Anaphylaxis in infants and children: diagnosis, treatment

2021-06-18 04:41 PM

Danger signs such as shortness of breath, wheezing, increased breathing rate, constriction, persistent cough, cyanosis, signs of poor perfusion, abdominal pain, vomiting, arrhythmia, hypotension, depressed.

Anaphylaxis in infants and children, diagnosis, treatment

Clinical diagnosis

The most common signs and symptoms are cutaneous (eg, sudden generalized urticaria, angioedema, flushing, pruritus). However, 10 to 20 percent of patients have no skin findings.

Danger signs: rapidly progressive symptoms, signs of respiratory distress (eg, shortness of breath, wheezing, dyspnoea, increased respiratory rate, constriction, persistent cough, cyanosis), signs of poor perfusion, abdominal pain, vomiting, arrhythmia, hypotension, collapse.

Acute treatment

The first and foremost therapy in anaphylaxis is epinephrine. There are no absolute contraindications to epinephrine in the treatment of anaphylaxis.

Airway: Intubate immediately if there is evidence of impending airway obstruction due to angioedema. Delays can lead to complete blockages. Intubation can be difficult and should be performed by the most experienced clinician. Tracheostomy may be necessary.

Epinephrine IM (1 mg/mL preparation): epinephrine 0.01 mg/kg should be injected in the mid-lateral thigh region. For older children (> 50 kg), the maximum is 0.5 mg per dose. If there is no response or an inadequate response, a booster injection may be given after 5 to 15 minutes (or more often). If epinephrine is given intramuscularly immediately, the patient will respond to one, two, or at most three injections. If there are signs of poor perfusion or symptoms that do not respond to epinephrine injection, prepare intravenous epinephrine for infusion.

Place the patient in a supine position, if acceptable, and elevate the lower extremities.

Oxygen: Deliver 8 to 10 L/min via the surface or up to 100% oxygen, if necessary.

Rapid infusion of normal saline: Administer fluid therapy with a rapid infusion of 20 mL/kg. Reassess and repeat the infusion (20 mL/kg), if necessary. Massive fluid changes with severe intravascular volume loss may occur. Monitor urine output.

Albuterol: For bronchospasm resistant to intravenous epinephrine, give albuterol 0.15 mg/kg (minimum dose: 2.5 mg) in 3 mL saline inhaled through a nebulizer. Repeat if necessary.

H1 antihistamines: Consider giving diphenhydramine 1 mg/kg (maximum 40 mg IV, over 5 minutes) or cetirizine (children 6 months to 5 years can receive 2.5 mg IV, those 6 to 11 years old can inject 5 or 10 mg intravenously, over 2 minutes).

H2 antihistamines: Consider giving famotidine 0.25 mg/kg (maximum 20 mg) intravenously, for at least 2 minutes.

Glucocorticoids: Consider giving methylprednisolone 1 mg/kg (maximum 125 mg) intravenously.

Monitoring: Continuous non-invasive hemodynamic monitoring and pulse oximetry monitoring is required. Urine output should be monitored in patients receiving IV fluid resuscitation for hypotension or severe shock.

Treatment of drug-resistant symptoms

Epinephrine infusion(*): In patients who have failed to respond adequately to intramuscular epinephrine and intravenous saline, continuous epinephrine infusion at 0.1-1 mcg/kg/min, titrated for effect.

Vasopressors(*): Patients may require large amounts of intravenous fluid to maintain blood pressure. Some patients may require a second vasopressor (in addition to epinephrine). All vasopressors should be infused with an infusion pump, with dosages continuously titrated against blood pressure and heart rate/cardiac function continuously monitored and oxygen monitored with a pulse oximeter.

(*): All patients receiving epinephrine and/or another vasopressor require continuous non-invasive monitoring of blood pressure, heart rate, and function, and oxygen saturation. The guide prepares standard concentrations and provides charts of established infusion rates for epinephrine and other vasopressors in infants and children.

Note: A child is defined as a prepubertal patient weighing less than 40 kg.

Related articles: 

- Pediatric Allergy - Principles and Practice - Expert Consult (Pdf)

- A life-threatening allergic reaction (anaphylaxis)

- Anaphylaxis in Infants & Children

- What is Anaphylaxis?