Changes in Depressed Mood Associated with 10 Weeks of Moderate Cardiovascular Exercise in Formerly Sedentary Adults

Two groups of adults classified with depressed mood (10% highest scores on the Profile of Mood States-Short Form Depression scale) were contrasted on changes in POMS Depression scores over 10 weeks. The exercise group ( n = 26) was given a moderate cardiovascular exercise program of 3x/week for 20 to 30 min. per session. The control group ( n = 24) did not participate in exercise. Significant reductions in POMS Depression scores over 10 weeks were noted for the exercise group in between-group ( d = –.88) and within-group ( d = −1.32) analyses. Significantly more participants in the exercise group scored in the normal range at Week 10 (62%) than in the control group (29%). Neither changes in cardiorespiratory function (VO2 max) nor initial POMS Depression scores were significantly correlated with changes in POMS Depression scores after 10 weeks. Methodological improvements, limitations, and practical application of findings after replication were discussed.

APPLICATION OF LAPAROSCOPIC LIFTING SYSTEMS IN PATIENTS WITH HIGH CARDIORESPIRATORY RISK

Intra-abdominal hypertension during laparoscopic operations increased the risk of complications from cardiovascular and respiratory systems. An application of laparolifting systems allowed doctors to avoid changes of pneumoperitoneum, although it was associated with technical difficulties in operation performance. The authors used a test in order to determine cardiorespiratory reserve in preoperative period. The reserve was characterized by decrease of stroke volume of the heart against the background of intra-abdominal hypertension. There was noted a reliable increase of complication rate in these patients in case of application of standard laparoscopic operation compared with operation using lifting systems.

Correlated variability in the breathing pattern and end-expiratory lung volumes in conscious humans

In order to characterize the variability and correlation properties of spontaneous breathing in humans, the breathing pattern of 16 seated healthy subjects was studied during 40 min of quiet breathing using opto-electronic plethysmography, a contactless technology that measures total and compartmental chest wall volumes without interfering with the subjects breathing. From these signals, tidal volume (V_T), respiratory time (T_TOT) and the other breathing pattern parameters were computed breath-by-breath together with the end-expiratory total and compartmental (pulmonary rib cage and abdomen) chest wall volume changes. The correlation properties of these variables were quantified by detrended fluctuation analysis, computing the scaling exponentα. V_T, T_TOT and the other breathing pattern variables showed α values between 0.60 (for minute ventilation) to 0.71 (for respiratory rate), all significantly lower than the ones obtained for end-expiratory volumes, that ranged between 1.05 (for rib cage) and 1.13 (for abdomen) with no significant differences between compartments. The much stronger long-range correlations of the end expiratory volumes were interpreted by a neuromechanical network model consisting of five neuron groups in the brain respiratory center coupled with the mechanical properties of the respiratory system modeled as a simple Kelvin body. The model-based α for V_T is 0.57, similar to the experimental data. While the α for T_TOT was slightly lower than the experimental values, the model correctly predicted α for end-expiratory lung volumes (1.045). In conclusion, we propose that the correlations in the timing and amplitude of the physiological variables originate from the brain with the exception of end-expiratory lung volume, which shows the strongest correlations largely due to the contribution of the viscoelastic properties of the tissues. This cycle-by-cycle variability may have a significant impact on the functioning of adherent cells in the respiratory system.

Relationship between %HRmax, %HR Reserve, %V˙O2max, and %V˙O2 Reserve in Elite Cyclists

PURPOSE

To evaluate the relations between %HRmax, %HRR, %VO2max, and %VO2R in elite cyclists and to check whether the intensity scale recommended by ACSM in its 1998 position stand is also applicable to this specific population.

METHODS

Twenty-six male elite road cyclists (25.1 +/- 0.7 yr, 71.0 +/- 1.2 kg, 70.9 +/- 1.2 mL x kg(-1) x min(-1), 433.9 +/- 9.8 W) performed an incremental maximal exercise test (50 W x 3 min(-1)). Individual linear regressions based on HR and VO2 values measured at rest, end of each stage, and maximum, were used to calculate slopes and intercepts, and to predict %HRmax, %HRR, %VO2max, or %VO2R for a given exercise intensity.

RESULTS

Below 85% VO2max or VO2R, predicted %HRmax values were significantly higher (P < 0.001) than the ACSM intensity scale (58, 65, 73, and 87% vs 55, 62, 70, and 85% HRmax at 40, 50, 60, and 80% VO2max, and 48, 61, 74% vs 35, 55, and 70% HRmax at 20, 40, and 60% VO2R). The %HRR versus %VO2max regression mean slope (1.069 +/- 0.01) and intercept (-5.747 +/- 0.80) were significantly different (P < 0.0001) from 1 and 0, respectively. Conversely, the %HRR versus %VO2R regression was indistinguishable from the line of identity (mean slope = 1.003 +/- 0.01; mean intercept = 0.756 +/- 0.7). Predicted %VO2R values were equivalent to %HRR in the 35-95%HRR range. %VO2max was equivalent to %HRR at and above 75%HRR, and it was significantly higher at (P < 0.05) and below 65%HRR (P < 0.001).

CONCLUSION

The intensity scale recommended by ACSM underestimates exercise intensity in elite cyclists. Prediction of %HRR by %VO2R is better than by %VO2max. Thus, elite cyclists should use %HRR in relation to %VO2R rather than in relation to %VO2max.

The relationship between heart rate reserve and oxygen uptake reserve in children and adolescents

The purpose of the present study was to examine the relationship between oxygen uptake (VO2) and heart rate (HR) responses during rest and exercise in Chinese children and youth and to evaluate the relationships between maximal heart rate (%HRmax), heart rate reserve (%HRR), peak oxygen uptake (% VO2peak), and oxygen uptake reserve (% VO2R) in Chinese children and youth. Forty-nine Chinese children and youth were studied at rest and during a graded maximal exercise test on treadmill. Resting, submaximal and peak HR and VO2 were collected. Regression analyses were conducted to investigate the associations between the various forms of HR and VO2 measures. The equivalency between %HRR and % VO2R for adults was examined for children using data obtained in this study. Results indicated that all regression lines between HR measures and VO2 measures were significantly different from the line of identity (p < .05), except the regression line for %HRR versus %VO2 peak in boys. The equivalency between % VO2R and % HRR for adults was not demonstrated in children and adolescents in this study. In contrast, %HRR was more closely equivalent to % VO2 peak. Because a strong linear relationship was found between HR and VO2, HR measures, in terms of either %HRmax or %HRR, would still be a practical variable for prescribing appropriate exercise intensity for children and adolescents. Unlike results found for adults, a given % HRR in children and youth was not equivalent to its corresponding % VO2R.

Lung volume dependence of pharyngeal cross-sectional area by acoustic pharyngometry

Pharyngeal size and the dynamic behavior of the pharynx may be important factors in the modulation of pharyngeal airflow. There are two measures of pharyngeal function: changes in pharyngeal area with lung volume and changes in pharyngeal area in response to externally applied positive pressure. Both measurements have been used for the assessment of pharyngeal function, and both reflect pharyngeal "floppiness." The aim of the present study was to examine the relationship between pharyngeal cross-sectional area, using acoustic reflection technique, and different lung volumes (tidal volume, inspiratory reserve volume, and expiratory reserve volume), to determine whether there are differences in mechanical properties of the pharynx of normal volunteers in response to changes in intrapharyngeal pressure. The acoustic technique was used to assess the pharyngeal cross-sectional area of 40 healthy volunteers (29 men and 11 women) at tidal volume, inspiratory reserve volume, and expiratory reserve volume. In men, the mean pharyngeal area at tidal volume was 3.191 cm2, the mean pharyngeal area at inspiratory reserve volume was 2.976 cm2, and the mean pharyngeal area at expiratory reserve volume was 2.975 cm2. In women, the corresponding pharyngeal area measurements were 2.832, 2.484, and 2.492 cm2. Statistical analysis of results showed that men have a larger pharyngeal cross-sectional area and the pharyngeal airways of men and women act in a similar manner in response to changes in intrapharyngeal pressure, with men having a greater change. Examination of the pharyngeal compliance by acoustic pharyngometry adds to the potential of this technique as a tool for the evaluation of the pharyngeal airway in terms of area and dynamic behavior assessment. This may be of relevance in promotion of the development of upper airway assessment in patients with obstructive sleep apnea.

Inspiratory flow reserve in boys with Duchenne muscular dystrophy

Patients with advanced muscular dystrophy frequently develop ventilatory failure. Currently respiratory impairment usually is assessed by measuring vital capacity and the mouth pressure generated during a maximal inspiratory maneuver (PI,max), neither of which directly measures ventilatory capacity. We assessed inspiratory flow reserve in 26 boys [mean (SD) age 12.8 (3.8) years] with Duchenne muscular dystrophy (DMD) without ventilatory failure and in 28 normal boys [mean (SD) age 12.6 (1.9) years] by analyzing the ratio between the largest inspiratory flow during tidal breathing (V'I,max(t)) and during a forced vital capacity maneuver (V'I,max(FVC), (V'I,max(t)/V'I,maxFVC). We have compared this ratio with the forced vital capacity FVC and PI,max measured at functional residual capacity. Mean PI,max was -90(30)cmH2O, average 112% (range 57-179%) of predicted values in control boys and -31(11)cmH2O, average 40% predicted values in DMD boys (control vs DMD, P < 0.001). FVC was reduced in DMD boys [59(20)% predicted values vs 86(10)% predicted values in controls, P < 0.01]. Absolute V'I,max(FVC) was strongly related to FVC in both control and DMD boys; V'I,max(FVC) (expressed as FVC. s(-1)) was not related to PI,max in either group. The mean V'I,max(t)/V'I,max(FVC); ratio was higher in DMD 0.22 (0.08) than in controls 0.12 (0.03) (P < 0.001) indicating a reduction in inspiratory flow reserve in DMD. Inspiratory flow reserve was within the normal range in 8 of 19 DMD patients with PI,max less than 50% of predicted values. We conclude that measurement of inspiratory flow reserve (V'I,max(t)/V'I,maxFVC ratio) provides a simple and direct assessment of dynamic inspiratory muscle function which is not replicated by static measurement of PI,max or vital capacity and might be useful in assessment of respiratory impairment in boys with Duchenne muscular dystrophy. Follow-up studies are required to establish whether measures of inspiratory flow reserve are of clinical value in predicting subsequent ventilatory failure.

Preoperative evaluation of cardiopulmonary reserve with the use of expired gas analysis during exercise testing in patients with squamous cell carcinoma of the thoracic esophagus

OBJECTIVE

We evaluated the usefulness of analyzing expired gas during exercise testing for the prediction of postoperative cardiopulmonary complications in patients with esophageal carcinoma.

BACKGROUND DATA

Radical esophagectomy with 3-field lymphadenectomy is performed in patients with thoracic esophageal carcinoma but has a high risk of postoperative complications. To reduce the surgical risk, we performed preoperative risk analysis using 8 factors. Although hospital mortality was decreased when this risk analysis was used, severe cardiopulmonary complications still occurred.

METHODS

The study group consisted of 91 patients who had undergone curative esophagectomy with 3-field lymphadenectomy. The maximum oxygen uptake, anaerobic threshold, vital capacity, percent vital capacity, forced expiratory volume in 1 second, percent forced expiratory volume, V.(25)/HT, forced expired flow at 75% of forced vital capacity to height ratio (FEF(75%)/HT), forced expired flow at 50% to 75% of forced vital capacity ratio (FEF(50%)/FEF(75%)), percent diffusion capacity for carbon monoxide, and arterial oxygen tension were measured. Patients were divided into 2 groups on the basis of the presence or absence of postoperative cardiopulmonary complications.

RESULTS

Only the maximum oxygen uptake was significantly different between the 2 groups. All patients were grouped according to the value of the maximum oxygen uptake, and the occurrence of postoperative cardiopulmonary complications was calculated for each group. A cardiopulmonary complication rate of 86% was found for patients with a maximum oxygen uptake of less than 699 mL. min(-1). m(-2); for those with a value of 700 to 799 mL. min(-1). m(-2), the complication rate was 44%.

CONCLUSIONS

The maximum oxygen uptake obtained by expired gas analysis during exercise testing correlates with the postoperative cardiopulmonary complication rate. On the basis of these results, esophagectomy with 3-field lymphadenectomy can be safely performed in patients with a maximum oxygen uptake of at least 800 mL. min(-1). m(-2).

Reproducibility of the alternating breath test of fractional inspired O2 in infants

We conducted a reproducibility study of the alternating breath test (ABT) for assessing peripheral chemoreceptor function in infants. The ABT delivers a rapid hypoxic stimulus to the peripheral chemoreceptors with breath-by-breath alternations of the inspired O2 fraction. The reproducibility of the ABT performed on a single occasion has not been extensively studied in infants. Eight unsedated infants (postnatal age, 22+/-19 d; weight, 3.2+/-0.4 kg) were studied in standardized conditions: morning naps, supine position, room temperature 22-24 degrees C, quiet sleep, and face mask attached to a pneumotachograph connected to a two-way electric valve. Respiratory gases were analyzed by mass spectrometer. Two ABTs were performed. Each included a 2-min control run (CR) alternating between air and air, and a 2-min test run (TR) alternating between air and 0.15 O2. After data preprocessing, on average 13+/-11% of the data were rejected because of sighs, apneas, and cycles with the fraction of inspired oxygen above 0.17. Using the remaining validated breaths, the response to ABT was calculated for the CR, for all breaths in the TR (TR(T)), and for the first 50 breaths of the TR (TR50). During the ABTs oxygen saturation did not fall below 96%, and heart rate was not affected. Inspired and end-tidal CO2 fractions remained unchanged during the ABTs. FetO2 oscillated in TRs at a lower values than in CRs and differed significantly between breaths of air and hypoxic breaths of TRs. All infants responded to ABT with percentage alternation coefficients of TRs significantly greater than those of CRs for all respiratory variables. The values of the coefficients were not significantly different between both ABT, and between TR50 and TR(T). The greatest values of the coefficients were for timing variables compared with flows and volume. We conclude that the ABT is a reproducible test of peripheral chemoreceptor function under standardized conditions.

Automated VO2max calibrator for open-circuit indirect calorimetry systems

The complete calibration of indirect calorimetry systems involves simultaneous checks of gas analyzers, volume device, and software, and this requires a machine that can mimic accurately and precisely the ventilation and expired gases of an athlete. While previous calibrators have been built successfully, none have matched the ventilatory flows produced by athletes during high intensity exercise. A calibrator able to simulate high aerobic power (VO2max calibrator) was fabricated and tested against conventional indirect calorimetry systems that use chain-compensated gasometers to measure expired volume (VE systems) and calibrated electronic gas analyzers. The calibrator was also checked against a system that measures inspired volume (VI system) with a turbine ventilometer. The pooled data from both VE and VI systems for predicted VO2 ranging from 2.9 to 7.9 L.min-1 and ventilation ranging from 89 to 246 L.min-1 how that the absolute accuracy (bias) of values measured by conventional indirect calorimetry systems compared with those predicted by the calibrator was excellent. The bias was < 35 mL.min-1 for VO2 and carbon dioxide production, < 0.50 L.min-1 for ventilator (VE BTPS), -0.02% absolute for the percentage of expired O2 and +0.02% absolute for the percentage of expired CO2. Overall, the precision of the measured VO2, VCO2, and VE BTPS was approximately 1%. This VO2max calibrator is a versatile device that can be used for routine calibration of most indirect calorimetry systems that assess the ventilation and aerobic power of athletes.

[Occlusion pressure in the first 100 ms of inspiration (P0.1) as an index of the possibility of decreasing respiratory support in acute respiratory failure]

The need in making the process of transfer of patients to spontaneous respiration using ventilation of the lungs with inspiratory pressure support (VLIPS) after prolonged mechanical ventilation of the lungs prompted the authors to analyze the prognostic value of criteria traditionally used by the physician to cease or decrease the respiratory support (vital capacity of the lungs, peak spontaneous flow, PaO2, etc.) and the P0.1 occlusion pressure in the airways at the end of the first 100 msec of inhalation. This latter value proved to be the most sensitive (88%), specific (86%), positive (95%) and negative (67%) prognostic value in predicting the results of decrease of respiratory support under conditions of VLIPS. The P0.1 value determining the result of decrease of respiratory support in patients with parenchymatous pulmonary diseases under conditions of VLIPS is 3.8 cm H2O.

Determination of gas-trapping during high frequency oscillatory ventilation

OBJECTIVE

To determine the effect of frequency and percent inspiratory time on tidal volume and gas-trapping during high-frequency oscillatory ventilation (HFOV).

SUBJECTS

Nine preterm infants with respiratory distress syndrome tested in the first 48 h of life.

METHODS

Tidal volumes and the presence of gas-trapping were measured by respiratory jacket plethysmography at frequencies of 10, 14, and 17.8 Hz and at inspiratory times of 30%, 50% and 70%, using a commercially available high frequency oscillator.74

RESULTS

Mean (SD) tidal volumes were 2.40 (1.06) ml/kg at 10 Hz, 2.52 (1.07) ml/kg at 14 Hz and fell significantly to 1.96 (0.92) at 17.8 Hz (p < 0.05). Tidal volumes at 50% inspiratory time were significantly greater than at 30% inspiratory time [2.81 (1.42) ml/kg and 2.32 (1.18) ml/kg, respectively] but fell to baseline levels at 70% inspiratory time. There was no significant gas-trapping with increases in either frequency or percent inspiratory time.

CONCLUSIONS

Gas-trapping is not a significant problem during HFOV in premature infants. Changes in tidal volume with increases in frequency and percent inspiratory time are similar to that seen in animal models.

Incentive spirometry performance. A reliable indicator of pulmonary function in the early postoperative period after lobectomy?

OBJECTIVES

The purpose of our study was to validate the incentive spirometry (IS) as a simple mean to follow pulmonary function at the bedside after lung surgery.

MATERIALS AND METHODS

We studied prospectively 19 patients (16 men, 3 women; mean +/- SE age, 60 +/- 2.8 years) undergoing lobectomy for lung cancer. All the patients had an obstructive pattern with FEV1/FVC below 75%. Lung volumes, including functional residual capacity (FRC) and residual volume (RV), measured using spirometry and the helium dilution technique, and IS were measured preoperatively and postoperatively at days 1, 2, 3, and 8, and at 2 months.

RESULTS

Our results showed that in the postoperative period after lung resection, IS performance was well correlated (R) during the first 8 postoperative days with vital capacity (VC) (R between 0.667 and 0.870) mainly due to the excellent correlation with the inspiratory reserve volume (IRV, R between 0.680 and 0.895) but was poorly correlated with expiratory reserve volume (R below 0.340), RV (R below 0.180), and FRC (R below 0.470).

CONCLUSIONS

IS can be used as a simple mean to follow lung function, especially VC and IRV, in the postoperative period in spontaneously breathing patients. IS is noninvasive and can be performed repeatedly at the bedside in the intensive care setting.

The relationship between tPTEF:tE and specific airway conductance in infancy

This study examines the association between the time taken to achieve peak tidal expiratory flow as a proportion of total expiratory time (tPTEF:tE) and specific airways conductance (SGaw) in healthy infants and those with prior physician diagnosed, associated, lower respiratory illness with wheezing (prior LRI) during the first year of life. We compared tPTEF:tE and SGaw, the latter estimated during both initial inspiration (ll) and end-expiration (EE), in 168 infants (94 males), measured on 220 occasions. Mean (range) tPTEF:tE was 0.321 (0.150-0.522) in 73 healthy infants aged less than 3 months (mean, 7.8 weeks), in whom mean (range) EE SGaw and plethysmographic thoracic gas volume at functional residual capacity (FRCpleth) were 2.47 s-1 kPa-1 (0.6-5.8) and 141 mL (87-204), respectively. Both tPTEF:tE and EE SGaw were significantly lower in older infants with prior LRI (n = 79; mean age, 50.0 weeks) compared to a similarly aged group of healthy infants (n = 68; mean age, 48.5 weeks), the mean difference [95% confidence intervals (CI)] being -0.039 (-0.013, -0.064) and -0.48 s-1 kPa-1 (-0.24, -0.72), respectively. A significant but weak association between tPTEF:tE and EE SGaw was found among infants above 3 months of age, irrespective of prior wheezing status. However, this relationship was not significant in healthy younger infants, in whom a significant but weak association with FRCpleth was found. Further work is needed to elucidate the factors influencing tidal expiratory flow patterns in infancy.

Exertional breathlessness in patients with chronic airflow limitation. The role of lung hyperinflation

There is considerable intersubject variability in the perceived intensity of breathlessness for a given level of activity among patients with chronic airflow limitation (CAL). To examine possible factors contributing to this variability we compared breathing pattern parameters, dynamic operational lung volumes, and Borg dyspnea ratings in 23 patients with severe CAL and in 10 healthy age-matched normal subjects during cycle ergometry to symptom-limitation. Patients with CAL had significantly (p < 0.01) higher levels of ventilation (% maximal voluntary ventilation) for a given work rate (slope of VE(%MVV)/WR(% pred max) = 1.51 +/- 0.18 versus 0.63 +/- 0.10; mean +/- SEM) and greater dynamic lung hyperinflation (DH) (change [delta] in end-expiratory lung volume [EELVdyn] = +0.31 +/- 0.11 L versus -0.16 +/- 0.22 L). Compared with normal subjects at a standardized VE (30 L/min), the CAL group was more breathless Borg = 4 +/- 1 versus 2 +/- 1, p < 0.01) and hyperinflated (EELVdyn = 75 +/- 3 versus 46 +/- 6% TLC, p < 0.001; end-inspiratory lung volume [EILVdyn] = 85 +/- 3 versus 67 +/- 5% TLC, p < 0.01). Within the CAL group, change in Borg ratings correlated with delta VE(%MVV) (r = 0.77, p < 0.001) and with slope of VE(%MVV)/WR(% pred max) (r = 0.48, p < 0.01). Regression analysis selected delta EILVdyn (or delta inspiratory reserve volume [delta IRVdyn]) from various dynamic ventilatory parameters as the strongest predictor of delta Borg (r = 0.63, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Intratracheal pulmonary ventilation and congenital diaphragmatic hernia: a report of two cases

Previous studies from our institution have shown that neonates with congenital diaphragmatic hernia (CDH), whose best postductal PaO2 (BPDPO2) was less than 100 mm Hg while on maximal conventional mechanical ventilation (CMV), had a mortality exceeding 90%. When combined with extracorporeal membrane oxygenation (ECMO), the mortality rose to 100% in those infants who developed hypercarbia following decannulation. Historically, those patients have required increasing ventilator support, leading to iatrogenic lung damage, and eventual death. Intratracheal pulmonary ventilation (ITPV) using the reverse thrust catheter (RTC) developed by Kolobow incorporates a continuous flow of humidified gas through a reverse Venturi catheter positioned at the distal end of the endotracheal tube. In animal studies, ITPV was shown to result in a reduced physiological dead-space (VD), to facilitate expiration, and to enhance CO2 elimination. In our current study, we have applied ITPV in two neonates with CDH who could not be weaned from ECMO because of uncontrollable hypercapnia, and who met above criteria for 100% mortality. In both cases, ITPV restored normal PaCO2 at low peak inspiratory pressure (PIP) with a substantial decrease in VD. We believe ITPV is suited to ventilating newborns with CDH in whom barotrauma is known to be common. Beyond its present use, ITPV may be useful to ventilate children with other forms of respiratory failure, and should be so considered along with other now available methods of mechanical pulmonary ventilation.

Use of a measurement of pulmonary hyperinflation to control the level of mechanical ventilation in patients with acute severe asthma

Mechanical ventilation causes significant morbidity and mortality in patients with severe asthma. Hypoventilation may reduce this morbidity and mortality, but indicators to guide the degree of hypoventilation are unclear. We used a measure of pulmonary hyperinflation to assess the degree of airflow obstruction and to guide the extent and duration of hypoventilation. Ten patients who required mechanical ventilation for acute severe asthma were studied. All were sedated, paralyzed, and given an initial minute ventilation (VE) of 200 ml/kg/min. End-inspiratory lung volume (VEI) above FRC was measured from the total exhaled gas volume during 40 to 60 s of apnea. VEI was used to regulate VE to a safe level (VEsafe), irrespective of PaCO2, by reducing the rate when VEI was > 20 ml/kg and increasing it when VEI was < 20 ml/kg. Each patient was weaned when VEsafe resulted in PaCO2 < or = 40 mm Hg (the weaning point). FRC was measured computer analysis of anterior and lateral chest radiographs taken at the end of apnea. Using the weaning point criterion, 2 patients (PaCO2 < 40 mm Hg) were weaned shortly after arrival. The remaining eight (initial PaCO2, 63 +/- 17 mm Hg) continued hypoventilation until the weaning point was reached (30 +/- 29 h). The weaning point was reached by the VE required for PaCO2 40 mm Hg decreasing concurrent with the VEsafe increasing. All but 1 patient were successfully weaned within 24 h of the weaning point.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of exercise level on ventilatory adaptation to respirator use

The effect of exercise on the adaptation to an air-purifying respirator type load (dead space + inspiratory resistance) was studied in a group of 13 volunteers with a rapidly incremental exercise protocol. The difference between loaded and unloaded breathing at each exercise level was determined for each subject for a series of parameters describing the ventilatory work to overcome the respirator load pattern of breathing and metabolic work. Linear regression and t tests determined the average effect of the respirator load and the extent to which this effect was affected by the level of exercise. The inspiratory time and duty cycle were increased by the load, and exercise did not significantly affect the magnitude of this adaptation. High exercise did, however, increase the magnitude of the effect of the respiratory load on ventilatory work. These findings suggest that constraints to respiratory pattern adjustment, which may decrease respirator tolerance, occur at high exercise levels.

[Breathlessness of the elderly and its managements]

It is certainly difficult to understand the clinical significance of dyspnea or breathlessness among the elderly, though this symptom is quite routine. Setting a conjugate of the dyspnea index as an indicator of ventilatory reserve ratio, its distribution was tested along an age abscissa upon the twenty senile dyspnea and demonstrated almost all of them below the 30% level. Their arterial blood oxygen tensions were grouped onto the severity rank of dyspnea, clarifying that some senile lived of no complaint by the blood oxygen tensions within the range of pulmonary insufficiency, despite there some reluctant by the normal blood gas tensions. In order to comprehend this evidence, the dyspnea was dissected into several raising factors, each of which was examined the manner how a set of organs in the respiratory system of the elderly to be concerned under aging effects and to be detected in measurement. Respiratory center drive behaves in response to the efficacy of ventilation apparatus, so in resting state it supports by minimum activity without sensation of breathing difficulty, but at needs it works more even in dyspnea, the sensation of which deepens less itself together with increment of oxygen consumption. Considerable causes of this symptom for the senile may be due to hyperventilation syndrome, lung embolism after bone fracture, diabetic pulmonary capillopathy and hypophosphatemia. The treatments of senile dyspnea shall require the exact estimation of causal seriousness and not only attain improvement of pulmonary impairments and its accessory setups but also psychophysical rehabilitations upon rational nutrient preservation.

[Evaluation of mechanic characteristics of the respiratory system in artificial ventilation]

Measuring respiratory mechanics is reputed to be difficult and therefore is seldom done in intensive care units although simple techniques are available. Air flow interruption after constant rate inflation enables the total respiratory system resistance (Rrs) to be divided into airway resistance (Raw) and additional resistance (delta R), the latter being associated with the viscosity and elasticity of the respiratory system and with the inhomogeneity of the lung. Thus, in patients with chronic obstructive lung disease this end-inspiratory air flow interruption provides physiopathological data (increase of Rrs to the detriment of Raw and delta R, due to major disparities of time constants in the lung) and therapeutic data (optimum ventilation mode reducing the patient's breathing work during assisted ventilation). Air flow interruption at the end of expiration measures the intrinsic positive end-expiratory pressure which indicates hyperinflation with damaging effects on cardiac performance and respiratory muscle function and constitutes a major factor of weaning failure. Combining the end-inspiratory and end-expiratory techniques enables a realistic and complete pressure-volume curve to be drawn easily. It is therefore possible during mechanical ventilation to evaluate the characteristics of respiratory mechanics very precisely and very simply. This should improve both our understanding of some diseases and our management of ventilated patients.

Diaphragmatic displacement measured by fluoroscopy and derived by Respitrace

In eight healthy volunteers we simultaneously measured the axial diaphragmatic motion by fluoroscopy and the cross-sectional area changes of the rib cage (RC) and abdomen (ABD) by Respitrace (RIP) during semistatic vital capacities (VC). We found that, if the fluoroscopic axial displacement of the posterior part of the diaphragm between residual volume (RV) and total lung capacity (TLC) is considered equal to 100%, the movement of the middle part is 90%, whereas that of the anterior part is only approximately 60%; the ratio of the axial displacements to mouth volume, furthermore, decreases at high lung volumes, especially for the anterior part. The RIP signal is nearly linearly related to mouth volume, but the contribution of the RC (delta RC) progressively increases (and is approximately 80% RIP at TLC), whereas the volume contribution of the ABD (delta ABD) levels off (to 20% RIP at TLC). The diaphragmatic volume displacement calculated from the theoretical analysis described by Mead and Loring also levels off at high volumes similarly as the ABD but is approximately 50% RIP at TLC. Finally, the axial movements of the three parts of the diaphragm are linearly related to the RC and ABD cross-sectional-area changes (r 0.91-0.97) and are even significantly better correlated with the "calculated" diaphragmatic volume displacement.

Effects of high-frequency chest wall oscillation on respiratory control in humans

We studied the spontaneous breathing patterns of 10 normal adult volunteers during high-frequency chest wall oscillation (HFCWO), accomplished by inflating and deflating a vest worn around each subject's thorax at 2.5 Hz. Tidal volumes generated by HFCWO averaged 100 ml. Mean vest pressure was maintained at approximately 35 cm H2O throughout each experiment, even when HFCWO was not applied. During HFCWO, subjects were instructed occasionally to exhale deeply to obtain end-tidal samples representative of PACO2. HFCWO increased the breath-to-breath variability of spontaneous respiration in all subjects, prolonging expiratory pauses and producing short apneas in some cases. PACO2 decreased significantly (p less than 0.05). The effects on minute ventilation, tidal volume, and inspiratory and expiratory durations remained variable across subjects, even when differences in PACO2 between control and HFCWO states were reduced through inhalation of a low CO2 mixture. None of the changes were statistically significant, although average expiratory duration increased by 29%. Ventilatory responses to CO2 with and without HFCWO were also measured. Normocapnic (PACO2 = 40 mm Hg) ventilatory drive increased significantly (p less than 0.05) in six subjects (Type 1 response) and decreased substantially in the others (Type 2 response); with hypercapnia, the changes in drive were attenuated in both groups. Consequently, CO2 sensitivity decreased in Type 1 subjects and increased in Type 2 subjects. A simple analysis based on this result shows that with HFCWO, Type 2 subjects breathing air will tend to have a lower spontaneous minute ventilation and become hypercapnic. Type 1 subjects will become hypocapnic, but minute ventilation may be higher or lower than control.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of water temperature on pulmonary volumes in immersed human subjects

Pulmonary volumes and capacities have been measured at three water temperatures (Tw = 25, 34, 40 degrees C) in standing subjects immersed up to the shoulders. The comparison of data obtained in air with those obtained in thermoneutral immersion (Tw = 34 degrees C) confirms the results previously published in several studies. The comparison of data obtained in immersion at different Tw shows: 1. A significant decrease in vital capacity (VC) with bath temperature (VC 40 degrees C greater than VC 34 degrees C greater than VC 25 degrees C). The same decrease is observed in the inspiratory reserve volume (IRV) while the expiratory reserve volume (ERV), the residual volume (RV) and the functional residual capacity (FRC) do not vary. 2. A significant decrease in maximum breathing capacity (MBC) with bath temperature (MBC 40 degrees C greater than MBC 25 degrees C). 3. A significant increase in tidal volume (VT) in cold or hot water compared to thermoneutral water (VT40 degrees C greater than VT34 degrees C; VT34 degrees C less than VT25 degrees C) during quiet breathing. Breathing frequency does not change, thus ventilation (V) follows the same evolution as VT. The relative abdominal (ABD) contribution to VT, estimated by a double belt inductance plethysmograph, is reduced at Tw = 25 degrees C but unchanged at Tw = 40 degrees C compared to thermoneutral bath. Beside variations in the metabolic state, the variations of the pulmonary volumes as a function of Tw are estimated to be mainly due to alterations in respiratory muscles functioning.

Airway pressures during crying in healthy infants

Maximal inspiratory and expiratory airway pressures (PI max and PE max) were measured in 100 healthy infants (51 males, 49 females; age range, 0.06-3.76 years) by occluding the airway with a suitable face mask during a crying effort. Mean values +/- SD for PI max and PE max were 118 +/- 21 cm H2O and 125 +/- 35 cm H2O, respectively. Maximal inspiratory pressure was independent of age, sex, and anthropometrics, while maximal expiratory pressure showed a low but statistically significant positive correlation with body weight (P less than 0.001).

Effects of loading and unloading the respiratory system on respiratory control and muscle function

To determine the effects of internal respiratory loading and unloading on respiratory neuromuscular function, ventilatory (Vi), occlusion pressure (P0.15), transdiaphragmatic pressure (Pdi) and diaphragmatic electromyogram (EMGdi) responses to CO2 rebreathing were assessed in 6 normal volunteers rebreathing gas mixtures denser (63% SF6, 30% O2, 7% CO2) and less dense (63% He, 30% O2, 7% CO2) than air (63% N2, 30% O2, 7% CO2). Loading with SF6 decreased the Vi response to CO2 rebreathing and increased P0.15 and Pdi for a given EMGdi, while the greater the increase in pressure response the less was the decrease in Vi. Unloading with He had the opposite effect. The pattern of breathing was altered with SF6, with Ti and Te increasing and frequency decreasing, while there was no change in timing with He. Internal loading of inspiration and expiration with SF6 elicits compensatory responses that depend on changes of respiratory timing and enhanced diaphragm efficiency. Adjustments to unloading are generally opposite to that observed with loading.

The effects of aminophylline on sleep and sleep-disordered breathing in patients with obstructive sleep apnea syndrome

The methylxanthine derivatives are known to have respiratory stimulant properties. To determine whether these drugs would improve obstructive sleep apnea, 10 male patients with obstructive sleep apnea (OSA) (Apnea Index greater than 15/h) were given infusions of aminophylline and a saline placebo on 2 separate nights a week apart, using a randomized crossover design. There was a significant decrease during aminophylline infusion in the frequency of those apneas, which contained periods of complete respiratory inactivity (central and mixed apneas; placebo, 4.3 +/- 1.8/h; aminophylline, 0.7 +/- 0.5/h; p less than 0.05). There was no change in either the frequency (placebo, 31.8 +/- 5.9/h; aminophylline, 28.7 +/- 8.7/h; NS) or duration of obstructive apneas. Mean and minimal arterial oxygen saturation values were also unchanged. Sleep architecture was markedly disturbed by aminophylline. There was a reduction in sleep efficiency (placebo, 84.8 +/- 2.0%; aminophylline, 60.2 +/- 5.0%; p less than 0.005), an increase in sleep fragmentation (sleep stage shifts/h: placebo, 11.6 +/- 1.3: aminophylline, 21.0 +/- 2.9; p less than 0.05) and less Stage 2 and more Stage 1 non-REM sleep. We conclude that aminophylline reduces central apnea and the central component of mixed apneas but has no effect on obstructive apnea. Theophylline is therefore unlikely to be therapeutically useful in patients with OSA, and because it leads to marked sleep disruption, its long-term use could conceivably increase the propensity to upper airway occlusion during sleep.

Continuous positive airway pressure effect on functional residual capacity, vital capacity and its subdivisions

Thirty-four otherwise healthy patients having to undergo elective upper abdominal surgery were randomly assigned to two equal groups. In the treatment group, constant positive airway pressure (CPAP) with an expiratory pressure of 12 cm H2O was applied at one hour following extubation, and at daily intervals for the first five days following surgery for a continuous period of three hours. The control group received no CPAP treatment. All patients were given postoperative physiotherapy. In patients who received postoperative CPAP with an end-expiratory pressure of 12 cm H2O, marked normalization of pulmonary function was noted.

Breathing pattern and occlusion pressure during moderate and heavy exercise

We studied changes in breathing pattern and mouth occlusion pressure (P0.1) in 11 healthy subjects performing graded steady-state exercise on a cycle ergometer up to the maximal load sustainable for 4 min. With increasing work intensity both the tidal volume (VT) and end-inspiratory volume relations to inspiratory (TI) and expiratory (TE) durations were linear in the moderate work load range; in the high load range VT and end-inspiratory volume tended to plateau with further decreases in TI and TE. The ratio of TI to total breath duration (TI/Ttot) increased with work intensity. Intraindividual coefficients of variation for VT, breathing frequency (f), mean inspiratory flow (VT/TI), and other respiratory variables decreased with increasing work intensity, indicating that breath-to-breath variations in breathing pattern became smaller as the level of ventilation increased. P0.1 rose with VT/TI as a power function with an exponent averaging 1.5 (range 1.3-1.9), indicating that the ratio P0.1/(VT/TI), an index of respiratory system impedance, increased with VT/TI and work intensity. We conclude that in moderate and heavy exercise the work of inspiration at a given ventilation is reduced because of the increase in TI/Ttot, the impedance of the respiratory system increases with work intensity because of both an increase in f and a flow-dependent rise in airway resistance, and the neuromuscular inspiratory activity is reflexly augmented because of internal flow-resistive loading.

The immediate effect of physiotherapy and aerosol treatment on pulmonary function in children with cystic fibrosis

The direct effect of physiotherapy and physiotherapy produced by aerosol treatment on pulmonary function was studied in 25 sputum-producing patients with cystic fibrosis. Special emphasis was given to the effect on airway upstream to the flow-limiting bronchi. No significant effect on flows and volumes could be found. This may be partly explained by the fact that the percussion frequency and pressure on the chest wall with manual physiotherapy does not lead to optimal penetration of vibration in the lungs and mobilisation of secretions. Theoretically it is unlikely that any physiotherapy technique will be able to enhance the clearance of mucus from the peripheral airways.

Measurement of ventilatory reserve as an indicator for early extubation after cardiac operation

The decision to perform tracheal extubation in 44 patients who underwent cardiac operation was based on an assessment of mental alertness, recovery of muscle strength, hemodynamic stability, and adequacy of pulmonary gas exchange. No patients required reintubation. Concomitant measurements of vital capacity (VC) and maximal inspiratory pressure (PImax) were made before a trial of spontaneous ventilation was commenced, after 45 minutes of spontaneous ventilation, and after tracheal extubation. By generally accepted criteria, these measurements suggested the need for continuing mechanical ventilation in 14 patients at the time mechanical ventilatory support was removed and in eight patients at the time of tracheal extubation. In this study, consideration of measurements of VC and PImax would have led to longer trachael intubation, especially in those patients who were extubated within 10 hours of the completion of anesthesia.

[Age-dependent mechanical properties of the lung (author's transl)]

Capacity resistance breaking and volume resistance breaking were determined in normal subjects divided into three groups according to their age. There was a statistically significant age dependence with regard to both values. At a higher age, capacity resistance breaking increases in the respiratory tract already above the end-expiratory intrathoracic gas volume. There is a clear-cut age-dependent narrowing of the ventilatory reserve. This points to a relationship to "senile emphysema". It is probable that the premature loss of individual bronchi is a factor in the abnormal clearing mechanism of the elderly lung.

Lung volumes in man immersed to the neck: dilution and plethysmographic techniques

Previous studies of lung volumes during immersion have utilized dilution techniques for residual volume. We have compared lung volumes obtained by the use of a dual inert gas dilution technique with those determined by the Boyle's law technique in a plethysmograph designed to allow measurements in air and submersed to the neck in water. Both techniques gave similar results dry, but during immersion the dilution residual volume (RV) was 0.200 liter (16%) lower than the plethysmographic value (P greater than 0.001), which suggests that there is a significant amount of gas trapping during immersion due to breathing at low lung volumes and the central shift of blood. The unchanged RV due to hydrostatic force on the chest wall is balanced by the tendency to increase RV due to vascular congestion, which increases closing volume and stiffens the lung to compression.

Respiratory effects of live influenza virus vaccine: healthy older subjects and patients with chronic respiratory disease

Twenty-one healthy, middle-aged volunteers and 8 patients with chronic lung disease were given live, attenuated influenza virus vaccine by nasal spray. Forced vital capacity, 1-sec forced expiratory volume, ratio of 1-sec forced expiratory volume to forced vital capacity, residual volume, ratio of airway conductance to lung volume, maximal expiratory flows after exhalation of 50 and of 75 per cent of the forced vital capacity, closing volume, slope of Phase III, volume of isoflow, single-breath diffusing capacity for CO, and arterial blood gases were measured before and 3, 7, 10, and 21 days after exposure. Vaccination was well tolerated by the healthy volunteers without change in pulmonary function. In contrast, the patients tended to develop increased respiratory symptoms and had a slight decrease in mean forced expiratory volume in 1 sec 3 weeks after vaccination.

Effect of inspired volume on closing volume

Closing volume (CV) was ?EASURED WITH THE RESIDENT GAS TECHNIQUE IN 12 HEALTHY SEATED SUBJECTS AGE 22-70 YR, AND IN 8 SUBJECTS WITH THE BOLUS TECHNIQUE. Various volumes were inspired (Vi range: 20-100% vital capacity) from residual volume and CV was assessed on the subsequent recording of expired volume versus gas concentration. The results indicate that the resident gas technique may erroneously underestimate CV at reduced Vi in conformity with calculations which predict that during expiration, after a certain reduced VI, the nitrogen concentration is identical in the most basal lung region and at the mouth. CV obtained with the bolus technique decreased linearly with reduced Vi and the effect appeared to be age dependent according to the equation CV50/CV100=0.0078 X age +1.18, where CV50 and CV100 denote the bolus CV corresponding to Vi=50% and 100% of vital capacity. Therefore, in older subjects, during tidal breathing, airways appear to close at substantially lower lung volume than previously considered.