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Biomedical subjects

W H Matthews

Publications and source records attributed to W H Matthews.

3 recordsLinked to original sources

Influence of spirometry and chest roentgenography on the management of pulmonary outpatients.

Spirometry and chest roentgenography are frequently employed to evaluate patients with respiratory problems. To determine their impact on the management of outpatients with lung disease, both tests were performed on 100 consecutive patients (40 men and 60 women; mean age, 52 +/- 15 years) who returned for reevaluation 16 +/- 9 weeks after their previous clinic visit. Patients with obstructive (n = 45), restrictive (n = 35), and mixed (n = 20) lung diseases were initially assessed by history and physical examination and classified clinically as improved, stable, or worse. A clinical management plan (CMP) was formulated based on this initial evaluation. Changes in the proposed CMP due to spirographic or roentgenographic results were then noted. None of the 19 patients who were clinically improved and only two (3%) of the 64 clinically stable patients had a change in CMP. In contrast, five (29%) of the 17 patients whose conditions deteriorated clinically had their proposed CMP modified after review of the spirograms and roentgenograms. Therapy was intensified in three of the seven patients whose CMPs were modified, while in the other four, treatment was withheld because results of both tests were unchanged. These results indicate that routine spirograms and chest films have little influence on the CMP of clinically stable patients. However, unexpected roentgenographic and spirometric findings frequently alter the management of the individual whose condition has clinically deteriorated.

Adult↗

Steady-state gas exchange in normothermic, anesthetized, liquid-ventilated dogs.

Anesthetized, paralyzed, purebred beagle dogs were ventilated for 45 min (n = 5) and 60 min (n = 5) with oxygenated (PIO2 = 685 mmHg) FC-80 fluorocarbon liquid at 38 degrees C. The PaCO2 remained constant at approximately 43 mmHg during 60 min of liquid ventilation (mean tidal volume = 290 ml, mean respiratory frequency = 2.8 breaths/min). The end-tidal PCO2 was consistently higher than PaCO2 during liquid ventilation. Histological examination by light as well as scanning electron microscopy of the lungs of dogs killed 10, 30, or 180 days after liquid ventilation revealed no pathological changes except for a slight increase in the number of macrophages, especially around the alveolar ducts. It is concluded that a steady state of gas exchange at near normal arterial carbon dioxide partial pressures can be maintained in anesthetized, normothermic dogs ventilated with FC-80 at respiratory frequencies of approximately 3 breaths/min.

Anesthesia↗

A fluorocarbon emulsion with a high solubility for CO2.

A stable emulsion can be prepared by subjecting a mixture of 30% (by volume) FC-80 fluorocarbon; a 0.3-M THAM solution titrated to pH 7.4 with HCl; and 0.04 g F68 Pluronic surfactant per milliliter FC-80 to ultrasonic energy. The emulsion has a density of 1.24 g/ml; and absolute viscosity of 2.4 centipoise; and an approximate fluorocarbon-droplet diameter of 3mu. The approximate CO2 content of the emulsion at partial pressures ranging from 30 to 60 mm Hg is 132 ml (STPD)/liter + (5.5 X PCO2). The O2 content in ml (STPD)/liter equals 0.213 X PO2 (mm Hg).

Carbon Dioxide↗