Alzheimer's disease: in vivo detection of differential vulnerability of brain regions

The severe cognitive impairment during the later stages of Alzheimer's disease is usually preceded by a selective disturbance in the ability to remember new experiences. With quantitative, high-resolution magnetic resonance imaging techniques, it is now possible to determine, in vivo, differences in the pattern of anatomical changes that might reflect behavioral symptomatology during different stages of the disease. In the present investigation, magnetic resonance imaging examinations were carried out in aged controls and in clinically diagnosed Alzheimer's disease patients who were divided into three groups based upon dementia severity. Atrophy of the hippocampal formation, a region important for memory function, was observed even in Alzheimer's disease patients with the mildest dementia. With more prominent dementia, atrophy extended to the parahippocampal gyrus and the temporal neocortex.

Criterion-related validity of the Geriatric Depression Scale in Alzheimer's disease

The effect of cognitive impairment on the criterion-related validity of the self-report Geriatric Depression Scale (GDS) was investigated in community-dwelling older adults. The GDS was administered to subjects with Alzheimer's disease (AD; n = 715) and normal cognitive function (NC; n = 93). The criteria consisted of the diagnosis of major depressive disorder and the total score on Hamilton Rating Scale for Depression, each derived from structured interview with a collateral informant to circumvent the effect of cognitive impairment on criterion measurement. Agreement between the GDS and both criteria was substantially attenuated in AD relative to NC subjects, differences primarily reflecting a lower than expected rate of item endorsement on the GDS in AD. A decrement in GDS validity coefficients was measurable across a broad range of cognitive impairment, suggesting limited utility of the scale in AD.

The effects of endobronchial cuff inflation on double-lumen endobronchial tube movement after lateral decubitus positioning

OBJECT

This study was designed to measure changes in tracheal and bronchial lumen distances from mainstem and secondary carina with lateral positioning, and to assess whether inflation of the endobronchial cuff before lateral positioning would further secure a double-lumen endobronchial tube (DLT) and reduce movement.

DESIGN

Prospective study.

SETTING

University-affiliated cancer center.

PARTICIPANTS

Fifty adult patients scheduled for elective thoracic surgical procedures requiring the placement of a left DLT.

INTERVENTIONS

Patients were sequentially assigned to either the endobronchial cuff-inflated group or the deflated group during lateral positioning. After induction of general anesthesia, a left polyvinylchloride (PVC) DLT was placed and the position confirmed. In the supine position, the distance from the tip of the tracheal lumen to main carina was measured using a fiberoptic bronchoscope (FOB) passed through the tracheal lumen, and the distance from the bronchial lumen to secondary carina was measured with the FOB passed through the bronchial lumen. The patients were then positioned laterally and a second set of measurements taken. Overall movement was determined by increases and decreases in tracheal and bronchial distances obtained by substracting supine values from lateral values.

MEASUREMENTS AND MAIN RESULTS

There was significant tracheal movement in 40 of 50 patients, with a mean of 0.92 +/- 1.0 cm. This was predominantly in the upward direction, as seen in 35 of 50 patients. There was significant bronchial movement in 37 of 50 patients, with a mean of 0.92 +/- 1.15 cm. Also, predominance in the upward direction was seen in 34 of 50 patients.

CONCLUSIONS

DLTs move with lateral positioning, regardless of endobronchial cuff inflation. The movement is predominantly in the upward direction. Therefore, fiberoptic visualization in the supine position should be used only to confirm that the endobronchial lumen is placed on the appropriate side and the cuff is at least 1 cm inside the left mainstem bronchus. Final positioning should always be verified in the lateral position.

Running a domiciliary nebuliser service

A nebuliser service should be provided locally, according to local needs. It should be centralised and administered by a designated consultant or consultants and written guidelines should be provided for medical and para-medical staff. The service should: (1) provide compressor/nebuliser units suitable for the prescribed treatment, (2) provide a system for equipment replacement, repair and maintenance, and (3) show patients how to use the equipment and give them comprehensive written instructions.

Nonoperative management of tracheal laceration during endotracheal intubation

Tracheal laceration is a rare but potentially devastating complication of endotracheal intubation. Traditional management of intubation-related tracheal laceration is operative. Nonoperative management of a woman noted to have a tracheal laceration during intubation is described. Criteria by which nonoperative treatment can be considered are outlined.

Does the lens diameter increase or decrease during accommodation? Human accommodation studies: a new technique using infrared retro-illumination video photography and pixel unit measurements

PURPOSE

To describe a new technique for viewing and measuring the lens diameter during accommodation.

METHODS

The accommodative lens activity, in a young female carrier of ocular albinism, was evaluated using retro-illumination infrared video photography and pixel unit measurements.

RESULTS

Right and left lens diameter measurements were 498 pu and 501 pu, respectively, during natural accommodation. In pharmacologic non-accommodation (Tropicamide), the average lens diameter was 524 pu (range 518-528) while in accommodation (Pilocarpine), the average lens diameter was 485 pu (range 479-491).

CONCLUSIONS

Right and left lens measurements were essentially identical. All measurements were reliable, repeatable and extremely accurate. The lens diameter consistently reduced during accommodation and enlarged during non-accommodation. The theories, similar to Tscherning's, which imply that the lens diameter increases in accommodation, are clearly disproven.

Severe lipoid pneumonia following attempted suicide by mineral oil immersion

Following an attempted suicide by drowning in a vat of mineral oil, a previously fit man survived the usually fatal lipoid pneumonia resulting from total immersion after intensive support and prolonged steroid therapy with recovery of chest radiography and pulmonary function at one year.

Value of perioperative Doppler echocardiography in patients undergoing major lung resection

BACKGROUND

The effects of major lung resection on right heart function have not been well established. Our goal was to evaluate these effects using serial Doppler echocardiography in the perioperative period.

METHODS

In 86 patients undergoing lobectomy (n = 47) and pneumonectomy (n = 39), we examined the effects of pulmonary resection on perioperative changes in right heart function by transthoracic echocardiography. Serial echocardiograms were performed preoperatively, on postoperative day 1, and again between postoperative days 2 and 6 (median, 3 days) to evaluate cardiovascular function and to estimate right ventricular systolic pressure by the tricuspid regurgitation jet Doppler velocity method.

RESULTS

Right or left atrial size, right atrial pressure, and estimated right ventricular systolic pressure did not differ between groups on the preoperative or postoperative day 1 examinations. However, on postoperative days 2 through 6 patients who underwent pneumonectomy had higher (mean +/- standard deviation) right ventricular systolic pressure values than lobectomy patients (31 +/- 15 versus 25 +/- 10 mm Hg, respectively; p < 0.05 by analysis of variance). In the subset of patients with percent predicted forced expiratory volume in 1 second less than 60% undergoing pneumonectomy (9/39), preoperative right ventricular systolic pressure was inversely correlated with percent predicted forced expiratory volume in 1 second values (r = -0.78; p < 0.04). This correlation was not significant in corresponding lobectomy patients. Postoperative right ventricular enlargement determined by echocardiography occurred with similar frequency in both groups and was associated with poor short-term prognosis in patients in whom severe respiratory failure developed.

CONCLUSIONS

Preoperative indices of right heart function were within the normal range in both groups. Pneumonectomy but not lobectomy was associated with mild postoperative pulmonary hypertension that was not accompanied by significant right ventricular systolic dysfunction. Postoperative echocardiography may be useful to evaluate right heart function in critically ill patients after lung resection.

Elastin fibers and the diagnosis of bacterial pneumonia in the adult respiratory distress syndrome

OBJECTIVE

It has been inferred from previous work that 40% potassium hydroxide preparations of lower respiratory tract secretions that demonstrate elastin fibers have a 100% specificity and positive predictive value in diagnosing bacterial pneumonia in intubated, mechanically ventilated patients without the adult respiratory distress syndrome (ARDS). Our aim was to assess the specificity of 40% potassium hydroxide preparations in diagnosing bacterial pneumonia in patients with ARDS and suspected pneumonia.

DESIGN

Prospective, case-referral clinical study.

SETTING

Referral hospital.

PATIENTS

Of 24 patients with ARDS who were intubated and mechanically ventilated with suspected bacterial pneumonia, 22 were assessable and evaluated for this report.

INTERVENTIONS

Tracheo-bronchial aspirates were obtained from all patients and analyzed for elastin fibers using 40% potassium hydroxide.

MEASUREMENTS AND MAIN RESULTS

Of the 22 assessable patients, ten patients did not have a complicating bacterial pneumonia. Six of these ten patients had potassium hydroxide preparations that demonstrated elastin fibers (false positives). The other four patients had preparations that did not demonstrate elastin fibers (true negatives). Specificity was 40%.

CONCLUSION

Elastin fiber preparations are not specific for diagnosing bacterial pneumonia in patients with ARDS.

Clinical and echocardiographic correlates of symptomatic tachydysrhythmias after noncardiac thoracic surgery

BACKGROUND

Supraventricular tachydysrhythmias (SVTs) following thoracic surgery occur with significant frequency and may be associated with increased morbidity. Prospective data on the etiology and importance of these dysrhythmias are sparse.

METHODS

In 100 patients undergoing pulmonary resection without history of atrial dysrhythmias or previous thoracic surgery, we examined the effects of predefined risk factors by history, pulmonary function, and echocardiography on the incidence of postoperative SVT. Serial echocardiograms were performed preoperatively, on postoperative day 1, and again between postoperative days 2 to 6 (median = 3) to evaluate cardiovascular function and to estimate right ventricular systolic pressure (RVSP) by the tricuspid regurgitation jet (TRJ) Doppler velocity method.

RESULTS

Symptomatic postoperative SVT occurred in 18 (18%) of the 100 patients studied at a median of 3 days after surgery and was disabling in 12 of 18 (67%). Digoxin loading was ineffective in controlling the ventricular response in 16 of 17 episodes. In the patients developing SVT, postoperative echocardiography revealed significant elevation of TRJ Doppler velocity (2.7 +/- 0.6 m/s vs 2.3 +/- 0.6 m/s, p < 0.05) but not right atrial or ventricular enlargement or right atrial pressure increase when compared with patients without SVT. Independent correlates of SVT determined in a stepwise logistic regression included intraoperative blood loss > or = 1 L (p = 0.0001) and a postoperative TRJ Doppler velocity > or = 2.7 m/s (p < 0.05). Patients who developed SVT had a higher rate of intensive care unit admission (p < 0.004), a longer hospital stay (p < 0.02), and higher 30-day mortality (p < 0.02).

CONCLUSIONS

These prospective data suggest that increased right heart pressure but not fluid overload or right heart enlargement predisposes to clinically significant SVT after pulmonary resection. SVT may be an important marker of poor cardiopulmonary reserve in patients who develop significant morbidity after thoracic surgery. Early interventions to reduce right heart pressure may decrease the incidence of postoperative SVT and potentially improve overall surgical outcomes.

Epidemiology of injury in people with Alzheimer's disease

BACKGROUND

Previous studies have suggested that the risk of injury is elevated among persons with dementia, but these studies have focused primarily on falls and fractures. This study characterizes all injuries incurred in a large sample of community-dwelling persons with a specific form of dementia, Alzheimer's disease (AD).

SUBJECTS AND METHODS

The sample consisted of 281 community-dwelling persons diagnosed with AD according to NINCDS/ADRDA guidelines. Information regarding all injuries occurring within the previous 6 months was obtained through a structured interview of a caregiver.

RESULTS

The rate of injuries was 58.4 per 100 persons per year. Although falling was the single most common mechanism by which injuries occurred, it accounted for only 43.8% of all injuries. Fractures accounted for 13.7% of injuries. Medical treatment was sought for 52.1% of the injuries. After adjustment for age and gender, the likelihood of injury was significantly associated with cognitive impairment and with ADL limitation, but the independent contribution of these two factors could not be assessed.

CONCLUSIONS

The findings suggest that injuries are a significant problem in persons with AD.

Cardiorespiratory effects of volume- and pressure-controlled ventilation at various I/E ratios in an acute lung injury model

Numerous approaches to the provision of mechanical ventilation during acute lung injury are currently available. Of these, pressure control inverse ratio ventilation has been considered superior to volume control ventilation with PEEP with respect to improving gas exchange and minimizing cardiovascular compromise. However, no study systematically compares volume-controlled (VC) and pressure-controlled (PC) ventilation while maintaining mean airway pressure (MAP) constant at varying I/E ratios. We studied the effect of VC and PC with PEEP at normal (1:2) and inverse I/E ratios (2:1 and 4:1) on gas exchange, lung mechanics, and hemodynamics in a sheep lung injury model. Severe lung injury was induced in 12 sheep with bilateral lung lavages using normal saline; prelavage PO2 230 +/- 50 mm Hg, PEEP 5 cm H2O and postlavage, pretreatment PO2 70 +/- 20 mm Hg, PEEP 10 cm H2O, both at FIO2 0.50. MAP was kept constant throughout the study at 25 +/- 2 cm H2O while ventilating all animals with a VT of 10 ml/kg and a rate of 20/min by randomized application of VC and PC with I/E ratios of 1:2, 2:1, and 4:1. Despite liberal fluid administration, all ventilatory modes depressed cardiac output compared with preinjury values. However, gas exchange and hemodynamics did not differ among ventilation modes or I/E ratios.(ABSTRACT TRUNCATED AT 250 WORDS)

Intact text-specific implicit memory in patients with Alzheimer's disease

The ability of patients with Alzheimer's disease (AD) to acquire and retain text-specific knowledge was investigated in a re-reading study. Patients and normal control Ss read 2 passages 3 times, each as quickly as possible, and answered recognition memory questions after the 3rd reading of each passage. The AD patients had poor explicit memory as evidenced by impaired recognition memory for the passages. In contrast, normal decreases in the times required for successive readings of each passage for AD patients indicated intact implicit memory for the passages. The absence of facilitation across passages indicated that the re-reading effect was text specific, suggesting that AD patients may retain the ability to form certain kinds of implicit new associations. Alternative accounts of the mechanism underlying text-specific priming, and of the nature of intact and impaired implicit memory in AD, are considered.

Superiority of aztreonam/clindamycin compared with gentamicin/clindamycin in patients with penetrating abdominal trauma

There were 73 evaluable patients entered into a prospective, double-blinded trial comparing aztreonam/clindamycin (A/C) to gentamicin/clindamycin (G/C) for the prevention of infection after penetrating abdominal trauma. Aztreonam was administered at a dosage of 2 g every 8 hours and gentamicin at 5 mg/kg for the first 24 hours and then adjusted by serum monitoring to a peak of 6 to 8 micrograms/mL and a trough of less than 2 micrograms/mL; all patients received 900 mg of clindamycin every 8 hours. Patients with colon wounds received 4 days of antibiotics, and the remaining patients received a 24-hour course. Gunshot wounds occurred in 69% of patients: 74% of all patients had some hollow viscus injury, and 26% had only solid viscus injury. The groups were well matched according to abdominal trauma index, percentage with colon injury, and transfusion requirements. Failures occurred in eight patients (11%): two wound infections, five intra-abdominal infections, and one case of necrotizing fasciitis. Seven infections occurred in 36 (19%) G/C patients compared with 1 in 37 (3%) A/C patients (p < 0.03). The hospital stay was 12 +/- 11 days for G/C patients and 8 +/- 7 for A/C patients (p < 0.12). The superiority of the A/C regimen may be partially attributable to relative underdosing of gentamicin (approximately half of the patients had inadequate levels after 24 hours) combined with a favorable pharmacokinetic profile (significantly prolonged half-life) of aztreonam in this clinical setting.

Intact text-specific implicit memory in patients with Alzheimer's disease

The ability of patients with Alzheimer's disease (AD) to acquire and retain text-specific knowledge was investigated in a re-reading study. Patients and normal control Ss read 2 passages 3 times, each as quickly as possible, and answered recognition memory questions after the 3rd reading of each passage. The AD patients had poor explicit memory as evidenced by impaired recognition memory for the passages. In contrast, normal decreases in the times required for successive readings of each passage for AD patients indicated intact implicit memory for the passages. The absence of facilitation across passages indicated that the re-reading effect was text specific, suggesting that AD patients may retain the ability to form certain kinds of implicit new associations. Alternative accounts of the mechanism underlying text-specific priming, and of the nature of intact and impaired implicit memory in AD, are considered.

Comparison of dementia criteria: sensitivity and specificity testing among African American patients

We compared the sensitivity and specificity of recently proposed general dementia, vascular dementia, and Alzheimer's disease criteria using the DSM III-R as the 'gold standard' among 61 elderly African American patients. There were 10 patients with vascular dementia, 20 with Alzheimer's disease and 31 controls. Comparison of the sensitivity and specificity of the various criteria showed that with few exceptions, the results were similar. Additional studies of this kind among different populations, and among mild dementia patients, are needed to cross-validate the results.

Pathological changes in frontal cortex from biopsy to autopsy in Alzheimer's disease

We evaluated the change in density of total senile plaques, plaque subtypes, and neurofibrillary tangles, from biopsy to autopsy in left frontal cortical sections from four patients with clinically typical Alzheimer's disease (AD). Comparisons were made on sections stained with modified Bielschowsky and Thioflavin S. In two cases, comparisons were also made on tissue stained with a monoclonal Alz-50 antibody and an antiserum to A beta (beta-amyloid protein). Despite a marked decline in mental status over several years of follow-up clinical evaluations, there was no consistent significant change in numerical density of plaques or tangles among the four cases. However, we did find fewer primitive plaques in the autopsy specimens. These results from longitudinally evaluated persons with typical AD suggest that although plaques and tangles may serve as adequate markers of the presence of AD, their numerical density within a single neocortical region may not reflect dementia severity. This conclusion supports the results of recent cross-sectional studies on the progression of pathology among persons with AD.

Methadone combined with clonidine versus clonidine alone in opiate detoxification

The availability and use of a methadone/clonidine combination versus clonidine alone in opiate detoxification were studied. In Phase I of the study, a sequential combination of methadone followed by clonidine was utilized in those patients presenting with a primary diagnosis of opiate dependence. During the Phase II of the study, only clonidine was available. Medications were administered only if the history and clinical findings indicated impending or acute opiate withdrawal syndrome. Overall, there was no difference between the Phase I and Phase II groups when the number of opiate dependent admissions, patients completing detoxification, and the patients completing a follow-up rehabilitation program were compared. However, the patients in Phase I whose clinical symptomatology warranted the use of methadone were more likely to complete the detoxification program when compared to the patients in Phase II who received clonidine only. There was no difference between the two groups in completion of a follow-up rehabilitation. Detoxification with clonidine alone was more likely to be successful if the patient has had prior detoxification experience with methadone or if there was a secondary dependence of alcohol, sedative, or tranquilizer present coexisting with the primary opiate dependence diagnosis.