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Biomedical subjects

D Hess

Publications and source records attributed to D Hess.

At least 163 records · Page 9Linked to original sources
PubMed1991

Compression volume in adult ventilator circuits: a comparison of five disposable circuits and a nondisposable circuit.

UNLABELLED: Although the concept of ventilator circuit compression is well known, it is not fully appreciated clinically. We compared the compression volume of five adult disposable ventilator circuits and a nondisposable circuit. METHODS: Five brands of disposable circuits (Inspiron, Intertech, Marquest, Seamless, and U-Mid) and one nondisposable brand (Bennett) were used. The circuits were attached to the outlet of a Bennett MA-1 ventilator in the standard manner, and the filter and humidifier were bypassed to eliminate their contribution to compression volume. The ventilator delivered 1 L of gas to a Michigan Instruments Test Training Lung at a flow of 60 L/min and a rate of 12/min. A valve system was placed between the Y-connector and the TTL to partition circuit compression volume from the volume delivered to the test lung. The compression factor was calculated by dividing the compression volume by the ventilating pressure. Five compliance settings were used on the TTL (0.1, 0.05, 0.03, 0.02, and 0.015 L/cm) to simulate different ventilating pressures. Pressure at the Y-connector, compressible volume, and volume delivered to the TTL were measured using a calibrated Timeter RT200 volume-pressure analyzer. Five measurements were made with each brand. A new circuit was used for each run with a disposable circuit, and a different circuit from the respiratory care department stock was used for each run with a nondisposable circuit. RESULTS: There were significant differences between the compression factors at different TTL compliance settings (p less than 0.001), and brands of circuits evaluated (p less than 0.001). There was a significant interaction effect for compression factors between TTL compliance setting and circuit brands (p less than 0.001). The compression factors for all disposable circuits were greater than the compression factors for the nondisposable circuits (p less than 0.05). CONCLUSIONS: There were differences in circuit compression factors as a function of the ventilating pressure and the brand of circuit. Although these differences are too small to be clinically important in many cases, they may be important during ventilation with low tidal volumes and high pressures.

Adult↗
PubMed1991

Noninvasive respiratory monitoring during ventilatory support.

Noninvasive monitoring is commonly used during ventilatory support. This monitoring includes pulse oximetry, capnography, transcutaneous monitoring, monitoring of respiratory mechanics, and indirect calorimetry. There are advantages and disadvantages to each of these forms of monitoring and the technical ability to use each of them must be balanced against clinical usefulness.

Blood Gas Monitoring, Transcutaneous↗
PubMed1991

Simultaneous determination of retinol, tocopherols, carotenes and lycopene in plasma by means of high-performance liquid chromatography on reversed phase.

The determination of the vitamins A and E as well as of carotenes and lycopene is important for studies of cardiovascular diseases and cancer. A method for laboratory routine is reported to separate simultaneously retinol, tocopherols, alpha- and beta-carotene, lycopene and beta-cryptoxanthin in human plasma or serum by HPLC on reversed phase starting from one extract. Two detectors with programmable wavelength are used sequentially, a spectrophotometer for the detection of the carotenoids in the visible region and a fluorometer for the assay of retinol and the tocopherols.

Carotenoids↗
PubMed1990

Bean pathogenesis-related (PR) proteins deduced from elicitor-induced transcripts are members of a ubiquitous new class of conserved PR proteins including pollen allergens.

We have searched for induced transcripts in a cDNA library derived from bean cell supension cultures treated with an elicitor from Colletotrichum lindemuthianum. Six independently isolated cDNAs corresponding to rapidly induced small mRNAs have been classified by their DNA sequence and slightly different induction behaviour into two groups. 5'- and 3'-untranslated regions exhibit little similarity, but the deduced small acidic proteins designated PvPR1 and PvPR2 are 89% identical. No relationship was found with the well-characterized PR1 proteins from tobacco. However, the PvPR proteins are closely related to pI49 in pea (64% identity), pSTH2 in potato (41% identity) and PcPR1-1 in parsley (39% identity), which are also induced in response to elicitor or microbial attack. Moreover, a major pollen allergen in birch (BetvI) has a 44% identity with PvPR1 proteins. These similarities establish a ubiquitous class of conserved defense-related proteins and suggest a common yet still unknown function. Southern blot analysis indicates that PvPR protein gene organization is highly complex with an estimated copy number of more than 12 genes.

Amino Acid Sequence↗
PubMed1990

Prehospital administration of inhaled metaproterenol.

STUDY OBJECTIVES: We conducted a study of the prehospital use of inhaled metaproterenol. DESIGN, SETTING, TYPE OF PARTICIPANTS, AND INTERVENTIONS: Advanced life support (ALS) providers were trained with a standardized curriculum to identify patients likely to benefit from prehospital inhaled metaproterenol administration. Unit doses of metaproterenol were used in a small-volume nebulizer. We prospectively included 122 patients in an initial study (71 men; age, 63 +/- 19 years) to evaluate the safety and effectiveness of metaproterenol in the field, and 150 patients (including the original 122) in an additional study to evaluate patient selection criteria. MEASUREMENTS AND MAIN RESULTS: The treatments resulted in an increase in peak flows, a decrease in respiratory rates, and no change in heart rates. In 62% of patients, the increase in peak flow exceeded 15%. Wheezing improved in 59% of the patients, worsened in 4%, and did not change in the remainder. Air entry by auscultation improved subjectively in 59% of patients. Mild tremor occurred in 8% of patients, moderate tremor occurred in 1%, and no tremor occurred in the remainder. Significant dysrhythmias did not occur. CONCLUSIONS: ALS providers correctly identified patients for this therapy. No technical problems were encountered in the field with this treatment approach. We conclude that ALS providers can be taught to identify patients likely to benefit from inhaled metaproterenol, that inhaled metaproterenol can be administered in the field, and that metaproterenol is both safe and effective when used in the prehospital setting.

Administration, Inhalation↗
PubMed1990

An evaluation of volumes delivered by selected adult disposable resuscitators: the effects of hand size, number of hands used, and use of disposable medical gloves.

UNLABELLED: Due to increasing concern over potential cross-infection during cardiopulmonary resuscitation (CPR), a number of disposable resuscitators have become commercially available. The wearing of disposable medical gloves by persons performing CPR has also become commonplace. In this study, we evaluated the effects of hand size, use of disposable medical gloves, and number of hands used (one versus two) on the volumes delivered by five adult disposable resuscitators. METHOD: Persons familiar with bag-valve ventilation were recruited to participate in the study--eight with small hands, eight with medium hands, and eight with large hands. Ventilation was delivered to one side of a Vent-Aid training test lung (TTL), and volumes were measured with a BEAR VM-90. In random order, each participant ventilated the TTL with all combinations of one hand/two hands, gloves/no gloves, and each of the following resuscitators: Code Blue, Hospitak, Pulmanex, Mercury, and Ambu SPUR. The participants were instructed to ventilate the TTL as they would ventilate a patient. RESULTS: The mean =/- SD volumes (in liters) were small hands = 0.68 +/- 0.15, medium hands = 0.71 +/- 0.18, large hands = 0.81 +/- 0.19 (p=0.006); gloves = 0.73 +/- 0.19, no gloves = 0.73 +/- 0.18 (p=0.80); one hand = 0.62 +/- 0.12, two hands = 0.84 +/- 0.17 (p less than 0.0001); Code Blue = 0.79 +/- 0.14, Hospitak = 0.56 +/- 0.11, Pulmanex = 0.71 +/- 0.15, Mercury = 0.77 +/- 0.18, SPUR = 0.83 +/- 0.2 (p less than 0.0001). CONCLUSIONS: The use of gloves did not significantly affect volume delivery. Delivered volumes did increase significantly as hand size increased and as number of hands used to squeeze the bag increased, and observed differences in volume delivery between brands of resuscitators may be clinically important in some cases. This study emphasizes the importance of squeezing the resuscitator with two hands during bag-valve ventilation.

Adult↗
PubMed1989

Evaluation of mouth-to-mask ventilation devices.

UNLABELLED: A number of mouth-to-mask ventilation devices have become commercially available in the past several years. In this study, we compared the volumes delivered by eight of these devices to the volumes delivered by mouth-to-mouth ventilation. METHOD: Fourteen respiratory care practitioners participated in the study. Ventilation was delivered to an adult resuscitation manikin. Each subject ventilated the manikin using mouth-to-mouth technique and each of the following mouth-to-mask devices: Boehringer EVA, Hospitak, Hudson, Intertech Safe Response, Laerdal Pocket Mask, Life Design Systems (LDS), Respironics SealEasy, and Vital Signs. Evaluation periods of 1 minute were used, minute ventilation and respiratory rate were measured, and tidal volume was calculated. RESULTS: There was a significant difference between the volumes delivered by the masks (p less than 0.001). The volumes delivered by each mask were less than mouth-to-mouth volumes (p less than 0.05 in each case). The mean +/- SD mouth-to-mouth volume was 1.04 +/- 0.32 L. The mean +/- SD volumes for each of the devices was 0.54 +/- 0.34 L for the EVA, 0.77 +/- 0.21 L for the Hospitak, 0.51 +/- 0.26 L for the Hudson, 0.81 +/- 0.35 L for the Safe Response, 0.65 +/- 0.25 L for the Pocket Mask, 0.82 +/- 0.27 L for the LDS, 0.79 +/- 0.32 L for the SealEasy, and 0.76 +/- 0.21 L for the Vital Signs. CONCLUSIONS: We found considerable variability between the volumes delivered with commercially available mouth-to-mask ventilation devices. Although the volumes delivered during mouth-to-mask technique were less than those delivered with mouth-to-mouth technique, the volumes delivered by some of the mouth-to-mask devices were large enough to allow them to be substituted for mouth-to-mouth technique.

Equipment Design↗