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Biomedical subjects

B Jonson

Publications and source records attributed to B Jonson.

At least 127 records · Page 7Linked to original sources
PubMed1983

Automated rhinomanometry.

In order to facilitate measurements and calculations in rhinomanometry a microprocessor is used. Pressure and flow signals, obtained from microtransducers, are automatically calibrated by drawing known volumes of air through a standardized test-nose, while the signals are read by the computer. When the patient is connected, the pressure-flow curves are displayed on a screen. At adequate breathing, the computer reads the pressure and flow 200 times per second for a few breaths. It performs all calculations and presents data describing the pressure-flow relationship, e.g. in terms of the resistance, where the curve crosses a circle with a certain radius in a polar coordinate system. Automatically calculated data were compared to manually derived ones in six healthy subjects and twenty patients with symptoms of nasal obstruction. There was a close correlation between the two sets of data. It is concluded that the described automated rhinomanometer facilitates the rhinomanometric procedure and gives accurate data on nasal airway resistance.

Airway Resistance↗
PubMed1981

The concept of deadspace with special reference to the single breath test for carbon dioxide.

We present a review and a theoretical analysis of factors determining airway deadspace (VDaw) and alveolar deadspace (VDalv), the two constituents of physiological deadspace (VDphys). VDaw if the volume of gas between the lips and the alveolar/fresh gas interface, the location of which is determined by inspiratory flow pattern and airway geometry. VDalv can be caused by incomplete alveolar gas mixing and associated V/Q mismatching within the terminal respiratory units, temporal V/Q mismatching within units, spatial V/Q mismatching between units, and venous admixture. Most causes of VDphys are influenced by inspiratory flow pattern and the time available for gas diffusion and distribution. Analysis can be made from the single breath test for carbon dioxide (SBT--CO2) which is the plot of fraction of carbon dioxide in expired gas against expired volume. The common causes of VDalv are associated with a sloping SBT-CO2 phase III. Combination of SBT-CO2 with PaCO2 yields VDphys and VDalv. A sloping phase III with a negative arterial-end-tidal PCO2 gradient implies compensation by perfusion for early emptying, overventilated alveoli.

Breath Tests↗
PubMed1981

Prediction of the physiological dead space/tidal volume ratio during anaesthesia/IPPV from simple pre-operative tests.

It can be shown that the assumption of an arbitrary value for VDphys/VT during IPPV can lead to unacceptable degrees of hypo- or hyperventilation. We investigated 33 adult patients scheduled for major non-thoracic surgery, to see if any simple tests could be used to predict VDphys/VT during anaesthesia/IPPV. Fifteen were smokers and 18 non- or ex-smokers. The tests were spirometry, and the single breath tests for CO2 and for N2 (SBT-CO2: SBT-N2). Patients were ventilated during anaesthesia with a Servo Ventilator 900 B, and SBT-CO2 was recorded from a CO2 Analyzer 930. During anaesthesia/IPPV, smokers had significantly greater VDphys/VT (0.40 +/- 0.10 vs. 0.31 +/- 0.07 [P less than 0.01]), and they had more steeply sloping phase IIIs of SBT-CO2 (P less than 0.01) than non- and ex-smokers. For smokers, VDphys/VT was correlated to age (r = 0.75, P less than 0.01), to the slope of phase III of both SBT-CO2 and SBT-N2, and to the ratio of FEV% to its predicted value. For non- and ex-smokers, only one variable, efficiency, describing the shape of SBT-CO2, was correlated to VDphys/VT (r = 0.53, P less than 0.05). Pre-operative prediction of VDphys/VT based on age, smoking history, and SBT-CO2 can reduce the uncertainty in estimating VDphys/VT and therefore ventilatory requirements. It appears to offer the greatest benefits amongst smokers, who show a large variation in VDphys/VT.

Age Factors↗
PubMed1981

Conventional versus computer-aided interpretation of long-term ECG recordings--aspects of precision and economy.

In a sample of 60 12-h long-term ECG recordings we compared a computer-aided analysis method to a conventional scanning technique for diagnostic precision and time consumption. As regards diagnostic precision no significant difference between the methods could be found. Both were considered efficient in detecting episodes of arrhythmia. Using the computer-aided method a physician spent an average of 16 min on analyzing a recording and writing the diagnostic report. The conventional method required 69 min from an ECG technician and 9 min from a physician for each recording. From these figures we conclude that about 750 12-h recordings/year are required to outweigh the extra annual cost for the computer, if it is used only for long-term ECG analysis. If the computer can also be used for other purposes the system for long-term ECG analysis is profitable with a smaller annual number of recordings.

Adult↗
PubMed1981

Cyclofenil versus placebo in progressive systemic sclerosis. A one-year double-blind crossover study of 27 patients.

Cyclofenil was evaluated versus placebo in the treatment of progressive systemic sclerosis (PSS, scleroderma) in a 2 x 6-month double-blind crossover study. The mean duration of disease was six years. Of 38 patients entering the study, 27 completed both periods. Reasons for drop-outs were very high liver transaminases in three cases, cardiac death in two, and drug allergy, alcoholic problems, suspected congestive heart failure, reactivation of tuberculosis, arteriosclerotic heart disease, and lethal progression of PSS in one case each. No fatality was attributed to cyclofenil. Liver enzyme abnormalities were seen in 13 of 35 active drug periods and in 5 of 30 placebo periods. Cutaneous and visceral involvement were assessed by a large battery of subjective parameters and objective tests. Overall improvement was seen during 17 drug periods and nine placebo periods (N.S.), but a paired comparison of the status at the end of each treatment period resulted in the following distribution: 15 were improved at the end of the drug period, four at the end of placebo period (p less than 0.01) and eight were unchanged. In patients with a disease duration of five years or less, joint stiffness and pain were less on drug than on placebo treatment (p less than 0.05). In the whole group, oesophageal peristalsis improved (p less than 0.05). Blood folate increased (p less than 0.01). Working capacity was lower after the drug period than after the placebo period (p less than 0.05). Several other parameters, however, did not change significantly. Cyclofenil appears to be a promising drug in the treatment of PSS and should be tested further in controlled long-term studies.

Clinical Trials as Topic↗
PubMed1980

Continuous positive airway pressure: modes of action in relation to clinical applications.

Some physical effects of CPAP are discussed, as are the various devices used for CPAP in infants. Some of the controversies about CPAP may be related to the unsuitability of certain techniques. Use in hyaline membrane disease, extrathoracic and intrathoracic airway obstruction, congestion of overperfusion of the lungs in diseases of the heart and great vessels, apnea repetens of immaturity, and phrenic nerve palsy is presented.

Airway Obstruction↗
PubMed1980

Clinical studies of gas exchange during ventilatory support--a method using the Siemens-Elema CO2 analyzer.

We describe a new portable infra-red analyses for use with the Siemens-Elema Servo ventilator. The sensor head constitutes a Y-piece connecting the patient to the ventilator tubing, and gives instant carbon dioxide determination. It is based upon simple principles that can be realized with modern techniques, offering for instance freedom from interference by anaesthetic gases, and eliminating the need for calibration. A non-zero inspired carbon dioxide concentration interferes with the measurements. Integration of the carbon dioxide signal with the flow signal from the Servo ventilator yields data about carbon dioxide excretion, and additional calculation yields VD/VT if PaCO2 is known. The accuracy of determination of end-tidal carbon dioxide and carbon dioxide elimination was found to be adequate for research purposes, and that of VD/VT for clinical purposes. The device is considered to be of value in the operating theatre and intensive care unit, for monitoring, as a guide to ventilatory needs, and for the investigation of the magnitude and causes of increased deadspace.

Aged↗
PubMed1980

Evaluation of mechanical ventilation in newborn infants. I. Techniques and survival rates.

The short-term outcome with survival rate, causes of death and neonatal complications in a 6-year material comprising 253 infants treated with intermittent positive pressure ventilation (IPPV) in the neonatal period has been analyzed in relation to different primary disorders necessitating IPPV treatment. The total survival rate was 53%. For the different diagnoses the survival rates were: hyaline membrane disease (HMD) 41%, apnoea repetens of immaturity 85%, severe birth asphyxia 46% and septicemia 59%. The total rate of pneumothorax during IPPV was 15% but occurred more often in the HMD group (28%). Trends in survival rates over the study period are discussed as are measurements for improvements.

Asphyxia Neonatorum↗
PubMed1980

Evaluation of mechanical ventilation in newborn infants. II. Pulmonary and neuro-developmental sequelae in relation to original diagnosis.

The incidence of bronchopulmonary dysplasia (BPD) and neuro-developmental sequelae in 135 infants surviving intermittent positive pressure ventilation (IPPV) in the newborn period were studied in relation to primary disorders requiring IPPV. The rate of BPD increased over the 6-year study period in hyaline membrane disease survivors from 14% to 28%, but decreased in infants with apnoea repetens from 38% to 13%. Immaturity seemed to be one important factor for development of BPD. The incidence of neuro-developmental sequelae in IPPV treated infants fell from 22% to 13% over the years. In infants with birth weight below 1501 g the rate of neurological handicaps was 11%.

Airway Resistance↗
PubMed1980

Pulmonary mechanics, chest X-ray and lung disease after mechanical ventilation in low birth weight infants.

Pulmonary mechanics, chest X-ray and the incidence of clinical lung disease were studied in 41 low birth weight infants treated with intermittent positive pressure ventilation (IPPV) in the neonatal period. Shortly after IPPV most patients, irrespective of X-ray findings, had signs of lung damage reflected in low dynamic compliance or high pulmonary resistance. Both parameters, however, had a strong tendency towards normalization during the first year of life. Overdistention on chest X-ray was common at 6--12 months of age. Pneumonia and bronchitis were common during the first two years of life but subsided later on. Development of BPD or later respiratory disease were not correlated to treatment with high inspired oxygen concentrations but commonest in patients with hyaline membrane disease. The combined findings of pulmonary mechanics and chest X-ray shortly after IPPV were correlated to later clinical lung disease.

Bronchitis↗
PubMed1979

Consecutive study of early CPAP-application in hyaline membrane disease.

Continuous positive airways pressure (CPAP) has been applied with a face-chamber in 74 infants with hyaline membrane disease (HMD) before 10 h of age. The total survival rate was 91% and the complication rate of pneumothorax was low (5%). The incidence of long term developmental and neurological sequelae was also low (4%). Among the 19 surviving very low birth-weight (VLBW) infants below 1501 g, only one has shown neurological sequelae at follow-up examinations after 18 months to 3 years of age. The incidence of cerebellar hemorrhage was not higher in infants treated with the CPAP face chamber than in infants not receiving assisted ventilation. Bronchopulmonary dysplasia did not occur in any infant treated with CPAP face chamber only. The main advantages with the face chamber technique are: no disturbance of glottis function, no mucosal damage and tube obstruction, or sudden pressure drops, as seen with other modes of CPAP application. The face chamber technique is suitable for early application of CPAP in infants with HMD as it is efficient, without hazards, and easily applied.

Age Factors↗
PubMed1979

A universal way to evaluate the curve in rhinomanometry.

A new way to evaluate the curve of nasal airway resistance has been developed. With polar coordinates, all curves can be described. Also, tightly closed or wide open noses can be compared with angles. The method is of value in clinical as well as in scientific work, especially when dealing with statistics.

Airway Resistance↗
PubMed1976

Continuous postive airways pressure treatment by a face chamber in idiopathic respiratory distress syndrome.

Continuous positive airways pressure treatment by a face chamber in idiopathic respiratory distress syndrome. During a 3-year period 45 infants with idiopathic respiratory distress syndrome (IRDS) requiring ventilatory support were treated in the neonatal unit. Continuous positive airways pressure (CPAP) via the face chamber was applied as initial therapy in 39 infants and during weaning from initial intermittent positive pressure ventilation (IPPV) treatment in 5 infants, whereas 1 infant received IPPV only. Among the 39 infants initially treated with CPAP 9 required IPPV as well. The overall survival rate was 37/45 or 82%. Incapacity to hyperoxygenate while breathing 100% oxygen was the indication for CPAP while occurrence of apnoeic attacks was the indication for IPPV. Pao2 during the hyperoxia test before ventilatory support was less than 50 mmHg in 10 infants and between 50 and 105 mmHg in 35 infants. Surviving infants were followed up with neurological and developmental control examinations as well as chest x-ray, and in several infants pulmonary function tests. 3/37 infants had moderate neurological sequelae and only 1/37 infants developed bronchopulmonary dysplasia. No deleterious effects of the face chamber were seen. As the face chamber is a noninvasive and easily applied technique for CPAP therapy without hazards, it is proposed that it should be used at a still earlier stage of IRDS in order to lesson the need for IPPV treatment and to increase the neurological and lung functional quality of survival.

Cerebral Hemorrhage↗
PubMed1976

Computer classification of ST and T in averaged ECGs at rest and exercise.

A computer program for ST and T classification at rest and exercise is described. The automatic ST classification was based on the modification of the Minnesota code suggested by Punsar et al. The T wave classification was based on the Minnesota code of 1968. Recordings at rest, during and after exercise from 217 exercise tests were visually classified by two observers, and their result was compared to the computer's. Computer-observer comparisons yielded no more disagreements than between-observer comparisons. There were computer-observer disagreements caused by computer errors in 3% of the records. The repeatability of the computer's ST classification on records taken during exercise was better than that of one visual observer. Within-computer and within-observer repeatability appeared to be negatively affected by remaining noise in the average.

Adult↗
PubMed1976

A system for computer-assisted ECG recording at rest and exercise.

Great investments have been made in computerized ECG interpretation but little attention has been paid to rationalization of such costly activities as recording, labelling and mounting ECGs, and still less to the presentation of ECGs. A system for such tasks is described. It includes a PDP8/E computer and modified ink jet ECG recorders, which write alphanumeric text and function as analogue input- and output-devices for the computer. On-line computer service is given independently to two laboratories for ECG at rest, VCG or exercise ECG. After averaging the ECG signal, the computer writes out a properly labelled ECG in an easily surveyable form. The visual interpretation of the ECG is entered and is then written on a new sheet together with the averaged 12-lead ECG and a rhythm strip. In exercise testing, the computer records and processes the ECG at predetermined intervals. The processing includes an automatic ST classification. A summarized presentationof the ECG before, during and after exercise allows easy visual identification of ECG changes. Experience of the system has mainly been obtained from 2 years of routine exercise ECG recording and to a limited extent from ECG and VCG recording at rest.

Cardiology↗