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Biomedical subjects

J B Vonwiller

Publications and source records attributed to J B Vonwiller.

13 recordsLinked to original sources

Epidermolysis bullosa--a review of 15 years' experience, including experience with combined general and regional anaesthetic techniques.

Eight patients with epidermolysis bullosa received a total of 60 anaesthetics for 67 procedures over the fifteen-year period 1972 to 1986. On twenty-three occasions patients were intubated. On thirteen occasions general anaesthesia was supplemented by regional blockade, involving a total of thirty-four local anaesthetic blocks. Complications from intubation were minimal and none were seen related to regional blockade.

Anesthesia, Conduction↗

The Stocks suction bullet.

The Stocks suction bullet is a device allowing maintenance of positive pressure ventilation, continuous distending pressure and high inspired oxygen concentrations during tracheal toilet in intubated patients. The effectiveness of this device was studied using an experimental apparatus and a dummy lung to represent neonates being treated with either C.P.A.P. or I.P.P.V. and P.E.E.P. By using appropriate combinations of suction catheter type and size, bullet lumen size, ventilator settings and suction pressure limit, it was possible to maintain during suctioning ventilation peak pressures between 50% and 100% of presuction levels and continuous distending pressures (P.E.E.P. or C.P.A.P.) at or in excess of 80% of presuction levels.

Airway Obstruction↗

Measurement errors in pneumotachography due to pressure transducer design.

When pneumotachography is used during intermittent positive pressure ventilation (IPPV), the design of some differential pressure transducers can cause measurement errors. These errors may be avoided by using differential pressure transducers which have small, equal chambers free from temperature sensitive electrical elements. Few of the transducers which are sensitive enough for clinical use fulfil these requirements.

Diagnostic Errors↗

Evaluation of etidocaine in extradural block.

Etidocaine has been evaluated in extradural block with regard to its absorption, toxicity and clinical effectiveness, which have been compared with those of bupivacaine. Etidocaine is associated with lower plasma concentrations than bupivacaine and its absorption is decreased by the addition of adrenaline 1:200,000 to a greater extent than is the case with bupivacaine. Etidocaine causes motor paralysis more frequently than does bupivacaine, especially if adrenaline is added. The duration of action of the two drugs is similar when comparing etidocaine 1% and bupivacaine 0.5%. Bupivacaine 0.75%, however, acts for a significantly longer time than etidocaine 1%. The drug is a useful addition to the range of local anaesthetics, especially with regard to the degree of motor blockade it can achieve during surgical procedures.

Acetanilides↗

Evaluation of infant ventilators.

A method of evaluating the performance of paediatric ventilators under simulated clinical conditions is described, together with the results of this evaluation of the prototypes of two ventilators designed specifically for use with infants and small children.

Airway Resistance↗

Errors in pneumotachography with intermittent positive pressure ventilation.

Instrument errors that can occur when pneumotachography is used during Intermittedt Positive Pressure Ventilation (IPPV) have been described previously (Kafer 1973). Our efforts to eliminate these errors led to the discovery of further inaccuracies, which appear to be due to the design of the differential pressure transducers used with pneumotachograph head. A system was used in which a sine-wave pump delivered a constant tidal volume to a dummy lung, the tidal volume being measured by means of a pneumotachograph. Using Grass, Statham and Devices differential pressure transducers, the volume recorded as leaving the dummy lung was consistently greater than that recorded as entering, and changing the pneumatic polarity of the differential pressure transducer produced large differences in the recorded volume. In some cases the error was greater than the volume being measured. There would seem to be several causes of such errors. The Sanborn 270 differential pressure transducer and the Greer micromanometer appeared to be free of these artifacts. The results of this study throw into doubt much previously published work using pneumotachography during IPPV.

Equipment and Supplies↗