Clinical aspects of occupational pathology caused by noise and vibration

The paper is concerned with the results of many year-old clinical studies on workers of vibration-risk and "noisy" professions. The authors consider occupational and biomedical risk factors contributing to the development of vibratory disorders and noisy cochlear neuritis, the main clinical syndromes of this occupational pathology, modern methods of their preclinical and early clinical diagnosis. The basic principles of differentiated follow-up and combined prevention as well as problems of therapy, medical labor examination and rehabilitation of patients with vibratory disease and occupational cochlear neuritis are described.     

Trying versus liking fruits and vegetables: correspondence between mothers and preschoolers

Extensive research indicates that a diet rich in fruits and vegetables (F&V) protects against numerous illnesses in adulthood, but that most individuals, including children, consume far fewer F&V per day than is recommended. Since evidence suggests that eating habits in childhood track into adulthood, more research is necessary to learn about how parental F&V intake and opportunities influence child F&V consumption. The purpose of this study was to examine the relationship between mothers' F&V preferences and those of their preschool-age children to determine if greater maternal "liking" of fruits and vegetables was associated with their reports of their children's "trying" more fruits and vegetables. Eighty-three mothers completed a questionnaire that assessed whether they and their preschoolers had tried or liked a variety of F&V. Mothers liked 86% of the fruits they tried, girls 76%, and boys 69%. Mothers liked 81% of the vegetables they tried; boys and girls liked 55%. Mothers' likes correlated with F&V that their children tried, but mothers' likes also limited the number of F&V that their children tried. Mothers reported preferences for F&V are associated with estimates of their preschoolers' preferences for F&V. Relative to girls, boys may need additional opportunities for F&V exposure.     

Characterization of the cerebral blood flow response to balloon deflation after temporary internal carotid artery test occlusion

The authors tested the hypothesis that cerebral blood flow (CBF) would increase after acute and relatively brief internal carotid artery (ICA) test occlusion, and examined the relationship of the postdeflation CBF to the development of neurologic symptoms. In 16 patients undergoing ICA test occlusion with deliberate hypotension, the authors measured intracarotid 133Xe CBF at baseline, occlusion, and deflation. Four patients developed neurologic symptoms during occlusion. As positive controls, 11 other patients received intracarotid verapamil or papaverine before deflation as part of another protocol. Balloon occlusion was 23.1 +/- 10.5 minutes (mean +/- standard deviation) in duration. At 1.3 +/- 1.6 minutes after balloon deflation, there was a trend (12 +/- 31%) for CBF to increase (48 +/- 9 mL/100 g/min versus 53 +/- 17 mL/100 g/min, P =.15), and a 16 +/- 27% decrease in cerebrovascular resistance (CVR; 2.1 +/- 0.6 mm Hg/100 g/min/mL versus 1.7 +/- 0.6 mm Hg/100 g/min/mL, P =.03) compared with baseline values. By comparison, patients who received a intracarotid dilator demonstrated a 53 +/- 55% increase in CBF (48 +/- 10 mL/100/min versus 70 +/- 23 mL/100 g/min, P = .007) and a 33 +/- 31% decrease in CVR (2.2 +/- 0.6 mm Hg/100 g/min/mL versus 1.4 +/- 0.6 mm Hg/100 g/min/mL, P = .0007) compared with baseline. Analysis of variance and regression analysis showed no other relationships between postocclusion CBF and balloon occlusion duration, distal internal carotid occlusion ("stump") pressure, or the development of neurologic symptoms. Acute, temporary interruption of ICA blood flow resulted in minimal postocclusive changes in cerebrovascular hemodynamics, even in those patients who developed neurologic symptoms during the period of test occlusion.     

Acute Ischemic Injury on Diffusion-Weighted Magnetic Resonance Imaging after Poor Grade Subarachnoid Hemorrhage

Background

Poor clinical condition is the most important predictor of neurological outcome and mortality after subarachnoid hemorrhage (SAH). Rupture of an intracranial aneurysm was shown to be associated with acute ischemic brain injury in poor grade patients in autopsy studies and small magnetic resonance imaging series.

Methods

We performed diffusion-weighted magnetic resonance imaging (DWI) within 96 h of onset in 21 SAH patients with Hunt–Hess grade 4 or 5 enrolled in the Columbia University SAH Outcomes Project between July 2004 and February 2007. We analyzed demographic, radiological, clinical data, and 3 months outcome.

Results

Of the 21 patients 13 were Hunt–Hess grade 5, and eight were grade 4. Eighteen patients (86%) displayed bilateral and symmetric abnormalities on DWI, but not on computed tomography (CT). Involved regions included both anterior cerebral artery territories (16 patients), and less often the thalamus and basal ganglia (4 patients), middle (6 patients) or posterior cerebral artery territories (2 patients), or cerebellum (2 patients). At 1-year, 15 patients were dead (life support had been withdrawn in 6), 2 were moderately to severely disabled (modified Rankin Scale [mRS] = 4–5), and 4 had moderate-to-no disability (mRS = 1–3).

Conclusions

Admission DWI demonstrates multifocal areas of acute ischemic injury in poor grade SAH patients. These ischemic lesions may be related to transient intracranial circulatory arrest, acute vasoconstriction, microcirculatory disturbances, or decreased cerebral perfusion from neurogenic cardiac dysfunction. Ischemic brain injury in poor grade SAH may be a feasible target for acute resuscitation strategies.     

Intraoperative 133Xe cerebral blood flow measurements by intravenous versus intracarotid methods

To document the comparability of cerebral blood flow (CBF) values determined by quantification of 133Xe washout after either intravenous or intracarotid administration, 12 patients undergoing elective carotid endarterectomy anesthetized with N2O/O2 and either isoflurane or halothane were studied. Scintillation counters were placed over the middle cerebral artery territory ipsilateral to the operated carotid artery. CBF was measured by the intravenous method during dissection of the carotid sheath and was calculated as the initial slope index from head washout curves collected for 11 min after injection of 10-20 mCi 133Xe in saline into a large vein. Immediately prior to carotid occlusion, CBF was determined by direct injection of 1 mCi 133Xe in saline into either the internal carotid artery or the common carotid artery with the external carotid artery occluded. For the intracarotid injections, the initial slope was calculated from the 1st min of washout. Data were analyzed by linear regression and analysis of variance. Values are expressed as mean +/- SD. The mean CBF for intravenous and intracarotid methods were both 29 +/- 10 ml.100 g-1.min-1. The correlation between CBF measured by intravenous and intracarotid methods was excellent and was described by the line y = x + 0.6, r = 0.92. We conclude that in the flow range studied, the intravenous technique may be applied to measure CBF in physiologically stable situations in which direct intracarotid injection is not feasible.     

Adenosine-induced Ventricular Asystole to Induce Transient Profound Systemic Hypotension in Patients Undergoing Endovascular Therapy: Dose-Response Characteristics

Background: Adenosine-induced asystole has been used to induce transient systemic hypotension for various vascular procedures. Dose-response characteristics of adenosine-induced ventricular asystole have not been determined.

Methods: During endovascular embolization of cerebral arteriovenous malformations, the authors performed a series of adenosine test injections to establish a dose-response relation in each patient. After an interval of 3-10 min, the dose was escalated by 10-20 mg for each injection to achieve an end point of 20-30 s of stable mean arterial pressure (MAP) reduction to 25-30 mmHg. All patients received constant infusion of nitroprusside ([almost equal to] 1 [mu]g [middle dot] kg-1 [middle dot] min-1) throughout the procedure.

Results: The authors studied four adult patients (age, 22-44 yr; two patients had two separate procedures) and one pediatric patient (age, 4 yr). Twenty-three adenosine injections resulted in measurable asystole. The adenosine dose was 0.98 +/- 0.40 mg/kg (mean +/- SD), and the dose range was 0.24-1.76 mg/kg (6-90 mg). The duration of asystole, MAP < 30 mmHg, and MAP < 50 mmHg, were 8 +/- 3 s, 18 +/- 12 s, and 50 +/- 29 s, respectively. The minimum MAP and the MAP for the first 20 s were 16 +/- 3 mmHg and 30 +/- 9 mmHg, respectively. There was a linear relation between adenosine dose and the duration of hypotension with MAP < 30 mmHg and MAP < 50 mmHg.