Can therapeutic hypothermia trigger propofol-related infusion syndrome?

Propofol for Anesthesia in Pediatric Patients With Epilepsy on the Ketogenic Diet: A Single-Center Experience

BACKGROUND

Propofol use is contraindicated in patients on ketogenic diet (KD) due to higher risk of propofol infusion syndrome (PIS). This study is intended to provide a descriptive analysis of our experience with propofol bolus and short infusions for anesthetic care in patients on the KD and to evaluate if any signs of PIS were observed.

METHODS

All patients on the KD who underwent anesthesia with propofol between 2012 and 2022 were reviewed. Anesthetic encounters and charts were studied for type of surgical procedure; signs of PIS, including new cardiac arrhythmias, acidosis, or rhabdomyolysis in the periprocedural period; hypoglycemia; unplanned admissions within 24 hours of the procedure; if procedure was unexpectedly aborted; and increased seizure frequency within one week.

RESULTS

We identified 65 patients, aged from one to 20 years who underwent 165 anesthetic encounters with propofol, of which 123 were boluses and 42 were infusions. In bolus dosing, the average dose was 2.8 mg/kg (0.7 to 12.8 ± 1.8 mg/kg). Of these, four encounters developed acidosis, one developed rhabdomyolysis, and one developed increased seizures. With infusions, the average infusion rate was 9 mg/kg/hour, with mean infusion duration of 83 minutes (10 to 352 ± 75 minutes). Of these, one developed acidosis and one increased seizures. No cases of PIS were identified. None of the adverse effects were attributed to propofol.

CONCLUSIONS

Boluses and brief infusions of propofol for anesthetic use in patients on the KD did not cause PIS in our cohort.

A meta-analysis of the effects of therapeutic hypothermia in adult patients with traumatic brain injury

Purpose

Therapeutic hypothermia management remains controversial in patients with traumatic brain injury. We conducted a meta-analysis to evaluate the risks and benefits of therapeutic hypothermia management in patients with traumatic brain injury.

Methods

We searched the Web of Science, PubMed, Embase, Cochrane (Central) and Clinical Trials databases from inception to January 17, 2019. Eligible studies were randomised controlled trials that investigated therapeutic hypothermia management versus normothermia management in patients with traumatic brain injury. We collected the individual data of the patients from each included study. Meta-analyses were performed for 6-month mortality, unfavourable functional outcome and pneumonia morbidity. The risk of bias was evaluated using the Cochrane Risk of Bias tool.

Results

Twenty-three trials involving a total of 2796 patients were included. The randomised controlled trials with a high quality show significantly more mortality in the therapeutic hypothermia group [risk ratio (RR) 1.26, 95% confidence interval (CI) 1.04 to 1.53, p = 0.02]. Lower mortality in the therapeutic hypothermia group occurred when therapeutic hypothermia was received within 24 h (RR 0.83, 95% CI 0.71 to 0.96, p = 0.01), when hypothermia was received for treatment (RR 0.66, 95% CI 0.49 to 0.88, p = 0.006) or when hypothermia was combined with post-craniectomy measures (RR 0.69, 95% CI 0.48 to 1.00, p = 0.05). The risk of unfavourable functional outcome following therapeutic hypothermia management appeared to be significantly reduced (RR 0.78, 95% CI 0.67 to 0.91, p = 0.001). The meta-analysis suggested that there was a significant increase in the risk of pneumonia with therapeutic hypothermia management (RR 1.48, 95% CI 1.11 to 1.97, p = 0.007).

Conclusions

Our meta-analysis demonstrated that therapeutic hypothermia did not reduce but might increase the mortality rate of patients with traumatic brain injury in some high-quality studies. However, traumatic brain injury patients with elevated intracranial hypertension could benefit from hypothermia in therapeutic management instead of prophylaxis when initiated within 24 h.

Therapeutic hypothermia to reduce intracranial pressure after traumatic brain injury: the Eurotherm3235 RCT

BACKGROUND

Traumatic brain injury (TBI) is a major cause of disability and death in young adults worldwide. It results in around 1 million hospital admissions annually in the European Union (EU), causes a majority of the 50,000 deaths from road traffic accidents and leaves a further ≈10,000 people severely disabled.

OBJECTIVE

The Eurotherm3235 Trial was a pragmatic trial examining the effectiveness of hypothermia (32-35 °C) to reduce raised intracranial pressure (ICP) following severe TBI and reduce morbidity and mortality 6 months after TBI.

DESIGN

An international, multicentre, randomised controlled trial.

SETTING

Specialist neurological critical care units.

PARTICIPANTS

We included adult participants following TBI. Eligible patients had ICP monitoring in place with an ICP of > 20 mmHg despite first-line treatments. Participants were randomised to receive standard care with the addition of hypothermia (32-35 °C) or standard care alone. Online randomisation and the use of an electronic case report form (CRF) ensured concealment of random treatment allocation. It was not possible to blind local investigators to allocation as it was obvious which participants were receiving hypothermia. We collected information on how well the participant had recovered 6 months after injury. This information was provided either by the participant themself (if they were able) and/or a person close to them by completing the Glasgow Outcome Scale - Extended (GOSE) questionnaire. Telephone follow-up was carried out by a blinded independent clinician.

INTERVENTIONS

The primary intervention to reduce ICP in the hypothermia group after randomisation was induction of hypothermia. Core temperature was initially reduced to 35 °C and decreased incrementally to a lower limit of 32 °C if necessary to maintain ICP at < 20 mmHg. Rewarming began after 48 hours if ICP remained controlled. Participants in the standard-care group received usual care at that centre, but without hypothermia.

MAIN OUTCOME MEASURES

The primary outcome measure was the GOSE [range 1 (dead) to 8 (upper good recovery)] at 6 months after the injury as assessed by an independent collaborator, blind to the intervention. A priori subgroup analysis tested the relationship between minimisation factors including being aged < 45 years, having a post-resuscitation Glasgow Coma Scale (GCS) motor score of < 2 on admission, having a time from injury of < 12 hours and patient outcome.

RESULTS

We enrolled 387 patients from 47 centres in 18 countries. The trial was closed to recruitment following concerns raised by the Data and Safety Monitoring Committee in October 2014. On an intention-to-treat basis, 195 participants were randomised to hypothermia treatment and 192 to standard care. Regarding participant outcome, there was a higher mortality rate and poorer functional recovery at 6 months in the hypothermia group. The adjusted common odds ratio (OR) for the primary statistical analysis of the GOSE was 1.54 [95% confidence interval (CI) 1.03 to 2.31]; when the GOSE was dichotomised the OR was 1.74 (95% CI 1.09 to 2.77). Both results favoured standard care alone. In this pragmatic study, we did not collect data on adverse events. Data on serious adverse events (SAEs) were collected but were subject to reporting bias, with most SAEs being reported in the hypothermia group.

CONCLUSIONS

In participants following TBI and with an ICP of > 20 mmHg, titrated therapeutic hypothermia successfully reduced ICP but led to a higher mortality rate and worse functional outcome.

LIMITATIONS

Inability to blind treatment allocation as it was obvious which participants were randomised to the hypothermia group; there was biased recording of SAEs in the hypothermia group. We now believe that more adequately powered clinical trials of common therapies used to reduce ICP, such as hypertonic therapy, barbiturates and hyperventilation, are required to assess their potential benefits and risks to patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN34555414.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 45. See the NIHR Journals Library website for further project information. The European Society of Intensive Care Medicine supported the pilot phase of this trial.

Propofol infusion syndrome: a structured literature review and analysis of published case reports

Propofol infusion syndrome is a rare, potentially fatal condition first described in children in the 1990s and later reported in adults. We provide a narrative review of what is currently known about propofol infusion syndrome, including a structured analysis of all published case reports; child and adult cases were analysed separately as propofol is no longer used for long-term sedation in children. The review contains an update on current knowledge of the pathophysiology of this condition along with recommendations for its diagnosis, prevention, and management. We reviewed 108 publications documenting 168 cases of propofol infusion syndrome. We evaluated clinical features and analysed factors influencing mortality in child and adult cases using separate multivariate analysis models. We used separate multiple linear regression models to analyse relationships between cumulative dose of propofol and the number of features seen and organ systems involved. Lipidaemia, fever, and hepatomegaly occurred more frequently in children than in adults, whilst rhabdomyolysis and hyperkalaemia were more frequent in adults. Mortality from propofol infusion syndrome is independently associated with fever and hepatomegaly in children, and electrocardiogram changes, hypotension, hyperkalaemia, traumatic brain injury, and a mean propofol infusion rate >5 mg kg^-1 h^-1 in adults. The cumulative dose of propofol was associated with an increased number of clinical features and the number of organ systems involved in adult cases only. Clinicians should consider propofol infusion syndrome in cases of unexplained metabolic acidosis, ECG changes, and rhabdomyolysis. We recommend early consideration of continuous haemofiltration in the management of propofol infusion syndrome.

Effect of Early Sustained Prophylactic Hypothermia on Neurologic Outcomes Among Patients With Severe Traumatic Brain Injury: The POLAR Randomized Clinical Trial

IMPORTANCE

After severe traumatic brain injury, induction of prophylactic hypothermia has been suggested to be neuroprotective and improve long-term neurologic outcomes.

OBJECTIVE

To determine the effectiveness of early prophylactic hypothermia compared with normothermic management of patients after severe traumatic brain injury.

DESIGN, SETTING, AND PARTICIPANTS

The Prophylactic Hypothermia Trial to Lessen Traumatic Brain Injury-Randomized Clinical Trial (POLAR-RCT) was a multicenter randomized trial in 6 countries that recruited 511 patients both out-of-hospital and in emergency departments after severe traumatic brain injury. The first patient was enrolled on December 5, 2010, and the last on November 10, 2017. The final date of follow-up was May 15, 2018.

INTERVENTIONS

There were 266 patients randomized to the prophylactic hypothermia group and 245 to normothermic management. Prophylactic hypothermia targeted the early induction of hypothermia (33°C-35°C) for at least 72 hours and up to 7 days if intracranial pressures were elevated, followed by gradual rewarming. Normothermia targeted 37°C, using surface-cooling wraps when required. Temperature was managed in both groups for 7 days. All other care was at the discretion of the treating physician.

MAIN OUTCOMES AND MEASURES

The primary outcome was favorable neurologic outcomes or independent living (Glasgow Outcome Scale-Extended score, 5-8 [scale range, 1-8]) obtained by blinded assessors 6 months after injury.

RESULTS

Among 511 patients who were randomized, 500 provided ongoing consent (mean age, 34.5 years [SD, 13.4]; 402 men [80.2%]) and 466 completed the primary outcome evaluation. Hypothermia was initiated rapidly after injury (median, 1.8 hours [IQR, 1.0-2.7 hours]) and rewarming occurred slowly (median, 22.5 hours [IQR, 16-27 hours]). Favorable outcomes (Glasgow Outcome Scale-Extended score, 5-8) at 6 months occurred in 117 patients (48.8%) in the hypothermia group and 111 (49.1%) in the normothermia group (risk difference, 0.4% [95% CI, -9.4% to 8.7%]; relative risk with hypothermia, 0.99 [95% CI, 0.82-1.19]; P = .94). In the hypothermia and normothermia groups, the rates of pneumonia were 55.0% vs 51.3%, respectively, and rates of increased intracranial bleeding were 18.1% vs 15.4%, respectively.

CONCLUSIONS AND RELEVANCE

Among patients with severe traumatic brain injury, early prophylactic hypothermia compared with normothermia did not improve neurologic outcomes at 6 months. These findings do not support the use of early prophylactic hypothermia for patients with severe traumatic brain injury.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00987688; Anzctr.org.au Identifier: ACTRN12609000764235.

Propofol Infusion Syndrome: Efficacy of a Prospective Screening Protocol

Propofol infusion syndrome (PIS) is a potentially lethal complication of propofol marked by rhabdomyolysis, metabolic acidosis, and cardiac arrhythmias or collapse. The objective of this study was to determine the effectiveness of a prospective screening protocol to prevent PIS. All trauma patients admitted who received propofol as a continuous infusion were prospectively screened from November 1, 2013 to December 31, 2015. Variables studied included demographics, injury severity, laboratory values, infusion rates, and mortality. Serum creatine phosphokinase (CPK) and lactate were drawn daily. Propofol was stopped for a positive screen defined as an increase in CPK to greater than 5000 IU/L or lactate greater than 4 mmol/L. Positive and negative cohorts were compared. Two hundred and twenty-five patients met the inclusion criteria and 12 patients (5.3%) had propofol stopped because of elevated CPK. No differences were identified in demographics, transfusions, injury severity, hospital length of stay, or propofol dose. The positive screened group had longer intensive care unit length of stay (20 vs 13 days; P = 0.002) and increased vent days (14.5 vs 10 days; P = 0.008). Max serum osmolality (334 vs 305 mosm/kg; P = 0.049) and max serum CPK (6782 vs 1058 IU/L; P < 0.0001) were higher in the positive cohort. No cases of PIS occurred, and mortality (16.7 vs 15.5%; P = 0.999) was not different between the cohorts. The screening protocol was effective in eliminating PIS. Serial CPK evaluations provided an effective screening tool and serum lactate can be dropped from screening.

Optimizing sedation in patients with acute brain injury

Daily interruption of sedative therapy and limitation of deep sedation have been shown in several randomized trials to reduce the duration of mechanical ventilation and hospital length of stay, and to improve the outcome of critically ill patients. However, patients with severe acute brain injury (ABI; including subjects with coma after traumatic brain injury, ischaemic/haemorrhagic stroke, cardiac arrest, status epilepticus) were excluded from these studies. Therefore, whether the new paradigm of minimal sedation can be translated to the neuro-ICU (NICU) is unclear. In patients with ABI, sedation has ‘general’ indications (control of anxiety, pain, discomfort, agitation, facilitation of mechanical ventilation) and ‘neuro-specific’ indications (reduction of cerebral metabolic demand, improved brain tolerance to ischaemia). Sedation also is an essential therapeutic component of intracranial pressure therapy, targeted temperature management and seizure control. Given the lack of large trials which have evaluated clinically relevant endpoints, sedative selection depends on the effect of each agent on cerebral and systemic haemodynamics. Titration and withdrawal of sedation in the NICU setting has to be balanced between the risk that interrupting sedation might exacerbate brain injury (e.g. intracranial pressure elevation) and the potential benefits of enhanced neurological function and reduced complications. In this review, we provide a concise summary of cerebral physiologic effects of sedatives and analgesics, the advantages/disadvantages of each agent, the comparative effects of standard sedatives (propofol and midazolam) and the emerging role of alternative drugs (ketamine). We suggest a pragmatic approach for the use of sedation-analgesia in the NICU, focusing on some practical aspects, including optimal titration and management of sedation withdrawal according to ABI severity.