Thiopental-Induced Neutropenia in Two Patients with Severe Head Trauma

Immunomodulators in anesthesia

PURPOSE OF REVIEW

Anesthetics are known to have immunomodulatory effects. These can be detrimental, inducing immunosuppression and facilitating the development of opportunistic infections, especially when used at high doses, for prolonged periods, or in patients with preexisting immune deficiency; or beneficial, modulating the inflammatory response, particularly in critical illness and systemic hyperinflammatory states.

RECENT FINDINGS

Anesthetics can have microbicidal properties, and both anti- and pro-inflammatory effects. They can act directly on immune cells as well as modulate immunity through indirect pathways, acting on the neuroimmune stress response, and have recently been described to interact with the gut microbiota.

SUMMARY

Anesthesiologists should take into consideration the immunomodulatory properties of anesthetic agents in addition to their hemodynamic, neuroprotective, and other impacts. In future, patient stratification according to the perioperative assessment of serum biomarkers associated with postoperative complications may be used to guide anesthetic agent selection based on their immunomodulatory properties.

Neutrophil extracellular traps exacerbate neurological deficits after traumatic brain injury

Traumatic brain injury (TBI) is a major cause of mortality and morbidity. Preventative measures reduce injury incidence and/or severity, yet one-third of hospitalized patients with TBI die from secondary pathological processes that develop during supervised care. Neutrophils, which orchestrate innate immune responses, worsen TBI outcomes via undefined mechanisms. We hypothesized that formation of neutrophil extracellular traps (NETs), a purported mechanism of microbial trapping, exacerbates acute neurological injury after TBI. NET formation coincided with cerebral hypoperfusion and tissue hypoxia after experimental TBI, while elevated circulating NETs correlated with reduced serum deoxyribonuclease-1 (DNase-I) activity in patients with TBI. Functionally, Toll-like receptor 4 (TLR4) and the downstream kinase peptidylarginine deiminase 4 (PAD4) mediated NET formation and cerebrovascular dysfunction after TBI. Last, recombinant human DNase-I degraded NETs and improved neurological function. Thus, therapeutically targeting NETs may provide a mechanistically innovative approach to improve TBI outcomes without the associated risks of global neutrophil depletion.

Severe hypokalemia and rebound hyperkalemia during barbiturate coma in patients with severe traumatic brain injury

OBJECTIVES

To evaluate the incidence of severe potassium disturbances during barbiturate coma therapy in patients with severe traumatic brain injury (TBI), and the characteristics of these patients.

METHODS

The study comprised 37 patients with severe TBI who were treated for barbiturate coma between 2015 and 2017 in level 3 intensive care units of two hospitals.

RESULTS

No potassium disturbance occurred in 14 patients. Seventeen patients developed mild-moderate hypokalemia (2.6-3.5mEq/L), and 6 patients developed severe hypokalemia (<2.5mEq/L) following the induction of barbiturate therapy. The incidence of mild-to-severe barbiturate-induced hypokalemia was 62.2% and the rate of severe hypokalemia was 16.2%. The mean potassium supply per day during thiopentone therapy was statistically significantly different between patients with mild-to-moderate hypokalemic and those with severe hypokalemic (p<0.001). Four of 6 patients with severe hypokalemia developed rebound hyperkalemia exceeding 6mEq/L following the cessation of barbiturate infusion. The nadir potassium concentration was 1.5mEq/L and the highest value was 6.8mEq/L. The mean time to reach nadir potassium concentrations was 2.8 days. The mortality rate of the 6 patients was 66.7%. Of the 2 survivors of severe hypokalemia, the Glasgow Outcome Scale (GOS) on discharge and the extended GOS one year after the trauma were 5 and 8 respectively.

CONCLUSIONS

Severe hypokalemia refractory to medical treatment and rebound hyperkalemia is a serious adverse effect of thiopentone coma therapy in patients with severe TBI. Excessive and aggressive potassium replacement during the barbiturate-induced hypokalemia period must be avoided. Weaning barbiturate treatment over time may be advantageous in the management of severe serum potassium disturbances.

Decrease in white blood cell counts after thiopentone barbiturate therapy for refractory intracranial hypertension: A common complication

Background:

Leucopenia has been reported after induction of thiopentone barbiturate therapy for refractory intracranial hypertension. However, the incidence and characterisitics are not well described.

Aims:

We performed a retrospective review to describe the incidence and characteristics of leucopenia after induction of thiopentone barbiturate therapy.

Setting and Design:

Our centre is a national referral centre for neurotrauma and surgery in a tertiary medical institution.

Materials and Methods:

We performed a retrospective review of all patients who received thiopentone barbiturate therapy for refractory intracranial hypertension during an 18 month period from January 2004 to June 2005 in our neurosurgical intensive care unit.

Statistical Analysis Used:

Statistical analysis was performed using SPSS version 15.0. All data are reported as mean ± standard deviation or median (interquartile range). The Chi square test was used to analyze categorical data and student t test done for comparison of means. For paired data, the paired t-test was used.

Results:

Thirty eight (80.9%) out of 47 patients developed a decrease in white blood cell (WBC) count after induction of thiopentone barbiturate coma. The mean decrease in WBC from baseline to the nadir was 6.4 × 10⁹/L (P < 0.001) and occurred 57 (3-147) h after induction. The mean nadir WBC was 8.6 ± 3.6 × 10⁹/L. Three (6.4%) patients were leucopenic, with a WBC count of 2.8, 3.1, and 3.6 × 10⁹/L. None of them were neutropenic. We did not find an association between decrease in WBC count and clinical diagnosis of infection. We did not find any association between possible risk factors such as admission GCS, maximum ICP prior to induction of barbiturate coma, APACHE II score, total duration and dose of thiopentone given, and decrease in WBC count.

Conclusions:

Decrease in WBC count is common, while development of leucopenia is rare after thiopentone barbiturate coma. Regular monitoring of WBC counts is recommended.

Interaction of thiopental with esomeprazole in critically ill patients

INTRODUCTION

Thiopental is a thiobarbiturate given in the case of brain injuries to reduce intracranial pressure and to manage cerebral ischemia. A pharmacokinetic model has been described previously in critically ill patients with a different therapeutic strategy. New treatment options prompted us to investigate if drug-drug interactions occur. A new model is proposed describing the influence of concomitant administration of esomeprazole on the distribution of thiopental.

METHOD

The study population comprised 52 critically ill patients (body weight 47.1-114 kg) aged 18-78 years who had been admitted into the critical care unit for treatment of intracranial hypertension. A total mean dose of 282.8 ± 172.7 mg/kg was given in 96 ± 72 h. Pharmacokinetic analysis was performed by using a nonlinear mixed-effect population model.

RESULT

A one-compartment open model with first-order elimination identified two covariates, namely, body weight on clearance and volume of distribution, and the administration of esomeprazole on volume of distribution. The mean values (% relative standard error) for total clearance (CL) and for central volume of distribution (Vd) in patients with and without concomitant esomeprazole were 5.3 L/h (9.2 %) and 256.1 (6.4 %) and 153.2 l (19.2 %), respectively.

CONCLUSION

Based on these results, we conclude that concomitant administration of esomeprazole increases the volume of distribution and the half-live of thiopental. This drug-drug interaction should be considered when a target concentration has to be reached.

[Interaction brain-lungs]

The brain and the lungs interact early and rapidly when hit by a disease process. Often well tolerated by the healthy brain, an impaired respiratory function may deteriorate further a "sick" brain. Hypoxemia is a prognostic factor in the brain-injured patients. At the opposite, an acute brain damage early impacts the lung function. Local brain inflammation spreads rapidly to the lung. It initiates an immunological process weakening the lungs and increasing its susceptibility to infection and mechanical ventilation. Sometimes this process is preceded by a swelling lesion, known as neurogenic pulmonary oedema, resulting from an sympathetic overstimulation which usually follows an intense and brutal surge of intracranial pressure. The management of brain-injured patients has to be directed toward the protection of both the brain and lung. Neuronal preservation is crucial, because of the lack of regenerative potential in the brain, unlike the lung. A compromise must be obtained between the cerebral and pulmonary treatments although they may conflict in some situations.

[Sedation and analgesia for the brain-injured patient]

Sedation-analgesia occupies an essential place in the specific therapeutic arsenal of the brain-injured patients. The maintenance of the perfusion of the brain, its relaxation and its protection are the fundamental objectives whose finality is to avoid the extension of the lesions and to preserve the neuronal capital. Sedation is instituted when patients are severely agitated or present a deterioration of their state of consciousness (GCS< or =8). Under cover of mechanical ventilation, sedation is the first line treatment of intracranial hypertension, a common pathway of various acute brain diseases of traumatic, vascular or other origin. The use of the combination of hypnotic and opioids is the rule. The combined action of these two classes reinforces and improves their sedative effects. Midazolam is the 2 benzodiazepine of reference. Propofol is more and more frequently added to the combination of hypnotic and opioids. The "propofol infusion syndrome" is a severe limitation to its long term administration in particular among patients presenting a severe septic or inflammatory state. Propofol will be imperatively stopped in the event of metabolic acidosis, rhabdomyolysis, acute renal insufficiency, hyperkaliemia or increase in the blood triglyceride levels. The use of thiopental is restricted to the most severe cases. Its use as a monotherapy at high doses is abandoned to the profit of a co-administration with midazolam or even with the combination of midazolam and propofol. Thiopental overdose is very frequent in the event of associated hypothermia. Etomidate does not have its place apart from induction in fast sequence. The neuro-protective effects of ketamine require to be demonstrated in man before being recommended routinely. Withdrawal of sedation can be responsible for a state of agitation which can be controlled by neuroleptics.