Symmetrical Peripheral Gangrene: Mechanisms for Limb Loss in the ICU in Patients With Retained Pulses

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.

Foot gangrene following Tagraxofusp treatment for blastic plasmacytoid dendritic cell neoplasm: Case report

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy. It is associated with poor prognosis and heterogenous presentation. The CD123-directed cytotoxin, Tagraxofusp, is a targeted therapy for BPDCN. Here, we report an 81-year-old female diagnosed with BPDCN. The patient was treated with Tagraxofusp and underwent a remarkably long remission (>20 months) without stem-cell transplantation. She, however, experienced blue toe syndrome and left foot gangrene. We postulate that these previously unreported side effects were caused by microembolization. Characterization of the incidence of thrombo- and microembolizations in such a context, as well as prophylactic management options, are warranted.

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.

The initial resuscitation of septic shock

Septic shock is the most severe form of sepsis, characterized by (a) persistent hypotension despite fluid resuscitation and (b) the presence of tissue hypoperfusion. Delays in the diagnosis and initiation of treatment of septic shock is associated with increasing risk for mortality. Early and effective fluid resuscitation and vasopressor administration play a crucial role in maintaining tissue perfusion in septic shock patients. A low diastolic arterial pressure (DAP) correlates with severity of arteriolar vasodilation, compromises left ventricle oxygen supply and can be used for identifying septic shock patients that would potentially benefit from earlier vasopressor therapy. Controversy currently exists as to the balance of fluids and vasopressors to maintain target mean arterial pressure. The aim of this article is to review the rationale for fluid resuscitation and vasopressor therapy and the importance of both mean and diastolic blood pressure during the initial resuscitation of the septic shock. We relate our personal prescription of balancing fluids and vasopressors in the resuscitation of septic shock.

Sepsis-induced digital ischaemia in a professional pianist, in the absence of vasopressors

Peripheral limb ischaemia and gangrene are devastating complications of pneumococcal sepsis. We report a 43-year-old professional pianist who presented with early sepsis and rapid development of this syndrome. No vasopressor medication was ever administered. We urgently reviewed the medical literature on a range of therapies recommended by consulting teams, to ensure he received optimal care. Based on our review and on feedback from the patient himself, we gained valuable insights into this illness and the merits of selected treatment options. His fingers ultimately recovered their function, intact, although several toes were later amputated. More recently published reviews postulate that imbalances in coagulation factors and natural anticoagulants occur as a result of disseminated intravascular coagulopathy and 'shock liver' in the sepsis syndrome, leading to microcirculatory thromboses. We submit this report as we believe it supports this hypothesis and adds further valuable information. We hope our observations will assist other critical care clinicians confronting this serious condition.

Heparin-induced thrombocytopenia-associated thrombosis: from arterial to venous to venous limb gangrene

Heparin-induced thrombocytopenia (HIT) is an acquired immune-mediated hypercoagulability state that is strongly associated with thrombosis. During the 1970s and 1980s, the prevailing concept was that HIT was associated only with arterial thrombosis, through its unique pathogenesis via heparin-dependent, platelet-activating IgG antibodies. However, in 1990, when I began to encounter HIT in my clinical practice, I found that most such patients developed symptomatic venous thrombosis. This historical sketch summarizes some of the research that challenged the dogma of HIT being a mainly arterial prothrombotic disorder. Two studies - one a substudy of a randomized trial of post-orthopedic surgery thromboprophylaxis, and the second a retrospective five-hospital analysis of consecutive patients with positive test results for HIT antibodies - showed a marked predominance of venous over arterial thrombosis complicating HIT (~ 4 : 1). By the end of the 1990s, an even more dramatic manifestation of HIT-associated venous thrombosis was recognized: venous limb gangrene. Here, ischemic limb necrosis occurs despite palpable arterial pulses, as a result of both macrovascular and microvascular venous thrombosis. The surprising explanation was natural anticoagulant impairment (severe depletion of protein C, a vitamin K-dependent anticoagulant) resulting from treatment of HIT-associated deep vein thrombosis with warfarin (vitamin K antagonist). These insights from HIT research helped to elucidate the pathogenesis of ischemic limb losses in other intense non-HIT hypercoagulability states, including warfarin-associated venous limb gangrene complicating cancer-associated hypercoagulability, and symmetrical peripheral gangrene complicating disseminated intravascular coagulation of critical illness, in which proximate 'shock liver' helps to explain the profound failure of natural anticoagulant systems (protein C; antithrombin) in predisposing to peripheral limb microthrombosis in circulatory shock.