Novel mathematical processing method of nocturnal oximetry for screening patients with suspected sleep apnoea syndrome.

Aim: Polysomnography (PSG) is the current standard for diagnosing sleep apnea syndrome (SAS). A reliable test would be useful to reduce the considerable resources required for PSG.

Methods: We developed a new mathematical analysis, which quantifies amplitude variations of pulse oximetry (SpO(2)) and heart rate (HR) throughout the night, allowing measurement of the total time in which ΔSpO(2) >4% and presented as a new oximetric index ventilatory hypoxemic index (VHI).

Use of thoracic impedance sensors to screen for sleep-disordered breathing in patients with cardiovascular disease.

Screening patients for the possibility of sleep apnoea, one of the most common forms of sleep-disordered breathing, requires measurement of respiration. We propose a simple method to estimate the amplitude modulation of a respiratory tidal volume, using a semi-quantitative measure of respiration based on thoracic impedance (TI). Because respiratory volume changes may be accommodated by varying displacements of the rib cage (RC) and abdomen (AB), the latter produced by outward motion of the diaphragm, it is necessary for any useful measure of respiration to be closely related to both RC and AB displacements.

[Epidemiology and delays in the management of 355 patients with lung cancer].

Background: The epidemiology of patients with lung cancer in a Seine-Saint-Denis hospital are reported, as well as causes of diagnostic and therapeutic delays in their management.

Material And Methods: Retrospective analysis of cases diagnosed from January 1, 1997 to December 31, 2003.

Results: Of 355 cases, 15.

Scaling behavior in beta-wave amplitude modulation and its relationship to alertness.

We performed an experimental study of beta waves occurring in human electroencephalographic signals obtained from six healthy subjects that were monitored during the performance of a task requiring attention to auditory signals. We use wavelet analysis to study whether the fluctuations in the modulation of the beta-wave amplitude related to an indirect measurement of alertness. We found that these fluctuations exhibit a power-law behavior.

Inspiratory fall in systolic pressure in normal and asthmatic subjects.

We used a noninvasive monitor of arterial pressure to determine whether respiratory changes in arterial pressure were closely correlated with airflow obstruction in asthmatic patients during bronchial challenge with methacholine. To validate the noninvasive measurement of respiratory changes in arterial pressure, a preliminary study in 6 subjects with normal cardiovascular and respiratory systems was done during cardiac catheterization for suspected coronary artery disease. There were no significant differences between inspiratory falls in systolic pressure measured noninvasively and those measured from intraaortic pressure.

Comparison of thoracoabdominal calibration methods in normal human subjects.

In 19 normal subjects in the supine posture, we compared accuracy and precision of calibration methods that utilized different ranges of tidal volumes and thoracoabdominal partitioning: spontaneous quiet breathing (QB), isovolume maneuvers, and voluntary efforts to breathe with variable tidal volume and thoracoabdominal partitioning. Thoracic and abdominal movements were measured with the respiratory area fluxometer. Calibration methods utilizing one or more types of respiratory efforts were applied to three measurement situations: QB, variable breathing (volume and thoracoabdominal partitioning), and simulated obstructive apnea (isovolume efforts).

Asynchronous chest wall movements during non-rapid eye movement and rapid eye movement sleep in children with bronchopulmonary dysplasia.

The aim of this study was to assess whether age-related changes in thoracic shape modify patterns of thoracoabdominal asynchrony (TAA) or applicability of phase angle analysis during sleep in young children with increased respiratory loads. We assessed TAA during polysomnographic monitoring in 14 young children (mean age 32 months, range 19 to 46; mean weight 12.5 kg, range 9.

Bronchoconstriction-induced hyperinflation assessed by thoracic area measurement in guinea pigs.

The changes in end-expiratory lung volume (EELV) accompanying histamine-induced bronchoconstriction were compared for two routes of drug administration in anesthetized, paralyzed, and mechanically ventilated guinea pigs. Changes in EELV were estimated from measurements of thoracic cross-sectional area, assessed from the voltage induced by an external uniform magnetic field in a pickup coil encircling the rib cage. Increasing doses of histamine were administered as bolus injections in Group 1 (n = 7) and as nebulizations in Group 2 (n = 7).

Accuracy of respiratory inductive plethysmography during wakefulness and sleep in patients with obstructive sleep apnea.

To assess the accuracy of the respiratory inductive plethysmograph (RIP) during sleep in obese patients with obstructive sleep apnea (OSA), we monitored 13 patients with OSA during wakefulness and nocturnal sleep with simultaneous measurements of tidal volume from RIP and integrated airflow. Patients wore a tightly fitting face mask with pneumotachograph during wakefulness and sleep. Calibrations were performed during wakefulness prior to sleep and compared with subsequent wakeful calibrations at the end of the study.

Kinetics of action of salbutamol inhaled from a metered dose inhaler (MDI) and a "Diskhaler".

In a double-blind cross-over study, 12 patients with reversible airways obstruction were treated with 200 micrograms salbutamol base in aerosol or 400 micrograms of powder following methacholine-induced bronchoconstriction. Salbutamol was inhaled either from a conventional metered dose inhaler (MDI) or from an inhaler (Diskhaler) utilizing the powdered form of the drug. The efficacy of both forms was identical whether assessed in terms of FEV1 or vital capacity.

Respiratory cross-sectional area-flux measurements of the human chest wall.

A new device that utilizes the voltages induced in separate coils encircling the rib cage and abdomen by a magnetic field is described for measurement of cross-sectional areas of the human chest wall (rib cage and abdomen) and their variation during breathing. A uniform magnetic field (1.4 X 10(-7) Tesla at 100 kHz) is produced by generating an alternating current at 100 kHz in two square coils, 1.

What does inductance plethysmography really measure?

Inasmuch as it has been claimed that inductance plethysmography can measure cross-sectional area changes, we tested this assumption. We present experimental and computed relationships between self-inductance (L) of coils and areas (A) included inside for a coil with a well-defined side wavy pattern (triangular or sinusoidal) and for a real belt (Respitrace) placed on elliptical or rectangular configurations. The results are applied to the physiological field using measurements obtained from a computed tomography experiment.

Improvement of diaphragmatic function by a thoracic extradural block after upper abdominal surgery.

The effects on diaphragmatic function of a thoracic epidural block were assessed in 13 patients after upper abdominal surgery (UAS). Lung volumes and tidal changes in chest wall circumferences and gastric (delta Pgas) and esophageal (delta Pes) pressures were measured pre- and postoperatively. Volume displacement of the abdomen divided by tidal volume (delta VAB/VT) and delta Pgas/delta Pes were taken as indices of the diaphragmatic contribution to tidal breathing.

Evaluation of the end-expiratory lung volume as an indirect index of bronchial constriction in asthma.

The purpose of this study was to evaluate the merits of the end expiratory lung volume as an indirect ventilatory index of bronchial obstruction and to show an application of continuous monitoring of lung volume in asthmatic patients. The accuracy of the external measurements (IS) of functional residual capacity (FRC) was controlled by comparing them with the helium measurements (DS) obtained during nine methacholine tests (IS = 0.06 + 1.

Ventilatory pattern and chest wall mechanics during ketamine anesthesia in humans.

The effects of anesthetic doses of ketamine (iv bolus of 3 mg X kg-1 followed by a continuous infusion of 20 micrograms X kg-1 X min-1) on functional residual capacity (FRC) measured by the helium dilution method and on the breathing pattern recorded by a noninvasive method (NIM) based on chest wall circumference changes were studied in 14 ASA P.S. I patients.

Evaluation of differential linear transformers as a non-invasive ventilatory method in supine subjects.

We present a new method to measure thoraco-abdominal perimeter variations using differential linear transformers inserted in belts. The high sensitivity (250 mV/mm), the low time drift (1 mV/24 h compared to a 1 V output for a tidal volume), the good frequency response (up to 10 Hz) and low cost (12,000 FF) are the major advantages over other devices. After calibration (using change contribution of thorax and abdomen and the least square method for calculation of volume-motion coefficients), estimated tidal volumes in 23 adults in supine position are within 0.

Factors influencing pulmonary volumes and CO2 elimination during high-frequency jet ventilation.

An external spirometric method using a differential linear transformer was used to measure tidal volume (VT) and to determine factors influencing CO2 elimination and HFJV-induced "PEEP effect" in 15 critically ill patients under HFJV. VT increased with increasing driving pressure (DP) and decreasing frequency (f) and was influenced little by changes in I/E ratio. CO2 elimination, as reflected by the measurement of PaCO2, was mainly influenced by the absolute level of VT rather than by the product VT X frequency (PaCO2 = 5715/VT, r = 0.

Diaphragm dysfunction induced by upper abdominal surgery. Role of postoperative pain.

The effects of upper abdominal surgery on diaphragmatic function were studied in 5 patients. During quiet tidal breathing, the volume displacement of the abdomen within the tidal volume (Vab/Vt) and the ratio of abdominal and transdiaphragmatic pressure changes (delta Pab/delta Pdi), taken as an index of the diaphragmatic contribution to the breathing process, decreased significantly on the first postoperative day (p less than 0.001); in 2 patients, a cephalad paradoxical motion of the diaphragm during inspiration was observed.