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PubMed1975

Progressive pulmonary insufficiency and other pulmonary complications of thermal injury.

Progressive pulmonary insufficiency appears to be a universal response to the lung to a variety of injuries which damage the pulmonary-capillary emdothelium. Persistent hyperventilation, unresponsive to the administration of oxygen, is the earliest clinical sign of this complication of trauma and should prompt close monitoring of pulmonary function (measurement of arterial blood gas and pH levels, Vd/Vt A-aDo2, minute ventilation, vital capacity and inspiratory force) to assess the severity of the disease, the need for mechanical ventilatory support and the effectiveness of treatment. Other pulmonary complications of burn injury range from carbon monoxide poisoning and narcotics overdosage in the immediate postburn period through marked hyperventilation directly related to burn size occurring in the absence of significant parenchymal change to later occurring hematogenous and airborne pneumonia. Inhalation injury, a chemical tracheobronchitis which significantly increases the mortality of a given-sized burn, may be present immediately postburn but clinically inapparent for 48-72 hours. 133Xenon lung scans permit early diagnosis of this pulmonary injury and the timely institution of a graduated therapeutic response keyed to the severity of pulmonary disability. Knowledge of the pathogenesis of each of these complications is requisite for the physician caring for burn patients and permits the employment of rational preventive and therapeutic measures.

Burns↗
PubMed2000

[Improvement in inspiratory muscle function in patients with mitral stenosis after percutaneous mitral valvuloplasty. Preliminary communication].

BACKGROUND: It has been proved that there is an inspiratory muscle dysfunction in mitral stenosis; Although its causes still remain unknown. AIM: To evaluate the effect of percutaneous balloon mitral valvuloplasty (PMV) on inspiratory muscle performance (IMP) in patients with mitral stenosis (mitral area < 1.5 cm2). PATIENTS AND METHODS: We studied IMP in 8 patients (35 +/- 10 years) before and 3 months after successful PMV. Inspiratory muscle strength was studied by measuring maximal statistical inspiratory mouth pressure (MIP). Endurance was evaluated using a two minute incremental threshold loading test in order to obtain the maximal sustainable inspiratory pressure (SIP), with the maximal sustainable load (MSL) the patients could sustain for 2 minutes. RESULTS: Mitral valvuloplasty increased mean cardiac index from 3.1 +/- 0.3 to 4.15 +/- 0.3 l/min/m2 (p < 0.01), and significantly decreased mean pulmonary and capillary pressures. The MIP value(118 +/- 6 cmH2O), similar to that of normal group, increased to 137 +/- 7 cmH2O (p < 0.01). SIP and maximal sustainable load were 52 +/- 3 cmH2O and 294 +/- 29 g respectively, lower than normal subjects (p < 0.05). They increased after PMV to 80 +/- 3 cmH2O and 463 +/- 26 g respectively (p < 0.001). CONCLUSIONS: PMV improved inspiratory muscle function in patients with severe mitral stenosis, probably secondary to a decrease work of breath and improvement of ventricular function.

Case-Control Studies↗
PubMed2000

Combination of inhaled nitric oxide therapy and inverse ratio ventilation in patients with sepsis-associated acute respiratory distress syndrome.

Inverse ratio ventilation (IRV) is a ventilatory technique that uses an inspiratory to expiratory ratio (I:E) greater than 1:1. We studied the effects of mechanical ventilation with an I:E of 1:3, 1:1, and 2:1 on arterial oxygenation in 10 patients with sepsis-associated acute respiratory distress syndrome (ARDS). At each I:E, patients received 0 and 4 ppm of inhaled nitric oxide (INO) in random order for 30 min. Respiratory and cardiovascular parameters were measured. Of the 10 patients studied, 7 responded to IRV and 3 did not. An increase in the I:E and the addition of INO significantly improved arterial oxygenation in the responders (p < 0. 0001 and p < 0.006, respectively). The combination of an increase in the I:E and INO had an additive effect on arterial oxygenation. The combined use of IRV and INO is a more effective method of avoiding hypoxemia than either INO or IRV alone.

Administration, Inhalation↗
PubMed2001

[Peak inspiratory flow using 2 different inhalers and a new portable device].

BACKGROUND: Inhaled medication through dry powder inhalers is widely used in children, but pediatric studies focussing on the ages at which these devices can be used are sparse. OBJECTIVE: To establish the difference in peak inspiratory flow (PIF) through Accuhaler and Turbuhaler in healthy children using a new device, In-check, and to determine the differences between the two different models of this device. METHODS: PIF was measured in 64 healthy male children (mean age 11.2 years, range 8.8-14.7) by means of In-check and In-check Dial using Accuhaler and Turbuhaler resistances. The best attempt of three was chosen. Height,weight, and forced expiratory volume in 1 second were also measured. RESULTS: Significant differences in PIF were found between the two inhalers: PIF In-check Accuhaler-PIF In-check Turbuhaler (134.4 +/- 15.5 L/min vs 99.9 6 +/- 11.1 L/min; p<0,000) and PIF In-check Dial Accuhaler-PIF In-check Dial Turbuhaler (109.6+/-10.5 L/min vs 86.8+/-8.9 L/min; p<0.000). The best correlation obtained among the different In-check measurements was between In-check Ac-cuhaler and In-check Turbuhaler (r=0.88; p<0.001), and the worst was between In-check Dial Accuhaler and In-check Turbuhaler (r =0.71; p<0.001). CONCLUSIONS: PIF through Accuhaler is significantly higher than that through Turbuhaler, although in both cases PIF was sufficient to provide adequate distribution of the inhaled medication in children aged 9-14 years. Consequently, in children younger than 9 years old, and especially during an asthma attack, In-check should be tried in order to discover whether the child is capable of using Turbuhaler correctly.

Adolescent↗
PubMed2001

[Selective training of respiratory muscles in patients with chronic heart failure].

BACKGROUND: Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance. AIM: To assess the effects of selective training of respiratory muscles in patients with heart failure. PATIENTS AND METHODS: Twenty patients with stable chronic heart failure, aged 58.3 +/- 3 years with an ejection fraction of 28 +/- 9%, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30% of maximal inspiratory pressure (PImax) in 11 and in 10% of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training. RESULTS: Both training loads were associated to an improvement in dyspnea (+2.7 +/- 1.8 and +2.8 +/- 1.8 score points with 30% PImax and 10% PImax respectively), maximal oxygen uptake (from 19 +/- 3 to 21.6 +/- 5 and from 16 +/- 5 to 18.6 +/- 7 ml/kg/min with 30% PImax and 10% PImax respectively, p < 0.05), PImax (from 78 +/- 22 to 99 +/- 22 and from 72 +/- 34 to 82.3 cm H20 with 30% PImax and 10% PImax respectively), sustained PImax (from 63 +/- 18 to 90 +/- 22 and from 58 +/- 3 to 69 +/- 3 cm H20 with 30% PImax and 10% PImax respectively), and maximal sustained load (from 120 +/- 67 to 195 +/- 47 and from 139 +/- 120 to 192 +/- 154 g with 30% PImax and 10% PImax respectively). The distance walked in 6 min only increased in subjects trained at 30% PImax (from 451 +/- 78 to 486 +/- 68 m). CONCLUSIONS: Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure.

Breathing Exercises↗
PubMed2001

Evaluation of inspiratory rise time and inspiration termination criteria in new-generation mechanical ventilators: a lung model study.

INTRODUCTION: Inspiratory rise time adjustment during pressure ventilation and inspiration termination criteria adjustment during pressure support ventilation are available on some of the newest mechanical ventilators. Both are designed to improve patient-ventilator synchrony. However, the function of these adjuncts during pressure ventilation on these ventilators has not been evaluated. METHODS: Three inspiratory rise times (minimum, medium, and maximum) were evaluated in 5 new-generation mechanical ventilators (Hamilton Galileo, Siemens 300A, Puritan Bennett 840, BEAR 1000, and Dräger Evita 4) during pressure support and pressure assist/control. Three inspiration termination criteria settings (minimum, medium, and maximum) were also evaluated in 2 mechanical ventilators (Hamilton Galileo and Puritan Bennett 840) during pressure support. All evaluations were performed with a spontaneous breathing lung model (compliance 50 mL/cm H2O, resistance 8.2 cm H2O/L/s, respiratory rate 12 breaths/min, inspiratory time 1.0 s, and lung model peak inspiratory flow 60 L/min). Throughout the evaluation, inspiratory pressure was set at 15 cm H2O and positive end-expiratory pressure at 5 cm H2O, resulting in a peak airway pressure of 20 cm H2O. RESULTS: Significant (p < 0.05) and important (> 10%) differences were found among the ventilators at similar rise times (minimum, medium, and maximum) and for each ventilator as rise time was varied. Also, significant (p < 0.05) and important (> 10%) differences were observed between ventilators and within each ventilator when inspiration termination criteria were varied. There were significant (p < 0.05) differences between pressure support and pressure assist/control, but most were < 10%, except those associated with expiration. CONCLUSIONS: Major differences exist for each ventilator as rise time or inspiration termination criteria are varied and among ventilators at similar settings. Inspiration termination criteria adjustment markedly affects transition to exhalation in the Puritan Bennett 840.

Calibration↗
PubMed1998

Mathematical models for predicting straining G-level tolerances in reclined subjects.

Mathematical models that predict straining G-level tolerances of subjects reclined > 55 degrees are described. Straining G-level tolerances are defined as those G-levels of exposures that require the use of the anti-G straining maneuver (AGSM). A subject reclined > 55 degrees has a reduced inspiratory volume that limits the maximum intrathoracic pressure that can be developed that is the basis for the AGSM. Therefore the inability to perform a maximum AGSM reduces the maximum G-level that can be tolerated. G-level tolerances of subjects at seat-back angles between 75 degrees and 55 degrees are modeled. The use of positive pressure breathing (PBG) to increase G-level tolerance is considered. Maximum G-level tolerances are dependent upon anti-G suit pressures (psi) used and are predicted as follows: 55 degrees = 11.7 and 12.7 G with 7 and 10 psi; 65 dergrees = 12.1 and 12.8 G with 6 and 9 psi; and 75 degrees = 13.4 and 14.2 G with 5 and 8 psi anti-G suit pressure.

Acceleration↗
PubMed2000

Pulmonary function changes following surgical correction for pectus excavatum.

OBJECTIVE: To assess whether and to what extent pulmonary function returns to normal after surgical correction for pectus excavatum. METHODS: Twenty-seven patients who could be examined in person at the outpatient department of our hospital were included in this study. Of these patients, 24 were boys and 3 were girls, with age ranging from 3 to 16 years (mean: 8.67 years). The mean age at surgery was 4 years and mean years at follow-up was 6.8. Pulmonary function measurements included inspiratory vital capacity (IVC), total lung capacity (TLC), residual volume (RV), functional residual capacity (FRC), RV/TLC ratio, maximal voluntary ventilation (MVV), forced ventilatory capacity (FVC), forced expiratory volume in one second (FEV1), maximal mid-expiratory flow (MMEF), maximal expiratory flow at 75% vital capacity (V75), maximal expiratory flow at 50% vital capacity (V50), maximal expiratory flow at 25% vital capacity (V25) and breathing reserve ratio (BR). RESULTS: TLC, FRC, MVV, MMEF, V75 and V50 were not different from normal values. IVC, FVC, FEV1 and V25 were significantly decreased compared with normal values. RV and RV/TLC were high in 87.5% cases. CONCLUSIONS: Preoperative symptoms improved substantially after operation. Little airway obstruction was observed postoperatively, suggesting that patients with pectus excavatum should have surgery as early in life as possible, preferably by age 3.

Adolescent↗
PubMed2002

[Respiratory mechanics in professional flautists].

Oesophageal, gastric, mouth, transdiaphragmatic, transpulmonary pressures, diaphragmatic EMG, sound and chest wall excursion were measured directly in 3 professional flautists whilst playing their instruments to determine: - what respiratory muscles and percent vital capacity were being used; - how mouth pressure, embouchure resistance, embouchure aperture, airflow and velocity affect sound loudness and frequency. Lung volume was estimated from transpulmonary pressure during playing and the static deflation pressure-volume curve was measured separately; flow was calculated from delta volume/delta time; embouchure resistance was calculated from mouth pressure/flow; velocity was calculated using Bernouilli's equation and mouth pressure. Staccati and sustained tones at different frequency and intensity were performed. Sound loudness was mainly related to airflow whilst sound frequency was determined by velocity. Flow and velocity were independently controlled by mouth pressure and embouchure aperture. Mean mouth pressures varied little from individual to an other (6-11 cm H(2)O) but the flautists used between 72-83% of their vital capacity suggesting inspiratory muscle activity while playing. However, rib cage and abdominal motion were different for each subject. Although different flautists use different strategies to control mouth pressure, their individual mastery of the instrument permits control of airflow and velocity to produce the desired intensity and frequency of sound.

Adult↗
PubMed2002

[Indirect evaluation of respiratory muscle strength with the help of markers of maximal inspiratory and expiratory pressure in the mouth of healthy individuals].

The aim of the study was the evaluation of respiratory muscle strength by measurement of maximal inspiratory (PImax) and expiratory (PEmax) pressures values. Results for 166 clinically normal subjects (79 female and 87 male) were obtained. The results were as follow: in woman PImax ranged 38-104 cm H2O, average 60 cm H2O, PEmax ranged 46-140 cm H2O average 87.5 cm H2O, in men PImax was 40-120 cm H2O, average 73.2 cm H2O, PEmax ranged 46-140 cm H2O, average 115.9 cm H2O. PImax was negatively correlated with age in both groups. There was no correlation between age and PImax or PEmax in both groups (p > 0.05). There was no correlation between PImax and PEmax and height in women group and men group treated apart. The correlation was found between PImax as well as PEmax and height for whole group (p = 0.00019). There were observed positive correlation between PImax, PEmax and weight in both (male and female) groups. The comparison of results of present study with those obtained in former studies reveals important differences of norms for different populations. The normal values of maximal inspiratory and expiratory pressures in the mouth (PImax, PEmax) should be qualified individually for studied population. The normal values recommended by producers of medical equipment might be inadequate for studied population.

Adolescent↗
PubMed2002

Battery duration of portable ventilators: effects of control variable, positive end-expiratory pressure, and inspired oxygen concentration.

INTRODUCTION: Portable ventilators require battery power during transport or when alternating current is unavailable. Manufacturers report battery duration at nominal ventilator settings. METHODS: We studied the effects of control variable (pressure control vs volume control), positive end-expiratory pressure (PEEP), and fraction of inspired oxygen (F(IO)(2)) on the battery duration of 8 portable ventilators: Achieva, HT50, iVent201, LTV1000, TBird Advanced Ventilator System (AVS), Avian, Uni-Vent 750, and Uni-Vent 754. Each ventilator was set to ventilate a test lung at a rate of 10 breaths/min, tidal volume of 750 mL, and inspiratory time of 1.5 s, with volume-controlled ventilation and then pressure-controlled ventilation (PCV), if available. F(IO)(2) was set at 0.21 and then 1.0. PEEP was set at 0, 10, and then 20 cm H(2)O. Test lung compliance and resistance were set at 20 mL/cm H(2)O and 5 cm H(2)O/L/s, respectively. Five trials were performed with each portable ventilator, with each combination of settings. Time to low-battery alarm, battery-empty alarm, and failure to ventilate the test lung were recorded. Portable ventilator performance during the trials was determined by continuous recording of tidal volume. RESULTS: The battery duration of pneumatically driven portable ventilators is longer than that of electrically driven portable ventilators. The battery duration of pneumatically driven portable ventilators is minimally affected by ventilator settings. The battery duration of electrically driven portable ventilators is shortened by use of PCV, increasing PEEP, and increasing F(IO)(2). Compared to zero PEEP, PEEP of 20 cm H(2)O reduced battery duration with HT50 (40%), LTV1000 (37%), TBird AVS (34%), and Achieva (15%). Compared to volume-controlled ventilation, PCV reduced battery duration with the LTV1000 (48%) and TBird AVS (18%). Compared to F(IO)(2) of 1.0, F(IO)(2) of 0.21 reduced battery duration with the Uni-Vent 754 (37%). Compared to F(IO)(2) of 0.21, F(IO)(2) of 1.0 reduced battery duration with the LTV1000 (17%) and TBird AVS (15%). The iVent201 was unable to deliver the set tidal volume with PCV and 20 cm H(2)O PEEP. Low-battery alarms functioned properly on all the ventilators. CONCLUSIONS: Battery duration differs greatly among the portable ventilators tested. Clinicians must be aware that portable ventilator battery duration is affected by control settings, lung impedance characteristics, and portable ventilator characteristics. Battery duration may be shorter than that reported in the operator's manual for each portable ventilator tested.

Electric Power Supplies↗
PubMed2002

[Spontaneous changes of nasal patency, the nasal cycle, classification, frequency, and clinical significance].

The nasal cycle is classically defined as rhythmic, alternating side to side fluctuation in nasal airflow. It is known to be regulated by autonomic nervous system probably from the centres located in brainstem. Its classical form requires identical periods and equal amplitude of patency changes, with the total airflow remaining unchanged. This pattern was previously shown to occur in 75% healthy adults. In more recent studies is has been shown that spontaneous changes in nasal patency are in most cases of more irregular pattern. This article describes methods of detection, classification, current views on the role of the cycle.

Adult↗