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Biomedical subjects

R M Chesnut

Publications and source records attributed to R M Chesnut.

46 records · Page 3Linked to original sources
PubMed1992

Extracranial complications of severe head injury.

In order to define the role of intracranial and extracranial complications in determining outcome from severe head injury, 734 patients from the Traumatic Coma Data Bank were analyzed. Nine classes of intracranial and 13 classes of extracranial complications occurring within the first 14 days after admission were analyzed, while controlling for age, admission Glasgow Coma Scale motor score, early hypoxia or hypotension, and severe extracranial trauma. Outcome for survivors was based on the last recorded Glasgow Outcome Scale score, obtained a median of 521 days after injury. Intracranial complications did not significantly alter outcome for the study group. Of the extracranial complications, pulmonary, cardiovascular, coagulation, and electrolyte disorders occurred most frequently at 2 to 4 days. Infections developed later, peaking at 5 to 11 days. Gastrointestinal, renal, and hepatic complications followed no specific time course. Electrolyte abnormalities were the most frequent occurrence (59% of patients) but did not alter outcome. Pulmonary infections (41%), shock (29%, systemic blood pressure < or = 90 mm Hg for 30 minutes or more), coagulopathy (19%), and septicemia (10%) were significant independent predictors of an unfavorable outcome. Backward-elimination, stepwise logistic regression modeling indicated that the estimated reduction of unfavorable outcome was 2.9% for the elimination of pneumonia, 3.1% for coagulation disturbances, 1.5% for septicemia, and 9.3% for shock. These data suggest that extracranial complications are highly influential in determining the outcome from severe head injury and that significant improvements in outcome in a sizeable proportion of patients could be accomplished by improving the ability to prevent or reverse pneumonia, hypotension, coagulopathy, and sepsis.

Adolescent↗
PubMed1992

Surgical management of cervical radiculopathy. Indication, techniques, and results.

Cervical radiculopathy can be surgically approached either posteriorly or anteriorly and the anterior approach has been described with or without fusion. The choice of approach and technique must be based upon anatomic, pathophysiologic, and biomechanical principles in addition to the familiarity of the surgeon with the procedures. The authors discuss the use of the posterior approach for lateral soft-disk disease because it minimizes disruption of soft and bony tissues and does not markedly disrupt the biomechanics of the cervical spine. The anterior approach is preferred for radiculopathy involving osteophytic hard-disk disease, and when properly and carefully performed, the addition of an interbody fusion holds significant advantages over diskectomy without fusion.

Cervical Vertebrae↗
PubMed1991

Management of head injury. Treatment of abnormal intracranial pressure.

Intracranial hypertension is recognized as a fundamental pathophysiologic process in brain injury. Although the exact pressure level defining intracranial hypertension remains to be firmly established, the majority of evidence available currently suggests that ICP should generally be treated when it exceeds 20 mm Hg. We suggest that lesions in the temporal lobe be treated at 15 mm Hg owing to the special relationship of this region to the brain stem. Along with the individual intracranial pressure reading, however, the course of the pressure over time and the status of the intracranial compliance as reflected in the ICP waveform must be considered when evaluating the intracranial dynamics. There is mounting evidence that patients with intracranial hypertension may comprise a heterogeneous group and that subgroups differ in their optimal treatment strategies. Although we cannot as yet identify such groups, factors such as age, CT diagnosis, responsiveness to hyperventilation, pressure-volume index, and ICP waveform are emerging as important differentiating factors. In particular, young patients with absent perimesencephalic cisterns and a tight brain on CT scan who manifest intracranial hypertension may comprise a group more suitable for treatment with hyperventilation and hypnotics than with osmotic agents. Although this is yet to be firmly established, currently it should be considered when such a patient responds poorly early in the course of conventional therapy for raised ICP. Treatment of intracranial hypertension remains rooted in the conventional therapeutic maneuvers. Maintenance of the basic homeostatic state of the patient is to be supplemented with head elevation, sedation, pharmacologic paralysis, hyperventilation, CSF drainage, and osmotic therapy as indicated. Outside of the special considerations discussed earlier, barbiturates should only be considered in patients with refractory intracranial hypertension without preexisting cardiovascular contraindications. Although several other agents have shown promise, currently the most exciting agent appears to be etomidate, which may prove quite useful. As ICP is better defined and understood, many significant and experimentally approachable questions are recognized. The basic mechanisms of raised ICP are slowly becoming elucidated. Clinical clues with which to subdivide patients with intracranial hypertension are being defined. New agents with efficacy in lowering raised ICP are appearing, and determination of their mechanisms of action may provide insight into the underlying disorder.

Brain Edema↗
PubMed1983

Actions of GABA in developing rabbit hippocampus: an in vitro study.

The development of neuronal responses to gamma-aminobutyric acid (GABA) was examined using intracellular recording techniques in area CA1 of rabbit hippocampal slices maintained in vitro. Microapplication of GABA (via pressure ejection) in stratum pyramidale in slices from mature rabbits (age 1 month) evoked a hyperpolarization of CA1 pyramidal neurons. The reversal potential (Erev) for this response was approximately -70 mV. In contrast, local application of GABA into stratum pyramidale in slices from immature rabbits (age 7-10 days) produced a depolarizing response with an Erev of approximately -54 mV. The relationship between these findings and the development of inhibitory synaptic activity in rabbit hippocampus is discussed.

Action Potentials↗
PubMed1976

Influence of thyrotropin releasing hormone (TRH) on drug-induced narcosis and hypothermia in rabbits.

Thyrotropin releasing hormone (TRH) administered via the intracerebroventricular (icv) route in doses ranging between 0.1 and 100 mug decreased the duration of pentobarbital-induced narcosis in rabbits. Antagonism of narcosis occurred whether TRH was administered before or after the barbiturate. TRH doses above 10 mug produced, in addition, behavioral excitation and hyperthermia. The antagonism of phenobarbital-induced narcosis was not as profound; animals were aroused only for a short period of time, after which the narcotized state returned. However, TRH exerted a prolonged antagonism or reversal of the phenobarbital-induced hypothermia. The central nervous system depression and analgesia produced by morphine were unaffected by TRH, but hypothermia and respiratory depression were reversed. TRH may represent an arousal factor in mammalian brain.

Animals↗