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Biomedical subjects

M Concepcion

Publications and source records attributed to M Concepcion.

At least 19 recordsLinked to original sources
PubMed2000

Accessory branch of the mental nerve.

This case report presents a surgical case in which an accessory branch of the mental nerve exited the mandible distal and slightly superior to the mental foramen. Careful manipulation of the surgical site allowed proper identification of the mental nerve, and the accessory branch and permanent nerve damage was avoided.

Aged↗
PubMed1994

Upper-airway obstruction and perioperative management of the airway in patients managed with posterior operations on the cervical spine for rheumatoid arthritis.

We reviewed the records of 128 patients who had a total of 128 consecutive posterior operations on the cervical spine for problems related to rheumatoid arthritis. Our purpose was to examine perioperative complications related to the airway. The patients were divided into two groups for analysis on the basis of the technique of intubation that had been used. An upper-airway obstruction developed after extubation in eight (14 per cent) of the fifty-eight patients who had been intubated without fiberoptic assistance compared with one (1 per cent) of the seventy patients who had been intubated fiberoptically (p = 0.02). The two groups had similar characteristics with regard to age, sex, severity of the myelopathy, American Rheumatology Association classification, American Society of Anesthesiologists physical status classification, cigarette use, duration of the arthritis, use of preoperative traction, use of steroids (both preoperatively and intraoperatively), size of the endotracheal tube, duration of the operation, total duration of the anesthesia, intraoperative fluid balance, and type of immediate immobilization of the neck. The only significant difference between the groups was the time to extubation, which averaged 17.9 hours in the fiberoptic group and 10.6 hours in the non-fiberoptic group (p = 0.02). Logistic regression analysis showed that non-fiberoptic intubation was the significant risk factor, even when allowance was made for the difference in the lengths of time to extubation. We concluded that this life-threatening complication can be minimized with fiberoptic management of the airway.

Adult↗
PubMed1991

Respiratory effects of spinal anesthesia: resting ventilation and single-breath CO2 response.

The effects of spinal anesthesia with bupivacaine or lidocaine on resting pulmonary ventilation and on the response to the single-breath carbon dioxide test were studied in 11 unpremedicated patients. Resting end-tidal PCO2 decreased from 34.8 +/- 4.5 (mean +/- SD) to 31.6 +/- 4.6 mm Hg after induction of spinal anesthesia (P = 0.002). The decrease in end-tidal PCO2 correlated negatively with patient age (r = -0.67, P = 0.02) and positively with spinal analgesic level (r = 0.58, P = 0.06). Breath-to-breath variability of ventilation increased during spinal anesthesia. Spinal anesthesia was not associated with statistically significant changes in tidal volume, respiratory rate, minute ventilation, mean inspiratory flow rate, inspiratory duty cycle duration, or the response to the single-breath CO2 test.

Adult↗
PubMed1990

A new local anesthetic, ropivacaine. Its epidural effects in humans.

The current study was initiated to evaluate the epidural anesthetic properties of 0.5%, 0.75%, and 1.0% ropivacaine, a new local anesthetic agent structurally similar to bupivacaine. Fifteen patients scheduled for lower limb orthopedic surgery were enrolled in the study. As the concentration of ropivacaine increased from 0.5% to 1.0%, the time to onset of sensory anesthesia decreased from 6.4 +/- 1.7 (SD) min to 2.4 +/- 0.6 min and the maximum level of sensory anesthesia increased from T6 to T1. These changes were not statistically significant. Time to regression of anesthesia to T12 increased from 255 +/- 73 min with the 0.5% solution to 356 +/- 75 min with 1.0% ropivacaine (P less than 0.05). The degree of motor blockade using the Bromage scale varied with the concentration. When the 0.5% concentration was used, only one patient (20%) had greater than 1+ motor blockade. However, all of the patients receiving the 0.75% or 1.0% solution had at least 2+ motor blockade. Sensory anesthesia was adequate for surgery in 14 of the 15 patients. The mean peak plasma concentration of ropivacaine (Cmax) increased from 0.65 +/- 0.15 micrograms/mL with the 100-mg dose to 1.30 +/- 0.43 microgram/mL with the 200-mg dose. No adverse effects were noted in any patient in the study. These initial studies in humans suggest that ropivacaine provides satisfactory sensory anesthesia with minimal motor blockade at a concentration of 0.5%. An increase in concentration resulted in a more profound motor blockade. The Cmax of ropivacaine in this study was below levels associated with toxicity in animal studies.

Adult↗
PubMed1988

Ventilatory responses to hypercapnia during tetracaine spinal anesthesia.

The effect of spinal anesthesia with hyperbaric tetracaine with epinephrine on resting ventilation and on ventilatory responsiveness to CO2 rebreathing was studied in 10 unpremedicated patients. Resting end-tidal PCO2 (PETCO2) decreased from 37 +/- 3 mmHg (mean +/- SD) to 34 +/- 2 mmHg after induction of spinal anesthesia (p less than 0.05). Minute ventilation (VE) and occlusion pressure (P0.1) at PETCO2 = 55 mmHg increased during spinal anesthesia from 32.0 +/- 12.9 to 40.2 +/- 17.0 l/min and from 5.0 +/- 1.8 to 8.6 +/- 4.7 cmH2O, respectively. The magnitude of the increase in VE during spinal anesthesia correlated inversely with age. Spinal anesthesia was not associated with significant changes in vital capacity, maximal inspiratory pressure, or the slopes of the lines relating VE or P0.1 to PCO2. These results show increased ventilatory responsiveness to CO2 (a parallel leftward shift of the CO2 response curve) with tetracaine spinal anesthesia.

Adult↗
PubMed1988

Ventilatory responses to hypercapnia during bupivacaine spinal anesthesia.

The effect of spinal anesthesia with isobaric 0.5% bupivacaine on ventilatory responsiveness to CO2 rebreathing was studied in ten unpremedicated patients. Minute ventilation (VE) at end-tidal PCO2 = 55 mm Hg increased from 18.7 +/- 6.7 L/min (mean +/- SD) to 22.3 +/- 10.1 L/min after induction of spinal anesthesia (P less than 0.05). Occlusion pressure (P0.1) at PCO2 = 55 mm Hg also increased, from 3.8 +/- 1.5 to 5.0 +/- 1.7 cm H2O (P less than 0.05). Spinal anesthesia was not associated with significant changes in vital capacity, maximal inspiratory pressure, resting end-tidal PCO2, or the slopes or intercepts of the lines relating VE or P0.1 to PCO2. These results show an increased ventilatory responsiveness to CO2 with bupivacaine spinal anesthesia.

Adult↗
PubMed1986

Plasma and cerebrospinal fluid progesterone concentrations in pregnant and nonpregnant women.

Pregnancy is associated with a wider dermatomal spread of local anesthetics after epidural and spinal anesthesia. This phenomenon also exists in the immediate postpartum period. The mechanism of this observation is unresolved. However, an increase in progesterone concentration in pregnancy has been implicated as one of the factors. Although plasma progesterone concentrations in humans have been well-documented, the cerebrospinal fluid (CSF) progesterone levels, which may also be important in this regard, have not been determined. Therefore, this study was undertaken to measure plasma and CSF progesterone in the nonpregnant, term parturient and in the immediate postpartum patient and also to determine the relationship between the CSF progesterone concentration and the intrathecal spread of lidocaine used for spinal anesthesia. The plasma progesterone concentrations in 12 nonpregnant, 21 term and eight postpartum patients were 2.3 +/- 61 (SEM) ng/ml, 122 +/- 8 ng/ml and 16 +/- 2.2 ng/ml, respectively. The CSF progesterone concentrations in term parturients (3 +/- 0.28 (SEM) ng/ml) and postpartum patients (1.03 +/- 0.16 ng/ml) were eight and three times greater than that of nonpregnant women (0.39 +/- 0.01 ng/ml). Significantly less lidocaine was needed (P less than 0.05) for comparable segmental levels of spinal anesthesia in term and postpartum patients than in nonpregnant individuals. These data suggest that high CSF, plasma progesterone concentrations, or both may augment the anesthetic spread of lidocaine.

Adolescent↗
PubMed1986

Epidural morphine provides postoperative pain relief in peripheral vascular and orthopedic surgical patients: a dose-response study.

A randomized double-blind study compared the dose-response relationship of epidural morphine for postoperative pain relief in two groups of patients whose surgical procedures would result in either moderate (femoral-popliteal bypass) or severe (total knee replacement) postoperative pain. Preservative-free morphine sulphate in doses of 0, 2, 5, or 10 mg in a volume of 10 ml saline were administered via lumbar epidural catheters. The epidural morphine was administered 1 hr after the last dose of intraoperative local epidural anesthetic in an effort to achieve a pain-free postoperative course. A significant relationship existed between the dose of epidural morphine and both time to first required pain medication and 24-hr weighted pain score. Five mg epidural morphine provided significant improvement in postoperative analgesia compared with the control in both groups. Further enhancement of analgesia occurred with 10 mg; however, late respiratory depression, demonstrated by an increased resting PaCO2 10 hr after administration, was seen only with the 10-mg dose in both surgical groups. Minor complications such as nausea, vomiting, pruritus, and urinary retention were uncommon and did not appear to be related to dose. We found that 5 mg epidural morphine provided long-lasting postoperative analgesia without serious adverse effects after peripheral vascular and orthopedic surgery.

Adult↗
PubMed1984

Rational use of local anaesthetics.

The judicious use of local anaesthetic agents requires knowledge of the pharmacological properties of the various drugs, technical skill in the performance of the different nerve blocks, and a thorough evaluation of the patient's clinical status. Regional anaesthesia may be classified anatomically as follows: (a) infiltration anaesthesia (extravascular or intravascular); (b) peripheral nerve blockade (minor or major nerve block); and (c) central neural blockade (epidural or subarachnoid block). Anaesthetic potency, onset time and duration of action are the most important clinical properties of any local anaesthetic agent. In general, onset of anaesthesia occurs most rapidly during infiltration techniques and subarachnoid administration, followed in order of increasing onset time by minor nerve blockade, epidural block and major nerve blocks. Duration of anaesthesia is most prolonged when major nerve blockade is performed, followed in order of decreasing duration by epidural and infiltration procedures, minor nerve and subarachnoid blocks. The local anaesthetic agents commonly employed for regional anaesthesia may be classified according to their relative potency and duration of activity into: (1) agents of low potency and short duration, e.g. procaine and chloroprocaine; (2) agents of moderate potency and duration, e.g. lignocaine (lidocaine), mepivacaine and prilocaine; and (3) agents of high potency and long duration, e.g. amethocaine (tetracaine), bupivacaine and etidocaine. In general, the onset, duration and quality of regional anaesthesia are enhanced by an increase in dose achieved by either an increase in concentration or in the volume of anaesthetic solution, and by the concomitant use of a vasoconstrictor drug, adrenaline (epinephrine). However, the local anaesthetic properties of the intrinsically more potent and longer acting agents are influenced less by the addition of adrenaline, particularly when such agents are employed for central neural blockade of the epidural type.

Anesthesia, Conduction↗
PubMed1984

Vasoconstrictors in spinal anesthesia with tetracaine--a comparison of epinephrine and phenylephrine.

A randomized double-blind study was conducted in 50 orthopedic patients to determine the effect of epinephrine and phenylephrine on the anesthetic properties of intrathecally administered tetracaine. Two doses of each vasoconstrictor agent were studied: 0.2 mg of epinephrine, 0.3 mg of epinephrine, 1 mg of phenylephrine, and 2 mg of phenylephrine. The results show that both vasoconstrictor agents in the doses used significantly prolong duration of sensory anesthesia and motor blockade produced by the subarachnoid administration of tetracaine. At equipotent doses no differences existed between the ability of epinephrine and phenylephrine to prolong the duration of spinal anesthesia produced by tetracaine.

Adult↗
PubMed1982

Intermediate variables and educational differentials in fertility in Korea and the Philippines.

This analysis compares the effects of contraceptive use and infant and fetal mortality on the pace of fertility in Korea and the Philippines and explores the mediating effects of these intermediate variables on educational differentials in childspacing. For both intervals initiated in a recent period before a sample survey, second, third and higher-order intervals are examined. Transitions within successive segments of interval exposure (qx values) are examined rather than cumulative transitions (1 - lx values). This methodological choice is substantively important because breastfeeding should primarily affect early segments of exposure and because it allows empirical examination of the timing of the effects of other variables such as contraceptive use. Further, this choice allows multivariate analysis within the structure of the life-table perspective. The results show substantial differences in patterns between Korea and the Philippines, indicate clearly the effect of each intermediate variable, and illustrate how educational differentials in fertility are affected by contraception and infant and fetal mortality.

Adult↗
PubMedDate not supplied

Evaluation of a new cutaneous topical anesthesia preparation.

Topical anesthetic agents are usually not effective on intact skin because of poor penetration. EMLA is a new topical anesthetic formulation consisting of a eutectic mixture of the local anesthetics lidocaine 5% and prilocaine 5%. We evaluated the ability of this preparation to prevent or ameliorate the pain associated with the percutaneous placement of large IV catheters. Under double-blind randomized conditions, either EMLA or placebo was applied to the dorsum of both hands and an occlusive bandage then placed over each application site. The creams were placed 30, 45 or 60 minutes prior to IV cannulation. A 16-gauge catheter was inserted through each application area. Patients were asked to evaluate the relative degree of pain at each venous puncture site. The EMLA site was preferred when the formulation was applied for 45 to 60 minutes prior to cannula placement (p less than 0.01, confidence limits for the binomial distribution). Cusum analysis confirmed this minimal effective application time. The results indicate that EMLA is an effective cutaneous anesthetic formulation when applied with an occlusive bandage for a minimal time period of 45 minutes.

Anesthetics, Local↗