Abstract Introduction Positional hypoxemia is a decrease in arterial oxygen saturation related to changes in body position. It is typically caused by cardiopulmonary conditions such as ventilation-perfusion (V/Q) mismatch, intracardiac or intrapulmonary shunts, or atelectasis. However, iatrogenic factors like central venous catheters, especially tunneled dialysis catheters (permacaths), are often overlooked. Case Presentation A 78-year-old man with end-stage renal disease (ESRD) on hemodialysis via a right internal jugular permacath placed four months prior, diabetes, heart failure with preserved ejection fraction, and hypertension, presented with altered mental status. Laboratory tests confirmed a hyperosmolar hyperglycemic state (HHS). He developed respiratory distress requiring bilevel positive airway pressure (BiPAP), and a right radial arterial line was placed for blood gas monitoring.In the ICU, his oxygen saturation remained stable at 98-99% while supine on BiPAP. However, when repositioned onto his right side for comfort, oxygen saturation dropped to 89-90%, despite unchanged ventilatory settings and mask seal. Arterial blood gases confirmed hypoxemia. Returning to the supine position quickly restored saturation to normal levels. This pattern repeated consistently with right lateral positioning, without any changes in breath sounds, respiratory effort, or hemodynamics. Discussion In this case, common causes of positional hypoxemia such as V/Q mismatch, atelectasis, or shunting were considered unlikely due to normal imaging, stable respiratory mechanics, and rapid correction upon repositioning. The most likely cause was mechanical or hemodynamic effects from the right internal jugular permacath. The catheter may have compressed nearby vessels or disrupted venous return when the patient lay on his right side, impairing pulmonary blood flow. Changes in intrathoracic pressure with position, especially in an elderly patient with cardiac disease, may have exacerbated this. The reproducible desaturation only in the right lateral decubitus position, with immediate improvement when supine, supports this hypothesis. Although rare, catheter-related positional hypoxemia should be considered in patients with central venous devices and unexplained desaturation, as prompt recognition and management can improve outcomes. References: Hsu, C.W., et al. (2015) ;Central venous catheters and positional hypoxemia in critically ill patients Critical Care Medicine, 43(8), 1675-1680. Kearns, S., et al. (2018) ;Understanding the risks of central venous catheters: A review; Journal of Vascular Access, 19(1), 54-62.s. This abstract is funded by: None
Tayyab et al. (Fri,) studied this question.