General Flashcards
Discuss the definition and diagnostic criteria for anaphylaxis
- is severe, hypersensitivity reaction that is rapid in onset and characterized by life-threatening airway, breathing and/or circulatory problems and associated skin and mucosal changes
Diagnostic Criteria (one of the following) - Acute onset of skin and/or mucosal involvement with one of respiratory compromise or reduced BP or associated end organ damage
- two or more following exposure to likely allergen
- involvement of mucosal tissue
- respiratory compromise
- reduced BP or associated symptoms
- gastrointestinal symptoms
- reduced BP after exposure to a known allergen
Discuss the pathophysiology of anaphylaxis
First exposure have activation of B cells producing IgE antibodies -> IgE bind to mast cells -> re-exposure antigen bind to IgE leading to degranulation and
- Lipid mediators causing smooth muscle contraction
- PAF and tryptase leading to superficial and systemic vasodilation
- Histamine leading to increase vascular permeabiltiy and
- utricaria which is fluid leak into superficial dermis
- angioedema with fluid leak into dermis and subcutaneous tissue
Discuss the treatment for anaphylaxis
- Vitals
- ABCDE
- if evidence of airway collapse then intubate early to prevent difficulties due to swelling
- Intramuscular epinephrine 0.3-0.5mg to mid-thigh
- can repeat q5 minutes for maximum 5 doses
- 0.01mg/kg IM
- Place in recumbent position
- feet elevated
- Oxygen 8-10L/min to keep O2 sat >92%
- Normal saline bolus with 1-2L IV for hypotension
- Salbutamol 2.5-5mg in 3mL saline nebulizer
- for bronchospasm resistant to IM epinephrine
Discuss the adjunctive therapies to anaphylaxis
- H1 antihistamine (Dimenhydramine 25-50mg IV over 5 min)
- for utricaria and itching
- H2 antihistamine (Famotidine 20mg IV over 20 min)
- Glucocorticoid (methylprednisone 125mg IV Q6H)
- Monitoring
Discuss the refractory therapies for anaphylaxis
Epinephrine infusion for inadequate response
- 0.1mcg/kg/min
Vasopressor if still unresponsive following epinephrine infusion
Glucagon for patients with beta-blocker
- 1-5mg IM to 5-15mcg/min IV
Discuss the secondary biphasic reaction for anaphylaxis
- is the recurrence of symptoms that develop following the initial exposure with re-exposure
- Symptoms can be milder, the same or worse than initial exposure
- can present 1-72hrs following with median being 10-12 hrs
- usually observe patient for 4-6hrs following last dose
Discuss the criteria for admission and discharge for those with anaphylaxis
Admission
- severe reaction (hypotension) or requiring >1IM epinephrine dose
- Continue to be symptomatic following 6-8hr observation
- Pre-existing asthma or beta-blocker
- Very old or very young
Discharge
- provide written action plan
- educate on allergen avoidance
- close follow up with GP
- Medications
- Epipen
- Dimenhydramine 25-50mg PO Q4-6H for 3 days
- Ranitidine 150 Q12H for 3 days
- Prednisone 50 mg PO OD for 3 days
Differentiate between heat exhaustion and heat stroke
Body Temperature
- 38.3 to 40C in exhaustion
- >40C for stroke
Thermoregulation
- body able to cool itself when removed from heat with rest in exhaustion
- body unable to cool itself and begins to overheat in stroke
CNS function
- No dysfunction in exhaustion
- seizure, altered LOC, and delirium in stroke
Discuss the diagnostic criteria and common symptoms of heat stroke
Criteria - Body temperature >40 - CNS dysfunction - Exposure to severe environmental heat Symptoms - muscle cramps - hypovolemic - syncope - headache - palpitation - oliguria
Discuss common investigations for heat stroke
- CBC may show leukocytosis
- renal function for acute renal failure with high BUN and creatinine
- liver function
- CK for rhabdomyolysis
- ECG
Discuss the management for heat stroke
Stabilize
- ABC
- consider central venous pressure to assess volume status (want between 8-12mmHg)
- require 250-500mL bolus of NS
Cooling
- continuous temperature monitoring through rectum or esophagus
- target core of 38-39
- lie patient naked and spray with lukewarm water while fan is blowing them
- Lorazapam 1-2mg IV to inhibit shivering and agitation
- Other cooling
- immersion is ice water
- water ice therapy
- ice packs to axilla, neck and groin
- peritoneal lavage
- cool blankets and cool IV fluids (22C)
- no need for anti-pyretics
Discuss the criteria of hypothermia and pathophysiology
Criteria
- Body temperature <35C with multisystemic features
- Mild 32-35
- Moderate 28-35
- Severe <28
Pathophysiology
- hypothalamus cause shivering and increase thyroid, adrenal, and sympathetic activity leading to peripheral vasoconstriction, hypertension, tachycardia, ileus and bladder atony
- cold damages cells and crystallizes water disrupting electrolyte concentrations
- vasoconstriction lead to blood stasis and increase risk for VTE
- cold also inhibits coagulation
- vasoconstriciton lead to tissue necrosis
- thawing cause marked edema due to melting water crystals and cellular damage
Discuss the systemic features associated with hypothermia
Thermoregulation
- mild have shivering intact
- moderate and severe has loss of shivering and rapid cooling
Hematologic
- Moderate increase hematocrit, thrombocytopenia, leukopenia and hypercoaguable
- severe have DIC and bleeding
Neurologic
- Mild have disorientation, ataxia, dysarthria and hyper-reflexia
- moderate have hallucinations, dilated pupils and hyporeflexia
- severe have coma, absent pupillary response
Respiratory
- Mild have tachypnea and bronchorrhea
- moderate have hypoventilation, respiratory acidosis, hypoxemia, atelectasis
- severe have apnea, pulmonary edema and respiratory distress
Cardiovascular
- Mild have tachycardia and hypertension
- Moderate have bradycardia, hypotension, and prolonged QTc and J waves
- Severe have heart block, atrial fibrillation, VF
GI
- Moderate and severe have pancreatitis, gastric ulcer and hepatic dysfunction
MSK
- hypertonia -> rigidity -> rhabdomyolysis
Discuss investigations for hypotheramia
Every 4hrs
- CBC
- electrolytes
- Blood glucose
- lactacte
- LFT
- lipase
- Creatinine and BUN
- CK
- PTT, INR, fibronogen
Discuss the technique for re-warming
Passive External Rewarming - for mild hypothermia warming at 0.5-2C per hour - blankets Active External Rewarming - for mild hypothermia without shivering or moderate - 2C per hour - heating blankets - heated force air systems - heated pads - radiant heat - warm baths (45C) Active Internal Rewarming - Simple - moderate hypothermia - 1-2C per hour - warmed IV fluids and warmed oxygen Active Internal Rewarming - Invasive - Moderate with cardiovascular compromise or severe - 1-4C per hour - Peritoneal irrigation - Pleural irrigation - Esophageal warming tubes - Endovascular rewarming Extra-Corporeal - Severe, renal failure/hyperkalemia, cardiac arrest - 2-3C per hour up to 9.5C per hour - AV or VV rewarming - Heated hemodialysis - Cardiopulmonary bypass
