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Biomedical subjects

B E Smith

Publications and source records attributed to B E Smith.

At least 127 records · Page 7Linked to original sources
PubMed1987

Inhibitory effect of quinidine on plasma pseudocholinesterase activity in pregnant women.

The effect of quinidine at therapeutic and subtherapeutic concentrations on pseudocholinesterase activity in the plasma of 16 normal pregnant women was studied. The mean plasma pseudocholinesterase activity in the absence of quinidine (control) was 0.67 +/- 0.11 U/ml. The mean pseudocholinesterase activity in the presence of quinidine at concentrations of 0.5, 1.0, 2.0, and 5.0 micrograms/ml 0.48 +/- 0.09, 0.38 +/- 0.09, 0.29 +/- 0.10, and 0.19 +/- 0.09 U/ml, respectively. At therapeutic concentrations needed to treat cardiac arrhythmias (2 to 5 micrograms/ml), quinidine inhibited pseudocholinesterase activity by 60% to 70%. All the plasma samples had a normal dibucaine number (78 to 85). We recommend caution when succinylcholine and/or ester-type local anesthetics are used in pregnant women receiving quinidine.

Adolescent↗
PubMed1987

An acoustic model of the patient undergoing artificial ventilation.

The difficulty of applying conventional concepts of respiratory mechanics to high frequency ventilation (HFV) has so far inhibited its general acceptance by clinicians. The basis of an approach derived from an acoustic analysis of the ventilated patient is presented which may help to clarify the mechanism of action of HFV and offer some guidelines to its clinical application. The ventilator is considered as an acoustic source, and the patient's acoustic response to the ventilator is analysed. A response equation for the patient's respiratory system at low frequencies is derived, from which an expression for the fundamental resonant frequency is obtained. The high frequency acoustic response of the patient is examined with particular reference to the possibility of exciting multiple resonant modes within the airways. Following this, we have discussed the significance of the acoustic response and acoustic resonance in relation to gas exchange. It is suggested that these resonances may be used in adjusting indices of HFV in order to obtain optimum ventilation.

Acoustics↗
PubMed1987

Use of a low-power nerve stimulator during sciatic nerve block.

The use of a low-power nerve stimulator to aid nerve location during the performance of sciatic nerve block was compared with a conventional anatomically based technique. The success rate, both in terms of the production of an effective block and the duration of postoperative analgesia, was significantly higher in the stimulator groups than in the non-stimulator groups. The implications of the study for both clinical and teaching practice are discussed.

Anesthesia, General↗
PubMed1986

The nifH gene product is required for the synthesis or stability of the iron-molybdenum cofactor of nitrogenase from Klebsiella pneumoniae.

The MoFe protein of nitrogenase from Klebsiella pneumoniae contains an iron-molybdenum cofactor, FeMoco, the synthesis or processing of which involves the products of at least five genes, nifQ, nifB, nifN, nifE and nifV. We have detected FeMoco activity in extracts of strains which synthesise neither of the MoFe protein subunits, indicating that FeMoco can be synthesised prior to combination with the MoFe protein polypeptides. Expression of the nifH gene (or a large part of it), was essential for FeMoco activity to be observed either in the presence or in the absence of the MoFe protein subunits. The nifH gene product was not involved in the control of the transcription of other nif gene products known to be involved in FeMoco synthesis or processing, nor was it essential for the stability of performed FeMoco before its combination with the MoFe protein polypeptides.

Bacterial Proteins↗
PubMed1986

Aerodynamic characteristics of Blom-Singer low-pressure voice prostheses.

In vitro airflow resistance calculations were completed for 20 low-pressure voice prostheses (Blom-Singer). Total device resistances ranged from 63.51 to 105.91 cm H2O per liter per second (LPS), with an overall average resistance of 82.04 cm H2O/LPS. Resistance characteristics were compared with those of other commercially available devices.

Air Pressure↗
PubMed1986

Effect of normal and preeclamptic pregnancies on the oxyhemoglobin dissociation curve.

Hemoglobin affinity for oxygen in whole blood of ten normal nonpregnant women, ten normal pregnant women at first trimester, ten normal pregnant women at second trimester, 24 normal pregnant women at or near term, and 14 pregnant women with preeclampsia at or near term was studied. The mean P-50 values for normal nonpregnant women, normal pregnant women in first trimester, second trimester, and at or near term were 26.7 +/- 0.11 mmHg, 27.8 +/- 0.08 mmHg, 28.8 +/- 0.17 mmHg, and 30.4 +/- 0.20 mmHg, respectively. The mean P-50 of pregnant women with preeclampsia at or near term was 25.1 +/- 0.38 mmHg. It is concluded that in normal pregnant women there was a significant shift of P-50 to the right compared with the normal nonpregnant women (P less than 0.01), and the extent of this shift to the right is directly related to the duration of the pregnancy. In addition, preeclamptic parturients showed a significant shift of P-50 to the left when compared with normal pregnant women at or near term (P less than 0.001).

Analysis of Variance↗
PubMed1986

Distribution of evoked paraesthesiae and effectiveness of brachial plexus block.

The distribution of paraesthesiae evoked by a low power nerve stimulator during performance of supraclavicular brachial plexus block was studied in 120 patients. Evoked paraesthesiae in the distribution of the median nerve was associated with a significant improvement in effectiveness of the block when compared with evoked paraesthesiae in the ulnar and radial distributions. A possible explanation for this finding is proposed.

Adult↗
PubMed1986

Minitracheostomy: a new delivery system for jet ventilation.

Seventeen patients with respiratory failure from a variety of causes have been treated by high-frequency jet ventilation, delivered by a specially designed Y connector and a standard minitracheostomy tube, for periods ranging from 12 hours to 14 days. This percutaneous system provides access for full ventilatory support and tracheobronchial suction, but without the need for a cuffed endotracheal tube or sedation. Patients can eat, drink, and talk during ventilation. Ten of the patients were male and ages ranged from 31 to 77 years. Ventilation was satisfactory in 16 patients and unsatisfactory in one, who had also been difficult to manage on conventional ventilation. Thirteen patients resumed full spontaneous respiration and four died of their underlying disease while still being supported with a ventilator. These results suggest that the combination of minitracheostomy and high-frequency jet ventilation may offer significant advantages in the management of some patients with respiratory failure.

Adult↗
PubMed1985

Aerodynamic assessment of prosthetic speech aids.

The primary function of a speech aid prosthesis is to provide adequate palatopharyngeal function by preventing nasal emission and hypernasality during oral speech production and permitting sufficient nasal air escape during nasal consonant production. The adequacy of speech aids is often judged subjectively by speech-language pathologists and prosthodontists. However, when oral and laryngeal function are also affected, additional information may be needed for accurate assessment of palatopharyngeal function and optimal prosthetic management. In these instances, aerodynamic measurements can provide information about palatopharyngeal function and guide fabrication and modification of speech aid prostheses to provide adequate palatopharyngeal function for speech.

Air↗
PubMed1985

Aerodynamic assessment of the results of pharyngeal flap surgery: a preliminary investigation.

Voice-quality (i.e., nasality) judgments are commonly used to evaluate the results of pharyngeal flap surgery. However, these are subjective judgments of questionable validity and reliability. This project was designed to systematically evaluate the outcome of pharyngeal flap surgery utilizing objective, quantifiable physiologic (pressure-flow) information. Thirty-one patients who had undergone pharyngeal flap surgery were selected. Pressure-flow measurements and perceptual judgments of speech were obtained following surgery. Results indicated that using pressure-flow criteria, only 52 percent of the outcomes were considered successful. Results also indicated that 35 percent of the cases were characterized by substantial nasopharyngeal airway obstruction. In the present study, these findings, along with the related perceptual phenomenon of denasality, were considered unsuccessful. Finally, results suggest that aerodynamic measurements can be used to assess other surgical techniques designed to correct velopharyngeal insufficiency.

Adolescent↗
PubMed1985

The Penlon Bromsgrove high frequency jet ventilator for adult and paediatric use. A solution to the problem of humidification.

The Penlon Bromsgrove is a new high frequency jet ventilator, suitable for use in both adults and children. The jet stream is humidified by means of an integral in-line Bernoulli nebuliser. The self-recharging nebuliser can also convey drugs directly to the airways in the form of an aerosol. Alarms and fail-safe systems are incorporated. A pressure gauge continuously displays the jet drive pressure. There are two digital LED displays; one shows jet frequency in breaths per minute; the other, the jet drive pressure, minimum, maximum and mean patient airway pressures. Two fail-safe systems ensure that these pressures do not become excessive. Both audible and visual alarms are provided. The prototype has proved to be quiet and completely reliable over more than 4000 hours use, with no bronchoscopic or histological evidence of ineffective humidification.

Adult↗
PubMed1985

Modeled velopharyngeal orifice area prediction during simulated stop consonant production in the presence of increased nasal airway resistance.

This project examined modeled velopharyngeal orifice area estimation under conditions simulating voiceless stop consonant production in the presence of nasal airway obstruction. The results indicated that accurate estimates of velopharyngeal orifice area can be obtained using Warren's hydrokinetic equation during aerodynamic events like those known to exist during speech in the presence of increased nasal airway resistance. These findings provide support for clinical and research use of Warren's pressure-flow approach to investigate velopharyngeal function during speech production.

Airway Obstruction↗
PubMed1985

Predictions of modeled palatopharyngeal port openings under conditions simulating pharyngeal flap reconstruction.

This study examined the estimation of modeled palatopharyngeal orifice areas under conditions similar to those created by pharyngeal flap reconstruction. Results indicated that accurate estimates of the palatopharyngeal orifice area can be obtained using Warren's pressure-flow approach when the calculated area is actually the combined area of the lateral palatopharyngeal port openings. Our findings lend additional support to the view that pressure-flow techniques can provide objective information about the degree to which surgical procedures provide palatopharyngeal competence for speech.

Cleft Palate↗