P006 Initiation of Continuous Positive Airway Pressure as an inpatient in Patients with Obesity Hypoventilation Syndrome admitted to General Medical Unit

Background With higher rates of obesity in regional and rural Australian population, there will be higher rates of Obesity Hypoventilation Syndrome (OHS). The cornerstone of the treatment of OHS is Positive Airways Pressure. We studied the initiation of Continuous Positive Airways Pressure (CPAP) in an inpatient setting in patients with OHS in the regional population of Ballarat and subsequent impact on their hospital stay/readmission. Methods We performed a retrospective study of 22 patients with OHS during the 6-month study period (01/07/2021–31/12/2021) admitted into General Medical Unit at Ballarat Base Hospital. Progress Complete Outcome/Impact The mean age in the cohort was 60 with average weight of 139.5 kg. The mean pCO2 and pH were 68.1 and 7.33 respectively. CPAP was initiated in 9 of 22 patients (40.1%) with mean of 7.3 days. Mean days of oxygen use was 4.7 days with mean length of hospital stay 10 days. We did not find any statistical difference in length of hospital stay, ICU stay, supplemental oxygen use or readmission rates between CPAP and non-CPAP group. Subgroup analysis showed that CPAP group had higher rates of COPD (44.4% vs 30.8%) and diabetes (44.4% vs 30.8%) with trend to lower FEV1 (mean FEV1 47.6% vs 57.2%). There were 4 deaths (16.7%), 3 of them did not have CPAP initiated. The longer duration to CPAP initiation is likely to explain the non-significant difference between the groups. Proactive measures to increase initiation of CPAP is likely to improve patient outcome in terms of their morbidity and mortality.

Mutations of PHOX2B Gene in Patients of Obesity Hypoventilation Syndrome in Central India

Background Paired-like homeobox 2B (PHOX2B) gene on chromosome 4p12 codes for a transcription factor having a role in the formation of noradrenergic neuronal circuits. Its mutations have been linked to congenital central hypoventilation syndrome (CCHS). The clinical presentation of both, obesity hypoventilation syndrome (OHS) and CCHS in adults (named late-onset central hypoventilation syndrome), is quite similar. Because of this symptomatic similarity, multifactorial causation of OHS, the mutation of PHOX2B gene was studied in patients with OHS in this study. Methods A hospital-based cross-sectional study was performed on patients diagnosed with OHS. The deoxyribonucleic acid was extracted from 2 mL of venous blood and was further amplified, specific to exon 3. The amplified products were cast and run in 2% agarose gel and then subjected to Sanger sequencing. Results Thirty patients of OHS (21 male; 9 female) were enrolled in the present study, average age being 51.7 years. The Sanger sequencing of the samples revealed no apparent areas of deletions and no apparent mutations. Conclusion Primers for exon 3 were used for amplification in thermocycler, as exon 3 is the most frequently mutated exon for PHOX2B gene, as per existing literature. The entire gene needs to be studied for mutations and the sample size needs to be increased.