Alpha-2 agonists for sedation

 

A 66 year old woman was admitted to the ICU with acute type II respiratory failure secondary to a community acquired pneumonia (CURB-65 score 4) complicating severe COPD (FEV1 40% predicted). Collateral history revealed many concerning features; the patient had a poor exercise tolerance (mMRC dyspnoea scale score 3, exercise tolerance <100m), was alcohol dependent (drinking 120 units per week) and previously had been admitted to hospital with an exacerbation of COPD requiring NIV, and treatment for acute alcohol withdrawal.

 

Mechanical ventilation was commenced using a lung-protective strategy with permissive hypercapnia. Sedation was achieved using remifentanil and propofol, targeting a Richmond Agitation Scale Score (RASS) of -2 to 0. A noradrenaline infusion was commenced to maintain a mean arterial pressure of ≥65mmHg. A neutral cumulative fluid balance was targeted. Broad-spectrum antimicrobial therapy was continued as per local antimicrobial guidelines. Intravenous B vitamins were administered and enteral feeding was established via a nasogastric tube.

In view of the patient’s comparatively poor pre-morbid function and high risk of delirium, early extubation to NIV was identified as the preferred strategy. By day 3 the patient had improved such that this became a realistic goal. In order to prevent acute alcohol withdrawal, yet use benzodiazepines sparingly to avoid associated respiratory depression, remifentanil-propofol sedation was substituted for a clonidine infusion, which was continued following extubation. Low doses of chlordiazepoxide were used as rescue therapy in accordance with Clinical Institute Withdrawal Assessment for Alcohol scale (CIWA-Ar) scoring.

The patient progressed well, was weaned from both NIV and clonidine and was discharged from HDU to a respiratory ward on day 8. She survived to hospital discharge.

 

What role do Alpha-2 Agonists have for sedation in critical care?Read More »

Advertisements

Dexmedetomidine Sedation and Delirium

A 35-year-old man was admitted through the Emergency Department with a three-day history of sore throat, drooling of saliva and fever. In the twenty-four hours leading up to his admission he had reported increasing difficulty breathing and hoarseness. His past medical history included obesity and non-insulin dependent diabetes mellitus.

On initial assessment he was found to be stridulous, drooling, tachypnoeic, tachycardic and febrile. Supplemental oxygen was applied and intravenous access obtained, with blood cultures being sent prior to administration of broad-spectrum antibiotics (Ceftriaxone, Benzylpenicillin and Metronidazole). Despite nebulised Adrenaline, intravenous fluid and intravenous dexamethasone, he continued to deteriorate and was transferred to the anaesthetic room for definitive airway management. Findings at intubation were consistent with acute epiglottitis. Swabs were taken and oral fibreoptic intubation was successfully performed.

Following admission to the ICU, he was mechanically ventilated and sedated with infusions of Propofol and Remifentanil. Antibiotic therapy was continued and he was commenced on regular dexamethasone to reduce epiglottic oedema. He required a low- dose noradrenaline infusion to maintain blood pressure, and was commenced on an insulin sliding scale. Two days after admission his airway was reassessed with direct laryngoscopy, and was found to be significantly less oedematous.

At this stage a sedation hold was performed, with the patient opening eyes spontaneously and seeming to obey commands. He was extubated to humidified facemask oxygen but shortly afterwards became agitated, combative and delirious (CAM-ICU positive). The patient was re-intubated within a two-hour period and Propofol and Remifentanil sedation was recommenced. Over the following two days, he remained inappropriate on daily sedation holds, and by this stage was receiving bolus doses of Haloperidol for episodes of acute agitation. CT imaging of his brain revealed no abnormality, and lumbar puncture was negative for central nervous system infection. Intravenous dexamethasone had been weaned, in view of the improvement in epiglotittis seen at laryngoscopy.

By day six of his admission he remained neurologically inappropriate on sedation hold, and was changed to an intravenous infusion of Dexmedetomidine at 0.7 mcg/kg/hr. Remifentanil was weaned off at this time, and Propofol infusion was reduced to baseline levels. This continued for a further twenty-four hours, by which time he was neurologically appropriate on sedation hold, obeying commands, and was extubated uneventfully.

On direct questioning, the patient did not recall his first extubation episode on Intensive Care. He did recall a combination of vivid visual and auditory hallucations, including the presence of insects in his bed, hearing persecutory voices and a feeling of helplessness and fear. He made a full recovery, and these symptoms had fully resolved by the time he was discharged from hospital.

What is the role of dexmedetomidine in the prevention and management of ICU delirium?

Read More »

Sleep Deprivation on the ICU

A 70-year-old lady was admitted to the Intensive Care Unit (ICU) with respiratory failure and septic shock secondary to pneumococcal pneumonia. She developed multi- organ failure, requiring a prolonged period of mechanical ventilation and weaning, and also developed acute kidney injury requiring haemofiltration. Once a tracheostomy was performed and sedative infusions weaned, she was noted to be acutely delirious. Her sleep pattern was severely disrupted, with extended periods of nighttime wakefulness and sleep fragmentation, increased daytime sleep and difficulty with sleep initiation requiring pharmacological intervention.

Following exclusion of organic causes including CT brain imaging, the delirium was managed with a combination of antipsychotic medications including haloperidol, mirtazapine and quetiapine. Benzodiazepine-based night sedation was used but found to be ineffective in establishing sustained sleep.

A trial of night sedation with infusion of Propofol did not have any ongoing or long-lasting benefit other than the immediate sedative effects and providing control of agitation. A trial of Dexmedetomidine infusion also yielded similar results, although a more sustained daytime anxiolytic effect was noted. Benzodiazepine therapy was changed to supplementation of Melatonin. At around this time, the delirium began to resolve and the patient was able to more actively engage in physiotherapy and patient care. By the time of ICU discharge over thirty days later, and following successful weaning and decannulation, the patient’s sleep pattern had improved significantly.

What are the implications of sleep deprivation in the critically ill patient and how can it be managed?

Read More »

Post Operative Cognitive Deficit after Cardiac Surgery

A middle-aged  man underwent an elective re-do aortic arch replacement for a 6.1cm ascending aortic aneurysm distal to a pre-existing composite graft. Past medical history included a Bentall procedure (metallic aortic valve replacement, aortic root and ascending aorta replacement with coronary re-implantation into the composite graft) 20 years ago. Preoperative echocardiogram showed a well seated AVR and good biventricular function. Drug history included Warfarin (target INR 2-3) and Atenolol.

Anaesthetic induction and re-sternotomy were uneventful. Cerebral oximetry (rSO2) monitoring was utilized in this case. Cardiopulmonary bypass (CPB) was achieved uneventfully and deep hypothermic circulatory arrest (DHCA) was instituted. The patient was cooled to 18°C using CPB and icepacks. Prior to CPB and DHCA being commenced, intravenous thiopentone and methylprednisolone were administered for neuroprotection. Total DHCA time was 40 minutes and selective anterograde perfusion via the right axillary artery (chosen as it is relatively free of atheroma) was employed when rSO2 dropped to <40% and they remained >40% for the remainder of DHCA. Total CPB time was 105 minutes.

Following successful insertion of a new graft, the patient was carefully rewarmed to normothermia and weaned off CPB uneventfully, only requiring minimal vasopressor support. The patient was transferred to the cardiothoracic critical care unit.

After optimization of cardiorespiratory physiology, correcting coagulopathy and maintaining normothermia, with strict avoidance of hyperthermia, the patient was extubated the following day. For the first 48-72 hours postoperatively, delirium was the most active medical issues and this was managed according to conventional treatment. There was no focal upper or lower limb neurology. The patient did not require any other organ system support.

Following resolution of his delirium the patient was discharged to the ward to continue his rehabilitation. Prior to discharge, at approximately postoperative days 7-10, he was complaining of loss of short-term memory, reduced attention span and difficulty with finding words. A neurology review attributed this to cognitive dysfunction but no formal tests were carried out. A neurology clinic follow-up and an outpatient MRI scan were arranged.

What are the neurological complications after cardiac surgery?Read More »

Delirium

Delirium

A patient underwent a laparotomy due to bowel perforation with peritonitis and septic shock and required ventilation for several days. He was sedated with midazolam and fentanyl. After extubation he became agitated overnight, pulled out his invasive monitoring lines and was attempting to climb out of bed.

How should his acute confusional state be managed?Read More »

Delirium on the ICU

Delirium on the ICU

A 67 year old with signficant cardiovascular comorbidities presented with a fractured neck of femur after a fall. She had a hemiarthroplasty performed under GA with fascia iliaca blocks, and went to HDU postoperatively. She became acutely confused during the first postoperative night with hallucinations and paranoia. She was CAM-ICU positive and was given haloperidol to control her agitation.

What is the optimum management of delirium on the ICU?Read More »

Management of Delirium

Management of Delirium

A large 60 year old man developed septic shock and multiorgan failure secondary to a severe community acquired pneumonia. On the twelfth night of his ICU admission he became increasingly agitated and pulled out his vascath, NG tube and dislodged his tracheostomy. The resulting loss of airway led to a severe desaturation event before he was anaesthetised and reintubated, with loss of around 500ml blood from the haemofiltration circuit and vascath wound haemorrhage. He was commenced on regular haloperidol, but his CAM-ICU remained positive for 48 hours. Haloperidol was continued for 4 days, and he had a prolonged respiratory wean.

How is delirium best managed on the intensive care unit?Read More »