Pharmacologic agents for acute hemodynamic instability: recent advances in the management of perioperative shock- a systematic review

Running from a Bear: How We Teach Vasopressors, Adrenoreceptors, and Shock

Vasopressors are widely used in the management of shock among critically ill patients. The physiology of vasopressors and adrenoreceptors and their effects on end organs therefore represent important, high-yield topics for learners in the critical care environment. In this report, we describe our approach to teaching this core concept using the stereotypical human physiologic response when running from a bear, in the context of the relevant supporting literature. We use escaping from a threatening predator as a lens to describe the end-organ effects of activating adrenoreceptors together with the effects of endogenous and exogenous catecholamines and vasopressors. After reviewing this foundational physiology, we transition to the clinical environment, reviewing the pathophysiology of various shock states. We then consolidate our teaching by integrating the physiology of adrenoreceptors with the pathophysiology of shock to understand the appropriateness of each therapy to various shock phenotypes. We emphasize to learners the importance of generating a hypothesis about a patient's physiology, testing that hypothesis with an intervention, and then revising the hypothesis as needed, a critical component in the management of critically ill patients.

Hemodynamic impact of early mobilization in critical patients receiving vasoactive drugs: A prospective cohort study

BACKGROUND

Vasoactive drugs are one of the most common patient-related barriers to early mobilization. Little is known about the hemodynamic effects of early mobilization on patients receiving vasoactive drugs. This study aims to observe and describe the impact of mobilization on the vital signs of critical patients receiving vasoactive drugs as well as the occurrence of adverse events.

METHODS

This is a cohort study performed in an Intensive Care Unit with patients receiving vasoactive drugs. All patients, either mobilized or non-mobilized, had their clinical data such as vital signs [heart rate, respiratory rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and oxygen saturation], type and dosage of the vasoactive drug, and respiratory support collected at rest. For mobilized patients, the vital signs were also collected after mobilization, and so was the highest level of mobility achieved and the occurrence of adverse events. The criteria involved in the decision of mobilizing the patients were registered.

RESULTS

53 patients were included in this study and 222 physiotherapy sessions were monitored. In most of the sessions (n = 150, 67.6%), patients were mobilized despite the use of vasoactive drugs. There was a statistically significant increase in heart rate and respiratory rate after mobilization when compared to rest (p<0.05). Only two (1.3%) out of 150 mobilizations presented an adverse event. Most of the time, non-mobilizations were justified by the existence of a clinical contraindication (n = 61, 84.7%).

CONCLUSIONS

The alterations observed in the vital signs of mobilized patients may have reflected physiological adjustments of patients' cardiovascular and respiratory systems to the increase in physical demand imposed by the early mobilization. The adverse events were rare, not serious, and reversed through actions such as a minimal increase of the vasoactive drug dosage.

Improving nutrition practices for postoperative high-risk heart transplant and ventricular assist device implant patients in circulatory compromise: A quality improvement pre- and post-protocol intervention outcome study

BACKGROUND

Patients undergoing heart transplant (HT) and ventricular assist device (VAD) implant may experience intra- and postoperative complications requiring high-dose vasopressor agents and/or mechanical circulatory support. These complications increase the risk of nonocclusive bowel ischemia (NOBI) and inadequate enteral nutrition (EN) delivery, and guidance for this high-risk patient population is limited. To optimize nutrition support practices in this patient population at our institution, we created the High-Risk Nutrition Support Protocol (HRNSP) to improve nutrient delivery and promote safer EN practices in the setting of NOBI risk factors after HT and VAD implant.

METHODS

We developed and implemented a nutrition support protocol as a quality improvement (QI) initiative. Data were obtained before (n = 62) and after (n = 52) protocol initiation. We compared nutrition and clinical outcomes between the pre- and post-intervention groups.

RESULTS

Fewer calorie deficits (P < 0.001), fewer protein deficits (P < 0.001), a greater proportion of calorie/protein needs met (P < 0.001), zero NOBI cases (0%), and decreased intensive care unit (ICU) length of stay (LOS) (P = 0.005) were observed with 100% (n = 52 of 54) HRNSP implementation success. Increased use of parenteral nutrition did not increase central line-associated bloodstream infections (P = 0.46). There was no difference in hospital LOS (P = 0.44) or 90-day and 1-year mortality (P = 0.56, P = 0.35).

CONCLUSION

This single-center, QI pre- and post-protocol intervention outcome study suggests that implementing and adhering to a nutrition support protocol for VAD implant/HT patients with hemodynamic complications increases nutrient delivery and is associated with reduced ICU LOS and NOBI.

Detection of Hemodynamic Status Using an Analytic Based on an Electrocardiogram Lead Waveform

OBJECTIVES

Delayed identification of hemodynamic deterioration remains a persistent issue for in-hospital patient care. Clinicians continue to rely on vital signs associated with tachycardia and hypotension to identify hemodynamically unstable patients. A novel, noninvasive technology, the Analytic for Hemodynamic Instability (AHI), uses only the continuous electrocardiogram (ECG) signal from a typical hospital multiparameter telemetry monitor to monitor hemodynamics. The intent of this study was to determine if AHI is able to predict hemodynamic instability without the need for continuous direct measurement of blood pressure.

DESIGN

Retrospective cohort study.

SETTING

Single quaternary care academic health system in Michigan.

PATIENTS

Hospitalized adult patients between November 2019 and February 2020 undergoing continuous ECG and intra-arterial blood pressure monitoring in an intensive care setting.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One million two hundred fifty-two thousand seven hundred forty-two 5-minute windows of the analytic output were analyzed from 597 consecutive adult patients. AHI outputs were compared with vital sign indications of hemodynamic instability (heart rate > 100 beats/min, systolic blood pressure < 90 mm Hg, and shock index of > 1) in the same window. The observed sensitivity and specificity of AHI were 96.9% and 79.0%, respectively, with an area under the curve (AUC) of 0.90 for heart rate and systolic blood pressure. For the shock index analysis, AHI's sensitivity was 72.0% and specificity was 80.3% with an AUC of 0.81.

CONCLUSIONS

The AHI-derived hemodynamic status appropriately detected the various gold standard indications of hemodynamic instability (hypotension, tachycardia and hypotension, and shock index > 1). AHI may provide continuous dynamic hemodynamic monitoring capabilities in patients who traditionally have intermittent static vital sign measurements.

Trends of vasopressor use in intensive care units in Colombia

Introduction: Vasopressors are essential in the management of various types of shock. Objective: To establish the trend of vasopressors use in the intensive care units (ICU) in a population of patients affiliated with the Colombian Health System, 2010-2017. Methods: Observational trial using a population database of patients hospitalized in eleven ICUs in various cities in Colombia. The drugs dispensed to hospitalized patients over 18 years old, from January 2010 until December 2017 were considered. A review and analysis of the vasopressors dispensed per month was conducted, taking into account sociodemographic and pharmacological variables (vasopressor used and daily doses defined per 100/beds/day (DBD). Results: 81,348 dispensations of vasopressors, equivalent to 26,414 treatments in 19,186 patients receiving care in 11 hospitals from 7 cities were reviewed. The mean age of patients was 66.3±18.1 years and 52.6 % were males. Of the total number of treatments recorded, 17,658 (66.8 %) were with just one vasopressor. Norepinephrine was the most frequently prescribed drug (75.9 % of the prescriptions dispensed; 60.5 DBD), followed by adrenaline (26.6 %; 41.6 DBD), dopamine (19.4%), dobutamine (16.0 %), vasopressin (8.5 %) and phenylephrine (0.9 %). The use of norepinephrine increased from 2010 to 2017 (+6.19 DBD), whilst the use of other drugs decreased, particularly the use of adrenaline (-60.6 DBD) and dopamine (-10.8 DBD). Conclusions: Norepinephrine is the most widely used vasopressor showing a growing trend in terms of its use during the study period, which is supported by evidence in favor of its effectiveness and safety in patients with shock.

Meta-analysis of α-blockade versus no blockade before adrenalectomy for phaeochromocytoma

BACKGROUND

Preoperative α-blockade in phaeochromocytoma surgery is recommended by all guidelines to prevent intraoperative cardiocirculatory events. The aim of this meta-analysis was to assess the benefit of such preoperative treatment compared with no treatment before adrenalectomy for phaeochromocytoma.

METHODS

A systematic literature search was undertaken in MEDLINE, Web of Science and CENTRAL without language restrictions. Randomized and non-randomized comparative studies investigating preoperative α-blockade in phaeochromocytoma surgery were included. Data on perioperative safety, effectiveness and outcomes were extracted. Pooled results were calculated as an odds ratio or mean difference with 95 per cent confidence interval.

RESULTS

A total of four retrospective comparative studies were included investigating 603 patients undergoing phaeochromocytoma surgery. Mortality, cardiovascular complications, mean maximal intraoperative systolic and diastolic BP, and mean maximal intraoperative heart rate did not differ between patients with or without α-blockade. The certainty of the evidence was very low owing to the inferior quality of studies.

CONCLUSION

This meta-analysis has shown a lack of evidence for preoperative α-blockade in surgery for phaeochromocytoma. RCTs are needed to evaluate whether preoperative α-blockade can be abandoned.

Factors Affecting Cardiovascular Physiology in Cardiothoracic Surgery: Implications for Lumped-Parameter Modeling

Cardiothoracic surgeries are complex procedures during which the patient cardiovascular physiology is constantly changing due to various factors. Physiological changes begin with the induction of anesthesia, whose effects remain active into the postoperative period. Depending on the surgery, patients may require the use of cardiopulmonary bypass and cardioplegia, both of which affect postoperative physiology such as cardiac index and vascular resistance. Complications may arise due to adverse reactions to the surgery, causing hemodynamic instability. In response, fluid resuscitation and/or vasoactive agents with varying effects may be used in the intraoperative or postoperative periods to improve patient hemodynamics. These factors have important implications for lumped-parameter computational models which aim to assist surgical planning and medical device evaluation. Patient-specific models are typically tuned based on patient clinical data which may be asynchronously acquired through invasive techniques such as catheterization, during which the patient may be under the effects of drugs such as anesthesia. Due to the limited clinical data available and the inability to foresee short-term physiological regulation, models often retain preoperative parameters for postoperative predictions; however, without accounting for the physiologic changes that may occur during surgical procedures, the accuracy of these predictive models remains limited. Understanding and incorporating the effects of these factors in cardiovascular models will improve the model fidelity and predictive capabilities.

The Pathogenesis of Nonocclusive Mesenteric Ischemia: Implications for Research and Clinical Practice

Nonocclusive mesenteric ischemia (NOMI) is a condition that can encompass ischemia, inflammation, and infarction of the intestinal wall. In contrast to most patients with acute mesenteric ischemia, NOMI is distinguished by patent arteries and veins. The clinical presentation of NOMI is often insidious and nonspecific, resulting in a delayed diagnosis. Patients most at risk are those with severe acute and critical disease, including major surgery and trauma. Nonocclusive mesenteric ischemia is part of a spectrum, from mild, asymptomatic, and an unexpected finding on CT scanning, through to those exhibiting abdominal distension and peritonitis. Severe NOMI is associated with a significant mortality rate. This review of NOMI pathophysiology was conducted to document current concepts and evidence, to examine the implications for diagnosis and treatment, and to identify gaps in knowledge that might direct future research. The key pathologic mechanisms involved in the genesis of NOMI represent an exaggerated normal physiological response to maintain perfusion of vital organs at the expense of mesenteric perfusion. A supply-demand mismatch develops in the intestine due to the development of persistent mesenteric vasoconstriction resulting in reduced blood flow and oxygen delivery to the intestine, particularly to the vulnerable superficial mucosa. This mismatch can be exacerbated by raised intra-abdominal pressure, enteral nutrition, and the use of certain vasoactive drugs, ultimately resulting in the development of intestinal ischemia. Strategies for prevention, early detection, and treatment are urgently needed.

Extended Case Duration and Hypotension Are Associated With Higher-grade Postoperative Complications After Urinary Diversion for Non-oncological Disease

OBJECTIVE

To report survival for patients who undergo urinary diversion for benign indications and to identify risk factors for morbidity at 90 days.

METHODS

This is a retrospective review of consecutive urinary diversions with or without cystectomy for non-oncological indications at a single institution. The indication for diversion was intractable incontinence, upper tract deterioration, urinary fistula, and unmanageable bladder pain. Patients were categorized according to their most severe complication within 90 days of surgery, using the Clavien-Dindo system. Multivariable analysis was performed to identify factors associated with high-grade complications. Survival analysis was performed.

RESULTS

Between 2007 and 2014, 141 patients underwent urinary diversion for non-oncological indications. The postoperative rate of high-grade adverse events (class III or greater) was 28%. Risk factors for class III or greater complications at 90 days included prolonged intraoperative mean arterial pressure below 75% of baseline, operative duration greater than 343 minutes, and postoperative vasopressor requirement. Kaplan-Meier survival analysis demonstrated a 1- and 5-year survival of 88.4% and 77.2%, respectively. The long-term survival of patients who experienced higher-grade complications was not statistically different from the survival of the rest of the group. The study was limited by a retrospective design and sample size in identifying additional variables associated with increased risk of long-term mortality.

CONCLUSION

Urinary diversion for non-oncological conditions has a good 5-year survival in this cohort. Extended case duration and hemodynamic instability during or immediately after urinary diversion are associated with a high-grade complication within 90 days of the procedure.