Demonstration of dilatation of peripheral airways

Summary. To investigate the ability of various lung-function tests to demonstrate dilatation of peripheral airways, ten asthmatics inhaled increasing doses of a f2-agonist by two different and controlled techniques. Low inspiratory flow with a long post-inspi-ratory pause favoured peripheral deposition, and a high inspiratory flow with a short post-inspiratory pause favoured central deposition of drug in the airways. Ordinary spirometry, maximum expiratory flow rates after breathing air as well as a helium-oxygen mixture, a single breath N₂-test and resistance of the respiratory system were obtained before and after each of five terbutaline doses with both inhalation techniques. By using a double-dummy technique, the study could be performed double blinded. Effects were compared at doses giving equal effects on PEF, assumed to represent equal deposition of bronchodilator and effects on central airways. At such ‘iso A PEF doses’, particularly FVC and the slope of phase III of the N₂-test improved more following the slow inhalation technique. It is concluded that changes in those tests reflect dilatation in peripheral airways in asthmatics.,     

Pronounced bronchial hyper-responsiveness and asthma severity

Summary. Fifty-six asthmatics from an asthma ward or from an asthma out-patient clinic were challenged with two low concentrations (0–03 and 0–012 mg) of metacholine chloride in order to assess the relationship between pronounced hyper-responsiveness and asthma severity in a clinical setting. Only inhaled bronchodilators were stopped before challenge. Asthma severity was assessed retrospectively and prospectively on the basis of treatment, number of days in hospital, intensive care, number of emergency visits and days on sick-leave. The results show that pronounced hyper-responsiveness (n= 28) is not associated with asthma severity. It is concluded that a single simplified test of pronounced bronchial hyper-responsiveness, performed without taking into consideration the actual state of the disease and without stopping all medication, is of no help in identifying the patients with the clinically most severe asthma and worst prognosis.,     

Validity of the "airflometer"--a simple device for assessment of forced expiration.

The device is basically a plastic turbine with a reduction gear (approximately 1:300) driving an indicator. Following a forced expiration on the indicator comes to rest after about 30 s, when it is read. The reading appears to be generated by the expired flow versus time pattern, and during a forced expiration, close to maximum speed for the turbine is reached within 0.5 s. In a given subject repeated measurements with the same apparatus varied within a few per cent, whereas the variation was considerable among different apparatuses. Readings correlated about equally well with FEV0.5 and FEV1.     

Ethanol exposure during pregnancy persistently attenuates cranially directed blood flow in the developing fetus: evidence from ultrasound imaging in a murine second trimester equivalent model

Background: Ethanol (EtOH) consumption during pregnancy can lead to fetal growth retardation, mental retardation, and neurodevelopmental delay. The fetal brain initiates neurogenesis and vasculogenesis during the second trimester, and depends on maternal‐fetal circulation for nutrition and growth signals. We used high‐resolution in vivo ultrasound imaging to test the hypothesis that EtOH interferes with fetal brain‐directed blood flow during this critical developmental period. Methods: Pregnant mice were lightly anesthetized on gestational day 12 with an isoflurane/oxygen mixture. We assessed the effect of single and repeated binge‐like maternal EtOH exposures at 3 g/kg, administered by intragastric gavage or intraperitoneal injection, on maternal circulation and fetal umbilical, aortic, internal carotid, and middle cerebral arterial circulation. Results: Binge maternal EtOH exposure, regardless of exposure route, significantly reduced fetal arterial blood acceleration and velocity time integral (VTI), from umbilical to cerebral arteries, without a change in fetal heart rate and resistivity indices. Importantly a single maternal binge EtOH exposure induced persistent suppression of fetal arterial VTI for at least 24 hours. Repeated binge episodes resulted in a continuing and persistent suppression of fetal VTI. Qualitative assessments showed that maternal EtOH exposure induced oscillatory, nondirectional blood flow in fetal cerebral arteries. Maternal cardiac and other physiological parameters remained unaltered. Conclusions: These data show that binge‐type maternal EtOH exposure results in rapid and persistent loss of blood flow from the umbilical artery to the fetal brain, potentially compromising nutrition and the maternal/fetal endocrine environment during a critical period for neuron formation and angiogenesis in the maturing brain.     

Spirometric reference equations for Swedish adults

New spirometric reference equations for Swedish adults are required. Three different older sets of reference equations clinically used in Sweden have various drawbacks and the recently published ‘The Global Lung Function 2012 (GLI) equations’ have been shown not to be adequate for Swedish normal, healthy non‐smokers. We have recently concluded that a piecewise linear model presented by Lubinski and Gólczewski accurately describes the distribution of spirometric variables in a large Swedish random population sample. This piecewise linear model also offers the important advantage of implementing easily physiologically interpretable coefficients. The present study aimed at presenting piecewise linear reference equations for Swedish adults based on a random population sample of 6685 individuals aged 25–75 years. Predicted normal values by the piecewise linear reference equations and lower limit normal (LLN) were compared with the three reference equations frequently used clinically in Sweden and the GLI equations. We found predicted normal values according to the present piecewise linear reference equations close to 100% predicted normal as expected, whereas the other equations either overestimated or underestimated normal subjects. Concerning LLN, the present equations, i.e. 1·645 × RSD, showed the least deviation from the expected 5% and, e.g., the GLI equations systematically identified too few subjects below LLN. We conclude that the present piecewise linear reference equations, based on a relatively large general population sample, ought to be considered for clinical use in Sweden. Application of 1·645 × RSD below predicted value gave an acceptably accurate LLN.     

Blood volume control by biofeedback and dialysis-induced symptomatology. A short-term clinical study

In earlier studies, a reduction in intradialytic procedures was observed in patients with severe intradialytic hypotension symptomatology by the use of blood volume controlled biofeedback systems. However, few data are present on the use of biofeedback-controlled treatments in patients experiencing minor intradialytic symptoms. In the present study, 157 standard and 158 biofeedback-controlled treatments were compared during a 2-month period in 16 hemodialysis patients. Both the percentage of hypotensive episodes (6.3 +/- 11.3 vs. 15.8 +/- 18.3%; p < 0.05) as well as other intradialytic symptoms (cramps, nausea, headache, abdominal pain) (11.0 +/- 12.8 vs. 18.1 +/- 16.9%; p < 0.05) were significantly less during biofeedback-controlled treatments compared to standard dialysis treatments, despite a similar decline in relative blood volume (8.8 +/- 3.5 vs. 8.3 +/- 3.1%; p = n.s.). Interdialytic weight gain and intradialytic rise in plasma sodium levels were comparable. Concluding, in this short-term preliminary study, blood volume controlled biofeedback improved dialysis tolerance also in patients with minor intradialytic symptomatology.     

Does undernutrition contribute to diaphragm weakness in patients with severe COPD?

BACKGROUND AND AIMS: The assumption that undernourishment contributes to diaphragm weakness in chronic obstructive pulmonary disease (COPD) remains unproven. METHODS: We, therefore, studied diaphragm strength, measured as transdiaphragmatic pressure during a maximal voluntary sniff (Sn P(di)) and cervical magnetic stimulation (Tw P(di)), in two groups of 10 patients with severe COPD. The groups had equally severe COPD as judged by FEV(1) and thoracic gas volume (V(tg)). The malnourished group had a mean body mass index (BMI) of 17.3 kg/m(2) compared with 27 kg/m(2) for the normally nourished group (mean difference -9.7 kg/m(2); 95% confidence intervals -6.8 to -12.6 kg/m(2),P <0.0001). RESULTS: There was no significant difference between Tw P(di) (mean difference 2.1 cm H(2)O; 95% CI-3 to + 7.4 cm H(2)O, P=0.39) or Sn P(di) (mean difference -2.4 cm H(2)O; 95% CI-21 cm H(2)O to +16 cm H(2)O,P =0.8). CONCLUSION: We conclude that undernourishment of the severity studied does not contribute to diaphragm weakness in severe COPD.     

Regional pulmonary ventilation and perfusion distribution in patients with untreated idiopathic scoliosis

Regional lung function using xenon-133 was studied in 45 seated patients aged 11 to 78 years with untreated idiopathic scoliosis and angulation of curvature between 10 and 190°. Perfusion distribution was assessed by intravenous bolus injection of ¹³³Xe and distribution of ventilation to volume ratios by washouts after inhalation and intravenous injection.