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PubMed1994

Respiratory monitoring in an intermediate intensive unit.

The major goal of monitoring is continuous recording of indices that enhance our understanding of the underlying pathophysiology, in order to improve diagnosis and guide management, and identify trends that assist in assessing the therapeutic response and predicting prognosis. Nowadays, technology has made it possible to automatically sense and display a wide variety of physiological indices. An ideal monitoring system should be pertinent to patient management, propose interpretable data, show high technical accuracy, high sensitivity, good reproducibility, be practical to use. The international literature, our personal experience, and cost considerations have proposed the following monitoring standards as the best for a noninvasive respiratory intermediate intensive care unit (RIICU): 1) mandatory indices: respiratory rate, oxygen saturation, haemogas-analysis, tidal volume, minute ventilation, maximum voluntary ventilation, forced expiratory volume in one second, forced vital capacity, vital capacity, maximal inspiratory pressure, heart rate and blood pressure; 2) second choice indices: capnometry, respiratory inductive plethysmography, transcutaneous monitoring of gases, haemodynamic monitoring, mechanics data by means of an oesophageal balloon, and central drive. Pulmonary monitoring devices shorten the time for patients who remain on mechanical ventilators; a reduction both in the risk of associated complications and the costs involved is a natural consequence. Continuous monitoring of significant physiological indices has the potential for predicting a critical event, and providing an opportunity for the institution of lifesaving measures.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical Care↗
PubMed1993

[Possible existence of spinal inspiratory activity in the in vitro brain stem-spinal cord preparation from newborn rats].

Summing up with classical shortlasting inspirations, periodic longlasting inspirations (approximately 10 s) may be recorded with the normal inspirations through plethysmographic method in the intact newborn rat under deep diethyl ether anaesthesia. When they are present in vivo, the fast brainstem-spinal cord isolation allows to record in vitro periodic longlasting motor bursts (10-25 s) on C2-C8 ventral roots adding to shortlasting respiratory bursts (1-3 s) on C1-T13 ventral roots. Both kinds of rhythmic activities display a synchronous bilateral pattern. The longlasting bursts are maintained after a C2 spinal transection, especially if they have been induced by phenylephrine hydrochloride superfusion (0.4-0.5 mM).

Animals↗
PubMed1993

[Evaluation of a portable device for measuring maximal inspiratory pressure (Pimax)].

Pimax measurement is useful for quantifying the fatigue of the respiratory muscles (the "respiratory pump" of the mechanics of respiration), for controlling the therapeutic effect of artificial respiration performed at home, and assessment of the possibility of relieving a patient from artificial respiration. So far, such measurement had required complicated set-ups. A portable alternative is now available for Pimax measurement (MPM, distributed by Medanz, Starnberg, Germany). In a prospective study we compared the Pimax values measured via the mouth pressure measuring instrument under test, with the standard laboratory method. Statistical comparison of the measured data yielded a high degree of correlation (r = 0.97) with slight scatter of the individual data around the identity line. The portable instrument tested in this manner thus represents a mobile method yielding reliable Pimax values both on an inpatient and an outpatient basis.

Adult↗
PubMed1993

[The relative contribution of the muscles of the chest cavity and diaphragm to the work of breathing under inspiratory resistive loading].

The inspiratory resistive load decreases the relative contribution of the diaphragm into formation of the respiratory volume, as has been show in anesthetised cats. The phenomenon can be due to both a sharp increase in the external intercostal muscles activity and to a fatigue of the diaphragmatic muscle in the inspiratory load. The contraphasic changes of these muscles' activity seem to be an adaptive response aiding to a more efficient overcoming of the resistance against breathing.

Airway Resistance↗
PubMed1993

The effect of prone immersion on bronchial responsiveness in children with asthma.

We studied the effects of prone immersion on pulmonary function in children with asthma. Twelve children with asthma were subjected to prone immersion (WET) and standing upright on land (DRY) under controlled conditions regarding temperature and relative humidity of the inhaled air, minute ventilation, respiratory frequency, tidal volume, and the concentration of carbon dioxide in the exhaled air. Eight minutes of isocapnic hyperpnea was performed in random order either in the swimming pool (prone) or on land (upright), with the temperature and relative humidity of the inhaled air kept at 20 +/- 2 degrees C and 10 +/- 2%, respectively. The average accumulated ventilation for the 8 min of hyperpnea was 3151 for the WET treatment and 3101 for the DRY (P > 0.1). Average heart rates were 101 +/- 11 and 115 +/- 17 beats.min-1 for the WET and DRY treatments, respectively (P < 0.05). The decrease in FEV1 (delta FEV1) was 26.3 +/- 16.7% after the WET treatment (compared with pretreatment FEV1), and 26.4 +/- 11.3% after the DRY treatment (P > 0.1 between WET and DRY delta FEV1), with similar trend (insignificant differences between treatments), for delta FVC, delta PEF 50%, and delta PEF 25-75%. It is concluded that airway hyperactivity is not alleviated by whole body prone immersion.

Adolescent↗
PubMed1993

[Fatigue resistance of inspiratory muscles in patients with severe mitral valve stenosis].

The strength and endurance of the inspiratory muscles was assessed in 14 patients with severe mitral valve stenosis uncomplicated by other diseases. Strength was evaluated measuring the maximal static inspiratory pressure (MIP). Endurance was measured using a two minute weight incremental test, to obtain the maximal sustainable pressure (SIP), which is the highest pressure that a subject can generate to mobilize air with incremental weight during inspiration. MIP was similar to that of 8 normal subjects (110 +/- 21 and 128 +/- 27 cm H2O respectively p = NS). SIP, maximal sustainable weight and SIP as percentage of MIP were 47 +/- 10 cm H2O, 261 +/- 81 g and 43 +/- 6% respectively, all lower than in normal subjects (89 +/- 25 cm H2O, 525 +/- 167 g and 71 +/- 15% respectively) We conclude that patients with severe mitral valve stenosis have decreased inspiratory muscle endurance compared to normal subjects and this feature may be related to their decreased exercise tolerance.

Adult↗
PubMed1993

[Clinical application of the forced inspiratory volume-time curve. A preliminary study].

The forced inspiratory volume-time curve in 25 health subjects with normal ventilation function and 25 patients with COPD were determined, and MMIF, FIV were calculated from the curves. The PImax was measured in the same 50 subjects by modified Blac method sequentially. A close relationship between MMIF, FIV and PImax was found. This result indicated that MMIF and FIV could be indeed for evaluation of strength of respiratory, muscles. Additional observations of MMIF, FIV and PImax in 50 patients with COPD before and after inotropic drugs, aminophylline and CNB, further proved the validity of MMIF and FIV.

Aged↗
PubMedDate not supplied

Inspiratory muscle training in patients with chronic obstructive pulmonary disease.

The effects of 6 months of muscle training with an inspiratory pressure load equal to 30% of the maximal inspiratory pressure (PImax) was compared with sham training with a light inspiratory pressure load. In this double-blind randomly assigned study, 67 patients with chronic obstructive pulmonary disease were followed for 6 months. Both groups demonstrated improvements in performance of PImax, respiratory muscle endurance time for breathing against an inspiratory pressure load equal to 66% of PImax, 12-minute distance walk, and dyspnea. The treatment group did not demonstrate significant effects beyond those observed in the control group. Improvements in performance were related to improved coordination of the inspiratory muscles and desensitization to dyspnea.

Activities of Daily Living↗
PubMed1977

[Ventilation distribution disorders. Evaluation based on nitrogen elimination curves of the lung and on an inspiratory gas-distribution index derived from it].

An uneven distribution of the inspiratory gas volume to the alveolar volume leads to disturbances of the ventilation/perfusion ratio VA/Q with resulting arterial hypoxemia. These ventilatory disturbances can be verified by nitrogen-washout-curves and an inspiratory gas distribution index derived from those curves. Preoperative diagnostic and the control of respiratory diseases during intensive therapy are possible without technical difficulties.

Humans↗
PubMed1993

Variability of forced oscillation (Siemens Siregnost FD 5) measurements of total respiratory resistance in patients and healthy subjects.

The reproducibility of total respiratory resistance (Rrs) measured with a simplified forced oscillatory method (Siemens Siregnost FD 5) was measured and compared with that of slow inspiratory vital capacity (IVC) and forced expiratory volume in one second (FEV1). The former technique has the advantage that assessment of bronchial obstruction can be made without a forced maneuver, which may be difficult in patients with chronic obstructive pulmonary disease (COPD). We used the criteria proposed by the American Thoracic Society for the diagnosis of COPD. Pulmonary function tests (IVC, FEV1 and Rrs) were measured in seven healthy subjects and in two groups of patients with COPD. First one technician performed six measurements of IVC, FEV1 and Rrs in all subjects during a period of 90 minutes on the same day. Second to evaluate intraindividual variability the measurements were performed on ten subsequent days. The median interval (range) between the first and last measurements in days was 38 (20-186). The mean +/- SD coefficient of variation (CV) Rrs in patients was 15.7% +/- 5.0% and in normals, 10.8% +/- 3.2%. There was less variation in the FEV1 value of 11.0% +/- 6.2% and normals, 2.2% +/- 1.0%; and IVC, 6.9% +/- 5.0% and normals, 2.4% +/- 0.7%. There is no correlation between age and CV. It is concluded from the study that oscillatory Rrs has a larger coefficient of variation within one patient than FEV1 or IVC. If Rrs is used for longitudinal follow-up in COPD patients, we suggest that variations less than 26% (mean +/- 2 SD) can be considered the result of "spontaneous" variation in lung function.

Adult↗
PubMed1993

Airways hyperresponsiveness, bronchodilator response, allergy and smoking predict improvement in FEV1 during long-term inhaled corticosteroid treatment. Dutch CNSLD Study Group.

Although most patients with obstructive airways disease show some amelioration with long-term inhaled corticosteroid therapy, the extent of improvement may vary considerably between patients. Patients with mild to moderately severe obstructive airways disease (asthma and COPD) were selected if provocative concentration producing a 20% fall in forced expiratory volume in one second (PC20) < or = 8 mg.ml-1, and forced expiratory volume in one second (FEV1) < 95% confidence intervals (CI) of predicted normal. The independent influences of baseline PC20FEV1, inspiratory vital capacity (IVC), bronchodilator response, smoking habits, and allergy both on the "immediate" (within 3 months) response in FEV1 and the change in long-term (from 3 months onwards) slope of FEV1 with inhaled corticosteroids were analysed. Patients had a larger "immediate" improvement in their FEV1 with inhaled corticosteroids with each doubling doses lower PC20, with each ten-fold higher immunoglobulin E (IgE), and if they did not smoke. Total IgE proved a better independent predictor of "immediate" response than specific IgE for house dust mite, skin tests, or blood eosinophils. A more favourable long-term slope of FEV1 was predicted by a larger baseline bronchodilator response, but not by smoking. In conclusion, PC20, total IgE, and smoking habits are independent predictors of immediate treatment response to inhaled corticosteroids. Bronchodilator response is the single independent predictor of changes in long-term slope of FEV1 with corticosteroid treatment.

Administration, Inhalation↗
PubMed1993

Exercise ventilatory response to upright and aero-posture cycling.

The aero-cycling posture has become increasingly popular among cyclists. Because of the potential for altered lung mechanics in the aero-cycling posture, the ventilatory and gas exchange profiles of 10 moderately trained males (31.1 +/- 6.3 yr, mean +/- SD) exercising on a cycle ergometer in the upright posture (UC) and aero-cycling (AC) posture were studied. Exercise consisted of 3-min work stages with 50-W incremental changes until volitional exhaustion. Ventilatory and gas exchange responses to exercise were averaged each minute. Maximal oxygen consumption (54.3 +/- 6.3 vs 53.4 +/- 6.9 ml.kg-1.min-1) in the UC and AC were not significantly different. Maximal values for ventilation (132.5 +/- 32.3 vs 128.0 +/- 28.7 l.min-1), tidal volume (2.7 +/- 0.5 vs 2.6 +/- 0.3 1.br-1), breathing frequency (50.0 +/- 8.0 vs 47.0 +/- 5.0 br.min-1), and submaximal ventilatory and heart rate responses in the UC were not significantly different compared with the AC. No significant difference existed between postures for mean inspiratory flow and inspiratory duty cycle at comparable submaximal power outputs. These results indicate that at absolute power outputs, ventilatory responses, as determined by respiratory pattern and timing, and metabolic cost, were similar in the UC and AC. Thus, the AC does not impair physiologic responses to high intensity exercise.

Adult↗
PubMed1996

Evaluation of two different oxygen inspiratory fractions on the hemodynamic effects of N omega-nitro-L-arginine methyl ester in anesthetized dogs.

The effect of two different oxygen inspiratory fractions (FiO2 = 21% and 100%) on the hemodynamic responses induced by N omega-nitro-L-arginine methyl ester (L-NAME) was investigated in anesthetized dogs. L-NAME (0.01-10.0 mg/kg), but not D-NAME, induced dose-dependent changes in the hemodynamic parameters of the animals. At the highest dose, L-NAME increased mean arterial blood pressure in both room air (from 86.2 +/- 3.2 to 125.1 +/- 7.8 mmHg) and pure oxygen (from 100.0 +/- 7.5 to 139.0 +/- 3.2 mmHg) ventilated animals. L-NAME also increased systemic and pulmonary vascular resistances. These effects were accompanied by a decrease in cardiac output and bradycardia (37% and 31% decreases for pure oxygen and room air, respectively). However, there were no significant differences in the responses to L-NAME between the dogs ventilated with FiO2 = 21% and those ventilated with FiO2 = 100%. L-NAME did not modify blood gas analyses, despite the expected difference in pO2 levels between the two experimental groups of animals (3 times higher in the animals ventilated with pure oxygen). These results indicate that nitric oxide release accounts for the maintenance of hemodynamic function in the anesthetized dog, and that L-NAME-induced effects are not affected by hyperoxemia.

Animals↗
PubMed1996

[Postoperative changes of maximum inspiratory and expiratory pressures in 3 pneumonia cases occurring after surgery for empyema].

We examined preoperative and postoperative maximum inspiratory (MIP) and expiratory (MEP) pressures in 3 cases who died of postoperative pneumonia occurring more than one month after open drainage thoracotomy for empyema. All cases showed reduction of MIP and MEP to less than 20 cmH2O one month after surgery, then suffered of pneumonia. On the other hand, the other 3 cases with empyema who underwent open drainage thoracotomy and recovered without complication showed recovery of MIP and MEP one month after surgery. In conclusion, for the cases that underwent thoracic surgery, postoperative MIP and MEP are the index of respiratory condition such as deep diaphragmatic breathing and ability of efficient coughing, and can be an early prediction of late onset pneumonia after thoracic surgery.

Aged↗
PubMed1996

[Evaluation of the inspiratory muscle strength using the nasal pressure of the sniff].

The measurement of oesophageal pressure during maximal sniffs (Poes sniff) is useful to assess inspiratory muscle strength. The aim of this study was to develop a noninvasive test of inspiratory muscle strength based on the sniff manoeuvre. The sniff nasal inspiratory pressure (SNIP) was measured through a plug occluding one nostril during sniffs performed through the contralateral nostril. In 10 normal subjects and in 12 patients with neuromuscular or skeletal disorders, the SNIP reliably reflected the Poes sniff. Nasal mucosa congestion was induced in four normal subjects by nebulization of increasing doses of histamine. The SNIP accurately reflected Poes sniff when nasal congestion was moderate, but failed to do so when congestion was severe. Reference values of SNIP were established in a group of 160 healthy subjects aged 20-80 years. For both men and women, SNIP was negatively correlated with age, and was similar in the sitting and in the supine positions. SNIP was higher than maximal inspiratory pressure (P1 max) in most subjects, but the wide limits of agreement showed that these two methods are not interchangeable but complementary. The SNIP represents a useful noninvasive test of inspiratory muscle strength.

Adult↗
PubMed1997

Effect of inhaled beclomethasone dipropionate on isocapnic hyperventilation with cold air in asthmatics, measured with forced oscillation technique.

Isocapnic hyperventilation with cold air (IHCA) is a reliable technique for assessing indirect bronchial hyperresponsiveness in patients with asthma. Impedance measurement of the respiratory system by the forced pseudorandom noise oscillation technique is a sensitive technique to assess changes in bronchial tone after IHCA. The aim of this study was to evaluate the effect of 6 weeks of treatment with beclomethasone dipropionate, 1,000 microg x day-1, on IHCA in asthmatic patients, measured with both forced oscillation technique and flow-volume recordings. Forty patients with mild asthma were included in this double-blind, placebo-controlled parallel-group study. Stratification on the basis of sex was performed to overcome differences in airway diameter. At entry and every 2 weeks during the treatment period, IHCA was performed and patient diaries were evaluated. Characteristic changes in forced oscillation parameters after IHCA were observed in all patients. After 6 weeks of treatment, BDP-treated patients showed statistically significant differences in impedance measurements after IHCA, manifested by significant attenuation of resistance at 8 Hz (p<0.01), slope of the frequency-resistance curve (p<0.01), reactance at 8 Hz (p=0.01), and resonant frequency (f0) (p<0.02). Flow-volume recordings showed only a statistically significant change in the decrease of inspiratory vital capacity (IVC) (p=0.01). Furthermore, a significant correlation was observed between serum immunoglobulin E (IgE) levels and the effect of BDP on IHCA, measured with forced oscillation technique. In this study, beclomethasone dipropionate, 1,000 microg x day(-1) for 6 weeks, decreased indirect bronchial hyperresponsiveness as assessed by cold air bronchoprovocation in asthmatic patients. The forced oscillation technique proved a more sensitive method of detecting changes in bronchial tone than flow-volume recordings.

Adult↗