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Biomedical subjects

M Darowski

Publications and source records attributed to M Darowski.

28 records · Page 2Linked to original sources
PubMed1995

Assessment of respiratory system compliance by a flow recording method.

Standard methods for the assessment of the compliance of the respiratory system require recordings of both airway pressure and ventilatory volume. A method based on the recording of respiratory flow only, with no need of measuring airway pressure was reported some years ago. The purpose of the present study was to test a modification of this flow-recording technique. The technique is based on the measurement of inspiratory flow with and without the addition of a source of external compliance added to the inspiratory circuit. The difference in inspiratory flow between these two situations can be used to derive the compliance of the respiratory system. The method was and in patients with acute respiratory failure, and compared with a standard method based on airway pressure and inspiratory gas flow recording. Model experiments showed strong correlation between the new flow-recording method and the standard method (r = 0.99, P < 0.001) with a coefficient of variation of less than 2% with both methods. In patients with acute respiratory failure, the flow and standard methods gave similar results when no end-inspiratory pause was applied (mean difference 5 +/- 40 ml/kPa (x +/- s.d.)). The standard method gave significantly higher compliance values, different from the flow method, when an end-inspiratory pause of 10% was applied (mean difference 53 +/- 2 ml/kPa, P < 0.01). The flow method was not influenced by the use of an end-inspiratory pause.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Anaesthesia and mucopolysaccharidoses. A review of airway problems in children.

The airway problems encountered during anaesthesia in all children with mucopolysaccharidoses presenting for a surgical procedure from 1988 to September 1991 are reviewed. Thirty-four patients underwent 89 anaesthetics for 110 procedures. The results reveal a high incidence of airway problems. The overall incidence of difficult intubation was 25% and failed intubation 8%. In those children with Hurler's syndrome, the difficult intubation incidence was 54% and failed intubation incidence 23%. Other potential anaesthetic problems such as cardiac anomalies and obstructive sleep apnoea are also reviewed.

Adolescent↗
PubMed1991

Pain relief after tonsillectomy in adults: intramuscular diclofenac and papaveretum compared.

A wide variety of surgical and pharmacological methods have been described in an attempt to reduce pain after tonsillectomy, with conflicting results. Opiates are still widely used, despite unwanted side-effects. Recently the non-steroidal anti-inflammatory drugs have been shown to be effective against a variety of post-operative pains. Diclofenac is effective in both children and adults in the relief of pain after tonsillectomy when administered rectally, but absorption is variable, and suppositories are not widely accepted in the UK. The present double-blind study compared a single intramuscular dose of diclofenac with papaveretum in adults undergoing tonsillectomy. Post-operatively, the patients who received diclofenac had less pain and started drinking significantly sooner than the control group. There were no undesirable side-effects. Intramuscular diclofenac is superior to papaveretum in the relief of pain in adults undergoing tonsillectomy.

Adolescent↗
PubMed1985

Development and evaluation of a flow-dividing unit for differential ventilation and selective PEEP.

Differential ventilation with selective positive end-expiratory pressure (PEEP) was studied in a two-compartment lung model, using one ventilator and a flow-dividing unit consisting of inspiratory flow resistors and an inspiratory threshold valve. The compliance of each lung compartment was varied between 0.15 and 0.23 1 X kPa-1 and the resistance was varied from 0 to 3.5 kPa X 1(-1) X s. The minute volume was 12 1 and the respiratory frequency 12/min, with an inspiratory:expiratory ratio of 1:2. An even distribution of ventilation to the two lung compartments was obtained with the inspiratory flow resistors or the threshold valve under all conditions studied. However, a stepwise increase in the inspiratory resistance of one lung compartment from 1.0 to 2.5 or from 2.5 to 3.5 kPa X 1(-1) X s required readjustment of the inspiratory flow resistor to achieve an even distribution of ventilation, whereas the inspiratory threshold valve needed no readjustment. Large differences in the inspiratory impedance of the two lung compartments caused asynchronous gas delivery when the ventilation distribution was adjusted by means of the flow resistors. Use of the threshold valve resulted in synchronous gas delivery. The flow-dividing unit consists of non-active elements and can thus be connected to any ventilator.

Humans↗
PubMed1985

A new method for calculating total respiratory system compliance. Theory and model experiments.

A new method for calculating total respiratory system compliance is described, based on simple modelling of a ventilator-respiratory system circuit that assumes linear characteristics of the circuit parameters compliances and resistances. The method requires only that flow measurement be conducted continuously to obtain compliance, if the internal compliance of the circuit is known beforehand. Model experiments showed that the compliance of a child test lung, calculated from the flow recording, differed at most by 10% from the compliance obtained by separate measurements of pressure and volume under static conditions, over a wide range of respiratory flows and airway resistances.

Child↗
PubMed1984

Practical aspects of differential ventilation with selective peep in acute respiratory failure.

Hypoxaemia in association with acute respiratory failure continues to be a severe problem in some intensive care patients. Among strategies proposed, we want to focus attention on differential ventilation with selective PEEP, administered in the lateral position. This ventilation technique has proved successful in the treatment of refractory hypoxaemia due to severe bilateral lung disease. The rationale of this concept is briefly presented in this paper, where the main emphasis is laid on the practical aspects of its clinical application. Two case reports are included as examples of our experiences.

Acute Disease↗
PubMedDate not supplied

Ventricular energetics during mechanical ventilation and intraaortic balloon pumping--computer simulation.

Computer simulation of a cardiovascular system enabled us to predict the effects of simultaneous application of mechanical ventilation (MV) and intraaortic ballon pumping (IABP) on ventricular energetics. External work (EW), pressure-volume area (PVA), potential energy (PE) and cardiac mechanical efficiency (CME) were calculated. Nummerical simulation showed that changes of positive intrathoracic pressure have a considerable effect on left and right ventricular EW, PE, PVA and CME, whether IABP is used or not. The right ventricular energetics was much less influenced by systemic resistance (Ras) changes than the left ventricular one. Simultaneous application of IABP and MV showed a remarkable effect on left ventricular EW. The net result was reversed sensitivity to pulmonary resistance (Rap) and reduced sensitivity to Ras. PVA was generally reduced, while CME is increased by simultaneous presence of IABP and MV. The sensitivity of CME to Rap and Ras variation was diminished in this situation.

Computer Simulation↗
PubMedDate not supplied

Energetic parameter changes with mechanical ventilation in conjunction with BVAD assistance.

The aim was to assess the influence of a biventricular assist device (BVAD) on ventricular energetics parameters (external work, oxygen consumption, cardiac mechanical efficiency) for both ventricles, when mechanical ventilation was applied. The experiments were performed using a computer simulator of cardiovascular system (CARDIOSIM) after modelling a pathological state of the left ventricle (E(v)Left = 0. 9 mmHg cm(-3) and increasing pulmonary resistance (Rap = 0.3 mmHg cm(-3 s). The effect of mechanical ventilation was mean intrathoracic pressure changes from 0 to +5 mmHg. This simulation showed that application of BVAD for both ventricles reduces external work and that this effect is stressed by positive intrathoracic pressure, reduces cardiac mechanical efficiency that is quite insensitive to intrathoracic pressure and increases oxygen consumption, which is reduced by positive intrathoracic pressure. The increase of potential energy at the onset of BVAD evidences a rightwards shift of ventricular work cycle (unloading of the ventricles). In general, positive intrathoracic pressure during BVAD assistance adversely affects ventricular energetics.

Biomedical Engineering↗