Author: ICM Case Summaries

Dexmedetomidine Sedation and Delirium

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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?

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Diagnosing Ventilator Associated Pneumonia

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A 64 year old lady who had been admitted with acute pancreatitis due to gallstones. She was initially admitted to the intensive care unit for cardiovascular management and management of her electrolyte imbalance. After a few days she was intubated for hypoxia.

She developed pancreatic necrosis and pseudocyst formation. These were drained by percutaneous drains whereby she showed some improvement with more stability in her cardiovascular system. She had two failed extubations and then had a tracheostomy placed. She was weaned from the ventilator but then remained on 40-45% of oxygen for a number of weeks. Serial scans showed a static nature to her pseudocysts. Her inflammatory markers remained static at a moderate level over this time. It was felt that she had a ventilator associated pneumonia and was started on antibtiotics. She then showed improvement a number of days later. She was further weaned from the ventilator and decannulated. She needed recannulation later and suffered another episode of ventilator associated pneumonia which was treated. Eventually a number of months later she was discharged to the ward and then home.

How can we diagnose ventilator associated pneumonia?

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The Role of Capnography during Cardiac Arrest

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 A 68 year-old gentleman was admitted to the Emergency Department in cardiac arrest. He had complained of sudden onset upper abdominal pain to his wife immediately prior to a collapse, and bystander cardiopulmonary resuscitation (CPR) was commenced whilst emergency services were called. He had a background of ischaemic heart disease, insulin-dependent diabetes, peripheral vascular disease and hypertension.

On arrival, the Paramedic crew found him to be in ventricular fibrillation was the predominant rhythm. Despite appropriate advanced life support with defibrillation and administration of adrenaline and amiodarone over multiple cycles. His airway was supported with an I-Gel supraglottic airway device, and he was transferred to hospital urgently.

Ischaemic heart disease is the leading cause of death in the world, and sudden cardiac arrest is responsible for more than 60% of adult deaths from coronary heart disease. Early and effective CPR, early defibrillation and physiological support post-resuscitation form the chain of survival [1].

Assessment of the patient’s airway on arrival in the Emergency Department revealed evidence of vomit in the pharynx, and endotracheal intubation was performed. Vomitus was aspirated from his endotracheal tube, indicating pulmonary aspiration either at the time of collapse or during the resuscitation attempts. Sidestream capnography was connected to a self-inflating bag administering high-concentration oxygen. The initial capnography indicated a flattened end tidal carbon dioxide (EtCO2) trace with a highest partial pressure of 1.5 kPa. Chest auscultation was performed and air entry was confirmed as being equal bilaterally.

Chest compressions continued uninterrupted and by this stage the overall resuscitation attempt had been ongoing for 45 minutes. The rhythm had changed to pulseless electrical activity, and despite effective CPR, administration of adrenaline and fluids, there was no return of spontaneous circulation (ROSC). Blood gas analysis revealed a severe metabolic acidosis (pH 6.8, lactate 15.2 mmol/L) and by this stage the highest EtCO2 recorded was 0.9 kPa. Following discussion with the team, and on the grounds of futility, the resuscitation attempt was abandoned.

What is the role of capnography in cardiac arrest?

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The Role of Antibiotics in Acute Pancreatitis

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A 65-year-old woman was admitted with a two-day history of feeling non-specifically unwell, severe upper abdominal pain, anorexia and vomiting. On examination she was tachycardic, hypotensive with epigastric tenderness and guarding. Admission amylase was 1024 mmol/L. A diagnosis of acute pancreatitis was made and she was admitted for conservative management with IV fluids and analgaesia. Her initial Ranson score was 3 placing her at moderate risk of of death. Abdominal ultrasound scanning showed a swollen pancreas with a small amount of free fluid but no gallstones or obstruction to the biliary system. Over the next twelve hours she deteriorated on the ward, developing type 1 respiratory failure for which she was referred to intensive care.

On admission to ITU she was semi-electively intubated and ventilated. A low-dose infusion of noradrenaline required to achieve adequate mean arterial pressure. A CT scan showed inflammatory changes and free fluid around the pancreas with possible early pseudocyst formation but no necrotic areas. Two hours after admission she became pyrexial at 39.5°C with a modest increase in her noradrenaline requirements. Peripheral blood cultures were taken and empirical imipenem started following discussion with microbiology. Subsequent repeated microbiological cultures of blood, ascitic fluid, urine and sputum were negative. A nasojejunal tube was passed to allow enteral feeding.

Over the next 48 hours her sedation was weaned and her respiratory function improved. Vasculitis screens, viral serology, lipids, etc. were all negative or normal. Despite her clinical improvement she remained pyrexial with an elevated CRP and white cell count. Further microbiological sampling was unhelpful, serum procalcitonin middling and repeat CT scan showed maturation of her pseduocyst. Fine needle aspiration was performed and subsequently proved culture negative. Her imipenem was stopped after 7 days after gradual resolution of her noradrenaline requirements. Surgical tracheostomy was performed on day 11 to facilitate ventilatory weaning and she was discharged to the ward on day 21.

What is the role for antibiotics in acute pancreatitis?Read More »

Decompressive Craniotomy in Traumatic Brain Injury

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A 20 year-old man was admitted to his local district hospital with a severe head injury following an assault. On arrival in the Emergency Department he was agitated with a reduced conscious level, with evidence of blunt trauma to the head and neck. Prior to intubation, his Glasgow Coma Score (GCS) was recorded as 7 (E1V2M4), and with cervical spine precautions he underwent intubation with subsequent mechanical ventilation and sedation.

An urgent CT brain and cervical spine revealed early evidence of intracerebral contusions with diffuse areas of petechial intracerebral haemorrhage identified. Nasal and maxillary fractures were also seen, with no cervical spine pathology identified. He was transferred to the regional neurological centre for assessment and ongoing management.

On arrival in the Neurosurgical Intensive Care unit the patient underwent insertion of an intracranial pressure monitor revealing an intracranial pressure (ICP) of between 30-35 mmHg. Pupil reactivity was sluggish bilaterally. Sedation was changed to infusions of propofol, fentanyl and midazolam, positioning was optimised with 20 degree head-up tilt, endotracheal tube ties were replaced and targeted mechanical ventilation to EtCO2 4- 4.5kPa. Central venous access was established and an infusion of Noradrenaline was used to target cerebral perfusion pressure to 70mmHg.

Initial medical management stabilised ICP below 25mmHg, but within the next 12 hours this began to rise despite neuromuscular blockade and infusion of hypertonic saline. Further CT imaging revealed progression of the intracerebral contusions with developing oedema. The patient was transferred to the operating theatre for insertion of an external ventricular drain. CSF drainage resulted in an immediate but small improvement in ICP but again over the next 12 hours it began to rise, and decision was made for bifrontal decompressive craniectomy.

Subsequent recovery was slow and was complicated by ventilator-associated pneumonia, a protracted tracheostomy wean and severe agitation. The patient underwent intensive neuro-rehabilitation and had been decannulated, but was left with persistent cognitive impairment, seizures and depression.

What is the rationale for performing decompressive craniotomy in TBI?

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Mechanical Ventilation of Chronic Obstructive Airways Disease

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A 68-year-old went into respiratory arrest on the chest ward. He had been admitted 2 weeks previously for an exacerbation of chronic obstructive airways disease (COAD). He has had two previous episodes of reduced conscious level due to hypercapnoea, which resolved with non-invasive ventilation and oxygen titration.

He was immediately intubated on the ward and transferred to the intensive care unit for ventilation. Hypoxia was corrected to a PaO2 >8.0kPa with a moderate FiO2. However he remained very difficult to ventilate and maintained a persistently high PaCO2. The highest level was 21kPa. He was treated with B2 agonist nebulisers, anti-muscarinic nebulisers, systemic steroids, aminophylline infusions, magnesium infusions and a ketamine infusion. He also needed vasopressor support and for a period of time continuous renal replacement therapy. After a week when his ventilator pressures reduced he had an uneventful percutaneous tracheostomy. Sedation was then reduced and he was awake and spontaneously breathing but with a high level of support. He was recurrently troubled by episodes of bronchospasm and air trapping. The lowest settings for inspiratory pressure were 14 cmH2O. He deteriorated a number of times before care was withdrawn and he died 20 days later.

Can we predict which COAD patients will benefit from mechanical ventilation?

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Intra-Aortic Balloon Pump for Cardiogenic Shock

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A previously healthy 58-year-old male was admitted to hospital following an OOH cardiac arrest. The initial cardiac rhythm was VF. He remained on the ‘shockable’ side of the ALS algorithm and was managed accordingly with defibrillation and intravenous adrenaline.  ROSC occurred after 28 minutes. A 12-lead ECG showed a STEMI in the antero-septal territories.

Coronary angiography showed a proximal occlusion of the left anterior descending artery through which a drug eluting stent was inserted. Despite this and adrenaline (10-20mcg) boluses, the patient remained persistently acidotic and hypotensive. A diagnosis of cardiogenic shock was made and an intra-aortic balloon pump (IABP) was inserted via the left common femoral artery with subsequent improvement in haemodynamic parameters. The patient was transferred to a cardiothoracic critical care.

Transthoracic echocardiography showed a globally hypokinetic left ventricle (LV) with an ejection fraction (EF) of approximately 20%. Within the first 6 hours, he developed runs of non-sustained VT and frequent ventricular ectopics, which interfered with IABP triggering causing worsening haemodynamic instability. Triggering was switched from ECG to arterial pressure. Electrolytes were supplemented and intravenous amiodarone was commenced to manage the dysrhythmias. Targeted temperature management to 36 degrees Celsius for 24 hours was initiated. Anticoagulation for IABP was commenced and peripheral pulses were regularly monitored.

His dysrhythmias resolved with subsequent improvement of IABP performance. On day 3, the IABP was weaned to 1:2 ratio for approximately 6 hours and removed. A tracheostomy was inserted on day 7 and the patient underwent long term respiratory wean and neurological rehabilitation.

Describe the indications, contraindications, complications and basic principles of intra-aortic balloon counterpulsation balloon pump.Read More »

Sleep Deprivation on the ICU

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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?

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Enteral vs Parenteral Feeding on ICU

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A 70-year-old man had been an inpatient on the intensive care unit for nearly 40 days after a complicated recovery following mitral valve replacement. He was being gradually weaned from the ventilator via tracheostomy but required no other invasive organ support. His intensive care unit stay had been complicated by recurrent respiratory sepsis treated with antibiotics and aggressive physiotherapy. Up until this point he had been fed by a nasogastric tube but began to exhibit signs suggestive of impaired absorption including large nasogastric aspirates and a requirement for higher levels of parenteral electrolyte administration.

Prokinetic treatment with metoclopramide 10mg TDS for 24 hours failed to improve the high aspirate levels which remained in excess of 300ml every four hours. Erythromycin 250mg BD was added with little improvement. Following discussion with gastroenterology colleagues an agreement to place a post-pyloric nasojejunal feeding tube was made; unfortunately this procedure was delayed by a further 48 hours as no endoscopist was free to attend. Parenteral feeding was initiated at this point in order to maintain calorific intake.

Compare enteral and parental nutrition.Read More »

Echocardiography on ICU

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A 50 year old female presented with acute kidney injury and sepsis.  She required fluid resuscitation, haemofiltration and cardiovascular support for 2 days, following which she was discharged to the renal ward for on-going haemodialysis. She underwent dialysis every 2-3 days for the next 3 weeks. Whilst on the ward she deteriorated acutely one evening, developing respiratory distress, followed by a respiratory arrest. She was intubated and ventilated transferred to the critical care unit.

A CTPA was negative for pulmonary embolus, but showed large bilateral pleural effusions. Tracheal suctioning was initially clear but later copious blood stained secretions were removed. A bedside cardiac echo performed by the consultant intensivist showed a globally sluggish left ventricle, which was overfilled, and the inferior vena cava measured 3cm also suggesting fluid overload. A trial of furosemide failed and she was aggressively haemofiltered to remove the excess fluid. Troponin was only mildly raised, and not thought to be suggestive of an acute cardiac event. She was extubated 24 hours later, but had two further episodes of flash pulmonary oedema requiring non-invasive ventilatory support whilst haemofiltration was re-commenced for fluid balance reasons. In total twelve litres of fluid were removed, with significant improvement in the patient’s condition. Repeat echocardiography prior to discharge showed an improving left ventricular function and IVC measurement of 2cm with greatly increased compliance.

What is the evidence that focussed echocardiography helps guide decision-making in intensive care?Read More »