Download Update 11 - Update in Anaesthesia - WFSA

Update in Anaesthesia 69(hypokalaemia) and sodium (hyponatraemia) ions. Theblood thickens and this may cause clotting problems suchas thrombosis, and could precipitate a crisis in a patientwith sickle cell disease.Assess the patient, rehydrate them and delay surgery ifnecessary. Remember the aim is a sugar level of 6-10mmol/l. If the sugar is below 10 mmol/l, observe andrecheck it hourly throughout the operation. Should it beabove 10 mmol/l, then follow the regimes in figures 1 - 4,according to the extent of the surgery planned.After surgery, the insulin requirements fall as the stressresponse subsides. Newly diagnosed diabetics need furtherinvestigation to establish whether they will need insulintherapy, oral hypoglycaemics or indeed just diet control.Sometimes when the blood sugar has become very high,the patient becomes comatose (diabetic coma). It is vitalto correct this by adhering to the general guidelines andregimes already mentioned. Aim to reduce the sugar levelsto below 10 mmol/l. When this has happened over a fewdays, the body uses its own fat to produce energy, andthis results in high levels of waste products (ketones) inthe blood and urine - this is called diabetic ketoacidiosisand is a medical emergency with a significant mortality.Diabetic ketoacidosisThis may be triggered by infections or other illnesses suchas bowel perforations and myocardial infarction. Thepatient will be drowsy or even unconscious with fast, deepbreathing due to acid in the blood. The ketones make theirbreath smell sweetly, like acetone. Ketones can also bedetected by the use of urine and blood testing strips.Diarrhoea, vomiting, gastric dilatation (insert a nasogastrictube) or even severe abdominal pain may be present whichcan be misinterpreted as an acute surgical problem! Assevere dehydration is usually present, surgery must bedelayed until fluid resuscitation has commenced in orderto avoid disastrous hypotension with induction agents. Aurinary catheter will help monitor fluid balance, and anECG and CVP line (to estimate the fluid deficit) are helpful.The aim is to slowly return the body chemistry to normal.Give high flow oxygen therapy.Although the blood potassium level is usually high, the bodyhas actually lost large amounts in the urine, and extrapotassium is required intravenously. It is important to lowerthe blood sugar level slowly, as reducing it too fast canresult in further complications such as brain oedema andconvulsions. Search for infections (chest X-ray, blood andurine cultures) and treat with antibiotics. Blood gases andelectrolyte measurements may also help management. figure5 gives a regime for treatment.Anaesthetic technique.Intraoperative monitoring - record blood pressure andpulse every 5 minutes during the operation, and watchskin colour and temperature. If the patient is cold andsweaty, then suspect hypoglycaemia, check the bloodglucose and treat with intravenous glucoseGeneral anaesthesia - if gastric stasis is suspected thena rapid sequence induction should be used. A nasogastrictube can be used to empty the stomach and allow a saferawakening. There are no contraindications to standardanaesthetic induction or inhalational agents, but if the patientis dehydrated then hypotension will occur and should betreated promptly with intravenous fluids. Hartmannssolution (Ringers lactate) should not be used in diabeticpatients as the lactate it contains may be converted toglucose by the liver and cause hyperglycaemia.Sudden bradycardias should respond to atropine 0.3mgiv, repeated as necessary (maximum 2 mg). Tachycardias,if not due to light anaesthesia or pain, may respond togentle massage on one side of the neck over the carotidartery. If not then consider a beta-blocker (propanolol1mg increments: max 10mg total or labetalol 5mgincrements: max 200mg in total).IV induction agents normally cause hypotension oninjection due to vasodilatation. If a patient has a damagedautonomic nervous system (and many diabetics do), thenthey cannot compensate by vasoconstricting, and thehypotension is worsened. Reducing the dose of drug andgiving it slowly helps to minimise this effect.Regional techniques - are useful because they get overthe problem of regurgitation, possible aspiration and ofcourse difficult intubation. However, the same attentionshould be paid to avoiding hypotension by ensuringadequate hydration. It is a wise precaution to chart anypre-existing nerve damage before your block is inserted.With spinals and epidurals, autonomic nerve damagemeans the patient may not be able to keep their bloodpressure in a normal range. Intervene early with ephedrine(6mg boluses) when the systolic pressure falls to 25%below normal.Postoperative therapy regimes are also given in figures 1 -4. It is not unusual to find that insulin requirements arereduced once the patient begins to recover from surgery.