Antecedents to cardiac arrests in a teaching hospital intensive care unit

BACKGROUND

In hospital cardiac arrests (CA) treated with cardio-pulmonary resuscitation (CPR) outside of the intensive care unit (ICU) have poor outcomes. Most are preceded by deranged vital signs. There are, however, limited studies assessing antecedents to CAs inside the ICU.

OBJECTIVES

To study the antecedents to, and characteristics of CAs in ICU.

STUDY POPULATION

We prospectively identified CA cases that occurred inside our ICU between January 2010 and July 2012. Controls were obtained by sequentially matching ICU patients based on APACHE III diagnosis, APACHE III score, age, gender and length of stay in ICU.

RESULTS

Thirty-six patients had a CA during the study period (6.28/1000 admissions). In the 12h prior to CA, index patients had higher maximum (22 breaths/min vs. 18 breaths/min, p=0.001) and minimum respiratory rates (16 breaths/min vs. 12 breaths/min, p=0.031), a lower median mean arterial pressure (65 mmHg vs. 70 mmHg, p=0.029) and systolic blood pressure (97 mmHg vs. 106 mmHg, p=0.033), a higher central venous pressure (14 cm H2O vs. 11 cm H2O, p=0.008) and a lower bicarbonate level (20.5 mmol vs. 26 mmol, p=0.018) compared to controls. CA patients also had a higher maximum dose of noradrenaline (norepinephrine) (17.5 mcg/min vs. 8.0 mcg/min, p=0.052) but there was no difference in any other levels of intensive care support. Two-thirds of CA's occurred within the first 48 h of ICU admission. The initial monitored rhythm was non-shock responsive (pulseless electrical activity, bradycardia or asystole) in 26/36 (72%). Return of spontaneous circulation was achieved in 29/36 (80.6%) patients, with 16/36 (44.4%) surviving to hospital discharge.

CONCLUSIONS

In the period leading up to the CA inside ICU, there were signs of physiological instability and the need for higher doses of noradrenaline. Return of spontaneous circulation was achieved in 80%. However, in-hospital mortality was greater than 50%.

Epidemiology and outcomes of acute liver failure in Australia

BACKGROUND

Acute liver failure (ALF) is a life-threatening syndrome with varying aetiologies requiring complex care and multidisciplinary management. Its changing incidence, aetiology and outcomes over the last 16 years in the Australian context remain uncertain.

AIM

To describe the changing incidence, aetiology and outcomes of ALF in South Eastern Australia.

METHODS

The database of the Victorian Liver Transplant Unit was interrogated to identify all cases of ALF in adults (> 16 years) in adults hospitalised between January 2002 and December 2017. Overall, 169 patients meeting criteria for ALF were identified. Demographics, aetiology of ALF, rates of transplantation and outcomes were collected for all patients. Transplant free survival and overall survival (OS) were assessed based on survival to discharge from hospital. Results were compared to data from a historical cohort from the same unit from 1988-2001.

RESULTS

Paracetamol was the most common aetiology of acute liver failure, accounting for 50% of cases, with an increased incidence compared with the historical cohort (P = 0.046). Viral hepatitis and non-paracetamol drug or toxin induced liver injury accounted for 15% and 10% of cases respectively. Transplant free survival (TFS) improved significantly compared to the historical cohort (52% vs 38%, P = 0.032). TFS was highest in paracetamol toxicity with spontaneous recovery in 72% of cases compared to 31% of non-paracetamol ALF (P < 0.001). Fifty-nine patients were waitlisted for emergency liver transplantation. Nine of these died while waiting for an organ to become available. Forty-two patients (25%) underwent emergency liver transplantation with a 1, 3 and 5 year survival of 81%, 78% and 72% respectively.

CONCLUSION

Paracetamol toxicity is the most common aetiology of ALF in South-Eastern Australia with a rising incidence over 30 years. TFS has improved, however it remains low in non-paracetamol ALF.

Advanced Dementia

An 89-year-old male nursing home resident with a 10-year history of Alzheimer’s disease presents with a temperature of 38.3°C, a productive cough, and a respiratory rate of 28 breaths per minute. Nurses report that for the past 6 months he has been coughing at breakfast and having trouble swallowing. He has profound memory deficits, no longer recognizes his daughter (who is his health care proxy), is bedbound, is able to mumble a couple of words, and is unable to perform any activities of daily living. The nurse asks whether he should be hospitalized. How should this patient be evaluated and treated?

An assessment of the triage performance of the efferent arm of the rapid response system

OBJECTIVES

To measure the triage performance of the efferent arm of a rapid response system (RRS) by assessing the 24h outcome of patients triaged to remain on the ward after rapid response team (RRT) review.

METHODS

We performed a retrospective observational study of all consecutive RRS activations between August 2005 and December 2011 in a university-affiliated hospital. Calls involving patients with documented limitations of medical therapy (LOMT) orders were excluded. We determined patients who were triaged to stay on the ward at the end of their first (index) call and analyzed their vital status and location 24h later. Finally, we reviewed medical charts of patients triaged to remain on the ward and had a cardiac arrest and/or died within 24h of RRT review.

RESULTS

We studied 8304 RRT calls. We excluded 1794 calls involving patients with LOMT, 2165 that were repeat calls, 20 where data was missing, 650 where patients were immediately transferred to a high dependency (HDU) or an intensive care unit (ICU) and 92 where calls were rapidly upgraded to cardiac arrest calls. Thus, we identified 3583 index calls at the end of which patients were triaged to remain on the ward. Within 24h, 454 (12.7%) of those had a repeat RRT activation and 378 were transferred to HDU/ICU. 12 (0.3%) suffered a cardiac arrest on the ward. Altogether, 14 (0.4%) patients died within 24h of the index RRT activation. Of those 6 had LOMT applied after the call, 4 had been admitted to ICU in a further call and 6 (0.2%) patients had unexpected cardiac arrest on the ward.

CONCLUSIONS

The rate of unexpected cardiac arrest in the 24h following RRT activation is very low for patients triaged to stay on the ward. Major triage errors by the RRT appear uncommon.

Continuous renal replacement therapy and its impact on hyperammonaemia in acute liver failure

OBJECTIVE

Hyperammonaemia contributes to complications in acute liver failure (ALF) and may be treated with continuous renal replacement therapy (CRRT), but current practice is poorly understood.

DESIGN

We retrospectively analysed data for baseline characteristics, ammonia concentration, CRRT use, and outcomes in a cohort of Australian and New Zealand patients with ALF.

SETTING

All liver transplant ICUs across Australia and New Zealand.

PARTICIPANTS

Sixty-two patients with ALF.

MAIN OUTCOME MEASURES

Impact of CRRT on hyperammonaemia and patient outcomes.

RESULTS

We studied 62 patients with ALF. The median initial (first 24 h) peak ammonia was 132 μmol/L (interquartile range [IQR], 91-172), median creatinine was 165 μmol/L (IQR, 92-263) and median urea was 6.9 mmol/L (IQR, 3.1-12.0). Most patients (43/62, 69%) received CRRT within a median of 6 hours (IQR, 2-12) of ICU admission. At CRRT commencement, three-quarters of such patients did not have Stage 3 acute kidney injury (AKI): ten patients (23%) had no KDIGO creatinine criteria for AKI, 12 (28%) only had Stage 1, and ten patients (23%) had Stage 2 AKI. Compared with non-CRRT patients, those treated with CRRT had higher ammonia concentrations (median, 141 μmol/L [IQR, 102-198] v 91 μmol/L [IQR, 54-115]; P = 0.02), but a nadir Day 1 pH of only 7.25 (standard deviation, 0.16). Prevention of extreme hyperammonaemia (> 140 μmol/L) after Day 1 was achieved in 36 of CRRT-treated patients (84%) and was associated with transplant-free survival (55% v 13%; P = 0.05).

CONCLUSION

In Australian and New Zealand patients with ALF, CRRT is typically started early, before Stage 3 AKI or severe acidaemia, and in the presence hyperammonaemia. In these more severely ill patients, CRRT use was associated with prevention of extreme hyperammonaemia, which in turn, was associated with increased transplant-free survival.

Coagulation abnormalities, bleeding, thrombosis, and management of patients with acute liver failure in Australia and New Zealand

BACKGROUND AND AIM

To study the management of coagulation and hematological derangements among severe acute liver failure (ALF) patients in Australia and New Zealand liver transplant intensive care units (ICUs).

METHODS

Analysis of key baseline characteristics, etiology, coagulation and hematological tests, use of blood products, thrombotic complications, and clinical outcomes during the first ICU week.

RESULTS

We studied 62 ALF patients. The first day median peak international normalized ratio was 5.5 (inter-quartile range [IQR] 3.8-8.7), median longest activated partial thromboplastin time was 62 s (IQR 44-87), and median lowest fibrinogen was 1.1 (IQR 0.8-1.6) g/L. Fibrinogen was only measured in 85% of patients, which was less than other tests (P < 0.0001). Median initial lowest platelet count was 83 (IQR 41-122) × 109 /L. Overall, 58% of patients received fresh frozen plasma, 40% cryoprecipitate, 35% platelets, and 15% prothrombin complex concentrate. Patients with bleeding complications (19%) had more severe overall hypofibrinogenemia and thrombocytopenia. Thrombotic complications were less common (10% of patients), were not associated with consistent patterns of abnormal hemostasis, and were not immediately preceded by clotting factor administration and half occurred only after liver transplantation surgery.

CONCLUSION

In ALF patients admitted to dedicated Australia and New Zealand ICUs, fibrinogen was measured less frequently than other coagulation parameters but, together with platelets, appeared more relevant to bleeding risk. Blood products and procoagulant factors were administered to most patients at variable levels of hemostatic derangement, and bleeding complications were more common than thrombotic complications. This epidemiologic information and practice variability provide baseline data for the design and powering of interventional studies.

Outcome of Acetaminophen-Induced Acute Liver Failure Managed Without Intracranial Pressure Monitoring or Transplantation

Acetaminophen-induced acute liver failure (ALF) may require emergency liver transplantation (LT) in the presence of specific criteria, and its management may also include intracranial pressure (ICP) monitoring in selected patients at high risk of cerebral edema. We aimed to test the hypothesis that management of such patients without ICP monitoring or LT would yield outcomes similar to those reported with conventional management. We interrogated a database of all patients treated in an intensive care unit for acetaminophen-induced ALF between November 2010 and October 2016 and obtained relevant information from electronic medical records. We studied 64 patients (58 females) with a median age of 38 years. Such patients had a high prevalence of depression, substance abuse, or other psychiatric disorders and had ingested a median acetaminophen dose of 25 g. No patient received ICP monitoring or LT. Overall, 51 (79.7%) patients survived. Of the 42 patients who met King's College Hospital (KCH) criteria, 29 (69.0%) survived without transplantation. There were 45 patients who developed severe hepatic encephalopathy, and 32 (71.1%) of these survived. Finally, compared with the KCH criteria, the current UK Registration Criteria for Super-Urgent Liver Transplantation (UKRC) for super-urgent LT had better sensitivity (92.3%) and specificity (80.4%) for hospital mortality. In conclusion, in a center applying a no ICP monitoring and no LT approach to the management of acetaminophen-induced ALF, during a 6-year period, overall survival was 79.7%, and for patients fulfilling KCH criteria, it was 69.0%, which were both higher than for equivalent patients treated with conventional management as reported in the literature. Finally, the current UKRC may be a better predictor of hospital mortality in this patient population.

Patient characteristics, incidence, technique, outcomes and early prediction of tracheostomy in the state of Victoria, Australia

BACKGROUND

Tracheostomy is a relatively common procedure in Intensive Care Unit (ICU) patients.

AIMS

To study the patient characteristics, incidence, technique, outcomes and prediction of tracheostomy in the State of Victoria, Australia.

METHODS

We used data from the Australian and New Zealand Intensive Care Society Adult Patient Database (ANZICS APD) and the Victorian Admitted Episode Dataset (VAED) to identify and match patients who had received a tracheostomy from 2004 to 2014.

RESULTS

Between 1st January 2004 and 30th June 2014, 9750 patients received a tracheostomy with 7670 available for matching and 6010 (78.4%) successfully matched. Of the matched tracheostomy patients, median age was 61years, median APACHE IIIJ score was 66 and overall hospital mortality was 21%. The incidence of tracheostomy almost halved over the decade with more than half of tracheostomies (53.5%) being percutaneous. Hospital mortality of patients receiving a tracheostomy decreased from 26.5% in 2004 to 16.5% in 2014 by an average decrease of 6%/year. No robust model could be developed to predict tracheostomy.

CONCLUSION

The incidence of tracheostomy and the adjusted mortality rate of patients who received a tracheostomy have significantly decreased over a decade. Day of admission information could not be used to predict subsequent tracheostomy.

Characteristics and outcomes of patients with acute liver failure admitted to Australian and New Zealand intensive care units

BACKGROUND

Knowledge about patients with acute liver failure (ALF) in Australia and New Zealand (ANZ) is lacking.

AIMS

To evaluate whether the pattern of ALF would be similar to previous studies and whether, despite potentially low transplantation rates, mortality would be comparable.

METHODS

We obtained data from the ANZ Intensive Care Society Adult Patient Database and the ANZ Liver Transplant Registry for 10 years commencing 2005 and analysed for patient outcomes.

RESULTS

During the study period, 1 022 698 adults were admitted to intensive care units across ANZ, of which 723 had ALF. The estimated annual incidence of ALF over this period was 3.4/million people and increased over time (P = 0.001). ALF patients had high illness severity (Acute Physiology And Chronic Health Evaluation III 79.8 vs 50.1 in non-ALF patients; P < 0.0001) and were more likely to be younger, female, pregnant and immunosuppressed. ALF was an independent predictor of mortality (odds ratio 1.5 (1.26-1.79); P < 0.0001). At less than 23%, the use of liver transplantation was low, but the mortality of 39% was similar to previous studies.

CONCLUSIONS

ALF is a rare but increasing diagnosis in ANZ intensive care units. Low transplantation rates in ANZ for ALF do not appear to be associated with higher mortality rates than reported in the literature.

Difficult intubation managed using standard laryngeal mask airway, flexible fibreoptic bronchoscope and wire guided enteral feeding tube

This case report describes an alternative method of achieving trans-oral intubation in a patient with a difficult airway who was apnoeic secondary to the therapeutic administration of a non-depolarizing neuromuscular blocking drug given to aid laryngoscopy. After attempts to intubate were unsuccessful by means of direct laryngoscopy utilizing various aids including bougies, a standard laryngeal mask airway was used to ventilate the patient and subsequently, with a swivel Y-connector attached in order to maintain PEEP, to aid the passage of a bronchoscope. The flexible guide-wire from an enteral feeding tube was then passed through the suction port of the bronchoscope into the trachea, after which the laryngeal mask airway and bronchoscope were withdrawn. By passing the enteral feeding tube over the guide-wire and then using this as a guide, a cuffed endotracheal tube was inserted into the trachea. The technique described permitted the continuous application of positive airway pressure, which dramatically improved the bronchoscopic view during the crucial step of placing the guide-wire into the trachea. Passing the feeding tube over the guide-wire aided the subsequent passage of the endotracheal tube, by acting as a stiffer and larger diameter guide through the glottis.

ANZICS guiding principles for complex decision making during the COVID-19 pandemic

The global 2019 coronavirus disease (COVID-19) pandemic has led to major challenges in clinical decision making when the demand for intensive care exceeds local capacity. In order to promote consistent, transparent, objective and ethical decision making, the Australian and New Zealand Intensive Care Society (ANZICS) formed a committee to urgently develop guidelines outlining key principles that should be utilised during the pandemic. This guidance is intended to support the practice of intensive care specialists during the COVID-19 pandemic and to promote the development of local admission policies that should be endorsed by health care organisations and relevant local authorities.

Utility of thromboelastography in managing acquired Factor VIII inhibitor associated massive haemorrhage

Disorders of clotting and coagulation are common in the intensive care unit. Diagnosis, treatment and monitoring of these disorders are traditionally based on conventional coagulation tests such as activated partial thromboplastin time (APTT) and international normalised ratio (INR). We present here a patient who developed massive postoperative haemorrhage secondary to an acquired factor VIII inhibitor. The case highlights the utility and sensitivity of thromboelastography (TEG) in the diagnosis of the condition and monitoring the response to therapy.

The effect of three different miniaturized blood purification devices on plasma cytokine concentration in an ex vivo model of endotoxinemia

PURPOSE

A novel type of adsorptive plasma filtering device (ETX-A) capable of removing endotoxin from blood in a single step has recently been developed using nanotechnology.

METHODS

In a miniaturized, ex vivo model of extracorporeal circuits, we tested the capacity to reduce plasma cytokine concentration of ETX-A filters in comparison to standard high-flux (HF) filters, high cut-off (HCO) filters and a control. Blood from six healthy volunteers was spiked with endotoxin and then circulated through closed (ETX-A, control) or open (HF, HCO) circuits. Blood flow was set at 16 ml/min and filtration flow at 1 ml/min. Samples for measurement of IL-1ra and IL-6 were taken at baseline and at 4 hours.

RESULTS

Compared to control (703.3 [850.6] pg/mL), in HCO (383.5 [1144.1] pg/mL) and ETX-A (490.1 [683.2] pg/mL) filters, plasma IL-1ra pooled pre- and postfilter concentrations were lower at the end of the experiment (P=0.002; P=0.050, respectively) whereas, in standard HF filters, IL-1ra concentration was higher than control. HCO showed a trend toward a reduced relative increase in IL-6 concentration from commencement to end of experiment compared to control (P=0.07). After pooling end-of-experiment plasma cytokine values of novel blood purification devices, we found HCO + ETX-A superior to H with regard to reduction of IL-1ra (-27.0 [-20.5]% vs. 8.1 [18.9]%; p<0.001) and IL-6 (-18.0 [38.3]% vs. -1.1 [24.3]%; P=0.050) compared to control.

CONCLUSIONS

HCO and ETX-A appeared to significantly reduce plasma IL-1ra and, when combined, plasma IL-6 concentration as well. It appears desirable to manufacture full-size blood purification devices using this technology and to explore their effect on cytokine removal.

A checklist for streamlining organ donation after cardiac death

There is currently a shortage of organ donors to meet the demands of transplantation waiting lists. In recent years there has been renewed interest in donation after cardiac death in order to increase the pool of potential donors. The Organ and Tissue Authority has recently developed a national policy for donation after cardiac death. We describe here a checklist that is used by our hospital-based staff for organ donation which outlines important steps in the donation after cardiac death process.

Hydroxyethyl starch or saline for fluid resuscitation in intensive care

BACKGROUND

The safety and efficacy of hydroxyethyl starch (HES) for fluid resuscitation have not been fully evaluated, and adverse effects of HES on survival and renal function have been reported.

METHODS

We randomly assigned 7000 patients who had been admitted to an intensive care unit (ICU) in a 1:1 ratio to receive either 6% HES with a molecular weight of 130 kD and a molar substitution ratio of 0.4 (130/0.4, Voluven) in 0.9% sodium chloride or 0.9% sodium chloride (saline) for all fluid resuscitation until ICU discharge, death, or 90 days after randomization. The primary outcome was death within 90 days. Secondary outcomes included acute kidney injury and failure and treatment with renal-replacement therapy.

RESULTS

A total of 597 of 3315 patients (18.0%) in the HES group and 566 of 3336 (17.0%) in the saline group died (relative risk in the HES group, 1.06; 95% confidence interval [CI], 0.96 to 1.18; P=0.26). There was no significant difference in mortality in six predefined subgroups. Renal-replacement therapy was used in 235 of 3352 patients (7.0%) in the HES group and 196 of 3375 (5.8%) in the saline group (relative risk, 1.21; 95% CI, 1.00 to 1.45; P=0.04). In the HES and saline groups, renal injury occurred in 34.6% and 38.0% of patients, respectively (P=0.005), and renal failure occurred in 10.4% and 9.2% of patients, respectively (P=0.12). HES was associated with significantly more adverse events (5.3% vs. 2.8%, P<0.001).

CONCLUSIONS

In patients in the ICU, there was no significant difference in 90-day mortality between patients resuscitated with 6% HES (130/0.4) or saline. However, more patients who received resuscitation with HES were treated with renal-replacement therapy. (Funded by the National Health and Medical Research Council of Australia and others; CHEST ClinicalTrials.gov number, NCT00935168.).

Registrar triage, communication and moral distress during end-of-life care rapid response team calls in a teaching hospital

BACKGROUND

Approximately one-third of rapid response teams (RRT) involve end-of-life care (EOLC) issues. Intensive care unit (ICU) registrar experience in such calls is underinvestigated.

AIMS

To evaluate the proportion of RRT calls triaged as relating to EOLC issues, issues around communication regarding prognostication, registrar self-reported moral distress and associations between RRT EOLC classification and patient outcomes.

METHODS

Prospective observational study of RRT calls in a tertiary referrals hospital between December 2016 and January 2017 using a standardised case report form and data from an electronic RRT database.

RESULTS

There were 401 RRT calls in the study period, and data were available for 270 (67%) calls, of which 72%, 10% and 18% were triaged as 'obviously not EOLC call', 'obvious EOLC call' and 'uncertain EOLC call' respectively. Most discussions regarding prognostication occurred between registrars, and more than half (55%) were with a covering doctor. Consensus on prognostication was achieved in 93% cases. Registrars reported distress in 19% of calls that obviously related to EOLC and 22% of calls that were uncertain, compared with <1% of calls that were obviously not relating to EOLC. Inhospital mortality was 6%, 67% and 39% for obviously not EOLC, obvious EOLC and uncertain EOLC calls respectively.

CONCLUSIONS

EOLC issues occur commonly in RRT calls and are often associated with moral distress to ICU registrars. Although consensus on prognostication is usually achieved, conversations often involve covering doctors. These issues impact on the ICU registrar experience of RRT calls and require further exploration.

Organisation and resource management in the intensive care unit: A critical review

Background/Aim:

Patients are admitted to an intensive care unit (ICU) for critical care not available to patients in the general wards, with the potential for reversible organ failure as a key admission criterion. The objective of this integrative review was to examine and discuss the literature pertaining to the environment of the ICU, including unit organisation, staffing and equipment, that underpins the provision of ICU services. This review also aimed to discuss current perspectives on ICU resources and utilisation.

Methods:

To prepare this integrated literature review, computer-assisted searches were conducted using the PubMed/Medline, CINAHL and EMBASE databases. An extensive search of library databases was undertaken using relevant keywords and related article searches. Studies were included if they were rated by a single investigator to have relevant content in these areas. Due to the breadth of the review, a structured approach was taken to integrate the relevant findings.

Results:

There was limited literature examining the relationships between these important areas. There was some evidence that a closed model of ICU care is associated with improved outcomes and less resource utilisation compared with an open model of ICU, although there was conflicting evidence for critical care delivered outside of the ICU. Critical care may be most effectively provided via a team model. The heterogeneity of the ICU setting, in particular the unique aspects of the delivery of ICU care in the Australasian model, hampered the ability to draw broad and clinically meaningful conclusions.

Conclusions:

Due to the increased demand for ICU services, ongoing evaluation of the long-term outcomes of ICU on the efficient use of resources to optimise patient outcomes is imperative. Results from the current evidence base suggest that rather than broad-based adjunctive services, refinement and subsequent evaluation of intensive care services in targeted and specific populations may be required, and that empirical evidence for the support of many organisational, structural, equipment and staffing aspects of ICU service delivery is lacking. Further research is needed to investigate the relationships between existing and conceptual models of care and direct patient outcomes.

Fast-track recovery program after cardiac surgery in a teaching hospital: a quality improvement initiative

OBJECTIVE

Fast-track cardiac anesthesia (FTCA) is a technique that may improve patient access to surgery and maximize workforce utilization. However, feasibility and factors impacting FTCA implementation remain poorly explored both locally and internationally. We describe the specific intraoperative and postoperative protocols for our FTCA program, assess protocol compliance and identify reasons for FTCA failure.

RESULTS

We tested the program in 16 patients undergoing elective cardiac surgery requiring cardiopulmonary bypass. There was 100% compliance with the FTCA protocols. Four (25%) patients successfully completed the FTCA protocol (extubated < 4 h postoperatively and discharged from the intensive care unit on the same operative day).

Ammonia and nutritional therapy in the critically ill: when to worry, when to test and how to treat?

PURPOSE OF REVIEW

Hyperammonaemia is almost always develops in patients with severe liver failure and this remains the commonest cause of elevated ammonia concentrations in the ICU. Nonhepatic hyperammonaemia in ICU presents diagnostic and management challenges for treating clinicians. Nutritional and metabolic factors play an important role in the cause and management of these complex disorders.

RECENT FINDINGS

Nonhepatic hyperammonaemia causes such as drugs, infection and inborn errors of metabolism may be unfamiliar to clinicians and risk being overlooked. Although cirrhotic patients may tolerate marked elevations in ammonia, other causes of acute severe hyperammonaemia may result in fatal cerebral oedema. Any coma of unclear cause should prompt urgent measurement of ammonia and severe elevations warrant immediate protective measures as well as treatments such as renal replacement therapy to avoid life-threatening neurological injury.

SUMMARY

The current review explores important clinical considerations, the approach to testing and key treatment principles that may prevent progressive neurological damage and improve outcomes for patients with hyperammonaemia, especially from nonhepatic causes.

Continuous hemofiltration for anasarca: recovery of renal function after 71 liters of net ultrafiltration

We report on a 64-year-old female presenting with anasarca secondary to volume loading in the setting of chronic liver disease, acute on chronic renal failure, circulatory failure and sepsis. Over 37 days, a net negative fluid balance of 71 L was achieved using continuous hemofiltration, with spontaneous recovery of urine output, vasopressor independence and resolution of coagulopathy. This case report underlines the pathophysiological role of tissue edema in the downward spiral of hepato-renal and cardio-renal dysfunction and illustrates that very large volumes of tissue fluid can be safely and effectively removed with continuous renal replacement therapy, thereby permitting recovery of organ function. To our knowledge, there have been no previous reports of such large volume net fluid removal by progressive ultrafiltration in the intensive care unit.

Midodrine use in critically ill patients: a narrative review

Midodrine is a peripherally acting, oral α-agonist that is increasingly used in intensive care units despite conflicting evidence for its effectiveness. It has pharmacological effects on blood vessels as well as pupillary, cardiac, renal, gastrointestinal, genitourinary, lymphatic and skin tissue. It has approval for use as a treatment for orthostatic hypotension, but a surge in interest over the past decade has prompted its use for a growing number of off-label indications. In critically ill patients, midodrine has been used as either an adjunctive oral therapy to wean vasoplegic patients off low dose intravenous vasopressor infusions, or as an oral vasopressor agent to prevent or minimise the need for intravenous infusion. Clinical trials have mostly focused on midodrine as an intravenous vasopressor weaning agent. Early retrospective studies supported its use for this indication, but more recent randomised controlled trials have largely refuted this practice. Key questions remain on its role in managing critically ill patients before intensive care admission, during intensive care stay, and following discharge. This narrative review presents a comprehensive overview of midodrine use for the critical care physician and highlights why lingering questions around ideal patient selection, dosing, timing of initiation, and efficacy of midodrine for critically ill patients remain unanswered.