Search PubMed⌕ Search

Biomedical subjects

A B Adams

Publications and source records attributed to A B Adams.

53 records · Page 3Linked to original sources
PubMed1992

Lung mechanics and gas exchange during pressure-control ventilation in dogs. Augmentation of CO2 elimination by an intratracheal catheter.

Increased awareness of pressure-related injury to the alveolar-capillary interface has renewed interest in modes of ventilation that limit alveolar distention such as pressure-controlled ventilation (PCV). We examined respiratory system mechanics and gas exchange during PCV in six dogs. Our data conformed to the predictions of our single-compartment mathematical model of respiratory dynamics during PCV (J Appl Physiol 1989; 67:1081-92). For a fixed pressure (Pset) and inspiratory time fraction (Tl/Ttot) (15 cm H2O and 0.3, respectively), minute ventilation (VE) reached a well-defined plateau as frequency (f) increased from 10 to 50 breaths/min and tidal volume (VT) fell progressively. Concomitantly, the physiologic dead-space fraction (VD/VT) increased from 0.50 +/- 0.04 to 0.85 +/- 0.04, and arterial PCO2 (PaCO2) rose from 39 +/- 4 to 76 +/- 12 mm Hg. At a fixed combination of frequency, applied pressure, and Tl/Ttot (40 breaths/min, 15 cm H2O, and 0.3), VE did not change when we introduced fresh gas continuously from an intratracheal catheter. However, PaCO2 and VD/VT fell progressively as catheter flow increased from zero to 14 L/min (60 +/- 12 to 40 +/- 12 mm Hg and 0.83 +/- 0.03 to 0.25 +/- 0.14 mm Hg, respectively). We conclude that during PCV at a fixed Pset and Tl/Ttot increasing frequency caused VT to fall and VE to reach a plateau. Declining VT was associated with a rise in PaCO2 because of a subsequent fall in alveolar ventilation. Insufflating fresh gas by an intratracheal catheter increased alveolar ventilation and improved CO2 elimination by washing out the anatomic dead space.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Tracheal gas insufflation during pressure-control ventilation. Effect of catheter position, diameter, and flow rate.

In the setting of acute lung injury, ventilatory strategies that adjust minute ventilation (VE) to achieve eucapnia often lead to alveolar rupture or damage. Tracheal gas insufflation (TGI) reduces the VE requirements of conventional mechanical ventilation by decreasing the effective dead-space fraction (VD/VT) of each breath. We studied the effect of catheter flow rate (Vcath) and position as well as catheter tip diameter and configuration on CO2 elimination during TGI-augmented pressure-controlled ventilation (PCV) in normal dogs. We studied three catheter positions (1, 5, and 10 cm above the carina) at Vcath of 2, 5, and 10 L/min (n = 6). When the catheter tip was positioned 1 cm above the carina, PaCO2 decreased significantly from a baseline (PCV alone) of 67 +/- 10 mm Hg to 52 +/- 11, 43 +/- 9, and 32 +/- 7 mm Hg (p < 0.05) at Vcath of 2, 5, and 10 L/min, respectively. For the same Vcath values, positioning the catheter tip 10 cm above the carina increased PaCO2 to 54 +/- 15, 46 +/- 12, and 40 +/- 11 mm Hg. Advancing the catheter tip 2 cm below the carina did not improve PaCO2 significantly (n = 3). At a catheter position of 1 cm above the carina and a Vcath of 10 L/min, changing the luminal inner diameter (1.5 versus 3.0 mm) or tip configuration (open tip versus occluded tip with two side holes) of the catheter did not change PaCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

An evaluation of MDI (metered dose inhaler) spacers and adapters: their effect on the respirable volume of medication.

The use of a metered dose inhaler (MDI) with an adapter or spacer designed to deliver medication to ventilated patients has been found to produce effects similar to those achieved with small volume nebulizers. For 9 commonly used MDI adapters or spacers, we measured and compared their production of available respirable volume (ARV) of medication. A simulated ventilator circuit was configured to determine ARV as measured by a laser particle-size counter. The adapters or spacers were grouped in three categories: chamber, in-line, and elbow styles. The devices were actuated into the circuit, and ARV was measured 36 separate times with various combinations of medication and medication canister. We found significant differences in ARV between devices, device categories, and medications as compared by ANOVA testing. In this study, chamber-style MDI devices produced greater respirable volume than the in-line- or the elbow-style devices. Of the chamber-style devices, the cone-shaped chamber device provided more respirable volume than did the other two chamber devices. We also found differences among the medications, although we did not anticipate such differences. The possible factors to explain medication differences were not investigated in this study. Because ARV differs according to the design of the individual device used, the choice of device may alter the respirable volume of the medication delivered and, therefore, the effectiveness of the prescribed medication. We conclude that to achieve the desired effects of the medication, practitioners may need to customize the number of MDI actuations according to the device in use.

Administration, Inhalation↗
PubMed1983

The guided design strategy in the biochemistry laboratory.

This article describes a nontraditional biochemistry laboratory course for first-year dental students. The course consisted of two laboratory exercises adapted to the guided design strategy and a short research project. The major advantage of the guided design laboratories was subjectively determined to be the development of problem-solving skills, which students previously enrolled in a traditional laboratory course seemed to lack. Students exposed to the guided design approach successfully applied these skills when performing their research projects. These students also reflected a better understanding of the biochemical principles encountered. The major disadvantages were the great amount of faculty time required to prepare the guided design materials and the reduced amount of subject matter covered. Student evaluation scores of the new laboratory program showed dramatic improvement over those for the traditional laboratories. In addition, students' attitudes toward the new biochemistry laboratories were more positive than those exhibited in the traditional course.

Biochemistry↗
PubMed1980

Estimated and determined P50 values in erythrocytosis.

Actual determination of the position of the oxygen-hemoglobin dissociation curve (P50) was compared to three methods of estimating P50 in 20 patients with erythrocytosis. There was a significant correlation between determined and estimated P50 values for each of the methods studied. Furthermore, four patients with high affinity hemoglobins were readily distinguished from the other patients by estimating P50. The data suggest that calculating P50 is reliable and may replace the need for actual measurement.

Adolescent↗
PubMed1976

The basic science curriculun problem in dental education: some causes and solutions.

At present there is no established purpose generally agreed on by members of the dental profession for the basic sciences in the dental curriculum. Such a purpose, supported by the entire profession, is considered a necessary first step in improving the basic science curriculum. Substantive basic science courses should be taught by instructors, holding a Ph.D. degree. These basic science instructructors, however, need the respect of the clinical faculty in order to be effective in teaching dental students. They also need to be given professional opportunity equal to that given clinical faculty if they are to commit themselves to dental education. The role of the clinical faculty in teaching the scientific basis of clinical methods is described, and the need for cooperation and communication between the basic science and clinical faculties is emphasized. Regularly scheduled faculty workshops are recommended for this purpose. A decrease in student contact time for clinical faculty is also suggested. The dental profession, led by dental educators, with advice from other health professionals, dental students, and the general public, is the logical body to define the purpose of basic science in dental education.

Curriculum↗
PubMedDate not supplied

The agar-replica technique for dental caries diagnosis. Has its time arrived?

The agar-replica technique of Bahn et al is described. This caries-diagnostic technique detects the site of lactobacillus infection on the teeth. Evidence and logic indicate that this technique is more accurate than current caries-diagnostic methods. The method appears to answer the recent call for diagnostic methods which identify the more subtle expression of the disease, and it helps classify lesions into categories keyed to different treatment strategies.

Agar↗
PubMedDate not supplied

Caries risk assessment.

Caries risk assessment is a relatively simple, yet cost effective method to evaluate the oral condition likely to produce carious lesions in both children and adults. This procedure can also indicate current caries activity in a patient. The assessment can provide the foundation for a scientifically-based preventive dental practice. The cost and contents of two different caries risk assessment kits are discussed.

Adolescent↗