Vasoplegia After Cardiovascular Procedures—Pathophysiology and Targeted Therapy

Vasoplegia in patients following ventricular assist device explant and heart transplantation

BACKGROUND

Vasoplegia has been shown to be associated with increased morbidity and mortality in patients undergoing cardiac surgery. It has been previously stated that low pulsatile states as seen with current left ventricular assist devices (LVADs) may contribute to vasoplegia post LVAD-explant and heart transplant. We sought to examine the literature regarding vasoplegia in the post-operative setting for patients undergoing LVAD explant and heart transplant.

METHOD

A literature review was conducted to firstly define vasoplegia in the setting of LVAD patients, and secondly to better understand the relationship between vasoplegia and LVAD explantation in the postoperative heart transplant patient cohort. A keyword search of 'vasoplegia' OR 'vasoplegic' AND 'transplant' was used. Search engines used were PubMed, Cochrane Library, ClinicalTrials.gov, Ovid, Scopus and grey literature.

RESULTS

17 studies met the selection criteria for review. Three key themes emerged from the literature. Firstly, there is limited consensus regarding the definition of vasoplegia. Secondly, patients with LVADs experienced higher rates of vasoplegia following heart transplant than their counterparts and thirdly, increased cardiopulmonary bypass time was associated with a higher rate of vasoplegia.

CONCLUSION

Vasoplegia is not clearly defined in the literature as it pertains to the LVAD patient cohort. Patients bridged with LVADs appear to have higher rates of vasoplegia, however the aetiology of this is unclear and may be associated with continuous flow physiology or prolonged cardiopulmonary bypass time. A universal definition will aid in risk stratification, early recognition and management.

Methylene Blue for Vasoplegia During Extracorporeal Membrane Oxygenation Support

OBJECTIVE

The treatment of refractory vasodilatory shock in patients undergoing extracorporeal membrane oxygenation (ECMO) is an area in which there is minimal literature. Based on previous literature, the authors hypothesized that at least 40% of ECMO patients with vasoplegia would respond positively to methylene blue (MB) administration and that those who responded to MB would have increased survival.

DESIGN

Retrospective observational study.

SETTING

Single institution, quaternary care hospital.

PARTICIPANTS

The study comprised 45 patients who received MB for vasoplegia during ECMO.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 45 patients who received MB, 25 patients (55.6%) experienced a ≥10% increase in mean arterial pressure (MAP) and a reduction in norepinephrine dosing in the one-to-two hour interval after MB administration. There was a trend for improvement in survival to discharge for those who responded to MB (32% v 10%; p = 0.15). In addition, patients who did not have at least a >5% increase in MAP (29 experienced a >5% increase and 16 experienced a ≤5% increase) after MB administration, experienced 100% mortality (p = 0.008).

CONCLUSION

This study suggested that approximately 50% of ECMO patients with vasoplegia can be expected to respond to MB with a >10% MAP improvement. The lack of a blood pressure response >5% after MB administration may portend poor survival. Larger prospective studies are needed to verify these preliminary results.

Use of the Hypotension Prediction Index During Cardiac Surgery

OBJECTIVE

The hypotension prediction index (HPI) is a novel parameter developed by Edwards Lifesciences (Irvine, CA) that is obtained through an algorithm based on arterial pressure waveform characteristics. Past studies have demonstrated its accuracy in predicting hypotensive events in noncardiac surgeries. The authors aimed to evaluate the use of the HPI in cardiac surgeries requiring cardiopulmonary bypass (CPB).

DESIGN

Prospective cohort feasibility study.

SETTING

Single university medical center.

PARTICIPANTS

Sequential adult patients undergoing elective cardiac surgeries requiring CPB between October 1, 2018, and December 31, 2018.

INTERVENTIONS

HPI monitor was connected to the patient's arterial pressure transducer. Anesthesiologists and surgeons were blinded to the monitor output.

MEASUREMENTS AND MAIN RESULTS

HPI values and hypotensive events were recorded before and after CPB. The primary outcomes were the area under the curve (AUC) of the receiver operating characteristic curve, sensitivity, and specificity of HPI predicting hypotension. The AUC, sensitivity, and specificity for HPI lead time to hypotension five minutes before the event were 0.90 (95% confidence interval [CI]: 0.853-0.949), 84% (95% CI: 77.7-90.5), and 84% (95% CI: 70.9-96.8), respectively. Ten minutes before the event AUC, sensitivity, and specificity for HPI lead time to hypotension were 0.83 (95% CI: 0.750-0.905), 79% (95% CI: 69.8-88.1), and 74% (95% CI: 58.8-89.6), respectively. Fifteen minutes before the hypotensive event AUC, sensitivity, and specificity for HPI lead time to hypotension were 0.83 (95% CI: 0.746-0.911), 79% (95% CI: 68.4-89.0), and 74% (95% CI: 58.8-89.6), respectively.

CONCLUSION

HPI predicted hypotensive episodes during cardiac surgeries with a high degree of sensitivity and specificity.

Biomaker evaluation for major adverse cardiovascular event development in patients undergoing cardiac Surgery

Objectives

The postoperative period of cardiac surgery (CS) is associated with the development of major adverse cardiovascular events (MACEs). However, the evaluation of MACE after CS by means of biomarkers is poorly developed. We aimed to evaluate postoperative biomarkers that could be associated with MACE.

Methods

Two Hundred and ten patients who underwent CS were enrolled during the study period. The diagnosis of MACE was defined as the presence of at least one of the following complications: acute myocardial infarction, heart failure, stroke presented during intensive care unit (ICU) stay, and 30-day mortality after CS. High-sensitive troponin T (hs-TnT), C-reactive protein, procalcitonin, interleukin-6, and immature platelet fraction (IPF) were measured on ICU admission and after 24 h. The difference between both measurements (Δ) was calculated to assess their association with MACE. Early infected patients (n=13) after CS were excluded from final analysis.

Results

The most frequent surgery was single-valve surgery (n=83; 38%), followed by coronary artery bypass graft (n=72; 34%). Postoperative MACE was diagnosed in 31 (14.8%) patients. Biomarker dynamics showed elevated values at 24 h compared with those at ICU admission in patients with MACE versus no-MACE. Multivariate analysis showed that ΔIPF (OR: 1.47; 95% CI: 1.110-1.960; p=0.008) and Δhs-TnT (OR: 1.001; 95% CI: 1.0002-1.001; p=0.008) were independently associated with MACE.

Conclusions

These findings suggest that postoperative ΔIPF and Δhs-TnT may be useful biomarkers for the identification of patients at risk of MACE development.

Acute Unloading Effects of Sildenafil Enhance Right Ventricular-Pulmonary Artery Coupling in Heart Failure

BACKGROUND

Phosphodiesterase-5A inhibitors (PDE5i) are sometimes used in patients with advanced heart failure with reduced ejection fraction before heart transplant or left ventricular assist device implantation to decrease right ventricular (RV) afterload and mitigate the risk of right heart failure. Conflicting evidence exists regarding the impact of these drugs on RV contractility. The aim of this study was to explore the acute effects of PDE5i on ventricular-vascular coupling and load-independent RV contractility.

METHODS

Twenty-two patients underwent right heart catheterization and gated equilibrium blood pool single photon emission computed tomography, before and after 20 mg intravenous sildenafil. Single photon emission computed tomography and right heart catheterization-derived data were used to calculate RV loading and contractility.

RESULTS

PDE5i induced a decrease in the right atrial pressure (-43%), pulmonary artery (PA) mean pressure (-26%), and PA wedge pressure (PAWP; -23%), with favorable reductions in pulmonary vascular resistance (-41%) and PA elastance (-40%), and increased cardiac output (+13%) (all P < 0.01). The RV ejection fraction increased with sildenafil (+20%), with no change of RV contractility (P = 0.74), indicating that the improvement in the RV ejection fraction was related to enhanced RV-PA coupling (r = 0.59, P = 0.004) by a decrease in the ventricular load. RV diastolic compliance increased with sildenafil. The decrease in the PAWP correlated with RV end-diastolic volume decrease; no relationship was observed with the change in LV transmural pressure, suggesting decreased pericardial constraint.

CONCLUSIONS

Acute PDE5i administration has profound RV afterload-reducing effects, improves the RVEF, decreases RV volumes, and decreases the PAWP, predominantly through relief of pericardial constraint, without effects on RV chamber contractility. These findings support further study of PDE5i in protection of RV function in advanced heart failure with reduced ejection fraction who are at risk of RV failure.

Vasopressor Therapy in Cardiac Surgery-An Experts' Consensus Statement

Hemodynamic conditions with reduced systemic vascular resistance commonly are observed in patients undergoing cardiac surgery and may range from moderate reductions in vascular tone, as a side effect of general anesthetics, to a profound vasodilatory syndrome, often referred to as vasoplegic shock. Therapy with vasopressors is an important pillar in the treatment of these conditions. There is limited guidance on the appropriate choice of vasopressors to restore and optimize systemic vascular tone in patients undergoing cardiac surgery. A panel of experts in the field convened to develop statements and evidence-based recommendations on clinically relevant questions on the use of vasopressors in cardiac surgical patients, using a critical appraisal of the literature following the GRADE system and a modified Delphi process. The authors unanimously and strongly recommend the use of norepinephrine and/or vasopressin for restoration and maintenance of systemic perfusion pressure in cardiac surgical patients; despite that, the authors cannot recommend either of these drugs with respect to the risk of ischemic complications. The authors unanimously and strongly recommend against using dopamine for treating post-cardiac surgery vasoplegic shock and against using methylene blue for purposes other than a rescue therapy. The authors unanimously and weakly recommend that clinicians consider early addition of a second vasopressor (norepinephrine or vasopressin) if adequate vascular tone cannot be restored by a monotherapy with either norepinephrine or vasopressin and to consider using vasopressin as a first-line vasopressor or to add vasopressin to norepinephrine in cardiac surgical patients with pulmonary hypertension or right-sided heart dysfunction.

Risk Factors Associated with In-Hospital Mortality for Patients with Acute Abdomen After Cardiac Surgery

OBJECTIVES

Management of acute abdomen (AA) differs due to the heterogeneity of underlying pathophysiology. Complications of AA and its overall outcome after cardiac surgery are known to be associated with poor results. The aim of this retrospective analysis was to evaluate risk factors for AA in patients undergoing cardiac surgery.

METHODS

Between December 2011 and December 2014, a total of 131 patients with AA after cardiac surgery were identified and retrospectively analyzed using our institutional database. Statistical analysis of risk factors concerning in-hospital mortality of mentioned patient cohort was performed using IBM SPSS Statistics.

RESULTS

Overall in-hospital mortality was 54.2% (71/131). Analyzing in-hospital non-survivors (NS) versus in-hospital survivors (S) peripheral artery disease (28.2% vs. 11.7%; p = 0.03), the need for assist device therapy (33.8% vs. 16.7%; p = 0.03) and the requirement of hemodialysis (67.6% vs. 23.3%; p < 0.01) were significantly higher in NS. Furthermore, lactic acid values at onset of symptoms were shown to be significantly higher in NS (5.7 ± 5.7 mmol/L vs. 2.8 ± 2.9 mmol/L; p < 0.01). Assured diagnosis of mesenterial ischemia was strongly associated with worse outcome (odds ratio 10.800, 95% confidence interval 2.003-58.224; p = 0.006).

CONCLUSION

In conclusion, in critically ill patients after performed cardiac surgery peripheral vascular disease, need for supportive hemodynamic assist device systems and occurrence of renal failure are risk factors associated with worsen outcome. Additionally, rise of lactic acid could potentially be associated with onset of intestinal malperfusion and should be taken into account in therapeutic decisions preventing fatal mesenterial ischemia.

Continuous Heart Volume Monitoring by Fully Implantable Soft Strain Sensor

Cardiothoracic open-heart surgery has revolutionized the treatment of cardiovascular disease, the leading cause of death worldwide. After the surgery, hemodynamic and volume management can be complicated, for example in case of vasoplegia after endocarditis. Timely treatment is crucial for outcomes. Currently, treatment decisions are made based on heart volume, which needs to be measured manually by the clinician each time using ultrasound. Alternatively, implantable sensors offer a real-time window into the dynamic function of our body. Here it is shown that a soft flexible sensor, made with biocompatible materials, implanted on the surface of the heart, can provide continuous information of the heart volume after surgery. The sensor works robustly for a period of two days on a tensile machine. The accuracy of measuring heart volume is improved compared to the clinical gold standard in vivo, with an error of 7.1 mL for the strain sensor versus impedance and 14.0 mL versus ultrasound. Implanting such a sensor would provide essential, continuous information on heart volume in the critical time following the surgery, allowing early identification of complications, facilitating treatment, and hence potentially improving patient outcome.

Postoperative Serotonin Syndrome Following Methylene Blue Administration for Vasoplegia After Cardiac Surgery: A Case Report and Review of the Literature

Serotonin syndrome is a potentially life-threatening condition associated with increased serotonergic activity in the central nervous system. The increasing incidence of this condition is thought to parallel the increasing use of serotonergic agents in medical practice. The selective serotonin reuptake inhibitors are perhaps the most commonly implicated group of medications associated with serotonin syndrome. This case report describes the occurrence of postoperative serotonin syndrome in a patient on long-term sertraline who underwent coronary artery bypass graft and was treated with methylene blue for perioperative vasoplegia. It delineates the various clinical features commonly encountered and illustrates the recommended management modalities, including prevention, for this potentially lethal medical emergency. With prompt diagnosis and expeditious treatment, the patient has had full recovery.

The use of hydroxocobalamin for vasoplegic syndrome in left ventricular assist device patients

We demonstrate evidence supporting the efficacy of hydroxocobalamin in reducing vasopressor requirements for LVAD patients with refractory vasoplegia. Further study is needed to substantiate these findings and determine its optimal use in practice.

Treatment With Angiotensin II Is Associated With Rapid Blood Pressure Response and Vasopressor Sparing in Patients With Vasoplegia After Cardiac Surgery: A Post-Hoc Analysis of Angiotensin II for the Treatment of High-Output Shock (ATHOS-3) Study

OBJECTIVE

The present study investigated outcomes in patients with vasoplegia after cardiac surgery treated with angiotensin II plus standard-of-care vasopressors. Vasoplegia is a common complication in cardiac surgery with cardiopulmonary bypass and is associated with significant morbidity and mortality. Approximately 250,000 cardiac surgeries with cardiopulmonary bypass are performed in the United States annually, with vasoplegia occurring in 20%to-27% of patients.

DESIGN

Post-hoc analysis of the Angiotensin II for the Treatment of High-Output Shock (ATHOS-3) study.

SETTING

Multicenter, multinational study.

PARTICIPANTS

Sixteen patients with vasoplegia after cardiac surgery with cardiopulmonary bypass were enrolled.

INTERVENTIONS

Angiotensin II plus standard-of-care vasopressors (n = 9) compared with placebo plus standard-of-care vasopressors (n = 7).

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was mean arterial pressure response (mean arterial pressure ≥75 mmHg or an increase from baseline of ≥10 mmHg at hour 3 without an increase in the dose of standard-of-care vasopressors). Vasopressor sparing and safety also were assessed. Mean arterial pressure response was achieved in 8 (88.9%) patients in the angiotensin II group compared with 0 (0%) patients in the placebo group (p = 0.0021). At hour 12, the median standard-of-care vasopressor dose had decreased from baseline by 76.5% in the angiotensin II group compared with an increase of 7.8% in the placebo group (p = 0.0013). No venous or arterial thrombotic events were reported.

CONCLUSION

Patients with vasoplegia after cardiac surgery with cardiopulmonary bypass rapidly responded to angiotensin II, permitting significant vasopressor sparing.

Angiotensin II for Critically Ill Patients With Shock After Heart Transplant

Patients undergoing heart transplant are at high risk for vasodilatory shock in the postoperative period, due to a combination of vascular dysfunction from end-stage heart failure and inflammatory response to cardiopulmonary bypass and, increasingly, long-term exposure to nonpulsatile blood flow in those who have received a left ventricular assist device as a bridge to transplant. Patients who have this vasoplegic syndrome, which may be refractory to traditional agents used in the treatment of shock, are vulnerable to organ dysfunction and death. Angiotensin II (ANG-2) is of increasing interest as an adjunct to traditional therapy, both for improvement in blood pressure and for sparing the use of high-dose catecholamine vasopressors. This case series describes the use of ANG-2 in 4 clinical scenarios for the treatment of shock due to heart transplant surgery, supporting its use in this role and justifying further prospective studies to clarify the appropriate place for ANG-2 in the hierarchy of adjunctive therapies.

Albumin Use After Cardiac Surgery

Objectives

To investigate the effect of albumin exposure in ICU after cardiac surgery on hospital mortality, complications, and costs.

Design

A retrospective, single-center cohort study with economic evaluation.

Setting

Cardiothoracic ICU in Australia.

Patients

Adult patients admitted to the ICU after cardiac surgery.

Interventions

None.

Measurements and Main Results

Comparison of outcomes and costs in ICU after cardiac surgery based on 4% human albumin exposure. During the study period, 3,656 patients underwent cardiac surgery. After exclusions, 2,594 patients were suitable for analysis. One-thousand two-hundred sixty-four (48.7%) were exposed to albumin and 19 (1.4%) of those died. The adjusted hospital mortality of albumin exposure compared with no albumin was not significant (odds ratio, 1.24; 95% CI, 0.56-2.79; p = 0.6). More patients exposed to albumin returned to the operating theater for bleeding and/or tamponade (6.1% vs 2.1%; odds ratio, 2.84; 95% CI, 1.81-4.45; p < 0.01) and received packed red cell transfusions (p < 0.001). ICU and hospital lengths of stay were prolonged in those exposed to albumin (mean difference, 18 hr; 95% CI, 10.3-25.6; p < 0.001 and 87.5 hr; 95% CI, 40.5-134.6; p < 0.001). Costs (U.S. dollar) were higher in patients exposed to albumin, compared with those with no albumin exposure (mean difference in ICU costs, $2,728; 95% CI, $1,566-3,890 and mean difference in hospital costs, $5,427; 95% CI, $3,294-7,560).

Conclusions

There is no increased mortality in patients who are exposed to albumin after cardiac surgery. The patients exposed to albumin had higher illness severity, suffered more complications, and incurred higher healthcare costs. A randomized controlled trial is required to determine whether albumin use is effective and safe in this setting.

Efficacy of Nitric Oxide Administration During Neonatal Cardiopulmonary Bypass

This editorial accompanies an original research article by Dr Elzein and colleagues describing findings of a randomized, placebo-controlled trial of nitric oxide administration during cardiopulmonary bypass surgery in infants undergoing the Norwood procedure.

Vasoplegia after cardiopulmonary bypass: A narrative review of pathophysiology and emerging targeted therapies

Cardiovascular disease remains the leading cause of death in the United States, and cardiopulmonary bypass is a cornerstone in the surgical management of many related disease states. Pathophysiologic changes associated both with extracorporeal circulation and shock can beget a syndrome of low systemic vascular resistance paired with relatively preserved cardiac output, termed vasoplegia. While increased vasopressor requirements accompany vasoplegia, related pathophysiologic mechanisms may also lead to true catecholamine resistance, which is associated with further heightened mortality. The introduction of a second non-catecholamine vasopressor, angiotensin II, and non-specific nitric oxide scavengers offers potential means by which to manage this challenging phenomenon. This narrative review addresses both the definition, risk factors, and pathophysiology of vasoplegia and potential therapeutic interventions.

Diabetes Insipidus After Discontinuation of Vasopressin Infusion for Treatment of Shock

OBJECTIVES

Vasopressin has achieved common usage for the treatment of catecholamine-requiring and catecholamine-resistant shock. Diabetes insipidus is a syndrome characterized by excretion of abnormally large volumes of dilute urine. To date, very few reports of diabetes insipidus after discontinuation of vasopressin infusion have been published; the majority of previous reports describe neurosurgical patients. The purpose of the present study was to investigate the occurrence rate of diabetes insipidus after discontinuation of vasopressin infusion among patients treated with vasopressin infusion for shock.

DESIGN

Retrospective analysis of electronic health records of patients receiving continuous vasopressin infusion for the treatment of shock within a 5-year period (2012-2016).

SETTING

Medical, surgical, and cardiothoracic ICUs within one academic medical center.

PATIENTS

One-thousand eight-hundred ninety-six patients received vasopressin infusion for the treatment of shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The occurrence rate of diabetes insipidus after discontinuation of vasopressin infusion was 1.53% among all patients. Sixteen of 29 patients with diabetes insipidus after discontinuation of vasopressin infusion had undergone cardiothoracic intervention, such as coronary artery bypass graft and valve replacement surgery, extracorporeal membrane oxygenation, and placement of ventricular assist devices. No neurosurgical patients were identified in our cohort. In a control group of patients receiving norepinephrine but not vasopressin infusion for treatment of shock, criteria for diabetes insipidus were observed in two of 1,320 subjects (0.15%).

CONCLUSIONS

Despite a paucity of published reports, diabetes insipidus after discontinuation of vasopressin infusion appears not to be a rare phenomenon, and is likely to be encountered by intensivists who regularly employ vasopressin for the treatment of vasoplegic shock. Previous reports consisted predominantly of neurosurgical patients. Our findings demonstrate the occurrence of diabetes insipidus after discontinuation of vasopressin infusion among patients with septic shock as well as vasoplegic shock after cardiothoracic intervention. The mechanism of diabetes insipidus after discontinuation of vasopressin infusion remains to be elucidated but may involve transient downregulation of V2 receptors induced by exposure to supraphysiological doses of vasopressin.

Association between high dose catecholamine support and liver dysfunction following cardiac surgery

BACKGROUND

Cardiac surgery using cardiopulmonary bypass is a well-established procedure. However, up to 20% to 30% of patients require high dose vasopressor or inotropic support following surgery, enhancing the risk of organ dysfunction and impacting mortality. Nonalcoholic fatty liver disease (NAFLD) is a frequent finding in these patients and may be involved in the pathophysiology of vasoplegia and cardiac failure.

METHODS

Retrospective analysis of 463 patients undergoing elective cardiac surgery in 2014 at our institution. NAFLD was defined using the NAFLD fibrosis score and the vasoactive-inotropy score was used to determine postoperative vasopressor and inotropic dependency.

RESULTS

Patients with NAFLD more often presented with high vasopressor or inotropic support compared to patients without NAFLD, resulting in significant differences after 6 hours (n = 20 [27.0%] of 74 patients), 12 hours (n = 20 [27.0%] of 74 patients), and on the first postoperative day (n = 12 [16.4%] of 73 patients) of intensive care unit (ICU) treatment. Multivariate analysis revealed time of catecholamine application (P = .001), preoperative left ventricular ejection fraction (P = .001), type of surgery (P = .001), model of endstage liver disease on hospital admission (P = .002), pre-existing pulmonary hypertension (P = .004) and NAFLD-time interaction (P = .05) as independent predictors of high vasopressor and inotropic support. Patients with NAFLD had higher degrees of extrahepatic organ dysfunction, were more dependent on hemodialysis, spent more days in the ICU and within the hospital. Patients with NAFLD and high catecholamine support had the highest mortality rates among the study population.

CONCLUSIONS

NAFLD is a common finding in elective cardiac surgery patients. Anesthesiologists and intensivists should be sensitive for the specific risk profile of this population.

Continuation of Newly Initiated Midodrine Therapy After Intensive Care and Hospital Discharge: A Single-Center Retrospective Study

OBJECTIVES

Midodrine is an α1-agonist approved for orthostatic hypotension. Recently, it has received attention as an oral vasopressor to facilitate ICU discharge. The purpose of this study was to identify the incidence of continuation of newly initiated midodrine upon ICU and hospital discharge and identify risk factors associated with its occurrence.

DESIGN

Single-center retrospective study.

SETTING

ICU patients from January 2011 to October 2016 at Mayo Clinic, Rochester.

PATIENTS

Adult patients admitted to any ICU who received new midodrine for hypotension and survived to discharge.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

During the study period, 1,010 patients were newly started on midodrine and survived to ICU discharge. Midodrine was continued in 67% (672/1,010) of patients at ICU discharge. Admission to cardiovascular surgery ICU and mixed medical/surgical ICU was a risk factor for midodrine continuation at ICU discharge (odds ratio, 3.94 [2.50-6.21] and 2.03 [1.29-3.20], respectively). At hospital discharge, 34% (311/909) of patients were continued on midodrine therapy. History of congestive heart failure predicted midodrine continuation at hospital discharge (odds ratio, 1.49 [1.05-2.12]). Hypertension and use of mechanical ventilation were associated with a decreased odds of midodrine prescription at both ICU and hospital discharge. Of those discharged from the ICU or hospital on midodrine, 50% were concomitantly prescribed antihypertensives. Discharge from the ICU on midodrine was associated with a significantly shorter ICU length of stay (7.5 ± 8.9 vs 10.6 ± 13.4 d) and reduced risk of in-hospital mortality (hazard ratio, 0.47 [95% CI, 0.32-0.70]; p < 0.001), despite no difference in baseline severity of illness scores. In contrast, patients discharged from the hospital on midodrine had a higher risk of 1-year mortality (hazard ratio, 1.60 [95% CI, 1.26-2.04]; p < 0.001).

CONCLUSIONS

This study established a high prevalence of midodrine continuation in transitions of care. The risks and benefits of this practice remain unclear. Future studies should explore the impact of this practice on patient outcomes and resource utilization. These insights could be used to model interventions for proper tapering, discontinuation, or follow-up of new start midodrine.

Vasoplegic syndrome following cardiothoracic surgery-review of pathophysiology and update of treatment options

Vasoplegic syndrome is a common occurrence following cardiothoracic surgery and is characterized as a high-output shock state with poor systemic vascular resistance. The pathophysiology is complex and includes dysregulation of vasodilatory and vasoconstrictive properties of smooth vascular muscle cells. Specific bypass machine and patient factors play key roles in occurrence. Research into treatment of this syndrome is limited and extrapolated primarily from that pertaining to septic shock, but is evolving with the expanded use of catecholamine-sparing agents. Recent reports demonstrate potential benefit in novel treatment options, but large clinical trials are needed to confirm.

Vasoplegia During Cardiopulmonary Bypass: Current Literature and Rescue Therapy Options

Vasoplegia syndrome in the cardiac surgical intensive care unit and postoperative period has been an area of interest to clinicians because of its prevalence and effects on morbidity and mortality. However, there is a paucity of evidence regarding the treatment of vasoplegia syndrome during cardiopulmonary bypass (on-CPB VS). This review aims to detail the incidence, outcomes, and possible treatment options for patients who develop vasoplegia during bypass. The pharmacologic rescue agents discussed are used in cases in which vasoplegia during CPB is refractory to standard catecholamine agents, such as norepinephrine, epinephrine, and phenylephrine. Methods to improve vasoplegia during CPB can be both pharmacologic and nonpharmacologic. In particular, optimization of CPB parameters plays an important nonpharmacologic role in vasoplegia during CPB. Pharmacologic agents that have been demonstrated as being effective in vasoplegia include vasopressin, terlipressin, methylene blue, hydroxocobalamin, angiotensin II (Giapreza), vitamin C, flurbiprofen (Ropion), and hydrocortisone. Although these agents have not been specifically evaluated for vasoplegia during CPB, they have shown signs of effectiveness for vasoplegia postoperatively to varying degrees. Understanding the evidence for, dosing, and side effects of these agents is crucial for cardiac anesthesiologists when treating vasoplegia during CPB bypass.

The use of data science to analyse physiology of oxygen delivery in the extracorporeal circulation

Background

Recent scientific reports have brought into light a new concept of goal-directed perfusion (GDP) that aims to recreate physiological conditions in which the risk of end-organ malperfusion is minimalized. The aim of our study was to analyse patients’ interim physiology while on cardiopulmonary bypass based on the haemodynamic and tissue oxygen delivery measurements. We also aimed to create a universal formula that may help in further implementation of the GDP concept.

Methods

We retrospectively analysed patients operated on at the Wroclaw University Hospital between June 2017 and December 2018. Since our observations provided an extensive amount of data, including the patients’ demographics, surgery details and the perfusion-related data, the Data Science methodology was applied.

Results

A total of 272 (mean age 62.5 ± 12.4, 74% male) cardiac surgery patients were included in the study. To study the relationship between haemodynamic and tissue oxygen parameters, the data for three different values of DO₂i (280 ml/min/m², 330 ml/min/m² and 380 ml/min/m²), were evaluated. Each set of those lines showed a descending function of CI in Hb concentration for the set DO₂i.

Conclusions

Modern calculation tools make it possible to create a common data platform from a very large database. Using that methodology we created models of haemodynamic compounds describing tissue oxygen delivery. The obtained unique patterns may both allow the adaptation of the flow in relation to the patient’s unique morphology that changes in time and contribute to wider and safer implementation of perfusion strategy which has been tailored to every patient’s individual needs.

Evaluation of the delta of immature platelet fraction as a predictive biomarker of inflammatory response after cardiac surgery

AIMS

Cardiac surgery (CS) can induce an inflammatory response (IR) that is associated with poorer outcomes. Immature platelets are among the factors that may be associated with IR development. We aimed to evaluate whether immature platelet fraction (IPF) could be a predictive biomarker for IR and whether IPF could improve the prognosis assessment of IR for Acute Physiologic and Chronic Health Evaluation (APACHE II) and Sequential Organ Failure Assessment (SOFA) following CS.

METHODS

Three-hundred and twenty-seven (327) patients who underwent CS were enrolled during the study period. IR was defined according to the need for vasopressor support (>48 hours). Perioperative variables and outcomes were registered in our database. IPF was measured immediately following CS and at 24 hours by Sysmex XN analyzer and the difference between both measurements (ΔIPF) was calculated. To assess the relationship between ΔIPF and IR, univariate and multivariate logistic regression were performed. To analyse the additive value of ΔIPF in APACHE II and SOFA scores in predicting IR, an area under the receiver operating characteristic (AUROC) curve was calculated.

RESULTS

Among 327 patients included, 60 patients (18.3%) developed IR. Multivariate analysis showed ΔIPF was significantly associated with IR (OR: 1.26; 95% CI: 1.01 to 1.56; p=0.038). The combination of ΔIPF with scores improved the AUROC for IR prediction: 0.629 vs 0.728 (p=0.010) for APACHE II and 0.676 vs 0.715 (p=0.106) for SOFA.

CONCLUSION

These findings suggested that ΔIPF may be a useful and low-cost biomarker for the early identification of patients at risk of IR development.

Predictors and Clinical Outcomes of Vasoplegia in Patients Bridged to Heart Transplantation With Continuous-Flow Left Ventricular Assist Devices

Background

The presence of a durable left ventricular assist device (LVAD) is associated with increased risk of vasoplegia in the early postoperative period following heart transplantation (HT). However, preoperative predictors of vasoplegia and its impact on survival after HT are unknown. We sought to examine predictors and outcomes of patients who develop vasoplegia after HT following bridging therapy with an LVAD.

Methods and Results

We identified 94 patients who underwent HT after bridging with continuous‐flow LVAD from 2008 to 2018 at a single institution. Vasoplegia was defined as persistent low vascular resistance requiring ≥2 intravenous vasopressors within 48 hours after HT for >24 hours to maintain mean arterial pressure >70 mm Hg. Overall, 44 patients (46.8%) developed vasoplegia after HT. Patients with and without vasoplegia had similar preoperative LVAD, echocardiographic, and hemodynamic parameters. Patients with vasoplegia were significantly older; had longer LVAD support, higher preoperative creatinine, longer cardiopulmonary bypass time, and higher Charlson comorbidity index; and more often underwent combined organ transplantation. In a multivariate logistic regression model, older age (odds ratio: 1.08 per year; P=0.010), longer LVAD support (odds ratio: 1.06 per month; P=0.007), higher creatinine (odds ratio: 3.9 per 1 mg/dL; P=0.039), and longer cardiopulmonary bypass time (odds ratio: 1.83 per hour; P=0.044) were independent predictors of vasoplegia. After mean follow‐up of 4.0 years after HT, vasoplegia was associated with increased risk of all‐cause mortality (hazard ratio: 5.20; 95% CI, 1.71–19.28; P=0.003).

Conclusions

Older age, longer LVAD support, impaired renal function, and prolonged intraoperative CPB time are independent predictors of vasoplegia in patients undergoing HT after LVAD bridging. Vasoplegia is associated with worse prognosis; therefore, detailed assessment of these predictors can be clinically important.

Medical Optimization and Liberation of Adult Patients From VA-ECMO

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can be an efficacious cardiopulmonary support for adults as rescue from refractory cardiogenic shock. It is best employed as a bridging strategy to recovery or alternative support rather than sustained, long-term mechanical circulatory support. The purpose of this paper is to discuss strategies to optimize patient management on VA-ECMO and approaches to promote successful separation from support. Rapid medical optimization will assist in reducing the time on VA-ECMO, thereby improving the likelihood of patient salvage. Suitably trained physicians and personnel, guided by structured protocols, can promote excellence in team care and provision of consistent management. Focusing on anticoagulation, careful neurologic monitoring, prevention of leg ischemia, awareness of differential hypoxemia, optimizing mechanical ventilation, identifying and timely intervention for left-ventricular distension (LVD), along with a strategic weaning algorithm, can prevent significant morbidity and mortality. LVD physiology, diagnosis, and risk factors are reviewed. Indications for LV decompression, along with medical and mechanical management options, are elucidated.

Adrenergic Downregulation in Critical Care: Molecular Mechanisms and Therapeutic Evidence

Catecholamines remain the mainstay of therapy for acute cardiovascular dysfunction. However, adrenergic receptors quickly undergo desensitization and downregulation after prolonged stimulation. Moreover, prolonged exposure to high circulating catecholamines levels is associated with several adverse effects on different organ systems. Unfortunately, in critically ill patients, adrenergic downregulation translates into progressive reduction of cardiovascular response to exogenous catecholamine administration, leading to refractory shock. Accordingly, there has been a growing interest in recent years toward use of noncatecholaminergic inotropes and vasopressors. Several studies investigating a wide variety of catecholamine-sparing strategies (eg, levosimendan, vasopressin, β-blockers, steroids, and use of mechanical circulatory support) have been published recently. Use of these agents was associated with improvement in hemodynamics and decreased catecholamine use but without a clear beneficial effect on major clinical outcomes. Accordingly, additional research is needed to define the optimal management of catecholamine-resistant shock.

Toward the Existence of a Sympathetic Neuroplasticity Adaptive Mechanism Influencing the Immune Response. A Hypothetical View-Part II

In the preceding work, a hypothesis on the existence of a specific neural plasticity program from sympathetic fibers innervating secondary lymphoid organs was introduced. This proposed adaptive mechanism would involve segmental retraction and degeneration of noradrenergic terminals during the immune system (IS) activation followed by regeneration once the IS returns to the steady-state. Starting from such view, this second part presents clinical and experimental evidence allowing to envision that this sympathetic neural plasticity mechanism is also operative on inflamed non-lymphoid peripheral tissues. Importantly, the sympathetic nervous system regulates most of the physiological bodily functions, ranging from cardiovascular, respiratory and gastro-intestinal functions to endocrine and metabolic ones, among others. Thus, it seems sensible to think that compensatory programs should be put into place during inflammation in non-lymphoid tissues as well, to avoid the possible detrimental consequences of a sympathetic blockade. Nevertheless, in many pathological scenarios like severe sepsis, chronic inflammatory diseases, or maladaptive immune responses, such compensatory programs against noradrenergic transmission impairment would fail to develop. This would lead to a manifest sympathetic dysfunction in the above-mentioned settings, partly accounting for their underlying pathophysiological basis; which is also discussed. The physiological/teleological significance for the whole neural plasticity process is postulated, as well.

When the pressure drops: A case of vasoplegia during a structural heart intervention

A 67-year-old male underwent general anesthesia for left atrial appendage occlusion. During the procedure, the patient developed catecholamine refractory hypotension requiring the administration of several vasopressin boluses to maintain adequate perfusion pressure. At the conclusion of the procedure, mild venous bleeding necessitated the administration of protamine. This led to a further decrease in the patient's blood pressure. Tamponade and continued volume loss were quickly ruled out leading to a diagnosis of vasoplegia syndrome (VS). The patient was appropriately treated with a vasopressin infusion with normalization of blood pressure and no significant morbidity or adverse outcome. With the use of general anesthesia during structural heart interventions on the rapid rise, we discuss the two common causes for vasoplegia along with evidence-based treatments and possible prevention strategies.

High-Dose Vitamin B12 in Vasodilatory Shock: A Narrative Review

Vasodilatory shock, as observed in postoperative states and sepsis, is hallmarked by low systemic vascular resistance and low blood pressure compensated by increased cardiac output. Gasotransmitters, such as nitric oxide and hydrogen sulfide, are implicated in the development and perpetuation of vasodilatory shock. Established therapies do not target these physiologic drivers of vasodilation. Due to their nontoxic and pleotropic effects, micronutrients are being used as rescue therapy in postoperative vasoplegia and septic shock. Here, we outline the pathophysiology of vasodilatory shock, describe the rationale for vitamin B12 (hydroxocobalamin) in vasodilatory shock, and identify literature evaluating its use in vasoplegic states.

Preimplant Phosphodiesterase-5 Inhibitor Use Is Associated With Higher Rates of Severe Early Right Heart Failure After Left Ventricular Assist Device Implantation

Background Early right heart failure (RHF) occurs commonly in left ventricular assist device (LVAD) recipients, and increased right ventricular (RV) afterload may contribute. Selective pulmonary vasodilators, like phosphodiesterase-5 inhibitors (PDE5i), are used off-label to reduce RV afterload before LVAD implantation, but the association between preoperative PDE5i use and early RHF after LVAD is unknown. Methods and Results We analyzed adult patients from the INTERMACS registry (Interagency Registry for Mechanically Assisted Circulatory Support) who received a continuous flow LVAD after 2012. Patients on PDE5i were propensity-matched 1:1 to controls. The primary outcome was the incidence of severe early RHF, defined as the composite of death from RHF within 30 days, need for RV assist device support within 30 days, or use of inotropes beyond 14 days. Of 11 544 continuous flow LVAD recipients, 1199 (10.4%) received preoperative PDE5i. Compared to controls, patients on PDE5i had higher pulmonary artery systolic pressure (53.4 mm Hg versus 49.5 mm Hg) and pulmonary vascular resistance (2.6 WU versus 2.3 WU; P<0.001 for both). Before propensity matching, the incidence of severe early RHF was higher among patients on PDE5i than in controls (29.4% versus 23.1%; unadjusted odds ratio (OR), 1.32; 95% CI, 1.17-1.50). This association persisted after propensity matching (PDE5i, 28.9% versus control 23.7%; OR, 1.31; 95% CI, 1.09-1.57), driven by a higher incidence of prolonged inotropic support. Similar results were observed across a wide range of subgroups stratified by markers of pulmonary vascular disease and RV dysfunction. Conclusions Patients treated with preoperative PDE5i had markers of increased RV afterload and HF severity compared to unmatched controls. Even after propensity matching, patients receiving preimplant PDE5i therapy had higher rates of post-LVAD RHF.

Vasoplegic syndrome in cardiac surgery: Definitions, pathophysiology, diagnostic approach and management

Vasoplegic syndrome is a state of vasopressor resistant systemic vasodilation in the presence of a normal cardiac output. Its definition, pathophysiology, risk factors, diagnosis and therapeutic approach will be reviewed in this paper. It occurs frequently during cardiac surgery and is associated with high morbidity and mortality. A search in the LILACS, MEDLINE, and GOOGLE SCHOLAR databases was conducted to find the most relevant papers during the last 18 years. Prompt identification and diagnosis of patients at risk must be undertaken in order to implement an optimal therapeutic approach. This latter includes early treatment with vasopressors with different mechanisms of action.

Management of primary graft failure after heart transplantation: Preoperative risks, perioperative events, and postoperative decisions

Primary graft failure (PGF) after heart transplantation (HT) is a devastating and unexpected event characterized by failure of the graft to adequately support recipient circulation necessitating high doses of vasopressors and inotropes and/or temporary mechanical circulatory support. Although it represents an increasingly common event in the current era, there remains a high degree of variability in prevalence, reported risk factors, and approach to this clinical entity. The purpose of the current review is to highlight preoperative considerations including known incidence and risk factors, perioperative issues involving the identification and management of PGF, and postoperative decisions related to weaning of mechanical circulatory support and titration of immunosuppressive therapy. Lastly, we highlight future directions in PGF research, involving basic and translational research, that have the potential to uncover novel strategies of risk stratification and treatment. CASE: Our patient is a 53-year-old man with end-stage non-ischemic dilated cardiomyopathy complicated by ventricular tachycardia (VT), post-capillary pulmonary hypertension, and renal insufficiency. After progressing to NYHA Class IV symptoms, he underwent implantation of a durable left ventricular assist device (LVAD) as bridge to transplant (BTT). On device support, he developed recurrent VT resulting in multiple defibrillator discharges and hospital admission for intravenous anti-arrhythmic therapy. He is subsequently upgraded to a higher status on the waiting list. A suitable donor is identified, with an appropriate predicted heart mass and an anticipated ischemic time of <4 hours. He is taken to the operating room, where at the time of anesthesia induction he develops vasodilatory shock, requiring high-dose vasopressors, and cardiopulmonary bypass (CPB) support for dissection. After surgical anastomosis, cross clamp removal and reperfusion, graft function is extremely poor, there is significant bradycardia requiring pacing, and the patient is unable to be weaned successfully from CPB. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is initiated, and the patient is transferred to the intensive care unit. Retrospective flow crossmatch is negative. This patient is suffering from severe primary graft failure.

The triple variable index combines information generated over time from common monitoring variables to identify patients expressing distinct patterns of intraoperative physiology

Background

Mean arterial pressure (MAP), bispectral index (BIS), and minimum alveolar concentration (MAC) represent valuable, yet dynamic intraoperative monitoring variables. They provide information related to poor outcomes when considered together, however their collective behavior across time has not been characterized.

Methods

We have developed the Triple Variable Index (TVI), a composite variable representing the sum of z-scores from MAP, BIS, and MAC values that occur together during surgery. We generated a TVI expression profile, defined as the sequential TVI values expressed across time, for each surgery where concurrent MAP, BIS, and MAC monitoring occurred in an adult patient (≥18 years) at the University of Pittsburgh Medical Center between January and July 2014 (n = 5296). Patterns of TVI expression were identified using k-means clustering and compared across numerous patient, procedure, and outcome characteristics. TVI and the triple low state were compared as prediction models for 30-day postoperative mortality.

Results

The median frequency MAP, BIS, and MAC were recorded was one measurement every 3, 5, and 5 min. Three expression patterns were identified: elevated, mixed, and depressed. The elevated pattern displayed the highest average MAP, BIS, and MAC values (86.5 mmHg, 45.3, and 0.98, respectively), while the depressed pattern displayed the lowest values (76.6 mmHg, 38.0, 0.66). Patterns (elevated, mixed, depressed) were distinct across the following characteristics: average patient age (52, 53, 54 years), American Society of Anesthesiologists Physical Status 4 (6.7, 16.1, 27.3%) and 5 (0.1, 0.6, 1.6%) categories, cardiac (2.2, 6.5, 16.1%) and emergent (5.8, 10.5, 12.8%) surgery, cardiopulmonary bypass use (0.3, 2.6, 9.8%), intraoperative medication administration including etomidate (3.0, 7.3, 12.6%), hydromorphone (47.6, 26.3, 25.2%), ketamine (11.2, 4.6, 3.0%), dexmedetomidine (18.4, 16.6, 13.6%), phenylephrine (74.0, 74.8, 83.0), epinephrine (2.0, 6.0, 18.0%), norepinephrine (2.4, 7.5, 21.2%), vasopressin (3.4, 7.6, 21.0%), succinylcholine (74.0, 69.0, 61.9%), intraoperative hypotension (28.8, 33.0, 52.3%) and the triple low state (9.4, 30.3, 80.0%) exposure, and 30-day postoperative mortality (0.8, 2.7, 5.6%). TVI was a better predictor of patients that died or survived in the 30 days following surgery compared to cumulative triple low state exposure (AUC 0.68 versus 0.62, p < 0.05).

Conclusions

Surgeries that share similar patterns of TVI expression display distinct patient, procedure, and outcome characteristics.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0660-9) contains supplementary material, which is available to authorized users.

Perioperative Management of the Cardiac Transplant Recipient

Management of the cardiac transplant recipient includes careful titration of inotropes and vasopressors. Recipient pulmonary hypertension and ventilatory status must be optimized to prevent allograft right ventricular failure. Vasoplegia, coagulopathy, arrhythmias, and renal dysfunction also require careful management to achieve an optimal outcome. Primary graft dysfunction (PGD) can be an ominous problem after cardiac transplantation. Although mild degrees of PGD may be managed medically, mechanical circulatory support with extracorporeal membrane oxygenation or temporary ventricular assist devices may be required. Retransplantation may be necessary in some cases.