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Biomedical subjects

M P Mehta

Publications and source records attributed to M P Mehta.

89 records · Page 5Linked to original sources
PubMed1988

Accelerated onset of non-depolarizing neuromuscular blocking drugs: pancuronium, atracurium and vecuronium. A comparison with succinylcholine.

The time of onset and degree of neuromuscular blockade (NMB) in 80 anaesthetized patients, following either a single bolus injection of pancuronium 0.95 mg kg-1, atracurium 0.53 mg kg-1 or vecuronium 0.07 mg kg-1, or divided doses of pancuronium 0.15 mg kg-1, atracurium 0.07 mg kg-1 or vecuronium 0.01 mg kg-1 administered 3 min or 5 min before the second dose of pancuronium 0.08 mg kg-1, atracurium 0.46 mg kg-1 or vecuronium 0.06 mg kg-1, were determined and compared to the same parameters measured following succinylcholine administration (1 mg kg-1). The time to maximum NMB (100%) following the administration of succinylcholine was 58.1 +/- 5.3 s, whereas the time to maximum NMB (100%) following a single bolus injection of either pancuronium, atracurium or vecuronium was 130.6 +/- 22.2, 93.0 +/- 6.4, 127.5 +/- 13.0 s, respectively. These values for time to maximum NMB are significantly longer than the time required for succinylcholine to achieve maximal blockade. The time to attain maximum NMB following divided doses of pancuronium, atracurium or vecuronium separated by 3 min decreased significantly to 77.9 +/- 4.3, 77.5 +/- 7.6, 89.0 +/- 8.6 s, respectively. However, when the two doses of drug were separated by 5 min, only small, non-significant further decreases occurred in the time required to achieve maximum blockade. Although the time to maximum NMB following divided doses of pancuronium, atracurium or vecuronium is significantly longer than that for succinylcholine, divided dosing significantly decreases the time required to reach maximal NMB.

Adolescent↗
PubMed1987

Evaluation of the mutagenic potential of enflurane and isoflurane by sister chromatid exchange.

Chinese hamster lung cells were exposed to varying doses of enflurane and isoflurane mixed with oxygen, 5% carbon dioxide and nitrogen. Anesthetic concentrations varied between 0.5% and 4.0%. Controls were exposed to room air and 5% carbon dioxide. Following culturing and preparation, the number of sister chromatid exchanges were counted for each concentration. No significant difference occurred between the control and any of the drug exposed cultures. There was no correlation in the number of exchanges with the varying drug concentrations. Enflurane and isoflurane do not appear to be mutagenic under these conditions.

Animals↗
PubMed1985

Facilitation of rapid endotracheal intubations with divided doses of nondepolarizing neuromuscular blocking drugs.

The authors sought to determine whether prior administration of a small, subparalyzing dose of nondepolarizing muscle relaxant would shorten the onset time of an intubating dose of muscle relaxant. Initially, in 60 anesthetized patients, twitch response of adductor pollicis to ulnar nerve stimulation was studied after a small dose of pancuronium 0.015 mg . kg-1, metocurine 0.03 mg . kg-1, or d-tubocurarine 0.04 mg . kg-1, followed 3 min later by pancuronium 0.08 mg . kg-1 or atracurium 0.4 mg . kg-1 administered iv. After 60 s, the minimum neuromuscular block, in all patients was 79.0 +/- 5.0%. A 95% depression or twitch tension occurred between 59.1 +/- 5.3 and 86.1 +/- 5.9 s. In another 60 patients, intubating conditions under similar regimen were studied, except the small dose of muscle relaxant was given immediately prior to induction of anesthesia. At the end of 60 s, good to excellent intubating conditions were present in 100% of the patients following the second dose of pancuronium and in 83% of the patients following atracurium. In 17% of the patients, after atracurium intubating conditions were fair. When nondepolarizing neuromuscular blocking drugs are administered in divided doses, neuromuscular blockade adequate for endotracheal intubation is achieved in less than 90 s. This facilitates rapid endotracheal intubation in a time comparable to using succinylcholine, without undesirable effects of the depolarizing neuromuscular blocking drugs.

Adolescent↗
PubMed1985

Etomidate anesthesia inhibits the cortisol response to surgical stress.

Plasma cortisol was measured in 18 patients undergoing gynecological procedures under etomidate or methohexital and nitrous oxide anesthesia. Plasma ACTH was also measured in three patients in each group. The mean plasma cortisol concentration before anesthesia was comparable in both groups. Plasma cortisol increased in patients anesthetized with methohexital, while none of the patients anesthetized with etomidate had an increase in plasma cortisol. The increase in plasma ACTH was equivalent in the two groups. Therefore, etomidate is a potent inhibitor of the adrenal response to surgery. The absence of clinical consequences associated with the blunted response suggests that a major increase in adrenal hormone production may not be necessary during surgery.

Adrenal Cortex↗
PubMed1985

Anesthesia and neuromuscular diseases.

This presentation presents a short review of some disease entities affecting the nuromuscular system. Most of these diseases are rare, but many have a direct implication for anesthetic management and the anesthesiologist should be aware of them and the interaction of the patient's disease and the physician's drugs.

Anesthesia, General↗
PubMed1983

Cerebrospinal fluid pressure in normal obese subjects and patients with pseudotumor cerebri.

Cerebrospinal fluid (CSF) pressure was measured in four groups of patients: 116 with acute pseudotumor cerebri, 18 with chronic pseudotumor cerebri, 41 obese and 15 nonobese normal patients undergoing spinal anesthesia. Spinal fluid pressure between 200 and 250 mm H2O was found in members of each group. This suggests that when elevated CSF pressure is suspected, confirmation requires values greater than 250 mm H2O. The CSF pressure and degree of obesity could not be correlated in any meaningful way. There was no significant statistical difference between the mean CSF pressures obtained in the obese and nonobese normal populations.

Female↗
PubMedDate not supplied

Localized 2D J-resolved 1H MR spectroscopy of human brain tumors in vivo.

Application of two-dimensional (2D) J-resolved MR spectroscopy, fully localized in three dimensions to monitor the metabolites in human brain tumors in vivo on a whole body MR scanner is presented. A modified PRESS sequence with [90 degrees - 180 degrees - t1/2 - 180 degrees - t1/ 2-acquisition] was used for voxel localization (2D J point-resolved spectroscopy [PRESS]); chemical shift selective (CHESS) sequence was used for suppression of water. The incremental delay (t1/2) added to the intervals before and after the last slice-selective 180 degrees RF pulse allowed the monitoring of the J-evolution in a localized 2D NMR spectrum. The addition of the second frequency dimension in 2D J-resolved spectroscopy to encode the indirect spin-spin coupling allowed the visualization of lactate peaks not observed in the 1D MR spectrum because of severe overlap with lipid peaks. 2D spectra of a two-layer phantom with 100 mM alanine and corn oil and also from three patients with tumors are presented here. The 2D spectra show that the J-coupled lactate peaks could be separated even when the lipids peaks severely overlap.

Adult↗
PubMedDate not supplied

Psychological consequences of surgery.

The purpose of the present study was to assess changes in psychological distress and memory complaint following a wide variety of surgeries. In addition, variables reflecting type of surgery, demographic characteristics, history of mental illness, and health factors were evaluated as predictors of postoperative psychological distress and memory complaint. Using the Brief Symptom Inventory (BSI), it was found that 10.9% of patients had high levels of psychological distress the day before surgery compared to 13.9% of patients three months after surgery. Complaints of memory disturbance also increased significantly. Only the anxiety subscale of the BSI showed a significant decrease at three months postsurgery. Hierarchical multiple regression revealed that younger age, lower social status, being male, having a history of mental illness, higher presurgery BSI, and poorer postsurgery health were significant predictors of postsurgery psychological distress. The results of the study suggest that, although patients become less anxious after surgery, other forms of emotional distress increase, perhaps due to factors such as slower than anticipated recovery. Results also suggest that medical factors may play an indirect rather than a direct role in psychological consequences of surgery.

Adult↗
PubMedDate not supplied

The physical, biologic, and clinical basis of radiosurgery.

Since Leksell's description of the concept of radiosurgery in 1951, probably more than 20,000 patients worldwide have been treated with this technique. Initially designed as a tool for functional neurostereotaxis, it has found widespread applicability for conditions as diverse as vascular malformations, benign tumors such as acoustic neuroma, meningioma, pituitary adenoma, and also malignant tumors such as brain metastases and malignant glioma. From rudimentary knowledge of the ability to produce focal necrotic lesions, the biologic understanding of the process of single-fraction, small-volume, high-dose brain radiation has evolved into a multicompartmental model, with reasonable appreciation of the dose, volume, and time factors involved. With the explosion of technology on several fronts in the 1980s and 1990s, a multitude of devices for radiosurgery, ranging from cyclotron-generated particle beams to multisource cobalt-60 units to an immense variety of modified linear accelerators has become available. A parallel explosion of technology in the fields of imaging and computing will ensure that this is just the beginning; already, technologies for automated image segmentation and target identification, long the physician's monopoly, are around the corner; image fusion now allows simultaneous visualization of target and normal tissue anatomy, physiology, and other exciting possibilities such as chemical composition and vascular characteristics. Advances in physics and robotics have led to development of prototypical machines that will blur the distinction between radiosurgery and conformal radiotherapy. Already, several "first generation" devices to free stereotaxis from its fixation to frames are available. Substantial enthusiasm among clinicians has ensured that, unlike many fleetingly and momentarily exciting technologies of the last 2 decades, radiosurgery has made and will continue to make a strong commitment for clinical efficacy, safety, and cost-effectiveness through the process of thorough multiinstitutional clinical trials, as opposed to seeking validation from anecdotal experiences. In this regard, the Radiation Therapy Oncology Group (RTOG) and the Gamma Knife User's Group (GKUG) are to be commended; if the plethora of radiosurgery-related publications is evidence of scientific interest, the field will likely continue to expand. In the future, issues pertaining to appropriate regulatory review, patient selection, quality assurance, and training will need to be addressed. Major clinical and biological studies still need to be undertaken.

Adenoma↗