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Biomedical subjects

S Ramamurthy

Publications and source records attributed to S Ramamurthy.

At least 55 records · Page 3Linked to original sources
PubMed1989

Normative model for cold pressor test.

The cold pressor test elicits an emotional/motivational pain experience from the immersion of a limb in cold water. It has been widely used to evaluate (experimental and chronic) pain. However, normative models for quantification and comparison for pain tolerance have not previously been established. This study developed a normative mathematical model for pain tolerance using the cold pressor test with over 600 subjects. Norms for age, sex, and ethnic group were calculated. In addition, chronic pain patients were compared with pain-free patients to determine normative differences in response. The results indicate that at any given age Anglo-Saxon males have the longest tolerance time followed by non-Anglo-Saxon males, Anglo-Saxon females, and finally non-Anglo-Saxon females. There is a consistent decrease in tolerance time as the male age increases and minimal change in tolerance time as the female age increases. Chronic pain patients exhibited the same type of pain response pattern as healthy volunteers when corrected for age, sex, and ethnocultural subgroup.

Adolescent↗
PubMed1989

Diagnostic epidural opioid technique.

Diagnostic epidural blocks were performed on 27 chronic pain patients sequentially using saline, fentanyl, and lidocaine solution. The patients were divided into one of four groups based on their response to the epidural solutions: placebo response group--pain relief with placebo solutions; fentanyl response group--pain relief with epidural fentanyl; lidocaine response group (LRG)--pain relief with lidocaine but not fentanyl; and no response group--no pain relief with any of the solutions used. The four groups were compared on the basis of age, sex, site of pain, duration of pain, narcotic use, pain assessment index, and workmen's compensation claims. The comparisons resulted in the conclusion that LRG patients had a much longer average duration of pain than the other groups. On the basis of the information gathered, it was theorized that, despite their response to epidural lidocaine, LRG patients may actually be a group of operant pain patients. Their failure to receive analgesia from epidural fentanyl may be a learned response such that they associate any sensory input from the affected area as painful. If follow-up studies support these findings, then the diagnostic opioid technique may be a more sensitive tool in diagnosing chronic pain.

Adult↗
PubMed1989

Studies of the Modified Somatic Perceptions Questionnaire (MSPQ) in patients with back pain. Psychometric and predictive properties.

The Modified Somatic Perceptions Questionnaire (MSPQ) was designed to measure heightened somatic awareness among patients with chronic pain. It was hoped that this questionnaire would help predict therapeutic responses for back pain patients. The reliability, validity, and predictive characteristics of this scale were tested among 97 patients with chronic low-back pain enrolled in a clinical trial of transcutaneous nerve stimulation and stretching exercises. Internal consistency was good (alpha = 0.78), and correlations with the Zung depression scale and certain MMPI scales were significant. Correlations with a baseline functional scale (the Sickness Impact Profile) were stronger than those with the MMPI. Unfortunately, the MSPQ did not correlate with functional outcomes, and was only weakly associated with pain outcomes. Thus, the MSPQ appears to be reliable and valid, but the somatic perceptions it measures may have little relation to patient outcomes.

Awareness↗
PubMed1989

Subclavian perivascular block: influence of location of paresthesia.

Subclavian perivascular block of the brachial plexus was used in 156 adult patients undergoing orthopedic hand and forearm surgery. The location of the elicited paresthesia prior to deposition of 30 ml of a solution containing 1% mepivacaine, 0.2% tetracaine and 1.200,000 epinephrine was recorded. Twenty minutes later the quality of the block in the distribution of the superior, middle and inferior trunks of the brachial plexus was evaluated. Anesthesia in each of the three trunks was compared with the three sites where the paresthesia was elicited (superior, middle, or inferior trunk). A middle trunk paresthesia was the most successful in producing surgical anesthesia of all three trunks. A superior trunk paresthesia was the paresthesia most often elicited. It resulted in a significantly lower incidence of inferior trunk anesthesia than did a middle or inferior trunk paresthesia. Complications included arterial puncture (25.6%), Horner's syndrome (64.1%), and recurrent laryngeal nerve block (1.3%), with no instances of symptomatic phrenic block or symptomatic pneumothorax.

Adult↗
PubMed1989

The premotor potential.

A small waveform precedes the compound muscle action potential evoked from the thenar eminence with median nerve stimulation with high amplifier gains. This potential is believed to emanate from fibers destined to innervate the volar aspect of the first digit. It has been suggested recently that the source of the premotor potential is the palmar cutaneous branch of the median nerve. In this study, the palmar cutaneous branch of the median nerve was blocked at the wrist. A localized zone of anesthesia was observed over the proximal midpalm, not the thenar eminence, and the premotor response remained unchanged as did a midpalmar potential. The median nerve was then blocked at the base of the thenar eminence; only then did the premotor potential disappear. The palmar cutaneous branch of the median nerve innervates only a small portion of the medial aspect of the thenar eminence and does not produce the thenar premotor potential. Additionally, because of the close proximity of the main median nerve to its palmar cutaneous branch, volume conduction of stimuli and responses precludes an electrophysiologic technique which exclusively localizes the palmar cutaneous branch of the median nerve.

Action Potentials↗
PubMed1989

Reflex sympathetic dystrophy of the knee. Treatment using continuous epidural anesthesia.

We retrospectively reviewed the cases of fourteen patients who had reflex sympathetic dystrophy of the knee. All fourteen were hospitalized, and epidural block anesthesia was instituted with an indwelling catheter for an average of four days, during which continuous passive motion, manipulation (as necessary), stimulation of muscles, and alternating hot and cold soaks were used. The average length of follow-up was thirty-two months. Eleven patients had complete resolution of the symptoms, two had sufficient intermittent aching with changes in the weather to need medication, and one had no relief. The diagnosis was confirmed if the symptoms were relieved by a lumbar sympathetic block. Pain that was out of proportion to the severity of the injury was the most consistent finding, being present in all fourteen patients. However, variation in clinical severity is characteristic of the syndrome. Eleven of the fourteen patients had had a previous patellar operation. After the onset of the symptoms, nine patients had two or more arthroscopic examinations, without notable findings. All fourteen patients had had extensive physical therapy and medical treatment before the epidural block was performed.

Adult↗
PubMed1988

Prognostic variability among chronic pain patients: implications for study design, interpretation, and reporting.

Chronic pain patients share many characteristics, but there is important prognostic variability among them. By selecting for certain characteristics, different recruitment methods and entry criteria for clinical or research programs may influence the likelihood of success regardless of treatment efficacy. This was demonstrated when subjects (n = 55) were recruited through lay publicity for a clinical trial of therapy for chronic back pain. In comparison to routine pain clinic patients (n=61), subjects in the clinical trial were better educated, were more often employed, had more favorable personality profiles, and were less likely to have had surgery or narcotic use (all p less than 0.004). Pain relief was significantly better for clinical trial subjects, apparently due to baseline prognostic differences rather than uniquely efficacious therapy. We conclude that chronic pain patients vary in prognostically important ways; that recruitment methods and criteria strongly influence these characteristics; and that greater attention to these details is needed when interpreting and reporting clinical research.

Adult↗
PubMed1986

Analgesic effectiveness of D-phenylalanine in chronic pain patients.

Enkephalins are a biochemical pathway for endogenous analgesia. A number of compounds inhibit degradation of enkephalins within the body. One of these compounds, D-phenylalanine (DPA), has been shown to increase the pain threshold in animals. It is hypothesized that this naloxone reversible analgesia is induced by DPA blockage of enkephalin degradation by the enzyme carboxypeptidase A. Preliminary studies of chronic pain patients have shown a response rate to DPA from 32% to 75%. This study was a double-blind crossover evaluation of a randomized parallel design to determine the efficacy of DPA in 30 subjects with chronic pain from varied etiology which was unrelieved by multiple therapeutic interventions. Each patient received a stabilized therapeutic regimen during this study consisting of four weeks of either DPA 250 mg or lactose (placebo) orally four times a day. After four weeks the DPA and placebo groups were crossed over for an additional four weeks of treatment. Pain was quantified using a visual analog pain scale and a cold pressor test. Data from the pain questionnaires revealed more pain relief on DPA reported by 25% of the patients, more pain relief on placebo reported by 22% of the patients, and no difference in pain relief reported by 53% of the patients. Lowest pain level of the visual analog scale was reported by 47% of the patients on DPA and 53% on placebo. There appears to be no significant analgesic effect from D-phenylalanine in chronic pain patients when compared to placebo.

Animals↗
PubMed1983

Cryogenic damage to peripheral nerves and blood vessels in the rat.

The effects of cryogenic injury on femoral blood vessels and nerves were studied in 28 rats. The femoral neurovascular bundles were dissected out bilaterally and the vessels and nerves subjected to cryogenic injury. The rats were sacrificed at intervals of up to 2 weeks. Damage to the nerves and to a number of femoral vessels was severe and included necrosis and thrombus formation. The results indicate that significant vascular damage can occur during cryotherapy, and the possible complications of this should be considered.

Analgesia↗
PubMed1978

Extradural analgesia revisited. A statistical study.

The results of 334 lumbar extradural analgesics, administered in a standard manner, allowed reassessment of some factors influencing the spread of local anaesthetic solution in the extradural space. There was no evidence of increased spread in patients with degenerative vascular disease when compared with a control group free from such disease. The patient's height and age had a small effect on spread. The results contradict the earlier assumption of a direct relationship between the volume of anaesthetic solution injected and the number of segments blocked.

Adult↗
PubMed1975

Pancuronium and the neonate.

Pancuronium bromide was used safely as the muscle relaxant for neonatal anaesthesia. No untoward effects were seen and the neuromuscular block was successfully reversed in all patients. The potency ratio of pancuronium as compared with tubocurarine ranged from 9:1 at birth to 6:1 at one month of age.

Anesthesia, General↗