Ischemic limb necrosis in septic shock: What is the role of high-dose vasopressor therapy?

Limb Ischemic Necrosis Secondary to Microvascular Thrombosis: A Brief Historical Review

Ischemic limb injury can be broadly classified into arterial (absent pulses) and venous/microvascular (detectable pulses); the latter can be divided into two overlapping disorders-venous limb gangrene (VLG) and symmetrical peripheral gangrene (SPG). Both VLG and SPG feature predominant acral (distal) extremity ischemic necrosis, although in some instances, concomitant nonacral ischemia/skin necrosis occurs. Historically, for coagulopathic disorders with prominent nonacral ischemic necrosis, clinician-scientists implicated depletion of natural anticoagulants, especially involving the protein C (PC) system. This historical review traces the recognition of natural anticoagulant depletion as a key feature of nonacral ischemic syndromes, such as classic warfarin-induced skin necrosis, neonatal purpura fulminans (PF), and meningococcemia-associated PF. However, only after several decades was it recognized that natural anticoagulant depletion is also a key feature of predominantly acral ischemic microthrombosis syndromes-VLG and SPG-even when accompanying nonacral thrombosis is not present. These acquired acral limb ischemic syndromes typically involve the triad of (a) disseminated intravascular coagulation, (b) natural anticoagulant depletion, and (c) a localizing explanation for microthrombosis occurring in one or more limbs, either deep vein thrombosis (helping to explain VLG) or circulatory shock (helping to explain SPG). In most cases of VLG or SPG there are one or more events that exacerbate natural anticoagulant depletion, such as warfarin therapy (e.g., warfarin-associated VLG complicating heparin-induced thrombocytopenia or cancer hypercoagulability) or acute ischemic hepatitis ("shock liver") as a proximate factor predisposing to severe depletion of hepatically synthesized natural anticoagulants (PC, antithrombin) in the setting of circulatory shock.

Deranged Balance of Hemostasis and Fibrinolysis in Disseminated Intravascular Coagulation: Assessment and Relevance in Different Clinical Settings

The disruption of hemostasis/fibrinolysis balance leads to disseminated intravascular coagulation, manifested clinically by bleeding or thrombosis, and multiorgan failure. This study reviews hemostatic assessment and therapeutic strategies that restore this balance in critically ill patients.

Limb Necrosis in the Setting of Vasopressor Use

BACKGROUND

It remains poorly understood why only some hemodynamically unstable patients who receive aggressive treatment with vasopressor medications develop limb necrosis.

OBJECTIVE

To determine the incidence of limb necrosis and the factors associated with it following high-dose vasopressor therapy.

METHODS

A retrospective case-control medical records review was performed of patients aged 18 to 89 years who received vasopressor therapy between 2012 and 2021 in a single academic medical center. The study population was stratified by the development of limb necrosis following vasopressor use. Patients who experienced necrosis were compared with age- and sex-matched controls who did not experience necrosis. Demographic information, comorbidities, and medication details were recorded.

RESULTS

The incidence of limb necrosis following vasopressor administration was 0.25%. Neither baseline demographics nor medical comorbidities differed significantly between groups. Necrosis was present in the same limb as the arterial catheter most often for femoral catheters. The vasopressor dose administered was significantly higher in the necrosis group than in the control group for ephedrine (P = .02) but not for the other agents. The duration of therapy was significantly longer in the necrosis group than in the control group for norepinephrine (P = .001), epinephrine (P = .04), and ephedrine (P = .01). The duration of vasopressin administration did not differ significantly between groups.

CONCLUSION

The findings of this study suggest that medication-specific factors, rather than patient and disease characteristics, should guide clinical management of necrosis in the setting of vasopressor administration.

Managing sepsis and septic shock in an endothelial glycocalyx-friendly way: from the viewpoint of surviving sepsis campaign guidelines

Maintaining tissue perfusion in sepsis depends on vascular integrity provided by the endothelial glycocalyx, the critical layer covering the luminal surface of blood vessels. The glycocalyx is composed of proteoglycans, glycosaminoglycans, and functional plasma proteins that are critical for antithrombogenicity, regulating tone, controlling permeability, and reducing endothelial interactions with leukocytes and platelets. Degradation of the glycocalyx in sepsis is substantial due to thromboinflammation, and treatments for sepsis and septic shock may exacerbate endotheliopathy via additional glycocalyx injury. As a result, therapeutic strategies aimed at preserving glycocalyx integrity should be considered, including modifications in fluid volume resuscitation, minimizing catecholamine use, controlling hyperglycemia, and potential use of corticosteroids and anticoagulants. In this review, we explore treatment strategies aligned with the recommendations outlined in the Surviving Sepsis Campaign Guidelines 2021 with a special emphasis on evidence regarding glycocalyx protection.

Management of Vasoplegic Shock in the Cardiovascular Intensive Care Unit after Cardiac Surgery

Vasoplegic shock after cardiac surgery is characterized by hypotension, a high cardiac output, and vasodilation. Much of the understanding of this pathologic state is informed by the understanding of septic shock. Adverse outcomes and mortality are increased with vasoplegic shock. Early recognition and a systematic approach to its management are critical. The need for vasopressors to sustain an adequate blood pressure as well as pharmacologic adjuncts to mitigate the inflammatory inciting process are necessary. The rationale behind vasopressor escalation and consideration of adjuncts are discussed.

Vasopressin-Induced Gangrene of the Bilateral Foot Digits and Right Index Finger Managed With Platelet-Rich Plasma Treatment

Bilateral foot digit gangrene generated by vasopressin is a serious complication for which management and treatment choices are extremely difficult. This case report presents a case of vasopressin-induced gangrene that was successfully treated with platelet-rich plasma (PRP) infiltration. A 20-year-old female patient came with a history of vasopressin treatment, causing bilateral foot digit gangrene and increasing necrosis. The patient's health quickly declined, and conventional care techniques had no effect on enhancing tissue perfusion or stopping the gangrene from getting worse. In our study, we have chosen to use PRP infiltration as an experimental therapeutic technique in light of the restricted choices available. This case study demonstrates the possibility of PRP infiltration as a cutting-edge and effective treatment for vasopressin-induced bilateral foot digit gangrene. The potential of PRP to stimulate angiogenesis, tissue regeneration, and wound healing is essential for optimizing the patient's results. For vasopressin-induced gangrene, more studies are required to evaluate the efficacy of PRP infiltration as a common therapy approach. This case study highlights the important role that PRP infiltration plays in enhancing tissue perfusion, stopping the advancement of necrosis, and promoting recovery.

An Uncommon Presentation of Vasopressin-Induced Purpura Fulminans

Purpura fulminans (PF) is a rarely encountered rapidly evolving dermatological manifestation of ischemia, particularly in critically ill patients. Considered one of the very few dermatological emergencies, it has high mortality rate where patients often succumb to the illness. It can manifest in three forms: neonatal, idiopathic, and the more commonly infectious variety, which can be secondary to mostly bacterial and rarely viral etiology. It is also reported to be highly associated with disseminated intravascular coagulation (DIC), heparin-induced thrombocytopenia (HIT), and acute hepatic failure (AHF). Hereditary or acquired deficiency of protein C and dysregulation of the coagulation cascade, mainly protein C-thrombomodulin, has been implicated in the pathogenesis. We present a 55-year-old male admitted to the intensive care unit for diabetic ketoacidosis (DKA) and septic shock. Along with initiating management protocol for DKA and broad-spectrum antibiotics, he was initially started on norepinephrine for septic shock. Because of persistent refractory septic shock, he was subsequently initiated on phenylephrine and vasopressin to maintain adequate perfusion. The following day, he was found to have sharply demarcated blackish non-blanching discoloration on bilateral knees, lower limbs, and scrotum, sparing the acral regions. This cutaneous manifestation persisted throughout his hospital course, although it improved after discontinuation of vasopressin while continuing with other pressors. Vasopressin has been implicated in a few instances of skin necrosis; however, PF has rarely been documented and never within 1 day like ours. This case demonstrates a unique development of PF likely from vasopressin after ruling out the diagnoses of DIC, HIT, thrombotic thrombocytopenic purpura, and AHF.

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.

Buttock Ischemia in Venoarterial Extracorporeal Membrane Oxygenation: A Case Series

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a bridging therapy for refractory cardiogenic shock, and limb ischemia is a concern with femoral cannulation. Because of the rich collateral pelvic circulatory supply, buttock ischemia is not common and is usually a complication after aneurysmal aortic repair or internal iliac artery embolization after pelvic trauma. Gluteal necrosis occurring as an extracorporeal membrane oxygenation complication has not been reported in the literature. In this case series, we report three patients with ischemic buttock after initiating VA-ECMO and discuss the risk factors and the clinical and radiological features supportive of the diagnosis. We review the gluteal and pelvic vascular anatomy, postulate how cannula size, ethnicity, catecholamines, and reversal of gluteal arterial flow contributed to this rare entity in our patients and explain how these findings have changed our institution's practice.

The Epidemiology of Extremity Threat and Amputation after Vasopressor-Dependent Sepsis

Rationale: Extremity threat and amputation after sepsis is a well-publicized and devastating event. However, there is a paucity of data about the epidemiology of extremity threat after sepsis onset. Objectives: To estimate the incidence of extremity threat with or without surgical amputation in community sepsis. Methods: Retrospective cohort study of adults with Sepsis-3 hospitalized at 14 academic and community sites from 2013 to 2017. Vasopressor-dependent sepsis was identified by administration of epinephrine, norepinephrine, phenylephrine, vasopressin, or dopamine for more than 1 hour during the 48 hours before to 24 hours after sepsis onset. Outcomes included the incidence of extremity threat, defined as acute onset ischemia, with or without amputation, in the 90 days after sepsis onset. The association between extremity threat, demographics, comorbid conditions, and time-varying sepsis treatments was evaluated using a Cox proportional hazards model. Results: Among 24,365 adults with sepsis, 12,060 (54%) were vasopressor dependent (mean ± standard deviation age, 64 ± 16 years; male, 6,548 [54%]; sequential organ failure assessment [SOFA], 10 ± 4). Of these, 231 (2%) patients had a threatened extremity with 26 undergoing 37 amputations, a risk of 2.2 (95% confidence interval [CI], 1.4-3.2) per 1,000, and 205 not undergoing amputation, a risk of 17.0 (95% CI, 14.8-19.5) per 1,000. Most amputations occurred in lower extremities (95%), a median (interquartile range) of 16 (6-40) days after sepsis onset. Compared with patients with no extremity threat, patients with threat had a higher SOFA score (11 ± 4 vs. 10 ± 4; P < 0.001), serum lactate (4.6 mmol/L [2.4-8.7] vs. 3.1 [1.7-6.0]; P < 0.001), and more bacteremia (n = 37 [37%] vs. n = 2,087 [26%]; P < 0.001) at sepsis onset. Peripheral vascular disease, congestive heart failure, SOFA score, and norepinephrine equivalents were significantly associated with extremity threat. Conclusions: The evaluation of a threatened extremity resulting in surgical amputation occurred in 2 per 1,000 patients with vasopressor-dependent sepsis.

Hirudotherapy for limb ischemia in the pediatric intensive care unit: A retrospective observational cohort

BACKGROUND

Acute limb ischemia due to microvascular malperfusion may be refractory to initial therapies. Medicinal leech therapy (hirudotherapy) has been attempted in plastic and reconstructive surgery to improve venous congestion in ischemic flaps; however, there are minimal reports related to ischemia secondary to arterial malperfusion. We evaluated a pediatric cohort from an academic intensive care unit with refractory limb ischemia in whom hirudotherapy was attempted to elucidate its use and outcomes.

METHOD

Institutional patient database was queried to identify pediatric patients (<18 years) who received hirudotherapy in the pediatric critical care unit and met inclusion/exclusion criteria. Patient charts were evaluated for indices including demographics, primary disease, coagulative status, vascular access, vasoactive medication dosing, bleeding, leech use, limb and mortality outcomes. Data was evaluated to identify trends or suspected impact on outcomes.

RESULTS

Hirudotherapy was used in 7 patients for limb ischemia, 5 with congenital heart disease, and 2 others with viremic shock. Time to leech application following recognition of ischemia averaged 3 days, with duration of use averaging 3.9 days. Five patients discontinued therapy due to bleeding. Mortality rate was 57%, all secondary to multiorgan failure. In 3 surviving patients, 4 of 5 treated limbs resulted in at minimum partial amputation. Vasoactive-inotropic score tended higher prior to leech application, suggesting a vasoconstrictive pathway for arterial malperfusion. No identifiable trends appeared associated with salvaged limb or adverse effects. Blood loss predictably increased with leech application, as did total transfusion requirement.

CONCLUSION

This case series establishes baseline data for use of hirudotherapy in critically ill children with acute limb ischemia caused by arterial malperfusion. Based on this retrospective cohort, we cannot recommend routine use of hirudotherapy for acute limb ischemia from arterial malperfusion in the pediatric intensive care unit. Application of leeches should be aligned with a protocol defining start and stop parameters, standardized leech utilization, and monitoring for adverse outcomes. Future study would benefit from consensus definitions of study outcomes, including perfusion recovery, tissue/limb salvage and bleeding manifestations. Additional prospective studies are needed prior to any standard or systematic recommendations for use.

An international survey of adherence to Surviving Sepsis Campaign Guidelines 2016 regarding fluid resuscitation and vasopressors in the initial management of septic shock

BACKGROUND

Our survey aimed to evaluate adherence to Surviving Sepsis Campaign (SSC) Guidelines 2016 among intensive care practitioners and to identify issues that remain controversial or lack clarity.

METHODS

Members of the European Society of Intensive Care Medicine (ESICM) were surveyed using an anonymous web-based survey written by an international group of experts. The primary outcome measure was the rate of adherence to specific recommendations. Secondary outcomes were to describe areas of controversy and lack of data and to associate specific practices with clinician characteristics.

RESULTS

Overall 820 questionnaires were completed. The SCC recommendations 2016 most adhered to were the choice of norepinephrine as first-line vasoactive drug (96.5%), vasopressor prescription based on therapeutic goal rather than dose (83.4%), targeting a specific mean arterial blood pressure during vasopressor use (77.9%), monitoring of blood pressure invasively (62.8%) and adding vasopressin or epinephrine as a second vasoactive agent (83.4%). We identified an internal conflict with regards to parallel versus sequential administration of fluids and vasoactive drugs and regional differences in practice that may be related to drug availabilities.

CONCLUSION

The use of vasopressors and fluid use in septic shock is largely compliant with current guidelines but several controversies should be addressed in future guideline iterations.

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.

The Roles of Coagulation Disorder and Microthrombosis in Sepsis: Pathophysiology, Diagnosis, and Treatment

The diagnostic criteria of overt disseminated intravascular coagulation (DIC) were established by the International Society on Thrombosis and Haemostasis (ISTH) in 2001. Since then, DIC has long been associated with adverse outcomes. However, recent advances in sepsis shed light on the role of coagulation disorders in the progression of sepsis. Currently, inflammation and coagulation are recognized as the two drivers that promote organ dysfunction in sepsis and septic shock. The ISTH has published new diagnostic criteria for improved management, namely sepsis-induced coagulopathy (SIC), in 2017. SIC is a pragmatic scoring system composed of platelet count, prothrombin time, and organ dysfunction score to detect the early-stage of sepsis-associated DIC. Since overt DIC represents an uncompensated coagulation disorder, a two-step approach using SIC and overt DIC criteria is a novel strategy to evaluate the severity and manage this challenging complication. Although there is no globally agreed on anticoagulant therapy for DIC, the Japanese Surviving Sepsis Campaign Guidelines 2020 recommend using antithrombin and recombinant thrombomodulin for sepsis associated DIC. Since research in this area has been previously reported, an international collaborative study is necessary to develop future diagnostic tools and treatment strategies.

Symmetrical peripheral gangrene in critical illness

Symmetrical peripheral gangrene (SPG) is a disabling complication that affects a small proportion of patients who survive critical illness. Its pathogenesis reflects profoundly disturbed procoagulant-anticoagulant balance in susceptible tissue beds secondary to circulatory shock (cardiogenic, septic). There is a characteristic SPG triad: (a) shock (hypotension, lactic acidemia, normoblastemia, multiple organ dysfunction), (b) disseminated intravascular coagulation (DIC), and (c) natural anticoagulant depletion (protein C, antithrombin). In recent years, risk factors for natural anticoagulant depletion have been identified, most notably acute ischemic hepatitis ("shock liver"), which is seen in at least 90% of patients who develop SPG. Moreover, there is a characteristic time interval (2-5 days, median 3 days) between the onset of shock/shock liver and the beginning of ischemic injury secondary to peripheral microthrombosis ("limb ischemia with pulses"), reflecting the time required to develop severe depletion in hepatically-synthesized natural anticoagulants. Other risk factors for natural anticoagulant depletion include chronic liver disease (e.g., cirrhosis) and, possibly, transfusion of colloids (albumin, high-dose immunoglobulin) lacking coagulation factors. A causal role for vasopressor therapy is unproven and is unlikely; this is because critically ill patients who develop SPG do so usually after at least 36-48 hours of vasopressor therapy, implicating a time-dependent pathophysiological mechanism. The most plausible explanation is a progressive time-dependent decline in key natural anticoagulant factors, reflecting ongoing DIC ("consumption"), proximate liver disease whether acute or chronic ("impaired production"), and colloid administration ("hemodilution"). Given these evolving concepts of pathogenesis, a rationale approach to prevention/treatment of SPG can be developed.

Proposal of the Definition for COVID-19-Associated Coagulopathy

Thrombotic events are common complications in COVID-19 patients that include both thrombus formation in large vessels and the microvasculature of the lung and other organs. COVID-19-associated coagulopathy (CAC) and disseminated intravascular coagulation (DIC) have similarities and differences, and whether CAC is a form of DIC is the subject of debate. Reported mechanisms of CAC include activated coagulation, endotheliopathy, up-regulated innate and adaptive immunity, and activated complement system. Although the clinical features and laboratory findings of CAC and DIC seem different, there are fundamental similarities that should be considered. Basically, the pathological findings of COVID-19 fall within the scope of the definition of DIC, i.e., systemic activation of coagulation caused by or resulting from the microvascular damage. Therefore, we suggest that although CAC differs from usual infection-associated DIC, its various features indicate that it can be considered a thrombotic phenotype DIC. This review summarizes the current knowledge about CAC including differences and similarities with sepsis-associated DIC.

Heparin Induced Thrombocytopenia for the Perioperative and Critical Care Clinician

Purpose of Review

This review will illustrate the importance of heparin-induced thrombocytopenia in the intraoperative and critical care settings.

Recent Findings

Heparin-induced thrombocytopenia (HIT) occurs more frequently in surgical patients compared with medical patients due to the inflammatory release of platelet factor 4 and perioperative heparin exposure. Recognition of this disease requires a high index of suspicion. Diagnostic tools and therapeutic strategies have been expanded and refined in recent years.

Summary

HIT is a condition where antibodies against the heparin/platelet factor 4 complex interact with platelet receptors to promote platelet activation, aggregation, and thrombus formation. Our review will focus on intraoperative and postoperative considerations related to HIT to help the clinician better manage this rare but often devastating hypercoagulable disease process.