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Biomedical subjects

D E Olson

Publications and source records attributed to D E Olson.

At least 19 recordsLinked to original sources
PubMed1998

Acoustic and perceptual evaluation of laryngeal reinnervation by ansa cervicalis transfer.

OBJECTIVES/HYPOTHESIS: To evaluate the acoustic and perceptual results of laryngeal reinnervation with ansa cervicalis to recurrent laryngeal nerve anastomosis. STUDY DESIGN: Retrospective study of voice samples from 12 patients with unilateral recurrent laryngeal nerve paralysis, treated with ansa cervicalis to recurrent laryngeal nerve anastomosis. Samples were recorded before surgery and at least 8 months after surgery. METHODS: The samples were subjected to several acoustic analyses sensitive to paralytic dysphonia, including cepstral peak prominence, noise-to-harmonics ratio, and measures of frequency and amplitude perturbation. The voice samples from the patients were randomized with age- and sex-matched samples from normal subjects and judged by trained listeners for overall dysphonia, roughness, breathiness, asthenia, and strain. The preoperative and postoperative results were compared statistically, and the postoperative results were compared with the matched normal subjects. RESULTS: As a group, the patients showed improvement (P < .05) in cepstral peak prominence, frequency perturbation, and perceptual judgments of overall dysphonia, breathiness, and asthenia. The best results occurred in patients with isolated vocal fold paralysis. The postoperative group as a whole did not improve to the level seen in matched normals. Suboptimal results were seen primarily in patients with untreated laryngeal or extralaryngeal pathology beyond the laryngeal paralysis. CONCLUSIONS: These data suggest that laryngeal reinnervation has the potential to bring about a return to normal or near-normal voice in patients with isolated unilateral vocal fold paralysis.

Acoustics↗
PubMed1997

Quantitative RT-PCR measurement of cytochromes p450 1A1, 1B1, and 2B7, microsomal epoxide hydrolase, and NADPH oxidoreductase expression in lung cells of smokers and nonsmokers.

Bronchial epithelial cells (BEC) are the progenitors of bronchogenic carcinomas and are exposed to polycyclic aromatic hydrocarbon (PAH) procarcinogens through inhalation of combustion products. PAH are converted to carcinogenic molecules through a combination of monoxygenation by cytochrome p450 (CYP) enzymes in the presence of NADPH oxidoreductase (OR) and hydrolysis by microsomal epoxide hydrolase (mEH). In artificial systems, the relative expression of these genes determines whether carcinogenic or noncarcinogenic species are generated during metabolism. This relationship was explored in humans by using quantitative competitive reverse transcriptase polymerase chain reaction amplification to determine the range of expression of CYP1A1, CYP1B1, mEH, and NADPH OR in BEC recovered from 10 nonsmokers and 9 smokers. CYP2B7 expression was evaluated because, although little is known of its substrate specificity, it is expressed at high levels in human lung tissue. CYP1A1 and CYP1B1 were expressed in BEC at significantly different levels (P < 0.05) in the 9 smokers at 1.4 +/- 2.3 x 10(4) and 2.4 +/- 3.2 x 10(3) molecules/10(6) beta-actin molecules (mean +/- STD), respectively, but each was measurable in only one of the 10 nonsmokers. There was significant inter-individual variation (P < 0.05) in both CYP1A1 and CYP1B1 expression among the subjects for whom sufficient data were obtained. The inducibility of human BEC CYP1A1 gene by PAH exposure was confirmed in vitro by incubating cultured immortalized human BEC with beta-naphthoflavone and observing a > 6-fold induction of CYP1A1 after 24 h. In contrast to BEC, alveolar macrophages expressed CYP1A1 at low (30-70 molecules/10(6) beta-actin molecules) to unmeasurable levels in both smokers and nonsmokers. There was no significant difference in expression of mEH, CYP2B7, or NADPH OR in smokers compared with nonsmokers. The inter-individual variation in absolute and relative expression of PAH metabolism enzymes in BEC reported here supports the hypothesis that inter-individual variation in ability to activate/inactivate inhaled PAH carcinogens accounts for at least some of the inter-individual variation in risk for bronchogenic carcinoma.

Adult↗
PubMed1992

Physical models of the smaller pulmonary airways.

Any internalized flow exhibits closely coupled interactions with its confining geometry. Efforts to gain an understanding of in vivo airway transport phenomena, therefore, dictate that careful attention to be paid to those anatomic airway features that constrain and modify regional air movement. We present a series of analyses of human small airway casts to refine and extend the current geometric description of small airway bifurcations. Airway shape factors believed to have a high propensity to alter the fluid dynamics of airflows within this region are specifically addressed. The results of these anatomic and fluidic analyses are used to develop two average symmetrical and asymmetrical bifurcation patterns. Finally, methods for the production of physical bifurcation models conforming to these requirements are presented to develop a rational representation of anatomic as well as flow similitude during airway research.

Adult↗
PubMed1990

Quantifying ventilatory reserve to predict respiratory failure in exacerbations of COPD.

We developed a concept of VR in patients with acute exacerbation of advanced COPD and tested the hypothesis that it is predictable and clinically useful in the ER. Our concept of VR was based on the idea that a threshold VF and a MSV capacity are measurable; ie, VR = MSV - VF. We measured resting minute ventilation, the 15-s MVV, FEV1 and ABG values in 13 patients with exacerbation of COPD in the ER and 11 stable subjects with similar degrees of COPD. We tested if measures of VR could distinguish between ER patients progressing to respiratory failure, ER patients who avoided progression to respiratory failure and stable patients. There were significant differences in measures of the mean VR between various groups of patients. We conclude that in this COPD population, VR can be accurately predicted in the ER and that it may be a clinically valid predictor of patient outcomes.

Aged↗
PubMed1987

Reversible and irreversible components of central-airway flow resistance.

The flow energy loss (head loss) through a cast of canine central airways is found to be nearly independent of flow direction. By contrast, head loss in geometrically-simpler branching sections at comparable flow conditions is highly irreversible, with inspiratory loss being greater by nearly two units of dynamic pressure (2 X 1/2 rho V2). In these branching sections head loss appears to be independent of important geometric parameters such as the branch length/diameter ratio and the exit/inlet flow-area ratio. An analysis of these observations suggests that kinetic energy factors, not shear stresses, account for most of the energy dissipated in central airways and in simple bifurcating sections. Inspiratory loss in bifurcations is greatly increased by the onset of flow separation: irreversibility is minimal in central airways, where separation either is absent or else is much less pronounced.

Airway Resistance↗
PubMed1987

Compliance measure development and assessment of theophylline therapy in ambulatory patients.

The objectives of this study were: (a) to develop a drug serum level-based compliance measure which incorporated pharmacokinetic analysis of patient and drug parameters and to compare it to refill records, an indirect measure, and (b) to use that measure to determine whether pharmacist consultation increased compliance. Sixty adult, male chronic obstructive pulmonary disease out-patients who received theophylline were randomly assigned to one of two groups with counselling provided to experimental-group patients only. Compliance was measured by the ratio of actual serum theophylline level to that predicted by pharmacokinetic estimation and by the number of refills in 155 days. More experimental-group patients had actual levels within both +/- 10% and +/- 20% of predicted levels (P = 0.0006 and 0.04). They also obtained more refills than control patients (P = 0.05). The pharmacokinetically based serum level measure appeared to be the more useful measure for identifying non-compliance, which suggests that it is of greater value than existing measures. In addition, the results suggest that comprehensive consultation by a clinical pharmacists can improve compliance with theophylline therapy in the out-patient setting.

Adult↗
PubMed1984

A pulsed wire probe for the measurement of velocity and flow direction in slowly moving air.

This report describes the theory and operation of a pulsed-probe anemometer designed to measure steady three-dimensional velocity fields typical of pulmonary tracheo-bronchial airflows. Local velocities are determined by measuring the transport time and orientation of a thermal pulse initiated at an upstream wire and sensed at a downstream wire. The transport time is a reproducible function of velocity and the probe wire spacing, as verified by a theoretical model of convective heat transfer. When calibrated the anemometer yields measurements of velocity accurate to +/- 5 percent and resolves flow direction to within 1 deg at airspeeds greater than or equal to 10 cm/s. Spatial resolution is +/- 0.5 mm. Measured flow patterns typical of curved circular pipes are included as examples of its application.

Biomedical Engineering↗
PubMed1981

Complications and consequences of endotracheal intubation and tracheotomy. A prospective study of 150 critically ill adult patients.

A prospective study of the complications and consequences of translaryngeal endotracheal intubation and tracheotomy was conducted on 150 critically ill adult patients. Adverse consequences occurred in 62 percent of all endotracheal intubations and in 66 percent of all tracheotomies during placement and use of the artificial airways. The most frequent problems during endotracheal intubation were excessive cuff pressure requirements (19 percent), self-extubation (13 percent) and inability to seal the airway (11 percent). Patient discomfort and difficulty in suctioning tracheobronchial secretions were very uncommon. Problems with tracheotomy included stomal infection (36 percent), stomal hemorrhage (36 percent), excessive cuff pressure requirements (23 percent) and subcutaneous emphysema or pneumomediastinum (13 percent). Complications of tracheotomy were judged to be more severe than those of endotracheal intubation. Follow-up studies of survivors revealed a high prevalence of tracheal stenosis after tracheotomy (65 percent) and significantly less after endotracheal intubation (19 percent)(p < 0.01). Thirty-nine of 41 (95 percent) patients with endotracheal intubation and 20 of 22 (91 percent) patients with tracheotomy had laryngotracheal injury at autopsy. Ulcers on the posterior aspect of the true vocal cords were found at autopsy in 51 percent of the patients who died after endotracheal intubation. There was no significant relationship between the duration of endotracheal intubation or tracheotomy and the over-all amount of laryngotracheal injury at autopsy, although patients with prolonged endotracheal intubation followed by tracheotomy had more laryngeal injury at autopsy (P = 0.06) and more frequent tracheal stenosis (P = 0.05) than patients with short-term endotracheal intubation followed by tracheotomy. Adverse effects of both endotracheal intubation and tracheotomy are common. The value of tracheotomy when an artificial airway is required for periods as long as three weeks is not supported by data obtained in this study.

Adolescent↗
PubMed1980

Comparison of direct and acoustical area measurements in physical models of human central airways.

Total cross-sectional areas were computed from direct measurements made on two human central airway casts. Acoustic pulse-response measurements were obtained on rigid-walled positive replicas of these casts. From the acoustic response data of each cast, we computed the area-distance function of the acoustically equivalent structure (i.e., the structure with regular branching and negligible viscous losses, but with similar acoustic properties). The acoustic data predicted equivalent areas that compared favorably to the total cross-sectional areas in the casts at all points from the beginning of the trachea to distances about 6 cm beyond the carina corresponding to airways of the third, fourth, or fifth generation. These results indicate that, at least in the central airways, branching asymmetry and internal energy losses introduced negligible errors in estimates of cross-sectional areas derived from acoustic pulse-response measurements. This rapid noninvasive technique thus shows promise as a method of detecting upper and central airway obstruction.

Acoustics↗