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100 Cases in Surgery

ANSWER 95

Malnutrition leads to delayed wound healing, reduced ventilatory capacity, reduced immunity and an increased risk of infection. The nutritional status of a patient should be assessed daily.

The two main methods of feeding are either by the enteral route or the parenteral route.

Enteral feeding is via the gastrointestinal tract. It is less expensive and is associated with fewer complications than feeding by the parenteral route. Enteral feeding stimulates the bowel and encourages the production of mucosal factors, which maintain the normal physiological barrier to bacterial translocation. Patients who can take food orally can have their diet supplemented with nutritional drinks. If patients are not able to feed orally, then nasoenteral tube feeding should be considered. Nasogastric feeding is the mostly commonly used route. Tube tips can be placed in the duodenum or jejunum if there is pathology in the proximal part of the gastrointestinal tract. In the longer term, enteral feeding can be via a feeding gastrostomy or jejunostomy. These can be placed either endoscopically, radiologically or at the time of surgery. Disadvantages are that feeding tubes can become blocked or dislodged, leading to peritonitis.

The parenteral route should only be used if there is an inability to ingest, digest, absorb or propulse nutrients through the gastrointestinal tract. It can be administered by either a peripheral or central line. Peripheral parenteral nutrition can cause thrombophlebitis due to the hyperosmotic nature of the feed. Central parenteral nutrition needs to be delivered via a large central line – in the subclavian or jugular vein. Insertion of a central line carries a significant risk of complications, e.g. pneumothorax, haematoma, nerve injury and thrombosis. Sepsis is the most frequent and serious complication of centrally administered parenteral nutrition. The other serious complication relates to metabolic derangement, which occurs in up to 5 per cent of patients on parenteral nutrition.

A Hartmann’s procedure is a safe method of removing a diseased section of large bowel. After resection, the distal part of the bowel is closed and left in situ, and the proximal end is brought to the skin as an end colostomy. There is no anastamosis, which allows enteral nutrition to be started early.

KEY POINTS

•enteral feeding is preferred to parenteral feeding.

•a patient’s nutritional status should be assessed on a daily basis.

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Postoperative Complications

CASE 96: poStoperative pyreXia

history

As the doctor on call, you have been asked to assess an 86-year-old male patient on the ward who is 1 day post perforated peptic ulcer repair. The nurse is concerned as he has spiked a temperature. The operations note reports that there was minimal peritoneal soiling at the time of the operation. He has a morphine infusion, but his pain is poorly controlled. A urinary catheter remains from his operation and the urine output is adequate. Prior to his surgery he was fit, but he was a heavy smoker.

examination

His blood pressure is 130/90 mmHg, pulse rate 110/min, respiratory rate 30/min and temperature 38°C. His saturations have remained at 99 per cent on 24 per cent oxygen. On examination of his chest, you can hear coarse basal crepitations bilaterally and the lung bases are dull on percussion. Abdominal examination reveals tenderness around the incision site and the urinalysis is clear. Blood tests and a portable chest x-ray (Figure 96.1) are ordered and shown below.

INVESTIGATIONS

Figure 96.1 plain x-ray of the chest.

Questions

•What is the likely cause of the pyrexia in this patient?

•What are the risk factors?

•How should the patient be managed?

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100 Cases in Surgery

ANSWER 96

The chest x-ray shows a reduction in lung volume bilaterally, and basal consolidation. The patient has basal atelectasis as a consequence of pulmonary collapse. The patient’s inability to cough leads to the failure of clearance of bronchial secretions from the lungs. Consequently, there is occlusion and collapse of the lung segments. The collapsed lung is at risk of secondary infection by inhaled organisms, leading to a pneumonia.

Atelectasis is more common in patients with pre-existing lung disease, obese patients and heavy smokers. Patients who have undergone thoracic or upper-abdominal surgery find chest expansion limited by pain, making them more prone to basal lung collapse. The patient in this case has a number of risk factors for developing basal atelectasis. He is a heavy smoker and has an upper midline incision with poor postoperative pain control.

Patients with basal atelectasis usually develop a pyrexia at about 48 h, with an accompanying tachycardia and tachypnoea. Examination reveals bronchial breathing, and reduced air entry bibasally with dullness on percussion. The chest x-ray shows consolidation and collapse in the affected areas. The patient should be treated aggressively with chest physiotherapy to prevent pneumonia. Patient position, regular nebulizers and deep breathing help to clear secretions and to keep the lungs fully expanded.

With elective operations, these patients can be identified preoperatively. A thoracic epidural, regular nebulizers and chest physiotherapy may help to prevent basal lung collapse.

KEY POINTS

•patients at risk of respiratory complications should be identified preoperatively.

•good pain control and chest physiotherapy will help prevent basal atelectasis.

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Postoperative Complications

CASE 97: loW urine output

history

As the doctor on call, you are asked to review a postoperative patient on the ward. The patient is an 86-year-old man who had a right hemicolectomy for a caecal carcinoma 2 days previously. Preoperatively, he was on antihypertensive medication, which has not been restarted. During the day, his urine output had been poor, with a total of 75 mL produced over the past 8 h. He has taken very little fluid orally during the day. His epidural was removed earlier that afternoon and he has been started on non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief.

examination

He is alert and orientated in time, place and person. He is afebrile, blood pressure is 110/70 mmHg and pulse 110/min. His chest is clear and heart sounds are normal. His abdomen is tender around the incision, but otherwise soft and non-tender. He has normal bowel sounds and has opened his bowels since the operation.

INVESTIGATIONS

he had postoperative blood tests on day 1 which were normal. no blood tests were available from that day.

Questions

•What is normal minimal urine output expected in a 70-kg man?

•What are the causes of acute renal failure?

•What would be your approach to managing this patient?

•What biochemical changes would you see with acute renal failure?

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100 Cases in Surgery

ANSWER 97

Urine production should be greater than 0.5 mL/kg/h. The aetiology of acute renal failure can be thought of in three main categories:

•Pre-renal: the glomerular filtration is reduced because of poor renal perfusion. This is usually caused by hypovolaemia as a result of acute blood loss, fluid depletion or hypotension. The patient’s tubular and glomerular function are normal, so renal function should be restored with appropriate fluid replacement.

•Renal: this is the result of damage directly to the glomerulus or tubule. The use of drugs such as NSAIDs, contrast agents or aminoglycosides all have direct nephrotoxic effects. Acute tubular necrosis can occur as a result of prolonged hypoperfusion, either perioperatively or postoperatively. Pre-existing renal disease such as diabetic nephropathy or glomerulonephritis makes patients more susceptible to further renal injury.

•Post-renal: this can be simply the result of a blocked catheter. This should always be checked as a cause for complete anuria in a previously fit patient. Calculi, blood clots, ureteric ligation and prostatic hypertrophy can also all lead to obstruction of urinary flow.

This patient is likely to be dehydrated as a result of his poor oral intake since his operation. Firstly, check the catheter by flushing it and palpate the abdomen for a distended bladder. Then calculate his fluid balance since the operation. Check for any evidence of sepsis. With his current blood pressure, his antihypertensive medication does not need to be restarted. It is important to maintain a good blood pressure to ensure adequate renal perfusion. The NSAIDs should be stopped as these have a direct nephrotoxic effect which may worsen his renal function.

Examine the patient for any evidence of fluid overload and check his history for previous renal problems or cardiovascular disease. Initially, the patient should be given a fluid challenge. A bolus infusion of 250 mL should give an improvement in urine output if the cause is pre-renal. If after two attempts no improvement is seen, the patient should be considered for transfer to a high-dependency unit and central venous pressure monitoring.

!Biochemical changes in acute renal failure

•hyponatraemia

•hyperkalaemia

•hypocalcaemia

•metabolic acidosis

KEY POINT

• urine production should be greater than 0.5 ml/kg/h.

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