Abstract Rationale Hypophosphatemia affects about one-third of intensive care unit (ICU) patients and is linked to longer hospital stays, illness severity and poor outcomes, yet guidelines for monitoring and correction remain unclear. Studies show a strong association between hypophosphatemia and both prolonged invasive mechanical ventilation (IMV) and weaning failure in patients with respiratory failure, due to reduced adenosine triphosphate generation and weakened respiratory muscle performance. Although phosphate abnormalities correlate with higher mortality in sepsis and septic shock, their impact on IMV duration in this population remains unclear. Therefore, we aimed to evaluate the independent association between hypophosphatemia during ICU stay and the duration of IMV in patients with septic shock. Methods We studied adult patients with septic shock admitted to the medical ICU at Mayo Clinic, Rochester, between March 1, 2006, and April 17, 2018. A retrospective analysis was conducted to examine the association between hypophosphatemia—defined as any serum phosphate level 2.5 mg/dL during the ICU stay—and the duration of IMV in hours. The following linear regression models were used: 1, unadjusted; 2, adjusted for baseline demographics (age, sex, weight); 3, adjusted for baseline respiratory comorbidities and Charlson Comorbidity Index (CCI); and 4, adjusted for illness severity (using APACHE III and SOFA scores) and oxygenation (minimum PaO2/FiO2 score during ICU stay). For each model, the β-coefficient was reported, which represents additional hours of IMV associated with hypophosphatemia, along with 95% confidence intervals and p-values. Results The study included 1082 patients, among them 653 (60.4%) required IMV. 53.6% (n = 350) developed hypophosphatemia during their ICU stay. The mean duration of IMV was significantly longer in patients with hypophosphatemia compared with those without (184 ± 218 h vs 100 ± 126 h; p 0.001; 95% CI 56-112). This association persisted across all multivariable linear regression models. After adjustment for baseline demographics, hypophosphatemia remained significantly associated with longer IMV duration (β = 79.8 h; 95% CI 51.8-107.8; p 0.001). Further adjustment for respiratory comorbidities and CCI yielded similar results (β = 81.8 h; 95% CI 54.2-109.4; p 0.001). After controlling for illness severity and oxygenation status, hypophosphatemia remained independently associated with prolonged IMV duration (β = 69.2 h; 95% CI 39.9-98.4; p 0.001). Conclusion Hypophosphatemia was independently associated with longer duration of IMV in patients with septic shock, which prolongs ICU level care and delays rehabilitation. This highlights the need for updates on guidelines for maintaining optimal serum phosphate levels in patients who are mechanically ventilated. This abstract is funded by: None
Guardia et al. (Fri,) studied this question.