Protein and glucose metabolism during isolated closed-head injury

Patients with isolated closed-head injuries are characterized by excessive nitrogen loss, hyperglycemia, and increased caloric demand. However, the relative contributions of specific metabolic events such as protein breakdown and synthesis or glucose production and utilization to the physiological changes prevalent during isolated closed-head injury remains unestablished. By use of isotopic dilutions of L-[1-13C]leucine and D-[3-3H]glucose, components of protein and glucose metabolism were examined in patients with isolated closed-head injury (n = 7). Normal overnight-fasted volunteers (n = 8) were also studied as a reference point for comparison. Despite prevailing hyperinsulinemia (29 +/- 5 microU/ml), head-injured patients had elevated plasma leucine concentrations (183 +/- 22 vs. 144 +/- 8 mumol/l), whole body proteolysis (331 +/- 44 vs. 150 +/- 7 mg.kg-1.h-1), protein synthesis (248 +/- 38 vs. 126 +/- 11 mg.kg-1.h-1), and amino acid oxidation (84 +/- 11 vs. 23 +/- 3 mg.kg-1.h-1). Therefore nitrogen loss normally associated with isolated closed-head injury is primarily due to an increase in the rate of whole body proteolysis, with a greater proportion of the resultant amino acids being oxidized for energy. Furthermore, head-injured patients were hyperglycemic (6.7 +/- 0.3 mumol/l) with increased rates of glucose turnover (an estimate of production and utilization) compared with the controls (4.0 +/- 0.7 vs. 2.5 +/- 0.2 mg.kg-1.min-1). Hence, these data suggest that head injury, even in the absence of peripheral trauma, induces a physiological state of accelerated metabolism associated with resistance to insulin action.

Automated evoked potential monitoring

We have developed a computer system for use in the operating room and intensive care unit for the automated acquisition and classification of flash evoked potentials. The project goals were to: (1) acquire evoked potentials without user intervention; (2) recognize, label, and trend important parameters; and (3) alarm if parameters deviate too far from normal. The system consists of a Nicolet Pathfinder, programmed for periodic flash visual evoked potential acquisition and a personal computer for analysis. Analysis software utilizes the C+ +language. The system has been tested on sixteen cases, determinations of specific waveforms were validated ex post facto by two experts. Three parameters in each of three channels were correctly recognized in more than 87% of all waveforms acquired. No signals at all were obtained in only 0.8% of all samples.

Neurosurgical intensive care unit organization and function: an American experience

This article describes the organization and function of a university-based neurosurgical intensive care unit. The unit's success has been based in part on its physical structure and in larger part on its organization. Patients are comanaged by a team of neurosurgeons and anesthesiologist intensive care specialists, who receive twice-weekly input from all other participating patient care specialists, including nurses, physical therapists, social workers, and others. This type of approach promotes teamwork and fosters mutual respect among the team. It also improves patient care and, frequently, outcome.

Nimodipine reduces the toxicity of intravenous bupivacaine in rats

We examined nimodipine modification of bupivacaine toxicity in anesthetized male rats. Three minutes after pretreatment, group 1 (n = 11), group 3 (n = 10), and their respective control groups (n = 11 and n = 9) received intravenous bupivacaine LD50 (median lethal dose). After pretreatment, group 2 (n = 10), group 4 (n = 8), and their respective control groups (n = 10 and n = 8) received intravenous bupivacaine LD90 (90% lethal dose). Pretreatment was 200 micrograms/kg intravenous nimodipine in groups 1 and 2 and 500 micrograms/kg in groups 3 and 4. Control animals were pretreated with intravenous saline solution. Data were analyzed by chi 2-analysis and analysis of variance. Survival increased after 200 micrograms/kg nimodipine (P less than 0.05). In group 1, 9 (81%) of 11 survived compared with control animals (4 [36%] of 11). In group 2, 8 (80%) of 10 survived compared with control animals (2 [20%] of 10). Survival was not increased after 500-micrograms/kg nimodipine pretreatment. In group 3, 2 (22%) of 9 survived compared with control animals (4 [40%] of 10). In group 4, 4 (50%) of 8 survived compared with control animals (2 [25%] of 8). We conclude that nimodipine pretreatment with 200 micrograms/kg protects against fatal toxicity from LD50 and LD90 bupivacaine, but 500 micrograms/kg does not.

Pulmonary artery catheter introducers: do the component parts affect flow rate?

Arrow sheath introducers are useful during massive transfusion as well as during catheter insertion. However, each component (sheath, side port, and obturator/catheter) probably progressively impedes maximum flow. This study quantitates these flow changes. Six configurations (C) were tested: (C1) sheath; (C2) sheath, side port; (C3) sheath, side port, obturator; (C4) C3 with 1.5-in obturator; (C5) C3 with 0.25-in obturator; (C6) no components. Flow was measured five times with each configuration and compared. Flows (mL/min) (mean +/- SE) were: (C1) 838.1 +/- 11.2, (C2) 283.4 +/- 9.2, (C3) 149.9 +/- 7.9, (C4) 176.0 +/- 14.0, (C5) 232.5 +/- 5.5, (C6) 1030.5 +/- 11.6. Flow decreased progressively with C2 and C3 (P less than 0.0001). C4 did not increase flow, but C5 did (P less than 0.0001). C5 flow was comparable to C2 but less than C1 (P less than 0.0001). C6 flow was larger than any other configuration (P less than 0.0001). Flow increases in C2 and C5 over C3 and C4 were modest (25%-50%) compared with C1 (250%). Therefore, we do not recommend removing or cutting the obturator to improve flow. During massive transfusion, we recommend removal of the side port until smaller flows suffice.

Somatosensory evoked potentials are unchanged by reflex sympathetic dystrophy and by stellate ganglion block

Median nerve somatosensory evoked potentials (SEPs) were monitored in patients with chronic pain before and after stellate ganglion blockade. A change caused by the syndrome or by the block would suggest that SEPs might be useful in the diagnosis and treatment of chronic pain. We observed 20 subjects. Group I (n = 10) had chronic pain not involving the upper extremity. Group II (n = 8) had reflex sympathetic dystrophy of the arm. All patients underwent unilateral stellate ganglion block using an anterior paratracheal approach. The SEPs were recorded by median nerve stimulation on the blocked (affected) side and unblocked (unaffected) side before and 30 min after the block. Recording sites were ipsilateral brachial plexus, the cervical spinal cord, and the contralateral sensory cortex. There were no between-group differences before or after the block. Paired analysis within each group showed that the SEPs were not different from baseline (unaffected side before block) at any time throughout the study. We conclude that since SEPs are not changed by the reflex sympathetic dystrophy or stellate ganglion block, they would not be useful in the evaluation of pain or in determining the effectiveness of sympathetic block. Both the pain and the block appear to involve alteration of conducting pathways separate from those monitored by median nerve SEPs.

Cervical osteotomy and manipulation in ankylosing spondylitis: successful general anesthesia after failed local anesthesia with sedation

Ankylosing spondylitis is a disease that may deform any portion of the spine. Local anesthesia is generally recommended when undertaking corrective procedures for this problem. We present a case where local anesthesia was deemed unsatisfactory. Prior tracheal intubation facilitated the use of general anesthesia.

Pseudocholinesterase activity in human cerebrospinal fluid

Pseudocholinesterase (PCHE) activity and dibucaine numbers (DN) in the cerebrospinal fluid (CSF) and plasma of 10 ASA physical status 1 and 2 patients were measured using a kinetic method. CSF had a mean PCHE activity of 0.018 +/- 0.013 unit/ml with a DN of 59 +/- 4. Whereas, PCHE activity and DN in the plasma were 0.960 +/- 0.12 units/ml and 84 +/- 3, respectively. We also measured PCHE activity and DN in the CSF and plasma of 4 patients in whom there was a recent history of intraventricular bleeding. These patients had a CSF PCHE activity of 0.340 +/- 0.07 units/ml (DN = 78 +/- 3) and a plasma PCHE activity of 0.950 +/- 0.10 units/ml (DN = 82 +/- 2). Our data show that there is a low activity of PCHE in CSF, 1/20-1/100th that of plasma. Our data also show that PCHE activity increased to 1/4 to 1/2 that of plasma in CSF of patients with bleeding into CSF.

Median nerve somatosensory evoked potentials as an indicator of ischemia in a case involving an aneurysm of the internal carotid artery

We present a case report demonstrating that somatosensory evoked potentials (SEPs) suggested ischemia when an internal carotid aneurysm ruptured during surgical clipping. SEPs were also recorded from the contralateral cortex and subcortical and peripheral sites and remained unchanged. The use of multiple bilateral recording sites for SEP recording simplified the interpretation of acute changes.

Effect of short-term smoking halt on carboxyhemoglobin levels and P50 values

Fifteen informed volunteers who smoked one to two packs of cigarettes per day were studied to measure changes in carboxyhemoglobin levels and P50 after smoking was stopped for 12 hr. Before smoking was stopped, carboxyhemoglobin levels (6.55 +/- 0.40%) were above normal, and the P50 (22.92 +/- 0.25 mm Hg) was significantly shifted to the left. After smoking was stopped for 12 hr there was a significant decrease in carboxyhemoglobin levels to 1.06 +/- 0.16% (P less than 0.001), and P50 shifted towards normal to 26.41 +/- 0.14 mm Hg (P less than 0.001). The authors conclude that within even as little as 12 hr after cessation of smoking, carboxyhemoglobin and P50 levels change towards normal values.