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W Espinosa

Publications and source records attributed to W Espinosa.

6 recordsLinked to original sources
PubMed1995

Mathematical analysis of epidural space location.

BACKGROUND: The location of epidural space for local anaesthetic injection can be difficult. The aim of this study was to define the mathematical function of the pressure changes in the syringe during puncture of the epidural space. Knowledge of pressure changes might be of help to the anesthetist who attempts to ascertain the location of the needle, and it is essential to the design of a device with which to locate epidural space. METHODS: Epidural punctures were performed in 20 patients, using an 18-Tuohy needle connected to a 10 ml syringe. The epidural space was located by the loss of resistance technique. Pressure variations within the injection system during epidural puncture were measured and digitized at 250 Hz. Pressure curves were analyzed for amplitude and rate of a decay after entry of the needle into the epidural space. RESULTS: Pressure increased as the needle passed through skin, subcutaneous fat and muscle. The maximal pressure was observed when the needle perforated the ligamentum flavum (689 +/- 124 cm H2O). When the needle entered the epidural space, an exponential decrease in pressure was observed in all patients (R2 = 0.99; tau = 2.1 +/- 0.9 seconds). End-residual pressure was 22 +/- 12 cm H2O. The change in pressure observed when the needle entered the epidural space fitted a negative exponential function (y = e-x/2.08). CONCLUSIONS: Pressures within the injection system for epidural puncture can reach 1100 cm H2O. Location of the epidural space is characterized by an exponential decay to and end-residual pressure below 50 cm H2O, with a constant time of approximately 2 seconds.

Adolescent↗
PubMedDate not supplied

Infraclavicular brachial plexus block: variation in approach and results in 360 cases.

BACKGROUND AND OBJECTIVES: Brachial plexus block is clinically useful. Although the infraclavicular approach to brachial block is the less commonly used form it may offer advantages. We describe the results with three local anesthetic mixtures used during this observational study. METHODS: Three hundred and sixty patients, ASA physical status I and II, scheduled for upper extremity orthopedic surgery, were anesthetized with an infraclavicular brachial plexus block. They were divided into three groups (120 patients each) by type of 40-mL anesthetic mixture: group I had even parts of 2% plain lidocaine and 0.5% bupivacaine with epinephrine 1:200,000; group II had even parts of 1% plain lidocaine and 0.25% bupivacaine with epinephrine 1:200,000; and group III had even parts of 1.5% plain lidocaine and 0.37% bupivacaine with epinephrine 1:200,000. Plexus identification was made by nerve stimulator. The observational assessments were: adequacy and latency time of the block, tourniquet tolerance, postoperative analgesia, local anesthetics doses, sedative doses, complications, and side effects. RESULTS: In groups I, II, and III, adequacy of the block was 95, 75, and 96%, latency time was 10.4, 12.9, and 10.9 minutes, tourniquet tolerance was 99, 84, and 98%, postoperative analgesia time was 663, 331, and 502 minutes, anesthetic doses of lidocaine/bupivacaine were 5.2/1.3, 2.9/0.7 and 4.1/1.1 mg/kg, respectively. Differences were noted between group II and groups I and III (P range: .01-.0001). Sedatives in adequate blocks were midazolam with/without fentanyl (2-3 mg/50-100 microg) in all groups. There were two complication cases with no consequences: two vascular punctures that did not hold up or delay the anesthetic or surgical procedure. There were no clinical manifestations or side effects. CONCLUSIONS: The infraclavicular approach described is effective. It produced reliable anesthesia and is associated with minimal complications and side effects. The mixture of local anesthetics used in group II is not adequate for producing reliable anesthesia.

Adolescent↗
PubMedDate not supplied

[Etomidate perfusion in neurosurgery].

In this prospective study, 20 patients undergoing mean duration (2-3 h) neurosurgical operations on fossa cranii posterior, and cervical and dorsolumbar rachis, were induced with 0.3 mg/kg etomidate bolus dose. To maintain anesthesia, etomidate perfusions at 10 micrograms/kg/min (group I) and 20 microg/kg/min (group II) were administered. Fentanyl at fractionated doses was used as analgesic without association to nitrous oxide and relaxation was achieved with pancuronium bromide. Quality of hypnosis, changes in serum concentration of cortisol as well as hemodynamic and electrolyte changes were evaluated. Serum concentrations of cortisol, glucose, sodium and potassium were measured in basal state, and during perioperative and postoperative period. Hemodynamic status was monitored and side effects were recorded. Patients of group I presented signs of deficient hypnosis consisting of marked sympathetic response. When etomidate perfusion ceased, both groups presented serum concentrations of cortisol under the lower normal limit. Six hours after operation, mean serum concentration of cortisol in group 2 patients was significantly lower than in group I patients; in their samples, a dose-dependent recovery was detected. Serum glucose concentration increased during anesthesia and operation and serum electrolyte concentration remained within normal range during perioperative and postoperative periods. Our results demonstrate that a 20 micrograms/kg/min etomidate infusion is adequate to achieve neuroanesthesia when nitrous oxide administration is contraindicated.

Adult↗
PubMedDate not supplied

[Chemonucleolysis. Peridural anesthesia versus general anesthesia].

A prospective comparative study was carried out between two anesthetic techniques for chemonucleolysis. Patients were divided into 2 groups of 50 patients each. Group A were submitted to general anesthesia and group B to epidural anesthesia with 0.5% bupivacaine, 2% mepivacaine and buprenorphine. Group B was divided into 2 subgroups: in B1, buprenorphine was administered with the local anesthetics, while in B2 buprenorphine was administered postoperatively when pain appeared. Postoperative pain and side effects like anaphylaxis were evaluated. No anaphylactic reactions occurred. Severe lumbar pain appeared in 22% of patients in group A in spite of systematic analgesics, while group B lumbalgia was not severe in any case. Patients in subgroup B1 did not have pain during the 24 first hours and 47.8% of patients in subgroup B2 needed in most of the cases only a dose of buprenorphine. We conclude that epidural anesthesia is a good technique in chemonucleolysis and that the association bupivacaine, mepivacaine and buprenorphine provides a good postoperative pain relief.

Adult↗