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Biomedical subjects

J Popovich

Publications and source records attributed to J Popovich.

At least 55 records · Page 3Linked to original sources
PubMed1986

Mechanical ventilation. Physiology, equipment design, and management.

The major goals of mechanical ventilation are the prevention of significant respiratory acidosis and the correction of arterial hypoxemia. Ventilators are categorized as negative- or positive-pressure types, depending on their effect on airway pressure. Positive-pressure ventilators, which are used in the treatment of acute respiratory failure, may be subclassified as pressure-, volume-, or time-cycled. Volume types provide stable tidal volumes and inspiratory oxygen concentrations over the range of changing ventilatory conditions seen in acute respiratory failure. Ventilation may be provided in a number of modes. No clear-cut advantage of intermittent mandatory ventilation over assisted mechanical ventilation has been demonstrated. By following simple guidelines, the clinician can initiate mechanical ventilation that provides an ideal ventilatory pattern.

Acidosis, Respiratory↗
PubMed1986

Lack of bacterial aerosols associated with heat and moisture exchangers.

Contaminated condensate might serve as a source for cross infection. Heat and moisture exchangers (HME) are devices that humidify inspired gases, which pass through a hygroscopic felt pad surrounded by a cellulose sponge housed in a plastic case. In our study, we used a Servo 150 HME in place of a cascade humidifier in mechanical ventilator circuits. We performed 2 studies to evaluate the microbiologic safety of the HME. First, 42 HMEs used by patients for 24 h were tested in the laboratory for contamination. To simulate patient/air exchange, the HMEs were connected to the Andersen Sampler (flow at 35 L/min x 20 min). Although the inner felt pad of the HMEs was contaminated in 74% of the units (31 of 42), only 4.8% (2 of 42) generated 1 to 2 bacteria/702 L of air. In a second study, HMEs contaminated with either Staphylococcus aureus or Pseudomonas aeruginosa (at 10(3), 10(5), or 10(8) organisms/ml) were connected to an Andersen Air Sampler to simulate a ventilator circuit. Bacterial aerosols were not generated, with the exception of 2 to 4 bacteria recovered after contamination with 10(8) bacteria. The HME can provide humidification for mechanically ventilated patients with little risk of generating respirable bacterial aerosols.

Aerosols↗
PubMed1986

Evaluation of premixed intravenous theophylline loading doses.

We evaluated the use of a standard protocol utilizing premixed theophylline containers in comparison to traditional intravenous aminophylline loading doses in 19 critically ill adults. Blood samples were obtained immediately before and after 30-minute infusions of aminophylline and theophylline bags. Aminophylline loading doses were calculated to the exact mg/kg and were delivered as such. Calculation of the theophylline loading dose used a simplified protocol that uses doses rounded to the nearest 100 mg. Comparison of the relative performance of the two loading dose methods was evaluated by computing mean squared prediction errors and root mean squared errors. The two methods were not statistically different when evaluated by a matched pair t-test. We conclude that use of a standard protocol that rounds theophylline doses to the nearest 100mg results in peak theophylline concentrations not significantly different from those predicted.

Aged↗
PubMed1985

Alterations in theophylline protein binding in acutely ill patients with COPD.

We investigated the role of decreased theophylline protein binding as a possible explanation for observed decreases in total theophylline concentrations (TC) in acutely-ill patients (AIP). Multiple blood samples were obtained from nine AIP with underlying chronic obstructive pulmonary disease (COPD) and from 13 stable COPD patients. The mean albumin concentration +/- SD was 2.7 +/- .61 mg/dl in the AIP vs 4.0 +/- 0.52 mg/dl in the stable COPD patients (p less than 0.005). Total (TC) and unbound theophylline concentrations (UTC) were determined. Theophylline protein binding was assessed at room temperature by centrifugal ultrafiltration of the patients' sera. The TC was 13.7 +/- 4.8 micrograms/ml in the stable COPD patients vs 11.8 +/- 4.1 micrograms/ml in the AIP although the mean dose was larger (17.21 +/- 5.41 vs 10.7 +/- 4.09 mg/kg/day of theophylline) in the AIP (p less than 0.005). There was no difference in UTC between the two groups (7.4 +/- 2.5 micrograms/ml and 8.1 +/- 2.6 micrograms/ml); however, the unbound fraction was higher in the AIP (p less than 0.005). We conclude that theophylline protein binding appears altered in AIP and that the altered binding relates predominantly to the severity of the clinical illness.

Acute Disease↗
PubMed1984

Hemophilus influenzae pneumonia in the adult. Radiographic appearance with clinical correlation.

Hemophilus influenzae septicemia is an important cause of life-threatening pneumonia in an immunocompromised patient. Eleven cases proved by blood culture were analyzed. Multilobar involvement with lobar or segmental consolidation and pleural effusion were common radiographic findings, but there were no signs of lobar expansion, bulging fissures, or cavitation. In general, predisposing factors such as alcoholism and chemotherapy place patients at risk. Radiographic response to therapy is variable but often lags behind clinical improvement.

Adolescent↗
PubMed1982

Diagnostic accuracy of multiple biopsies from flexible fiberoptic bronchoscopy. A comparison of central versus peripheral carcinoma.

We studied 46 patients, 26 with central visible tumors and 20 with peripheral nodules (in these, biplane fluoroscopic guidance was used), to determine the optimal number of forceps biopsies necessary to establish a diagnosis of carcinoma with the flexible fiberoptic bronchoscope. Overall yield was 96% (25 of 26) for central tumors and 75% (15 of 20) for peripheral nodules, using the combination of forceps biopsies and brushings. The combination of cytologic examinations plus one forceps biopsy produced a 92% diagnostic accuracy for central visible tumors. However, for central tumors the maximal diagnostic yield was not achieved until the fourth forceps biopsy, and for peripheral lesions accuracy continued to increase through the sixth forceps biopsy, and for peripheral lesions accuracy continued to increase through the sixth forceps biopsy in this study. Theoretically, as many as 10 biopsies may be necessary to maximize diagnostic yield for peripheral carcinomas.

Biopsy↗
PubMed1981

Differential lung ventilation with a modified ventilator.

To achieve synchronized differential pulmonary ventilation, an Ohio 560 ventilator was modified through separation of the outputs of the deep breath bellows and the tidal volume bellows and providing independent volume, flow rate, PEEP, oxygen-humidification, and alarm systems. The described ventilator modification is simple, inexpensive, and does not alter the performance characteristics of the original unmodified ventilator. Differential lung ventilation may be more easily achieved with this modified ventilator than with the simultaneous use of two ventilators or external electronic synchronizers.

Forced Expiratory Flow Rates↗