Diagnosis & Treatment — General practitioner / health post
General problems
Patient history with regard to pre-existing conditions and medications:
1. known Hymenoptera allergy?
2. coronary heart disease?
3. beta-blocker use?
How severe is the allergic reaction?
Inquire re:
- When did the sting(s) occur?
Assess:
- state of consciousness.
Measure:
- blood pressure/pulse,
- breathing (respiratory rate).
Classification of allergic reactions (Müller 1988):
1. Local reaction:
- local swelling (diameter: >10 cm?; duration: >24 h?).
2. Systemic reactions:
- Grade I: generalised urticaria, pruritus, nausea, fear.
- Grade II: grade I symptoms plus 2 or more of the following: angio-oedema (if this symptom appears in isolation, this is already a grade II reaction), a feeling of tightness in the throat or chest, vomiting, diarrhoea, abdominal cramps, dizziness.
- Grade III: grade I and II symptoms plus 2 or more of the following: respiratory distress, rhonchi, stridor (if any of one of these symptoms appears in isolation, this is already a grade III reaction), dysphagia, dysarthria, hoarseness, weakness, drowsiness, fear of death.
- Grade IV: grade I–III symptoms plus 2 or more of the following: fall in blood pressure, collapse, loss of consciousness, incontinence (urine, faeces), cyanosis.
- Uncommon reactions: see Therapy phase: Hospital.
See below.
In a cohort study of patients with a known Hymenoptera allergy, patients were subjected to an insect sting challenge and then symptoms of anaphylaxis were observed and the plasma levels of catecholamines and angiotensin were measured before and after the sting challenge. A recurrent allergic reaction occurred in 28% of the subjects. A severe reaction (grade IV) was only observed in those subjects who had already demonstrated a severe reaction (grade IV) in response to previous stings (17/73) (van der Linden et al. 1993).
Has the patient been stung in the oral cavity?
Assessment: laryngeal oedema.
H1-antihistamine i.v. (e.g. clemastine 2 mg)
and
corticosteroids i.v. (e.g. prednisolone 100 mg or methylprednisolone 80 mg).
If laryngeal oedema occurs: adrenaline 10–20 inhalations (children: 2–4 inhalations/10 kg body weight) (Medihaler) or adrenaline 0.3–0.5 mg s.c. (children: 0.1 mg/10 kg body weight). If the laryngeal oedema persists, adrenaline can be administered every 20–30 min.
Plus
ready to perform endotracheal intubation/tracheotomy.
(Müller et al. 1991).
Are there multiple stings with the risk of a toxic course of envenoming?
Inquire re:
- When did the stings occur?
Assess:
- state of consciousness.
Measure:
- blood pressure/pulse,
- breathing (respiratory rate).
Count: the number of stings (simultaneously removing any stings remaining in the skin according to first aid methods: see Therapy phase: First aid / lay people).
Classification with multiple stings: when toxic symptoms are present, it is likely that >50 stings have occurred.
Maintain vital organ functions.
H1-Antihistamine i.v. (e.g. clemastine 2 mg) and corticosteroids i.v. (e.g. prednisolone 100 mg or methylprednisolone 80 mg).
For the treatment of severe allergic reactions, see below.
Hospitalisation; see also Apoidea: Clinic: Recommendations (Franca et al. 1994).
The cytotoxic action of melittin, phospholipases and kinins of wasp and hornet venom can cause tissue damage to the skin, musculature (rhabdomyolysis) and liver as well as haemolysis (Müller 1988).
Toxic venom effects have been observed primarily following multiple stings from wasps and hornets. This type of complication occurs only rarely following bee stings and only after hundreds to thousands of stings (see Bousquet et al. 1984).
Emergency medical treatment of allergic reactions
1. Cutaneous signs and symptoms
- Extensive local skin reaction
Cooling, immobilisation and elevation of the affected extremity;
or, if necessary,
oral H1-antihistamine (e.g. terfenadine 120 mg twice daily, clemastine 1 mg twice daily, cetirizine 10 mg/day, loratadine 10 mg/day) and oral corticosteroids until the signs and symptoms have disappeared (Müller et al. 1991).
Antihistamines can be effective if they are administered sufficiently early.
- Delayed skin symptoms
Topical steroids
or, if necessary,
oral corticosteroids (e.g. prednisone 50–100 mg/day) until the signs and symptoms have disappeared (Müller et al. 1991).
- Urticaria,
- angio-oedema,
- generalised oedema
H1-Antihistamine i.v. (e.g. clemastine 2 mg)
or, if necessary,
adrenaline 0.3–0.5 mg s.c. (children: 0.1 mg/10 kg body weight)
and
corticosteroids i.v. (e.g. prednisolone 100 mg or methylprednisolone 80 mg).
Monitoring until the signs and symptoms have improved, for at least 1 hour (Müller et al. 1991).
2. Respiratory symptoms
- Bronchial obstruction
Adrenaline 10–20 inhalations (children: 2–4 inhalations/10 kg body weight) (Medihaler) or 0.3–0.5 mg (children: 0.1 mg/10 kg body weight) s.c.
plus
corticosteroids (e.g. prednisolone 100 mg; children 20 mg/10 kg body weight) i.v.
Persistence of symptoms: repeat administration of adrenaline every 10–20 min.
Alternative treatments for bronchial obstruction:
- β2-stimulator 4–10 inhalations (e.g. salbutamol, terbutaline) or salbutamol 5–10 µg/min i.v. (severe symptoms),
- plus possibly aminophylline 6 mg/kg body weight within 20 min, then 0.9 mg/kg body weight per hour,
- plus corticosteroids (e.g. prednisolone 100 mg) i.v.
Additional measures:
- oxygen,
- observation until symptom free,
- endotracheal intubation or tracheotomy (Müller et al. 1991).
- Laryngeal oedema
Adrenaline 10–20 inhalations (children: 2–4 inhalations/10 kg body weight) (Medihaler) or 0.3–0.5 mg (children: 0.1 mg/10 kg body weight) s.c.
Persistence of symptoms: repeat administration of adrenaline every 10–20 min.
Additional measures:
- oxygen,
- observation until symptom free,
- endotracheal intubation or tracheotomy (Müller et al. 1991).
3. Anaphylactic shock
- Place the patient in the shock position;
- oxygen;
- intravenous access and physiological salt solution (or plasma expander);
- adrenaline 0.3–0.5 mg (children 0.1 mg/kg body weight) i.m. (s.c.), in severe cases i.v. 0.5 mg (children 0.1 mg/10 kg body weight) in 10 ml NaCl within 5 min; repeat every 10–20 min if necessary;
- H1- or H2-antihistamine i.v., e.g. clemastine 2 mg (children 1–2 mg), ranitidine 100 mg (children 15 mg/10 kg body weight);
- corticosteroids i.v., e.g. prednisolone 100 mg (children 20 mg/10 kg body weight);
- endotracheal intubation;
- hospitalisation (Müller et al. 1991).
Particularly severe and prolonged anaphylaxis is observed in patients who take beta-blockers. Thus it is often necessary to administer higher and repeated doses of adrenaline or other beta-adrenergics. The use of H2-antihistamines is problematic, as these can cause bradycardia, and, in addition, cimetidine inhibits the clearance of beta-blockers (Toogood 1988).
Exclusion of a clinically relevant allergic reaction
Monitoring for signs and symptoms of an allergy for at least 24 h.
Local treatment
Sting, including the surrounding reaction
- Assessment of the wound according to the usual criteria.
- Swelling: assessment of the extent and increase in magnitude.
- Long-term: observation for the formation of necrosis.
- Cleaning, disinfection and dressing of the wound at regular intervals. Immobilisation of the extremity with a splint.
- Padding and monitoring to prevent pressure necrosis and disturbance of the blood circulation if the oedema increases.
- Possibly also prophylactic antibiotic treatment.
Tetanus
Tetanus prophylaxis.