Lower versus higher blood pressure targets in comatose patients resuscitated from out-of-hospital cardiac arrest-Protocol for a secondary Bayesian analysis of the box trial

BACKGROUND

The management of blood pressure targets during intensive care after out-of-hospital cardiac arrest (OHCA) remains a topic of debate. The blood Pressure and Oxygenation Targets After OHCA (BOX) trial explored the efficacy of two different blood pressure targets in 789 patients during intensive care after OHCA. In the primary frequentist analysis, no statistically significant differences were found for neurological outcome after 90 days.

METHODS

This protocol outlines secondary Bayesian analyses of 365-day all-cause mortality and two secondary outcomes: neurological outcome after 365 days, and plasma neuron-specific enolase, a biomarker of brain injury, after 48 h. We will employ adjusted Bayesian logistic and linear regressions, presenting results as relative and absolute differences with 95% confidence intervals. We will use weakly informative priors for the primary analyses, and skeptical and evidence-based priors (where available) in sensitivity analyses. Exact probabilities for any benefit/harm will be presented for all outcomes, along with probabilities of clinically important benefit/harm (risk differences larger than 2%-points absolute) and no clinically important differences for the binary outcomes. We will assess whether heterogeneity of treatment effects on mortality is present according to lactate at admission, time to return of spontaneous circulation, primary shockable rhythm, age, hypertension, and presence of ST-elevation myocardial infarction.

DISCUSSION

This secondary analysis of the BOX trial aim to complement the primary frequentist analysis by quantifying the probabilities of beneficial or harmful effects of different blood pressure targets. This approach seeks to provide clearer insights for researchers and clinicians into the effectiveness of these blood pressure management strategies in acute medical conditions, particularly focusing on mortality, neurological outcomes, and neuron-specific enolase.

Use and Outcomes of Peripheral Vasopressors in Early Sepsis-Induced Hypotension Across Michigan Hospitals: A Retrospective Cohort Study

BACKGROUND

Vasopressors traditionally are administered via central access, but newer data suggest that peripheral administration may be safe and may avoid delays and complications associated with central line placement.

RESEARCH QUESTION

How commonly are vasopressors initiated through peripheral IV lines in routine practice? Is vasopressor initiation route associated with in-hospital mortality?

STUDY DESIGN AND METHODS

This retrospective cohort study included adults hospitalized with sepsis (November 2020-September 2022) at 29 hospitals in the Michigan Hospital Medicine Safety Consortium, a Collaborative Quality Initiative sponsored by Blue Cross Blue Shield of Michigan. We assessed route of early vasopressor initiation, factors and outcomes associated with peripheral initiation, and timing of central line placement.

RESULTS

Five hundred ninety-four patients received vasopressors within 6 h of hospital arrival and were included in this study. Peripheral vasopressor initiation was common (400/594 [67.3%]). Patients with peripheral vs central initiation were similar; BMI was the only patient factor associated independently with initiation route (adjusted OR [aOR] of peripheral initiation [per 1-kg/m2 increase], 0.98; 95% CI, 0.97-1.00; P = .015). The specific hospital showed a large impact on initiation route (median OR, 2.19; 95% CI, 1.31-3.07). Compared with central initiation, peripheral initiation was faster (median, 2.5 h vs 2.7 h from hospital arrival; P = .002), but was associated with less initial norepinephrine use (84.3% vs 96.8%; P = .001). We found no independent association between initiation route and in-hospital mortality (32.3% vs 42.2%; aOR, 0.66; 95% CI, 0.39-1.12). No tissue injury from peripheral vasopressors was documented. Of patients with peripheral initiation, 135 of 400 patients (33.8%) never received a central line.

INTERPRETATION

Peripheral vasopressor initiation was common across Michigan hospitals and had practical benefits, including expedited vasopressor administration and avoidance of central line placement in one-third of patients. However, the findings of wide practice variation that was not explained by patient case mix and lower use of first-line norepinephrine with peripheral administration suggest that additional standardization may be needed.

Safety of pre-hospital peripheral vasopressors: The SPOTLESS study (Safety of PrehOspiTaL pEripheral vaSopreSsors)

OBJECTIVE

To assess the safety and effectiveness of peripheral vasoactive drugs initiated during pre-hospital care and retrieval missions, in Queensland, Australia.

METHODS

Three years of retrospective data was gathered from two sources. Medical notes were reviewed using a search for any patient having 'inotrope' recorded on an electronic medical record. Each case was reviewed to include only peripheral infusions of adrenaline or noradrenaline. Clinical Governance records were searched for adverse events related to vasoactive drugs, alerted for review to ensure complete capture.

RESULTS

A total of 418 patients received peripheral infusions of adrenaline and noradrenaline over the 3-year period. No major complications were recorded either immediately or at Clinical Governance review. Minor complications were recorded in 4.7% of the cases, of which 3.5% occurred with peripheral vasoactives during the presence of the retrieval team. The frequency of use of peripheral vasoactives increased over the study period.

CONCLUSIONS

In this retrospective data set there were no major complications of peripheral vasoactive drugs. Minor complications were similar to in-hospital use and related to vascular access and drug delivery.

Exploring the Efficacy of Midodrine for Tapering Off Vasopressors

Sepsis and septic shock represent critical conditions, often necessitating vasopressor support in the intensive care unit (ICU). Midodrine, an oral vasopressor, has gathered attention as a potential adjunct to vasopressor therapy, aiming to facilitate weaning and improve clinical outcomes. However, the efficacy of midodrine remains questionable, with conflicting evidence from clinical trials and meta-analyses. This article provides a comprehensive review of the literature on midodrine's role in ICU settings by gathering evidence from multicenter trials, retrospective studies, and meta-analyses. While some studies suggest a limited benefit of midodrine in expediting vasopressor weaning and reducing ICU/hospital stays, others report potential advantages, particularly in reducing mortality rates among septic shock patients. Ongoing efforts aim to address knowledge gaps surrounding midodrine's efficacy and safety.

The effect of pituitrin on postoperative outcomes in patients with pulmonary hypertension undergoing cardiac surgery: a study protocol for a randomized controlled trial

Background

The vasoplegic syndrome is one of the major consequences of cardiac surgery. If pulmonary hypertension is additionally involved with vasoplegic syndrome, circulation management becomes much more complicated. According to previous studies, pituitrin (a substitute for vasopressin, which contains vasopressin and oxytocin) not only constricts systemic circulation vessels and increases systemic circulation pressure but also likely decreases pulmonary artery pressure and pulmonary vascular resistance. The aim of this study is to investigate whether pituitrin is beneficial for the postoperative outcomes in patients with pulmonary hypertension undergoing cardiac surgery.

Methods and analysis

The randomized controlled trial will include an intervention group continuously infused with 0.04 U/(kg h) of pituitrin and a control group. Adult patients with pulmonary hypertension undergoing elective cardiac surgery will be included in this study. Patients who meet the conditions and give their consent will be randomly assigned to the intervention group or the control group. The primary outcome is the composite endpoint of all-cause mortality within 30 days after surgery or common complications after cardiac surgery. Secondary outcomes include the incidence of other postoperative complications, length of hospital stay, and so on.

Discussion

Pituitrin constricts systemic circulation vessels, increases systemic circulation pressure, and may reduce pulmonary artery pressure and pulmonary vascular resistance, which makes it a potentially promising vasopressor during the perioperative period in patients with pulmonary hypertension. Therefore, evidence from randomized controlled trials is necessary to elucidate whether pituitrin influences outcomes in patients with pulmonary hypertension following cardiac surgery.

Droxidopa or Atomoxetine for Refractory Hypotension in Critically Ill Cardiothoracic Surgery Patients

OBJECTIVE

To evaluate the effects of droxidopa or atomoxetine on intravenous (IV) vasoactive agent discontinuation in cardiothoracic intensive care unit (ICU) patients with hypotension refractory to midodrine.

DESIGN

Single-center, retrospective cohort study.

SETTING

Tertiary- and quaternary-care university teaching hospital.

PARTICIPANTS

Included patients who received at least 4 consecutive doses of droxidopa or atomoxetine and remained on concurrent midodrine. Patients were excluded if they received study medication before admission, had clinical deterioration after study medication initiation requiring additional vasoactives/escalation of IV vasoactive dosage for at least 12 hours, had a diagnosis of hepatorenal syndrome, were prisoners, or were pregnant.

INTERVENTIONS

Droxidopa, atomoxetine, or both.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was time to discontinuation of IV vasoactive agents after initiation of study medication, analyzed using a Kaplan-Meier estimate with the Wilcoxon method, censoring death within 24 hours of the last dose of study medication. No adjustment for repetitive analyses was made, as the analysis was hypothesis-generating. Of the 72 charts reviewed, 45 patients met inclusion criteria (18 atomoxetine, 17 droxidopa, and 10 both). There were no differences in median time to discontinuation of IV vasoactive agents (21.9 days v 8.0 days v 13.9 days, respectively; p = 0.259) or ICU or hospital length of stay between groups. A higher percentage of patients who survived to hospital discharge received both study medications or droxidopa alone (90% v 76.5%) than atomoxetine alone (44.4%, p = 0.028).

CONCLUSIONS

Droxidopa and atomoxetine are oral vasoactive agents with potential mechanisms to facilitate IV vasopressor weaning for patients in the ICU with hypotension refractory to midodrine, but further prospective research is needed.

Diversifying cardiac intensive care unit models: Successful example of an operating surgeon-led unit

Objective

The intensivist-led cardiovascular intensive care unit model is the standard of care in cardiac surgery. This study examines whether a cardiovascular intensive care unit model that uses operating cardiac surgeons, cardiothoracic surgery residents, and advanced practice providers is associated with comparable outcomes.

Methods

This is a single-institution review of the first 400 cardiac surgery patients admitted to an operating surgeon-led cardiovascular intensive care unit from 2020 to 2022. Inclusion criteria are elective status and operations managed by both cardiovascular intensive care unit models (aortic operations, valve operations, coronary operations, septal myectomy). Patients from the surgeon-led cardiovascular intensive care unit were exact matched by operation type and 1:1 propensity score matched with controls from the traditional cardiovascular intensive care unit using a logistic regression model that included age, sex, preoperative mortality risk, incision type, and use of cardiopulmonary bypass and circulatory arrest. Primary outcome was total postoperative length of stay. Secondary outcomes included postoperative intensive care unit length of stay, 30-day mortality, 30-day Society of Thoracic Surgeons-defined morbidity (permanent stroke, renal failure, cardiac reoperation, prolonged intubation, deep sternal infection), packed red cell transfusions, and vasopressor use. Outcomes between the 2 groups were compared using chi-square, Fisher exact test, or 2-sample t test as appropriate.

Results

A total of 400 patients from the surgeon-led cardiovascular intensive care unit (mean age 61.2 ± 12.8 years, 131 female patients [33%], 346 patients [86.5%] with European System for Cardiac Operative Risk Evaluation II <2%) and their matched controls were included. The most common operations across both units were coronary artery bypass grafting (n = 318, 39.8%) and mitral valve repair or replacement (n = 238, 29.8%). Approximately half of the operations were performed via sternotomy (n = 462, 57.8%). There were 3 (0.2%) in-hospital deaths, and 47 patients (5.9%) had a 30-day complication. The total length of stay was significantly shorter for the surgeon-led cardiovascular intensive care unit patients (6.3 vs 7.0 days, P = .028), and intensive care unit length of stay trended in the same direction (2.5 vs 2.9 days, P = .16). Intensive care unit readmission rates, 30-day mortality, and 30-day morbidity were not significantly different between cardiovascular intensive care unit models. The surgeon-led cardiovascular intensive care unit was associated with fewer postoperative red blood cell transfusions in the cardiovascular intensive care unit (P = .002) and decreased vasopressor use (P = .001).

Conclusions

In its first 2 years, the surgeon-led cardiovascular intensive care unit demonstrated comparable outcomes to the traditional cardiovascular intensive care unit with significant improvements in total length of stay, postoperative transfusions in the cardiovascular intensive care unit, and vasopressor use. This early success exemplifies how an operating surgeon-led cardiovascular intensive care unit can provide similar outcomes to the standard-of-care model for patients undergoing elective cardiac surgery.

Intraoperative Versus Postoperative Hydroxocobalamin for Vasoplegic Shock in Cardiothoracic Surgery

OBJECTIVES

Hydroxocobalamin inhibits nitric oxide pathways contributing to vasoplegic shock in patients undergoing cardiopulmonary bypass (CPB). The objective of this study was to evaluate the effect of intraoperative versus postoperative application of hydroxocobalamin for vasoplegic shock in patients undergoing CPB.

DESIGN

This was a historic cohort study.

SETTING

The study was conducted at a quaternary academic cardiovascular surgery program.

PARTICIPANTS

Adults undergoing cardiac surgery using CPB were participants in the study.

INTERVENTIONS

Hydroxocobalamin (5 g) intravenously over 15 minutes.

MEASUREMENTS AND MAIN RESULTS

The treatment groups were assigned based on the receipt location of hydroxocobalamin (ie, intensive care unit [ICU] versus operating room [OR]). The primary outcome was vasopressor-free days in the first 14 days after CPB. Of the 112 patients included, 37 patients received hydroxocobalamin in the OR and 75 in the ICU. Patients in the OR group were younger than those in the ICU group (57.5 v 63.9 years, p = 0.007), with statistically similar American Society of Anesthesiologists scores. The mean CPB duration was 3.4 hours in the OR group and 2.9 hours in the ICU group (p = 0.09). In both groups, the norepinephrine-equivalent dose of vasopressors at hydroxocobalamin was 0.27 µg/kg/min. Days alive and free of vasopressors were not different between the OR and ICU groups (estimated difference 0.48 [95% CI -1.76-2.72], p = 0.67). The odds of postoperative renal failure, mesenteric ischemia, ICU, hospital length of stay, and in-hospital mortality were also similar between groups.

CONCLUSIONS

A difference in vasopressor-free days after CPB was not found between patients who received hydroxocobalamin intraoperatively versus postoperatively for vasoplegic shock.

Phenylephrine and norepinephrine increase blood pressure through opposing physiologic mechanisms in isoflurane-anesthetized dogs receiving acepromazine

OBJECTIVE

To elucidate the cardiovascular effects of escalating doses of phenylephrine and norepinephrine in dogs receiving acepromazine and isoflurane.

ANIMALS

8 beagles aged 1 to 2 years (7.4 to 11.2 kg).

METHODS

All dogs received acepromazine 0.01 mg/kg, propofol 4 to 5 mg/kg, and isoflurane and were mechanically ventilated. Mean arterial pressure (MAP) from a femoral artery catheter and continuous electrocardiogram were recorded. Cardiac output (CO) was measured with transpulmonary thermodilution. Systemic vascular resistance (SVR), global end-diastolic volume (GEDV), and global ejection fraction (GEF) were subsequently calculated. Phenylephrine and norepinephrine were infused in random order at 0.07, 0.3, 0.7, and 1.0 μg/kg/min. All variables were measured after 15 minutes of each infusion rate. The effects of dose, agent, and their interaction on the change of each variable were evaluated with mixed-effect models. A P < .05 was used for significance.

RESULTS

Atrial premature complexes occurred in 3 dogs during norepinephrine infusion at doses of 0.3, 0.7, and 1 μg/kg/min; no dysrhythmias were seen with phenylephrine administration. MAP increased during dose escalation (P < .0001) within each agent and did not differ between agents (P = .6). The decrease in HR was greater for phenylephrine (P < .0001). Phenylephrine decreased CO and GEF and increased GEDV and SVR (all P < .03). Norepinephrine decreased the SVR and increased CO, GEDV, and GEF (all P < .03).

CLINICAL RELEVANCE

Our results confirm that phenylephrine increases arterial pressures mainly through vasoconstriction in acepromazine-premedicated dogs while norepinephrine, historically considered a vasopressor, does so primarily through an increase in inotropism.

Intraoperative blood pressure: could less be more?

Retrospective observational studies have reported a significant association between intraoperative hypotension and postoperative morbidity. However, association does not imply causation, and whether preventing intraoperative hypotension can improve patient outcome remains to be demonstrated. In this issue of the British Journal of Anaesthesia, D'Amico and colleagues meta-analysed 10 prospective randomised trials comparing low (≤60 mm Hg) and higher mean arterial pressure targets during anaesthesia and surgery. They did not observe an increase in postoperative morbidity and mortality in the low target group. In contrast, they reported a statistically significant (but not clinically relevant) reduction in postoperative cardiac arrhythmia and hospital length of stay when targeting mean arterial pressure ≤60 mm Hg. These findings suggest that during most surgical cases, intraoperative hypotension is a marker of the severity, frailty, or both rather than a mediator of postoperative complications.

Trajectory of PaO2/FiO2 Ratio in Shock After Angiotensin II

INTRODUCTION

High-dose catecholamines can impair hypoxic pulmonary vasoconstriction and increase shunt fraction. We aimed to determine if Angiotensin II (Ang-2) is associated with improved PaO2/FiO2 and SpO2/FiO2 in patients in shock.

METHODS

Adult patients at four tertiary care centers and one community hospital in the United States who received Ang-2 from July 2018-September 2020 were included in this retrospective, observational cohort study. PaO2, SpO2, and FiO2 were measured at 13 timepoints during the 48-h before and after Ang-2 initiation. Piecewise linear mixed models of PaO2/FiO2 and SpO2/FiO2 were created to evaluate hourly changes in oxygenation after Ang-2 initiation. The difference in the proportion of patients with PaO2/FiO2 ≤ 300 mm Hg at the time of Ang-2 initiation and 48 h after was also examined.

RESULTS

The study included 254 patients. In the 48 h prior to Ang-2 initiation, oxygenation was significantly declining (hourly PaO2/FiO2 change -4.7 mm Hg/hr, 95% CI - 6.0 to -3.5, p < .001; hourly SpO2/FiO2 change -3.1/hr, 95% CI-3.7 to -2.4, p < .001). Ang-2 treatment was associated with significant improvements in PaO2/FiO2 and SpO2/FiO2 in the 48-h after initiation (hourly PaO2/FiO2 change +1.5 mm Hg/hr, 95% CI 0.5-2.5, p  =  .003; hourly SpO2/FiO2 change +0.9/hr, 95% CI 0.5-1.2, p < .001). The difference in the hourly change in oxygenation before and after Ang-2 initiation was also significant (pinteraction < 0.001 for both PaO2/FiO2 and SpO2/FiO2). This improvement was associated with significantly fewer patients having a PaO2/FiO2 ≤ 300 mm Hg at 48 h compared to baseline (mean difference -14.9%, 95% CI -25.3% to -4.6%, p  =  .011). Subgroup analysis found that patients with either a baseline PaO2/FiO2 ≤ 300 mm Hg or a norepinephrine-equivalent dose requirement >0.2 µg/kg/min had the greatest associations with oxygenation improvement.

CONCLUSIONS

Ang-2 is associated with improved PaO2/FiO2 and SpO2/FiO2. The mechanisms for this improvement are not entirely clear but may be due to catecholamine-sparing effect or may also be related to improved ventilation-perfusion matching, intrapulmonary shunt, or oxygen delivery.

Renin-angiotensin-aldosterone system dynamics after targeted blood pressure control using angiotensin II or norepinephrine in cardiac surgery: mechanistic randomised controlled trial

BACKGROUND

The role of the renin-angiotensin-aldosterone axis in vasoplegia after cardiac surgery remains unclear. We tested the hypothesis that, compared with norepinephrine, infusion of angiotensin II titrated to achieve similar mean arterial pressure (MAP) would suppress plasma renin concentration (PRC) while maintaining aldosterone levels.

METHODS

In a double-blind, randomised controlled trial, subjects received either an infusion of angiotensin II or norepinephrine to maintain MAP 70-80 mm Hg from induction of anaesthesia. We compared PRC, aldosterone, dipeptidyl peptidase-3, and angiotensin-converting enzyme 2 activity between treatment groups, before surgery, on ICU admission, and 24 h after surgery.

RESULTS

In 60 patients (11.7% female; mean age 68 yr [11 yr]), norepinephrine increased median PRC at ICU admission (median difference [MD] 46 [inter-quartile range, IQR, 3-88] μU ml-1; P<0.001) but angiotensin II did not (MD -3 [IQR -62 to 35] μU ml-1; P=0.36). Aldosterone levels increased with both. The aldosterone:PRC ratio did not change with norepinephrine (MD -0.01 [IQR -0.14 to 0.03] μU ml-1 per ng dl-1, P=0.76) but increased with angiotensin II (MD 0.05 [IQR 0.004-0.26] μU ml-1 per ng dl-1, P<0.001). The upper quartile of PRC before surgery was associated with higher vasopressor requirements when norepinephrine was used to maintain MAP, but not angiotensin II. Dipeptidyl peptidase-3 levels and angiotensin-converting enzyme 2 activities were similar at all time points.

CONCLUSIONS

Angiotensin II suppressed renin release while maintaining aldosterone levels compared with norepinephrine. Higher plasma renin concentration before surgery was associated with greater vasopressor requirement for norepinephrine, but not angiotensin II.

CLINICAL TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry-ACTRN12621000195853 23/02/2021.

The Development of Fat Embolism Syndrome (FES) and Multiple Small Pulmonary Emboli Following Open Reduction Internal Fixation (ORIF) of a Left Femur Fracture: A Case Report

Fat embolism syndrome (FES) is a rare but potentially life-threatening complication that can occur following orthopedic procedures, such as long bone fracture repairs. FES is caused by the release of fat globules into the bloodstream, leading to the obstruction of blood vessels and subsequent tissue damage. Pulmonary embolism (PE), a condition in which a blood clot travels to the lungs, is another potential complication of orthopedic procedures due to the mobilization of blood clots during surgery. We report the case of a 56-year-old female who presented to the emergency department with a left femur fracture following a mechanical fall and underwent open reduction internal fixation (ORIF) surgery for the fracture. The procedure was complicated by the development of FES and multiple small pulmonary emboli. The patient was managed postoperatively in the ICU, requiring support with multiple vasopressors and mechanical ventilation. She remained in the ICU for three days postoperatively and was discharged on postoperative day six to an inpatient rehabilitation facility.

Intraoperative arterial pressure management: knowns and unknowns

Preventing postoperative organ dysfunction is integral to the practice of anaesthesia. Although intraoperative hypotension is associated with postoperative end organ dysfunction, there remains ambiguity with regards to its definition, targets, thresholds for initiating treatment, and ideal treatment modalities.

Role of Inferior Vena Cava Collapsibility Index in the Prediction of Hypotension Associated With Central Neuraxial Block: A Prospective Observational Study

BACKGROUND

There are only a few studies on perioperative use of inferior vena cava collapsibility index (IVCCI) to predict hypotension after anesthesia. The study aimed to evaluate IVCCI as predictor of hypotension in patients receiving central neuraxial block (CNB) for elective surgery.

METHOD

One hundred patients of ASA grade I/II, aged 18-60 years undergoing elective surgery under CNB were enrolled. Ultrasound IVC examination was performed preoperatively and the patients were allocated to Group C (Collapsing group: IVCCI ≥50%) or Group NC (Non-Collapsing group: IVCCI <50%). Thereafter, in the operation theatre, the patient was given CNB and observed for development of hypotension. The hypotension was treated with additional fluid bolus (5 mL kg-1 over 10 minutes) and/or vasopressor (mephentramine 6 mg IV). The primary objective was to compare the incidence of hypotension; the secondary objective was to compare the fluid and vasopressor requirement in the Groups C and NC.

RESULT

Six patients were excluded from study due to poor visualization of IVC. The mean IVCCI for Group C (n = 53) was 56.06 ± 4.62% and Group NC (n = 41) was 34.01 ± 8.94%. The incidence of hypotension was 56.60% (20/53) in Group C and 4.87% (2/41) in Group NC (P < .001). The vasopressor and fluid requirement was also statistically significantly higher in Group C compared with Group NC (P < .001).

CONCLUSION

Preoperative ultrasound assessment of IVCCI is useful in predicting hypotension after CNB in patients receiving CNB for elective surgery.

A Comparison of Dobutamine, Norepinephrine, Vasopressin, and Hetastarch for the Treatment of Isoflurane-Induced Hypotension in Healthy, Normovolemic Dogs

Isoflurane is a commonly used inhalation anesthetic in species undergoing veterinary care that induces hypotension, impacting organ perfusion, making it imperative to minimize its occurrence or identify effective strategies for treating it. This study evaluated and compared the hemodynamic effects of DOB, NEP, VAS, and HES in twelve isoflurane-anesthetized Beagle dogs. The order of the first three treatments was randomized. HES was administered last. Data were collected before treatments (baseline) and after 10 min of a sustained MAP of <45 mmHg induced by a high end-tidal isoflurane concentration (T0). Once treatment was initiated and the target MAP was achieved (65 to 80 mmHg) or the maximum dose reached, data were collected after 15 min of stabilization (T1) and 15 min after (T2). A 15 min washout period with a MAP of ≥65 mmHg was allowed between treatments. The intravenous dosage regimens started and were increased by 50% every five minutes until the target MAP or maximum dose was reached. The dosages were as follows: DOB, 5-15 μg/kg/min; NEP, 0.1-2 μg/kg/min; VAS, 0.5-5 mU/kg/min; and HET, 6% 1-20 mL/kg/min. DOB improved CO, DO2, and VO2, but reduced SVR. VAS elevated SVR, but decreased CO, DO2, and VO2. HES minimally changed BP and mildly augmented CO, DO2, and VO2. These treatments failed to reach the target MAP. NEP increased the arterial BP, CO, MPAP, and PAWP, but reduced HR. Norepinephrine infusion at 0.44 ± 0.19 μg/kg/min was the most efficient therapy for correcting isoflurane-induced hypotension.

The Effect of Fluid Pre-loading on Vital Signs and Hemodynamic Parameters in a Porcine Model of Lipopolysaccharide-Induced Endotoxemia

Background Animal models of distributive hypotension and resuscitation allow the assessment of hemodynamic monitoring modalities and resuscitation strategies. The fluid-first paradigm for resuscitation is currently being challenged with clinical trials. In this investigation, venous return and perfusion are assessed, and full hemodynamics are characterized, in a porcine model of endotoxemic hypotension with and without fluid pre-loading. Methods Two groups of six pigs had the induction of standardized endotoxemic hypotension ("critical hypotension"). Group 1 underwent four 10 cc/kg crystalloid boluses, and Group 2 was not fluid pre-resuscitated. Both groups underwent progressive norepinephrine (NE) up-titration to 0.25 mcg/kg/minute over 30 minutes. Vital signs, central parameters, and laboratory values were obtained at baseline, "critical hypotension," after each bolus and during NE administration. Results Endotoxemia decreased the systemic vascular resistance (SVR) in Group 1 (1031±106 dyn/s/cm-5 versus 738±258 dyn/s/cm-5; P=0.03) and Group 2 (1121±196 dyn/s/cm-5 versus 759±342 dyn/s/cm-5; P=0.003). In Group 1, the four fluid boluses decreased heart rate (HR), pulmonary capillary wedge pressure (PCWP), and central venous pressure (CVP) (P<0.05). No changes were observed in blood pressure, cardiac output (CO), or lactate. NE up-titration increased HR in Group 1 and decreased CVP in both groups. Higher final CVP (11 {3} versus 4 {4} mmHg; P=0.01) and PCWP (5 {1} versus 2 {2} mmHg; P=0.005) values were observed in Group 1 relative to Group 2, reflecting increased venous return. Conclusions Porcine endotoxemic hypotension and resuscitation were robustly characterized. In this model, fluid loading improved venous return with NE, though perfusion (CO) was preserved by increased NE-induced chronotropy.

State of Shock: Contemporary Vasopressor and Inotrope Use in Cardiogenic Shock

Cardiogenic shock is characterized by tissue hypoxia caused by circulatory failure arising from inadequate cardiac output. In addition to treating the pathologic process causing impaired cardiac function, prompt hemodynamic support is essential to reduce the risk of developing multiorgan dysfunction and to preserve cellular metabolism. Pharmacologic therapy with the use of vasopressors and inotropes is a key component of this treatment strategy, improving perfusion by increasing cardiac output, altering systemic vascular resistance, or both, while allowing time and hemodynamic stability to treat the underlying disease process implicated in the development of cardiogenic shock. Despite the use of mechanical circulatory support recently garnering significant interest, pharmacologic hemodynamic support remains a cornerstone of cardiogenic shock management, with over 90% of patients receiving at least 1 vasoactive agent. This review aims to describe the pharmacology and hemodynamic effects of current pharmacotherapies and provide a practical approach to their use, while highlighting important future research directions.

Evaluation of Electrical Cardiometry for Measuring Cardiac Output and Derived Hemodynamic Variables in Comparison with Lithium Dilution in Anesthetized Dogs

Numerous cardiac output (CO) technologies were developed to replace the 'gold standard' pulmonary artery thermodilution due to its invasiveness and the risks associated with it. Minimally invasive lithium dilution (LiD) shows excellent agreement with thermodilution and can be used as a reference standard in animals. This study evaluated CO via noninvasive electrical cardiometry (EC) and acquired hemodynamic variables against CO measured using LiD in six healthy, anesthetized dogs administered different treatments (dobutamine, esmolol, phenylephrine, and high-dose isoflurane) impacting CO values. These treatments were chosen to cause drastic variations in CO, so that fair comparisons between EC and LiD across a wide range of CO values (low, intermediate, and high) could be made. Statistical analysis included linear regression, Bland-Altman plots, Lin's concordance correlation coefficient (ρ_c), and polar plots. Values of p < 0.05 represented significance. Good agreement was observed between EC and LiD, but consistent underestimation was noted when the CO values were high. The good trending ability, ρ_c of 0.88, and low percentage error of ±31% signified EC's favorable performance. Other EC-acquired variables successfully tracked changes in CO measured using LiD. EC may be a pivotal hemodynamic tool for continuously monitoring circulatory changes, as well as guiding and treating cardiovascular anesthetic complications in clinical settings.

Fluids and Early Vasopressors in the Management of Septic Shock: Do We Have the Right Answers Yet?

Septic shock is a common condition associated with hypotension and organ dysfunction. It is associated with high mortality rates of up to 60% despite the best recommended resuscitation strategies in international guidelines. Patients with septic shock generally have a Mean Arterial Pressure below 65 mmHg and hypotension is the most important determinant of mortality among this group of patients. The extent and duration of hypotension are important. The two initial options that we have are 1) administration of intravenous (IV) fluids and 2) vasopressors, The current recommendation of the Surviving Sepsis Campaign guidelines to administer 30 ml/kg fluid cannot be applied to all patients. Complications of fluid over-resuscitation further delay organ recovery, prolong ICU and hospital length of stay, and increase mortality. The only reason for administering intravenous fluids in a patient with circulatory shock is to increase the mean systemic filling pressure in a patient who is volume-responsive, such that cardiac output also increases. The use of vasopressors seems to be a more appropriate strategy, the very early administration of vasopressors, preferably during the first hour after diagnosis of septic shock, may have a multimodal action and potential advantages, leading to lower morbidity and mortality in the management of septic patients. Vasopressor therapy should be initiated as soon as possible in patients with septic shock.

Phenotyping cardiogenic shock that showed different clinical outcomes and responses to vasopressor use: a latent profile analysis from MIMIC-IV database

Background

Cardiogenic shock (CS) is increasingly recognized as heterogeneous in its severity and response to therapies. This study aimed to identify CS phenotypes and their responses to the use of vasopressors.

Method

The current study included patients with CS complicating acute myocardial infarction (AMI) at the time of admission from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Laboratory and clinical variables were collected and used to conduct latent profile (LPA) analysis. Furthermore, we used a multivariable logistic regression (LR) model to explore the independent association between the use of vasopressors and endpoints.

Result

A total of 630 eligible patients with CS after AMI were enrolled in the study. The LPA identified three profiles of CS: profile 1 (n = 259, 37.5%) was considered as the baseline group; profile 2 (n = 261, 37.8%) was characterized by advanced age, more comorbidities, and worse renal function; and profile 3 (n = 170, 24.6%) was characterized by systemic inflammatory response syndrome (SIRS)-related indexes and acid-base balance disturbance. Profile 3 showed the highest all-cause in-hospital mortality rate (45.9%), followed by profile 2 (43.3%), and profile 1 (16.6%). The LR analyses showed that the phenotype of CS was an independent prognostic factor for outcomes, and profiles 2 and 3 were significantly associated with a higher risk of in-hospital mortality (profile 2: odds ratio [OR] 3.95, 95% confidence interval [CI] 2.61-5.97, p < 0.001; profile 3: OR 3.90, 95%CI 2.48-6.13, p < 0.001) compared with profile 1. Vasopressor use was associated with an improved risk of in-hospital mortality for profile 2 (OR: 2.03, 95% CI: 1.15-3.60, p = 0.015) and profile 3 (OR: 2.91, 95% CI: 1.02-8.32, p = 0.047), respectively. The results of vasopressor use showed no significance for profile 1.

Conclusion

Three phenotypes of CS were identified, which showed different outcomes and responses to vasopressor use.

Vasopressor Effect of Indigo Carmine in the Management of Refractory Neurogenic Shock

Neurogenic shock in patients with spinal cord injuries can be fatal. Catecholamines are commonly used for the management of neurogenic shock; however, the treatment of catecholamine-refractory neurogenic shock remains challenging. A 78-year-old woman with neurogenic shock from cervical cord injury underwent posterior cervical spine decompression and fixation. The patient's blood pressure could not be maintained with catecholamine administration throughout the surgery. Therefore, indigo carmine was administered, and an effective increase in blood pressure was achieved. The postoperative course was uneventful. The findings from this case indicate that indigo carmine may have an effective vasoconstrictive action in patients with neurogenic shock who do not respond to catecholamines.

Vitamin C and thiamine for the treatment of refractory septic shock in surgical critically ill patients: a retrospective before-and-after study

OBJECTIVE

This study aimed to evaluate whether early vitamin C and thiamine administration was associated with a lower 28-day and in-hospital mortality in surgical critically ill patients with refractory septic shock.

METHODS

We performed a retrospective before-and-after study on patients with refractory septic shock. According to local protocol, hydrocortisone is initiated in case of refractory septic shock. In January 2017, the protocol was changed and vitamin C and thiamine were included. Patients who were admitted in 2015-2016 and 2017-2018 were included in the control and treatment groups, respectively. The primary end point was 28-day and in-hospital mortality. Secondary end points were ICU mortality, ICU and hospital length of stay, duration of vasopressors and mechanical ventilation, use of renal replacement therapy (RRT), and the modification in serum procalcitonin and SOFA score during the first 72 h.

RESULTS

A total of 120 patients were included (58 in the treatment group and 62 in the control group). Log-rank test in Kaplan-Meier curves showed lower 28-day and in-hospital mortality over time in the treatment group (p=0.021 and p=0.035, respectively) but it not reached statistical significance in ICU mortality over time (p=0.100). The need of RRT was less frequent in treatment group (17.2% vs. 37.1%, p=0.024). There were no differences in other secondary outcomes.

CONCLUSIONS

Intravenous vitamin C and thiamine administration in surgical patients with refractory septic shock may be associated with a lower 28-day and in-hospital mortality. Further prospective studies are needed in refractory septic shock.

Norepinephrine versus phenylephrine for treating hypotension during general anaesthesia in adult patients undergoing major noncardiac surgery: a multicentre, open-label, cluster-randomised, crossover, feasibility, and pilot trial

BACKGROUND

Intraoperative hypotension is associated with postoperative complications. The use of vasopressors is often required to correct hypotension but the best vasopressor is unknown.

METHODS

A multicentre, cluster-randomised, crossover, feasibility and pilot trial was conducted across five hospitals in California. Phenylephrine (PE) vs norepinephrine (NE) infusion as the first-line vasopressor in patients under general anaesthesia alternated monthly at each hospital for 6 months. The primary endpoint was first-line vasopressor administration compliance of 80% or higher. Secondary endpoints were acute kidney injury (AKI), 30-day mortality, myocardial injury after noncardiac surgery (MINS), hospital length of stay, and rehospitalisation within 30 days.

RESULTS

A total of 3626 patients were enrolled over 6 months; 1809 patients were randomised in the NE group, 1817 in the PE group. Overall, 88.2% received the assigned first-line vasopressor. No drug infiltrations requiring treatment were reported in either group. Patients were median 63 yr old, 50% female, and 58% white. Randomisation in the NE group vs PE group did not reduce readmission within 30 days (adjusted odds ratio=0.92; 95% confidence interval, 0.6-1.39), 30-day mortality (1.01; 0.48-2.09), AKI (1.1; 0.92-1.31), or MINS (1.63; 0.84-3.16).

CONCLUSIONS

A large and diverse population undergoing major surgery under general anaesthesia was successfully enrolled and randomised to receive NE or PE infusion. This pilot and feasibility trial was not powered for adverse postoperative outcomes and a follow-up multicentre effectiveness trial is planned.

CLINICAL TRIAL REGISTRATION

NCT04789330 (ClinicalTrials.gov).

Outcomes of perioperative vasopressor use for hemodynamic management of patients undergoing free flap surgery: A systematic review and meta-analysis

This systematic review and meta-analysis investigates the objective evidence regarding outcomes in head and neck free flap surgeries using vasoactive agents in the perioperative period. A search was performed in PubMed, Cochrane, Web of Science, and Scopus databases. Inclusion criteria were clinical studies in which vasopressors were used in head and neck free flap surgery during the intraoperative and perioperative period. Eighteen studies (n = 5397) were included in the qualitative analysis and nine (n = 4381) in the meta-analysis. There was no difference in flap failure outcomes with perioperative vasopressor use in head and neck free flap surgery (n = 4015, OR = 0.93, 95% CI [0.60, 1.44]). When patients received vasopressors perioperatively, there was an associated decrease in flap-specific complications (n = 3881, OR = 0.69, 95% CI [0.55, 0.87]). Intraoperative vasopressor use does not negatively impact free tissue transfer outcomes in head and neck surgery and may reduce overall free flap complications.

Norepinephrine and Vasopressin in Hemorrhagic Shock: A Focus on Renal Hemodynamics

During hemorrhagic shock, blood loss causes a fall in blood pressure, decreases cardiac output, and, consequently, O₂ transport. The current guidelines recommend the administration of vasopressors in addition to fluids to maintain arterial pressure when life-threatening hypotension occurs in order to prevent the risk of organ failure, especially acute kidney injury. However, different vasopressors exert variable effects on the kidney, depending on the nature and dose of the substance chosen as follows: Norepinephrine increases mean arterial pressure both via its α-1-mediated vasoconstriction leading to increased systemic vascular resistance and its β1-related increase in cardiac output. Vasopressin, through activation of V1-a receptors, induces vasoconstriction, thus increasing mean arterial pressure. In addition, these vasopressors have the following different effects on renal hemodynamics: Norepinephrine constricts both the afferent and efferent arterioles, whereas vasopressin exerts its vasoconstrictor properties mainly on the efferent arteriole. Therefore, this narrative review discusses the current knowledge of the renal hemodynamic effects of norepinephrine and vasopressin during hemorrhagic shock.

Norepinephrine May Exacerbate Septic Acute Kidney Injury: A Narrative Review

Sepsis, the most serious complication of infection, occurs when a cascade of potentially life-threatening inflammatory responses is triggered. Potentially life-threatening septic shock is a complication of sepsis that occurs when hemodynamic instability occurs. Septic shock may cause organ failure, most commonly involving the kidneys. The pathophysiology and hemodynamic mechanisms of acute kidney injury in the case of sepsis or septic shock remain to be elucidated, but previous studies have suggested multiple possible mechanisms or the interplay of multiple mechanisms. Norepinephrine is used as the first-line vasopressor in the management of septic shock. Studies have reported different hemodynamic effects of norepinephrine on renal circulation, with some suggesting that it could possibly exacerbate acute kidney injury caused by septic shock. This narrative review briefly covers the updates on sepsis and septic shock regarding definitions, statistics, diagnosis, and management, with an explanation of the putative pathophysiological mechanisms and hemodynamic changes, as well as updated evidence. Sepsis-associated acute kidney injury remains a major burden on the healthcare system. This review aims to improve the real-world clinical understanding of the possible adverse outcomes of norepinephrine use in sepsis-associated acute kidney injury.

How Effective is Angiotensin II in Decreasing Mortality of Vasodilatory Shock? A Systematic Review

Background

Patients with severe vasodilation accompanied by refractory hypotension despite high doses of vasopressors were associated with a high mortality rate. The Ang-2 for the Treatment of High-Output Shock (ATHOS) 3 trial demonstrated that angiotensin 2 (Ang-2) could effectively increase MAP and blood pressure in vasodilatory shock patients. This systematic review aims to summarize the impact of Ang-2 for the treatment of vasodilatory shock on clinical outcomes, including length of stay, MAP level (before and after), and mortality also Ang-2 dose needed.

Methods

A systematic search in PubMed, Sage, ScienceDirect, Scopus and Gray literature was conducted to obtain studies about the use of Ang-2 in vasodilatory shock patients.

Results

In all of the studies that we obtained, there were different results regarding mortality in patients with vasodilatory shock with Ang-2. Mortality was significantly lower when Ang-2 was administered to patients with elevated renin. The initial dose of Ang-2 can be started at 10-20 ng/kg/min, but there is no agreement on the maximum dose. Ang-2 may be considered a third-line vasopressor if the targeted MAP has not been achieved after administration of norepinephrine >200 ng/kg/min for more than 6 hours. Although not statistically significant, the use of Ang-2 can reduce the length of stay in the ICU and in the hospital when compared to patients without Ang-2 therapy, in addition to reducing the dose of vasopressor.

Conclusion

Overall, the use of Ang-2 has potential to be a regimen for patients with vasodilatory shock. Further study is needed to obtain more data.

ST-Segment Elevation Myocardial Infarction on the Line: Inadvertent Arterial Infusion of Vasopressors Causing Acute Myocardial Infarction

Central venous catheters (CVCs), regarded as lines of life, are helpful in hemodynamic monitoring and delivering medications to patients. However, there are several complications that can result from the placement of CVCs. This includes accidental arterial puncture, which has a temporal association with hemorrhage, hematoma, and stroke. Infusion of vasopressors through such a mispositioned arterial CVC further increases the risk of these complications with potential end-organ ischemia. Here, we discuss the case of a 76-year-old woman who developed a myocardial infarction, heart failure, and subarachnoid hemorrhage following the arterial infusion of vasopressors through a malpositioned CVC.

Use of vasoactive agents in non-cardiac surgery: Protocol for a scoping review

BACKGROUND

An increasing number of patients undergo surgical procedures worldwide each year, and despite advances in quality and care, morbidity and mortality rates remain high. Perioperative hypotension is a well-described condition, and is associated with adverse outcomes. Both fluids and vasoactive agents are commonly used to treat hypotension, however, whether one vasoactive agent is preferable over another has yet to be explored.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement, we plan to conduct a scoping review of studies assessing the use of vasoactive agents in patients undergoing non-cardiac surgery. We will provide an overview of indications, agents used and outcomes assessed. We will assess and report the certainty of evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We will provide descriptive analyses of the included studies accompanied by tabulated results.

CONCLUSION

The outlined scoping review will provide a summary of the body of evidence on the use of vasoactive agents in the non-cardiac surgical population.

Effect of Esmolol on Clinical Outcomes in Critically Ill Patients: Data from the MIMIC-IV Database

BACKGROUND AND AIMS

Esmolol is a common short-acting drug to control ventricular rate. This study aimed to evaluate the association between use of esmolol and mortality in critically ill patients.

METHODS

This is a retrospective cohort study from MIMIC-IV database containing adult patients with a heart rate of over 100 beats/min during the intensive care unit (ICU) stay. Multivariable Cox proportional hazard models and logistic regression were used to explore the association between esmolol and mortality and adjust confounders. A 1:1 nearest neighbor propensity score matching (PSM) was performed to minimize potential cofounding bias. The comparison for secondary outcomes was performed at different points of time using an independent t-test.

RESULTS

A total of 30,332 patients were reviewed and identified as critically ill. There was no significant difference in 28-day mortality between two groups before (HR = 0.90, 95% CI = 0.73-1.12, p = 0.343) and after PSM (HR = 0.84, 95% CI = 0.65-1.08, p = 0.167). Similar results were shown in 90-day mortality before (HR = 0.93, 95% CI = 0.75-1.14, p = 0.484) and after PSM (HR = 0.85, 95% CI = 0.67-1.09, p = 0.193). However, esmolol treatment was associated with higher requirement of vasopressor use before (HR = 2.89, 95% CI = 2.18-3.82, p < 0.001) and after PSM (HR = 2.66, 95% CI = 2.06-3.45, p < 0.001). Esmolol treatment statistically reduced diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (all p < 0.001) and increased fluid balance at 24 hours (p < 0.05) but did not significantly lower SBP (p = 0.721). Patients in esmolol group showed no significant difference in lactate levels and daily urine output when compared with those in non-esmolol group when adjusted for confounders (all p > 0.05).

CONCLUSION

Esmolol treatment was associated with reduced heart rate and lowered DBP and MAP, which may increase vasopressor use and fluid balance at the timepoint of 24 hours in critically ill patients during ICU stay. However, after adjusting for confounders, esmolol treatment was not associated with 28-day and 90-day mortality.

Relationship Between Mean Arterial Pressure and Furosemide Stress Test Success Rates: A Retrospective Cohort Study

BACKGROUND

The furosemide stress test (FST) is a safe and easy assessment of renal tubular function. Other factors, such as mean arterial pressure (MAP), which may influence the success rates of the FST, have not been well defined.

OBJECTIVE

To evaluate the relationship between MAP and success rates of the FST in critically ill patients.

METHODS

Retrospective, single-center, institutional review board (IRB)-approved cohort study. Critically ill adult patients given at least one dose of intravenous (IV) furosemide (≥1-1.5 mg/kg) were included. Primary outcome was whether a MAP ≥ 75 mm Hg would equate to a higher FST success rate. Secondary outcome was the success rates of patient on one or more vasopressors.

RESULTS

Of 225 patients, 88 (39.1%) had a successful FST. In patients with a MAP ≥ 75 mm Hg, 60 out of 104 (57.7%) had a successful FST compared to 28 out of 121 (23.1%) of patients who had a MAP < 75 mm Hg (odds ratio [OR], 4.53, 95% CI, 2.55-8.74, P < 0.001). Patients on vasopressors at the time of the furosemide dose had lower rates of success compared to those not on vasoactive agents (30.4% versus 68.2%, p = 0.026). Limitations of this study include its retrospective design and reliance on documented urine output.

CONCLUSION AND RELEVANCE

Patients with a MAP ≥ 75 mm Hg were significantly more likely to have a successful FST compared to those with a MAP < 75 mm Hg. This represents the first report of factors that may influence FST success rates.

Early versus delayed vasopressor administration in patients with septic shock

Aim

This study aimed to investigate the association of early vasopressor initiation with improved septic shock outcomes.

Methods

This multicenter observational study was conducted in 17 intensive care units in Japan and included adult patients with sepsis admitted to the intensive care unit from July 2019 to August 2020 and treated with vasopressor therapy. Patients were divided into the early vasopressor group (≤1 h from sepsis recognition) and the delayed vasopressor group (>1 h). The impact of early vasopressor administration on risk-adjusted in-hospital mortality was estimated using logistic regression analyses adjusted by an inverse probability of treatment weighting analysis with propensity scoring.

Results

Among the 97 patients, 67 received vasopressor therapy within 1 h from sepsis recognition and 30 received vasopressor after 1 h. In-hospital mortality was 32.8% in the early vasopressor group and 26.7% in the delayed vasopressor group (p = 0.543). The adjusted odds ratio for in-hospital mortality was 0.76 (95% confidence interval 0.17-3.29) when comparing patients in the early vasopressor with those in the delayed vasopressor group. The fit curve from the mixed-effects model showed a relatively lower trend toward an infusion volume over time in the early vasopressor group than in the delayed vasopressor group.

Conclusion

Our study did not reach a definitive conclusion for early vasopressor administration. However, early vasopressor administration may help avoid volume overload in the long course of sepsis care.

Management of Vasopressor-Induced Acute Limb Ischemia (VIALI) in Septic Shock

Vasopressors used in critically ill patients with refractory shock poses a serious risk of non-occlusive peripheral limb ischemia leading to tissue necrosis and amputation. Acute limb ischemia is associated with high morbidity and mortality. Evidence-based medical literature is scarce on the prevention and management of vasopressor-induced acute limb ischemia (VIALI). Despite being a well-known and frequent complication of vasopressors, there is no standardized guideline for the prevention and management of vasopressor-induced limb ischemia. Vasopressors are required for the management of refractory shock which is defined as hypotension not responsive to intravenous fluid resuscitation alone. Distributive shock, which includes septic shock, causes inadequate tissue perfusion in adjunct with vasopressor use and is the most common cause of non-occlusive peripheral limb ischemia. This case study will focus on how early recognition and prompt treatment of VIALI are crucial in minimizing tissue necrosis and preventing amputations. We present a case of a middle-aged woman who developed distributive shock from sepsis of a urinary source secondary to obstructive uropathy (ureteral calculi). She presented with refractory shock and continued to remain in shock while undergoing emergent rigid cystoscopy with the placement of a ureteral stent. Despite adequate volume resuscitation, she required high doses of vasopressors resulting in peripheral extremity ischemia and necrosis of all her fingers and toes. By promptly initiating mitigation and preventive management strategies, we succeeded in minimizing tissue ischemia and reducing morbidity resulting from iatrogenic vasopressor-induced peripheral non-occlusive ischemia. These strategies include but are not limited to external warming of bilateral lower extremities, nitroglycerin paste application over the entire extremity, arterial assist pump, and low-dose therapeutic anticoagulation. The novel use of the arterial pump in acutely ischemic lower extremities likely helped salvage the toes which appeared to be at high risk of amputation.

Angiotensin II - A Brief Review and Role in Severe SARS-COV-2 Sepsis

The renin-angiotensin-aldosterone system (RAAS), whose major vasopressor effector is angiotensin II (ATII), has multiple activities and regulates sodium-water homeostasis and fluid and blood pressure homeostasis. RAAS plays a crucial role in cardiocirculatory shock because it counteracts hypotension and hypovolemia by activating different physiologic responses. Based on the encouraging results of the ATHOS-3 trial, the US Food and Drug Administration and the European Medicines Agency approved the use of ATII for catecholamine-resistant vasodilatory shock. More recently, ATII was used for the compassionate treatment of critically ill patients with COVID-19. Beyond its vasopressor properties, ATII was hypothesized to have antiviral activity because it induces internalization and degradation of angiotensin-converting enzyme 2 receptors used by SARS-Cov-2 to infect cells. Overall, the use of ATII in patients with COVID-19 showed promising results because its administration was associated with the achievement and maintenance of target mean arterial pressure, increased P_aO₂/F_IO₂ ratio, and decreased F_IO₂. The aim of this narrative review is to summarize the available knowledge on the use of ATII in patients with COVID-19.

Comparison of Heart Rate After Phenylephrine vs Norepinephrine Initiation in Patients With Septic Shock and Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is a common complication of sepsis. It is unclear whether norepinephrine, an α- and β-agonist, and phenylephrine, an α-agonist, are associated with different heart rates among patients with sepsis and AF.

RESEARCH QUESTION

Among patients with sepsis and AF, what is the difference in heart rate after phenylephrine initiation vs norepinephrine initiation?

STUDY DESIGN AND METHODS

With the use of an extensive database, we identified patients with sepsis and AF at the time of norepinephrine or phenylephrine initiation. We estimated the difference in heart rate between patients who received phenylephrine or norepinephrine 1 and 6 h after vasopressor initiation with the use of multivariable-adjusted linear regression, tested for effect modification by heart rate, and stratified by baseline heart rate ≥ 110 or < 110 beats/min. Secondary outcomes included conversion to sinus rhythm, bradycardia, vasopressor duration, ICU and hospital length of stay, and hospital death. Exploratory analyses were adjusted for practices that occurred after vasopressor initiation; sensitivity analyses used interrupted time series to estimate the difference in average heart rate between patients who received phenylephrine or norepinephrine.

RESULTS

Among 1847 patients with sepsis and AF, 946 patients (51%) received norepinephrine, and 901 patients (49%) received phenylephrine. After multivariable adjustment, phenylephrine was associated with a lower heart rate at 1 h (-4 beats/min; 95% CI, -6 to -1; P < .001) and 6 h (-4 beats/min; 95% CI, -6 to -1; P = .004). Higher heart rate before vasopressor administration was associated with larger heart rate reduction in patients who received phenylephrine compared with norepinephrine. There were no differences in secondary outcomes. Results were similar in exploratory and sensitivity analyses.

INTERPRETATION

In patients with sepsis and AF, the initiation of phenylephrine was associated with modestly lower heart rate compared with norepinephrine. Heart rate at vasopressor initiation appeared to be an important effect modifier. Whether modest reductions in heart rate are associated with clinical outcomes requires further study.

Fluids, vasopressors, and acute kidney injury after major abdominal surgery between 2015 and 2019: a multicentre retrospective analysis

BACKGROUND

Practice patterns related to intraoperative fluid administration and vasopressor use have potentially evolved over recent years. However, the extent of such changes and their association with perioperative outcomes, such as the development of acute kidney injury (AKI), have not been studied.

METHODS

We performed a retrospective analysis of major abdominal surgeries in adults across 26 US hospitals between 2015 and 2019. The primary outcome was AKI as defined by the Kidney Disease Improving Global Outcomes definition (KDIGO) using only serum creatinine criteria. Univariable linear predictive additive models were used to describe the dose-dependent risk of AKI given fluid administration or vasopressor use.

RESULTS

Over the study period, we observed a decrease in the volume of crystalloid administered, a decrease in the proportion of patients receiving more than 10 ml kg^-1 h^-1 of crystalloid, an increase in the amount of norepinephrine equivalents administered, and a decreased duration of hypotension. The incidence of AKI increased between 2016 and 2019. An increase of crystalloid administration from 1 to 10 ml kg^-1 h^-1 was associated with a 58% decreased risk of AKI.

CONCLUSIONS

Despite decreased duration of hypotension during the study period, decreased fluid administration and increased vasopressor use were associated with increased incidence of AKI. Crystalloid administration below 10 ml kg^-1 h^-1 was associated with an increased risk of AKI. Although no causality can be concluded, these data suggest that prevention and treatment of hypotension during abdominal surgery with liberal use of vasopressors at the expense of fluid administration is associated with an increased risk of postoperative AKI.

PRospective REgistry of PAtients in REfractory cardiogenic shock-The PREPARE CardShock registry

Aim

Cardiogenic shock (CS) is a hemodynamically complex multisystem syndrome associated with persistently high morbidity and mortality. As CS is characterized by progressive failure to provide adequate systemic perfusion, supporting end‐organ perfusion using mechanical circulatory support (MCS) seems intriguing. Since most patients with CS present in the catheterization laboratory, percutaneously implantable systems have the widest adoption in the field. We evaluated feasibility, outcomes, and complications after the introduction of a full‐percutaneous program for both the Impella CP device and venoarterial extracorporeal membrane oxygenator (VA‐ECMO).

Methods

PREPARE CardShock (PRospective REgistry of PAtients in REfractory cardiogenic shock) is a prospective single‐center registry, including 248 consecutive patients between May 2019 and April 2021, who underwent cardiac catheterization and displayed advanced cardiogenic shock. The median age was 70 (58–77) years and 28% were female. Sixty‐five percent of the cases had cardiac arrest, of which 66% were out‐of‐hospital cardiac arrest. A local standard operating procedure (SOP) indicating indications as well as relative and absolute contraindications for different means of MCS (Impella CP or VA‐ECMO) was used to guide MCS use. The primary endpoint was in‐hospital death and secondary endpoints were spontaneous myocardial infarction and major bleedings during the hospital stay.

Results

Overall mortality was 50.4% with a median survival of 2 (0–6) days. Significant independent predictors of mortality were cardiac arrest during the index event (odds ratio [OR] with 95% confidence interval [CI]: 2.53 [1.43–4.51]; p = 0.001), age > 65 years (OR: 2.05 [1.03–4.09]; p = 0.036]), pH < 7.30 (OR: 2.69 [1.56–4.66]; p < 0.001), and lactate levels > 2 mmol/L (OR: 4.51 [2.37–8.65]; p < 0.001).

Conclusions

Conclusive SOPs assist target‐orientated MCS use in CS. This study provides guidance on the implementation, validation, and modification of newly established MCS programs to aid centers that are establishing such programs.

[Mahuang (herbaceous stem of Ephedra spp.): chemistry, pharmacodynamics, and pharmacokinetics]

The Chinese medicinal herb Mahuang is herbaceous stem of Ephedra sinica, E. intermedia, or E. equisetina(Family, Ephedraceae). In China, Mahuang has been used, all the way over a millennium, as a key component herb of many herbal medicines for management of epidemics of acute respiratory illness and is also used in officially recommended herbal medicines for COVID-19. Mahuang is the first-line medicinal herb for cold and wheezing and also an effective diuretic herb for edema. However, Mahuang can also exert significant adverse effects. The key to safety and effectiveness is rational and precise use of the herb. In this review article, we comprehensively summarize chemical composition of Mahuang and associated differences in pharmacognosy, pharmacodynamics and pharmacokinetics of Mahuang compounds, along with the adverse effects of Mahuang compounds and products. Based on full understanding of how Mahuang is used in Chinese traditional medicine, systematic research on Mahuang in line with contemporary standards of pharmaceutical sciences will facilitate promoting Chinese herbal medicines to become more efficient in management of epidemic illnesses, such as COVID-19. To this end, we recommend research on Mahuang of two aspects, i.e., pharmacological investigation for its multicompound-involved therapeutic effects and toxicological investigation for clinical manifestation of the adverse effects, chemicals responsible for the adverse effects, and conditions for safe use of the herb and the herb-containing medicines.

Copeptin Release in Arterial Hypotension and Its Association with Severity of Disease in Critically Ill Children

Low copeptin levels may indicate inadequate arginine-vasopressin release promoting arterial hypotension, whereas high copeptin concentrations may reflect disease severity. This single-center prospective non-randomized clinical trial analyzed the course of blood copeptin in critically ill normo- and hypotensive children and its association with disease severity. In 164 patients (median age 0.5 years (interquartile range 0.1, 2.9)), the mean copeptin concentration at baseline was 43.5 pmol/L. Though not significantly different after 61 h (primary outcome, mean individual change: −12%, p = 0.36, paired t-test), we detected 1.47-fold higher copeptin concentrations during arterial hypotension when compared to normotension (mixed-effect ANOVA, p = 0.01). In total, 8 out of 34 patients (23.5%) with low copeptin concentrations <10 pmol/L were hypotensive. Copeptin was highest in the adjusted mixed-effect regression analysis within the first day (+20% at 14 h) and decreased significantly at 108 h (−27%) compared to baseline (p = 0.002). Moreover, we found a significant association with vasopressor-inotrope treatment intensity, infancy (1−12 months) and cardiopulmonary bypass (all p ≤ 0.001). In conclusion, high copeptin values were associated with arterial hypotension and severity of disease in critically ill children. This study does not support the hypothesis that low copeptin values might be indicative of arginine-vasopressin deficiency.

Methylene Blue Reduces Fluid Loading and Norepinephrine Requirements for Post-Resuscitation Syndrome in a Pig Model of Refractory Cardiac Arrest Resuscitated with Veno-Arterial ECMO

BACKGROUND

Refractory cardiac arrest management relies on extracorporeal cardiopulmonary resuscitation (ECPR), requiring the use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Circulatory flow recovery can be associated with an ischemia-reperfusion injury, leading to vasoplegia and vasopressor requirement. The aim of this work was to evaluate the impact on hemodynamics of a methylene blue bolus infusion in a porcine model of ischemic refractory cardiac arrest.

METHODS

Ischemic refractory cardiac arrest was induced in 20 pigs. After a low flow period of 30 min, VA-ECMO was initiated and the pigs were randomly assigned to the standard care group (norepinephrine + crystalloids) or methylene blue group (IV 2 mg·kg-1 bolus of methylene blue over 30 min + norepinephrine and crystalloids). Macrocirculatory parameters and lactate clearance were measured. Sublingual microcirculation was evaluated with sidestream dark field (SDF) imaging. The severity of the ischemic digestive lesions was assessed according to the histologic Chiu/Park scale.

RESULTS

Eighteen pigs were included. The total crystalloid load (5000 (6000-8000) mL vs. 17,000 (10,000-19,000) mL, p = 0.007, methylene blue vs. standard care group) and catecholamine requirements (0.31 (0.14-0.44) μg·kg-1·min-1 vs. 2.32 (1.17-5.55) μg·kg-1·min-1, methylene blue vs. standard care group, p = 0.004) were significantly reduced in the methylene blue group. There were no significant between-group differences in lactate clearance, sublingual capillary microvascular parameters assessed by SDF or histologic Chiu/Park scale.

CONCLUSIONS

In our refractory cardiac arrest porcine model treated with ECPR, methylene blue markedly reduced fluid loading and norepinephrine requirements in comparison to standard care during the first 6 h of VA-ECMO.

A Multicenter Observational Cohort Study of Angiotensin II in Shock

INTRODUCTION

Angiotensin II (Ang-2) is a non-catecholamine vasopressor that targets the renin-angiotensin-aldosterone system by agonism of the angiotensin type 1 receptor. Its utility as a vasopressor and a catecholamine-sparing agent was demonstrated in the pivotal ATHOS-3 trial, and numerous post-hoc analyses have shown reduced mortality in certain subsets of the population.

METHODS

Consecutive adult patients at 5 centers who received Ang-2 from 2017-2020 were included in this multicenter, retrospective observational cohort study. Patient demographics, hemodynamics, and adverse events were collected. The primary outcomes of the study were the mean difference in MAP and norepinephrine (NEpi)-equivalent dose at hours 0 and 3 following initiation of Ang-2 therapy.

RESULTS

One hundred and sixty-two patients were included in this study. The primary outcomes of an increase in MAP (mean difference 9.3 mmHg, 95% CI 6.4-12.1, p < 0.001) and a reduction in NEpi equivalent dose (mean difference 0.16 µg/kg/min, 95% CI 0.10-0.22, p < 0.001) between hours 0 and 3 were statistically significant. The median time to reach a MAP ≥65 was 16 minutes (IQR 5-60 min). After stratifying patients by the NED dose and number of vasopressors administered prior to the initiation of Ang-2, those with a NED dose < 0.2 µg/kg/min, NED dose < 0.3 µg/kg/min, or those on ≤ 3 vasopressors had a significantly greater reduction in NED by hour 3 than those patients above these thresholds.

CONCLUSION

Ang-2 is an effective vasopressor and reduces catecholamine dose significantly. Its effect is rapid, with target MAP obtained within 30 minutes in most patients. Given the critical importance of adequate blood pressure to organ perfusion, Ang-2 should be considered when target MAP cannot be achieved with conventional vasopressors. Ang-2 should be utilized early in the course of shock, before the NED dose exceeds 0.2-0.3 µg/kg/min and before the initiation of the fourth-line vasopressor.

Oral Water Has Cardiovascular Effects Up to 60 min in Shock Patients

Aim: Little is known about the cardiovascular effects of oral water intake in shock patients. This study was designed to assess the effect of oral water on stroke volume and blood pressure during a 1-h time period. Method and Results: This open-label, randomized clinical trial included patients admitted to intensive care with acute circulatory failure. Three ICU units at the anesthesia and critical care department of the Dijon Bourgogne University Hospital. Patients were randomized 1:1 to an intervention or standard care group. The intervention group received 500 ml of oral water while the standard care group received intravenous administration of 500 ml of physiological saline solution. Baseline SV did not differ between the two groups (36 ml [28;51] vs. 38 ml [30;51], p = 0.952). The number of patients who were fluid responders did not differ between the two groups [n = 19 (76%) vs. n = 18 (72%), p = 1]. The median change in stroke volume during the three time points did not differ between the two groups (p < 0.05). In the intervention group, blood pressure increased up to 60 min. In the control group, blood pressure quickly increased at the end of fluid expansion, then returned close to baseline value at 60 min. Conclusion: Shock patients who were administered oral water experienced improvements in blood pressure and blood flow up to 60 min when compared with patients who received intravenous saline solution. Further studies are warranted to confirm these effects. Clinical Trial Registration: www.clinicaltrials.gov, identifier: NCT03951519.

Antihypertensive Medications Prior to Shock Onset Do Not Impact Initial Vasopressor Requirements in Patients With Shock

Purpose: The effect of the use of antihypertensive agents in patients prior to the development of shock is unclear. The purpose of this study was to determine the impact of antihypertensive agents on vasopressor dose and duration in shock. Materials and Methods: This retrospective, single-center study included patients with shock who received at least one vasopressor for at least 24 hours after shock onset from January 1 to June 30, 2017. Patients taking an antihypertensive agent(s) were compared to those who were not. The primary outcome was the number of vasopressor-free hours at 72 hours. Secondary outcomes included maximum and cumulative vasopressor doses, intensive care unit length of stay, and 30-day mortality. Results: One hundred and sixty-eight patients were included and 99 (59%) were on antihypertensives. Distributive shock was the most common type of shock (75.5%) and more patients taking antihypertensives had hypertension, coronary artery disease, and dyslipidemia at baseline. There was no difference in the number of vasopressor-free hours at 72 hours between patients taking an antihypertensive medication(s) and the control group (2 hours vs 1 hour; P = .11). No difference was found between any of the secondary outcomes. Conclusion: Patients taking antihypertensive agents prior to shock onset did not require increased vasopressor doses or duration.

Is the Sympathetic System Detrimental in the Setting of Septic Shock, with Antihypertensive Agents as a Counterintuitive Approach? A Clinical Proposition

Mortality in the setting of septic shock varies between 20% and 100%. Refractory septic shock leads to early circulatory failure and carries the worst prognosis. The pathophysiology is poorly understood despite studies of the microcirculatory defects and the immuno-paralysis. The acute circulatory distress is treated with volume expansion, administration of vasopressors (usually noradrenaline: NA), and inotropes. Ventilation and anti-infectious strategy shall not be discussed here. When circulation is considered, the literature is segregated between interventions directed to the systemic circulation vs. interventions directed to the micro-circulation. Our thesis is that, after stabilization of the acute cardioventilatory distress, the prolonged sympathetic hyperactivity is detrimental in the setting of septic shock. Our hypothesis is that the sympathetic hyperactivity observed in septic shock being normalized towards baseline activity will improve the microcirculation by recoupling the capillaries and the systemic circulation. Therefore, counterintuitively, antihypertensive agents such as beta-blockers or alpha-2 adrenergic agonists (clonidine, dexmedetomidine) are useful. They would reduce the noradrenaline requirements. Adjuncts (vitamins, steroids, NO donors/inhibitors, etc.) proposed to normalize the sepsis-evoked vasodilation are not reviewed. This itemized approach (systemic vs. microcirculation) requires physiological and epidemiological studies to look for reduced mortality.

Cardiovascular Effects of Epinephrine During Experimental Hypothermia (32°C) With Spontaneous Circulation in an Intact Porcine Model

Aims: Rewarming from accidental hypothermia and therapeutic temperature management could be complicated by cardiac dysfunction. Although pharmacologic support is often applied when rewarming these patients, updated treatment recommendations are lacking. There is an underlying deficiency of clinical and experimental data to support such interventions and this prevents the development of clinical guidelines. Accordingly, we explored the clinical effects of epinephrine during hypothermic conditions.

Materials and methods: Anesthetized pigs were immersion cooled to 32°C. Predetermined variables were compared at temperature/time-point baseline, after receiving 30 ng/kg/min and 90 ng/kg/min epinephrine infusions: (1) before and during hypothermia at 32°C, and after rewarming to 38°C (n = 7) and (2) a time-matched (5 h) normothermic control group (n = 5).

Results: At 32°C, both stroke volume and cardiac output were elevated after 30 ng/kg/min administration, while systemic vascular resistance was reduced after 90 ng/kg/min. Epinephrine infusion did not alter blood flow in observed organs, except small intestine flow, and global O₂ extraction rate was significantly reduced in response to 90 ng/kg/min infusion. Electrocardiographic measurements were unaffected by epinephrine infusion.

Conclusion: Administration of both 30 ng/kg/min and 90 ng/kg/min at 32°C had a positive inotropic effect and reduced afterload. We found no evidence of increased pro-arrhythmic activity after epinephrine infusion in hypothermic pigs. Our experiment therefore suggests that β₁-receptor stimulation with epinephrine could be a favorable strategy for providing cardiovascular support in hypothermic patients, at core temperatures >32°C.

Vasopressor-Induced Digital Ischemia

In patients who are critically ill and in circulatory shock, substantial dosages of vasopressors including norepinephrine and Neosynephrine are often required to sustain blood pressure. While these medications are necessary and can be lifesaving, they are often associated with several complications related to severe vasoconstrictions. One of these known but underreported side effects is digital ischemia (DI). DI refers to a decrease in digital perfusion. It is a rare and uncommon phenomenon that can lead to significant consequences and unfortunately can result in amputation of the digits. Herein, we report an unfortunate female with septic shock secondary to acute bowel ischemia who developed bilateral digital necrosis while on norepinephrine.

Vasoactive pharmacologic therapy in cardiogenic shock: a critical review

Background

Cardiogenic shock (CS) is an acute complex condition leading to morbidity and mortality. Vasoactive medications, such as vasopressors and inotropes are considered the cornerstone of pharmacological treatment of CS to improve end-organ perfusion by increasing cardiac output (CO) and blood pressure (BP), thus preventing multiorgan failure.

Objective

A critical review was conducted to analyze the currently available randomized studies of vasoactive agents in CS to determine the indications of each agent and to critically appraise the methodological quality of the studies.

Methods

PubMed database search was conducted to identify randomized controlled trials (RCTs) on vasoactive therapy in CS. After study selection, the internal validity of the selected studies was critically appraised using the three-item Jadad scale.

Results

Nine studies randomized 2388 patients with a mean age ranged between 62 and 69 years, were identified. Seven of studies investigated CS in the setting of acute myocardial infarction (AMI). The studies evaluated the comparisons of norepinephrine (NE) vs. dopamine, epinephrine vs. NE, levosimendan vs. dobutamine, enoximone or placebo, and nitric oxide synthase inhibitors (NOSi) vs. placebo. The mean Jadad score of the nine studies was 3.33, with only three studies of a score of 5.

Conclusions

The evidence from the studies of vasoactive agents in CS carries uncertainties. The methodological quality between the studies is variable due to the inherent difficulties to conduct a study in CS. Vasopressors and inotropes continue to have a fundamental role given the lack of pharmacological alternatives.