Anaesthesia for a minor procedure in a patient with fontan physiology
A 12 year-old girl weighing 41kg was posted for Botox (botulinum) injections and casting for spasticity of the right upper limb. She gave history of having some heart disease since birth for which multiple operations had been done. On going through her past medical records, it was found that she was born with complex congenital heart disease, having dextro-transposition of great arteries,double outlet right ventricle,pulmonary stenosis, and a large ventricular septal defect. She underwent a right subclavian to right pulmonary artery shunt shortly after birth, a Glenn operation at 4 months of age, and an extracardiac Fontan operation (total cavopulmonary conduit) at 5 years of age. She was on chronic therapy with warfarin. At age 10, she was hospitalized with a cerebrovascular accident for a month. Computed tomography (CT) brain showed left middle cerebral artery (MCA) thrombosis due to which she had developed right hemiparesis. The hemiparesis improved gradually and she developed spasticity of the right upper and lower limbs. She had developed pedal edema a few months earlier, due to an element of protein losing enteropathy, which was treated with diuretics and high protein diet. She gave history of no cardiovascular (CVS) complaints at the time of admission, and was regular in her studies and daily activities. She was on treatment with tablet warfarin 5mg and tablet furosemide 20mg once a day.\nOn examination, she was conscious, oriented, well nourished. She was afebrile, pulse was 82 beats/minute and regular, blood pressure was 102/66mm Hg. A median sternotomy scar was present. CVS examination showed a regular heart rate, and a grade 2 systolic murmur. She had spasticity of the right upper limb more than the lower limb. Rest of the systemic examination was unremarkable. Investigations revealed haemoglobin of 11.2g/dL, total and differential white blood cell counts were normal. Renal function tests, serum electrolytes, liver function tests including serum proteins were within normal limits. Prothrombin time was 22s, with an INR of 2.1. Electrocardiogram (ECG) showed sinus rhythm. Echo showed patent functioning cavopulmonary shunts, mild ventricular systolic dysfunction, no thrombi/vegetations.\nA cardiology opinion was taken. She was advised to withhold warfarin and switch over to a low-molecular weight (LMW) heparin 5 days prior to surgery. She was started on enoxaparin 40 mg subcutaneous twice a day. Infective endocarditis prophylaxis was also advised. Enoxaparin was withheld 12 hours prior to surgery.\nOn the night prior to surgery, patient was given tablet alprazolam 0.25mg. Infective endocarditis prophylaxis was given with IV ceftriaxone 1g 1 hour prior to the procedure. It was decided to give general anaesthesia since the patient was very apprehensive and insisted on it. Patient was taken to the operation theatre, monitors were attached (ECG, pulse oximeter, capnograph, non-invasive blood pressure monitor). An infusion of lactated Ringer's solution was started and she was preloaded with around 200ml. Patient was premedicated with IV ondansetron 4mg. Preoxygenation was done for 5 minutes and anaesthesia was induced with IV fentanyl 80 mcg and propofol 80mg IV slowly and maintained with sevoflurane 0.6-0.8% in 50% nitrous oxide in oxygen, on spontaneous ventilation with intermittent assist. Blood pressure was maintained within 20% of the baseline value. Fluids were given to maintain blood pressure. End-tidal CO2 was maintained between 30 and 35mm Hg. Patient received 300ml Ringer's lactate intraoperatively, and the procedure lasted 30minutes. At the end of surgery, a 50mg diclofenac per rectal suppository was given for post op analgesia. Once awake, responding to oral commands and stable, patient was shifted to the recovery room for monitoring. Patient was comfortable, and her vitals were stable. She was shifted to the ward after an hour and had an uneventful post operative period. She was discharged the next day.