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BACKGROUND: Burnout can lead to health and psychologic problems and is apparently increasing in physicians and nurses. Previous studies have not evaluated all healthcare workers within a single work unit. This study evaluates the risk of burnout in all medical personnel in one perioperative unit. METHODS: We developed an online survey that included demographics, a modified version of the Maslach Burnout Inventory-Human Services Survey, and the Social Support and Personal Coping Survey. Survey constructs (e.g., depersonalization and health) and a global score were calculated. Larger construct and global values were associated with higher risk of burnout. These were separately regressed on role, age, and sex. The global score was then regressed on each of the survey constructs. RESULTS: Of the 145 responses, 46.2% were physicians (22.8% residents), 43.4% were nurses or nurse anesthetists, and 10.3% were other personnel. After adjusting for sex and age, residents scored higher than other physicians on the following (expected change [95% confidence interval]): global score (1.12 [0.43-1.82]), emotional exhaustion (1.54 [0.44-2.60]), and depersonalization (1.09 [0.23-1.95]). Compared with nonphysicians, residents were 1 U or more higher on these items (P < 0.05 in all cases). Residents had higher health (1.49 [0.48-2.50]) and workload (1.23 [0.07-2.40]) values compared with physicians. Better health, personal support, and work satisfaction scores were related to decreased global scores (P < 0.05). CONCLUSIONS: Physicians (particularly residents) had the largest global burnout scores, implying increased risk of burnout. Improving overall health, increasing personal support, and improving work satisfaction may decrease burnout among perioperative team members. [ABSTRACT FROM AUTHOR]

Background: The supraspinatus is most frequently involved in rotator cuff tears, a common orthopaedic condition. However, the architecture of this muscle has been described only for the superficial, anterior, and posterior regions., Purpose: To determine the muscle architecture of the deep supraspinatus., Study Design: Descriptive laboratory study., Methods: Muscle architecture measurements were collected from 25 cadaveric supraspinatus specimens (13 intact [without tendon tears], 3 with partial-thickness tears, 9 with full-thickness tears). The muscle was divided into deep, superficial anterior, and superficial posterior regions. Pennation angle, raw and normalized fiber length, and sarcomere length and number were compared using repeated-measures analyses of variance., Results: First, mean architecture measurements were compared between regions using only the intact specimens (n = 13). The deep region had a lower mean pennation angle (3.3° ± 1.0°) compared with the posterior region (11.0° ± 3.9°; P < .0001), which in turn had a significantly higher pennation angle compared with the anterior region (7.6 ± 2.6°; P = .0005). Normalized fiber lengths in the deep region were 21.1% ( P = .0052) and 34.5% ( P < .0001) shorter than the posterior and anterior normalized fiber lengths, respectively. Sarcomere lengths in the deep region were longer (3.4 ± 0.2 μm) compared with the posterior (3.1 ± 0.2 μm; P = .0012) and anterior (3.2 ± 0.2 μm; P = .0390) regions. Sarcomere numbers also decreased in the deep region by 21.2% ( P = .0056) and 34.2% ( P < .0001) compared with the posterior and anterior regions, respectively., Conclusion: The deep supraspinatus had significantly lower pennation angles, shorter fiber lengths, and fewer but longer sarcomeres in series compared with other subregions within the muscle. These structural differences suggest a functionally unique "submuscle" within the supraspinatus., Clinical Relevance: Understanding the architecture of the supraspinatus muscle can provide insight into muscle function in health and disease. Specifically, this deep submuscle may play a different role in rotator cuff function than the rest of the muscle., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Financial support was received from the Wu Tsai Human Performance Alliance and the Joe and Clara Tsai Foundation. J.G.L. has received education payments from ImpactOrtho and SportsTek Medical, consulting fees from Vericel, nonconsulting fees from Vericel, investment payments from Anika Therapeutics, honoraria from Vericel, and hospitality payments from Medtronic. A.S. has received education payments from Arthrex, ImpactOrtho, and SportsTek Medical; consulting fees from Arthrex; and nonconsulting fees from Arthrex and ImpactOrtho. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2024.)

The rabbit supraspinatus is a useful translational model for rotator cuff (RC) repair because it recapitulates muscle atrophy and fat accumulation observed in humans after a chronic tear (the "first hit"). However, a timeline of RC tissue response after repair, especially with regard to recent evidence of muscle degeneration and lack of regeneration, is currently unavailable. Thus, the purpose of this study was to characterize the progression of muscle and fat changes over time after the repair of a chronic RC tear in the rabbit model. Two rounds of experiments were conducted in 2017-2018 and 2019-2020 with N = 18 and 16 skeletally mature New Zealand White rabbits, respectively. Animals underwent left supraspinatus tenotomy with repair 8 weeks later. The unoperated right shoulder served as control. The rabbits were sacrificed at 1-, 2-, 4-, and 8-weeks post-repair for histological and biochemical analysis. Atrophy, measured by fiber cross-sectional area and muscle mass, was greatest around 2 weeks after repair. Active muscle degeneration peaked at the same time, involving 8% of slide areas. There was no significant regeneration at any timepoint. Fat accumulation and fibrosis were significantly increased across all time points compared to contralateral. Statement of Clinical Significance: These results demonstrate model reproducibility and a "second hit" phenomenon of repair-induced muscle atrophy and degeneration which partially recovers after a short time, while increased fat and fibrosis persist., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wu, Gibbons, Esparza, Vasquez-Bolanos, Hyman, Dorn, Singh, Lane, Fithian, Ruoss and Ward.)

Chronic rotator cuff tears can cause severe functional deficits. Addressing the chronic fatty and fibrotic muscle changes is of high clinical interest; however, the architectural and physiological consequences of chronic tear and repair are poorly characterized. We present a detailed architectural and physiological analysis of chronic tear and repair (both over 8 and 16 wk) compared with age-matched control rabbit supraspinatus (SSP) muscles. Using female New Zealand White Rabbits ( n = 30, n = 6/group) under 2% isoflurane anesthesia, the SSP was surgically isolated and maximum isometric force was measured at four to six muscle lengths. Architectural analysis was performed, and maximum isometric stress was computed. Whole muscle length-tension curves were generated using architectural measurements to compare experimental physiology to theoretical predictions. Architectural measures are consistent with persistent radial and longitudinal atrophy over time in tenotomy that fails to recover after repair. Maximum isometric force was significantly decreased after 16 wk tenotomy and not significantly improved after repair. Peak isometric force reported here are greater than prior reports of rabbit SSP force after tenotomy. Peak stress was not significantly different between groups and consistent with prior literature of SSP stress. Muscle strain during contraction was significantly decreased after 8 wk of tenotomy and repair, indicating effects of tear and repair on muscle function. The experimental length-tension data were overlaid with predicted curves for each experimental group (generated from structural data), exposing the altered structure-function relationship for tenotomy and repair over time. Data presented here contribute to understanding the physiological implications of disease and repair in the rotator cuff. NEW & NOTEWORTHY We utilize an established method to measure the length-tension relationship for the rabbit supraspinatus in normal, torn, and repaired muscles. We then perform architectural analysis to evaluate structural changes after tear and repair. Although peak isometric force is lower in the tear and repair groups, there are no differences in peak stresses across groups. These findings indicate persistent structural changes (both radial and longitudinal atrophy) and physiological deficiencies (decreased peak force and uncoupling structure-function relationship) after tenotomy that do not significantly recover after repair.

Rotator cuff (RC) tears are prevalent in the population above the age of 60. The disease progression leads to muscle atrophy, fibrosis, and fatty infiltration in the chronic state, which is not improved with intervention or surgical repair. This highlights the need to better understand the underlying dysfunction in muscle after RC tendon tear. Contemporary studies aimed at understanding muscle pathobiology after RC tear have considered transcriptional data in mice, rats and sheep models at 2-3 time points (1 to 16 weeks post injury). However, none of these studies observed a transition or resurgence of gene expression after the initial acute time points. In this study, we collected rabbit supraspinatus muscle tissue with high temporal resolution (1, 2, 4, 8, and 16 weeks) post-tenotomy ( n = 6/group), to determine if unique, time-dependent transcriptional changes occur. RNA sequencing and analyses were performed to identify a transcriptional timeline of RC muscle changes and related morphological sequelae. At 1-week post-tenotomy, the greatest number of differentially expressed genes was observed (1,069 up/873 down) which decreases through 2 (170/133), 4 (86/41), and 8 weeks (16/18), followed by a resurgence and transition of expression at 16 weeks (1,421/293), a behavior which previously has not been captured or reported. Broadly, 1-week post-tenotomy is an acute time point with expected immune system responses, catabolism, and changes in energy metabolism, which continues into 2 weeks with less intensity and greater contribution from mitochondrial effects. Expression shifts at 4 weeks post-tenotomy to fatty acid oxidation, lipolysis, and general upregulation of adipogenesis related genes. The effects of previous weeks' transcriptional dysfunction present themselves at 8 weeks post-tenotomy with enriched DNA damage binding, aggresome activity, extracellular matrix-receptor changes, and significant expression of genes known to induce apoptosis. At 16 weeks post-tenotomy, there is a range of enriched pathways including extracellular matrix constituent binding, mitophagy, neuronal activity, immune response, and more, highlighting the chaotic nature of this time point and possibility of a chronic classification. Transcriptional activity correlated significantly with histological changes and were enriched for biologically relevant pathways such as lipid metabolism. These data provide platform for understanding the biological mechanisms of chronic muscle degeneration after RC tears., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Vasquez-Bolanos, Gibbons, Ruoss, Wu, Vargas-Vila, Hyman, Esparza, Fithian, Lane, Singh, Nasamran, Fisch and Ward.)

Background: Physician burnout may be at 'epidemic' proportions due to factors associated with modern healthcare practice and technology. Practice attributes vary appreciably among subspecialists. Understanding burnout incidence and its associated factors could illuminate potential causes and interventions. We evaluated burnFout, mental and physical health, and social support and coping skills in acute and chronic pain physicians and pediatric and cardiac anesthesiologists., Methods: We administered the Maslach Burnout Inventory Human Services Survey (MBI-HSS), a two-item self-identified burnout measure, the Veterans RAND 12-item Health Survey and the Social Support and Personal Coping Survey to subspecialty society members practicing acute and chronic pain management, pediatric anesthesiology and cardiac anesthesiology. Multivariable regression analysis compared the groups, and adjusted burnout prevalence was compared with an all-physician and an employed general population sample., Results: Among 1303 participants (response rates 21.6%-35.6% among the subspecialty groups), 43.4% met established burnout criteria (range 30.0%-62.3%). Chronic pain physicians had significantly worse scores (unadjusted) than the other three groups of subspecialty anesthesiologists, the all-physician comparator group and the general population comparator group. Mental health inversely correlated with emotional exhaustion and depersonalization in all groups. Self-identified burnout correlated with the full MBI-HSS (R=0.54; positive predictive value of 0.939 (0.917, 0.955)). Physicians' scores for personal accomplishment were higher than population norms., Conclusions: This study provides data on burnout prevalence and associated demographic, health and social factors in subspecialist anesthesiologists. Chronic pain anesthesiologists had significantly greater burnout than the other groups. The self-identified burnout metric performed well and may be an attractive alternative to the full MBI-HSS., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

The rotator cuff (RC) muscles are crucial in moving and stabilizing the glenohumeral joint, and tears can be functionally devastating. Chronic fatty and fibrotic muscle changes, which are nonresponsive to surgical tendon repair, are a focus of contemporary research. The rabbit model recapitulates key biological features of human RC tears, but function and physiology are poorly characterized; limited force and stress data are inconsistent with literature norms in other mammalian species. Here, we present an improved method to assess the physiology of the rabbit supraspinatus muscle (SSP), and we report values for healthy SSP architecture and physiology. Using female New Zealand White Rabbits ( n = 6) under 2% isoflurane anesthesia, we surgically isolated the SSP and maximum isometric force measured at 4-6 muscle lengths. Architectural analysis was performed, and maximum isometric stress was computed. Whole muscle length-tension curves were generated using architectural measurements to compare experimental physiology to theoretical predictions. Maximum isometric force (80.87 ± 5.58 N) was dramatically greater than previous reports (11.06 and 16.1 N; P < 0.05). Architectural measurement of fiber length (34.25 ± 7.18 mm), muscle mass (9.9 ± 0.93 g), pennation angle (23.67 ± 8.32°), and PCSA (2.57 ± 0.20 cm 2 ) were consistent with prior literature. Isometric stress (30.5 ± 3.07 N/cm 2 ) was greater than previous reports of rabbit SSP (3.10 and 4.51 N/cm 2 ), but similar to mammalian skeletal muscles (15.7-30.13 N/cm 2 ). Previous studies underestimated peak force by ∼90%, which has profound implications for interpreting physiological changes as a function of disease state. The data that are presented here enable understanding the physiological implications of disease and repair in the RC of the rabbit. NEW & NOTEWORTHY We introduce an improved method to assess rabbit supraspinatus muscle physiology. Maximum isometric force measured for the rabbit supraspinatus was dramatically greater than previous reports in the literature. Consequently, the isometric contractile stress reported is almost 10 times greater than previous reports of rabbit supraspinatus, but similar to available literature of other mammalian skeletal muscle. We show that previous reports of peak supraspinatus isometric force were subphysiological by ∼90.

Purpose of Review: This review summarizes the history and scope of physician burnout, and explores recent advances in its understanding. With a particular focus on physicians who have completed their training, it also explores the present and future of interventions designed to alleviate the symptoms and sequelae of burnout., Recent Findings: Nearly 50 years since first described, burnout continues to remain a pervasive issue within anesthesia and medicine as a whole. Recent work has continued to outline risk factors and specialty-specific prevalence, and explore individual and institutional interventions to prevent and treat symptoms., Summary: Burnout continues to impact all who work in healthcare, at all levels of training. This review highlights recent advances in our understanding of the scope, causes, and management of burnout. In light of the current COVID-19 pandemic, we hope that the national and international focus on preventing and remediating burnout will continue to expand and strengthen., (© Springer Science+Business Media, LLC, part of Springer Nature 2020.)

Purpose: Describe prevalence of burnout in perianesthesia nurses, explore risks, mitigating factors., Design: Cross-sectional descriptive., Methods: Survey containing Maslach Burnout Inventory, Short Form-12, and Social Support and Personal Coping was emailed to American Society of PeriAnesthesia Nurses. Regression analysis examined relationships between burnout and health, social support, personal coping, substance use, and demographics., Findings: Of 2,837 respondents, 18% were currently and 35% were formerly burned out, with lower incidence in those >40 years. Currently burned out nurses had worse health and also perceived a lack of advancement opportunities and organizational investment in the individual. Lower burnout was associated with regular participation in physical (P < .001), creative (P = .004), or mindfulness hobbies (P < .001) and ease in discussing work problems with spouse or partner (P = .001)., Conclusions: Despite burnout nurses' empathy for their patients is maintained. Interests outside of work, personal and work support, healthy work environment, and regular physical activities can improve burnout., (Copyright © 2019 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.)

Background: Burnout affects all medical specialists, and concern about it has become common in today's health care environment. The gold standard of burnout measurement in health care professionals is the Maslach Burnout Inventory-Human Services Survey (MBI-HSS), which measures emotional exhaustion, depersonalization (DP), and personal accomplishment. Besides affecting work quality, burnout is thought to affect health problems, mental health issues, and substance use negatively, although confirmatory data are lacking. This study evaluates some of these effects., Methods: In 2011, the American Society of Anesthesiologists and the journal Anesthesiology cosponsored a webinar on burnout. As part of the webinar experience, we included access to a survey using MBI-HSS, 12-item Short Form Health Survey (SF-12), Social Support and Personal Coping (SSPC-14) survey, and substance use questions. Results were summarized using sample statistics, including mean, standard deviation, count, proportion, and 95% confidence intervals. Adjusted linear regression methods examined associations between burnout and substance use, SF-12, SSPC-14, and respondent demographics., Results: Two hundred twenty-one respondents began the survey, and 170 (76.9%) completed all questions. There were 266 registrants total (31 registrants for the live webinar and 235 for the archive event), yielding an 83% response rate. Among respondents providing job titles, 206 (98.6%) were physicians and 2 (0.96%) were registered nurses. The frequency of high-risk responses ranged from 26% to 59% across the 3 MBI-HSS categories, but only about 15% had unfavorable scores in all 3. Mean mental composite score of the SF-12 was 1 standard deviation below normative values and was significantly associated with all MBI-HSS components. With SSPC-14, respondents scored better in work satisfaction and professional support than in personal support and workload. Males scored worse on DP and personal accomplishment and, relative to attending physicians, residents scored worse on DP. There was no significant association between MBI-HSS and substance use., Conclusions: Many anesthesiologists exhibit some high-risk burnout characteristics, and these are associated with lower mental health scores. Personal and professional support were associated with less emotional exhaustion, but overall burnout scores were associated with work satisfaction and professional support. Respondents were generally economically satisfied but also felt less in control at work and that their job kept them from friends and family. The association between burnout and substance use may not be as strong as previously believed. Additional work, perhaps with other survey instruments, is needed to confirm our results.

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.

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.

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.

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.

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.

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.

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 (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.

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.

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.