Case Study Reports: Postoperative Confusion

POSTOPERATIVE CONFUSION

History

You are on call and are asked to see a woman in the day surgery unit who is confused postoperatively. She is 42 years old and underwent transcervical resection of multiple submucosal fibroids in the early afternoon after presenting with menorrhagia. Four fibroids were resected and the estimated blood loss was 150 mL.

Examination

The woman knows her name but is disorientated, scoring only 5/10 on a mini mental state examination. She seems slightly drowsy.

The heart rate is 100/min and the blood pressure is 105/70 mmHg. Oxygen saturation is 94 per cent on air. She is apyrexial. Chest examination reveals dullness at both bases with fine inspiratory crackles. The abdomen is not distended but there is generalized lower abdominal tenderness. No masses are palpable and there are no signs of peritonism. You can see that there is small amount of blood from the vagina, but the loss is not excessive. You are told that she passed urine an hour ago without difficulty.

The operation note is reviewed and you find that the procedure was essentially uncompli- cated but was halted before all the fibroids could be fully resected because of the fluid imbalance. The fluid deficit is recorded as 1010 mL. However you review the actual fluid chart and it is as follows:

Fluid input (glycine, via operating hysteroscope input channel): 1000 mL

1000 mL

1000 mL

950 mL

Fluid output (via operating hysteroscope output channel):

1940 mL

Questions

·             What is the diagnosis and why has it occurred?

·             How would you manage this patient?

Answer:

The chest examination and X-ray suggest pulmonary oedema. Investigations show hyponatraemia and this is a recognized cause of a confusional state. There is also hypokalaemia which puts her at risk of dysrhythmia or cardiac arrest.

There has been an error in calculating the fluid deficit such that the deficit is in fact 2010 mL rather than 1010 mL. The hyponatraemia is therefore caused by fluid overload, a recognized complication of transcervical resection procedures. The normal upper limit for the procedure is 1000 mL and in this case twice that volume has been absorbed.

Management

The mainstay of management is supportive with monitoring of electrolytes and fluid restriction. Potassium supplementation should be given and electrocardiogram (ECG) monitoring employed until the potassium is normal.

The woman should be transferred to a high-dependency bed and given oxygen. Arterial blood gas should be monitored, and if the pulmonary oedema worsens then diuretics will be needed.

The hyponatraemia usually corrects itself with time and fluid restriction, and the acute confusional state would be expected to resolve as the electrolytes normalize.

The fibroids were not completely resected and a repeat ultrasound or outpatient hysteroscopy may be considered after a few weeks to check whether further surgery is needed – sometimes degeneration may occur as a result of thermal damage or inflammation from the initial pro- cedure. Alternatively any fibroid remnants may be expelled spontaneously through the cervix and vagina.