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Biomedical subjects

S M Steele

Publications and source records attributed to S M Steele.

At least 19 recordsLinked to original sources
PubMed1998

Lumbar plexus and sciatic nerve block for knee arthroplasty: comparison of ropivacaine and bupivacaine.

PURPOSE: Information about the onset time and duration of action of ropivacaine during a combined lumbar plexus and sciatic nerve block is not available. This study compares bupivacaine and ropivacaine to determine the optimal long-acting local anaesthetic for lumbar plexus and sciatic nerve block in patients undergoing total knee arthroplasty. METHODS: Forty adult patients scheduled for unilateral total knee arthroplasty, under lumbar plexus and sciatic block were entered into this double-blind randomized study. Patients were assigned (20 per group) to receive lumbar plexus block using 30 ml of local anaesthetic and a sciatic nerve block using 15 ml of local anaesthetic with either bupivacaine 0.5% or ropivacaine 0.5%. All solutions contained fresh epinephrine in a 1:400,000 concentration. Every one minute after local anaesthetic injection, patients were assessed to determine loss of motor function and loss of pinprick sensation in the L1-S1 dermatomes. The time to request first analgesic was documented from the PCA pump. This time was used as evidence of block regression. RESULTS: Blocks failed in four patients in each group. The mean onset time of both motor and sensory blockade was between 14 and 18 min in both groups. Duration of sensory blockade was longer in the bupivacaine group, 17 +/- 3 hr, than in the ropivacaine group, 13 +/- 2 hr (P < 0.0001). CONCLUSION: We conclude that bupivacaine 0.5% and ropivacaine 0.5% have a similar onset of motor and sensory blockade when used for lumbar plexus and sciatic nerve block. Analgesic duration from bupivacaine 0.5% was prolonged by four hours compared with an equal volume of ropivacaine 0.5%.

Adult↗
PubMed1998

A comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block.

UNLABELLED: The onset time and duration of action of ropivacaine during an interscalene block are not known. The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. IMPLICATIONS: In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block.

Adult↗
PubMed1998

Use of paravertebral block anesthesia in the surgical management of breast cancer: experience in 156 cases.

OBJECTIVE: To assess safety and efficacy of the regional anesthetic technique paravertebral block for operative treatment of breast cancer, and to compare postoperative pain, nausea, vomiting, and length of hospital stay in patients undergoing breast surgery using paravertebral block and general anesthesia. BACKGROUND: General anesthesia is currently the standard technique used for surgical treatment of breast cancer. Increasing hospital costs have focused attention on reducing the length of hospital stay for these patients. However, the side effects and complications of general anesthesia preclude ambulatory surgery for most patients undergoing breast surgery. In April 1994, the authors initiated the use of paravertebral block anesthesia for patients undergoing primary breast cancer surgery. A review of our early experience revealed that this regional anesthetic technique enables effective anesthesia for operative procedures of the breast and axilla, reduces postoperative nausea and vomiting, and provides prolonged postoperative sensory block that minimizes narcotic requirements. METHODS: A retrospective analysis of 145 consecutive patients undergoing 156 breast cancer operations using paravertebral block and 100 patients undergoing general anesthesia during a 2-year period was performed. Anesthetic effectiveness and complications, inpatient experience with postoperative pain, nausea, vomiting, and length of stay were measured. RESULTS: Surgery was successfully completed in 85% of the cases attempted by using paravertebral block alone, and in 91% of the cases, surgery was completed by using paravertebral block supplemented with local anesthetic. There was a 2.6% incidence of complications associated with block placement. Twenty percent of patients in the paravertebral group required medication for nausea and vomiting during their hospital stay compared with 39% in the general anesthesia group. Narcotic analgesia was required in 98% of general anesthesia patients, as opposed to 25% of patients undergoing paravertebral block. Ninety-six percent of patients having paravertebral block anesthesia were discharged within the day of surgery, compared with 76% of patients who had a general anesthetic. CONCLUSIONS: Paravertebral block can be used to perform major operations for breast cancer with minimal complications and a low rate of conversion to general anesthesia. Paravertebral block markedly improves the quality of recovery after breast cancer surgery and provides the patient with the option of ambulatory discharge.

Anesthesia, General↗
PubMed1990

'Air hunger' from increased PCO2 persists after complete neuromuscular block in humans.

The tolerance of totally curarized subjects for prolonged breath hold is viewed by many as evidence that respiratory muscle contraction is essential to generate the sensation of breathlessness. Although conflicting evidence exists, none of it was obtained during total neuromuscular block. We completely paralyzed four normal, unsedated subjects with vecuronium (a non-depolarizing neuromuscular blocker). Subjects were mechanically ventilated with hyperoxic gas mixtures at fixed rate and tidal volume. End-expiratory PCO2 (PETCO2) was varied surreptitiously by changing inspired PCO2. Subjects rated their respiratory discomfort or 'air hunger' every 45 sec. At low PETCO2 (median 35 Torr) they felt little or no air hunger. When PETCO2 was raised (median 44 Torr) all subjects reported severe air hunger. They had reported the same degree of air hunger at essentially the same PETCO2 before paralysis. When questioned afterwards all subjects said the sensation could be described by the terms 'air hunger', 'urge to breathe', and 'shortness of breath', and that is was like breath holding. They reported no fundamental difference in the sensation before and after paralysis. We conclude that respiratory muscle contraction is not important in the genesis of air hunger evoked by hypercapnia.

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↗
PubMed1989

The role of the clinical nurse specialist in the assessment and development of social-sexual skills of adults who are developmentally disabled.

Clinical nurse specialists (CNSs) functioning in ambulatory settings such as sheltered workshops or other community placements where developmentally disabled persons receive services have an excellent opportunity to use their teaching, counseling and guidance and interaction skills to assist them in gaining competencies that they need to be successful in social/sexual interactions. In this article, preassessment of these skills was performed and an outline of an educational program provided so that CNSs can assume this important teaching and counseling role.

Adult↗
PubMed1980

Torsion of testicular appendages in men.

Torsion of testicular appendages has never been reported in patients more than 18 years old. We herein review 6 surgically proved cases. The possibility of this condition should be considered in the differential diagnosis of scrotal pain and swelling in men.

Adult↗
PubMed1980

Scrotal explorations negative for malignancy.

We reviewed 74 cases of scrotal exploration via an inguinal approach that were negative for malignancy. Of these explorations 24 (32 per cent) resulted in radical orchiectomy and 14 (19 per cent) resulted in simple orchiectomy. An additional 17 patients (23 per cent) had some other operation in addition to exploration. The most frequent final diagnoses were epididymitis (26 per cent), testicular torsion (18 per cent) and hydrocele (15 per cent). These data demonstrate that scrotal explorations to eliminate the possibility of malignancy result in a high orchiectomy rate for benign disease.

Adolescent↗