Post-operative Opioid-Induced Hyperalgesia


An elderly female was admitted to the intensive care unit (ICU)following a planned hemi-hepatectomy to remove metastatic lesions from a previously resected primary colorectal cancer. The patient had declined neuraxial anaesthesia. The surgery proceeded uneventfully via a rooftop incision under general anaesthesia, which was maintained with remifentanil, sevofluorane and paralysis with atracurium.

30 minutes before the termination of the three hour operation, a bolus of 10mg of morphine was given intravenously and a patient-controlled analgesia (PCA) morphine pump was prepared. At emergence from anaesthesia, paralysis was reversed, and the patient was successfully extubated. In the ICU the patient was instructed in the use of the PCA. She was initially comfortable, but within 30 minutes she complained of worsening abdominal pain around the upper abdominal incision and became tachycardic.

To address this patient’s worsening post-operative abdominal pain 10mg of morphine was given intravenously. Simultaneously she was reassessed and the potential cause of the pain was sought. The abdomen remained soft and mildly tender. Drains were dry, and parameters including blood pressure, respiratory rate, haemoglobin, and arterial blood gases were satisfactory.

The morphine was ineffective. She was given 1g of intravenous paracetamol, a further bolus of 10mg of morphine and two sequential 500mL aliquots of crystalloid. Surgical review was requested. After another 20 minutes the pain had not diminished so she received a bolus of fentanyl and a trial dose of 100mg of intravenous tramadol. Unfortunately these measures did not reduce the pain at all. Although vital signs were unchanged, the patient was increasingly distressed.

There was no apparent clinical deterioration to account for the increased pain. Yet, control of her symptoms had clearly been lost and routine analgesia was ineffective. Urgent senior review was requested. Suspecting that she had become refractory to opioid analgesia, and concerned about the severity of the pain and its potential complications, the consultant stopped the patient’s PCA, increased the inspired oxygen fraction to 0.80 through a non-rebreathe mask, and gave 50mg of ketamine intravenously.

These interventions significantly improved symptoms over the next ten minutes. The patient remained conscious though slightly drowsy and her tachycardia settled. Simple analgesics and a low dose infusion of 2-5 mcg/kg/min (approximately 10-25 mg/h) of ketamine were prescribed. These effectively controlled her pain. After the patient had remained comfortable and clinically stable for several hours, the PCA was gradually re-introduced and the ketamine was discontinued. She was discharged to the ward the following day.

What is opioid-induced hyperalgesia?Read More »

Declining Admission to Intensive Care

An 86 year-old man was referred to ICU because of oliguria, acidaemia and decreased conscious level. He had originally been referred by the general practitioner to the acute general medicine team with unexplained weight loss, malaise and reduced mobility, 19 days previously. He had a longstanding history of bronchiectasis and COPD. He had been able to mobilise independently around his house and garden until suffering a pneumonia several months before this admission, and since required a four-times-daily care package.

During the current admission the patient had been treated for a further pneumonia on the basis of new chest x-ray changes, breathlessness and raised inflammatory markers. He had also undergone a CT chest/abdomen/pelvis for the unexplained weight loss. This was consistent with chronic COPD and bronchiectasis but no other positive findings. A week prior to ICU referral he was found to have acute kidney injury (creatinine 280 µmol/mL, baseline 90 µmol/mL) which had failed to improve. In the 24 hours prior to referral had become progressively drowsy and oliguric.

The patient appeared frail, cachectic and oedematous. He groaned in response to voice and could not follow commands. He had Kussmaul breathing at a rate of about 18 breaths per minute with SaO2 of 91% on 35% oxygen via facemask. Arterial blood gas showed pH 7.09, pCO2 7.1 kPa, pO2 9.1 kPa, base excess -9.3 mEq/L, lactate 1.3 mmol/L, glucose 8.7 mmol/L, creatinine 294 µmol/mL. His chest x-ray showed persistent bilateral patchy consolidation. He had a blood pressure of 98/55 mmHg with a pulse of 110 beats/min and cool peripheries. ECG showed sinus tachycardia. He was afebrile. Abdomen was soft and a urinary catheter had drained only 25 mL in the last 4 hours. Other than reduced responsiveness, neurological survey was non-diagnostic.

Evaluation of this patient revealed an elderly man who was severely unwell with acute kidney injury, probable sepsis, and a poor response to treatment to date. This was on the background of chronic suppurative lung disease, and diminished health for several weeks. No specific treatment limitations were in place. His next-of-kin was unaware of any prior expressed wishes and was under the impression that the patient would prefer active treatment. The referring team were of the opinion that intensive care should be considered.

Although no unifying diagnosis for this gentleman’s kidney injury had been identified, a single, rapidly-reversible condition was not apparent. The principal indication for intensive care was for renal replacement therapy for an unknown duration. In view of the status of his neurological, respiratory and cardiovascular systems, it was deemed that airway protection, invasive respiratory support and vasopressor treatment would almost certainly be required. His overall health status made the prospect of survival from a prolonged period of multi-organ support on intensive care highly unlikely. After discussion with the intensive care consultant and the referring consultant it was decided to withhold admission to the intensive care unit. Appropriate family discussions were held. The patient was actively managed on the ward for a further 12 hours, after which fluid management, antimicrobials and further investigation were ceased. He died the following day.

What uncertainties do we face when declining admission to intensive care?Read More »