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Biomedical subjects

S C Walker

Publications and source records attributed to S C Walker.

At least 19 recordsLinked to original sources
PubMed1997

Healing rates of diabetic foot ulcers associated with midfoot fracture due to Charcot's arthropathy.

The aim of this study is to compare the effectiveness of total contact casts based on wound location in groups of patients with diabetes mellitus with neuropathic ulcerations under the forefoot and patients with midfoot ulcerations associated with acute Charcot's arthropathy. Twenty-five consecutive diabetic patients with Meggitt-Wagner grade I neuropathic foot ulceration (NU) and 22 consecutive diabetic patients with neuropathic ulceration and acute Charcot's arthropathy (CU) were selected for study. Larger wounds took longer to heal in both the CU (p < 0.0001) and NU groups (p < 0.0001). Duration of ulcer prior to treatment also was significantly associated with increased healing time in both groups (p = 0.008 NU, p = 0.03 CU). The CU group had larger wounds (10.3 +/- 4.6 vs 7.7 +/- 4.0 cm2, p = 0.04) but took significantly less time to heal (28.4 +/- 13.0 vs 38.8 +/- 21.3 days, p = 0.04) than did subjects with neuropathic ulcerations only. The NU group had their ulcers present for a significantly longer period of time prior to contact casting (88.5 +/- 98.3 vs 17.7 +/- 12.9 days, p = 0.001). In this study, subjects with ulcerations secondary to acute Charcot fractures healed more rapidly than in previous reports with healing times of forefoot neuropathic ulcers similar to previous studies. Every patient's ulcer healed. There were no cast-related ulcerations, infections, or hospitalizations. Concerns regarding the safety of total contact casts to treat well-vascularized superficial forefoot and midfoot plantar wounds appear to be unfounded.

Adult↗
PubMed1997

Gait pattern alteration by functional sensory substitution in healthy subjects and in diabetic subjects with peripheral neuropathy.

OBJECTIVE: To evaluate the ability of diabetic and nondiabetic individuals to learn to use a lower extremity sensory substitution device to cue gait pattern changes. DESIGN: Case-control study. SETTING: Gait laboratory. PARTICIPANTS: Thirty diabetic persons and 20 age- and education-matched nondiabetic controls responded to advertisements for study participation. INTERVENTION: Participants walked on a treadmill at three speeds (1, 2, and 2.5mph) with auditory sensory feedback to cue ground contact greater than 80% duration of baseline. MAIN OUTCOME MEASUREMENTS: The variables measured included gait cycle (steps per minute) and number of times per minute that any step during a trial exceeded 80% duration of ground contacted compared with a measured baseline step length for each speed. RESULTS: Persons in both groups were able to rapidly and significantly alter their gait patterns in response to signals from the sensory substitution device, by changing their gait cycles (nondiabetic group, F(17,124) = 5.27, p < .001; diabetic group, F(5,172) = 3.45, p < .001). Post hoc analyses showed early gait cycle modification and error reduction among both groups. The nondiabetic group learned to use the device significantly more quickly than the diabetic group during the slow (1mph, t = 3.57, p < .001) and average (2mph, t = 2.97, p < .05) trials. By the fast (2.5mph) ambulation trial, both groups were performing equally, suggesting a rapid rate of adjustment to the device. No technical failures from gait trainer malfunction occurred during the study. CONCLUSIONS: Diabetic persons with neuropathy effectively used lower extremity sensory substitution, and the technology is now available to manufacture a durable, effective lower extremity sensory substitution system.

Adult↗
PubMed1997

Mortality following lower extremity amputation in minorities with diabetes mellitus.

The aim of this study was to identify the age adjusted and level specific mortality rate in African-Americans, Hispanics and non-Hispanic whites (NHW) during the perioperative period following a lower extremity amputation. We identified amputation data obtained from the Office of Statewide Planning and Development in California for 1991 from ICD-9-CM codes 84.11-84.18 and diabetes mellitus from any 250 related code. Amputations were categorized as foot (84.11-84.12), leg (84.13-84.16) or thigh (84.17-84.18). Death was coded under discharge status. Age adjusted and level specific mortality rates per 1000 amputees were calculated for each race/ethnic group. The age adjusted mortality was highest for African-Americans (41.39) compared to Hispanics (19.69) and NHW's (34.98). Mortality was consistently more frequent for proximal amputations. We conclude that mortality rates for persons with diabetes hospitalized for an amputation varied by race, gender and level of amputation. Higher prevalence or severity of risk factors may explain the excess mortality observed in African-Americans.

Adult↗
PubMed1997

Tracheal intubation using alfentanil and no muscle relaxant: is the choice of hypnotic important?

Administration of alfentanil followed by propofol intravenously (IV) without neuromuscular blockade for induction of anesthesia provides adequate conditions for tracheal intubation. Other hypnotic drugs have not been thoroughly investigated in this regard. Accordingly, 140 ASA physical status I and II premedicated outpatients were randomly assigned to one of seven groups (n = 20/group). Patients in Groups I-VI received alfentanil 40 microg/kg followed by etomidate 0.3 mg/kg, propofol 2 mg/kg, or thiopental 4 mg/kg. One half of these patients (Groups II, IV, VI) also received lidocaine 1 mg/kg IV prior to the administration of the above drugs. Patients in group VII received d-tubocurarine 3 mg followed by thiopental 4 mg/kg and succinylcholine 1 mg/kg. Ninety seconds after induction, laryngoscopy and endotracheal intubation were attempted and graded. Patients in Group V (alfentanil/thiopental) were significantly (P < 0.05) more likely to have a clinically unacceptable response to intubation (55%) (e.g., vigorous coughing, purposeful movement, or requirement for succinylcholine to complete intubation) compared with patients who received propofol (35%) or etomidate (20%). Alfentanil/etomidate yielded intubation conditions comparable to those achieved with alfentanil/propofol and d-tubocurarine/thiopental/succinylcholine. Lidocaine appeared to improve intubating conditions, although this improvement did not reach statistical significance. The results suggest that healthy, premedicated patients with favorable airway anatomy who have received alfentanil 40 microg/kg can be reliably tracheally intubated 90 s after administration of propofol 2 mg/kg or etomidate 0.3 mg/kg.

Adult↗
PubMed1997

The clinical neuromuscular pharmacology of cisatracurium versus vecuronium during outpatient anesthesia.

UNLABELLED: Neither comparisons of the clinical neuromuscular effects of cisatracurium and vecuronium nor comparative studies of their antagonism by neostigmine have been reported. In addition, the efficacy of administering cisatracurium in divided doses has not been investigated. Accordingly, we applied supramaximal electrical stimuli to the ulnar nerve of 165 ASA physical status I and II patients receiving nitrous oxide/alfentanil/propofol anesthesia. Forty-five patients received cisatracurium 5, 10, or 15 microg/kg, and the evoked response at the adductor pollicis was recorded for 15 min. One hundred-twenty patients received cisatracurium 5, 10, or 15 microg/kg or normal saline placebo followed 5 min later by either cisatracurium 100 microg/kg or vecuronium 100 microg/kg (always after placebo). Time to clinical onset (maximal ablation of single twitch response) was measured. When the evoked response spontaneously recovered to 10% of control height, neostigmine 5, 10, 30, or 50 microg/kg or placebo was administered, and recovery of neuromuscular function was recorded for the next 15 min. The clinical onset of vecuronium without priming (2.8 +/- 0.8 min) (mean +/- SD) was significantly (P < 0.05) faster than the onset of cisatracurium without priming (4.6 +/- 1.4 min). Cisatracurium 5, 10, or 15 microg/kg administered before cisatracurium 100 microg/kg significantly (P < 0.05) accelerated the time to complete ablation of the evoked response (3.9 +/- 0.9, 2.9 +/- 0.8, or 3.0 +/- 0.9 min, respectively) compared with cisatracurium 100 microg/kg without priming. The dose of neostigmine required to achieve 50% assisted recovery of the train-of-four ratio at 5 min was significantly (P < 0.05) smaller in patients who received vecuronium (29.1 [17.9-55.3] microg/kg) (mean [95% confidence interval]) compared with those who received cisatracurium (53.7 [31.6-131.5] microg/kg). Given its faster clinical onset and greater sensitivity to antagonism by neostigmine, we conclude that vecuronium may be more suitable than cisatracurium for use in outpatient anesthesia. IMPLICATIONS: We investigated the onset of muscle relaxation using intravenous vecuronium and cisatracurium and assessed the ability of neostigmine to antagonize (reverse) this effect. Our results suggest that vecuronium works faster than cisatracurium and is more sensitive to neostigmine. Vecuronium therefore may be more useful than cisatracurium in outpatient anesthesia.

Adolescent↗
PubMed1997

Surgical morbidity and the risk of amputation due to infected puncture wounds in diabetic versus nondiabetic adults.

We reviewed the hospital course of 77 diabetic and 69 nondiabetic subjects who had incision, drainage, and exploration of infected puncture wounds of the foot. Diabetics were 5 times more likely to have multiple operations and 46 times more likely to have a lower extremity amputation than nondiabetics. The interval from injury to surgery was significantly longer in diabetics than nondiabetics. Total lymphocyte count and hemoglobin, hematocrit, and albumin values were significantly lower in diabetics than in nondiabetics. Diabetic amputees had higher prevalences of nonpalpable pulses, nephropathy, neuropathy, and osteomyelitis as compared with diabetic nonamputees. The neuropathic diabetic foot is not protected by pain. When combined with other comorbid factors, this may increase morbidity associated with puncture wounds of the foot.

Adult↗
PubMed1997

The haemodynamic effects of rocuronium and vecuronium are different under balanced anaesthesia.

BACKGROUND: Rocuronium has been reported to have minimal haemodynamic effects. However, this conclusion has been drawn primarily from investigations conducted under narcotic-based anaesthesia. This study was designed to evaluate the cardiovascular effects of rocuronium under isoflurane/N2O/fentanyl anaesthesia and to compare rocuronium's haemodynamic effects to those of vecuronium and pancuronium. METHODS: Anaesthesia was induced with fentanyl 2 micrograms/kg, thiopentone 4 mg/kg, and suxamethonium 0.5 mg/kg in 75 ASA I or II patients. After tracheal intubation, anaesthesia was maintained with isoflurane 0.5% and N2O 50% in oxygen. Five min after intubation (baseline), patients randomly received either vecuronium 100 micrograms/kg, rocuronium 600 micrograms/kg, rocuronium 900 micrograms/kg, rocuronium 1200 micrograms/kg, or pancuronium 140 micrograms/kg. One min after administration of muscle relaxant, mean arterial pressure (MAP) and heart rate (HR) were recorded and were subsequently measured at 1-min intervals for the next 4 min. RESULTS: HR decreased significantly (P < 0.05) at all times compared to baseline in patients receiving vecuronium. HR significantly (P < 0.05) increased in those receiving rocuronium 1200 micrograms/kg or pancuronium. Patients who received vecuronium had a significant (P < 0.05) decrease in MAP at all times compared to baseline. Comparing results between groups, patients who received rocuronium or pancuronium had significantly (P < 0.05) higher MAP compared to those administered vecuronium. CONCLUSION: The haemodynamic effects of rocuronium and vecuronium are different under balanced anaesthesia. Rocuronium may attenuate the fall in MAP that often occurs under balanced anaesthesia without surgical stimulation.

Adolescent↗
PubMed1997

Surgical morbidity and the risk of amputation due to infected puncture wounds in diabetic versus nondiabetic adults.

We reviewed the hospital course of 77 diabetic and 69 nondiabetic subjects who had incision, drainage, and exploration of infected puncture wounds of the foot. Diabetics were 5 times more likely to have multiple operations and 46 times more likely to have a lower extremity amputation than nondiabetics. The interval from injury to surgery was significantly longer in diabetics than nondiabetics. Total lymphocyte count and hemoglobin, hematocrit, and albumin values were significantly lower in diabetics than in nondiabetics. Diabetic amputees had higher prevalences of nonpalpable pulses, nephropathy, neuropathy, and osteomyelitia as compared with diabetic nonamputees. The neuropathic diabetic foot is not protected by pain. When combined with other comorbid factors, this may increase morbidity associated with puncture wounds of the foot.

Adult↗
PubMed1996

A mixture of mivacurium and rocuronium is comparable in clinical onset to succinylcholine.

STUDY OBJECTIVES: To compare the clinical onset and duration of a combination of mivacurium and rocuronium with succinylcholine, and to determine the efficacy of this mixture for rapid tracheal intubation. DESIGN: Observer-blind prospective study. SETTING: Teaching hospital. PATIENTS: 70 ASA status I and II patients having general anesthesia for elective surgery. MEASUREMENTS AND MAIN RESULTS: After induction of general anesthesia, patients randomly received succinylcholine 1.0 mg/kg, rocuronium 0.6 mg/kg, or a combination of rocuronium 0.6 mg/kg and mivacurium 0.15 mg/kg. Evoked muscular response at the adductor pollicis was measured by mechanomyography. The time from injection of muscle relaxant(s) to ablation of T1 (clinical onset) and recovery of T1 to 25% of control height (clinical duration) was recorded. Intubating conditions 45 seconds after administration of muscle relaxants were assessed. There was no significant difference in clinical onset time between succinylcholine (mean +/- SD, 47.4 +/- 6.5 seconds) and the combination of mivacurium-rocuronium (51.2 +/- 13.4 seconds). Intubating conditions with mivacurium-rocuronium were comparable to those of succinylcholine. The clinical duration of rocuronium 0.6 mg/kg (38.9 +/- 12.3 minutes) was prolonged by the addition of mivacurium (49.0 +/- 9.6 minutes). CONCLUSIONS: This combination of mivacurium and rocuronium is comparable to succinylcholine in both clinical onset time and quality of intubating conditions. When rapid onset of dense neuromuscular blockade and intermediate clinical duration is desirable, this mixture may be an acceptable alternative to succinylcholine.

Adjuvants, Anesthesia↗
PubMed1996

Puncture wounds: normal laboratory values in the face of severe infection in diabetics and non-diabetics.

PURPOSE: Using infected puncture wounds as a basis for comparison, we pose the question of whether white blood cell count (WBC) and erythrocyte sedimentation rate (ESR) is lower in diabetic patients with foot infections as compared with nondiabetic patients. PATIENTS AND METHODS: This case control study consisted of two groups, both with infected puncture wounds of the foot, admitted to a 700-bed urban university teaching hospital between 1985 and 1992. The experimental group contained 77 patients with diabetes mellitus. The control group consisted of 69 patients without diabetes. All subjects received emergent incision and drainage of the affected site. RESULTS: Results revealed a normal WBC count in 57.6% of patients. The ESR was normal in 36.3% of admissions. More nondiabetic patients presented with normal ESR than diabetic patients (62.3% versus 13.7%, respectively; P < 0.0001). Diabetic patients had a significantly higher mean WBC count and ESR than did nondiabetic patients. Pain was the principal complaint more frequently in nondiabetic patients (92.9% NDM versus 70.1% DM, respectively; P < 0.005). Erythema (72.7% versus 51.4%; P = 0.008), and drainage (36.4% versus 7.1%; P < 0.001) were more common in diabetic patients. CONCLUSION: We conclude that, while a glaringly elevated WBC count or ESR should alert the clinician to the possibility of infection, normal values should not be relied upon to rule out a serious event.

Adult↗
PubMed1996

Nebulized tetracaine attenuates the hemodynamic response to tracheal intubation.

BACKGROUND: Local anesthetics, principally lidocaine, are commonly administered in an attempt to blunt the hemodynamic response to tracheal intubation. There are no prior investigations evaluating the use of tetracaine in this setting. METHODS: In the present study, 30 female patients (ASA I-II) scheduled for elective surgery were randomized to receive inhaled nebulized tetracaine 0.5 mg/kg or nebulized saline. Subsequently, anesthesia was induced with thiopental 5mg/kg and succinylcholine 1.0 mg/kg. Sixty seconds later, the trachea was intubated. Vital signs were recorded at intubation and at 1-minute intervals for the next 5 minutes. RESULTS: Patients treated with tetracaine had a significantly (P < 0.05) lower mean heart rate at intubation and all subsequent times. Similarly, there were significant differences (P < 0.05) in mean arterial pressure between tetracaine and control patients at all times post-intubation except at 2 minutes. The inhalation of nebulized tetracaine produced no adverse side effects. CONCLUSION: We conclude that nebulized tetracaine significantly attenuates the hemodynamic response to tracheal intubation.

Administration, Topical↗
PubMed1995

Incorporation of 5-bromo-2'-deoxyuridine into colorectal liver metastases and liver in patients receiving a 7-day hepatic arterial infusion.

Preclinical and clinical data suggest that the combination of hepatic arterial bromodeoxyuridine (BrdUrd), a thymidine analogue radiation sensitizer, and high-dose three-dimensional conformal radiation therapy offer a high potential for improving the local control of intrahepatic cancers. A key step in the design of a successful protocol is to determine in patients the conditions for BrdUrd administration that would be expected to produce selective radiosensitization of the tumor. Therefore, we designed a clinical trial to assess BrdUrd incorporation into the DNA of hepatic colorectal metastases and normal liver after a 7-day continuous BrdUrd infusion at a dose rate of 25 mg/kg/day (the maximal tolerated dose for a 14-day infusion) for patients undergoing laparotomy for either resection of liver metastases or hepatic arterial catheter and pump placement. Thirteen patients were entered into this study. We found that the average replacement of thymidine by BrdUrd in the tumor and normal liver were 11.6 +/- 1.2% and 1.1 +/- 0.2%, respectively. This extent of incorporation would be expected to produce a single fraction radiation enhancement of 1.5 in the tumor without detectable sensitization of the normal liver. Immunohistochemical staining for BrdUrd revealed heterogeneity of incorporation with a range of approximately 60-80% of the cells labeled in different regions of the specimens. These findings suggest that hepatic arterial BrdUrd given at this dose and schedule has a high likelihood of producing clinically significant radiosensitization for patients with hepatic metastases from colorectal cancer. Furthermore, the demonstrated selectivity of tumor perfusion that can be obtained with hepatic arterial infusion combined with the high proliferative rate of colorectal metastases (versus normal liver) suggests that these patients may be good candidates for tumor-directed gene transfer therapy by using regionally delivered retroviral vectors.

Adult↗
PubMed1995

Infected puncture wounds in diabetic and nondiabetic adults.

OBJECTIVE: To evaluate bone and soft tissue pathogens resulting from puncture wounds among diabetic and nondiabetic adults. RESEARCH DESIGN AND METHODS: We used a case-control design to compare bacterial pathogens in diabetic and nondiabetic subjects with foot infections precipitated by puncture injuries. We used ICD-9-CM code E920.8 to identify 77 diabetic and 69 nondiabetic patients admitted to the hospital for infected puncture wounds. We identified surgical bone and soft tissue cultures and number and type of organisms per culture. RESULTS: Nondiabetic subjects had significantly less osteomyelitis (13 vs. 35%, P < 0.01) than diabetic subjects and were infected by fewer organisms. Pseudomonas was the most common cause of osteomyelitis among nondiabetic subjects (P < 0.001). Staphylococcus aureus was more common in diabetic bone (P < 0.001) and soft tissue (P < 0.001) infections. Polymicrobial osteomyelitis was more common in diabetic subjects. There was a longer delay until diabetic subjects received medical treatment compared with nondiabetic subjects (8.7 vs. 5.3 days, P < 0.002). Diabetic subjects were more likely to have neuropathy (P < 0.001) and to have sustained their injuries while barefoot (P < 0.006). CONCLUSIONS: Puncture wounds in diabetic subjects were commonly associated with polymicrobial infections. Pseudomonas was the most common cause of nondiabetic osteomyelitis. These results have implications for differential emergent and chronic treatment of puncture wounds in diabetic versus nondiabetic subjects.

Adult↗
PubMed1995

Caring through activities.

Home care patients require help with health-related activities, but they also want to engage in activities that they like to do, such as reminiscing or listening to music. Home care professionals can improve the lives of their patients by integrating some special activities into daily caregiving activities and teaching these activities to informal caregivers.

Activities of Daily Living↗
PubMed1995

Total-contact casting, sandals, and insoles. Construction and applications in a total foot-care program.

It must be stressed that these tools do not exist in a vacuum and that no single tool is particularly useful unless it is a part of a comprehensive, lifelong foot-care program. A partnership between the health care provider and the patient is essential in making any of these techniques useful. On the positive side, a program incorporating these techniques can be very successful with even the most difficult population. The very successful Parkland Memorial Hospital program provides care for a county hospital population that is often difficult in terms of compliance. Without question, the reasons for incorporating such a program in a public facility are sound. Amputations are avoided; and patients remain or become more functional, thus decreasing hospital cost and patient morbidity and mortality and increasing the patient's potential for contributing to society. Similarly, in private facilities, once the program is established, costs need not run high and considerable amounts can be saved by helping heal and/or prevent the horrendous sequelae of diabetic neuropathies.

Biomechanical Phenomena↗
PubMed1995

Characterization of IHNV isolates associated with neurotropism.

Rainbow trout with a 'neurotropic' form of infectious hematopoietic necrosis (IHN) exhibited behavioral abnormalities and had high virus concentrations localized in brain tissue. Fish with 'hematopoietic' IHN exhibited typical disease signs with the highest concentrations of virus detected in kidney-spleen tissue. Infectious hematopoietic necrosis virus (IHNV) isolates obtained from brain or kidney-spleen tissue were tested for serological relatedness and virulence and pathogenicity differences in 2 sizes of rainbow trout. No major differences were detected by indirect fluorescence tests. Serum neutralization profiles showed 2 predominant patterns that differed dependent upon tissue of origin. However, virulence and pathogenicity differences were not evident.

Animals↗
PubMed1994

Clinical pharmacology of hepatic arterial infusions of 5-bromo-2'-deoxyuridine.

This investigation was undertaken to determine the pharmacokinetic parameters relevant to hepatic arterial (HA) infusion of 5-bromo-2'-deoxyuridine (BrdUrd) and to ascertain the maximum tolerated dose and related toxicities of BrdUrd administered as a 14-day HA infusion. In the pharmacokinetic study, 6 patients received a 2-h i.v. infusion (to steady-state) of BrdUrd at each of 5 escalating dose rates (10 to 160 mg/kg/day) with simultaneous blood sampling for BrdUrd levels from HA and hepatic venous catheters. Dose dependent HA and hepatic venous drug levels, total body clearance, hepatic extraction, and estimated regional exposure advantage were determined. The total body clearance of BrdUrd was high and dose rate dependent, falling from 3340 ml/min with a 10-mg/kg/day infusion to 2180 ml/min at a 160-mg/kg/day dose rate. Hepatic extraction was high and dose rate dependent as well, declining from 80% extraction at 10 mg/kg/day to 68% at 160 mg/kg/day. The calculated estimate for the exposure advantage achievable with HA as compared with i.v. infusion reflects the dose rate dependence of total body clearance and hepatic extraction and decreases from a 70-fold advantage at 10 mg/kg/day to a 30-fold advantage at 160 mg/kg/day. In the Phase I study aimed at determining the maximum tolerated dose, successive groups of 3 patients were administered continuous HA infusions for 14 days at escalated BrdUrd dose rates (5, 10, 15, 25, and 35 mg/kg/day) in order to ascertain dose-limiting toxicity. The maximum tolerated dose of BrdUrd for a 14-day continuous HA infusion was found to be 35 mg/kg/day with reversible thrombocytopenia as the sole dose-limiting toxicity. Skin and other toxicities were infrequent, minor, reversible, and non-dose dependent. No hepatic toxicity was detected despite direct drug infusion into the liver. The high total body clearance and hepatic extraction of BrdUrd substantiate its administration via the hepatic artery as a means to achieve higher exposure with intrahepatic tumors than can be obtained by systemic administration. Despite higher hepatic exposures, no hepatic toxicity was noted, and readily reversible systemic toxicity (thrombocytopenia) was dose limiting for the 14-day continuous HA infusion. Thus, HA infusion of the potent radiosensitizer BrdUrd is both pharmacokinetically rational and well tolerated.

Adult↗