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Biomedical subjects

S H Thomas

Publications and source records attributed to S H Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1994

Effect of an in-flight helicopter environment on the performance of ALS interventions.

INTRODUCTION: Patients transported by air ambulance are often critically ill and, thus, have a relatively high likelihood of requiring advanced life support (ALS) measures during transport. Despite this fact, the ability of the air medical crew to perform ALS interventions efficiently while in flight has not been investigated. SETTING: The study was conducted with BO 105 and BK 117 helicopters and a ground transport unit at a university hospital-based air ambulance service. METHODS: Ten flight nurses were timed performing various ALS tasks while in flight in each aircraft and in the ground ambulance. Mean times for performance of each task in the aircraft and in the ground unit were analyzed using Dunnett's method for analysis of multiple means; alpha was set at 0.01. RESULTS: Times required to perform all ALS tasks were significantly increased in the BO 105 setting compared to the setting of the BK 117 or the ground ambulance (p < 0.01). Times for performance of interventions in the BK 117 did not differ significantly from corresponding times in the ground setting. CONCLUSION: It appears that the environment of the BO 105 may impose limitations on the timely performance of certain ALS interventions.

Air Ambulances↗
PubMed1994

Controlled trial of an intravenous fluid warmer.

INTRODUCTION: In critically ill patients (e.g., trauma victims) prevention of hypothermia is an important goal. Infusion of warm fluids has been addressed in the hospital setting, but not in the air medical transport setting. PURPOSE: The purpose of this study was to test the efficacy of an intravenous (IV) fluid warming device that is well-suited for the air medical transport environment. METHOD: The warmer studied was used with IV fluid heated to approximately 38 degrees C (100 degrees F) and evaluated in environmental temperatures of -16 degrees C (3 degrees F), 2 degrees C (36 degrees F), and 22 degrees C (72 degrees F). The warmer group was compared to a control group of similarly treated IV fluids without a warming device. Temperatures were measured at baseline, 15, 30 and 60 minutes. RESULTS: The 30- and 60-minute fluid temperatures were higher in the warmer than in the control group for all three environmental temperature settings. At 15 minutes, fluid temperatures were higher in the warmer group for the 2 degrees C and -16 degrees C, but not the 22 degrees C, environments. There was no significant drop in temperature in the warmer group in the 22 degrees C and 2 degrees C settings, but a decrease was noted in the -16 degrees C environment. There was a significant drop in the control group at all temperatures tested. CONCLUSION: The IV fluid warmer tested effectively maintains the temperature of warmed IV fluids in temperatures above 2 degrees C. At -16 degrees C there was significant heat loss, but the loss was significantly less when compared to the control group.

Air Ambulances↗
PubMed1994

Interhospital transfer of cardiac patients: does air transport make a difference?

INTRODUCTION: The purpose of this study was to compare the outcome of interhospital transported cardiac patients for whom bias in selecting transport mode was removed due to helicopter unavailability. METHODS: Patients with the diagnosis of unstable angina or myocardial infarction who underwent transport by ground only because helicopter transport was not available, were compared to patients transported by helicopter. Patients were matched by gender and referring hospital. Ninety-six patients were studied and both groups were comparable in age, diagnosis, Killip classification, treatment with thrombolytics and post-transport procedures. RESULTS: There were no statistically significant differences between the groups for mean ICU days (5.3 air vs. 3.5 ground) and mean hospital days (9.9 vs. 8.2, respectively). No differences were detected in the proportions of deaths within 72 hours of arriving at the receiving institution (1/48 air vs. 0/48 ground), but air transportation was associated with more total deaths (9/48 vs. 1/48, respectively). CONCLUSION: It appears that the interhospital transport of cardiac patients by air offers no outcome advantage over ground transport.

Air Ambulances↗
PubMed1994

A review of drug use during air medical transport to optimize an air ambulance formulary.

INTRODUCTION: The advent of air medical transport has pushed the delivery of critical care medicine into the prehospital arena. As a result, a wide variety of pharmacologic agents must be available in the air medical setting. PURPOSE: The purpose of this study was to conduct a retrospective review of drugs used during air medical transport to allow a streamlining of the air ambulance formulary. METHODS: All flights completed since the inception of the study's helicopter air ambulance program in 1985 through September 1991 were analyzed to determine which medications were used in flight. Drugs were counted if they were administered while in flight for either a scene or interhospital transport. RESULTS: Review of 2,694 flights showed that 45 individual drugs had been routinely carried during the study period. Many of these agents were administered fewer than five times during the six years, and 10 drugs were not used at all. CONCLUSION: As a result of this investigation, the formulary for our air medical transport service was modified. The authors recommend similar critical audits of drugs carried in flight be performed by other air ambulance services.

Air Ambulances↗
PubMed1994

Is oral endotracheal intubation efficacy impaired in the helicopter environment?

INTRODUCTION: Patients transported by helicopter often require advanced airway management. The purpose of this study was to determine whether or not the in-flight environment of air medical transport in a BO-105 helicopter impairs the ability of flight nurses to perform oral endotracheal intubation. SETTING: The study was conducted in an MBB BO-105 helicopter. METHODS: Flight nurses performed three manikin intubations in each of the two study environments: on an emergency department stretcher and in-flight in the BO-105 helicopter. RESULTS: The mean time required for in-flight intubation (25.9 +/- 10.9 seconds) was significantly longer than the corresponding time (13.2 +/- 2.8 seconds) required for intubation in the control setting (ANOVA, F = 38.7, p < .001). All intubations performed in the control setting were placed correctly in the trachea; there were two (6.7%) esophageal intubations in the in-flight setting. The difference in appropriate endotracheal intubation between the two settings was not significant (chi 2 = 0.3; p > 0.05). CONCLUSION: Oral endotracheal intubation in the in-flight setting of the BO-105 helicopter takes approximately twice as long as intubation in a ground setting. The results support pre-flight intubation of patients who appear likely to require urgent intubation during air medical transport in the BO-105 helicopter.

Air Ambulances↗
PubMed1994

Accuracy of fingerstick glucose determination in patients receiving CPR.

Recent demonstration of the dangers of hyperglycemia in the setting of cerebral hypoperfusion has resulted in recommendations to abandon the long-standing practice of empiric administration of dextrose to patients with altered mental status. Patients receiving basic cardiopulmonary resuscitation (CPR) have been identified as being at particular risk from inappropriate administration of dextrose. We conducted a prospective trial to determine whether the blood glucose of 50 patients receiving CPR could be accurately assessed using a portable rapid-reagent device in the emergency department (ED). We analyzed both capillary and venous blood samples in the rapid-reagent system, using laboratory analysis of venous blood to define the patient's true blood glucose level. Capillary blood analysis identified 8 patients as hypoglycemic; only 3 of these patients were truly hypoglycemic, and 2 patients identified as hypoglycemic by fingerstick were actually hyperglycemic on laboratory analysis. The only instance in which a patient was classified differently by venous rapid-reagent and laboratory analysis occurred when a patient assessed as normoglycemic (169 mg/dL) by the laboratory had a venous rapid-reagent glucose reading of 182 mg/dL (hyperglycemic). We recommend that venous (rather than capillary) blood be used to analyze blood glucose in all patients receiving CPR before dextrose administration is considered.

Adult↗
PubMed1994

Upper airway obstruction from tonsillar infection in adults.

We report the case of a 23-year-old male who presented to the emergency department with severe upper airway obstruction resulting from infection of the palatine tonsils. Manifestations of tonsillar infection and airway obstruction included hoarseness and extreme difficulty breathing, severe sore throat and inability to swallow liquids or solids. Urgent otolaryngologic consultation was obtained, and the patient was taken directly to the operating suite for nasotracheal intubation with tracheostomy standby. The patient was maintained on broad-spectrum antibiotics and was discharged after a hospital course complicated by pulmonary oedema, tracheitis and difficulty weaning from the ventilator, requiring temporary tracheostomy. The Monospot test was negative for infection with the Epstein-Barr virus (EBV). We could find no previously reported cases of adults with severe palatine tonsillar-induced airway obstruction which was not due to infection with EBV (mononucleosis). The airway management of obstruction due to palatine tonsillar hypertrophy is discussed.

Adult↗
PubMed1993

Therapeutic aerosols in children.

The use and variety of drugs administered to children as inhaled aerosols is increasing, but little is known about how much drug reaches the lung and how it is distributed there in different age groups. In this article the reasons for measuring aerosol deposition in children are discussed and the potential methods for doing this described. Of the methods available, only the use of radiolabelled aerosols gives accurate information on total lung deposition and distribution. The potential risk of the radiation exposure required for these measurements varies with the age of the child but seems to be small. Properly designed studies are expected to clarify the factors affecting lung deposition in children and identify methods of inhalation associated with efficient and predictable delivery of the drug. Measurements of radioaerosol deposition may therefore be justified in children when this information is expected to lead to improvements in the effectiveness or safety of their treatment.

Administration, Inhalation↗
PubMed1993

The influence of steady-state ciprofloxacin on the pharmacokinetics and pharmacodynamics of a single dose of diazepam in healthy volunteers.

The effects of pretreatment with a seven day course of ciprofloxacin on pharmacokinetics and pharmacodynamics of an intravenous (5 mg) dose of diazepam were investigated in a group of 12 healthy volunteers in a double-blind placebo-controlled crossover study. Ciprofloxacin pretreatment significantly reduced diazepam CL (without ciprofloxacin: 19.5 ml.h-1 kg-1; with ciprofloxacin: 12.3 ml.h-1 kg-1). Diazepam t1/2 was also prolonged (without ciprofloxacin: 36.7 h; with ciprofloxacin: 71.1 h), but volume of distribution was unaltered (without ciprofloxacin: 1.1 l.kg-1; with ciprofloxacin: 1.1 l.kg-1). However, no significant changes were detected in psychometric tests of digit symbol substitution, tapping rate and short memory, as well as levels of concentration, vigilance and tension measured by visual analogue scales.

Adult↗
PubMed1993

Paracetamol (acetaminophen) poisoning.

Paracetamol poisoning caused by intentional overdose remains a common cause of morbidity. In this article the mechanism of toxicity and the clinical effects and treatment of poisoning, including specific antidotal therapy, are reviewed. Areas for further research directed at reducing morbidity and mortality from paracetamol poisoning are considered.

Acetaminophen↗
PubMed1993

Impedance cardiography during exercise in patients with coronary heart disease.

Impedance cardiography may be a simple way of assessing left ventricular performance during exercise. Measurements were therefore made during exercise testing in 102 consecutive male patients with suspected coronary disease prior to cardiac catheterization. These were subsequently divided into four groups: group A, normal; group B, 1- or 2-vessel disease; group C, 3-vessel disease (groups A, B, and C, left ventricular ejection fraction (LVEF) > 55%); and group D, 3-vessel disease with LVEF < 55%. Immediately after peak exercise several impedance measures were significantly correlated with resting LVEF, especially dZ/dtmax (R = 0.41, P < 0.001) and Heather index (R = 0.46, P < 0.001). Heather index was the best discriminator between the disease groups with mean values (95% confidence intervals) of 25.7 (22.2-29.2) (group A), 21.9 (20.6-23.2) (group B), 18.4 (16.2-20.6) (group C), and 15.3 (10.3-20.3) omega s-2 (group D) but there was considerable overlap between groups (risk ratios 1.17 and 3.15 for any and triple-vessel coronary disease respectively). Measurements were therefore of little diagnostic value. The majority of patients with abnormal responses could be identified more simply by their poor exercise tolerance or abnormal blood pressure response.

Adult↗
PubMed1993

Disposition of nebulized pentamidine measured using the direct radiolabel 123I-iodopentamidine.

The pulmonary deposition of nebulized pentamidine (300 mg, Respirgard II nebulizer) was measured in seven human immunodeficiency virus (HIV)-positive men using a new radiopharmaceutical, 123I-iodopentamidine. Mean total pulmonary deposition was 15.3 mg or 5.1% of the initial nebulizer dose. Further studies in two of the patients showed that at 24 h, 87% of deposited 123I was retained in the lungs. Small amounts of activity (expressed as a percentage of the initial nebulizer activity) were also detected over the thyroid (0.4%), bladder (1%) and gut (0.7%). The ratio of 123I activity to pentamidine concentration was similar in the nebulizer solution and urine. These results suggest that 123I-pentamidine may be sufficiently stable in vivo to be used to study the biodistribution of inhaled and parenteral pentamidine in humans.

Administration, Inhalation↗
PubMed1993

Paracetamol elimination in patients with non-insulin dependent diabetes mellitus.

The pharmacokinetics and metabolism of an intravenous dose (500 mg) of paracetamol were studied in a group of non-insulin dependent diabetic patients (n = 10) and in a group of healthy control subjects (n = 9). Paracetamol clearance, half-life and the partial clearance to paracetamol glucuronide were not significantly different, but the partial clearance to paracetamol sulphate was significantly reduced (62 +/- 18 vs 86 +/- 17 ml h-1 kg-1 (mean +/- s.d.)) and the renal clearance of paracetamol was significantly increased (56 +/- 20 vs 22 +/- 6 ml h-1 kg-1 (mean +/- s.d.)) in the non-insulin dependent diabetic patients, compared with the control group.

Acetaminophen↗
PubMed1993

Pulmonary deposition of a nebulised aerosol during mechanical ventilation.

BACKGROUND: There is increasing use of therapeutic aerosols in patients undergoing mechanical ventilation. Few studies have measured aerosol delivery to the lungs under these conditions with adequate experimental methods. Hence this study was performed to measure pulmonary aerosol deposition and to determine the reproducibility of the method of measurement during mechanical ventilation. METHODS: Nine male patients were studied during mechanical ventilation after open heart surgery and two experiments were performed in each to determine the reproducibility of the method. A solution of technetium-99m labelled human serum albumin (99mTc HSA (50 micrograms); activity in experiment 1, 74 MBq; in experiment 2, 185 MBq) in 3 ml saline was administered with a Siemens Servo 945 nebuliser system (high setting) and a System 22 Acorn nebuliser unit. Pulmonary deposition was quantified by means of a gamma camera and corrections derived from lung phantom studies. RESULTS: Pulmonary aerosol deposition was completed in 22 (SD 4) minutes. Total pulmonary deposition (% nebuliser dose (SD)) was 2.2 (0.8)% with 1.5% and 0.7% depositing in the right and left lungs respectively; 0.9% of the nebuliser activity was detected in the endotracheal tube or trachea and 51% was retained within the nebuliser unit. Considerable variability between subjects was found for total deposition (coefficient of variation (CV) 46%), but within subject reproducibility was good (CV 15%). CONCLUSIONS: Administration of aerosol in this way is inefficient and further research is needed to find more effective alternatives in patients who require mechanical respiratory support. This method of measurement seems suitable for the assessment of new methods of aerosol delivery in these patients.

Administration, Inhalation↗
PubMed1993

Lung deposition of nebulised pentamidine in children.

BACKGROUND: Nebulised pentamidine is effective for preventing Pneumocystis carinii pneumonia in adults with acquired immunodeficiency syndrome. The nebuliser dose required to produce equivalent lung concentrations of pentamidine in children is unknown. This study was performed to measure pulmonary pentamidine deposition in children and to relate this to age, ventilation pattern, and body size. METHODS: Nebulised pentamidine (50 mg in 6 ml saline) was administered to 12 children (including one with lymphocytic interstitial pneumonitis) and to six adults with human immunodeficiency virus infection using a Respirgard II nebuliser. Technetium-99m labeled colloidal human serum albumin was used as an indirect marker for pentamidine and deposition in the lungs was detected by a gamma camera. RESULTS: Absolute deposition of pentamidine was not related to age, height, weight, spirometry, or ventilation characteristics. Deposition, as a mean (SD) percentage of nebuliser output, was similar in children aged 8-11 years (5.5(2.4)%), teenagers aged 12-15 years (7.2(2.2)%) and adults (7.1(2.6)%). Aerosol concentration within the lungs (% nebuliser output deposited/predicted total lung capacity) was therefore higher in children (1.9(1.5)%/1) and teenagers (1.9(0.7)%/1) than in adults (1.0(0.7%)/1), and was negatively correlated with height (r = -0.69) and weight (r = -0.50). Deposition of aerosol in the region of the large central airways was particularly marked in children. Small reductions in forced expiratory volume in one second and forced vital capacity after treatment did not differ significantly between adults and children and visual analogue scores of subjective adverse effects did not vary with age. CONCLUSIONS: These results suggest that children probably require lower nebuliser pentamidine doses to produce lung pentamidine concentrations equivalent to those found to be effective for preventing P carinii pneumonia in adults using the Respirgard II nebuliser.

Acquired Immunodeficiency Syndrome↗