Polymyxin B-induced Bartter syndrome.

Bartter syndrome is a genetic disorder characterised by chloride-unresponsive metabolic alkalosis, hypokalaemia, hypomagnesaemia and hypercalciuria. While it commonly presents antenatally or in early infancy, sometimes, drugs can induce a state similar to Bartter syndrome in any age group, called acquired Bartter syndrome. Polymyxins and aminoglycosides are the most commonly implicated drugs. Polymyxin B and polymyxin E (popularly known as colistin) are the two chemically similar polymyxins that are commonly used clinically. While colistin is frequently associated with nephrotoxicity, polymyxin B is generally considered less nephrotoxic. This difference is due to the way these two drugs are handled by the kidneys. In this case report, we discuss a middle-aged male who developed Bartter syndrome due to polymyxin B, which resolved on discontinuation of the drug, and re-appeared after its re-introduction later. This case exemplifies the nephrotoxicity caused by polymyxin B and the need for vigilance when using this drug.

Ultrasonography of the neck in patients with obstructive sleep apnea.

INTRODUCTION: In resource-limited settings, obstructive sleep apnea (OSA) often goes undiagnosed as polysomnography (PSG) is expensive, time-consuming, and not readily available. Imaging studies of upper airway have been tried as alternatives to PSG to screen for OSA. However, racial differences in upper airway anatomy preclude generalizability of such studies. We sought to test the hypothesis that ultrasonography (USG), an inexpensive, readily available tool to study soft tissue structures of the upper airway, would have predictive value for OSA in South Asian people. METHODS: Adult patients with sleep-related complaints suspicious for OSA were taken for overnight PSG. After the PSG, consecutive patients with and without OSA were studied with submental ultrasonography to measure tongue base thickness (TBT) and lateral pharyngeal wall thickness (LPWT). RESULTS: Among 50 patients with OSA and 25 controls, mean age was 43.9 ± 11.4 years, and 39 were men. Patients with OSA had higher TBT (6.77 ± 0.63 cm vs 6.34 ± 0.54 cm, P value = 0.004) and higher LPWT (2.47 ± 0.60 cm vs 2.12 ± 0.26 cm, P value = 0.006) compared to patients without OSA. On multivariate analysis, TBT, LPWT, and neck circumference were identified as independent factors associated with OSA. These variables could identify patients with severe OSA with a sensitivity of 72% and a specificity of 76%. CONCLUSION: Patients with OSA have higher tongue base thickness and lateral pharyngeal wall thickness proportionate to the severity of the disease, independent of BMI and neck circumference. These findings suggest that sub-mental ultrasonography may be useful to identify patients with severe OSA in resource-limited settings.

Pneumothorax and pneumomediastinum in patients with COVID-19: A retrospective study from tertiary care institute in India.

COVID-19 is associated with rarer extra-parenchymal manifestations, namely pneumothorax (PTX) and pneumomediastinum (PM) leading to complications and increased mortality. The study aims to describe the prevalence, risk factors for mortality, radiological characteristics and outcome of PTX/PM in patients admitted with COVID-19. This was a retrospective, single-centre, observational study in patients with confirmed COVID-19 presenting with non-iatrogenic PTX/PM from April 2020 to May 2021. Details pertaining to demographics, presentation, radiological characteristics, management and outcome were collected. Cases were classified into spontaneous and barotraumatic PTX/PM and a between-group comparison was performed using Chi-square and t-test. A total of 45 cases (mean age: 53.2 years, 82% males) out of 8,294 confirmed COVID-19 patients developed PTX/PM, the calculated incidence being 0.54%. 29 cases had spontaneous PTX/PM and the remaining 17 cases were attributed to barotrauma. The most common comorbidities were diabetes-mellitus (65.3%) and hypertension (42.3%). The majority of the cases had large PTX (62.1%) with tension in 8 cases (27.5%). There were predominant right-sided pneumothoraces and five were diagnosed with bronchopleural fistula. 37.7% of cases had associated subcutaneous emphysema. The median duration of PTX/PM from symptom onset was delayed at 22.5 and 17.6 days respectively. The mean CT severity score (CTSS) was 20.5 (± 4.9) with fibrosis (53.8%), bronchiectatic changes (50%) and cystic-cavitary changes (23%). There was no statistically significant difference between the spontaneous and barotrauma cohort. 71% of cases died and the majority belonged to the barotrauma cohort. It is imperative to consider the possibility of PTX/PM in patients having COVID-19, especially in those with deterioration in the disease course, both in spontaneously breathing and mechanically ventilated patients. These patients may also have a high incidence of death, reflecting the gravity of COVID-19.