Liberal vs. conservative vasopressor use to maintain mean arterial blood pressure during resuscitation of septic shock: an observational study

Hospital Outcomes in Patients Who Developed Acute Respiratory Distress Syndrome After Community-Acquired Pneumonia

Purpose: To identify risk factors for and outcomes in acute respiratory distress syndrome (ARDS) in patients hospitalized with community-acquired pneumonia (CAP). Methods: This is a retrospective study using the Premier Healthcare Database between 2016 and 2020. Patients diagnosed with pneumonia, requiring mechanical ventilation (MV), antimicrobial therapy, and hospital admission ≥2 days were included. Multivariable regression models were used for outcomes including in-hospital mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on MV. Results: 1924 (2.7%) of 72 107 patients with CAP developed ARDS. ARDS was associated with higher mortality (33.7% vs 18.9%; adjusted odds ratio 2.4; 95% confidence interval [CI] 2.16-2.66), longer hospital LOS (13 vs 9 days; adjusted incidence risk ratio (aIRR) 1.24; 95% CI 1.20-1.27), ICU LOS (9 vs 5 days; aIRR 1.51; 95% CI 1.46-1.56), more MV days (8 vs 5; aIRR 1.54; 95% CI 1.48-1.59), and increased hospitalization cost ($46 459 vs $29 441; aIRR 1.50; 95% CI 1.45-1.55). Conclusion: In CAP, ARDS was associated with worse in-patient outcomes in terms of mortality, LOS, and hospitalization cost. Future studies are needed to explore outcomes in patients with CAP with ARDS and explore risk factors for development of ARDS after CAP.

INITIATION TIMING OF VASOPRESSOR IN PATIENTS WITH SEPTIC SHOCK: A SYSTEMATIC REVIEW AND META-ANALYSIS

ABSTRACT

Background: Vasopressor plays a crucial role in septic shock. However, the time for vasopressor initiation remains controversial. We conducted a systematic review and meta-analysis to explore its initiation timing for septic shock patients. Methods: PubMed, Cochrane Library, Embase, and Web of Sciences were searched from inception to July 12, 2023, for relevant studies. Primary outcome was short-term mortality. Meta-analysis was performed using Stata 15.0. Results: Twenty-three studies were assessed, including 2 randomized controlled trials and 21 cohort studies. The early group resulted in lower short-term mortality than the late group (OR [95% CI] = 0.775 [0.673 to 0.893], P = 0.000, I2 = 67.8%). The significance existed in the norepinephrine and vasopressin in subgroup analysis. No significant difference was considered in the association between each hour's vasopressor delay and mortality (OR [95% CI] = 1.02 [0.99 to 1.051], P = 0.195, I2 = 57.5%). The early group had an earlier achievement of target MAP ( P < 0.001), shorter vasopressor use duration ( P < 0.001), lower serum lactate level at 24 h ( P = 0.003), lower incidence of kidney injury ( P = 0.001), renal replacement therapy use ( P = 0.022), and longer ventilation-free days to 28 days ( P < 0.001). Conclusions: Early initiation of vasopressor (1-6 h within septic shock onset) would be more beneficial to septic shock patients. The conclusion needs to be further validated by more well-designed randomized controlled trials.

Effect of restrictive cumulative fluid balance on 28-day survival in invasively ventilated patients with moderate to severe ARDS due to COVID-19

This study aimed to evaluate the effect of two restrictive cumulative fluid balance (CFB) trends on survival and on major clinical outcomes in invasively ventilated patients with moderate to severe respiratory distress syndrome (ARDS) due to SARS-CoV-2. Prospective data collection was conducted on patients in the intensive care unit (ICU) originating from a tertiary university hospital. The primary outcomes were the risk association between the CFB trend during D0 to D7 and 28-day survival. The secondary outcomes were ICU mortality, in-hospital mortality, the need for invasive ventilation at D28, administration of vasoactive drugs at D7, time on invasive ventilation after D7, and length of ICU and hospital stay. 171 patients were enrolled in the study and divided according to their CFB trends during seven days of follow-up using model-based clustering [median CFB negative trend (n = 89) - 279 ml (- 664 to 203) and (n = 82) median CFB positive trend 1362 ml (619-2026)]. The group with CFB negative trend showed a higher chance of surviving 28-day in the ICU (HR: 0.62, 95% CI 0.41-0.94, p = 0.038). Moreover, this group had a reduced length of stay in the ICU, 11 (8-19) days versus 16.5 (9-29) days p = 0.004 and presented lower rates (OR = 0.22; 95% CI 0.09-0.52) of invasive ventilation after 28-days in the ICU. In patients invasively ventilated with moderate to severe ARDS due to COVID-19, the collective who showed a negative trend in the CFB after seven days of invasive ventilation had a higher chance of surviving 28 days in the ICU and lower length of stay in the ICU.

Timing of vasoactive agents and corticosteroid initiation in septic shock

Septic shock remains a health care concern associated with significant morbidity and mortality. The Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock recommend early fluid resuscitation and antimicrobials. Beyond initial management, the guidelines do not provide clear recommendations on appropriate time to initiate vasoactive therapies and corticosteroids in patients who develop shock. This review summarizes the literature regarding time of initiation of these interventions. Clinical data regarding time of initiation of these therapies in relation to shock onset, sequence of treatments with regard to each other, and clinical markers evaluated to guide initiation are summarized. Early-high vasopressor initiation within first 6 h of shock onset is associated with lower mortality. Following norepinephrine initiation, the exact dose and timing of escalation to adjunctive vasopressor agents are not well elucidated in the literature. However, recent data indicate that timing may be an important factor in initiating vasopressors and adjunctive therapies, such as corticosteroids. Norepinephrine-equivalent dose and lactate concentration can aid in determining when to initiate vasopressin and angiotensin II in patients with septic shock. Future guidelines with clear recommendations on the time of initiation of septic shock therapies are warranted.

Practices of Initiation of Vasoactive Drugs in Relation to Resuscitation Fluids in Children with Septic Shock: A Prospective Observational Study

Background: The role of vasoactive medications in septic shock is well-defined, but the appropriate time of initiation of these medications in reference to fluid boluses is not clear. We planned to study prospectively the practices and outcome of initiation of vasoactive infusions with respect to resuscitation fluids boluses in pediatric septic shock.

Patients and methods: Children aged 1 month to 18 years diagnosed with septic shock were enrolled to receive fluid resuscitation boluses along with vasoactive drugs. The primary outcome was to look at various practices of the initiation of vasoactive infusions; accordingly, patients were categorized into three groups: N1 received vasoactive infusions after completion of the first bolus (20 mL/kg), N2 after the second (40 mL/kg), and N3 after the third fluid (60 mL/kg) bolus. Secondary outcomes were to compare the time taken, amount of fluid required to achieve hemodynamic stability, total fluid required, and complications in the first 24 hours of treatment and mortality.

Results: Hundred children were enrolled and grouped into N1, N2, and N3 with 46, 10, and 44 patients, respectively. The volume of fluid required to achieve the resolution of shock in N1 (40 ± 10 mL/kg) was significantly less than in N2 (70 ± 10 mL/kg) and N3 (70 ± 20 mL/kg); p = 0.02. The time taken to achieve hemodynamic stability was significantly less in N1 (115 ± 45 minutes) than in N2 (196 ± 32 minutes) and N3 (212 ± 44 minutes); p = 0.02. The volume of intravenous fluid required in the first 24 hours (p = 0.02) and complications were lower in the N1 group (p = 0.04). No statistical difference in mortality was seen.

Conclusion: Early initiation of vasoactive infusions (after the first bolus) resulted in less total fluid volume, lesser time to achieve hemodynamic stability, less fluid boluses, less length of stay in the pediatric intensive care unit, and lesser complications in the first 24 hours.

Highlight: Early initiation of vasoactive infusions—after completion of the first fluid bolus resulted in less need for further fluid boluses, lesser time for shock resolution, lesser fluid overload, and less PICU stay—in pediatric septic shock.

How to cite this article: Karanvir, Gupta S, Kumar V. Practices of Initiation of Vasoactive Drugs in Relation to Resuscitation Fluids in Children with Septic Shock: A Prospective Observational Study. Indian J Crit Care Med 2021;25(8):928–933.

Should Vasopressors Be Started Early in Septic Shock?

Sepsis can influence blood volume, its distribution, vascular tone, and cardiac function. Persistent hypotension or the need for vasopressors after volume resuscitation is part of the definition of septic shock. Since increased positive fluid balance has been associated with increased morbidity and mortality in sepsis, timing of vasopressors in the treatment of septic shock seems crucial. However, conclusive evidence on timing and sequence of interventions with the goal to restore tissue perfusion is lacking. The aim of this narrative review is to depict the pathophysiology of hypotension in sepsis, evaluate how common interventions to treat hypotension interfere with physiology, and to give a resume of the results from clinical studies focusing on targets and timing of vasopressor in sepsis. The majority of studies comparing early versus late administration of vasopressors in septic shock are rather small, single-center, and retrospective. The range of "early" is between 1 and 12 hours. The available studies suggest a mean arterial pressure of 60 to 65 mm Hg as a threshold for increased risk of morbidity and mortality, whereas higher blood pressure targets do not seem to add further benefits. The data, albeit mostly from observational studies, speak for combining vasopressors with fluids rather "early" in the treatment of septic shock (within a 0-3-hour window). Nevertheless, the optimal resuscitation strategy should take into account the source of infection, the pathophysiology, the time and clinical course preceding the diagnosis of sepsis, and also comorbidities and sepsis-induced organ dysfunction.

Risk factor identification and predictive models for central line requirements for patients on vasopressors

Vasopressors are ubiquitous in intensive care units. While central venous catheters are the preferred route of infusion, recent evidence suggests peripheral administration may be safe for short, single-agent courses. Here, we identify risk factors and develop a predictive model for patient central venous catheter requirement using the Medical Information Mart for Intensive Care, a single-centre dataset of patients admitted to an intensive care unit between 2008 and 2019. Using prior literature, a composite endpoint of prolonged single-agent courses (>24 hours) or multi-agent courses of any duration was used to identify likely central venous catheter requirement. From a cohort of 69,619 intensive care unit stays, there were 17,053 vasopressor courses involving one or more vasopressors that met study inclusion criteria. In total, 3807 (22.3%) vasopressor courses involved a single vasopressor for less than six hours, 7952 (46.6%) courses for less than 24 hours and 5757 (33.8%) involved multiple vasopressors of any duration. Of these, 3047 (80.0%) less than six-hour and 6423 (80.8%) less than 24-hour single vasopressor courses used a central venous catheter. Logistic regression models identified associations between the composite endpoint and intubation (odds ratio (OR) 2.36, 95% confidence intervals (CI) 2.16 to 2.58), cardiac diagnosis (OR 0.72, CI 0.65 to 0.80), renal impairment (OR 1.61, CI 1.50 to 1.74), older age (OR 1.002, Cl 1.000 to 1.005) and vital signs in the hour before initiation (heart rate, OR 1.006, CI 1.003 to 1.009; oxygen saturation, OR 0.996, CI 0.993 to 0.999). A logistic regression model predicting the composite endpoint had an area under the receiver operating characteristic curve (standard deviation) of 0.747 (0.013) and an accuracy of 0.691 (0.012). This retrospective study reveals a high prevalence of short vasopressor courses in intensive care unit settings, a majority of which were administered using central venous catheters. We identify several important risk factors that may help guide clinicians deciding between peripheral and central venous catheter administration, and present a predictive model that may inform future prospective trials.

Time to vasopressor initiation and organ failure progression in early septic shock

OBJECTIVE

Research evaluating the relationship between vasopressor initiation timing and clinical outcomes is limited and conflicting. We investigated the association between time to vasopressors, worsening organ failure, and mortality in patients with septic shock.

METHODS

This was a retrospective study of patients with septic shock (2013-2016) within 24 hours of emergency department (ED) presentation. The primary outcome was worsening organ failure, defined as an increase in Sequential Organ Failure Assessment (SOFA) score ≥2 at 48 hours compared to baseline, or death within 48 hours. The secondary outcome was 28-day mortality. Time to vasopressor initiation was categorized into 6, 4-hour intervals from time of ED triage. Multiple logistic regression was used to identify predictors of worsening organ failure.

RESULTS

We analyzed data from 428 patients with septic shock. There were 152 patients with the composite primary outcome (SOFA increase ≥2 or death at 48 hours). Of these, 77 patients died in the first 48 hours and 75 patients had a SOFA increase ≥2. Compared to the patients who received vasopressors in the first 4 hours, those with the longest time to vasopressors (20-24 hours) had increased odds of developing worsening organ failure (odds ratios [OR] = 4.34, 95% confidence intervals [CI] = 1.47-12.79, P = 0.008). For all others, the association between vasopressor timing and worsening organ failure was non-significant. There was no association between time to vasopressor initiation and 28-day mortality.

CONCLUSIONS

Increased time to vasopressor initiation is an independent predictor of worsening organ failure for patients with vasopressor initiation delays >20 hours.

Diastolic pressure should be used to guide management of patients in shock: PRO

Based primarily on the rational that adequate diastolic pressure is needed to maintain sufficient coronary blood for myocardial needs, diastolic pressure has been proposed as a treatment target for patients in shock. To date, clinical evidence supporting this is limited to observational data. Key points are that what is important for tissues is flow not pressure; the coronary circulation has very large flow reserves and can maintain flow with a low pressure; raising arterial pressure by only increasing vascular resistance does not alter tissue perfusion and could even increase myocardial oxygen demand. Targeting diastolic pressure can lead to over use of vasopressors, which studies have associated with worse outcome. Pressor management in shock should include assessment of indicators of tissue perfusion and changes in flow if possible.

From a pressure-guided to a perfusion-centered resuscitation strategy in septic shock: Critical literature review and illustrative case

PURPOSE

To support a paradigm shift in the management of septic shock from pressure-guided to perfusion-centered, expected to improve outcome while reducing adverse effects from vasopressor therapy and aggressive fluid resuscitation.

MATERIAL AND METHODS

Critical review of the literature cited in support of vasopressor use to achieve a predefined mean arterial pressure (MAP) of 65 mmHg and review of pertinent clinical trials and studies enabling deeper understanding of the hemodynamic pathophysiology supportive of a perfusion-centered approach, accompanied by an illustrative case.

RESULTS

Review of the literature cited by the Surviving Sepsis Campaign revealed lack of controlled clinical trials supporting outcome benefits from vasopressors. Additional literature review revealed adverse effects associated with vasopressors and worsened outcome in some studies. Vasopressors increase MAP primarily by peripheral vasoconstriction and in occasions by a modest increase in cardiac output when using norepinephrine. Thus, achieving the recommended MAP of 65 mmHg using vasopressors should not be presumed indicative that organ perfusion has been restored. It may instead create a false sense of hemodynamic stability hampering shock resolution.

CONCLUSIONS

We propose focusing the hemodynamic management of septic shock on reversing organ hypoperfusion instead of attaining a predefined MAP target as the key strategy for improving outcome.

Early Use of Norepinephrine Improves Survival in Septic Shock: Earlier than Early

BACKGROUND

The timing of initiation of Norepinephrine (NEP) in septic shock is controversial.

AIM OF THE STUDY

We evaluated the impact of early NEP simultaneously with fluids in those patients.

METHODS

We randomized 101 patients admitted to the emergency department with septic shock to early NEP simultaneously with IV fluids (early group) or after failed fluids trial (late group). The primary outcome was the in-hospital survival while the secondary outcomes were the time to target mean arterial pressure (MAP) of 65 mmHg, lactate clearance and resuscitation volumes.

RESULTS

There was no significant difference between the two groups regarding the baseline characteristics. NEP infusion started after 25 (20-30) and 120 (120-180) min in the early and late groups (p = 0.000). MAP of 65 mmHg was achieved faster in the early group (2 [1-3.5] h vs. 3 [2-4.75] h, p = 0.003). Serum lactate was decreased by 37.8 (24-49%) and 22.2 (3.3-38%) in both groups respectively (p = 0.005). Patients with early NEP were resuscitated by significantly lower volume of fluids (25 [18.8-28.7] mL/kg vs. 32.5 [24.4-34.6] mL/kg) in the early and late groups (p = 0.000). The early group had survival rate of 71.9% compared to 45.5% in the late group (p = 0.007). NEP started after 30 (20-120 min) in survivors vs. 120 (30-165 min) in non-survivors (p = 0.013).

CONCLUSIONS

We concluded that early Norepinephrine in septic shock might cause earlier restoration of blood pressure, better lactate clearance and improve in-hospital survival.

Blood pressure targets for vasopressor therapy: a systematic review

Physicians often prescribe vasopressors to correct pathological vasodilation and improve tissue perfusion in patients with septic shock, but the evidence to inform practice on vasopressor dosing is weak. We undertook a systematic review of clinical studies evaluating different blood pressure targets for the dosing of vasopressors in septic shock. We searched MEDLINE, EMBASE, CENTRAL (to November 2013), reference lists from included articles, and trial registries for randomized controlled trials (RCTs) and observational and crossover intervention studies comparing different blood pressure targets for vasopressor therapy in septic shock. Two reviewers independently selected eligible studies and extracted data on standardized forms. We identified 2 RCTs and 10 crossover trials but no observational studies meeting our criteria. Only one RCT measured clinical outcomes after comparing mean arterial pressure targets of 80 to 85 mmHg versus 65 to 70 mmHg. There was no effect on 28-day mortality, but confidence intervals were wide (hazard ratio, 95% confidence interval [95% CI] 0.84 - 1.38). In contrast, this intervention was associated with a greater risk of atrial fibrillation (relative risk, 2.36; 95% CI, 1.18 - 4.72) and a lower risk of renal replacement therapy in hypertensive patients (relative risk, 0.75; 95% CI, 0.57 - 1.0). Crossover trials suggest that achieving higher blood pressure targets by increasing vasopressor doses increases heart rate and cardiac index with no effect on serum lactate. Our findings underscore the paucity of clinical evidence to guide the administration of vasopressors in critically ill patients with septic shock. Further rigorous research is needed to establish an evidence base for vasopressor administration in this population.

Pressor Response to Noradrenaline in the Setting of Septic Shock: Anything New under the Sun-Dexmedetomidine, Clonidine? A Minireview

Progress over the last 50 years has led to a decline in mortality from ≈70% to ≈20% in the best series of patients with septic shock. Nevertheless, refractory septic shock still carries a mortality close to 100%. In the best series, the mortality appears related to multiple organ failure linked to comorbidities and/or an intense inflammatory response: shortening the period that the subject is exposed to circulatory instability may further lower mortality. Treatment aims at reestablishing circulation within a "central" compartment (i.e., brain, heart, and lung) but fails to reestablish a disorganized microcirculation or an adequate response to noradrenaline, the most widely used vasopressor. Indeed, steroids, nitric oxide synthase inhibitors, or donors have not achieved overwhelming acceptance in the setting of septic shock. Counterintuitively, α 2-adrenoceptor agonists were shown to reduce noradrenaline requirements in two cases of human septic shock. This has been replicated in rat and sheep models of sepsis. In addition, some data show that α 2-adrenoceptor agonists lead to an improvement in the microcirculation. Evidence-based documentation of the effects of alpha-2 agonists is needed in the setting of human septic shock.

[Adequate fluid resuscitation in septic shock with high catecholamine doses]

BACKGROUND

Appropriate fluid resuscitation is a fundamental aspect for the hemodynamic management of septic shock patients and should ideally be achieved before vasopressors and positive inotropic substances are administered. The development of hemodynamic monitoring has revealed that in some cases patients had been improperly treated with high-dose catecholamines for initially insufficient fluid resuscitation. The aim of this study was to show that in some cases it is possible to actively reduce catecholamines by a volume challenge adapted according to the individual patient needs.

MATERIAL AND METHODS

In this retrospective observational study 29 patients with septic shock in a surgical intensive care unit (ICU) at a university hospital (17 male, 12 female, mean age 71 ± 10 years) on high-dose catecholamines (median values norepinephrine 0.204 µg/kg body weight/min, dobutamine 3.876 µg/kg/min and epinephrine 0.025 µg/kg/min, ranging up to 0.810 µg/kg/min, 22.222 µg/kg/min and 0.407 µg/kg/min in 28, 20 and 17 patients, respectively) were analyzed. The extremities of the patients were initially cold with a mottled marbled appearance whereas the mean arterial pressure (MAP) was ≥ 65 mmHg. The median central venous pressure (CVP) was 17 mmHg (range 55-34 mmHg) and the mean lactate concentration was 2.78 mmol/l (range 0.93-10.67 mmol/l). The standard therapy concept consisted of a forced volume challenge combined with active reduction of catecholamines to achieve an adequate fluid loading status, guided by the passive leg raising test (PLR), clinical signs and in 19 cases by hemodynamic monitoring (pulmonary artery catheter Vigilance II(™) n = 10, FloTrac(™), Vigileo(™) n = 9 and PreSep(™) n = 5; Edwards Life Sciences). The forced volume challenge was stopped after clinical improvement with rewarmed extremities, increasing diuresis volumes and lack of improvement by PLR.

RESULTS

Catecholamine doses could be significantly reduced in all patients: norepinephrine to 0 µg/kg/min, dobutamine to 1.852 µg/kg/min and epinephrine to 0 µg/kg/min (up to 0.133 µg/kg/min, 6.289 µg/kg/min and 0.091 µg/kg/min, respectively, p < 0.05 Wilcoxon signed rank test). Volume challenge test: + 4,500 ml Ringer solution (range 0-24,000 ml) and 1,000 ml hydroxyethyl starch (range 0-2,500 ml) and mean fluid balance + 6,465 ml (range + 2,040 ml to + 27,255 ml). The median weaning time from catecholamines was 12 h (range 4-43 h). After treatment all patients showed rewarmed extremities and a decrease in mean lactate levels from 2.78 mmol/l (range 0.93-10.67 mmol/l) to 2.05 mmol/l (range 0.7-5.4 mmol/l). The measured hemodynamic constellations showed clear interindividual differences but no cardiac deterioration occurred. The median oxygenation index (paO2/FiO2) showed a statistically insignificant change from 264 mmHg (range 75-418 mmHg) to 250 mmHg (range 120-467 mmHg). Of the patients 20 survived and 9 died.

CONCLUSION

It is possible to wean a substantial proportion of septic shock patients from high-dose catecholamines in combination with a needs-adapted forced volume challenge test. The importance of appropriate fluid loading prior to the use of high catecholamine doses should be a main subject of discussion in patients with severe septic shock and was confirmed in this study. This should be oriented to clinical and if possible, hemodynamic parameters and should not be underestimated.

Empiric antimicrobial therapy in severe sepsis and septic shock: optimizing pathogen clearance

Mortality and morbidity in severe sepsis and septic shock remain high despite significant advances in critical care. Efforts to improve outcome in septic conditions have focused on targeted, quantitative resuscitation strategies utilizing intravenous fluids, vasopressors, inotropes, and blood transfusions to correct disease-associated circulatory dysfunction driven by immune-mediated systemic inflammation. This review explores an alternate paradigm of septic shock in which microbial burden is identified as the key driver of mortality and progression to irreversible shock. We propose that clinical outcomes in severe sepsis and septic shock hinge upon the optimized selection, dosing, and delivery of highly potent antimicrobial therapy.

The arterial blood pressure associated with terminal cardiovascular collapse in critically ill patients: a retrospective cohort study

Introduction

Liberal and overaggressive use of vasopressors during the initial period of shock resuscitation may compromise organ perfusion and worsen outcome. When transiently applying the concept of permissive hypotension, it would be helpful to know at which arterial blood pressure terminal cardiovascular collapse occurs.

Methods

In this retrospective cohort study, we aimed to identify the arterial blood pressure associated with terminal cardiovascular collapse in 140 patients who died in the intensive care unit while being invasively monitored. Demographic data, co-morbid conditions and clinical data at admission and during the 24 hours before and at the time of terminal cardiovascular collapse were collected. The systolic, mean and diastolic arterial blood pressures immediately before terminal cardiovascular collapse were documented. Terminal cardiovascular collapse was defined as an abrupt (<5 minutes) and exponential decrease in heart rate (>50% compared to preceding values) followed by cardiac arrest.

Results

The mean ± standard deviation (SD) values of the systolic, mean and diastolic arterial blood pressures associated with terminal cardiovascular collapse were 47 ± 12 mmHg, 35 ± 11 mmHg and 29 ± 9 mmHg, respectively. Patients with congestive heart failure (39 ± 13 mmHg versus 34 ± 10 mmHg; P = 0.04), left main stem stenosis (39 ± 11 mmHg versus 34 ± 11 mmHg; P = 0.03) or acute right heart failure (39 ± 13 mmHg versus 34 ± 10 mmHg; P = 0.03) had higher arterial blood pressures than patients without these risk factors. Patients with severe valvular aortic stenosis had the highest arterial blood pressures associated with terminal cardiovascular collapse (systolic, 60 ± 20 mmHg; mean, 46 ± 12 mmHg; diastolic, 36 ± 10 mmHg), but this difference was not significant. Patients with sepsis and patients exposed to sedatives or opioids during the terminal phase exhibited lower arterial blood pressures than patients without sepsis or administration of such drugs.

Conclusions

The arterial blood pressure associated with terminal cardiovascular collapse in critically ill patients was very low and varied with individual co-morbid conditions (for example, congestive heart failure, left main stem stenosis, severe valvular aortic stenosis, acute right heart failure), drug exposure (for example, sedatives or opioids) and the type of acute illness (for example, sepsis).

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0719-2) contains supplementary material, which is available to authorized users.

Early versus delayed administration of norepinephrine in patients with septic shock

INTRODUCTION

This study investigated the incidence of delayed norepinephrine administration following the onset of septic shock and its effect on hospital mortality.

METHODS

We conducted a retrospective cohort study using data from 213 adult septic shock patients treated at two general surgical intensive care units of a tertiary care hospital over a two year period. The primary outcome was 28-day mortality.

RESULTS

The 28-day mortality was 37.6% overall. Among the 213 patients, a strong relationship between delayed initial norepinephrine administration and 28-day mortality was noted. The average time to initial norepinephrine administration was 3.1 ± 2.5 hours. Every 1-hour delay in norepinephrine initiation during the first 6 hours after septic shock onset was associated with a 5.3% increase in mortality. Twenty-eight day mortality rates were significantly higher when norepinephrine administration was started more than or equal to 2 hours after septic shock onset (Late-NE) compared to less than 2 hours (Early-NE). Mean arterial pressures at 1, 2, 4, and 6 hours after septic shock onset were significantly higher and serum lactate levels at 2, 4, 6, and 8 hours were significantly lower in the Early-NE than the Late-NE group. The duration of hypotension and norepinephrine administration was significantly shorter and the quantity of norepinephrine administered in a 24-hour period was significantly less for the Early-NE group compared to the Late-NE group. The time to initial antimicrobial treatment was not significantly different between the Early-NE and Late-NE groups.

CONCLUSION

Our results show that early administration of norepinephrine in septic shock patients is associated with an increased survival rate.

Early versus delayed administration of norepinephrine in patients with septic shock

Introduction

This study investigated the incidence of delayed norepinephrine administration following the onset of septic shock and its effect on hospital mortality.

Methods

We conducted a retrospective cohort study using data from 213 adult septic shock patients treated at two general surgical intensive care units of a tertiary care hospital over a two year period. The primary outcome was 28-day mortality.

Results

The 28-day mortality was 37.6% overall. Among the 213 patients, a strong relationship between delayed initial norepinephrine administration and 28-day mortality was noted. The average time to initial norepinephrine administration was 3.1 ± 2.5 hours. Every 1-hour delay in norepinephrine initiation during the first 6 hours after septic shock onset was associated with a 5.3% increase in mortality. Twenty-eight day mortality rates were significantly higher when norepinephrine administration was started more than or equal to 2 hours after septic shock onset (Late-NE) compared to less than 2 hours (Early-NE). Mean arterial pressures at 1, 2, 4, and 6 hours after septic shock onset were significantly higher and serum lactate levels at 2, 4, 6, and 8 hours were significantly lower in the Early-NE than the Late-NE group. The duration of hypotension and norepinephrine administration was significantly shorter and the quantity of norepinephrine administered in a 24-hour period was significantly less for the Early-NE group compared to the Late-NE group. The time to initial antimicrobial treatment was not significantly different between the Early-NE and Late-NE groups.

Conclusion

Our results show that early administration of norepinephrine in septic shock patients is associated with an increased survival rate.

Timing of vasopressor initiation and mortality in septic shock: a cohort study

Introduction

Despite recent advances in the management of septic shock, mortality remains unacceptably high. Earlier initiation of key therapies including appropriate antimicrobials and fluid resuscitation appears to reduce the mortality in this condition. This study examined whether early initiation of vasopressor therapy is associated with improved survival in fluid therapy-refractory septic shock.

Methods

Utilizing a well-established database, relevant information including duration of time to vasopressor administration following the initial documentation of recurrent/persistent hypotension associated with septic shock was assessed in 8,670 adult patients from 28 ICUs in Canada, the United States of America, and Saudi Arabia. The primary endpoint was survival to hospital discharge. Secondary endpoints were length of ICU and hospital stay as well as duration of ventilator support and vasopressor dependence. Analysis involved multivariate linear and logistic regression analysis.

Results

In total, 8,640 patients met the definition of septic shock with time of vasopressor/inotropic initiation documented. Of these, 6,514 were suitable for analysis. The overall unadjusted hospital mortality rate was 53%. Independent mortality correlates included liver failure (odds ratio (OR) 3.46, 95% confidence interval (CI), 2.67 to 4.48), metastatic cancer (OR 1.63, CI, 1.32 to 2.01), AIDS (OR 1.91, CI, 1.29 to 2.49), hematologic malignancy (OR 1.88, CI, 1.46 to 2.41), neutropenia (OR 1.78, CI, 1.27 to 2.49) and chronic hypertension (OR 0.62 CI, 0.52 to 0.73). Delay of initiation of appropriate antimicrobial therapy (OR 1.07/hr, CI, 1.06 to 1.08), age (OR 1.03/yr, CI, 1.02 to 1.03), and Acute Physiology and Chronic Health Evaluation (APACHE) II Score (OR 1.11/point, CI, 1.10 to 1.12) were also found to be significant independent correlates of mortality. After adjustment, only a weak correlation between vasopressor delay and hospital mortality was found (adjusted OR 1.02/hr, 95% CI 1.01 to 1.03, P <0.001). This weak effect was entirely driven by the group of patients with the longest delays (>14.1 hours). There was no significant relationship of vasopressor initiation delay to duration of vasopressor therapy (P = 0.313) and only a trend to longer duration of ventilator support (P = 0.055) among survivors.

Conclusion

Marked delays in initiation of vasopressor/inotropic therapy are associated with a small increase in mortality risk in patients with septic shock.

An alternate pathophysiologic paradigm of sepsis and septic shock: implications for optimizing antimicrobial therapy

The advent of modern antimicrobial therapy following the discovery of penicillin during the 1940s yielded remarkable improvements in case fatality rate of serious infections including septic shock. Since then, pathogens have continuously evolved under selective antimicrobial pressure resulting in a lack of significant improvement in clinical effectiveness in the antimicrobial therapy of septic shock despite ever more broad-spectrum and potent drugs. In addition, although substantial effort and money has been expended on the development novel non-antimicrobial therapies of sepsis in the past 30 years, clinical progress in this regard has been limited. This review explores the possibility that the current pathophysiologic paradigm of septic shock fails to appropriately consider the primacy of the microbial burden of infection as the primary driver of septic organ dysfunction. An alternate paradigm is offered that suggests that has substantial implications for optimizing antimicrobial therapy in septic shock. This model of disease progression suggests the key to significant improvement in the outcome of septic shock may lie, in great part, with improvements in delivery of existing antimicrobials and other anti-infectious strategies. Recognition of the role of delays in administration of antimicrobial therapy in the poor outcomes of septic shock is central to this effort. However, therapeutic strategies that improve the degree of antimicrobial cidality likely also have a crucial role.

Re-thinking resuscitation: leaving blood pressure cosmetics behind and moving forward to permissive hypotension and a tissue perfusion-based approach

Definitions of shock and resuscitation endpoints traditionally focus on blood pressures and cardiac output. This carries a high risk of overemphasizing systemic hemodynamics at the cost of tissue perfusion. In line with novel shock definitions and evidence of the lack of a correlation between macro- and microcirculation in shock, we recommend that macrocirculatory resuscitation endpoints, particularly arterial and central venous pressure as well as cardiac output, be reconsidered. In this viewpoint article, we propose a three-step approach of resuscitation endpoints in shock of all origins. This approach targets only a minimum individual and context-sensitive mean arterial blood pressure (for example, 45 to 50 mm Hg) to preserve heart and brain perfusion. Further resuscitation is exclusively guided by endpoints of tissue perfusion irrespectively of the presence of arterial hypotension ('permissive hypotension'). Finally, optimization of individual tissue (for example, renal) perfusion is targeted. Prospective clinical studies are necessary to confirm the postulated benefits of targeting these resuscitation endpoints.

Prescribed targets for titration of vasopressors in septic shock: a retrospective cohort study

BACKGROUND

Without robust clinical evidence to guide titration of vasopressors in septic shock, it is unclear how dosing of these potent medications occurs. We sought to measure the proportion of vasopressor prescriptions for septic shock that were missing explicit targets and to describe the targets that we identified.

METHODS

We conducted a multicentre, retrospective cohort study involving 9 intensive care units (ICUs) located at 3 academic hospitals in Canada and Australia. We reviewed charts of consecutive patients aged 18 years or older who were admitted to the ICU for a presumptive diagnosis of sepsis. Other inclusion criteria were hypotension (systolic arterial pressure ≤ 90 mm Hg or mean arterial pressure [MAP] ≤ 65 mm Hg) and continuous infusion of vasopressors for at least 1 hour within the initial 48 hours of ICU stay, the period of observation for this study.

RESULTS

We included data from 369 patient charts. At least 1 target was specified in 99% of charts. The most common targets were MAP measurements (73%). The median initial MAP target was 65 (range 55-90) mm Hg. In multivariable regression models, hospital site and older age of the patient, but not comorbidities of the patient, were associated with MAP targets. In 40% of patients, the treating team modified the initial target at least once.

INTERPRETATION

This study suggests that an explicit blood pressure target accompanies nearly every vasopressor prescription and that patient characteristics have little influence on its value. Identification of a titration strategy that will maximize benefit and minimize harm constitutes a research priority.

High-dose norepinephrine treatment: determinants of mortality and futility in critically ill patients

BACKGROUND

Critically ill patients with circulatory shock sometimes need rescue treatment with high doses of norepinephrine, a treatment that may be associated with a poor outcome because of excessive vasoconstriction.

OBJECTIVE

To evaluate the outcome of treatment and its determinants in patients with circulatory shock who received high doses of norepinephrine in the intensive care unit and to identify indicators of futility for the treatment.

METHODS

A retrospective study was done on 113 consecutive patients with circulatory shock who received 0.9 μg/kg per minute or greater of norepinephrine during at least 1 hour at any time in the intensive care unit. Data were extracted from the electronic patient data management system according to a predefined checklist.

RESULTS

A total of 39 patients survived for 28 days after admission to the intensive care unit. The variables independently associated with 28-day mortality in multivariable models included low urine flow, high lactate levels, high organ failure score, high prothrombin time, and need for epinephrine cotreatment. The reason, dose, and duration of norepinephrine administration did not have prognostic significance. Scores greater than 40 on the Acute Physiology and Chronic Health Evaluation II, bicarbonate levels less than 9.0 mEq/L, or receipt of an epinephrine dose of 0.25 μg/kg per minute or greater were associated with 100% mortality.

CONCLUSIONS

Although the cause of shock and treatment with norepinephrine were not predictive of death when high doses of the drug were deemed necessary, rescue treatment with high-dose norepinephrine is futile in patients with severe disease and metabolic acidemia.

Early antimicrobial therapy in severe sepsis and septic shock

The advent of modern antimicrobial therapy following the discovery of penicillin during the 1940s yielded remarkable improvements in the case fatality rates of serious infections, including septic shock. Since then, pathogens have continuously evolved under selective antimicrobial pressure, resulting in a lack of additional significant improvement in clinical effectiveness of antimicrobial therapy of septic shock despite ever more broad-spectrum and potent drugs. In addition, although substantial effort and money were expended on the development of novel nonantimicrobial therapies of sepsis in the past 30 years, clinical progress in this regard has been limited. This article explores the possibility that the key to significant improvement in the outcome of septic shock may lie, in great part, with improvements in delivery of existing antimicrobials. Recognizing the role of delays in administration of antimicrobial therapy in the poor outcomes of septic shock is central to this effort.

Effects of methylene blue and volatile anesthetics on survival in a murine hemorrhage resuscitation model

BACKGROUND

Hemorrhage is a frequent cause of morbidity and mortality, possibly complicated by volatile anesthetics administered during surgical emergencies. Because methylene blue (MB) was suggested to reduce bleeding, we reasoned that it may improve resuscitation. We used a rat model of controlled and uncontrolled hemorrhage with fluid resuscitation, aiming at high versus low mean arterial pressure (MAP) to assess the role of early MB injection on survival and the effects of different anesthetics on outcome.

METHODS

Wistar male rats (n = 160) were subjected to 15-minute controlled and 60-minute uncontrolled hemorrhage and received lactated Ringer's solution replacement. Four sets (four groups per set, N = 10 per group) were anesthetized with halothane, isoflurane, sevoflurane, or ketamine (KET; control). Resuscitation-targeted MAP was 80 mm Hg in two groups per set and 40 mm Hg in two groups per set: one group received MB 25 mg/kg intravenously and the other one did not receive.

RESULTS

All parameters were worse in the higher target groups compared with the lower MAP target groups. MB improved variable outcomes in the treated compared with the nontreated groups, independent of the MAP or anesthesia agent: the amount of replacement volume, lung tissue xanthine oxidase activity, and rats' survival rates. Outcomes with and without MB were worse in the halothane set, followed, in ascending order, by sevoflurane, isoflurane, and KET.

CONCLUSIONS

MB improved parameters and survival rates after controlled and uncontrolled hemorrhage and fluid resuscitation, even in high MAP-resuscitated rats. KET seemed to be the best anesthetic choice among the four classic agents tested. The effects of balanced anesthesia and total intravenous anesthesia in similar conditions require additional studies.

Association of arterial blood pressure and vasopressor load with septic shock mortality: a post hoc analysis of a multicenter trial

Introduction

It is unclear to which level mean arterial blood pressure (MAP) should be increased during septic shock in order to improve outcome. In this study we investigated the association between MAP values of 70 mmHg or higher, vasopressor load, 28-day mortality and disease-related events in septic shock.

Methods

This is a post hoc analysis of data of the control group of a multicenter trial and includes 290 septic shock patients in whom a mean MAP ≥ 70 mmHg could be maintained during shock. Demographic and clinical data, MAP, vasopressor requirements during the shock period, disease-related events and 28-day mortality were documented. Logistic regression models adjusted for the geographic region of the study center, age, presence of chronic arterial hypertension, simplified acute physiology score (SAPS) II and the mean vasopressor load during the shock period was calculated to investigate the association between MAP or MAP quartiles ≥ 70 mmHg and mortality or the frequency and occurrence of disease-related events.

Results

There was no association between MAP or MAP quartiles and mortality or the occurrence of disease-related events. These associations were not influenced by age or pre-existent arterial hypertension (all P > 0.05). The mean vasopressor load was associated with mortality (relative risk (RR), 1.83; confidence interval (CI) 95%, 1.4-2.38; P < 0.001), the number of disease-related events (P < 0.001) and the occurrence of acute circulatory failure (RR, 1.64; CI 95%, 1.28-2.11; P < 0.001), metabolic acidosis (RR, 1.79; CI 95%, 1.38-2.32; P < 0.001), renal failure (RR, 1.49; CI 95%, 1.17-1.89; P = 0.001) and thrombocytopenia (RR, 1.33; CI 95%, 1.06-1.68; P = 0.01).

Conclusions

MAP levels of 70 mmHg or higher do not appear to be associated with improved survival in septic shock. Elevating MAP >70 mmHg by augmenting vasopressor dosages may increase mortality. Future trials are needed to identify the lowest acceptable MAP level to ensure tissue perfusion and avoid unnecessary high catecholamine infusions.