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PubMed1987

[Scintigraphic study (81mKr) of venous return activation using intravenous dihydroergotamine].

We study by 81mKr radionuclide phlebography 13 normal lower limbs and 22 limbs suffering from sequelae of deep vein thrombosis. We assess the spontaneous venous return and the effect of an intravenous injection of 0.5 mg dihydroergotamine (DHE), a powerful venoconstrictor agent. The phlebograms are analysed on a morphological basis. Dynamic data are also collected: the delay of arrival of the radioactivity at the groin and the regional radioactivity level at steady state (during the steady 81mKr perfusion). This segmental radioactivity is a positive marker of the venous stasis because it increases when the venous system dilates and when the flow goes down. It is normalized with regard to the radioactivity measured in the proximal segment (lower vena cava and proximal iliac vein). The influence of DHE on the delay of arrival of the radioactivity in the groin is variable: it is regularly and significantly shortened in the normal limbs (mean decrease of 6.5 s, table II). The segmental radioactivity is relatively low among these limbs (2.76 at the pelvic level, 9.68 at the high, tables IV and V). It drops significantly with DHE in all segments (tables IV and V: -44% in the pelvic veins, -57% in the great saphenous vein and -46% in the femoral tract). The post-thrombotic limbs showing spontaneously an abnormal deep network are characterized by a high radioactivity level (total in the high: 14.25, deep system 5.70 and 8.55 in the saphenous vein, table V). This segmental total radioactivity does not decrease significantly under the influence of DHE; even more it increases in the deep tract (+24%, table V).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Inhaled smoke volume and puff indices with cigarettes of different tar and nicotine levels.

Ten asymptomatic smokers each smoked a low, low-to-middle and a middle tar cigarette with approximately the same tar-to-nicotine ratio, in a randomised order. The inhaled smoke volume was measured by tracing the smoke with the inert gas 81Krm. Puffing indices were recorded using an electronic smoking analyser and flowhead/cigarette holder. Throughout the study neither the mean inhaled smoke volume per puff nor the total inhaled smoke volume per cigarette changed significantly; however, the mean and total puff volumes were largest with the low tar cigarette and decreased with the higher tar brands. Puff volume was related to puff work (rs = 0.83, P less than 0.001) but was not related to puff resistance (rs = 0.10, P greater than 0.1). It is concluded that when switched between brands with the same tar-to-nicotine ratio, smokers increase their puff volumes with a lower tar cigarette but do not change the volume of smoke inhaled. Puff work and puff resistance were significantly correlated (rs = 0.45, P less than 0.02).

Adolescent↗
PubMed1986

Lung ventilation studies with technetium-99m Pseudogas.

Technetium-99m Pseudogas is an ultrafine near monodisperse aerosol of 0.12-microgram diam particle size. This report describes initial clinical experiences with 27 patients referred for investigation of suspected pulmonary embolism, and in whom Pseudogas ventilation images were compared with a high quality commercial aerosol. An additional group of ten patients with severe COPD was examined in a comparative trial of Pseudogas with 81mKr. Pseudogas was better than a conventional aerosol in reaching a diagnosis of pulmonary embolism using a simple blinded comparison with coded images. In addition, bronchial deposition was minimal unless COPD was severe. Moderately well patients had no difficulty inhaling the necessary activity in one or two breaths, and even severely ill and frail aged persons could accomplish the passive breathing maneuver in less than a minute. Clearance of Pseudogas was directly to the systemic circulation with a half-time of 10 min in normal subjects extending up to 100 min in patients with airways disease.

Adolescent↗
PubMedDate not supplied

[Isotope studies in the detection of pulmonary embolism].

The regional absence of perfusion in the territory situated downstream of a lung embolus can be visualized using a gamma camera and 99m Technetium labelled macroaggregated albumin of albumin microspheres. This is a simple and atraumatic procedure. Following intravenous injection these particles are blocked in the pulmonary capillaries, their distribution in the lungs being proportional to the regional perfusion. A normal perfusion scan virtually excludes pulmonary embolism. Pulmonary embolism typically causes a wedge shaped perfusion defect at one or more sites. However, a regional perfusion defect by itself can not be regarded as a specific sign of pulmonary embolism, since it may be found in many other lung diseases. In most pulmonary diseases matched perfusion and ventilation defects are found. In the case of pulmonary embolism ventilation is usually normal in the ischemic area. To differentiate pulmonary embolism from other lung diseases, a ventilation scan is therefore mandatory in addition to the perfusion scan. For this purpose radioactive inert gases such as 81mKrypton or 133Xenon may be used, or aerosols labelled with 99mTechnetium. Each of these methods has its own advantages and shortcomings. Criteria which may be helpful for the interpretation of combined ventilation/perfusion scans are presented.

Humans↗
PubMedDate not supplied

Mucus clearance from peripheral and central airways of asymptomatic cigarette smokers.

Insoluble radioaerosol particles have been used to monitor mucus clearance from peripheral, intermediate and inner lung zones. Nine asymptomatic cigarette smokers and nine healthy non-smokers who closely matched them for age, height and lung function were each tested twice under differing radioaerosol inhalation conditions ('high' and 'low' flow rate inhalation), so that clearance differences between smokers and non-smokers should not be masked by apparent clearance differences merely resulting from differing aerosol deposition patterns. Peripheral zone clearance in the smokers was closely similar to that in the non-smokers and was affected very little by changing from 'low' to 'high' flow rate inhalation. Inner zone clearance (calculated by a method which makes allowance for material cleared into the inner zone from more distal airways) was significantly slower in smokers than in nonsmokers for both inhalation conditions. In fact, inner zone clearance in the smokers after 'high' flow inhalation (favouring central aerosol deposition) was slower (p congruent to 0.05) than in the non-smokers after 'low' inhalation (favouring relatively peripheral deposition).

Adult↗
PubMed1978

Intrarenal blood flow distribution during endotoxemia in dogs.

Intrarenal blood flow distribution during the stages of endotoxemia in the dog was studied using radioactive inert gas washout. Intrarenal blood flow distribution was determined: a) at control, b) 0.5 hours following injection of a lethal dose (3 mg/kg) of E coli endotoxin, and c) 2.5 hours following endotoxin injection in control dogs and dogs pretreated with 4 mg/kg of phenoxybenzamine. One-half hour following endotoxin injection, components I and II of the inert gas washout curve fused. Presumably this fusion occurred because component I flow decreased to a level indistinguishable from that of component II. Following 2.5 hours of endotoxemia, components I and II were both present. Pretreatment with phenoxybenzamine completely prevented the fusion of components I and II, although the mean arterial blood pressure was substantially lower than in dogs not pretreated with phenoxybenzamine. After 2.5 hours of endotoxemia, four of the five phenoxybenzamine pretreated dogs still had two clearly defined washout components. It is concluded that the renal cortical vascular response in endotoxemia is similar to that reported following hemorrhage and that the alpha-adrenergic nervous system plays a major role in decreasing renal cortical blood flow.

Animals↗