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Biomedical subjects

S H Thomas

Publications and source records attributed to S H Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1996

Rate of patient workups by non-emergency medicine residents in an academic emergency department.

OBJECTIVE: To quantify the number of patients seen per hour by non-emergency medicine (non-EM) residents in a university hospital ED. METHODS: This retrospective observational study was performed in a university hospital ED and level I trauma center. The facility had no EM residency, but was staffed with 24-hour EM faculty coverage. A computerized tracking system was searched for the number of patients seen by each of 93 non-EM residents for 12 nonconsecutive months. The ED schedule for each month was used to calculate the number of hours worked by each resident. From these figures, the number of patients seen per hour by each resident was calculated. RESULTS: The postgraduate years of training of the residents were as follows: 78 (84%) were PGY1, ten (11%) were PGY2, and five (5%) were PGY3. All the residents combined saw a mean 0.95 +/- 0.20 patients/hour, with a range from 0.58 to 1.75 patients/hour. There was no significant difference between the numbers of patients seen when compared by specialty using the Tukey-Kramer test (alpha = 0.05). CONCLUSION: The rate at which non-EM residents work up patients is consistent with previously reported rates for EM residents.

Education, Medical, Graduate↗
PubMed1996

Amrinone as an antidote in experimental verapamil overdose.

OBJECTIVE: To evaluate the effect of amrinone as a treatment for the hemodynamic effects of verapamil overdose in a canine model. METHODS: This nonblind interventional study was performed in an established canine model of verapamil toxicity, without concurrent control animals. Pentobarbital-anesthetized and instrumented dogs (n = 8) were maintained and observed for 60 minutes or until death. The animals were overdosed with verapamil, 15 mg/ kg IV, over 30 minutes. Hemodynamic parameters, including cardiac index (CI), heart rate (HR), and mean arterial pressure (MAP), were monitored. Completion of the verapamil infusion represented the defined point of toxicity; at that point, all the animals received an amrinone bolus of 2 mg/kg IV over 2 minutes followed by an amrinone drip at 10 micrograms/kg/min. The hemodynamic values at the defined point of toxicity were compared with those obtained postinitiation of the amrinone infusion. RESULTS: Two animals died before the 60-minute observation period elapsed. Baseline CI was 5.6 L/min/m2. Following verapamil-induced toxicity, mean CI was 2.2 L/min/m2. After administration of amrinone, a significant (p < 0.05) increase in CI was observed at 30 minutes (CI = 3.6 L/min/m2), 45 minutes (CI = 4.2 L/ min/m2), and 60 minutes (CI = 4.2 L/min/m2). There was no statistically significant difference noted for MAP or HR compared with "point of toxicity" values. CONCLUSION: Amrinone appears to reverse the depressed cardiac index associated with verapamil overdose in a canine model while having no significant effect on the hypotension or bradycardia.

Amrinone↗
PubMed1996

Presentation of poisoned patients to accident and emergency departments in the north of England.

1. A 12 week prospective survey of all patients of any age with confirmed or suspected poisoning presenting to six accident and emergency departments in the North East of England was performed to establish the local incidence and patterns of presentation of poisoning. 2. 945 episodes of poisoning involving 852 patients were recorded representing approximately 1.2% of all A&E presentations and suggesting an annual attendance rate of 2.7 per 1000 persons per year. 3. Attendance rates varied threefold between hospitals and were similar in males and females overall; between the ages of five and 14 attendances were more common in females (1.9 vs 0.6/10(3)/y) while between 0 and 4 y (3.1 vs 2.4) and 25 and 34 y (3.9 vs 2.9/10(3)/y) they were more common in males. 4. The median interval between poisoning and presentation was 2 h (mean 4.1 h) and only 19% of cases presented within 1 h. Presentation was most common between Friday evening and Tuesday morning and in the late afternoon and evening. 5. 6% of the patients presented more than once with poisoning during the study period and 37% had a past history of deliberate self-harm. The most common poisons involved were paracetamol (43%), opioids (15%) and benzodiazepines (15%). 6. The study illustrates the frequency of presentations of poisoning to A&E departments. The high rate of poisoning in young men and the increasing use of paracetamol are particular causes for concern.

Acetaminophen↗
PubMed1996

Factors affecting hospital admission and length of stay of poisoned patients in the north east of England.

1. Poisoning is a common reason for presentation to hospital and hospital admission but there is no agreed policy for managing these patients. This study examined the management of patients presenting with poisoning and the factors affecting the probability of hospital admission and prolonged stay. 2. Data on all cases of poisoning presenting to six Accident and Emergency departments in the North East of England over 12 weeks in 1994 was collected prospectively from A&E notes. Length of stay and outcome were recorded from hospital computer records. 3. Overall, 73% of patients were admitted to a medical ward. Probability of admission was not independently affected by age or gender but was increased in those with intentional poisoning (Odds Ratio (OR) 3.3 [95% CI 1.8, 6.1]), a history of self harm (OR 1.7, [1.0, 2.9]) or potentially hazardous poisoning (OR 3.7 [2.1, 6.6]). There were significant variations between hospitals (50-80%) which could not be attributed to case mix. 4. Prolonged stay (> 2 nights) was more common in patients over 65 years (OR 6.8 [2.9, 16.1]), those with intentional poisoning (OR 2.7 [1.1, 6.6]) and those with potentially hazardous poisoning (OR 2.6 [1.4, 4.9]). Mean hospital stay was 1.5 days and varied significantly between hospitals from 0.8 to 2.1 days and this was independent of case mix. 5. There are appreciable variations in the management of poisoning between hospitals which are not explained by patient characteristics. Savings would occur if rates of admission and duration of stay were reduced by those hospitals where admission is more frequent or hospital stay is longer. However, the impact of this on long term morbidity is unknown.

Adolescent↗
PubMed1995

Utilization of a pressure-sensing monitor to improve in-flight chest compressions.

Previous research at the Division of Air Medical Services at East Carolina University School of Medicine has demonstrated impairment of chest compression efficacy in the setting of an airborne BO-105 helicopter. This study was undertaken to determine whether in-flight compression efficacy could be improved with utilization of a pressure-sensing monitor providing real-time feedback during cardiopulmonary resuscitation (CPR). Ten flight nurses each performed two minutes of in-flight chest compressions on a mannequin that electronically assessed compression depth and hand placement. The session was then repeated using the pressure-sensing device. The mean proportion of correct compressions (95.7 +/- 3.2%) achieved with utilization of the pressure-sensing monitor was significantly higher (P < .01) than the corresponding proportion for the control group (33.4 +/- 12.1%). This study demonstrated that the difficulties of performing effective in-flight chest compressions are largely overcome with utilization of a pressure-sensing device providing real-time feedback on compression efficacy.

Aerospace Medicine↗
PubMed1995

Exacerbation of verapamil-induced hyperglycemia with glucagon.

To evaluate the effects of verapamil intoxication and glucagon treatment on blood glucose levels in an intact canine model, 15 mg/kg verapamil was administered intravenously over a 30-minute period to mongrel dogs under pentobarbital anesthesia. Animals in the experimental group subsequently were administered 2.5 mg glucagon followed by an infusion of 2.5 mg per hour; control group animals were administered an equal volume of saline. Blood glucose was assessed before verapamil administration (baseline), and at 10 minutes (time 10) and 60 minutes (time 60) after completion of the verapamil infusion. Glucose values were compared between control and experimental groups using Dunnett's method (P = .05). At baseline, no animals were hyperglycemic and there was no difference in glucose levels. Animals in both groups became hyperglycemic after verapamil infusion. At time 10, the experimental group had significantly higher glucose levels (265 +/- 17.1 mg/dL) than the control group (209 +/- 18.3 mg/dL). By time 60, there was no significant difference between glucose values in the control (262 +/- 31.4) and experimental (246 +/- 24.8) groups. It was concluded that verapamil intoxication consistently resulted in hyperglycemia in this model. Glucagon therapy was associated with an early but nonsustained exacerbation of verapamil-induced hyperglycemia.

Animals↗
PubMed1995

Decay in quality of closed-chest compressions over time.

STUDY OBJECTIVE: To characterize fatigue-induced deterioration in the adequacy of closed-chest compressions performed over a period of 5 minutes and to determine whether CPR providers can recognize the effects of fatigue on compression adequacy. DESIGN: Prospective evaluation of study subjects performing closed-chest compressions on an electronic mannequin that assesses compression placement and depth. SETTING: Major resuscitation room in rural university hospital emergency department. PARTICIPANTS: Eleven experienced nursing assistants who regularly provide CPR in the ED. RESULTS: Each study participant performed 5 minutes of closed-chest compressions. Compression adequacy (for placement and depth) was assessed with the mannequin and reported on an attached monitor out of view of the study subjects. Subjects were asked to verbally indicate the point during their 5-minute compression period at which they felt too fatigued to provide effective compressions (arbitrarily defined as a minimum of 90% of all compressions being judged correct by the mannequin). We used one-way repeated-measures ANOVA and regression analysis to determine whether compression adequacy diminished over time. ANOVA was also used to determine whether the total compressions performed per minute diminished over time. The percentage of correct chest compressions decreased significantly after 1 minute of compressions (P = .0001). We found 92.9% of compressions performed during minute 1 to be correct. The percentages for minutes 2 through 5 were as follows: 67.1%, 39.2%, 31.2%, and 18.0%. Regression analysis revealed a decrement in compression adequacy of 18.6% per minute after the first minute of compressions. The number of total compressions attempted per minute did not decrease (P = .98). Study subjects did not accurately identify the point during their 5-minute sessions at which their fatigue caused compressions to become impaired. Whereas mean compression adequacy declined below 90% after only 1 minute, the time of indicated fatigue was 253 +/- 40 seconds (mean +/- SD). CONCLUSION: Although compression rate was maintained over time, chest compression quality declined significantly over the study period. Because CPR providers could not recognize their inability to provide proper compressions, cardiac arrest team leaders should carefully monitor compression adequacy during CPR to assure maximally effective care for patients receiving CPR.

Analysis of Variance↗
PubMed1995

Effects of inhaled nebulized morphine on ventilation and breathlessness during exercise in healthy man.

1. Nebulized inhaled morphine has been reported to increase exercise endurance in patients with chronic lung disease and to relieve dyspnoea in patients with malignant disease. Potential mechanisms include a central effect occurring after systemic drug absorption or a local action mediated by receptors in the lung. 2. The ventilatory effects of nebulized morphine (10 and 25 mg) were therefore compared with those of intravenous morphine (1.0 and 2.5 mg) and placebo in a double-blind study involving 12 young healthy males. Submaximal cycle ergometry with respiratory gas analysis was performed 15 min after drug administration and breathlessness assessed using a linear visual analogue scale. 3. Neither dose of inhaled morphine had statistically significant effects on spirometry, heart rate, ventilation, respiratory gases or breathlessness at any level of exercise. The slopes and intercepts of the lines relating ventilation to breathlessness were also unaffected. 4. Intravenous morphine 2.5 mg reduced breathlessness slightly at the highest equivalent workload [mean (least significant range) 33 mm (26-40 mm)] compared with placebo [41 mm (34-48 mm), P < 0.05] but had no other significant effects. 5. These results do not support the hypothesis that intrapulmonary opiate receptors modulate the sensation of breathlessness in healthy man. The possibility that inhaled morphine may affect breathlessness caused by other factors, such as disease, has not been excluded.

Administration, Inhalation↗
PubMed1995

Concentration dependent cardiotoxicity of terodiline in patients treated for urinary incontinence.

OBJECTIVE: Terodiline, an antimuscarinic and calcium antagonist drug, was used to treat detrusor instability but was withdrawn in 1991 after provoking serious ventricular arrhythmias associated with increases in the corrected QT interval (QTc). This research was performed to relate drug induced electrocardiographic changes in asymptomatic recipients to plasma concentrations of the R(+) and S(-) terodiline enantiomers. SETTING: Urological and geriatric clinics and wards. SUBJECTS: Asymptomatic patients taking terodiline in stable dose. METHODS: Electrocardiograms (50 mm/s) were collected from patients while they were taking terodiline and compared with ECGs obtained before or after terodiline. QT interval, heart rate corrected QT interval (QTc), and QT dispersion (QTd) were measured. Drug induced electrocardiographic changes were related to plasma concentrations of R(+) and S(-) terodiline. RESULTS: During terodiline treatment mean QTc and QTd were prolonged (491(43) and 84 (35) ms 1/2) compared with measurements made off therapy (443 (33) and 42 (17) ms 1/2, paired t tests, P < 0.002 and P < 0.01 respectively) in the 12 patients in sinus rhythm. The mean (95% confidence interval) drug induced increases were 48 (23 to 74) ms 1/2 for QTc and 42 (13 to 70) ms 1/2 for QTd. These increases correlated with total plasma terodiline (QTc: r = 0.77, P < 0.006, QTd: r = 0.68, P < 0.025) and with plasma concentrations of both terodiline enantiomers. CONCLUSIONS: Terodiline increases QTc and QTd in a concentration dependent manner. It is not clear whether this is a stereoselective effect and, if so, which enantiomer is responsible. The results suggest that drug induced torsade de pointes is a type A (concentration dependent) adverse drug reaction.

Aged↗
PubMed1995

Appetite suppressants and primary pulmonary hypertension in the United Kingdom.

OBJECTIVE: Amphetamine-like appetite suppressants, particularly fenfluramines, have been implicated in the aetiology of primary pulmonary hypertension. At one specialist centre in France 20% of patients with primary pulmonary hypertension had been exposed to fenfluramine. The prevalence of primary pulmonary hypertension associated with fenfluramines and other appetite suppressants in the United Kingdom is unknown. This study was performed to measure prior exposure to appetite suppressants in patients with primary pulmonary hypertension. SETTING: Heart lung transplantation centres in England. PATIENTS: United Kingdom residents with proven primary pulmonary hypertension referred for consideration of heart lung transplantation. METHODS: Case surveillance study, obtaining data from the hospital and general practitioner's notes and directly from the patients or their relatives. RESULTS: 55 patients were identified. Drug histories were available from hospital records in all patients, from the general practitioner's notes in 51, and from the patients or relatives in 44. Of these, 3 female patients had been exposed to appetite suppressants (2 fenfluramine, 1 diethylpropion): 2 have since died. In each case exposure was brief and apparently predated the development of symptoms by several years. CONCLUSIONS: Exposure of patients with severe primary pulmonary hypertension to fenfluramine and other appetite suppressants is uncommon in the United Kingdom unlike in France, where most of the cases associating primary pulmonary hypertension with fenfluramine use have originated. This may reflect more conservative prescribing of these agents in the United Kingdom.

Adult↗
PubMed1995

Effect of a spacer on pulmonary aerosol deposition from a jet nebuliser during mechanical ventilation.

BACKGROUND: Several factors have been identified which improve nebulised aerosol delivery in vitro. One of these is the addition of a spacer to the ventilator circuit which improves aerosol delivery from a jet nebuliser to a model lung by approximately 30%. The current study was designed to demonstrate whether similar improvements could be demonstrated in vivo. METHODS: Ten patients (seven men) were studied during mechanical ventilation (Siemens Servo 900C) after open heart surgery. Aerosol was delivered using a Siemens Servo 945 nebuliser system (high setting) driving a System 22 Acorn jet nebuliser (Medic-Aid) containing 3 ml technetium-99m labelled human serum albumin (99mTc-HSA (50 micrograms); activity in the first nebulisation, 90 MBq; in the second nebulisation, 185 MBq). Central and peripheral lung aerosol deposition and the time to complete deposition were measured using a gamma camera and compared when the nebuliser was connected to the inspiratory limb using a simple T-piece or a 600 ml spacer. RESULTS: The addition of the spacer increased total lung deposition (mean (SD) percentage initial nebuliser activity) from 2.2 (0.7)% to 3 (0.8)%. There was no difference in the time required to complete nebulisation (18.2 min v 18.3 min respectively for T-piece and spacer) or in the retention of activity in the nebuliser (46.2% v 47.1% respectively). CONCLUSIONS: The combination of a spacer with a jet nebuliser increased lung deposition by 36% in mechanically ventilated patients and is a simple way of increasing drug deposition or reducing the amount of an expensive drug required for nebulisation.

Aerosols↗
PubMed1995

Lack of effect of inhaled morphine on exercise-induced breathlessness in chronic obstructive pulmonary disease.

BACKGROUND: Inhaled nebulised morphine may reduce breathlessness in patients with lung disease, although the results of controlled trials are conflicting. A direct action of morphine on the lung has been postulated. This study aimed to investigate whether nebulised morphine reduced exercise-induced breathlessness in patients with chronic obstructive pulmonary disease (COPD) and to determine if this was a local pulmonary effect or occurred after systemic morphine absorption. METHODS: A double blind, randomised, crossover study was performed in 12 men with COPD to compare the effects of nebulised morphine (10 and 25 mg), equivalent intravenous doses (1 and 2.5 mg), and placebo. Breathlessness (visual analogue scale), ventilation, gas exchange, and exercise endurance were measured during graded bicycle exercise. RESULTS: None of the treatments altered breathlessness, ventilation, or gas exchange at rest or at any time during exercise, and exercise endurance was unaffected. At peak exercise mean (95% CI) changes from placebo in ventilation were -0.8 (-0.57 to 1.1) l/min and -0.4 (-2.8 to 2.0) l/min for the highest intravenous and nebulised doses, respectively. For breathlessness equivalent values were +2 (-5 to 9) and +1 (-9 to 11) mm. The study was of sufficient power that it is unlikely that a clinically important effect was missed. CONCLUSIONS: Nebulised morphine in these doses has no effect on exercise-induced breathlessness. These findings do not support the hypothesis that intrapulmonary opiates modulate the sensation of breathlessness in patients with COPD.

Administration, Inhalation↗
PubMed1994

Effect of saliva flow rate on saliva phenytoin concentrations: implications for therapeutic monitoring.

The effect of atropine-induced reductions in saliva flow rate on saliva phenytoin concentrations were evaluated in a randomised placebo-controlled crossover study in a group of epileptic patients stabilised on the drug. Pretreatment with atropine caused significant reductions in saliva flow rates during the first 4 h, compared to saline. The AUC0-4 h for saliva flow rate was significantly reduced by atropine (245 g vs 327 g) and the saliva phenytoin AUC0-4 h was significantly increased (5.6 micrograms.ml-1.h vs 4.5 micrograms.ml-1.h) without affecting plasma phenytoin concentrations. The saliva/plasma phenytoin AUC0-4 h ratio was therefore significantly increased by atropine (0.15 vs 0.12). However, there was a poor correlation between saliva/plasma phenytoin concentration ratios and saliva flow rates for the two treatments in the individual patients (correlation coefficient ranged from 0.25 to 0.65). These findings demonstrate that saliva phenytoin concentrations are increased by reductions in saliva flow rate. Caution is therefore required when saliva phenytoin concentrations are used for therapeutic monitoring in the presence of factors which may affect saliva flow rate.

Adult↗
PubMed1994

Bilateral epidural empyemas in an adolescent.

Epidural empyema is an unusual cause of headache that may be encountered in the emergency department. The collection of suppurative fluid usually results from local spread of sinusitis, although many other predisposing factors have also been described. Patients with epidural empyema usually present with nonspecific cephalalgia that may be accompanied by fever and leukocytosis but is unlikely to be associated with focal neurological findings. The case of an adolescent who presented to our emergency department twice in 6 days with persistent headache is reported; cranial computed tomography performed on the second visit demonstrated bilateral epidural empyema. This entity is uncommon, but may certainly be encountered by the emergency physician.

Adolescent↗
PubMed1994

The ability to perform closed chest compressions in helicopters.

Critically ill patients are often transported by air ambulances. Although these patients are likely to require cardiopulmonary resuscitation (CPR) during transport, the effects of the air medical transport environment on CPR efficacy have never been studied. A manikin model was used to assess the ability of flight nurses to perform effective chest compressions while in flight and when stationery on the helipad. The results demonstrate that flight nurses were able to perform chest compressions as effectively in the in-flight setting as in the stationary setting. Chest c compressions performed in the BK-117 helicopter were as effective as those performed in the control environment, but compressions performed in the BO-105 were significantly less effective than controls. In conclusion, in a manikin model, chest compressions are substandard in the BO-105 helicopter because of the limited space available in the aircraft.

Air Ambulances↗
PubMed1994

Acute toxicity from baking soda ingestion.

Sodium bicarbonate is an extremely well-known agent that historically has been used for a variety of medical conditions. Despite the widespread use of oral bicarbonate, little documented toxicity has occurred, and the emergency medicine literature contains no reports of toxicity caused by the ingestion of baking soda. Risks of acute and chronic oral bicarbonate ingestion include metabolic alkalosis, hypernatremia, hypertension, gastric rupture, hyporeninemia, hypokalemia, hypochloremia, intravascular volume depletion, and urinary alkalinization. Abrupt cessation of chronic excessive bicarbonate ingestion may result in hyperkalemia, hypoaldosteronism, volume contraction, and disruption of calcium and phosphorus metabolism. The case of a patient with three hospital admissions in 4 months, all the result of excessive oral intake of bicarbonate for symptomatic relief of dyspepsia is reported. Evaluation and treatment of patients with acute bicarbonate ingestion is discussed.

Acute Disease↗
PubMed1994

Intravenous versus rectal prochlorperazine in the treatment of benign vascular or tension headache: a randomized, prospective, double-blind trial.

STUDY OBJECTIVE: To compare the effectiveness of i.v. and PR prochlorperazine for treatment of acute benign vascular or tension headache. DESIGN: Prospective, randomized, double-blind trial. SETTING: University emergency department with 50,000 annual census. PARTICIPANTS: Forty-five adult patients enrolled on 46 visits. INTERVENTIONS: Patients received 10 mg prochlorperazine i.v. and placebo suppository or 25 mg prochlorperazine PR and placebo injection. Pain assessment was made using a 10-cm visual-analog scale; scores were analyzed using Wilcoxon/Kruskal-Wallis rank-sum tests (alpha of .01). RESULTS: Mean 60-minute pain scores for i.v. and PR groups were 0.6 and 3.5, respectively (P = .0002). Two patients (8.7%) in the i.v. group and six patients (26.1%) in the PR group required rescue analgesia (P = .12). CONCLUSION: i.v. prochlorperazine appears to provide more effective relief than PR prochlorperazine for benign vascular or tension headaches.

Acute Disease↗