Heart rate is crucial for patients with septic shock, but there are few studies on the scope of heart rate. Therefore, we studied the relationship between different heart rates and mortality of critically ill patients with septic shock, and explored the optimal heart rate range, in order to provide new insights for clinical treatment of septic shock. This retrospective study utilized time-series heart rate data from the Medical Information Mart for Intensive Care (MIMIC) IV database. Patients with septic shock were identified as the Sepsis 3.0 criteria and received vasopressor therapy in the first 24 h since ICU admission. We calculated the time-weighted average heart rate (TWA-HR) based on the time-series data. The restricted cubic spline (RCS) analysis was employed to investigate the nonlinear relationship between heart rate and 28-day mortality, aiming to explore the optimal heart rate control target for septic patients and using this target as the exposure factor. The primary outcome was 28-day mortality, and the secondary outcome were ICU and in-hospital mortality. For the original cohort, we applied the log-rank test to infer the relationship between heart rate and mortality. To control for bias introduced by confounders, we utilized propensity score matching (PSM) to reduce imbalances between normal TWA-HR and high TWA-HR groups, and we established a series of models [the multivariable Cox model, matching weight (MW)-adjusted Cox model, multivariable logistic regression, MW-adjusted logistic regression, and doubly robust model] as sensitivity analyses and subgroup analyses to demonstrate the robustness of our findings. A total of 13492 patients were included in our study. The RCS analysis based on Cox and logistic regression showed increased risk of mortality (P < 0.001, non-linear P < 0.001) when TWA-HR > 85 beats per minute (bpm). The log-rank test revealed in terms of the 28-day mortality, the hazard ratio (HR) (95% confidence interval [CI]) was 1.92 (1.78—2.06, P < 0.001) for patients with high TWA-HR compared to normal TWA-HR group. Similarly, for the ICU mortality, the HR (95% CI) was 1.64 (1.52—1.78, P < 0.001), and for the in-hospital mortality, the HR (95% CI) was 1.61 (1.48—1.76, P < 0.001). Collectively, the sensitivity analysis consistently demonstrated higher 28-day mortality, ICU mortality, and in-hospital mortality in patients with TWA-HR > 85 bpm. Patients with septic shock whose heart rate was controlled no more than 85 bpm during ICU stay received survival benefit in terms of 28-day, ICU and in-hospital mortality.

Objective: The study aimed to evaluate the relationship between serum sodium and mortality in critically ill patients with non-traumatic subarachnoid hemorrhage.Methods: This is a retrospective investigation of critically ill non-traumatic patients with subarachnoid hemorrhage (SAH) utilizing the MIMIC-IV database. We collected the serum sodium levels at admission and determined the all-cause death rates for the ICU and hospital. We employed a multivariate Cox proportional hazard regression model and Kaplan–Meier survival curve analysis to ascertain the relationship between serum sodium and all-cause mortality. In order to evaluate the consistency of correlations, interaction and subgroup analyses were also conducted.Results: A total of 864 patients with non-traumatic SAH were included in this study. All-cause mortality in the ICU and hospital was 32.6% (282/864) and 19.2% (166/864), respectively. Sodium levels at ICU admission showed a statistically significant J-shaped non-linear relationship with ICU and hospital mortality (non-linear P-value < 0.05, total P-value < 0.001) with an inflection point of ~141 mmol/L, suggesting that mortality was higher than normal serum sodium levels in hypernatremic patients. Multivariate analysis after adjusting for potential confounders showed that high serum sodium levels (≥145 mmol/L) were associated with an increased risk of all-cause mortality in the ICU and hospital compared with normal serum sodium levels (135–145 mmol/L), [hazard ratio (HR) = 1.47, 95% CI: 1.07–2.01, P = 0.017] and (HR = 2.26, 95% CI:1.54–3.32, P < 0.001). Similarly, Kaplan–Meier (K-M) survival curves showed lower survival in patients with high serum sodium levels. Stratified analysis further showed that the association between higher serum sodium levels and hospital all-cause mortality was stronger in patients aged < 60 years with a hospital stay of <7 days.Conclusion: High serum sodium levels upon ICU admission are related to higher ICU and hospital all-cause mortality in patients with non-traumatic SAH. A new reference is offered for control strategies to correct serum sodium levels.

Background: In critically ill patients, transcutaneous oxygen saturation (SpO₂) upon admission is typically associated with in-hospital mortality. Nevertheless, the available information for patients with non-traumatic subarachnoid hemorrhage (SAH) is limited. In our study, our objective was to assess the correlation between SpO₂ levels and mortality among patients diagnosed with severe SAH.Methods: In this study, we extracted data from the Medical Information Marketplace in Intensive Care (MIMIC-IV) database, which comprises information on critically ill patients. By employing matching ICD-9 and ICD-10 codes, we identified 3,328 patients diagnosed with SAH. Every individual who was admitted to the intensive care unit (ICU) had their SpO₂ data and various covariates, including age, sex, diagnosis, and duration of stay, recorded upon admission. Subsequently, the patients were categorized into three distinct groups according to their SpO₂ levels: low (≤95%), moderate (95–98%), and high (≥98%). To investigate the association between percutaneous oxygen saturation and mortality in patients with severe SAH, logistic regression, and cubic spline models were utilized. The main outcomes of interest were 28- and 90-day mortality rates. Additionally, subgroup analyses were conducted to evaluate these correlations and assess the consistency of interactions.Results: A cohort of 864 patients diagnosed with non-traumatic SAH was included in this study. The correlation between SpO₂ and mortality displayed a U-shaped curve when utilizing a finite cubic spline function (non-linearity < 0.001), with the nadir in the probability of in-hospital death at 96%. Mortality at 28 and 90 days showed an inverse correlation with SpO₂ < 96% (adjusted odds ratio [OR], 0.8; 95% confidence interval [CI], 0.67–0.95, and 0.76; 95% CI, 0.6–0.96). Conversely, there was a positive correlation between percutaneous oxygen saturation (SpO₂) levels of ≥96% and mortality rates at both 28 and 90 days (adjusted OR, 1.17; 95% CI, 1.02–1.35 and 1.2; 95% CI, 1.05–1.39).Conclusion: In patients with severe subarachnoid hemorrhage, the association between SpO₂ and mortality at 28 and 90 days demonstrated a U-shaped pattern. When SpO₂ levels were between 95 and 98%, both short- and long-term mortality rates were at their lowest. Patients with significant subarachnoid hemorrhage had a lower chance of survival when their SpO₂ values were either high or low.