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Biomedical subjects

S H Thomas

Publications and source records attributed to S H Thomas.

At least 109 records · Page 6Linked to original sources
PubMed1989

Diurnal variation in TSH and free thyroid hormones in patients on thyroxine replacement.

Eleven patients with treated hypothyroidism were investigated to examine the effects of time on their thyroid function tests. Each patient was clinically and biochemically euthyroid on once daily thyroxine replacement therapy, taken in the morning. TSH followed a diurnal rhythm with a peak level at 23.30 h and a trough level at 14.30 h. Four subjects had TSH trough levels within the normal range, but with peak levels outside this range. FT4 and FT3 levels fell from their highest levels some three hours after ingestion to the lowest levels just prior to the next dose. This study shows that there are significant time-related variabilities in TSH and thyroid hormone levels in treated hypothyroid patients. This should be taken into account when interpreting results of their thyroid function tests.

Aged↗
PubMed1988

Aerosol deposition in the human lung: effect of high-frequency oscillation on the deposition characteristics of an inhaled nebulized aerosol.

1. Oral high-frequency oscillation (OHFO) may have important effects on aerosol deposition in the lungs. In order to investigate these, a technique was devised to measure regional deposition rates of a nebulized radiolabelled aerosol in the lungs during normal tidal breathing. 2. The effect of three frequencies of OHFO on pulmonary aerosol deposition rate (PADR) in four normal subjects and five patients with chronic airways obstruction (CAO) were assessed using the technique. 3. In separate experiments employing three normal subjects, the effect of OHFO was studied on the deposition rate of aerosol on the oropharynx and delivery apparatus, and on the amount and characteristics of aerosol inhaled by the subjects. 4. Total PADR was significantly reduced by OHFO at 8 Hz and 16 Hz in the normal subjects, and by all three frequencies of OHFO in the CAO patients. In the normal subjects, the regional distribution of aerosol deposition was unchanged, but in the CAO patients a larger proportion of total aerosol deposition occurred in peripheral lung. 5. OHFO reduced the oropharyngeal aerosol deposition rate, increased the loss of aerosol to the atmosphere before inhalation, and increased the deposition of aerosol on the delivery apparatus. The end result was a reduction in the amount of aerosol inhaled, and in the particle sizes measured at the mouthpiece. 6. We conclude that OHFO reduces the amount of aerosol inhaled, but may improve peripheral deposition of inhaled aerosol in patients with CAO. This effect may be of value in the clinical administration of nebulized drugs.

Aerosols↗
PubMed1987

Cyanotic tetralogy of Fallot in a 77 year old man.

We report the clinical details of a 77 year old man with classical tetralogy of Fallot. The patient had clubbing and cyanosis at birth, and exertional squatting in childhood. He was asymptomatic as an adult until the seventh decade, when he developed biventricular failure and had an episode of bacterial endocarditis. He finally died of cerebral infarction and bronchopneumonia following abdominal surgery. In spite of investigations, the diagnosis was not made in life, but only discovered at post-mortem. A persistent ductus arteriosus was also found. Increased pulmonary blood flow via the ductus is believed to have facilitated this patient's unusual longevity.

Aged↗
PubMed1983

Quantitative thin layer chromatographic multi-sulfonamide screening procedure.

In-situ optical scanning of fluorescamine derivatives on thin layer silica gel plates provides a rapid method for the determination of multiple sulfonamides at levels below 0.1 ppm. Sample preparation is minimal. Homogenized liver or muscle is extracted with ethyl acetate and then back-extracted into 0.2M glycine buffer. After pH adjustment, the extract is washed with hexane and extracted with methylene chloride. The organic phase is evaporated to dryness and reconstituted in methanol. Pre-adsorbent layer silica gel plates are used for chromatography. The method has been applied to residues of sulfamethazine, sulfadimethoxine, sulfathiazole, sulfaquinoxaline, and sulfabromomethazine in cattle, swine, turkey, and duck tissues.

Animals↗
PubMed1979

Insulin action on adipocytes. Evidence that the anti-lipolytic and lipogenic effects of insulin are mediated by the same receptor.

1. The dose-response relationships of insulin stimulation of lipogenesis and inhibition of lipolysis were studied simultaneously by using rat adipocytes to determine whether these different effects of insulin are mediated through the same or different sets of receptors. 2. The sensitivity (defined as the concentration of insulin required to produce a half-maximal effect) of the stimulated lipogenic response to insulin was not significantly different from the sensitivity of the anti-lipolytic response to insulin. The addition of different adrenaline and glucose concentrations did not alter the half-maximal concentration of insulin required to inhibit lipolysis. 3. The specificities of the lipogenic and antilipolytic responses were studied by using insulin analogues. The sensitivities of the lipogenic and anti-lipolytic responses were the same for five chemically modified insulins and hagfish insulin, which have potencies compared with bovine insulin of between 3 and 90%. 4. Starving rats for 48h significantly increased the sensitivities of both the antilipolytic and lipogenic responses to insulin, but the changes in the sensitivities of both lipogenesis and anti-lipolysis returned to that of fed rats. 5. We conclude that insulin stimulates lipogenesis and inhibits lipolysis over the same concentration range. These observations provide powerful evidence that the different effects of insulin are mediated through the same set of receptors.

Adipose Tissue↗
PubMedDate not supplied

Thrombolytic therapy in review.

The use of thrombolytic agents for both coronary and noncoronary indications is a rapidly progressing field. There has been substantial debate over which disease processes ultimately benefit from the use of thrombolytic agents. In addition, many recent studies have focused on comparing different thrombolytic agents and dosing regimens in an attempt to gain optimal therapeutic benefit with minimal risk. This paper discusses the current status of thrombolytic therapy for coronary artery disease, pulmonary embolus, peripheral vascular thrombosis, and cerebrovascular infarction.

Cerebrovascular Disorders↗
PubMedDate not supplied

Emergency department treatment of migraine, tension, and mixed-type headache.

The complaint of headache is frequently encountered in the emergency department, but most patients with cephalalgia have a benign etiology for their pain. At least 90% of patients presenting with headache are diagnosed as suffering from benign vascular or muscle-tension (for example, migraine, tension, or mixed-type) headache. There is no consensus on the ideal therapeutic approach to these patients. Classically utilized narcotic therapy suffers from problems with efficacy, relapse, and potential for abuse and addiction. However, other agents have successively proved to be imperfect as well, despite the many therapeutic approaches that have been suggested in the medical literature. While no one drug has emerged as clearly superior for treatment of acute benign headache, recent investigations have clarified the role of certain therapies. This review is intended to familiarize emergency physicians with the latest information on most recommended therapeutic approaches to the patient with headache.

Analgesics↗
PubMedDate not supplied

The effectiveness of esophageal stethoscopy in a simulated in-flight setting.

PURPOSE: Previous research has confirmed the inability of flight nurses in an airborne BO-105 helicopter to hear breath sounds using normal or amplified transthoracic stethoscopy. The purpose of this study was to determine whether esophageal stethoscopy enabled effective auscultation of breath sounds in a simulated in-flight environment. METHODS: The cabin-sound environment of an in-flight BO-105 was recorded and recreated in an audiology laboratory, where five flight nurses were evaluated listening to taped breath sounds via an esophageal stethoscope. This audiotape model, validated in a previously published study, used a tape consisting of 24 20-second segments. Each segment, the beginning of which was marked with a beep signal, consisted of 20 seconds of silence or breath sounds. The distal (esophageal) end of the esophageal stethoscope was attached to the tape recorder; the intensity level of breath sounds heard at the stethoscope earpiece was calibrated to equate the sound level of actual esophageal breath sounds recorded on a volunteer. RESULTS: All nurses correctly identified the 24 taped segments as silent or including breath sounds 100% of the time. CONCLUSION: In the simulated environment tested, esophageal stethoscopy enabled 100% accuracy in identification of breath sounds, as compared with previously reported 0% efficacy for standard transthoracic auscultation. Study in the actual patient-care environment is indicated to confirm the usefulness of esophageal stethoscopy in the in-flight setting.

Air Ambulances↗
PubMedDate not supplied

Elderly patients with closed head trauma after a fall: mechanisms and outcomes.

Falls in the elderly leading to closed head trauma represent a significant cause of morbidity and mortality in that population, but are not well-characterized. The purpose of this study was to determine the mechanism of fall, outcome, and additional risk factors in elderly patients who require cranial computed tomography (CT) scan after a fall. We conducted a retrospective case series of patients age 60 years and older with closed head trauma secondary to falling who underwent CT scan in the emergency department (ED). Data were gathered from ED and hospital records. The setting was an urban Level I trauma center. Our series consisted of 189 patients, of whom 31 (16%) had an abnormal head CT scan and four (2%) required neurosurgery. Cerebral contusions (38%) and subdural hematomas (33%) were the most common lesions seen on CT scan. Falls from standing (76%) were more common than falls on stairs (19%) or from height (5%), but the latter two were more likely to result in an abnormal CT scan (stairs 42%, height 40%). An abnormal neurologic examination was associated with a higher risk of the need for neurosurgery (risk ratio 11.5). We conclude that among elderly patients who fall and present to an ED with evidence of closed head trauma, a significant percentage will have abnormal CT scans but only a small minority will require neurosurgery. While falls from standing are more common, falls on stairs or from height are associated with a higher risk of having an abnormal CT scan. A focal neurologic examination is a strong predictor of the need for neurosurgical intervention.

Accidental Falls↗
PubMedDate not supplied

Red cabin lights impair air medical crew performance of color-dependent tasks.

INTRODUCTION: Red cabin lighting is often used for nighttime patient transports in helicopters. This study was conducted to determine if red lighting results in impairment of color-dependent tasks. METHODS: An emergency medical services pilot adjusted red lighting in a BO-105 cabin to maximum acceptable intensity. Thirteen emergency room residents were shown positive and negative CO2 detectors and skin-colored and cyan-tinted rubber masks; percentages of correctly identified masks and detectors were noted. Subjects also read drug name and amount from 12 medication labels. Wilcoxon analysis (p = 0.05) was used to compare label reading accuracy between two groups: control (black/white lettering/background) and red (red lettering or background). RESULTS: Percentages of accurately identified masks and detectors in the red light setting were as follows: normal mask 61.5%, cyanotic mask 30.8%, negative and positive CO2 detectors 46.2%. Ability to correctly read medication labeling was significantly (p = 0.003) greater in control (76.9 +/- 10.9%) as compared to red groups (16.3 +/- 13.4%). CONCLUSION: Red cabin lighting appears to impair performance of certain critical tasks requiring color discernment. Consideration of this by medical crews working under red light conditions could reduce risk for patient-care errors.

Air Ambulances↗
PubMedDate not supplied

Cabin configuration and prolonged oral endotracheal intubation in the AS365N2 Dauphin EMS helicopter.

INTRODUCTION: Most patients transported by air who require endotracheal intubation undergo endotracheal intubation before transport. However, in-flight endotracheal intubation may be indicated in the setting of certain scene conditions, in-flight patient deterioration, or endotracheal tube dislodgement. A previous report of high endotracheal intubation efficacy in the BK-117 in-flight recommended that flight programs review endotracheal intubation capabilities in their own aircraft. This study was conducted to determine whether in-aircraft endotracheal intubation times in the AS365N2 Dauphin were comparable to those previously reported for the BK-117. SETTING: AS365N2 and BK-117 helicopters stationary on a helipad. METHODS: Eight flight team members per formed three mannequin endotracheal intubations in each aircraft. Three time intervals were assessed: Setup, time required for equipping and positioning for endotracheal intubation; placement, time from laryngoscopy to endotracheal intubation; and total (Setup + Placement). Mean times for the BK-117 and AS365N2 were compared using the t test (a=0.05). RESULTS: All endotracheal intubation attempts were successful, but setup (p=0.0001), placement (p=0.0271), and total (p=0.0011) times were longer in the Dauphin. Crew members unanimously expressed endotracheal intubation difficulty caused by positioning problems in the Dauphin. CONCLUSION: In-aircraft intubation is significantly more time-consuming in the Dauphin than in the BK-117. This prolongation of intubation appears to be due to problems with positioning of the air medical crew and patient.

Air Ambulances↗
PubMedDate not supplied

Reduced emergency department stabilization time before cranial computed tomography in patients undergoing air medical transport.

INTRODUCTION: Advanced patient stabilization skills provided by air medical providers were hypothesized to result in streamlined emergency department (ED) stabilization of patients with head injuries requiring urgent cranial computed tomography (CCT). The goal of this study was to compare initial ED stabilization times between air- and ground-transported patients requiring urgent CCT and emergency neurosurgical hematoma evacuation. SETTING: Academic Level trauma center (annual ED census 60,000) receiving patients from ground EMS and a nurse/paramedic air medical transport team. METHODS: This retrospective study identified, from a database of 15 months of ED visits, consecutive group of adults who had CCT performed within 60 minutes of ED arrival and underwent emergent craniotomy for intracranial hematoma. Demographics, hemodynamic status, patient acuity, and time intervals between ED and CCT suite arrivals were compared between air and ground patients using chi-square, Fisher's exact, and t-tests (p = 0.05). RESULTS: Eleven air- and 39 ground-transported patients were eligible. All patient acuity data were similar between groups. Air patients were more likely to be intubated (100% versus 71.8%, p = .04) and had shorter mean ED stabilization times (29 versus 40 minutes, p = .02) than the ground. CONCLUSION: This study suggests that advanced patient stabilization offered by air medical transport may result in reduced ED stabilization time for patients requiring urgent craniotomy.

Academic Medical Centers↗
PubMedDate not supplied

Analysis of patients discharged from receiving hospitals within 24 hours of air medical transport.

INTRODUCTION: Use review has become increasingly important in the current atmosphere of cost justification for air medical transport. One criterion for use review is patient discharge from receiving hospitals within 24 hours of transport. The objective of this study was to determine the frequency and characteristics of patients discharged within 24 hours of air transport; the goal was to identify particular patient types likely to be discharged soon after air transport. METHODS: Flight records from November 1994 to September 1995 were reviewed. Follow-up identified patients who were discharged within 24 hours of air medical transport; these were designated the "24-hour group." Other patients were designated the "overall group." Comparisons between groups were made using the t test, Wilcoxon rank sum, and chi-square analysis (alpha = 0.05) for the following factors: age, vital signs, Glasgow coma score, percentage of intubated patients, and percentage of trauma and scene transports. RESULTS: Of the 945 flights analyzed, 42 (4.4%) transported patients who were discharged within 24 hours of air transport. Patients in the 24-hour group were younger, less likely to be intubated, and more likely to be scene-trauma transports compared with the overall group. CONCLUSION: This study demonstrates that air medical transports meet currently accepted criteria for helicopter transport. This study suggests that inappropriate air medical transport is rare, even in patients discharged from receiving hospitals within 24 hours of air transport.

Air Ambulances↗