Association of Arterial pH With Hemodynamic Response to Vasopressin in Patients With Septic Shock: An Observational Cohort Study

Impact of AKI on metabolic compensation for respiratory acidosis in ICU patients with AECOPD

PURPOSE

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) can result in severe respiratory acidosis. Metabolic compensation is primarily achieved by renal retention of bicarbonate. The extent to which acute kidney injury (AKI) impairs the kidney's capacity to compensate for respiratory acidosis remains unclear.

MATERIALS AND METHODS

This retrospective analysis covers clinical data between January 2009 and December 2021 for 498 ICU patients with AECOPD and need for respiratory support.

RESULTS

278 patients (55.8%) presented with or developed AKI. Patients with AKI exhibited higher 30-day-mortality rates (14.5% vs. 4.5% p = 0.001), longer duration of mechanical ventilation (median 90 h vs. 14 h; p = 0.001) and more severe hypercapnic acidosis (pH 7.23 vs. 7.28; pCO2 68.5 mmHg vs. 61.8 mmHg). Patients with higher AKI stages exhibited lower HCO3-/pCO2 ratios and did not reach expected HCO3- levels. In a mixed model analysis with random intercept per patient we analyzed the association of pCO2 (independent) and HCO3- (dependent variable). Lower estimates for averaged change in HCO3- were observed in patients with more severe AKI.

CONCLUSION

AKI leads to poor outcomes and compromises metabolic compensation of respiratory acidosis in ICU patients with AECOPD. While buffering agents may aid compensation for severe AKI, their use should be approached with caution.

A Clinical Review of Vasopressors in Emergency Medicine

BACKGROUND

Vasopressor medications raise blood pressure through vasoconstriction and are essential in reversing the hypotension seen in many critically ill patients. Previously, vasopressor administration was largely limited to continuous infusions through central venous access.

OBJECTIVES OF THE REVIEW

This review addresses the clinical use of vasopressors in various shock states, including practical considerations and innovations in vasopressor administration. The focus is on the clinical administration of vasopressors across a range of shock states, including hypovolemic, distributive, cardiogenic, and obstructive shock.

DISCUSSION

Criteria for starting vasopressors are not clearly defined, though early use may be beneficial. A number of physiologic factors affect the body's response to vasopressors, such as acidosis and adrenal insufficiency. Peripheral and push-dose administration of vasopressors are becoming more common. Distributive shock is characterized by inappropriate vasodilation and vasopressors play a crucial role in maintaining adequate blood pressure. The use of vasopressors is more controversial in hypovolemic shock, as the preferred treatment is correction of the volume deficit. Evidence for vasopressors is limited in cardiogenic shock. For obstructive shock, vasopressors can temporize a patient's blood pressure until definitive therapy can reverse the underlying cause.

CONCLUSION

Across the categories of shock states, norepinephrine has wide applicability and is a reasonable first-line agent for shock of uncertain etiology. Keeping a broad differential when hypotension is refractory to vasopressors may help to identify adjunctive treatments in physiologic states that impair vasopressor effectiveness. Peripheral administration of vasopressors is safe and facilitates early administration, which may help to improve outcomes in some shock states.

asopressin nitiation as a econd-Line Vasoressor in Early eptic hock (VISPSS)

BACKGROUND

Vasopressin is recommended as a second-line vasoactive agent for the management of septic shock; however, a paucity of data to guide its optimal use remains. The aim was to evaluate the effect of time-to vasopressin initiation and norepinephrine (NE) dose at vasopressin initiation on clinical outcomes in patients presenting with septic shock.

METHODS

This was a multi-centered, retrospective, observational study conducted in patients with septic shock. Patients were divided into 2 groups: patients initiated on vasopressin when NE-equivalent dose (NEE) < 0.25 mcg/kg/min or ≥ 0.25 mcg/kg/min. The primary outcome was time-to-vasopressor discontinuation (hours). Secondary outcomes included 28-day in-hospital mortality, intensive care unit (ICU) length of stay (LOS), fluid balance after 72 hours, and the change in NEE at 12 hours.

RESULTS

A total of 302 patients were included in this study. After propensity-score matching, 73 patients in each group were identified for analysis. There was no significant difference in the time-to-vasopressor discontinuation (hours) between the groups (88.8 [55-187.5] vs 86.7 [47-172]); p = 0.7815). Fluid balance (mL) at 72 hours was significantly lower when vasopressin was initiated at NEE < 0.25 mcg/kg/min (1769 [71-7287] vs 5762 [1463-8813]; p = 0.0077). A multivariable linear regression showed shorter time to shock resolution with earlier vasopressin initiation, defined as within 4 hours (p < 0.05).

CONCLUSION

In this propensity-score matched cohort, vasopressin initiation at NEE < 0.25 mcg/kg/min was not associated with shorter vasopressor duration. There was a lower fluid balance at 72 hours when vasopressin was initiated at lower NE doses.

Precision fluid and vasoactive drug therapy for critically ill patients

There are several clinical practice guidelines concerning the use of fluid and vasoactive drug therapies in critically ill adult patients, but the recommendations in these guidelines are often based on low-quality evidence. Further, some were compiled prior to the publication of landmark clinical trials, particularly in the comparison of balanced crystalloid and normal saline. An important consideration in the treatment of critically ill patients is the application of precision medicine to provide the most effective care to groups of patients most likely to benefit from the therapy. Although not currently widely integrated into these practice guidelines, the utility of precision medicine in critical illness is a recognized research priority for fluid and vasoactive therapy management. The purpose of this narrative review was to illustrate the evaluation and challenges of providing precision fluid and vasoactive therapies to adult critically ill patients. The review includes a discussion of important investigations published after the release of currently available clinical practice guidelines to provide insight into how recommendations and research priorities may change future guidelines and bedside care for critically ill patients.

Echocardiographic profiles and hemodynamic response after vasopressin initiation in septic shock: A cross-sectional study

PURPOSE

Vasopressin, used as a catecholamine adjunct, is a vasoconstrictor that may be detrimental in some hemodynamic profiles, particularly left ventricular (LV) systolic dysfunction. This study tested the hypothesis that echocardiographic parameters differ between patients with a hemodynamic response after vasopressin initiation and those without a response.

METHODS

This retrospective, single-center, cross-sectional study included adults with septic shock receiving catecholamines and vasopressin with an echocardiogram performed after shock onset but before vasopressin initiation. Patients were grouped by hemodynamic response, defined as decreased catecholamine dosage with mean arterial pressure ≥ 65 mmHg six hours after vasopressin initiation, with echocardiographic parameters compared. LV systolic dysfunction was defined as LV ejection fraction (LVEF) <45%.

RESULTS

Of 129 included patients, 72 (56%) were hemodynamic responders. Hemodynamic responders, versus non-responders, had higher LVEF (61% [55%,68%] vs. 55% [40%,65%]; p = 0.02) and less-frequent LV systolic dysfunction (absolute difference  -16%; 95% CI -30%,-2%). Higher LVEF was associated with higher odds of hemodynamic response (for each LVEF 10%, response OR 1.32; 95% CI 1.04-1.68). Patients with LV systolic dysfunction, versus without LV systolic dysfunction, had higher mortality risk (HR(t) = e[0.81-0.1*t]; at t = 0, HR 2.24; 95% CI 1.08-4.64).

CONCLUSIONS

Pre-drug echocardiographic profiles differed in hemodynamic responders after vasopressin initiation versus non-responders.

Timing of vasopressin initiation and mortality in patients with septic shock: analysis of the MIMIC-III and MIMIC-IV databases

BACKGROUND

vasopressin is commonly used as a second-line vasopressor for patients with septic shock, but the optimal timing of initiation is uncertain. This study was designed to investigate when vasopressin initiation may be beneficial for 28-day mortality in septic shock patients.

METHODS

This was a retrospective observational cohort study from the MIMIC-III v1.4 and MIMIC-IV v2.0 databases. All adults diagnosed with septic shock according to Sepsis-3 criteria were included. Patients were stratified into two groups based on norepinephrine (NE) dose at the time of vasopressin initiation, defined as the low doses of NE group (NE<0.25 µg/kg/min) and the high doses of NE group (NE ≥ 0.25 µg/kg/min). The primary end-point was 28-day mortality after diagnosis of septic shock. The analysis involved propensity score matching (PSM), multivariable logistic regression, doubly robust estimation, the gradient boosted model, and an inverse probability-weighting model.

RESULTS

A total of 1817 eligible patients were included in our original cohort (613 in the low doses of NE group and 1204 in the high doses of NE group). After 1:1 PSM, 535 patients from each group with no difference in disease severity were included in the analysis. The results showed that vasopressin initiation at low doses of NE was associated with reduced 28-day mortality (odds ratio [OR] 0.660, 95% confidence interval [CI] 0.518-0.840, p < 0.001). Compared with patients in the high doses of NE group, patients in the low doses of NE group received significantly shorter duration of NE, with less intravenous fluid volume on the first day after initiation of vasopressin, more urine on the second day, and longer mechanical ventilation-free days and CRRT-free days. Nevertheless, there were no significant differences in hemodynamic response to vasopressin, duration of vasopressin, and ICU or hospital length of stay.

CONCLUSIONS

Among adults with septic shock, vasopressin initiation when low-dose NE was used was associated with an improvement in 28-day mortality.

Red cell distribution width and in-hospital mortality in septic shock: A public database research

OBJECTIVE

This study aimed to explore the relationship between red cell distribution width (RDW) and in-hospital mortality in septic shock based on a large-scale public database.

METHODS

All patients with septic shock in MIMIC-IV were enrolled. Based on RDW values, the general characteristics of different groups were compared. Different models were constructed for exploring the association of RDW and in-hospital mortality. To assess the predictive value of RDW, receiver operator characteristic (ROC) curve analysis was applied.

RESULTS

A total of 3006 patients with septic shock were included and in-hospital mortality was 32.27% (n = 970). The results of the fully adjusted model demonstrated that RDW was positively associated with in-hospital mortality in septic shock patients after adjusting all confounders (OR = 1.12, 95% CI:1.08-1.17, p < .001). A linear relationship between RDW and in-hospital mortality was found. For predicting in-hospital mortality, the area under the ROC curve (AUC) of RDW was .602 and the best threshold of RDW was 17.25%.

CONCLUSION

RDW was associated with in-hospital mortality in septic shock. It could be a useful marker for predicting clinical outcomes in septic shock.