Obstructive sleep apnoea predicted by the STOP-BANG questionnaire is not associated with higher rates of post-operative complications among a high-risk surgical cohort.

PURPOSE: The purpose of this study is to establish if obstructive sleep apnoea (OSA) predicted by the STOP-BANG questionnaire would be associated with higher rates of post-operative cardiac, respiratory or neurological complications among a selected high-risk population with established major comorbidities undergoing major surgery. We hypothesise that a cohort selected for major comorbidities will show a higher post-operative complication rate that may power any potential association with co-existent OSA and identify an important target group for OSA screening and treatment pathways in preparation for major surgery. METHODS: Patients attending a high-risk preadmission clinic prior to major surgery from May 2015 to November 2015 were prospectively screened for OSA using the STOP-BANG questionnaire. Patients with treated OSA were excluded. Patient data and complications were attained from the pre-admission clinic and subsequent inpatient medical record at discharge. RESULTS: Three-hundred-and-ten patients were included in the study (age 68.6 ± 13.1 years, body mass index [BMI] 30.6 ± 7.4 kg/m2; 52.9% female). Sixty-four patients (20.6%) experienced 82 post-operative complications. Seventy-five percent of the cohort had a STOP-BANG ≥ 3. There was no association between the STOP-BANG score (unadjusted and adjusted for comorbidity) with the development of post-operative complications. CONCLUSIONS: OSA predicted by the STOP-BANG score was not associated with higher rates of post-operative complications in patients with major comorbidities undergoing high-risk surgery. As the findings from this cohort contrast with other observational studies, more definitive studies are required to establish a causative link between OSA and post-operative complications and determine whether treating OSA reduces this complication rate.

Home mechanical ventilation in Australia and New Zealand.

This study aims to describe the pattern of home mechanical ventilation (HMV) usage in Australia and New Zealand. 34 centres providing HMV in the region were identified and asked to complete a questionnaire regarding centre demographics, patient diagnoses, HMV equipment and settings, staffing levels and methods employed to implement and follow-up therapy. 28 (82%) centres responded, providing data on 2,725 patients. The minimum prevalence of HMV usage was 9.9 patients per 100,000 population in Australia and 12.0 patients per 100,000 population in New Zealand. Variation existed across Australian states (range 4-13 patients per 100,000 population) correlating with population density (r=0.82; p<0.05). The commonest indications for treatment were obesity hypoventilation syndrome (OHS) (31%) and neuromuscular disease (NMD) (30%). OHS was more likely to be treated in New Zealand, in smaller, newer centres, whilst NMD was more likely to be treated in Australia, in larger, older centres. Chronic obstructive pulmonary disease was an uncommon indication (8.0%). No consensus on indications for commencing treatment was found. In conclusion, the prevalence of HMV usage varies across Australia and New Zealand according to centre location, size and experience. These findings can assist HMV service planning locally and highlight trends in usage that may be relevant in other countries.

A case of extreme carboxyhaemoglominemia due to vaping.

Acute carbon monoxide (CO) poisoning is known to cause neurological, metabolic and cardiorespiratory sequalae. However, data on chronic CO exposure are scant, particularly in the context of vaping, which recent literature suggests may be a greater source of CO than tobacco cigarette smoking. During a series of admissions at the time of vaping, our patient repeatedly presented with significant CO poisoning and developed pulmonary arterial hypertension with resultant high-output right heart failure. On each occasion, our patient's levels of carboxyhaemoglobin were both higher and took longer to resolve than 12 smokers who underwent arterial blood gas testing at two time points. Our observation may reveal an association between vaping, chronic carboxyhaemoglobinemia and the development of cardiorespiratory disease. Thus, further studies into the safety of vaping and chronic CO exposure are urged.

Arterio-VENouS Intra Subject agreement for blood gases within intensive care: The AVENSIS study.

BACKGROUND: In critically ill patients, who require multiple blood gas assessments, agreement between arterial and venous blood gas values for pH and partial pressure of carbon dioxide, is not clear. Good agreement would mean that venous values could be used to assess ventilation and metabolic status of patients in intensive care unit. METHODS: All adult patients admitted to Alfred intensive care unit, Melbourne, from February 2013 to January 2014, who were likely to have arterial and central venous lines for three days, were enrolled. Patients on extra-corporeal life support and pregnant women were excluded. After enrolment, near simultaneous arterial and central venous sampling and analysis were performed at least once per nursing shift till the lines were removed or the patient died. Bland-Altman analysis for repeated measures was performed to assess the agreement between arterio-venous pH and partial pressure of carbon dioxide. RESULTS: A total of 394 paired blood gas analyses were performed from 59 participants. The median (IQR) number of samples per patient was 6 (5-9) with the median (IQR) sampling interval 9.4 (5.2-18.5) h. The mean bias for pH was + 0.036 with 95% limits of agreement ranging from - 0.005 to + 0.078. For partial pressure of carbon dioxide, the values were -2.58 and -10.43 to + 5.27 mmHg, respectively. CONCLUSIONS: The arterio-venous agreement for pH in intensive care unit patients appears to be acceptable. However, the agreement for partial pressure of carbon dioxide was poor.