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Biomedical subjects

A Schubert

Publications and source records attributed to A Schubert.

At least 91 records · Page 5Linked to original sources
PubMed1990

The effect of ketamine on human somatosensory evoked potentials and its modification by nitrous oxide.

The effect of ketamine alone and in combination with N2O (70% inspired) on median nerve somatosensory evoked potentials (SSEPs) was investigated in 16 neurologically normal patients undergoing elective abdominopelvic procedures. The anesthetic regimen consisted of ketamine (2 mg/kg iv bolus followed by continuous infusion at a rate of 30 micrograms.kg-1.min-1) [corrected], neuromuscular blockade (atracurium), and mechanical ventilation with 100% oxygen. SSEP recordings were obtained immediately preinduction and at 2, 5, 10, 15, 20, and 30 min postinduction. Thereafter, N2O was added with surgical incision and maintained for 15 min. At 5-min intervals, SSEP recordings were again taken during and after N2O. With minor exceptions, mean cortical and noncortical latencies as well as noncortical-evoked potential amplitude were unaffected by either ketamine or N2O. Ketamine induction increased cortical amplitude significantly with maximal increases occurring within 2-10 min. For example, at 5-min postinduction, mean N1-P1 amplitude increased from 2.58 +/- 1.05 (baseline) to 2.98 +/- 1.20 microV and P1-N2 amplitude increased from 2.12 +/- 1.50 (baseline) to 3.99 +/- 1.76 microV. Throughout the 30-min period after ketamine induction, mean P1-N2 amplitude increased generally by more (57-88%) than did mean N1-P1 amplitude (6-16%). N2O added to the background ketamine anesthetic produced a rapid and consistent reduction in both N1-P1 and P1-N2 amplitude. Thus, at 1 min after N2O, mean N1-P1 amplitude decreased from 2.74 +/- 1.11 to 1.64 +/- 0.63 microV, while P1-N2 amplitude decreased from 3.32 +/- 1.52 to 1.84 +/- 0.87 microV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

pH-adjustment of 2-chloroprocaine quickens the onset of epidural anaesthesia.

The effect of pH-adjustment of three per cent 2-chloroprocaine (2-CP, Nesacaine MPF) on the onset, duration, and spread of epidural analgesia and anaesthesia was studied in patients undergoing lower extremity surgery. Forty ASA physical status I and II patients were randomized to two groups. In a double-blinded fashion, patients in both groups received an epidural injection of 15 ml of local anaesthetic (LA) solution via a Tuohy needle at the L3-4 interspace. Local anaesthesia for Group I was prepared by adding 3 mEq NaHCO3 to 27 ml three per cent 2-CP and for Group II was prepared by adding 3 ml 0.9 per cent NaCl to 27 ml three per cent 2-CP. Both solutions contained epinephrine (1:200,000). The pH of commercially prepared Nesacaine MPF was 3.19 +/- 0.02. The pH of the solutions used for Group I and Group II patients were 7.32 +/- 0.01 and 3.27 +/- 0.02, respectively. Times to analgesia and anaesthesia at the L2 dermatome were significantly decreased in Group I patients by 2.5 and 6.6 minutes, respectively. Likewise, pH-adjustment accelerated the attainment of maximum level of block by 2.8 min. No statistical differences were found between groups in the maximum level of epidural block, or in time to 2-segment regression. No precipitation of LA was observed in pH-adjusted solutions of 2-CP after 24 hours. We recommend the use of pH-adjusted three per cent 2-CP (Nesacaine MPF) to accelerate the onset of epidural block.

Adult↗
PubMed1987

The effect of high-dose fentanyl on human median nerve somatosensory-evoked responses.

Median nerve somatosensory evoked responses (MnSSERs) were recorded in nine neurologically normal adult cardiac patients before and during the administration of high-dose fentanyl. MnSSERs were recorded prior to induction and at t = 20 min and t = 45 min postinduction. Fentanyl was administered as a slow bolus (53.2 +/- 9.1 micrograms X kg-1), followed by a continuous infusion at 10-20 micrograms X kg-1 X hr-1 (total dose 63.6 +/- 10.1 micrograms X kg-1). All MnSSER waveform components remained recordable and easily identifiable during anaesthesia. The effect of fentanyl was more pronounced on cortical waveform components, leaving subcortical components largely unaffected. There was a significant increase in the latency of the cortical MnSSER at t = 20 min, e.g., for the initial negative cortical wave, N1, the latency was 21.18 +/- 1.55 ms preinduction versus 22.18 +/- 1.42 ms at t = 20 min. There was also a significant decrease in the amplitude of the cortical response at t = 20 min, i.e., 2.04 +/- 1.30 microV preinduction versus 1.31 +/- 0.74 microV at t = 20 min. However, the degree of change was quite variable (range = 0-65 per cent). No further changes occurred at t = 45 min. The authors conclude that MnSSERs can be consistently and reliably monitored during high-dose fentanyl anaesthesia. However, fentanyl produces modest but significant changes in the MnSSER which should be taken into account lest they be misinterpreted as neurologic injury in evolution.

Aged↗
PubMed1987

Loss of intraoperative evoked responses during dorsal column surgery associated with isolated postoperative sensory deficit.

Two patients underwent surgery for the removal of dermoid tumors that involved the dorsal aspect of the spinal cord. Both patients were monitored with intraoperative posterior tibial nerve somatosensory evoked potentials (SSEPs). In each case, the surgical procedure was nearly complete when an abrupt and persistent loss of SSEPs occurred. Although minor recovery of waveforms was present by the end of the operation, the SSEP waveforms remained strikingly abnormal. Neither patient had a postoperative motor deficit, although both had evidence of dorsal column dysfunction. These observations suggest that, during dorsal column surgery, even dramatic SSEP loss may not be associated with motor pathway injury, but rather, may correlate better with postoperative dorsal column dysfunction. The possible implications for intraoperative monitoring of SSEPs during dorsal column surgical procedures are discussed.

Child↗
PubMed1987

The influence of stimulus presentation rate on the cortical amplitude and latency of intraoperative somatosensory-evoked potential recordings in patients with varying degrees of spinal cord injury.

Fourteen patients whose posterior tibial nerve somatosensory cortical-evoked potentials (SCEPs) were monitored for spinal surgery, underwent sequential recordings at different stimulus rates (6.1, 5.1, 4.1, 3.1, 2.1, and 1.1 Hz), after induction of anesthesia and patient positioning but before the incision was made. A markedly detrimental influence of higher (5.1 and 6.1 Hz), yet commonly used, stimulus rates on the amplitude of the evoked potential waveform was noticed. This tendency was most pronounced in patients with an antecedent spinal cord injury. In three patients with severe incomplete cord injuries, the amplitude of the cortical-evoked potential was sufficiently attenuated to preclude reliable intraoperative monitoring when stimulus rates of 5.1 Hz and greater were used. By contrast, evoked potentials could be monitored reliably in all patients when stimulus rates of 1.1 or 2.1 Hz were used. Six of seven patients (87%) whose evoked response amplitude showed a major reduction with higher stimulus frequencies had either a discrete sensory level or bilateral lower extremity weakness or both. Only two of seven patients (29%) whose evoked potential remained minimally affected by the stimulus rate had similar neurologic impairment. The authors conclude that, particularly in the setting of severe incomplete spinal cord injuries, the higher rates of stimulus presentation commonly used may result in failure to obtain waveforms that are adequate for intraoperative SCEP monitoring. The use of unconventionally low stimulus rates may greatly facilitate SCEP monitoring in such situations.

Adolescent↗
PubMed1987

Effect of the acute administration of high dose pentobarbital on human brain stem auditory and median nerve somatosensory evoked responses.

Brain stem auditory (BAERs) and median nerve somatosensory evoked responses (MnSSERs) were recorded from normal neural pathways during the induction of pentobarbital coma in six patients undergoing elective excision of complex arteriovenous malformations. Each patient received a 33-minute infusion of pentobarbital at a rate of 0.6 mg/kg (total dose, 19.8 mg/kg). This regimen resulted in burst suppression or isoelectricity of the electroencephalogram in all patients. Although statistically significant changes in latency and amplitude occurred, both BAERs and MnSSERs were readily recordable in all patients throughout the infusion. For the BAER, there were significant increases in the latencies of Waves III and V. However, these increases are sufficiently small that misinterpretation of these changes as an evolving neurological injury is unlikely, e.g., Wave V latency increased from 6.25 +/- 0.25 (SD) to 6.58 +/- 0.16 ms (P less than 0.006). For the MnSSER, changes of greater potential clinical relevance were observed. There were substantial increases in the latencies of the early components of the primary cortical response and in the central conduction time (e.g., CCT of 6.1 +/- 0.6 ms preinduction vs. 7.7 +/- 1.1 ms at t = 33 min, P less than 0.003), and the amplitude of the early cortical response (N20-P25) decreased by a mean of 45% (P less than 0.02). By contrast, subcortical components of the MnSSER (brachial plexus, upper cervical spine) were only minimally affected. We conclude that, in patients who are initially neurologically intact, BAERs and MnSSERs can be monitored effectively during pentobarbital coma and that the loss of these responses should not be ascribed to the effects of this drug alone. However, the interpretation of evoked response changes, particularly MnSSER changes, that occur during pentobarbital administration should take into account the dose-related changes in latency and amplitude that we have observed.

Adult↗
PubMed1987

Selenium content of a core group of foods based on a critical evaluation of published analytical data.

References published since 1960 that report analyses of selenium in foods were collected and evaluated according to criteria in five categories: number of samples, analytical method, sample handling, sampling plan, and analytical quality control. Data were grouped by food item and rated according to the criteria that had been developed specifically for evaluating the quality of selenium data. Ratings assigned to the data from each study yielded a Quality Index, indicating which data would be included in the calculation of the mean selenium value for each food item. The Quality Indexes for acceptable studies were summed to determine a Confidence Code, intended to indicate the relative degree of confidence the user can have in each mean selenium value. The selection of selenium core foods was based on their selenium concentration and frequency of consumption. Foods were ranked by multiplying selenium concentration by the amount consumed by the 36,255 individuals who provided 3-day dietary intake data in the U.S. Department of Agriculture's 1977-78 Nationwide Food Consumption Survey. Mean, minimum, and maximum selenium values, Confidence Codes, ranks, and references have been compiled for 114 food items. The five most highly ranked food aggregates (beef, white bread, pork, chicken, and eggs) provided half of the selenium accounted for in the diets of the survey respondents.

Diet↗
PubMed1986

[Life expectancy of diabetics].

The disease-specific life expectancy of diabetics is significant for the organisation of medical care. The investigations show that the disease-specific expectation of life of diabetics from the beginning of the disease is considerably more insignificant in comparison to the further life expectancy of the population in the younger and middle age groups. Only with increasing age of onset the life expectations of diabetics draw towards those of the population. Thus the lower life expectancy of the diabetics of younger age groups from the beginning of the disease now as ever may point to a higher risk in comparison to the disease population at the decline of life.

Aged↗
PubMed1986

The effect of acute hypocapnia on human median nerve somatosensory evoked responses.

This study was undertaken to define the effect of acute hypocapnia on intraoperatively recorded somatosensory evoked potentials (SSEPs). Median nerve SSEPs were studied in ten anesthetized neurologically normal adult patients undergoing elective nonneurologic surgery. End-tidal carbon dioxide tension (ETCO2) was allowed to stabilize for 15 min before SSEP recordings were obtained during normocapnia (N) (ETCO2 = 39.9 +/- 1.45 mm Hg), hypocapnia (H) (ETCO2 = 20.6 +/- 1.07 mm Hg), and after return to normocapnia (NR). Although a trend toward a reduction in the latencies of all SSEP components was evident, only the cervical (CII), and cortical (N1 and P1) latencies decreased significantly with H when compared to N. Mean latencies for CII, N1, and P1 (+/- SD) were, respectively, 14.80 +/- 1.14, 20.93 +/- 1.50, and 25.17 +/- 2.88 msec during N, and 14.50 +/- 1.13, 20.25 +/- 1.49, and 24.23 +/- 2.52 msec during H. On return to normocapnia, latencies were unchanged from N. Cortical latencies were affected to a greater extent than subcortical ones. Aside from a small but statistically significant increase in CII amplitude at H (2.05 +/- 0.55 microV vs 1.83 +/- 0.49 microV at N), SSEP amplitudes were unaffected by hypocapnia. The authors conclude that acute hypocapnia in neurologically normal patients results in a small reduction of SSEP latencies. The magnitude of the change is such that it is unlikely to interfere with recording or interpretation of intraoperative SSEPs.

Carbon Dioxide↗
PubMed1985

[Diabetes mellitus--age specific morbidity in the district of Newbrandenburg].

As a result of the investigations on the age-specific morbidity of diabetes mellitus in the county of Neubrandenburg is established that the risk of the disease greatly increases from the younger age-groups to the older ones. At old age the frequency of new diseases clearly decreases. It is probable that in genetically determined men on account of the risk factors, e.g. overweight, appearing more frequently with growing age diabetes becomes untimely manifest, so that they at first evoke the great increase of the age-specific frequency of new diseases. But then the risk-group of the population already fell ill as far as in the older age-groups the lower risk of a disease of the that group of population in dominating in which the diabetes genetically determines and finally becomes manifest. Also the age-specific amount and mortality rates are influenced by this. Whereas the age-specific mortality of the population of diabetics follows the risk of dying increasing at old age.

Adolescent↗
PubMed1985

A program designed to facilitate the repetitive acquisition, display, and disk storage of sensory evoked responses.

We present an algorithm that permits automated acquisition, display, and disk storage of single or dual channel sensory evoked potential waveforms using a Pathfinder II evoked response monitor. Once initiated, data acquisition and storage continue at user-specified intervals without additional user input. A cascade screen display provides trend monitoring. The file for data storage is established and searched using standard Pathfinder commands. The algorithm is written in MECOL, the Pathfinder specific programming language. This programming code imposed a number of limitations that had to be overcome to create a versatile and user friendly algorithm. During clinical use in our operating rooms, the program has been found effective and easy to use by both veteran and novice Pathfinder operators. The "hands-off" trend monitoring permitted by this algorithm has reduced the labor-intensive aspect of sensory evoked potential monitoring.

Evoked Potentials, Somatosensory↗
PubMed1985

Sterility of anesthetic multiple-dose vials after opening.

Despite the widespread use of multiple dose vials (MDV) for anesthetic medications, there is a paucity of data concerning the sterility of in-use MDV. The purpose of this study was to analyze the frequency of bacterial contamination of MDV used in current anesthesia practice. The authors collected weekly samples from 351 in-use MDV for seven consecutive weeks and cultured them using appropriate bacterial growth media. The vials contained drugs including neuromuscular blockers, anticholinergics, and an induction agent. They were sampled from locations designated for elective as well as emergency surgery. Six vial subgroups were studied with multiple samplings for 6-48 days. One-half of all opened vials remained in use after 4-9 days, while less than 5% remained after 6 weeks. No vial yielded bacteria. The authors conclude that the incidence of MDV contamination with live bacteria is low for the anesthetic medications studied. This appeared to be true even for vials with increasing duration of use and for vials from locations where emergency surgery commonly was performed.

1-Propanol↗
PubMed1985

Obesity in Europe.

The high prevalence of obesity in Europe is similar to that in other industrialized areas. Obesity and its related diseases, such as hypertension, hyperlipidemia, diabetes, and hyperuricemia, have become a major problem, particularly in terms of cost. Prospective studies in Scandinavia strongly suggest obesity and its related diseases lower life expectancy. Divergent results from the Seven Countries Study are critically discussed.

Adolescent↗