Biomedical subjects
Publications and source records attributed to R R Lewis.
Malabsorption in elderly patients has varied presentations, and can be overlooked. A high index of clinical suspicion is required. This, the first of two articles, discusses the principal causes, clinical features and initial investigations of malabsorption in the elderly.
After the initial assessment of elderly patients suspected of having malabsorption, as discussed in the first of this pair of articles, more specific investigations may be necessary. These are described in this article, together with the main treatment options that are available.
A comparison was made between the accuracy of Ames and Boehringer reagent strips for detecting urinary tract infections in 100 elderly patients (50 acutely ill patients admitted to hospital and 50 attending the day hospital). The results for urinary nitrite, blood and protein for both strips were documented. Nitrite provided the highest sensitivities and specificities. In the acute hospital patients, the sensitivities were 83% for the Ames and Boehringer strips respectively, while for the day hospital patients the sensitivities were 90% for both strips. Specificities were 100% for both strips in each group of patients. There was thus little difference between the accuracy of the Ames and Boehringer reagent strips in detecting urinary tract infection.
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Indirect (cuff) and direct (intra-arterial) BPs were measured in 15 normotensive (mean age 79 years, range 72-88 years) and 21 hypertensive (mean age 76 years, range 65-89 years) elderly patients. Osler's test and arm arterial compliance, measured using Doppler-shifted ultrasound, were also assessed. In the normotensive, cuff systolic pressures were less than the direct by > 20 mmHg in 10 of the 15 (mean cuff systolic 139 +/- 13: direct 160 +/- 20 mmHg, P < 0.001); there was no statistical difference between the cuff and direct mean diastolic pressures (mean cuff diastolic 75 +/- 8; direct 70 +/- 10 mmHg). In the hypertensives, one had pseudohypertension (cuff systolic 186: direct 152 mmHg). However, cuff systolic pressures were less than the direct by > 20 mmHg in 11 (mean cuff systolic 205 +/- 26: direct 224 +/- 31 mmHg, P < 0.05); cuff diastolic pressures were greater than the direct by > 10 mmHg in 10 (mean cuff diastolic 102 +/- 14; direct 93 +/- 16 mmHg, P < 0.05). There was no significant difference between cuff and direct mean arterial pressures or the compliance in the normotensive and hypertensive groups. Osler's test was negative in the pseudohypertensive patient while in the four positive tests cuff systolic pressures were less than the direct measurements. In elderly patients there was no significant difference between the mean BP for cuff and direct measurements; systolic pseudohypotension and diastolic pseudohypertension are common and Osler's test is misleading.
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The ability of transcranial pulsed Doppler ultrasound (TCD) to provide a dynamic assessment of the functional capability of the Circle of Willis was assessed using conventional cerebral angiography for anatomic correlation. Eleven patients had normal four-vessel cerebral angiography prior to being investigated with ultrasound. Angiography and ultrasound both demonstrated a functional anterior communicating artery in nine of the eleven patients, giving complete agreement between the two techniques. Posterior communicating arteries were visualized angiographically in all eleven patients. Ultrasound identified bilateral functional vessels in nine, the other two patients having non-functional vessels. In these latter two patients, angiography demonstrated three of the four posterior communicating arteries to be hypoplastic and it was uncertain whether these vessels carried significant blood flow. The fourth posterior communicating artery was shown to have an absent proximal segment of the ipsilateral posterior cerebral artery, with a persistent fetal posterior communicating artery. This anatomical variation is a potential limitation of ultrasound for assessing functional posterior communicating arteries. These preliminary results indicate that a combination of the anatomical (angiographic) and dynamic (ultrasonic) data may prove to be complementary for assessing the Circle of Willis.
OBJECTIVE: To determine the incidence of loss of consciousness occurring in association with shocks delivered by automatic implantable cardioverter-defibrillators (AICD) in patients who had undergone implantation as treatment for ventricular tachycardia or ventricular fibrillation. DESIGN: Cohort study. SETTING: Two major tertiary medical care facilities. PATIENTS: A total of 180 patients who had undergone implantation of an AICD for treatment of ventricular tachycardia or ventricular fibrillation. INTERVENTION: Implantation of an AICD that delivered only high-energy shock. MEASUREMENTS: During a mean (+/- SD) follow-up period of 16 +/- 12 months, the incidence of loss of consciousness occurring in association with spontaneous AICD shocks was determined. Various clinical factors were analyzed to identify predictors of loss of consciousness that occurred during AICD shocks. MAIN RESULTS: Of the 180 patients who received an AICD, 106 patients (59%) experienced AICD shocks during follow-up. Sixteen of the 180 patients (9%) experienced loss of consciousness; 13 of these 16 patients had syncope and 3 died suddenly, in association with AICD shocks. The absence of syncope during one AICD shock did not always predict the absence of syncope during subsequent shocks. Syncope could not be predicted by age, sex, history of syncope, left ventricular function, type of underlying heart disease, electrophysiologic findings, rate of ventricular tachycardia, antiarrhythmic medications, and type of pulse generator implanted. CONCLUSIONS: Patients with sustained ventricular tachycardia or ventricular fibrillation who receive an AICD that delivers only high-energy shock therapy are at moderate risk for experiencing loss of consciousness during AICD shocks. No clinical variables were found to be predictors of syncope. Therefore, driving and other activities that require patients to be extra vigilant should not be assumed to be safe after implantation of an AICD that delivers only high-energy shock.
Seventy-four patients (16 women, 58 men, age 58 +/- 11 years, mean +/- standard deviation) who received an implantable cardioverter defibrillator (ICD) after experiencing a single episode of ventricular tachycardia or ventricular fibrillation were followed to determine if antiarrhythmic drug therapy affects the incidence of ICD discharges. Thirty-three patients (group A) were treated with an antiarrhythmic drug that was either untested or previously demonstrated during electropharmacological testing to be ineffective in suppressing the induction of ventricular tachycardia. Forty-one patients (group B) were not treated with an antiarrhythmic drug. There were no significant differences between the two groups in regards to age, sex, incidence of coronary artery disease, left ventricular function or the type of ICD pulse generator used. During a mean follow-up of 14 months for the entire cohort, 15 patients (46%) in group A and 18 patients (44%) in group B experienced at least one ICD shock. The time to the first appropriate shock (5 +/- 5 months in both groups) and the frequency of ICD shocks (0.3 +/- 0.2/month in group A vs 0.4 +/- 0.5/month in group B) were similar in both groups. The incidence of syncope at the time of ICD discharge was higher in group A than group B patients (31% vs 5%, P less than 0.05). In conclusion, antiarrhythmic drugs that are untested or have failed electropharmacological testing do not appear to reduce the probability of ICD discharge over a short-term (mean 14 months) follow-up in patients who have had only one clinical episode of VT/VF and may increase the risk of syncope during ICD discharge.(ABSTRACT TRUNCATED AT 250 WORDS)
Fifty elderly patients who had suffered cerebrovascular incidents from no obvious cause and 33 age-matched controls were investigated for the presence of a patent foramen ovale by contrast 2-dimensional echocardiography at rest and after the Valsalva manoeuvre. Right-to-left shunting was found in only one patient and in none of the controls. This finding is in contradistinction to young adult stroke patients in whom the prevalence of a haemodynamically significant patent foramina ovale is high. Paradoxical embolism is an uncommon cause of stroke in the elderly.
The accuracy of reagent strip testing for urinary tract infection (UTI) was assessed in 100 elderly patients (50 acute patients admitted to hospital and 50 attending the day hospital). Reagent strip sensitivities were: acute patients-urinary nitrite 83%, blood 67%, protein 72% and leucocytes 72%, and day hospital patients-urinary nitrite 90%, blood 65%, protein 30% and leucocytes 60%. Urinary nitrite specificities were 100% for both groups of patients. Only 28% of patients with a UTI had specific symptoms of the infection; pyrexia and a raised WBC also proved poor indicators. Urinary nitrite was thus the most accurate immediate indicator of UTI.
Doppler-shifted ultrasound was used to measure arterial compliance non-invasively in the internal and external carotid pathways of 270 male and 388 female asymptomatic volunteers aged 5 to 90 years. There was a significant decrease in the compliance of both arteries from 5 to 50 years of age (p less than 0.001), when it then levelled out. Arteries of women were more compliant than those of men at ages 35 to 60 years.
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Doppler-shifted ultrasound was used as a non-invasive test to determine the presence of severe (pressure dropping) internal carotid lesions in two groups of elderly patients. Group 1 consisted of 150 hypertensive patients; these were subdivided into 77 who had had no cerebrovascular incidents (mean age 75 years, range 65-97) and 73 who had previously suffered a stroke (mean age 75 years, range 65-91). Group 2 consisted of 44 normotensive asymptomatic elderly volunteers (mean age 76 years, range 68-90). In the hypertensive patients (group 1), severe disease was detected in the non-stroke patients in 15 (10%) of the internal carotid arteries (14% of the patients), and in the stroke patients in 23 (16%) of the internal carotid arteries (23% of the patients). None of the normotensive volunteers (group 2) had evidence of severe internal carotid disease. Statistical analysis confirmed a highly significant difference in the prevalence of severe carotid disease between the normotensive and hypertensive subjects. The difference between the non-stroke and stroke hypertensive patients was not statistically significant.
Sixteen patients (mean age 59 +/- 9 years) who were to undergo carotid endarterectomy were examined pre- and peroperatively using pulsed Doppler-shifted ultrasound; blood velocities in the middle cerebral artery were measured before and during common carotid compression in the conscious patient, and before and during measurement of carotid stump pressures at surgery in the anaesthetized patient. Measurements at endarterectomy showed a significant difference in middle cerebral artery blood velocities from patients with stump pressures of greater and less than 50 mmHg (t = 4.0, P less than 0.005). A threshold of 10 cm s-1 distinguished between stump pressures of greater and less than 50 mmHg in 15 of the 16 patients. Pre-operative blood velocity measurements during carotid compression did not correlate with those taken peroperatively at carotid clamping.
We have determined the pharmacokinetics of meptazinol after its intravenous and intramuscular administration in a crossover study in 7 elderly hospital in-patients (greater than 70 years), and have compared with the results from 14 healthy, young volunteers (ages 20-40 years). The systemic availability after i.m. administration was comparable to that after i.v. administration, a result consistent with the physicochemical properties of the drug. There was a slight, but statistically significant (p less than 0.01) prolongation in t1/2Z in the elderly (mean 2.93 h) compared with the young (mean 2.06 h). This was associated with a 25% lower clearance in the elderly rather than with any alteration in volume of distribution. However, these changes would not appear to be substantial enough to require a revised dosage recommendation for meptazinol for this age group.
The results of a study to investigate possible underdiagnosis of hyperthyroidism in the elderly are reported. Four out of 24 patients with atrial fibrillation for which there was no obvious cause and who had normal thyroid hormone measurements were found to have subnormal thyrotropin responses to thyrotropin-releasing hormone and abnormal thyroid scans. The implications of this finding are discussed.