Medicines to Treat Complications of Anaesthesia
Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level, Adults 2019 Edition
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Anaesthetic-related Acute Hypotension
Anaesthesia-related Acute Hypertension
Postoperative Nausea and Vomiting (PONV)
MALIGNANT HYPERTHERMIA
ICD-10 Code: T88.3
- Dantrolene IV, 2 mg/kg as a single dose (preferably through large bore cannula).
- Reconstitute with 60 mL water for injection. For a 70 kg patient, 175 mg (9 vials) is required.
- Administer subsequent doses to clinical effect (cardiac and respiratory symptoms stabilise, muscle tone and body temperature reduced).
- Doses higher than 10 mg/kg is uncommon and the clinician should question the diagnosis.
- Although, high doses of 10 mg/kg may be required in muscular males.
LOCAL ANAESTHETIC TOXICITY
ICD-10 Code: T41.3
Airway management:
- Ventilate with 100% oxygen.
Seizure suppression:
- Diazepam, IV, 10 mg.
Cardiopulmonary resuscitation may be required.
- Reduce individual adrenaline (epinephrine) doses to < 1 mcg/kg.
- Lipid emulsion (20%), IV, 1.5 mL/kg over 1 min, then continuous infusion 0.25 mL/kg/min.
- Repeat bolus 1–2 times for persistent cardiovascular collapse.
- Double infusion rate to 0.5 mL/kg/minute if BP remains low.
- Continue infusion for at least 10 minutes after cardiovascular stability attained.
- Recommended upper limit: approximately 10 mL/kg lipid emulsion over the first 30 minutes.
ANAESTHETIC-RELATED ACUTE HYPOTENSION
ICD-10 Code: I95.81
Treat the cause of hypotension.
Ensure appropriate fluids are given to correct hypovolaemia.
The medicines given below all require significant dilution before administration.
- Adrenergic and dopaminergic agents, e.g.:
- Ephedrine IV, 3–5 mg as a single dose and then further boluses as required to a maximum of 30 mg.
- Increases heart rate and contractility, and vasoconstrictor.
- Repeated administration can result in tolerance and tachyphylaxis.
- Alternative vasopressor infusion (e.g. adrenalin (epinephrine)) may be needed to mitigate unresponsiveness to treatment
- Ephedrine IV, 3–5 mg as a single dose and then further boluses as required to a maximum of 30 mg.
OR
- Phenylephrine IV, 50–100 mcg as a single dose and then infuse at 60–180 mcg/minute.
- Vasoconstrictor.
- High doses may cause significant reflex bradycardia: treat this by discontinuing the phenylephrine only.
ANAESTHESIA-RELATED ACUTE HYPERTENSION
ICD-10 Code: I97.3
To obtund the hypertensive response to intubation i.e. pre-eclampsia:
- Alfentanil, IV, 7.5 mcg/kg (with magnesium sulfate, IV 30 mg/kg)
During anaesthesia or post-operatively, establish the cause (e.g. light anaesthesia or inadequate pain relief) and treat as appropriate.
- Labetalol IV, 5–10mg IV over 2 minutes.
- Repeated at intervals of at least 5 minutes to maximum 200 mg.
- Duration of action 50 minutes.
- Vasodilates and slows heart rate.
POSTOPERATIVE NAUSEA AND VOMITING (PONV)
Prevention of PONV
ICD-10 Code: R11.2
- Patients identified preoperatively as medium or high risk for PONV should be considered for prophylactic antiemetics.
- Prophylactic antiemetics also required if postoperative vomiting is potentially dangerous, e.g. after jaws wired, open eye surgery, oesophageal surgery.
- High risk patients should receive anti-emetics from ≥ 1 class.
- Adequate IV hydration associated with less PONV.
| Risk factors for PONV |
Points |
| Female Gender |
1 |
| Non-Smoker |
1 |
| History of PONV and/or motion sickness |
1 |
| Postoperative opioids |
1 |
| Sum |
0-4 |
| Points |
Risk for PONV (%) |
Risk category |
| 0 |
10 |
Low |
| 1 |
20 |
Low |
| 2 |
40 |
Medium |
| 3 |
60 |
High |
| 4 |
80 |
High |
| Class |
Anti-emetic |
Prophylactic Dose and timing |
Notes |
| Corticosteroid (glucocorticoids) | e.g.: Dexamethasone | 4-8 mg, IV, on induction. LoE:II32 |
Increases blood glucose in diabetics. Only used for prophylaxis, not established PONV. |
| 5-HT3 receptor antagonist |
e.g.: Odansetron | 4-8 mg, slow IV/IM, on induction. LoE:III33 |
Prolongs QTc interval |
| Phenothiazine |
Promethazine | 6.25–12.5 mg, IV (large bore cannula) diluted to 20 mL over 10-20 minutes, or deep IM, at end of surgery. |
Intra-arterial injection causes gangrene. Extravasation or subcutaneous injection associated with skin necrosis. Anticholinergic side effects and sedation. |
Treatment of PONV
ICD-10 Code: R11.2
Ensure adequate hydration and correct hypotension if present.
Give an emetic from a different class than the prophylactic agent given (except dexamethasone, which is only used for prophylaxis).
- Metoclopramide, IM/IV
- If < 60kg: 5mg IM or IV (over 2 minutes).
- If ≥ 60kg: 10mg IM or IV (over 2 minutes).
- Repeat 8 hourly if required.
Note
Metoclopramide can cause extrapyramidal side effects.
Treat acute dystonic reactions with:
- Anticholinergic agent, e.g.:
- Biperiden, IM/IV, 2 mg.
- Repeat as necessary.
- Biperiden, IM/IV, 2 mg.
If an anticholinergic agent is not available:
- Promethazine, deep IM, 25–50 mg.
- In the elderly 25 mg.
If an anticholinergic agent or promethazine is not available:
- Diazepam, IV, 5-10 mg for symptom relief.
ACID ASPIRATION PROPHYLAXIS
ICD-10 Code: O74.0
The use of a non-particulate, non-effervescent antacid reduces the risk of pneumonitis if gastric fluid is aspirated. Give to patients at risk of aspiration, e.g. pregnant women before Caesarean delivery.
- Sodium citrate, 0.3M, oral, 30 mL.
- Not more than 30 minutes pre-induction of anaesthesia.
Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level, Adults 2024 Edition