Targeted Temperature Management in Brain Injured Patients

Targeted temperature management and PbtO2 in traumatic brain injury

Introduction

Targeted Temperature Management (TTM) to normothermia is widely used in traumatic brain injury (TBI). We investigated the effects to of TTM to normothermia patients with TBI (GCS≤12) monitored with multimodality monitoring, to better understand the physiological consequences of this intervention.

Research question

In TBI patients cooled to normothermia and in which brain oxygenation deteriorates, are there changes in physiological parameters which are pertinent to brain oxygenation?

Material and method

102 TBI patients with continuous recordings of intracranial pressure (ICP) and brain oxygen tension (PbtO2) were studied retrospectively. Non-continuous arterial carbon dioxide (PaCO2) and oxygen (PaO2) tensions, and core body temperature (Tc) were added. PaO2 and PaCO2 were also corrected for Tc. Transitions from elevated Tc to normothermia were identified in 39 patients. The 8 h pre and post the transition to normothermia were compared. Data is given as median [IQR] or mean (SD).

Results

Overall, normothermia reduced ICP (12 [9-18] -11 [8-17] mmHg, p < 0.009) and Tcore (38.3 [0.3]-36.9 [0.4] oC, p < 0.001), but not PbtO2 (23.3 [16.6]-24.4 [17.2-28.7] mmHg, NS). Normothermia was associated with a fall in PbtO2 in 18 patients (24.5 [9.3] -20.8 [7.6] mmHg). Only in those with a fall in PbtO2 with cooling did ICP (15 [10.8-18.5] -12 [7.8-17.3] mmHg, p = 0.002), and temperature corrected PaCO2 (5.3 [0.5]- 4.9 [0.8] kPa, p = 0.001) decrease.

Discussion and conclusion

A reduction in PbtO2 was only present in the subgroup of patients with a fall in temperature corrected PaCO2 with cooling. This suggests that even modest temperature changes could result in occult hyperventilation in some patients. pH stat correction of ventilation may be an important factor to consider in future TTM protocols.

Effects and mechanisms of extremely cold environment on body response after trauma

With the outbreak of the Ukrainian crisis, extremely cold environment warfare has once again become the focus of international attention. People exposed to extremely cold environments may suffer from cold damage, further aggravate trauma, trigger high disability and mortality rates, and even cause serious sequelae. To declare the effects and mechanisms of the extremely cold environment on the body after trauma, this paper reviews, firstly, physiological reaction of human body in an extremely cold environment. Then, the post-traumatic body response in an extremely cold environment was introduced, and finally, the sequelae of trauma in extremely cold environment was further summarized in the paper. The results indicated that extremely cold environment can cause a series of damage to the body, especially the body after trauma. The extremely cold factor is a double-edged sword, showing a favorable and unfavorable side in different aspects. Moreover, in addition to the trauma suffered by the body, the subsequent sequelae such as cognitive dysfunction, anxiety, depression and even post-traumatic stress disorder may also be induced. The paper summarizes the human body's physiological response in an extremely cold environment, and declares the effects and mechanisms of the extremely cold environment on the body after trauma, which may provide a theoretical basis for effectively improving the level of combat trauma treatment in extremely cold regions.

Pharmacological torpor prolongs rat survival in lethal normobaric hypoxia

Resistance to hypoxia is one of the most prominent features of natural hibernation and is expected to be present in the pharmacological torpor (PT) that simulates hibernation. We studied resistance to lethal hypoxia (3.5% oxygen content) in rats under PT. To initiate PT, we used the previously developed pharmacological composition (PC) which, after a single intravenous injection, can induce a daily decrease in Tb by 7 °C-8 °C at the environmental temperature of 22 °C-23 °C. Half-survival (median) time of rats in lethal hypoxia was found to increase from 5 ± 0.8 min in anesthetized control rats to 150 ± 12 min in rats injected with PC, which is a 30-fold increase. Behavioral tests after PT and hypoxia, including the traveling distance, the number of rearing and grooming episodes, revealed that animal responses are significantly restored within a week. It is assumed that the discovered unprecedented resistance of artificially torpid rats to lethal hypoxia may open up broad prospects for the therapeutic use of PT for preconditioning to various damaging factors, treatment of diseases, and extend the so-called "golden hour" for lifesaving interventions.

Temperature management in acute brain injury: A systematic review of clinical evidence

Temperature alterations in neurocritical care settings are common and have a striking effect on brain metabolism leading to or exacerbating neuronal injury. Hyperthermia worsens acute brain injury (ABI) patients outcome. However conclusive evidence linking control of temperature to improved outcome is still lacking. This review article report an update -results from clinical studies published between March 2006 and March 2020- on the relationship between hyperthermia or Target Temperature Management and functional outcome or mortality in ABI patients.

MATERIALS AND METHODS

A systematic search of articles in PubMed and EMBASE database was accomplished. Only complete studies, published in English in peer-reviewed journals were included.

RESULTS

A total of 63 articles into 5 subchapters are presented: acute ischemic stroke (17), subarachnoid hemorrhage (14), brain trauma (14), intracranial hemorrhage (8), and mixed acute brain injury (10). This evidence confirm and extend the negative impact of hyperthermia in ABI patients on worse functional outcome and higher mortality. In particular "early hyperthermia" in AIS patients seems to have a protective role have as promoting factor of clot lysis but no conclusive evidence is available. Normothermic TTM seems to have a positive effect on TBI patients in a reduced mortality rate compared to hypothermic TTM.

CONCLUSIONS

Hyperthermia in ABI patients is associated with worse functional outcome and higher mortality. The use of normothermic TTM has an established indication only in TBI; further studies are needed to define the role and the indications of normothermic TTM in ABI patients.

Hypothermic properties of dexmedetomidine provide neuroprotection in rats following cerebral ischemia-reperfusion injury

Dexmedetomidine (Dex) is a sedative and analgesic agent that is widely administered to patients admitted to the intensive care unit, and has been demonstrated to result in hypothermia. Many patients have been revealed to benefit from therapeutic hypothermia, which can mitigate cerebral ischemia/reperfusion (I/R) injury following successful cardiopulmonary resuscitation. However, studies investigating the efficacy of Dex in I/R treatment is lacking. The present study aimed to investigate the efficacy of Dex in mitigating neuronal damage, and to determine the possible mechanism of its effects in a rat model of cardiac arrest (CA). CA was induced in Sprague-Dawley rats by asphyxiation for 5 min. Following successful resuscitation, the surviving rats were randomly divided into two treatment groups; one group was intraperitoneally administered with Dex (D group), whereas the control group was treated with normal saline (N group). Critical parameters, including core temperature and blood pressure were monitored following return of spontaneous circulation (ROSC). Arterial blood samples were collected at 10 min after surgery (baseline) 30 and 120 min post-ROSC; and neurological deficit scores (NDS) of the rats were taken 12 or 24 h after ROSC prior to euthanasia. The hippocampal tissue was then removed for analysis by histology, electron microscopy and western blotting. Rats in the D group exhibited a lower core temperature and higher NDS scores compared with the N group (P<0.05). In addition, Dex injection resulted in reduced expression of apoptotic and autophagy-associated factors in the hippocampus (P<0.05). Dex treatment induced hypothermia and improved neurological function in rats after ROSC following resuscitation from CA by inhibiting neuronal apoptosis and reducing autophagy, which suggested that Dex may be a potential therapy option for patients with CA.

The neurointensive nursery: concept, development, and insights gained

PURPOSE OF REVIEW

With the advent of therapeutic hypothermia for treatment of hypoxic ischemic encephalopathy, and improvements in neuroimaging and bedside neuromonitoring, a new era of neonatal brain-focused care has emerged in recent years. We describe the development of the first neurointensive care nursery (NICN) as a model for comanagement of neonates with identified neurologic risk factors by a multidisciplinary team constituted of neurologists, neonatologists, specialized nurses, and others with the goal of optimizing management, preventing secondary injury and maximizing long-term outcomes.

RECENT FINDINGS

Optimizing brain metabolic environment and perfusion and preventing secondary brain injury are key to neurocritical care. This includes close management of temperature, blood pressure, oxygenation, carbon dioxide, and glucose levels. Early developmental interventions and involvement of physical and occupational therapy provide additional assessment information. Finally, long-term follow-up is essential for any neurocritical care program.

SUMMARY

The NICN model aims to optimize evidence-based care of infants at risk for neurologic injury. Results from ongoing hypothermia and neuroprotective trials are likely to yield additional treatments. New technologies, such as functional MRI, continuous neurophysiological assessment, and whole genomic approaches to rapid diagnosis may further enhance clinical protocols and neonatal precision medicine. Importantly, advances in neurocritical care improve our ability to provide comprehensive information when counseling families. Long-term follow-up data will determine if the NICN/Neuro-NICU provides enduring benefit to infants at risk for neurologic injury.