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Biomedical subjects

S Ramamurthy

Publications and source records attributed to S Ramamurthy.

83 records · Page 5Linked to original sources
PubMedDate not supplied

Lidocaine hydrocarbonate is not superior to lidocaine hydrochloride in interscalene brachial plexus block.

To determine the effect of carbonation of lidocaine, a comparison of 1.0% lidocaine hydrochloride (HCl) and 1.1% lidocaine hydrocarbonate (CO2), both with 1:200,000 epinephrine, was made in this study of 50 patients receiving interscalene brachial plexus blocks. Sensory block was determined by the response to pinprick in the C2-T2 dermatomes, while motor block was assessed by the development of paresis and paralysis at the shoulder and hand. The percentage of patients developing analgesia (decreased sensation to pinprick) and anesthesia (total absence of sensation to pinprick) at each dermatome level as well as the percentage of patients developing motor block was not significantly different between the two forms of lidocaine. The initial onset of analgesia [lidocaine HCl, 4.0 +/- 2.4 (SD) minutes; lidocaine CO2, 4.3 +/- 3.8 (SD) minutes] and anesthesia [lidocaine HCl, 10.1 +/- 5.7 (SD) minutes; lidocaine CO2, 7.8 +/- 4.4 (SD) minutes] did not differ significantly between the two groups. At the individual dermatomes, there was no difference in the onset of analgesia except at one dermatome level, C7, which was near the level of local anesthetic injection. Anesthesia onset in each dermatome as well as the onset of motor block did not differ between the two groups. It is concluded that lidocaine CO2 does not offer any significant clinical advantage over lidocaine HCl in interscalene brachial plexus block.

Adult↗
PubMedDate not supplied

Transarterial techniques are not effective for subclavian perivascular block.

Although transarterial techniques have been commonly used for axillary block, results with these techniques have not been previously described for subclavian perivascular block. We studied the efficacy and complications of two types of arterial techniques for subclavian perivascular block. In Group 1 (n = 10), the subclavian perivascular injection was made after withdrawing the needle from the subclavian artery (top of artery), and in Group 2 (n = 8), the injection was made after advancing through the subclavian artery (bottom of artery). The local anesthetic used was lidocaine 1.5% with epinephrine 1:200,000 in a volume determined by the formula [ml = (height in inches divided by 2) + 5]. Both techniques were associated with a low incidence (50% or less) of anesthesia throughout the brachial plexus dermatomes. Sixty percent of patients in Group 1 and 63% of patients in Group 2 required supplemental blocks. In view of the low incidence of anesthesia and the frequent need for supplementation, additional patients were not enrolled in the study. Complications associated with the technique included hematoma (12-20%), recurrent laryngeal nerve block (10-25%), Horner's syndrome (0-20%) and phrenic nerve block (75-80%). Despite the relatively high dose of lidocaine used, serum lidocaine levels remained well below the toxic range.

Aged↗
PubMedDate not supplied

Identification of the anterior psoas sheath as a landmark for lumbar sympathetic block.

This clinical report demonstrates that identification of the psoas muscle via contrast media injection under fluoroscopy and the subsequent tenting and puncture of the psoas fascia with a 6-inch 22-gauge needle is a definite aid in the correct placement of the needle for lumbar sympathetic block. In ten patients in whom this technique was used, the needle position was subsequently proven to be correctly placed in all cases. The authors conclude that this method is a valuable adjunct in fluoroscopy-guided lumbar sympathetic block.

Autonomic Nerve Block↗
PubMedDate not supplied

Collateral arteries in the presence of obstructive coronary disease.

BACKGROUND: The clinical importance of coronary collaterals in the presence of obstructive coronary artery disease is not clearly defined. METHODS: We retrospectively analysed the clinical and angiographic features of 100 patients with > or = 90% luminal diameter stenosis involving at least one major coronary artery. Coronary collaterals were graded 0 to 4 (Nitzberg's classification) and studied to determine their influence on clinical parameters. RESULTS: Thirty patients had no collaterals (group I) and 70 showed collaterals (group II). There were no significant differences between groups I and II in age and sex distribution, prevalence of risk factors of coronary artery disease (hypertension, diabetes, smoking, hypercholesterolaemia), duration of symptoms of coronary artery disease and prior myocardial infarction. Groups I and II had similar types (left anterior descending 73% v. 71%; left circumflex 50% v. 50% and right coronary 37% v. 56%) and numbers of arteries involved (one 47% v. 41%; two 47% v. 40%; three 7% v. 19%). Group II had a significantly lower prevalence of rest angina (14% v. 47%, p = 0.002). This difference was also evident when the patients were re-classified according to the extent of flow through the collaterals. Those with good collateralization (Nitzberg grades 3 and 4) had a lower prevalence of rest angina (13%) compared to those with poor collateralization (Nitzberg grades 0 to 2; 35%, p = 0.02). CONCLUSION: Coronary artery collaterals may reduce the incidence of rest angina in patients with obstructive coronary artery disease.

Angina Pectoris↗
PubMedDate not supplied

A pharmacokinetic study of phenylcyclohexyldiethylamine. An analog of phencyclidine.

The pharmacokinetics of three phencyclidine analogs--phenylcyclohexyl-diethylamine (PCDE), phenylcyclohexylethylamine (PCE), and phenylcyclohexylamine (PCA)--were determined in rats after intravenous administration of each drug. Because PCE and PCA are major metabolites of PCDE, their plasma levels were also measured after administration of PCDE. Similarly, PCA concentrations was determined after administration of PCE. The data were combined and analyzed by nonlinear regression procedures using compartmental and noncompartmental models to determine the kinetic parameters of PCDE metabolism. The object was to estimate the kinetic constants for the metabolic sequence, PCDE to PCE to PCA. A 6-compartment model (two pools for each analyte) that included saturable components for the conversion of PCDE to PCE and PCE to PCA gave the best fit to the combined data. Despite large uncertainties for some microparameters, useful estimates were obtained for clearances, distribution volumes, and fraction of PCDE or PCE converted to PCE and PCA in vivo under nonsaturating conditions. The estimated fraction of PCDE converted to PCA and the apparent Km value for the conversion of PCDE to PCE were comparable to values obtained in vitro with microsomal preparations, suggesting that metabolic studies in vitro provide reasonable predictors of the biotransformation process in vivo for this class of compounds.

Animals↗
PubMedDate not supplied

Comparison of the clinical efficacy of three perivascular techniques for axillary brachial plexus block.

BACKGROUND AND OBJECTIVES: This study compared the efficacy of three perivascular techniques of axillary block. METHODS: In group 1, all of the local anesthetic was injected after advancing the needle through the axillary artery (back of artery, n = 20); in group 2, after withdrawing slightly from the artery (front of artery, n = 20); and in group 3, half of the anesthetic was injected after advancing through and half after withdrawing from the axillary artery (half and half, n = 20). The local anesthetic used for the axillary block was 50 ml of 1.5% mepivacaine with epinephrine 1:200,000. RESULTS: The groups did not differ significantly in the incidence of analgesia or anesthesia expected in the median nerve distribution, where there was a significantly lower incidence of anesthesia in the back of the artery group. This group also had a slower onset of anesthesia for the median and the medial antebrachial cutaneous nerves. CONCLUSIONS: There was no significant difference in the number of patients requiring supplementation, with five patients in the back group (25%), three patients in the front group (15%), and one patient in the half and half group (5%) requiring supplementation for the surgical procedure.

Adult↗
PubMedDate not supplied

Incidence of genitofemoral nerve block during lumbar sympathetic block: comparison of two lumbar injection sites.

BACKGROUND AND OBJECTIVES: Genitofemoral nerve (GFN) block is a known side effect of a lumbar sympathetic block (LSB), although the incidence has not been well documented. Furthermore, genitofemoral neuralgia can occur following neurolytic LSB. Because the level at which the GFN exits the psoas sheath varies, this study was designed to identify differences in the incidence of GFN block following LSB at the level of the second versus the fourth lumbar vertebrae. METHODS: Patients requiring LSB to evaluate chronic lower extremity pain were prospectively studied. Patients were injected at the second lumbar (L2 group) or fourth lumbar (L4 group) vertebral body depending on the location of the pain syndrome in the lower extremity. Lumbar sympathetic blocks were performed using 10 mL of a 0.5% bupivacaine solution with radiocontrast; spread of injectate was verified using fluoroscopy. An observer evaluating for presence of GFN block was blinded to the lumbar level of injection. RESULTS: Thirty patients were enrolled (L2 group, n = 15; L4 group, n = 15). Spread of local anesthetic/radiocontrast solution was limited to approximately one vertebral body above and one below the target level. There was no difference in the ability to achieve a LSB; success rates were 66% and 73% using L2 and L4, respectively. The incidence of GFN block was 0% (0/15) in the L2 group versus 40% (6/15) in the L4 group; this was statistically significant (P = .017, Fisher's exact test). CONCLUSIONS: The GFN is less likely to be blocked when the LSB is performed near the second lumbar vertebra as compared with the fourth lumbar vertebra.

Adult↗