Category: 7.3

Manages sedation and neuromuscular blockade

Propofol Infusion Syndrome

ICM Case Summaries1 Comment

A 28-year-old man was involved in a high-speed road traffic accident suffering severe head injury (diffuse axonal injury) with bilateral haemopneumothoraces and pulmonary contusions. He was transferred intubated and ventilated to the neurointensive care unit from a district general hospital for intra-cranial pressure (ICP) monitoring.

He was initially managed with bilateral chest drains and conservative neuroprotective measures for difficult to control ICP. He was heavily sedated on propofol (300mg/hr), midazolam (30mg/hr) and fentanyl (300mcg/hr).

Over the next few days his temperature increased and he became increasingly hypoxic. He subsequently developed ECG changes and a echocardiogram showed right heart failure. A diagnosis of pulmonary embolism, which was confirmed on CTPA a few days later which showed evidence of a small PE. He was not anticoagulated due to neurosurgical concern regarding his head injury.

Over the next few days he developed renal failure requiring renal replacement therapy and acute liver failure with hypoglycaemia and lactic acidosis. He developed severe cardiovascular failure requiring multiple inotropes and pulmonary artery catheter guided therapy. Lipids were found to be elevated, with creatine kinase >50,000 and myoglobin found in the urine. Propofol infusion syndrome was diagnosed. Sedation was stopped and he started to make a recovery.

What are the clinical features of propofol infusion syndrome?

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Intra-Abdominal Hypertension

ICM Case Summaries1 Comment

 

A 48 year old male was admitted to the ICU with rapidly evolving multi-organ dysfunction. He was in type I respiratory failure, hypotensive and had stage II acute kidney injury. He had been an inpatient recovering from a laparotomy for major urological surgery 5 days prior to his ICU admission. This was complicated by a major intraoperative haemorrhage.

The patient was commenced on treatment for presumed hospital acquired pneumonia. He was placed on mechanical ventilation and a noradrenaline infusion was commenced to maintain a mean arterial pressure of ≥65mmHg. Over the following 24 hours the patient displayed worsening lung compliance in the context of adequate oxygenation and an atracurium infusion was started. Simultaneously the patient appeared to develop an ileus and he became anuric. Repeated clinical examination revealed an increasingly distended abdomen. A CT of the abdomen and pelvis showed a large left sided retroperitoneal haematoma with evidence of pelvico-ureteric leak on the left and an associated fluid collection. The patient was taken to theatre for urgent re-laparotomy.

At the conclusion of the operation, the surgical team was unable to close the abdomen due to significant bowel oedema. They accepted a laparostomy and returned the patient to ICU with a negative pressure wound dressing in-situ. Post-operatively, there was significant improvement in lung compliance, vasopressor requirement and urine output. Enteral feeding was quickly re-established. The abdomen was closed during the same hospital admission and the patient survived-to-discharge home. At no point was this patient’s intra-abdominal pressure measured.

 

Describe the management of intra-abdominal hypertension.

Christopher Westall

Intra-abdominal hypertension (IAH)- abdominal compartment syndrome (ACS) is a well-recognised cause of morbidity and mortality in critically ill patients, rising to prominence in the 1990s with increased early survival of patients with intra-abdominal pathology requiring emergent laparotomy (principally abdominal aortic aneurysm repair and blunt trauma).1,2 IAH/ ACS may be precipitated by a range of insults local (primary IAH) and distant (secondary IAH) to the abdomen.3 The syndrome encompasses a spectrum of severity and there are a range of treatment options, though with little high quality evidence to support these.

The World Society of the Abdominal Compartment Syndrome (WSACS) consensus guidelines recommend that intra-abdominal pressure (IAP) is measured using the trans-bladder technique in any critically ill patient with an associated risk factor for IAH. The normal value for IAP is <12mmHg. IAH is then categorized by increasing pressure increments from grade I (IAP 12-15mmHg) to grade IV (>25mmHg). Abdominal compartment syndrome is defined as sustained IAP >20mmHg associated with new organ dysfunction.3

The WSACS Consensus proposes a management algorithm for IAH/ ACS that is loosely analogous to commonly encountered algorithms for managing raised intracranial pressure The abdomen is considered a fixed compartment with intra-luminal and extra-luminal volumes that can be manipulated through neutral-negative fluid balance, nasogastric and colonic decompression and percutaneous drainage of ascites/collections. In this instance, however, the compliance of the “box”, the abdominal wall, can also be manipulated by patient position, ventilatory strategy and neuromuscular blockade. Decompressive [laparotomy] therapy is reserved for algorithm failure.3 

The efficacy of protocolised management of IAH/ACS has never been demonstrated. A single prospective observational study suggested reduction in morbidity and mortality using algorithm based management of IAH; the authors quoted an increase in survival-to-discharge rate from 50 to 72% (p= 0.015) across 6 years with improved rates of same-admission closure. However the study was single centre, recruiting patients only after the laparostomy, with substantial selection and observer bias. Furthermore it was unclear which parts of the protocol were effective.4 While the basic principles underlying the WCASC 2013 algorithm are sensible, it must be acknowledged that proposed therapies such as resuscitation with hypertonic fluids, diuretic-driven diuresis and ultrafiltration through renal replacement therapies have no evidence to support them and have potentially serious implications for the patient.

Given that the efficacy of protocolised management of IAH/ACS is uncertain, is there then any evidence to support the measurement of IAP in every “at risk” patient, especially since the list of risk factors for IAH is so extensive that it is difficult to imagine a critically ill patient that is not at risk. This would not be without significant task-burden to critical care nursing staff, and as with any clinical index in ICU, risks morbidity from misinterpretation. There are only two small studies that have examined whether clinical examination can reliably predict intra-abdominal pressure; both small studies with significant methodological flaws and both conducted between 1996- 2000 when awareness of IAH was comparatively low. Importantly both studies compared examination to IAP measurement at pressures well below 20mmHg, where there is little evidence that specific intervention improves patient outcome, beyond highlighting that that patient is at risk of ACS.5,6

Decompressive laparotomy is recommended for the treatment of all patients with ACS refractory to medical therapy.3 In modern practice it is difficult to accurately assess the performance of this strategy in primary IAH/ACS, such is the absence of clinical equipoise. As many reviews acknowledge, the improvement in patient survival rates associated with primary laparostomy in abdominal trauma patients in the 1990s caused a fundamental paradigm shift from which it is now difficult to ethically justify alternative treatment strategies.1,2 That is to say that many patients with IAH/ ACS will now present to the ICU once decompressive laparostomy has either occurred or is imminently planned.

The benefits of decompressive laparotomy in secondary ACS are certainly less; data exists only for acute severe pancreatitis and sepsis associated with secondary peritonitis. While in both instances it must be acknowledged that laparostomy reduces IAP, like many interventions in a critically ill patient population, this does not translate into mortality benefit.7,8 As commentators note, laparostomy may often be performed because of a conceptual benefit of relook-laparotomy 48 hours later, rather than inability to close the abdomen or specific concerns regarding ACS.2 Indeed, regarding secondary peritonitis, there is good evidence that primary closure with on-demand re-laparotomy is non-inferior to laparostomy and planned re-laparotomy, and is associated with fewer surgeries and lower healthcare costs.9 This strategy is now [weakly] endorsed by the WCACS.3

One point that is widely agreed upon is the management of laparostomy. It appears universally agreed that negative pressure wound therapy (NPWT, i.e. “vac dressings”), with or without a form of dynamic retention system, is superior to previously popular methods such as bioprosthetic mesh and Bogota bag. The largest systematic review on the subject suggests that NPWT is associated with improved rates of primary delayed fascial closure (57.8%, 95% CI 50.8- 64.7) and mortality (22.3%, 95% CI 17.5- 27.5) with lower rates of entero-atmospheric fistulation (7.0%, 95% CI 5.0- 9.3) and abscess formation (4.2%, 95% CI 2.3- 6.9).10 This systematic review heavily influenced the most recent NICE review on the topic leading to endorsement of NPWT in clinical guideline IPG467, “Negative pressure wound therapy for the open abdomen” (2013).

Conclusion

The measurement of IAP in all at-risk critically ill patients is probably unnecessary and burdensome in resource terms. Critical care practitioners should have a low index of suspicion for ACS in their patients; if this develops then decompressive laparotomy is the treatment of choice (unless there is a large extra-luminal collection amenable to urgent drainage), particularly since modern laparostomy management appears to be associated with an increasingly low complication rate, if the abdomen cannot be closed.

The consensus guidelines for IAH/ACS remind us that attention to detail; such as ensuring that enteral nutrition is succeeding, that bowel care is optimal and that fluid balance is tightly controlled, may prevent numerous serious ICU-associated syndromes from ever developing.

References

1. Balogh ZJ, Lumsdaine W, Moore EE, Moore FA. Postinjury abdominal compartment syndrome: from recognition to prevention. Lancet,  2014; 384:1466-75

2. Leppaniemi AK. Laparostomy: why and when? Critical Care 2010; 14: 216. DOI: 10.1186/cc8857

3. Kirkpatrick AW, Roberts DJ, De Waele J, Jaeschke R, Malbrain MLNG, De Keulenaer B, Duchesne J, Bjorck M, Leppaniemi A, Ejike JC, Sugrue M, et al.  Intra-abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome. Intensive Care Med, 2013; 39:1190-1206

4. Cheatham ML, Safcsak KRN. Is the evolving management of intra-abdominal hypertension and abdominal compartment syndrome improving survival? Crit Care Med,  2010; 38:402-407

5. Kirkpatrick AW, Brenneman FD, McLean RF, Rapanos T, Boulanger BR. Is clinical examination an accurate indicator of raised intra-abdominal pressure in critically injured patients? Can J Surg, 2000:43:207-11

6. Sugrue M, Bauman A, Jones F, Bishop G, Flabouris A, Parr M, Stewart A, Hillman K, Deane SA. Clinical examination is an inaccurate predictor of intra-abdominal pressure. World J Surg, 2002; 26:1428-31

7. Mentula P, Hienonen P, Kemppainen E, Puolakkainen P, Leppaniemi A. Surgical decompression for abdominal compartment syndrome in severe acute pancreatitis. Arch Surg, 2010; 145:764-9

8. Robledo FA, Luque-de-Leon E, Suarez R, Sanchez P, de la Fuente M, Vargas A, Mier J. Open versus closed management of the abdomen in the surgical treatment of severe secondary peritonitis: a randomized clinical trial. Surg Infect (Larchmt), 2007; 8:63–72

9. van Ruler O, Mahler CW, Boer KR, Reuland EA, Gooszen HG, Opmeer BC, de Graaf PW, Lamme B, Gerhards MF, Steller EP, van Till JW, et al. Comparison of on-demand vs planned relaparotomy strategy in patients with severe peritonitis: a randomized trial. JAMA, 2007; 298:865-73

10. Quyn AJ, Johnston C, Hall D, Chambers A, Arapova N, Ogston S, Amin AI. The open abdomen and temporary abdominal closure systems- historical evolution and systematic review. Colorectal Dis, 2012; 14: e429–38

 

Alpha-2 agonists for sedation

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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.

 

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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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Sleep Deprivation on the ICU

ICM Case Summaries1 Comment

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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Management of Delirium

Management of Delirium

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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 »