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Biomedical subjects

R M Chesnut

Publications and source records attributed to R M Chesnut.

At least 19 recordsLinked to original sources
PubMed2001

Lack of effect of induction of hypothermia after acute brain injury.

BACKGROUND: Induction of hypothermia in patients with brain injury was shown to improve outcomes in small clinical studies, but the results were not definitive. To study this issue, we conducted a multicenter trial comparing the effects of hypothermia with those of normothermia in patients with acute brain injury. METHODS: The study subjects were 392 patients 16 to 65 years of age with coma after sustaining closed head injuries who were randomly assigned to be treated with hypothermia (body temperature, 33 degrees C), which was initiated within 6 hours after injury and maintained for 48 hours by means of surface cooling, or normothermia. All patients otherwise received standard treatment. The primary outcome measure was functional status six months after the injury. RESULTS: The mean age of the patients and the type and severity of injury in the two treatment groups were similar. The mean (+/-SD) time from injury to randomization was 4.3+/-1.1 hours in the hypothermia group and 4.1+/-1.2 hours in the normothermia group, and the mean time from injury to the achievement of the target temperature of 33 degrees C in the hypothermia group was 8.4+/-3.0 hours. The outcome was poor (defined as severe disability, a vegetative state, or death) in 57 percent of the patients in both groups. Mortality was 28 percent in the hypothermia group and 27 percent in the normothermia group (P=0.79). The patients in the hypothermia group had more hospital days with complications than the patients in the normothermia group. Fewer patients in the hypothermia group had high intracranial pressure than in the normothermia group. CONCLUSIONS: Treatment with hypothermia, with the body temperature reaching 33 degrees C within eight hours after injury, is not effective in improving outcomes in patients with severe brain injury.

Acute Disease↗
PubMed2000

A bedside method for investigating the integrity and critical thresholds of cerebral pressure autoregulation in severe traumatic brain injury patients.

To avoid ischaemic secondary insults after severe head injury (SHI) it would be helpful to know the relationship between cerebral perfusion pressure (CPP) and intracranial pressure (ICP). Static cerebrovascular autoregulation (AR) was tested in 14 patients after SHI. Mean arterial pressure (MAP) was varied to detect changes in intracranial pressure (ICP) indicative of intact AR. Three types of responses were observed: (1) MAP elevation causes an increase in ICP; (2) MAP elevation has no or very little effect on ICP; (3) MAP elevation lowers ICP; Changes between types 1/2 and type 3 suggests AR breakpoints. Varying response types and breakpoints were observed between and within patients. Lower AR breakpoints were seen from 60 to 80 mmHg CPP, upper breakpoints were as high as 112. CPP monitoring achieves a twofold utility in targeted therapy: (1) defining the range of intact AR; and (2) lower AR breakpoint assessment to avoid secondary insults. Although the precise relationship between pAR breakpoints and the adequacy of cerebral perfusion to meet metabolic needs remains unclear, a technique such as described here is simple and has much to offer in targeting therapy toward specific pathophysiological processes in traumatic brain injury.

Adolescent↗
PubMed2000

Cervical spine clearance and neck extension during percutaneous tracheostomy in trauma patients.

INTRODUCTION: The lack of cervical spine clearance and inability to extend the neck are assumed to be relative contraindications for percutaneous tracheostomy. OBJECTIVE: To determine the necessity of cervical spine clearance and neck extension in trauma patients receiving percutaneous tracheostomy. DESIGN: Prospective analysis of case series from August 1, 1995 to August 31, 1998. SETTING: A university-based Level I trauma center. PATIENTS: A total of 88 consecutive trauma patients receiving percutaneous tracheostomy. Patients were divided into two groups based on the radiographic or clinical status of their cervical spine: cleared and noncleared. RESULTS: The overall success and complication rate were 99% (87/88) and 11% (10/88), respectively. There were no procedure-related deaths. The cleared group consisted of 60 patients; three patients in this group who had "bull" or "thick" necks did not have full neck extension during percutaneous tracheostomy. The noncleared group consisted of 28 patients, 13 of which had known cervical spine fractures; 27 noncleared patients were maintained in the neutral position (no extension) during percutaneous tracheostomy, whereas one patient with low suspicion of spinal injury was partially extended. Of the 13 patients with cervical spine fractures, six patients had been stabilized with a halo or operative fixation, and seven patients were stabilized with a cervical collar at the time of percutaneous tracheostomy. The success rate was 100% (60/60) for the cleared group compared with 96% (27/28) for the noncleared group (p > .05). The complication rate was 13% (8/60) for the cleared group compared with 7.1% (2/28) for the noncleared group (p > .05). We had a 100% success rate and no complications in the seven patients with cervical spine injury who were stabilized with a cervical collar. No patient had spinal cord injury caused by percutaneous tracheostomy. CONCLUSION: Percutaneous tracheostomy can be safely performed in trauma patients without cervical spine clearance and neck extension, including patients with stabilized cervical spine or spinal cord injury.

Adolescent↗
PubMed1999

Summary report: evidence for the effectiveness of rehabilitation for persons with traumatic brain injury.

We evaluated the evidence for effectiveness of rehabilitation methods throughout the phases of recovery from traumatic brain injury (TBI) in adults. MEDLINE, HealthSTAR, CINAHL, PsycINFO, and the Cochrane Library were searched, and a total of 3,098 abstracts were reviewed. The strongest studies were critically appraised and their data placed in evidence tables. Results showed that to determine the effectiveness of rehabilitation interventions for persons with TBI, a commitment must be made to population-based studies, strong controlled research design, standardization of measures, adequate statistical analysis, and specification of health outcomes of importance to persons with TBI and their families.

Adult↗
PubMed1999

Effect of cognitive rehabilitation on outcomes for persons with traumatic brain injury: A systematic review.

We evaluated evidence for the effectiveness of cognitive rehabilitation methods to improve outcomes for persons with traumatic brain injury (TBI). A search of MEDLINE, HealthSTAR, CINAHL, PsycINFO, and the Cochrane Library produced 600 potential references. Thirty-two studies met predetermined inclusion criteria and were abstracted; data from 24 were placed into evidence tables. Two randomized controlled trials and one observational study provided evidence that specific forms of cognitive rehabilitation reduce memory failures and anxiety, and improve self-concept and interpersonal relationships for persons with TBI. The durability and clinical relevance of these findings is not established. Future research utilizing control groups and multivariate analysis must incorporate subject variability and must include standard definitions of the intervention and relevant outcome measures that reflect health and function.

Brain Injuries↗
PubMed1999

Evidence of case management effect on traumatic-brain-injured adults in rehabilitation.

The purpose of this study was to evaluate the evidence for effectiveness of case management during recovery from traumatic brain injury (TBI) in adults. After an overview of TBI incidence, prevalence, and problems, and a brief explanation of case management, the study methods are described, the findings are discussed and recommendations are made for future research. Medline, HealthSTAR, CINAHL, PsychINFO, and the Cochrane Library databases were searched and 83 articles met the criteria for review. The strongest studies (n = 3) were critically appraised and their design features and data were placed in two evidence tables. Due to methodological limitations, there was neither clear evidence of effectiveness nor of ineffectiveness. For future research, we recommend controlled research designs, standardization of measures, adequate statistical analysis and specification of health outcomes of importance to persons with TBI and their families.

Adult↗
PubMed1998

Neurogenic hypotension in patients with severe head injuries.

OBJECTIVE: To examine the occurrence of hypotensive episodes in patients with severe traumatic brain injuries that are not of hypovolemic origin and to investigate possible neurogenic or iatrogenic causes of such episodes. METHODS: We reviewed Traumatic Coma Data Bank (TCDB) records of the 248 patients with early hypotension. We attempted to eliminate episodes related to hemorrhagic hypovolemia by excluding patients with (1) extracranial injuries of Abbreviated Injury Scale scores > 3 (n = 99, 40%); (2) postresuscitation hematocrit levels < 35% (n = 76, 30.6%); (3) hematocrit levels decreasing to < 35% during the first 24 hours after injury (n = 47, 19%); and (4) patients with conflicting data (n = 5, 2%). This left 21 patients (8.5%) without discernible extracranial causes for their hypotension. RESULTS: Of these 21 patients, 4 had no extracranial injuries and 4 had only a single injury with Abbreviated Injury Scale score = 1. Hypotensive episodes were not associated with terminal or unsalvageable status. Mortality was 43%. Of the multiple factors investigated, the only two that were strongly associated with these "unexplained" hypotensive episodes were the presence of a diffuse injury pattern on computed tomography (n = 15, 71%) and the early use of mannitol or furosemide (n = 16, 76%) (It was policy at TCDB centers that hypotensive patients not receive diuretics until they were resuscitated.) CONCLUSIONS: (1) Some episodes of severe traumatic brain injury-related hypotension may be of neurogenic origin. (2) The risk/benefit ratio of early diuretic use in patients with severe traumatic brain injuries may be too high to support liberal use. These data strongly support the need for a study involving prospective collection of data describing the early blood pressure courses in such patients.

Adolescent↗
PubMed1997

The management of severe traumatic brain injury.

An approach to the initial evaluation, resuscitation, and treatment of the patient with severe traumatic brain injury is presented in terms of the underlying physiology and literature support. The primary importance of rapid and complete systemic resuscitation in terms of the "ABCs" is stressed, with the goal of optimizing cerebral perfusion and preventing secondary insults to the injured brain. The integration of brain-specific treatments and diagnostic maneuvers into resuscitation protocols is discussed, including the role of mannitol and hyperventilation as well as the prioritization of CT imaging of the brain.

Brain Injuries↗
PubMed1996

Myogenic motor-evoked potential monitoring using partial neuromuscular blockade in surgery of the spine.

STUDY DESIGN: The authors analyzed motor-evoked potentials using transcranial electrical cortical stimulation during spinal surgery in 40 patients under conditions of partial neuromuscular blockade. OBJECTIVES: The results were used to investigate the utility of motor-evoked potential monitoring to prevent neurologic injury in spinal surgery. SUMMARY OF BACKGROUND DATA: Noninvasive transcranial electrical motor-evoked potentials are reportedly effective in predicting postoperative spinal cord deficits caused by intraoperative occurrences. However, the sensitivity and specificity of these predictions have not been assessed under conditions of partial neuromuscular blockade during a wide variety of surgical procedures. METHODS: Compound muscle action potentials were recorded at the tibialis anterior muscle while general anesthesia was maintained with nitrous oxide, etomidate, and sufentanil. Surgery was performed at all spinal levels for a variety of diagnoses. RESULTS: Reference motor-evoked potential amplitudes, measured after induction of partial neuromuscular blockade, ranged from 25 to 7562 microV (median, 600 microV). Variation in intraoperative motor-evoked potential amplitude ranged from signal loss to a 3440% increase. A decrease to less than 20% of the individual reference value for motor-evoked potential amplitude occurred at least once in nine patients (22.5%) but as not associated with postoperative motor deficits. Two patients who had loss of motor-evoked potential signal without recovery did have postoperative motor deficits. Motor-evoked potentials predicted postoperative motor improvement in six patients. An improvement threshold of 160% of the reference amplitude predicted postoperative motor improvement with 100% sensitivity and 81% specificity. CONCLUSIONS: The authors support the utility of recording transcranial electrical motor-evoked potentials in spinal surgery under partial neuromuscular blockade. Recovery of lost motor-evoked potentials was not associated with postoperative motor deficits, whereas non-recovery of lost motor-evoked potentials was.

Adolescent↗