PubMed Health⌕ Search

Biomedical subjects

D Stănescu

Publications and source records attributed to D Stănescu.

At least 19 recordsLinked to original sources
PubMed1991

Pattern of simulated snoring is different through mouth and nose.

Cineradiography of the pharynx during simulated snoring was done in 6 healthy volunteers, and supraglottic pressure and flow rate were recorded in 12 others. We observed, immediately before snoring, a decrease in the sagittal diameter of the oropharynx followed, during snoring, by high-frequency oscillations of soft palate and pharyngeal walls. The pattern of soft palate oscillations was different while snoring through the nose or mouth. During inspiratory snoring through the nose, the soft palate remained in close contact with the back of the tongue and only the uvula presented high-frequency oscillations. Snoring through the mouth resulted in ample high-frequency oscillations of the whole soft palate. Frequency of airflow and supraglottic pressure oscillations was less (P less than 0.05) during mouth (28.2 +/- 7.5 Hz) than during nasal snoring (77.8 +/- 36.7 Hz). This difference may be related to the smaller oscillating mass (i.e., uvula) during nasal snoring. At variance with our previous data, which showed that snoring during sleep, in both heavy (nonapneic) snorers and obstructive sleep apnea patients, was systematically preceded by flow limitation, this was not true during simulated snoring.

Adult↗
PubMed1990

Hypopharyngeal and neck cross-sectional changes monitored by inductive plethysmography.

We present a method to assess cross-sectional area (CSA) changes of the extrathoracic airways (EA) by using an inductive plethysmograph (IP) band placed around the upper part of the neck. Measurements of mouth pressure (Pm) (or flow rate, V) and neck CSA changes during respiratory efforts against a high (or infinite) resistance have shown a highly significant relationship between Pm changes (or V changes, respectively), reflecting CSA changes of the EA and CSA changes of the neck. Simultaneous measurements of CSA of the neck (by IP) and of EA (by computerized tomography) during sustained inspiratory and expiratory efforts against a closed airway showed a high correlation between changes in the former and latter structures. Changes in CSA of the neck were larger with positive than negative transmural pressures, in keeping with the known larger compliance of this airway during expiration. We found this method helpful to assess the behavior of the EA during obstructive apnea episodes, hypopneas, and snoring.

Adult↗
PubMed1989

Reassessment of the interruption technique for measuring flow resistance in humans.

We have previously produced evidence that, in patients with obstructive lung disease, compliance of extrathoracic airways is responsible for lack of mouth-to-alveolar pressure equilibration during respiratory efforts against a closed airway. The flow interruption method for measuring respiratory resistance (Rint) is potentially faced with the same problems. We reassessed the merits of the interruption technique by rendering the extrathoracic airways more rigid and by using a rapid shutter. We measured airway resistance (Raw) with whole body plethysmography during panting (at 2 Hz) and Rint during quiet breathing. Rint and Raw were expressed as specific airway (sGaw) and interruptive conductance (sGint), respectively. In nine healthy subjects (cheeks supported), sGint (0.140 +/- 0.050 s-1.cmH2O-1) was lower (P less than 0.02) than sGaw (0.182 +/- 0.043 s-1.cmH2O-1). By contrast, in 12 patients with severe obstructive lung disease (forced expiratory volume in 1 s/vital capacity = 41.0 +/- 19.8%), sGint (0.058 +/- 0.012 s-1.cmH2O-1) was higher (P less than 0.05) than sGaw (0.047 +/- 0.007 s-1.cmH2O-1), when the cheeks were supported. When the mouth floor was also supported, average values of sGaw (0.048 +/- 0.008 s-1.cmH2O-1) and sGint (0.049 +/- 0.014 s-1.cmH2O-1) became similar. In conclusion, we confirm previous findings in healthy subjects of higher values of Rint, with respect to Raw, probably because of differences in glottis opening between quiet breathing and panting. In airflow obstruction, supporting both the cheeks and the mouth floor decreased sGint, which became similar to sGaw.

Adult↗
PubMed1988

Head position modifies upper airway resistance in men.

We measured in healthy volunteers airway resistance (R(aw)), resistance of the respiratory system (Rrs), and supralaryngeal resistance (Rsl) in the following head positions: neutral, extended, and partially and fully flexed. Sagittal magnetic resonance images of the upper airways were recorded in neutral and flexed head positions. We observed significant increases in Raw (P less than 0.01), Rrs (P less than 0.001), and Rsl (P less than 0.001) in the flexed position, with respect to the neutral one, and corresponding decreases of specific airway and specific respiratory conductances. Resistances decreased (although not significantly) when the subjects' heads were extended. A decrease in both diameter and surface area of the hypopharyngeal airways (as shown by magnetic resonance images) with total head flexion was accompanied by significant increases in all measured resistances. Changes in the caliber of hypopharynx appear to be responsible for the increase in resistance during head flexion.

Adult↗
PubMed1979

Frequency dependence of respiratory resistance in healthy children.

We measured in 130 (61 girls) children aged 3--14 yr respiratory resistance (Rrs), with the oscillation technique, between 4 and 9 Hz. Rrs, at both 4 and 9 Hz, decreased as a function of height (r = 0.74, P less than 0.001). No statistical difference was found between boys and girls. Frequency dependence of resistance (Rrs 4 Hz-Rrs 9 Hz) was found in children at all ages, and decreased with increasing height (r = 0.50, P less than 0.001). We suggest that frequency dependence of resistance in children can be explained on the basis of an increased peripheral resistance, which produces an asynchronous distribution of tidal volume between dead space and lung parenchyma. During growth peripheral resistance decreases and Rrs bcome less frequency dependent to reach at about 15--16 yr independency of frequence.

Adult↗
PubMed1977

Difference between the He bolus and N2 technique for measuring closing volume.

We measured closing volume in sixteen healthy subjects simultaneously and separately with a bolus of He (using a rapid catharaometer) and with the N2 technique. In another group of 35 active workers (some with airway obstruction), closing volume was measured separately with those two methods. In both groups the He closing volume was significantly higher than the N2 closing volume. We attribute this difference to a less marked vertical N2 concentration gradient, leading to a less clearly defined separation between phase III and IV and resulting in an underestimation of the N2 closing volume. Indeed, increasing the N2 gradient in the lung, by inspiring O2 from a higher than residual volume level, increased the N2 closing volume which became comparable to the He closing volume. We also found, for both He and N2 tracings, a significant between-observers difference in reading of the closing volume. However, the difference in reading of ts difference in reading of the closing volume. However, the difference was less important for He closing volumes. We conclude that the bolus method improves the resolution of closing volume and decreases the interobserver variability.

Adult↗
PubMed1976

Evaluation of lung function indices for bronchodilator trials. Results of a cross-over study of fenoterol.

In 10 patients with airway obstruction, spirographic indices and maximal expiratory flow rates were measured before inhalation of fenoterol and at different time intervals, for 5 h, following the inhalation of 200 mug of this substance. 10 min after inhalation of fenoterol, there was a statistically significant increase in all lung function indices. A further increase was observed later. 3 h after inhalation of fenoterol, all indices were still significantly higher than control values. No side effects were observed. At all time intervals, the increase of the forced expiratory volume in 1 sec (FEV1.0), peak expiratory flow rate (PEFR) and maximal expiratory flow rate at 50 and 75% of the vital capacity reached a similar level of statistical significance. It is concluded that for the trial of the bronchodilator drugs, any of these indices may be used, and for practical purposes FEV1.0 and PEFR are best suited.

Adult↗