICANCE AND IMPACT OF THE STUDY: Despite H. influenzae serotype b (Hib) vaccine programs, invasive disease due to Hib still exists in Canada and is either second or third most common behind nontypeable and/or serotype a (Hia). Many previous studies on antibiotic resistance have focussed on respiratory isolates, and few have looked at resistance with regard to serotype. This study analysed antibiotic resistance in invasive Hia and Hib collected over 20 years from three provinces, and results found that significantly more Hib showed resistance compared to Hia. This provides a small snapshot of H. influenzae disease in Canada and highlights the importance to continually monitor antibiotic resistance profiles.

Pulmonary hypertension and breathlessness: is it a combination we can ignore?

On 5 May 2013 it was World Pulmonary Hypertension (PHT) Day marking three decades on from the first reported deaths in an epidemic because of toxic rapeseed (canola) oil. This epidemic provided the impetus to the first World Health Organization to set up a world symposia. World leaders of PHT met for the fifth time in Nice, France in February 2013. Although we wait the official proceedings, this meeting provides us opportunity to reflect on the current situation in Australia and New Zealand, and examine the implications for our two countries. PHT remains difficult to identify, delays in patient diagnosis persist, and breathlessness remains dominant in the diagnosis of all causes of PHT. This review examines some of the recent changes in diagnosis, our understanding of the emerging expanding epidemiology data and the patient's journeys through the healthcare system. We also review the current treatment options on monotherapy and in poly-pharmacy or combination therapy, along with the strategic management implications of the lack of funded combination therapy associated with prognosis.

Building a pulmonary vascular service: the 12-year experience and outcomes of the Auckland pulmonary arterial hypertension clinic.

BACKGROUND AND AIMS: Pulmonary arterial hypertension (PAH) is associated with significant morbidity and mortality. In New Zealand, access to PAH-specific pharmacotherapy has been restricted for economic reasons. Since 2009, access to medication has been provided by a Special Authority scheme that ensures equity of access for all patients. Management of patients with PAH in this environment poses unique challenges. This study describes outcomes of patients managed in the Auckland PAH clinic over a 12-year period. METHODS: The clinic database was interrogated. Patients were eligible for this study if they had PAH (World Health Organization (WHO) Class 1, 1' and 4) and had been managed in the clinic from the year 2000. RESULTS: One hundred and twenty-six patients (75% female, mean age at diagnosis 50) were included. Most had idiopathic PAH (37%) or PAH because of connective tissue disease (29%). At diagnosis, patients had advanced disease (median WHO Class III, 6-min walk distance 367 m and pulmonary vascular resistance of 10.6 Wood Units). Initial therapy was sildenafil in most cases. PAH-specific therapy was associated with improved WHO class and longer 6-min walk distance (P < 0.01 for both). Thirty per cent of patients were escalated to combination therapy. Survival was 91% at 1 year and 67% at 5 years. CONCLUSIONS: Despite historic difficulties with access to PAH-specific therapy, these data confirm benefits of therapy (primarily sildenafil as first-line treatment) for patients with PAH managed within the Auckland PAH clinic. Survival data are comparable with other reported cohorts.

The association between resting and mild-to-moderate exercise pulmonary artery pressure.

The mean pulmonary artery pressure (P(pa)) achieved on mild-to-moderate exercise is age related and its haemodynamic correlates remain to be documented in patients free of pulmonary hypertension (PH). Our retrospective study involved patients free of PH investigated in our centre for possible pulmonary vascular disease between January 1, 2007 and October 31, 2009 who underwent right heart catheterisation at rest and during supine exercise up to 60 W. The 38 out of 99 patients aged <50 yrs were included and a P(pa) of 30 mmHg was considered the upper limit of normal on exercise. The 24 subjects who developed P(pa)>30 mmHg on exercise had higher resting P(pa) (19±3 versus 15±4 mmHg) and indexed pulmonary vascular resistance (PVRi; 3.4±1.5 versus 2.2±1.1 WU·m(2); p<0.05) than the remaining 14 subjects. Resting P(pa) >15 mmHg predicted exercise P(pa) >30 mmHg with 88% sensitivity and 57% specificity. The eight patients with resting P(pa) 22-24 mmHg all had exercise P(pa) >30 mmHg. In subjects aged <50 yrs investigated for possible pulmonary vascular disease and free of PH, patients with mild-to-moderate exercise P(pa) >30 mmHg had higher resting PVRi and higher resting P(pa), although there was no resting P(pa) threshold value that could predict normal response on mild-to-moderate exercise. The clinical relevance of such findings deserves further long-term follow-up studies.

Progressive pulmonary hypertension post atrial septal defect device closure-early symptomatic improvement may not predict outcome.

BACKGROUND: For patients with an atrial septal defect and pulmonary hypertension it can be difficult to determine whether it is safe to intervene. With newer treatments for pulmonary hypertension and transcatheter techniques avoiding surgical stressors, it has been hoped that we can occlude previously inoperable defects safely. METHODS: We undertook a subgroup analysis of outcomes for patients with mean pulmonary artery pressure (PAp) ≥30mmHg from within our database of patients undergoing transcatheter ASD closure from 1997 to 2004. RESULTS: Data for 11 patients were reviewed. Mean age of the patients at intervention was 38 years (5-69 years). Eight patients have had symptomatic improvement with no evidence of progressive pulmonary hypertension. There was one death due to unrelated causes. Two patients have developed progressive pulmonary vascular disease with one death. CONCLUSIONS: Despite early symptomatic improvement, adverse outcomes may occur in patients with elevated pulmonary vascular resistance undergoing transcatheter ASD closure. Careful haemodynamic evaluation is vital. Modest elevation of pulmonary vascular resistance and the presence of left to right shunt (Qp:Qs>1.5:1) are reassuring.

A gene expression signature classifying telomerase and ALT immortalization reveals an hTERT regulatory network and suggests a mesenchymal stem cell origin for ALT.

Telomere length is maintained by two known mechanisms, the activation of telomerase or alternative lengthening of telomeres (ALT). The molecular mechanisms regulating the ALT phenotype are poorly understood and it is unknown how the decision of which pathway to activate is made at the cellular level. We have shown earlier that active repression of telomerase gene expression by chromatin remodelling of the promoters is one mechanism of regulation; however, other genes and signalling networks are likely to be required to regulate telomerase and maintain the ALT phenotype. Using gene expression profiling, we have uncovered a signature of 1305 genes to distinguish telomerase-positive and ALT cell lines. By combining this with the gene expression profiles of liposarcoma tissue samples, we refined this signature to 297 genes. A network analysis of known interactions between genes within this signature revealed a regulatory signalling network consistent with a model of human telomerase reverse transcriptase (hTERT) repression in ALT cell lines and liposarcomas. This network expands on our existing knowledge of hTERT regulation and provides a platform to understand differential regulation of hTERT in different tumour types and normal tissues. We also show evidence to suggest a novel mesenchymal stem cell origin for ALT immortalization in cell lines and mesenchymal tissues.

Reactive oxygen species modulate neuronal excitability in rat intrinsic cardiac ganglia.

Reactive oxygen species (ROS) are produced as by-products of oxidative metabolism and occur in the heart during ischemia and coronary artery reperfusion. The effects of ROS on the electrophysiological properties of intracardiac neurons were investigated in the intracardiac ganglion (ICG) plexus in situ and in dissociated neurons from neonatal and adult rat hearts using the whole-cell patch clamp recording configuration. Bath application of ROS donors, hydrogen peroxide (H(2)O(2)) and tert-butyl hydroperoxide (t-BHP) hyperpolarized, and increased the action potential duration of both neonatal and adult ICG neurons. This action was also recorded in ICG neurons in an adult in situ ganglion preparation. H(2)O(2) and t-BHP also inhibited voltage-gated calcium channel (VGCC) currents and shifted the current-voltage (I-V) relationship to more hyperpolarized potentials. In contrast, H(2)O(2) increased the amplitude of the delayed rectifier K(+) current in neonatal ICG neurons. In neonatal ICG neurons, bath application of either superoxide dismutase (SOD) or catalase, scavengers of ROS, prior to H(2)O(2) attenuated the hyperpolarizing shift but not the inhibition of VGCC by H(2)O(2). In contrast, in adult ICG neurons, application of SOD alone had no effect upon either VGCC current amplitude or the I-V relationship, whereas application of SOD prior to H(2)O(2) exposure abolished both the H(2)O(2)-mediated hyperpolarizing shift and inhibition. These data indicate that ROS alter depolarization-activated Ca(2+) and K(+) conductances which underlie neuronal excitability of ICG neurons. This affects action potential duration and therefore probably modifies autonomic control of the heart during ischemia/reperfusion.

Topical or oral ibuprofen for chronic knee pain in older people. The TOIB study.

OBJECTIVES: To determine whether GPs should advise their older patients with chronic knee pain to use topical or oral non-steroidal anti-inflammatory drugs (NSAIDs). DESIGN: An equivalence study was designed to compare the effect of advice to use preferentially oral or topical ibuprofen (an NSAID) on knee pain and disability, NSAID-related adverse effects and NHS/societal costs, using a randomised controlled trial (RCT) and a patient preference study (PPS). Reasons for patient preferences for topical or oral preparations, and attitudes to adverse effects, were explored in a qualitative study. SETTING: Twenty-six general practices in the UK. PARTICIPANTS: Participants comprised 585 people with knee pain, aged 50 years or over; 44% were male, mean age 64 years. The RCT had 282 participants: 144 in the oral group and 138 in the topical group. The PPS had 303 participants: 79 in the oral group and 224 in the topical group. INTERVENTIONS: Advice to use preferentially oral or topical NSAIDs for knee pain. OUTCOME MEASURES: The primary outcome measure was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcome measures were the Short Form with 36 Items (SF-36), perceived troublesomeness of knee pain, satisfaction with health status, major adverse effects (unplanned hospital admissions and deaths) and minor adverse events over 12 months. The health economic analysis measured the comparative cost per quality-adjusted life-year (QALY) from both an NHS and a societal perspective over 1 and 2 years. RESULTS: Changes in the global WOMAC score at 12-months were equivalent in both studies: topical - oral, RCT difference=2 [95% confidence interval (CI) -2 to 6], PPS difference=1 (95% CI -4 to 6). There were no differences in the secondary outcomes, except for a suggestion, in the RCT, that those in the topical group were more likely to have more severe overall pain and disability as measured by the chronic pain grade, and more likely to report changing treatment because of inadequate pain relief. There were no differences in the rate of major adverse effects but some differences in the number of minor ones. In the RCT, 17% and 10% in the oral and the topical group, respectively, had a defined respiratory adverse effect (95% CI of difference -17% to -2.0%); after 12 months, the change in serum creatinine was 3.7 mmol/l (95% CI 0.9 to 6.5) less favourable in the oral than in the topical group, and 11% of those in the oral group reported changing treatment because of adverse effects compared with 1% in the topical group (p=0.02). None of these differences were seen in the PPS. Oral NSAIDs cost the NHS 191 pounds and 72 pounds more per participant over 1 year in the RCT and PPS respectively. In the RCT the cost per QALY in the oral group, from an NHS perspective, was in the range 9000-12,000 pounds. In the PPS it was 2564 pounds over 1 year, but over 2 years the oral route was more cost-effective. Patient preference for medication type was affected by previous experience of medication (including adverse reactions), other illness, pain elsewhere, anecdotes, convenience, severity of pain and perceived degree of degeneration. Lack of understanding about knee pain and the action of medication led to increased tolerance of symptoms. Potentially important symptoms may inadvertently have been disregarded, increasing participants' risk of suffering a major adverse effect. CONCLUSIONS: Advice to use either oral or topical preparations has an equivalent effect on knee pain, but oral NSAIDs appear to produce more minor adverse effects than topical NSAIDs. Generally, these results support advising older people with knee pain to use topical rather than oral NSAIDS. However, for patients who prefer oral NSAID preparations rather than a topical NSAID, particularly those with more widespread or severe pain, the oral route is a reasonable treatment option, provided that patients are aware of the risks of potentially serious adverse effects from oral medication. Further research is needed into strategies to change prescribing behaviour and ensure that older patients are aware of the potential risks and benefits of using NSAIDs. Observational studies are needed to estimate rates of different predefined minor adverse effects associated with the use of oral NSAIDs in older people as are long-term studies of topical NSAIDs in those for whom oral NSAIDs are not appropriate.

Clinical audit: optimal positioning of endotracheal tubes in neonates.

BACKGROUND: The malposition of endotracheal tubes (ETTs) can be associated with endo-bronchial intubation or accidental extubation. A variety of methods have been reported for predicting insertional length (IL) including weight, nasal-tragus length (NTL) and sternal length (STL) measurements. In our unit no consistent predictor method was being used. AIM: To audit the proportion of endotracheal tubes that required a significant position change after oral intubation. Our standard set was that the endotracheal tube should be in a satisfactory position in > 80% of cases. If not met, practice would then be re-audited after a consistent predictor method had been implemented. METHODS: Data regarding changes in endotracheal tube position were collected. Significant position changes were defined as adjustments > 0.5 cm. RESULTS: Twenty two babies were included in the initial audit, and only 73% of endotracheal tubes had a satisfactory position. Thirty six babies were included in the re-audit and when the nasal-tragus length predictor was used, 94% of endotracheal tubes had a satisfactory position, meeting the standard. CONCLUSION: The nasal-tragus length predictor improved the accuracy of endotracheal tube positioning after oral intubation. It is a simple, fast, reproducible method and can be used in everyday practice to help avoid significant endotracheal tube malposition.

Prevalence of chronic renal failure in the diabetic population at the University Hospital of the West Indies.

The prevalence of chronic renal failure (CRF) in 460 patients with diabetes mellitus attending the diabetic outpatient clinic at the University Hospital of the West Indies in Jamaica was determined from a review of medical records. The prevalence of CRF was 10% (39/386) in the diabetic clinic population. Significant positive associations with CRF were found with male gender (20/98, 20% vs 19/287, 7%; odds ratio (OR), 3.24; p = 0.001); age 60 years and older (22/162; 14% vs 17/221, 8%; OR, 2.01; p = 0.04); fasting blood glucose concentrations exceeding 8.0 mmol/L (22/162, 13% vs 12/182, 7%; OR, 2.08; p = 0.05); the presence of significant proteinuria as a marker for outcome (13/39, 33% vs 48/346, 14%; OR, 3.60; p = 0.02) and peripheral vascular disease (6/20, 30% vs 139/386, 10%; OR, 4.75; p = 0.005). The prevalence of CRF did not differ significantly between patients with Type 1 and Type 2 diabetes mellitus. Also, the presence of CRF was not significantly associated with duration of diabetes mellitus, type of hypoglycaemic agents used, or history of hypertension. However, the presence of persistent proteinuria was significantly associated with duration of diabetes mellitus exceeding five years (46/255, 17% vs 11/149, 7%; OR, 2.52; p = 0.005) and a history of hypertension (41/235, 17% vs 20/198, 10%; OR, 1.88; p = 0.03) but not with age or gender. This study emphasizes the need to evaluate patients with diabetes mellitus for renal impairment so that intervention strategies may be adopted early to delay progression to endstage renal disease.

Prevalence of chronic renal failure in the diabetic population at the University Hospital of the West Indies

The prevalence of chronic renal failure (CRF) in 460 patients with diabetes mellitus attending the diabetic outpatient clinic at the University Hospital of the West Indies in Jamaica was determined from a review of medical records. The prevalence of CRF was 10 (39/386) in the diabetic clinic population. Significant positive associations with CRF were found with male gender (20/98, 20 vs 19/287, 7; odds ratio (OR), 3.24; p = 0.001); age 60 years and older (22/162; 14 vs 17/221, 8; OR, 2.01; p = 0.04); fasting blood glucose concentrations exceeding 8.0 mmol/L (22/162, 13 vs 12/182, 7; OR, 2.08; p = 0.05); the presence of significant proteinuria as a marker for outcome (13/39, 33 vs 48/346, 14; OR, 3.60; p = 0.02) and peripheral vascular disease (6/20, 30 vs 139/386, 10; OR, 4.75; p = 0.005). The prevalence of CRF did not differ significantly between patients with Type 1 and Type 2 diabetes mellitus. Also, the presence of CRF was not significantly associated with duration of diabetes mellitus, type of hypoglycaemic agents used, or history of hypertension. However, the presence of persistent proteinuria was significantly associated with duration of diabetes mellitus exceeding five years (46/255, 17 vs 11/149, 7; OR, 2.52; p = 0.005) and a history of hypertension (41/235, 17 vs 20/198, 10; OR, 1.88; p = 0.03) but not with age or gender. This study emphasizes the need to evaluate patients with diabetes mellitus for renal impairment so that intervention strategies may be adopted early to delay progression to endstage renal disease

UK Back pain Exercise And Manipulation (UK BEAM) trial--national randomised trial of physical treatments for back pain in primary care: objectives, design and interventions [ISRCTN32683578].

BACKGROUND: Low back pain has major health and social implications. Although there have been many randomised controlled trials of manipulation and exercise for the management of low back pain, the role of these two treatments in its routine management remains unclear. A previous trial comparing private chiropractic treatment with National Health Service (NHS) outpatient treatment, which found a benefit from chiropractic treatment, has been criticised because it did not take treatment location into account. There are data to suggest that general exercise programmes may have beneficial effects on low back pain. The UK Medical Research Council (MRC) has funded this major trial of physical treatments for back pain, based in primary care. It aims to establish if, when added to best care in general practice, a defined package of spinal manipulation and a defined programme of exercise classes (Back to Fitness) improve participant-assessed outcomes. Additionally the trial compares outcomes between participants receiving the spinal manipulation in NHS premises and in private premises. DESIGN: Randomised controlled trial using a 3 x 2 factorial design. METHODS: We sought to randomise 1350 participants with simple low back pain of at least one month's duration. These came from 14 locations across the UK, each with a cluster of 10-15 general practices that were members of the MRC General Practice Research Framework (GPRF). All practices were trained in the active management of low back pain. Participants were randomised to this form of general practice care only, or this general practice care plus manipulation, or this general practice care plus exercise, or this general practice care plus manipulation followed by exercise. Those randomised to manipulation were further randomised to receive treatment in either NHS or private premises. Follow up was by postal questionnaire one, three and 12 months after randomisation. The primary analysis will consider the main treatment effects before interactions between the two treatment packages. Economic analysis will estimate the cost per unit of health utility gained by adding either or both of the treatment packages to general practice care.

Ambulatory oxygen improves quality of life of COPD patients: a randomised controlled study.

It is unknown whether acute response to ambulatory oxygen (O2) predicts longer term improvement in health-related quality of life (HRQL) in chronic obstructive pulmonary disease (COPD) patients. The aims of this study were 1) to assess the short-term clinical impact, as determined by HRQL, of ambulatory O2 in a 12-week, double-blind, randomised crossover study of O2 (versus cylinder compressed air) of dyspnoeic but not chronically hypoxic COPD patients with exertional desaturation < or = 88% (n=41), and 2) to determine whether either baseline characteristics or acute response to O2 predicts short-term (12 weeks) response. Primary outcome measures were Chronic Respiratory Questionnaire (CRQ), Hospital Anxiety and Depression scale and the short form (SF)-36. Improvements were seen in all domains of the CRQ for cylinder O2 compared with cylinder air. Significant improvements were also noted in anxiety and depression and in certain domains of the SF-36. There were 28 (68%) acute responders to cylinder O2 (defined as increase in 6-min walk > or = 54 m or decrease in post-Borg dyspnoea > or = 1) and 23 (56%) short-term responders (defined as clinically significant improvement in CRQ). However, acute and short-term responses were not correlated with no predictors of short-term response identified. At study completion, 14 (41%) of acute or short-term responders did not want to continue therapy, with 11 citing poor acceptability or tolerability. Short-term ambulatory oxygen is associated with significant improvements in health-related quality of life. These benefits cannot be predicted by baseline characteristics or acute response. Despite acute or short-term response, a substantial proportion of patients declined ambulatory oxygen.

HRT and breast changes.

S K is a sensible, fit 53 year old with irritating menopausal symptoms who wants to discuss hormone replacement therapy (HRT). She has had a previous mammogram which described moderately dense breasts with only fair visibility for discrete lesions. More recently she had a screening mammogram at BreastScreen, and received a routine 'all clear' letter. You believe that HRT can relieve her symptoms.

Craniofacial form and obstructive sleep apnea in Polynesian and Caucasian men.

STUDY OBJECTIVES: This aim of this study was to determine the relative contributions of craniofacial form and anthropometric factors to obstructive sleep apnea (OSA) in two different racial groups, both markedly obese and with a similar mean respiratory disturbance index (RDI). DESIGN: A cross-sectional study of New Zealand Maori (Polynesian) and European (Caucasian) men with RDI> or =15, using lateral and postero-anterior cephalometric radiography. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. MEASUREMENTS AND RESULTS: Measurements of facial and cranial width, length and height, airway size, stature, weight, body mass index (BMI), neck circumference, RDI, and age were obtained. The Polynesian men had, on average, a greater neck circumference than the Caucasian men. There were no significant differences in age, weight, BMI or RDI between the two groups. The Polynesian men also had broader craniofacial skeletons, larger and more prognathic mandibles, greater neck extension, and some larger airway dimensions than the Caucasian men. In the Polynesian men, the width of the bony nasal aperture was positively associated with RDI, and mandibular prognathism was negatively associated with RDI. In contrast, in the Caucasian men only neck circumference was positively associated with RDI, while the retropalatal airway was negatively associated with RDI. CONCLUSIONS: The results indicate that OSA in these two racially distinct groups is due to different etiological factors. Small reductions in mandibular prognathism and a wider bony nasal aperture were major factors associated with OSA in Polynesians. On the other hand, in the Caucasian group OSA was associated with a larger neck circumference and a reduced retropalatal airway size.