Definition

•  Anaphylaxis – acute onset skin, mucosal or GI involvement w/ at least 1 of the following: Respiratory distress, hypotension, end-organ Dysfxn

History

•  Exposures: Nuts, shellfish, medication (abx, NSAIDs, iodine contrast), insect, ACEI (angioedema), PMH: Hereditary angioedema

•  Sx: SOB, swelling of tongue/throat, hoarseness, hives, N/V, abdominal cramps, syncope

Findings

•  Urticaria, conjunctival injection, diffuse erythema, swelling (face, tongue, mouth), hoarseness, drooling, stridor, ↓ BP

Evaluation

•  Assess airway, potential need for intubation; IV access & fluid resuscitation for anaphylactic shock

•  H1 + H2 > H1 antagonist alone for urticaria (NEJM 2004;351:2203)

•  IM vs. SC epinephrine: IM preferred → more rapid absorption (J Allergy Clin Immunol 2001;108:871)

•  Epinephrine & cardiac dz: Pt should be on monitor; CAD = relat. CI

•  Glucocorticoids may prevent recurrence or extended event, though evidence inconclusive

Disposition

•  Home w/ 2 epi-pens (one home, one w/ pt)

•  Pts w/ either (1) local rxns w/o airway involvement or (2) generalized rxn + presented to ED hours after exposure

•  Admit to Obs unit/floor: Any pt requiring epinephrine

•  Admit to ICU: Severe anaphylactic rxn, airway compromise

Pearls

•  ACEI can cause angioedema at any time, independent of length of use

•  PCN allergy: IgE-mediated allergy confers low (∼1%) risk of cross-reactivity w/ cephalosporins; however, avoid if rxn is severe (NEJM 2006;354:601)

ONCOLOGIC EMERGENCIES

NEUTROPENIC FEVER

Approach

•  Initiate access, IVFs, abx, & tx of sepsis as early as possible. Pts can deteriorate quickly.

Definition

•  Single temp >38.3°C or temp >38°C for 1 h + ANC <500, or <1000 + predicted drop <500, or functionally neutropenic (eg, AML)

•  Pts may experience rapid clinical deterioration w/ few presenting signs of inflammation

History

•  Date of fever onset, date of cytotoxic therapy (ANC nadir ∼10–14 d after chemo)

Findings

•  Examine skin, mouth, lung, abdomen, catheter/surgical sites, perirectal area (DRE)

Evaluation

•  CBC w/ differential, Chem 7, LFTs, coags, UA/urine cx, blood cx (at least 2 + any catheter port if present), ±CXR

•  ±Additional labs: Coags, culture (stool/sputum/peritoneal/CSF)

•  Imaging: Consider imaging of chest, abdomen/pelvis, sinuses, brain

Treatment

•  Empiric abx → low risk: Ciprofloxacin + (amoxicillin + clavulanate)

•  Empiric abx → high risk: AFTER cx are drawn, cover for resistant Pseudomonas:

•  Monotherapy: Ceftazidime, cefepime, or carbapenem (except ertapenem)

•  Combination (synergy against GNRs): Aminoglycoside + antipseudomonal PCN or any of the monotherapy drugs

•  Vancomycin: For catheter-related infxn, MRSA colonization, ↓ BP

•  PCN-allergic → levofloxacin + aztreonam or aminoglycoside

•  Antivirals: Acyclovir (if skin lesions c/w herpes/VZV)

Disposition

•  Low threshold to admit all pts w/ neutropenic fever

Pearls

•  ≥50% pts w/ neutropenic fever have occult infection & ∼60–70% are gram+ (Clin Infect Dis 2002;34:730)

•  Atypical organisms, meningitis are rare

TUMOR LYSIS SYNDROME (Oncology 2011;25(4):378)

Approach

•  Obtain ECG immediately (look for signs ↑ K), & put on cardiac monitor

Definition

•  Rapid destruction neoplastic cells → release of intracellular uric acid, K, PO₄

•  Defined as ≥2 of abnl serum values (>25% ↑ K, ↑ PO₄, ↓ Ca) w/i 3 d before or 7 d after the start of chemotherapy & ≥1 of renal failure (GFR ≤ 60), cardiac arrhythmia, or sz

•  Typically 48–72 h after starting cytotoxic cancer tx, a/w large, rapidly proliferating, tx-responsive tumors (esp acute leukemia, NHL, Burkitt)

History

•  N/V, lethargy, edema, CHF, hematuria, cardiac dysrhythmia, sz, muscle cramps, tetany, syncope, sudden death

Evaluation

•  Chem 7, Ca, PO₄, uric acid, BUN/Cr, LDH, UA (urine pH) → ↑ uric acid, ↑ K, ↑ PO₄, ↓ Ca; uric acid must be drawn on ice

Treatment

•  Treat ↑ K/↑ PO₄ & symptomatic ↓ Ca

•  IVFs/hydration to maintain UOP > 100 mL/h: Pts typically have ↓ vascular volume

•  Isotonic sodium bicarbonate → urine alkalinization → prevents renal precipitation of uric acid

•  Allopurinol

•  Rasburicase: In consultation w/ oncology → promotes metabolism of uric acid, may reduce need for dialysis, do not give concomitant allopurinol (J Clin Oncol 2001;19:697)

•  HD: If persistent ↑ K, severe acidosis, volume overload, uremia, severe ↑ PO₄ or ↓ Ca

Disposition

•  Admit (floor vs. ICU, depending on severity)

SICKLE CELL DISEASE

(BMJ 2008;337:a1397)
Approach

•  Start O₂ if pt hypoxemic or having pain

•  Pain medication: Start early, check w/ hematologist for dose

•  Abx: If infection is suspected, particularly w/ fever (many pts are functionally asplenic)

Definition

•  Pathophysiology: Recessive β-globin mutation → structurally abnl HbS → deoxygenate form polymerizes → RBC sickles → hemolysis/microvascular occlusion

•  Anemia: Chronic (hemolysis 2/2 sickling), acute (parvovirus B19, splenic sequestration)

•  Microvascular occlusion: Pain crisis, acute chest syndrome, stroke, splenic sequestration, renal necrosis, aseptic necrosis, priapism

•  Infection: Sepsis from encapsulated organisms (S. pneumoniae, N. meningitidis, H. influenzae) after splenic infarction & osteomyelitis (Salmonella, S. aureus)

History

•  CP, SOB, bone pain (back, extremities)

Findings

•  Bone tenderness, tachypnea, ±fever, r/o stroke, priapism

Evaluation

•  CBC w/ differential (compare to baseline), chemistries, reticulocyte count (if concern for aplastic crisis or severe hemolysis), LFTs, bilirubin

•  CP crisis: CXR (consolidation), ABG, ECG

•  Consider other x-ray/MRI (osteomyelitis), CTA chest (PE); CTA/MRI (stroke) prn

Treatment

Acute

•  ↓ sickling: O₂, IVFs, analgesia w/ opiates (contact hematologist for doses)

•  Treat infection w/ abx

•  Transfusion for aplastic anemia, splenic sequestration, priapism

•  Exchange transfusion: For acute stroke, severe acute chest syndrome

Chronic

•  Hydroxyurea: ↑ HbF & ↓ pain crises, frequency & duration of hospitalizations, & risk of acute chest syndrome (NEJM 1995;1332:1317), ↓ mortality (NEJM 2003;1289:1645)

Disposition

•  Home: If pain is well controlled

•  Admit: Concern for sepsis, acute chest, or hemolytic crisis

Pearl

•  Acute chest syndrome: Vaso-occlusion of pulmonary vasculature → pulmonary infarct, consolidation, PNA that resembles ARDS

ABNORMAL BLEEDING: PLATELET DISORDERS AND COAGULOPATHY

Approach

•  Stabilize pt (ABCs, IV access/monitor) if necessary

•  Differentiate cause of bleeding → PLT vs. coagulation abnlty

•  Consult hematology for any pt w/ severe bleeding & known or suspected bleeding d/o

Findings

•  Purpura

•  Nonpalpable: TCP, PLT Dysfxn, DIC, TTP, cholesterol/fat emboli, scurvy, trauma

•  Palpable: Vasculitis, HSP, PAN, RMSF, meningococcemia, bacterial endocarditis

Evaluation

•  CBC w/ differential, Chem 7, coags; consider LFTs, peripheral blood smear, DIC panel (fibrinogen, D-dimer, LDH, haptoglobin)

THROMBOCYTOPENIA (TCP) AND PLATELET DYSFUNCTION

Approach

•  Isolated TCP: ITP, immune, medications, infection

•  TCP + abnl CBC/smear: DIC, HUS, TTP, aplastic anemia, malignancy

Definition

•  By PLT count

•  <150000: TCP

•  >100000: No ↑ risk bleeding

•  <50000: Risk of minor bleeding, increased bleeding in trauma

•  <20000: Risk of spontaneous bleeding

•  <10000: Risk of severe bleeding such as GIB, ICH

History

•  PMH (EtOHism, HIV, malignancy, pregnant, meds), infection

Findings

•  Splenomegaly, LAD, bleeding

Evaluation

•  CBC w/ differential; consider the following:

•  Hemolysis w/u: Reticulocyte count, LDH, haptoglobin, bilirubin, peripheral blood smear, coags, fibrinogen, D-dimer, direct Coombs

IMMUNE THROMBOCYTOPENIA (Blood 2010;115(2):168)

Approach

•  This is a Dx of exclusion → w/u other etiologies beforehand (TTP/HUS, other immune-mediated dz, drugs, HIV, HCV)

•  Consider myelodysplasia in pts >60 y/o

Definition

•  Immune Ab-mediated destruction of PLTs (PLT count <100 × 10⁹/L) subdivided into primary (no known cause) & secondary (to viruses, drugs, autoimmune dzs, vaccines)

History

•  Gradual onset of petechiae, epistaxis, easy bruising, menorrhagia, hematuria, GIB, recent viral illness

Evaluation

•  CBC w/ differential, peripheral blood smear, T + S, Ig levels, HIV/HCV, H. pylori, direct antiglobulin

Treatment

•  Rarely indicated for PLTs >50 × 10⁹/L unless increased risk for bleeding or surgery

•  Consider hematology consult in adults: Often require tx 2/2 very low PLTs

•  Steroids: Prednisone 0.5–2 mg/kg/d w/ taper → short-term utility; give methylprednisolone 1 g/d IV if active bleeding

•  If active bleeding or unresponsive to steroids, Anti-Rh(D) Ig: 75 mcg/kg/d IV → for Rh(D)+ pts; IVIG: 1 g/kg/d IV × 1–2 d

•  PLT transfusion for bleeding or very low PLTs → use w/ IVIG or Anti-Rh(D) Ig

•  Children: Manage mild cases expectantly, treat if PLTs <20000 or active bleeding

•  Steroids: Prednisone 4 mg/kg/d PO × 4 d

•  Anti-Rh(D) Ig: 75 mcg/kg IV × 2 d

•  IVIG: 0.8–1 g/kg IV × 1 dose

Disposition

•  Home: If no active bleeding, PLTs >20000

•  Admit: Any pt w/ PLTs <20000 &/or active bleeding

Pearls

•  Though 50–75% pts respond to steroids, <20% have sustained remission after taper

•  ∼50% ITP occurs in children

HEPARIN-INDUCED THROMBOCYTOPENIA (HIT) (Chest 2012;141(2 suppl):e495S)

Definition

•  Either direct (type I) or Ab-mediated (type II) PLT activation → heparin stimulates formation of IgG → binds to PF4 & heparin on PLT surface → PLT-derived microparticles form & promote thrombin release → ↑ thrombosis

Diagnosis

•  PLTs: <150000 or ↓ 30–50% from baseline

•  Thrombosis in all vascular beds: eg. PE, DVT, limb ischemia, stroke, MI → up to 50% pts

•  Increased heparin resistance

•  HIT Ab (PF4-heparin ELISA): ↓ PPV (10–93%) & ↑ NPV (>95%), so send only if intermediate/high PreTP ± confirm w/ PLT aggregation test

History

•  Low PLTs ± thrombosis, 5–10 d after starting heparin (rarely causes bleeding), more rapid onset less common but a/w more recent heparin exposure (<30 d)

Treatment (NEJM 2006;355:809)

•  STOP heparin + any device/flush that contains heparin

•  Consult hematology

•  If on therapeutic heparin: Switch to alternative (argatroban, bivalirudin, lepirudin)

•  Avoid PLT transfusions unless bleeding or high risk of bleeding

•  Future use of heparin (NEJM 2001;344:1286): Risk may be low if negative for PF4 Ab >100 d after Dx

Disposition

•  Admit

HEMOLYTIC-UREMIC SYNDROME (HUS) AND THROMBOTIC THROMBOCYTOPENIC PURPURA (TTP) (J Intensive Care Med 2007;22(2):82; Br J Haematol 2012;158(3):323; NEJM 2006;354:1927)

Definition

•  Systemic (TTP) or intrarenal (HUS) vascular occlusive d/o via PLT aggregation → MAHA (TCP/hemolysis), though their underlying cause is different

•  A/w ADAMTS-13 deficiency → inability to cleave vWF → microthrombi

Differential

•  Sepsis, DIC, HELLP

History

•  HUS:

•  HUS triad: MAHA, TCP, renal failure

•  Children w/ bloody diarrhea → 2/2 enterohemorrhagic E. coli Shiga toxin

•  TTP:

•  TTP pentad (uncommon): MAHA, TCP, renal failure, AMS, fever

•  Adults → often idiopathic or 2/2 drugs (ie, clopidogrel, chemotherapy, quinidine)

Evaluation

•  CBC w/ differential, Chem 7, peripheral blood smear, coags, LFTs, LDH, haptoglobin, fibrinogen, D-dimer, UA

•  Dx: MAHA + TCP (same for HUS or TTP)

•  MAHA: Evidenced by schistocytes, ↑ LDH, ↑ indirect bilirubin, ↑ Cr (HUS > TTP), ↓ haptoglobin

Treatment

•  Consult hematology, consider renal consult early

•  TTP:

•  Plasma exchange: All pts w/ TTP → ↑ survival @ 6 mo (NEJM 1991;325:393)

•  FFP: If there is a delay to plasma exchange

•  Steroids: Prednisone 1–2 mg/kg/d, methylprednisolone 1 g/d max 3 d (no well-designed studies evaluating efficacy)

•  Low-dose aspirin when PLTs recover (anecdotal evidence), folate supplementation

•  HUS: Mainly supportive ± dialysis

Disposition

•  Admit

Pearls

•  Do not give PLTs → ↑ microvascular thrombosis

•  Mortality of TTP is up to 90% w/o tx (NEJM 2006;354:1927), while HUS often resolves w/o tx

VON WILLEBRAND’S DISEASE (vWD) (NEJM 2004;351:683; Haemophilia 2008;14(2):171)

Definition

•  vWF defect/↓: A substrate for PLT aggregation/carrier of factor VIII

•  Autosomal dominant or recessive, or acquired (eg, malignancy, meds)

History

•  Can present like TCP &/or coagulopathy → role w/ PLTs & factor VIII

•  Mucocutaneous bleeding & bleeding after surgery, menorrhagia, easy bruising, epistaxis, rarely hemarthrosis, hematoma (severe forms)

Evaluation

•  CBC w/ differential (↓ PLTs), Chem 7, coags (↑ PTT), ↓ factor VIII, ↓ vWF: Ag, ↓ vWF activity

Treatment

•  Desmopressin (DDAVP): Efficacy is variable, causes endothelial release of vWF

•  vWF replacement: Via cryoprecipitate (requires up to 8–12 bags), plasma-derived vWF/factor VIII concentrate (Humate-P), or recombinant vWF, w/ antifibrinolytic amino acids (as adjunct)

Disposition

•  Depends on pt’s presentation, severity of vWD, & location of bleeding

Pearl

•  Most common inherited bleeding d/o

COAGULOPATHY

Approach

•  Differentiate inherited vs. acquired, & tx underlying causes

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