10 Agosto 2001
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Br J Anaesth 2001 Aug;87(2):283-6
Department of Anaesthetics, Royal Infirmary, Edinburgh EH3 9YW, UKCorresponding author.
[Medline record in process]
We compared the time to reach two anaesthetic end-points during induction of anaesthesia with a potent inhalation agent (sevoflurane) and an i.v. agent (propofol). We used a method to ensure steady breathing during inhalation induction, and measured loss of tone in the outstretched arm and loss of response to a painful stimulus. Thirty-eight female patients (age 39 (9) yr, weight 65 (11) kg, and height 165 (8) cm) (mean (SD)) were randomly allocated to receive either propofol or sevoflurane. The predicted induction dose of propofol, estimated from age and weight for each patient, was given at a rate of 1% of the induction dose per second, to a possible maximum of 2.5 times the predicted induction dose. Sevoflurane was given with an inhaled concentration of 8%, which was anticipated to cause loss of arm tone within 90-120 s. After loss of consciousness, we applied a painful electrical stimulus to a finger at 15-s intervals and measured the time to loss of motor response. The median times and interquartile values for loss of arm tone were 105 (88-121) s for sevoflurane and 65 (58-80) s for propofol. This was equivalent to 0.65 of the ED(50) of propofol. The time to loss of response to pain was 226 (169-300) s for sevoflurane. The variances of these three measurements were not significantly different, indicating that these dose-response relationships were similar. In contrast, only 11 of the patients given propofol lost the response to pain after 2.5xED(50) had been given. These results support previous evidence of substantial differences between anaesthetic end-points, and show that this evidence can be obtained using a simple and rapid method. Br J Anaesth 2001; 87: 283-6
PMID: 11493503, UI: 21384815
Br J Anaesth 2001 Jul;87(1):73-87
Department of Anaesthesiology and Intensive Care, Orebro Medical Centre Hospital, S-701 85 Orebro, Sweden.
Publication Types:
PMID: 11460815, UI: 21353862
Br J Anaesth 2001 Jul;87(1):62-72
Department of Surgical Gastroenterology, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark.
PMID: 11460814, UI: 21353861
Br J Anaesth 2001 Jul;87(1):47-61
Acute Pain Management Unit, York District Hospital, York YO3 7HE, UK.
PMID: 11460813, UI: 21353860
N Engl J Med 2001 Jul 26;345(4):266-75
Department of Obstetrics and Gynecology, University of Texas Southwestern School of Medicine, Dallas, USA. lapskyboy@aol.com
PMID: 11474666, UI: 21342640
Pain 2001 Aug;93(2):198-200
PMID: 11486756, UI: 21377975
Pediatrics 2001 Aug;108(2):482-4
New York, NY 10016.
PMID: 11483821, UI: 21376743
Spine 2001 Aug 15;26(16):E367-72
Departments of.
STUDY DESIGN: A comparative study of lumbar paraspinal muscle reflexes during sudden upper limb loading in healthy control subjects and patients with sciatica. OBJECTIVES: To assess reflex activation of paraspinal muscles during sudden upper limb loading. SUMMARY OF BACKGROUND DATA: Sudden upper limb loading and upper limb voluntary movements cause reflex activation of trunk muscles. A short latency response of approximately 50 msec of lumbar muscles has been observed before, but the reflexes have not been studied in patients with sciatica. METHODS: The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG from 20 patients selected for an operation as a result of disc herniation-related chronic low back pain and 15 back-healthy controls. Pain, disability, and depression scores were recorded. RESULTS: Short latency response of paraspinal muscles for unexpected upper limb loading was similar in healthy controls and patients with sciatica in supported standing. During normal standing anticipation shortened the lumbar reflex latency in healthy controls but not among the patients. CONCLUSIONS: The results provide evidence for impaired feed-forward control of lumbar muscles in patients with sciatica.
PMID: 11493866, UI: 21385891
Spine 2001 Aug 15;26(16):E361-6
Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
STUDY DESIGN: Cross-sectional study of 25 male golfers with chronic low back pain and 16 healthy controls of similar age. OBJECTIVES: To assess the association between functional capacity of the back extensors and the quadriceps muscles. SUMMARY OF BACKGROUND DATA: Chronic low back pain has been shown to lead to changes in muscle activation patterns of the abdominals and the gluteus maximus. The effect of chronic low back pain on lower limb function has not been investigated. METHODS: Back extensor endurance was assessed by a Biering-Sorensen test; surface EMG was measured bilaterally on the erector spinae at T12 and L4-L5. Muscle inhibition in the quadriceps was assessed by applying an electrical twitch to the maximally contracted muscle. The associations between holding time, decrease in EMG median frequency (i.e., the slope of the regression line on median frequency vs. time), and muscle inhibition were compared for study participants with chronic low back pain and controls. RESULTS: Mean back extensor holding times were 88 +/- 30 seconds for study participants with chronic low back pain and 92 +/- 17 seconds for controls. Both groups showed bilaterally similar decreases in EMG median frequency at L4-L5 and T12; however, the slopes were significantly steeper at L4-L5 than T12. Study participants with chronic low back pain with poor back endurance had significantly higher muscle inhibition compared with study participants with chronic low back pain with good back endurance, whereas such an association was not evident in healthy controls. CONCLUSIONS: In golfers with chronic low back pain reduced back endurance was associated with significant inhibition of the knee extensors, indicating that this muscle group cannot be activated to a full extent. These findings suggest a possible association between back extensor fatigability and knee extensor dysfunction in male golfers with chronic low back pain.
PMID: 11493865, UI: 21385890
Spine 2001 Aug 15;26(16):1788-93
Department of General Medical Practice, University of Aarhus, Aarhus, Denmark.
STUDY DESIGN: A population-based cross-sectional and 5-year prospective questionnaire study. OBJECTIVE: To investigate self-reported physical workload as a risk factor for low back pain. SUMMARY OF BACKGROUND DATA: Both physical and psychosocial workplace factors are considered risk factors for low back pain. However, today no consensus has been reached regarding the exact role of these factors in the genesis of low back pain. METHODS: Questionnaire data were collected at baseline for 1397 (and after 5 years for 1163) men and women aged 31-50 years at baseline. Low back pain ("any low back pain within the past year," "low back pain </= 30 days in total during the past year," "low back pain > 30 days in total during the past year") was analyzed in relation to physical workload (sedentary, light physical, and heavy physical work) using logistic regression and controlling for age, gender, and social group. The proportions of workers changing between the workload groups over the 5-year period were analyzed in relation to low back pain status. RESULTS: At baseline no statistically significant differences in low back pain outcomes were found for workers exposed to sedentary, light physical, or heavy physical work. This was true for all age, gender, and social groups. At follow-up there was a statistically significant dose-response association between any low back pain and longstanding low back pain within the past year and increasing physical workload at baseline also after controlling for age, gender, and social group. Subjects with heavy physical workload at baseline changed statistically significantly more often to sedentary work if they experienced low back pain for more than 30 days out of the past year. CONCLUSIONS: Having a sedentary job might have a protective or neutral effect in relation to low back pain, whereas having a heavy physical job constitutes a significant risk factor. Because of migration between exposure groups (the "healthy-worker" effect), longitudinal studies are necessary for investigating the associations between physical workload and low back pain.
PMID: 11493851, UI: 21385876
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