Emergency Strategy - How to treat anaphylaxis
Emergency strategy - How to treat anaphylaxis
What is anaphylaxis? Anaphylaxis is an IgE mediated immune allergic hypersensitivity response to a foreign element that patient has been sensitized previously. It is a type 1 hypersensitivity reaction . Anaphylaxis is different from anaphylactoid reaction in which anaphylactoid reaction is reaction where the mechanism has not been identified or non immunological in nature.
Risk factors for developing anaphylaxis are exposure to causative agent, previous history of anaphylaxis and any atopy history. The causes of anaphylaxis are insect stings, food, food additives, contrast media, plasma substitutes, blood products, drugs and vaccine.
Generally the symptoms will develop on 5- 10 minutes after exposure to causative agent. Several hours delayed onset, late phase reaction / biphasic reaction ( symptoms recurrence for 48 hours despite therapy ), protracted anaphylaxis are common variance of anaphylaxis. Anaphylaxis symptoms may include pruritus, angioedema,urticaria, burning rash, wheeze, pulmonary edema, acute respiratory distress syndrome, laryngeal edema, shock, hypovolemia, arrhythmias, abdominal cramps and nausea.
The management initially involves opening the airway, maintaining the breathing/ ventilation system and improving the circulation system. Patient is placed in a recumbent position . The lower extremities are elevated. Every two to five minutes , oxygen saturation and vital signs are monitored. Remain with the patient at all times. Facemask is required for oxygen supply/ventilation. Consider endotracheal intubation if the facemask unable to ventilate the patient. Tracheostomy/ cricothyroidotomy is only consider in cases of laryngeal edema.
In hypovolemic patient, considered insertion of 2 large bore cannula. Give immediately adrenaline. In mild case, consider 0.3 - 0. 5mg ( 0.3- 0.5 ml of 1 in 1000 adrenaline) intramuscular and at 20 minutes interval repeats the procedure twice up to 3 doses given . 3- 5 ml of 1 : 10000 IV or via ETT ( endotracheal tube) is given in cases of major airway compromise or hypotension. The dose is repeated every 5- 10 minutes. Adrenaline infusion is considered in case which require multiple doses of IV adrenaline. 5 mg of adrenaline are diluted in 500 ml of normal saline or D5% ( 10 microgram/ml). 1 microgram per minutes is the initial dose which later titrated to up to 0.2 microgram/kg/min.
It is important to maintain an acceptable urine output and blood pressure by considering 500 - 1000 ml of crystalloid or colloid solution ( volume expansion). Inotropes are only considered in cases of persistent hypotension despite fluid replacement and pharmacological agents. The common inotropic agents adrenaline, isoprenaline and dopamine. Inotropes are considered due to hypotension which is unresponsive to the IV fluid and bolus adrenaline injection. Bronchodilator such as nebulized beta agonist is given in patient with bronchospasm. 2.5 - 5 mg of salbutamol every 15 - 30 minutes are considered. Refractory bronchospasm is treated with adding aminophylline as an additional bronchodilator.
Glucocorticoid is given with the aim to reduce protracted anaphylaxis or risk of recurrence. In mild cases, 20 mg of prednisolone is given orally . 250 mg IV hydrocortisone or 5mg/kg hydrocortisone are also given.The doses are repeated every 6 hours. Antihistamines are given to the patient and continue until anaphylaxis reaction resolves completely. 2 forms of antihistamines , such as 25 - 50 mg diphenhydramine IV or 10 mg chlorpheniramine IV are given to the patient. H1 and H2 blockers ( diphenhydramine), are prefer than H1 blocker . DIphenhydramine is used in conjunction with cimetidine and ranitidine. If the patient is unresponsive to adrenaline, 1 mg glucagon bolus or intravenously are considered. 1-5 mg/hr of continuous glucagon infusion is considered if required.
Any mild or moderate anaphylaxis reaction that presented as mild bronchospasm and urticaria are observed for 6 hours minimum. Patient should be admitted to the hospital in cases of moderate to severe reaction as the anaphylaxis reaction may relapse. Close monitoring of the blood pressure , central venous pressure adn arterial blood gases as well as continuous ECG are considered and the patient is managed in intensive care unit ( severe anaphylaxis cases). Relapses are prevented by antihistamines regimen 48 -72 hours with or without H2 antagonist. Hypotension and bronchospasm are treated with 7 - 10 days of short courses of steroid. Patient is advised to carry / wear key chain, necklace or medical alert bracelet to warn and inform health related worker in emergency setting regarding the risk of anaphylaxis.
What is anaphylaxis? Anaphylaxis is an IgE mediated immune allergic hypersensitivity response to a foreign element that patient has been sensitized previously. It is a type 1 hypersensitivity reaction . Anaphylaxis is different from anaphylactoid reaction in which anaphylactoid reaction is reaction where the mechanism has not been identified or non immunological in nature.
Risk factors for developing anaphylaxis are exposure to causative agent, previous history of anaphylaxis and any atopy history. The causes of anaphylaxis are insect stings, food, food additives, contrast media, plasma substitutes, blood products, drugs and vaccine.
Generally the symptoms will develop on 5- 10 minutes after exposure to causative agent. Several hours delayed onset, late phase reaction / biphasic reaction ( symptoms recurrence for 48 hours despite therapy ), protracted anaphylaxis are common variance of anaphylaxis. Anaphylaxis symptoms may include pruritus, angioedema,urticaria, burning rash, wheeze, pulmonary edema, acute respiratory distress syndrome, laryngeal edema, shock, hypovolemia, arrhythmias, abdominal cramps and nausea.
The management initially involves opening the airway, maintaining the breathing/ ventilation system and improving the circulation system. Patient is placed in a recumbent position . The lower extremities are elevated. Every two to five minutes , oxygen saturation and vital signs are monitored. Remain with the patient at all times. Facemask is required for oxygen supply/ventilation. Consider endotracheal intubation if the facemask unable to ventilate the patient. Tracheostomy/ cricothyroidotomy is only consider in cases of laryngeal edema.
In hypovolemic patient, considered insertion of 2 large bore cannula. Give immediately adrenaline. In mild case, consider 0.3 - 0. 5mg ( 0.3- 0.5 ml of 1 in 1000 adrenaline) intramuscular and at 20 minutes interval repeats the procedure twice up to 3 doses given . 3- 5 ml of 1 : 10000 IV or via ETT ( endotracheal tube) is given in cases of major airway compromise or hypotension. The dose is repeated every 5- 10 minutes. Adrenaline infusion is considered in case which require multiple doses of IV adrenaline. 5 mg of adrenaline are diluted in 500 ml of normal saline or D5% ( 10 microgram/ml). 1 microgram per minutes is the initial dose which later titrated to up to 0.2 microgram/kg/min.
It is important to maintain an acceptable urine output and blood pressure by considering 500 - 1000 ml of crystalloid or colloid solution ( volume expansion). Inotropes are only considered in cases of persistent hypotension despite fluid replacement and pharmacological agents. The common inotropic agents adrenaline, isoprenaline and dopamine. Inotropes are considered due to hypotension which is unresponsive to the IV fluid and bolus adrenaline injection. Bronchodilator such as nebulized beta agonist is given in patient with bronchospasm. 2.5 - 5 mg of salbutamol every 15 - 30 minutes are considered. Refractory bronchospasm is treated with adding aminophylline as an additional bronchodilator.
Glucocorticoid is given with the aim to reduce protracted anaphylaxis or risk of recurrence. In mild cases, 20 mg of prednisolone is given orally . 250 mg IV hydrocortisone or 5mg/kg hydrocortisone are also given.The doses are repeated every 6 hours. Antihistamines are given to the patient and continue until anaphylaxis reaction resolves completely. 2 forms of antihistamines , such as 25 - 50 mg diphenhydramine IV or 10 mg chlorpheniramine IV are given to the patient. H1 and H2 blockers ( diphenhydramine), are prefer than H1 blocker . DIphenhydramine is used in conjunction with cimetidine and ranitidine. If the patient is unresponsive to adrenaline, 1 mg glucagon bolus or intravenously are considered. 1-5 mg/hr of continuous glucagon infusion is considered if required.
Any mild or moderate anaphylaxis reaction that presented as mild bronchospasm and urticaria are observed for 6 hours minimum. Patient should be admitted to the hospital in cases of moderate to severe reaction as the anaphylaxis reaction may relapse. Close monitoring of the blood pressure , central venous pressure adn arterial blood gases as well as continuous ECG are considered and the patient is managed in intensive care unit ( severe anaphylaxis cases). Relapses are prevented by antihistamines regimen 48 -72 hours with or without H2 antagonist. Hypotension and bronchospasm are treated with 7 - 10 days of short courses of steroid. Patient is advised to carry / wear key chain, necklace or medical alert bracelet to warn and inform health related worker in emergency setting regarding the risk of anaphylaxis.