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PubMed1985

Precurarization with vecuronium and pancuronium in awake, healthy volunteers: the influence on neuromuscular transmission and pulmonary function.

The influence of pretreatment with pancuronium and vecuronium on the neuromuscular transmission was compared in 24 healthy, awake, non-premedicated volunteers using train-of-four (TOF) nerve stimulation and measurement of respiratory frequency, vital capacity, inspiratory force and peak expiratory flow (PEF). The subjects were randomly allocated to one of three groups. Each subject received one dose of pancuronium and one dose of vecuronium: Group I pancuronium 0.01 mg/kg and vecuronium 0.005 mg/kg; Group II pancuronium 0.01 mg/kg and vecuronium 0.01 mg/kg and Group III pancuronium 0.01 mg/kg and vecuronium 0.015 mg/kg intravenously. The median TOF ratio decreased significantly in Groups I and II following both pancuronium and vecuronium. The TOF ratio following vecuronium in Group II was significantly lower compared to the TOF ratio following vecuronium in Group I. Only PEF decreased significantly in Group I following pancuronium and in Group II following both pancuronium and vecuronium. There was no significant difference between Group I and Group II regarding the number of subjects with signs or symptoms of partial neuromuscular blockade. Following vecuronium 0.005 mg/kg, one subject was unable to swallow and the twitch height decreased to 0.25. In Group II one subject was unable to lift her head and had difficulty in swallowing following pancuronium 0.01 mg/kg. Only four subjects entered Group III because of an unacceptably high frequency of signs and symptoms of partial neuromuscular blockade and a decrease in median TOF ratio to 0.64 following vecuronium. The subjects felt it difficult to swallow, and one subject could just sustain head lift for 10 s following vecuronium 0.015 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Consciousness↗
PubMed2003

Correlation between standing height, sitting height, and arm span as an index of pulmonary function in 6-10-year-old children.

The present study evaluates the relationships of pulmonary volumes and flows and the anthropometric variables of standing height, sitting height, and arm span in 100 6-10-year-old children. To be included in the study, all children were required to be healthy and above the 3rd percentile of the curve of Tanner et al. (Arch Dis Child 1966;41:454-471; Arch Dis Child 1966;41:613-635) for height and weight. Standing height, sitting height, and arm span were measured according to standard protocol. The pulmonary function measurements were: tidal volume, minute respiratory volume, respiratory rate, expiratory reserve volume, inspiratory capacity, vital capacity, residual volume (RV), functional residual capacity, total lung capacity (TLC), forced vital capacity (FVC), forced expiratory volume in 1 sec of FVC (FEV(1)), forced expiratory flow measured between 25-75% of FVC, and FEV(1)/FVC and RV/TLC ratios. Simple linear regression best expressed the correlation between pulmonary function and the anthropometric variables. Significant correlations between anthropometric and pulmonary function measurements were observed, with FVC and FEV(1) showing the highest and RV the lowest r(2) values. There was a significant positive correlation between standing height and arm span according to linear regression and Bland-Altman comparison (Bland and Altman, Lancet 1968;8:307-310). Our results suggest that when an accurate determination of standing height cannot be obtained, arm span could be used interchangeably, using the same regression equation. However, for patients with limb deformities, regression equations of pulmonary function measurements in relation to sitting height may be a better choice for estimating pulmonary function.

Anthropometry↗
PubMedDate not supplied

Endothelin-1 expression during early response after antigen challenge in brown-norway rats.

The objective of this study is to investigate if endothelin-1 (ET-1) gene expression changes during the early response phase following antigen challenge. We used sensitized Brown-Norway rats known to develop an early airway response after antigen challenge. After ovalbumin challenge, sensitized rats presented an early response, characterized by an increase in pulmonary pressure (209+/-14.53%,P<0. 01) and diminished functional parameters (inspiratory capacity, forced vital capacity (FVC) and expiratory flow at 75% of FVC), compared to their respective basal values. ET-1 mRNA expression was assessed by reverse transcription and polymerase chain reaction using specific primers for prepro-ET-1. A group of unsensitized rats was used as control. ET-1 expression was significantly enhanced in sensitized rats during the early response (290+/-62%,P<0.01) compared to the control group. In conclusion, antigen challenge induces an activation of ET-1 gene expression during the early response in Brown-Norway rats, suggesting a contribution of this protein to the development of bronchoconstriction.

Animals↗
PubMed2006

[Therapeutic goals and outcome measurements in COPD patients].

Due to the complex pathogenesis of chronic obstructive pulmonary disease (COPD) with systemic effects and different subjective perceptions, responses to therapy are difficult to assess. Though lung function tests correlate poorly with important features of the disease such as survival and quality of life, spirometric measures, especially forced expiratory volume (FEV(1)) and inspiratory capacity, the 6-min walk test, exacerbation indices, dyspnea scales and health status measurements remain important outcomes in clinical studies as well as in clinical practice. Markers of airway inflammation are receiving increased attention. The BODE index, combining functional and systemic outcomes, is a better predictor of mortality than FEV(1) and, therefore, particularly valuable.

Adult↗
PubMedDate not supplied

Respiratory muscles and dyspnea in obese nonsmoking subjects.

To our knowledge no data have been reported on the contribution to acute increase in dyspnea by the respiratory muscles in obese nonsmoking subjects. To better focus on this topic, we studied seven obese subjects and an age-matched normal control group, assessing baseline pulmonary function, breathing pattern, esophageal pressure (Pes), and gastric (Pga) and transdiaphragmatic (Pdi) pressures. Pes was also recorded during a sniff maneuver (Pessn). During a hypercapnic rebreathing test we recorded inspiratory swing in Pes (Pessw), expiratory changes in Pga, and inspiratory swings in Pdi (Pdisw). Change in inspiratory capacity was considered the mirror image of end-expiratory lung volume (EELV). Dyspnea was assessed by a modified Borg scale. Under control conditions, patients exhibited a reduced expiratory reserve volume and intrinsic positive end-expiratory pressure (PEEPi). At the end of hypercapnic stimulation, compared with controls our obese subjects exhibited greater respiratory frequency (Rf), shorter expiratory time, greater Pessw, and lower Pdisw. Increases in EELV and PEEPi were found in the obese subjects but not in controls. Changes in Borg correlated with changes in PETCO2, VE, Pessw (%Pessn), and Pdisw to a greater extent in patients than in controls. Stepwise regression analysis indicated the amount of variability in Borg that was predicted by both Pdisw (r2 = 0.31, p < 0.0004), and Pessw (%Pessn) (r2 = 0.09, p < 0.005) in controls, and by Pessw (%Pessn) (r2 = 0.40, p < 0.00001) in obese subjects. We conclude that the rib cage muscles contributed to dyspnea to a greater extent in this subset of obese subjects.

Adult↗
PubMedDate not supplied

A controlled trial of the effects of leg training on breathing pattern and dynamic hyperinflation in severe COPD.

The effects of training on dynamic hyperinflation in stable chronic obstructive pulmonary disease (COPD) were investigated by using a controlled study of 28 subjects with FEV(1) = 42.5 (8.3 SD)%pred and 20 matched controls [FEV(1) = 44.9 (10.4)%pred]. Training consisted of spending 45 min/day, 4 days/week on a cycle-ergometer for six weeks. Maximal inspiratory and expiratory pressures (MIP and MEP), lung volumes, and two constant-work-rate (CWR) exercise tests (low- and high-intensity) were performed. Significant (p < 0.0l) improvements in the training group were observed in MIP [+8 (12) cmH(2)O], MEP [+18 (20) cmH(2)O], and endurance to high-intensity CWR [+7(5) min], and there were significant decreases in respiratory rate and end-expiratory lung volume (EELV) during both exercise tests. At 5 min, EELV decreased 0.1(0.08) L and 0.31(0.13) L and at end of exercise, EELV decreased by 0.09(0.07) L and 0.15(0.11) L respectively, for the moderate- and high-intensity tests. Dyspnea also decreased significantly at both exercise intensities. No changes were observed in the control group. Increased endurance showed independent significant (p < 0.05) correlation with changes in EELV, leg fatigue, and MEP. EELV changes showed a significant negative correlation with resting inspiratory capacity. We conclude that exercise training has beneficial effects on respiratory pattern and dynamic hyperinflation that may partially explain the reduction in dyspnea and the improvement in exercise tolerance.

Aged↗
PubMed2001

Expiratory muscle endurance in middle-aged healthy subjects.

To evaluate expiratory muscle endurance in middle-aged healthy subjects using incremental as well as constant expiratory loads, 14 healthy volunteers (51 +/- 16 years) were submitted to a specific endurance test, which was performed breathing against a threshold valve, and was divided into two parts. In part I, the load was progressively increased (50 g each 2 min) until task failure occurred. The mean mouth pressure generated against the highest load held for at least 60 sec was defined as the maximal expiratory sustainable pressure (Pth(max)). In part II, each subject breathed against a constant submaximal expiratory load (80% Pth(max)) until task failure occurred (expiratory endurance time or Tth(80)). Both parts of the test were repeated 24-48 h later. Progressive expiratory loading induced a linear increase in mouth expiratory pressure and the Pth(max) obtained was 141 +/- 43 cm H(2)O, representing 74 +/- 28% of the maximal expiratory pressure (PE(max)). Under constant loads, the Tth(80) was 17 +/- 9 min. At the end-point of both parts, the tension time index for expiratory muscles was dramatically increased (>0.25), and both EMG central frequency and PE(max) were decreased with no changes in maximal inspiratory pressure or inspiratory capacity. Extreme dyspnea was present in most of the subjects but no complications were observed. The endurance of expiratory muscles can be easily assessed in healthy subjects using this method, which has acceptable reproducibility and tolerance.

Airway Resistance↗
PubMed2004

Respiratory kinematics by optoelectronic plethysmography during exercise in men and women.

Gender differences in resting pulmonary function are attributable to the smaller lung volumes in women relative to men. We sought to investigate whether the pattern of response in operational lung volumes during exercise is different between men and women of similar fitness levels. Breath-by-breath volume changes of the entire chest wall ( V(.)( CW)) and its rib cage ( V(.)( Rc)) and abdominal ( V(.)( Ab)) compartments were studied by optoelectronic plethysmography in 15 healthy subjects (10 men) who underwent a symptom-limited ( W (peak)) incremental bicycle test. The pattern of change in end-inspiratory and end-expiratory V(.)( CW) ( V(.)( CW,EI) and V(.)( CW,EE), respectively) did not differ between the sexes. With increasing workload the decrease in V(.)( CW,EE) was almost entirely attributable to a reduction in end-expiratory V(.)( Ab), whereas the increase in V(.)( CW,EI) was due to the increase in end-inspiratory V(.)( Rc) in both sexes. In men, at W (peak) tidal volume [ V(.)( T), 2.7 (0.2) l] and inspiratory capacity [IC, 3.4 (0.2) l] were significantly greater than in women [1.8 (0.2) and 2.6 (0.2) l, respectively]. However, after controlling for lung size using forced vital capacity (FVC) as a surrogate, the differences between men and women were eliminated [ V(.)( T) /FVC 49 (3) and 45 (3) respectively, and IC/FVC 63 (2) and 65 (3) respectively]. All data are presented as mean (SE). In both men and women the contribution of the rib cage compartment to V(.)( T) expansion was significantly greater than that of the abdominal compartment. We conclude that gender differences in operational lung volumes in response to progressive exercise are principally attributable to differences related to lung size, whereas compartmental chest wall kinematics do not differ among sexes.

Adult↗
PubMed1981

Cranio-caudal rib cage distortion with increasing inspiratory airflow in man.

Changes in anteroposterior and transverse diameters of the chest wall, in cranial and caudal esophageal pressure (delta Pes), and diaphragm (Adi) and cranial intercostal muscle activity (Aic) were measured in supine and seated subjects during relaxation and full inspirations from FRC at constant slow or high flow rates. No distortion of the rib cage occurred during relaxation of slow inspirations. During fast inspirations cranial part of rib cage expanded relatively more than caudal one because of greater Aic for any level of Adi. Rib cage distortion during fast inspirations, as well as the occurring between seated and supine posture, was directionally consistent with flow or posture related redistribution of apicobasal lung expansion, suggesting that changes in rib cage shape affect regional lung expansion also in man. During relaxation or slow inspirations cranio-caudal difference in delta Pes (delta Pc-c) was essentially nil over all the inspiratory capacity. During fast inspirations delta Pc-c was negative (seated posture) or nil (supine posture) for small lung volume increments, positive for large volume increments. Delta Pc-c dependence on lung volume is compatible with the response of a model consisting of two parallel compartments with different degree of expansion at FRC and equal volume dependent mechanical properties.

Diaphragm↗
PubMed1989

Does lung function limit performance in a 24-hour ultramarathon?

Based on observations of impaired lung function after marathon and ultramarathon running, it was hypothesized that the decline in running speed during a 24-h ultramarathon may be explained, in part, by ventilatory muscle fatigue. To test this hypothesis, ten competitors in the 1988 TAC/USA National 24-h Championship performed a battery of pulmonary function tests every 3 h during the race. The tests included measurement of inspiratory capacity, peak flow, forced vital capacity, forced expiratory volume in 1 sec, maximum voluntary ventilation for 12 sec (MVV12), and maximal respiratory pressures. Running speed was averaged over 3-h periods. MVV12 was significantly decreased (17%), but only after 24 h of running. All other ventilatory measures tended to decrease over time but the changes were not significant. However, after correcting for between-subject differences in running speed, the variance in MVV12 accounted for 39% (P less than 0.0001) of the variance in running speed. It was concluded that the decrease in ventilatory muscle endurance may constrain running speed in extremely prolonged running events.

Adult↗
PubMed1988

Comparison of daily and seasonal exposures of young monkeys to ozone.

Oxidant air pollution tends to occur in both seasonal and daily cycles of polluted and clean air. To compare the effects of these 2 cycles, we exposed 2 groups of 7-month-old male monkeys to 0.25 ppm (0.49 mg/m3) of ozone (UV photometric standard) 8 h/day either daily or, in the seasonal model, days of alternate months during a total exposure period of 18 months. This is a longer ozone exposure period than any previously reported. A control group breathed only filtered air. Young monkeys were studied as their lungs are similar to those of man and their lungs, like those of man, grow over a period of several years. Monkeys from the seasonal exposure model, but not those exposed daily, had significantly increased total lung collagen content, chest wall compliance, and inspiratory capacity. All monkeys exposed to ozone had respiratory bronchiolitis with significant increases in related morphometric parameters. The only significant difference between seasonal and daily groups was in the volume fraction of macrophages. Even though the seasonally exposed monkeys were exposed to the same concentration of ozone for only half as many days, they had larger biochemical and physiological alterations and equivalent morphometric changes as those exposed daily. Lung growth was not completely normal in either exposed group. Long-term effects of oxidant air pollutants which have a seasonal occurrence may be more dependent upon the sequence of polluted and clean air than on the total number of days of pollution. Estimations of the risks of human exposure to seasonal air pollutants from effects observed in animals exposed daily may underestimate long-term pulmonary damage.

Air Pollutants↗
PubMed1988

Ventilatory responses to hypercapnia during tetracaine spinal anesthesia.

The effect of spinal anesthesia with hyperbaric tetracaine with epinephrine on resting ventilation and on ventilatory responsiveness to CO2 rebreathing was studied in 10 unpremedicated patients. Resting end-tidal PCO2 (PETCO2) decreased from 37 +/- 3 mmHg (mean +/- SD) to 34 +/- 2 mmHg after induction of spinal anesthesia (p less than 0.05). Minute ventilation (VE) and occlusion pressure (P0.1) at PETCO2 = 55 mmHg increased during spinal anesthesia from 32.0 +/- 12.9 to 40.2 +/- 17.0 l/min and from 5.0 +/- 1.8 to 8.6 +/- 4.7 cmH2O, respectively. The magnitude of the increase in VE during spinal anesthesia correlated inversely with age. Spinal anesthesia was not associated with significant changes in vital capacity, maximal inspiratory pressure, or the slopes of the lines relating VE or P0.1 to PCO2. These results show increased ventilatory responsiveness to CO2 (a parallel leftward shift of the CO2 response curve) with tetracaine spinal anesthesia.

Adult↗
PubMed2006

Temporal profile of forced expiratory lung function in allergen-challenged Brown-Norway rats.

The Brown-Norway rat is often used to study the allergic pulmonary response. However, relatively little is known about the delayed phase reactions after allergen challenge in this species. To evaluate the temporal changes in lung function and elucidate the mechanisms involved in the delayed phase response, Brown-Norway rats were sensitized and challenged to aerosolized ovalbumin and lung functions were measured by forced expiratory maneuvers and forced oscillation for up to 10 days after a single antigen challenge. Statistically significant (P < 0.05) reductions in inspiratory capacity, forced vital capacity, functional residual capacity, peak expiratory flow and maximum mid-expiratory flow and increases in respiratory system resistance and elastance were seen by 1 to 3 days after ovalbumin challenge that returned to baseline by 10 days. The reductions in lung function after ovalbumin challenge were blocked by the corticosteroid, betamethasone (1 mg/kg, p.o.). Histological evaluation of lung tissue of sensitized rats demonstrated evidence of interstitial pulmonary edema, an increase in tissue eosinophils and an increase in Periodic Acid Schiff-positive cells in the airway epithelium. Bronchoalveolar lavage fluid samples showed large numbers of eosinophils and increased mucin content up to 6 days after antigen challenge. There was also an increase in wet-to-dry lung weight ratio in the lungs of sensitized rats after antigen. These results demonstrate that prolonged reductions in lung function occur after a single antigen challenge in Brown-Norway rats that is probably due to inflammatory processes producing interstitial pulmonary edema, mucus secretion and cellular influx into the lungs.

Allergens↗
PubMed2005

Cough determinants in patients with neuromuscular disease.

Neuromuscular disease leads to cough impairment. Cough augmentation can be achieved by mechanical insufflation (MI) or manually assisted coughing (MAC). Many studies have compared these two methods, but few have evaluated them in combination. In 155 neuromuscular patients, we assessed determinants of peak cough flow (PCF) using stepwise correlation. Maximal inspiratory capacity contributed 44% of the variance (p<0.001), expiratory reserve volume 13%, and maximal expiratory pressure 2%. Thus, augmenting inspiration seems crucial. However, parameters dependent on expiratory muscles independently influence PCF. We measured vital capacity and PCF in 10 neuromuscular patients during cough augmentation by MI, MAC, or both. MI or MAC significantly improved VC and PCF (p<0.01) as compared to the basal condition and VC and PCF were higher during MI plus MAC than during MAC or MI alone (p<0.01). In conclusion, combining MAC and MI is useful for improving cough in neuromuscular patients.

Adolescent↗
PubMed1998

Postnatal development of respiratory function in lambs studied serially between birth and 8 weeks.

We have quantified developmental changes in major aspects of respiratory function in 12 pentobarbitone-sedated lambs by making repeated measurements during the first 8 postnatal weeks, between term birth and post-weaning. Pulmonary diffusing capacity for CO increased with age due to increases in both the diffusing capacity of the alveolar capillary membrane (Dm) and pulmonary capillary blood volume (Vc). Total lung capacity measured at a lung inflation pressure of 30 cmH2O decreased from 74.4 +/- 3.2 ml/kg at 3 days to 47.2 +/- 2.9 ml/kg at 8 weeks. Static respiratory system compliance, measured between FRC and TLC fell rapidly during the first 3 weeks, then remained unchanged; the early postnatal fall was largely due to a reduction in chest wall compliance as lung compliance was constant. FRC declined from 32.3 +/- 1.7 ml/kg at 3 days to 25.1 +/- 1.5 ml/kg at 2 weeks, then fell to 21.4 +/- 1.2 ml/kg by 8 weeks. Specific pulmonary conductance (conductance/FRC) during mid-inspiration and mid-expiration did not change with age (0.195 +/- 0.012 and 0.194 +/- 0.019 L x sec(-1) x cmH2O(-1) x L(-1)-FRC, respectively). Breathing frequency, and weight-adjusted tidal volume and minute ventilation declined after birth until 4 weeks after which they did not change. This study has shown that, using basic methodology, serial assessments of respiratory function can be obtained in sedated lambs from soon after birth. The age-related increase seen in pulmonary diffusing capacity is due to increases in both Dm and Vc, which are consistent with continuing alveolarisation. Our data on age-related changes in pulmonary function and volumes provide a reference for future studies on the effect of altered prenatal lung development on postnatal lung function in sheep.

Aging↗
PubMed2002

Formoterol as dry powder oral inhalation compared with salbutamol metered-dose inhaler in acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: Acute exacerbations of chronic obstructive pulmonary disease (COPD) are managed with increased doses or frequency of the patient's existing bronchodilator therapy. The use of formoterol in the treatment of mild acute exacerbations of COPD has been suggested; however, a comparison of cumulative doses of formoterol with salbutamol, the gold standard bronchodilator agent for this pathologic condition, is still lacking. OBJECTIVE: The aim of the study was to compare the inhaled beta2-agonists salbutamol (rapid onset, short duration of action) and formoterol (rapid onset, long duration of action), both used as needed in patients attending outpatient clinics because of mild acute exacerbations of COPD (Anthonisen exacerbation type I or II). METHODS: A dose-response curve to formoterol via Turbuhaler or salbutamol via pressurized metered-dose inhaler (pMDI) was constructed. On 2 consecutive days, the patients received, in randomized order, both of the following active dose regimens: A = 12 + 12 + 24 microg formoterol via Turbuhaler (48-microg cumulative metered dose); B = 200 + 200 + 400 microg salbutamol via pMDI (800-microg cumulative metered dose). Dose increments were given at 30-minute intervals, with measurements made 25 minutes after each dose. The maximum forced expiratory volume in 1 second (FEV1) value during the dose-response curve to formoterol or salbutamol was chosen as the primary outcome variable to compare the 2 treatments. Oxygen saturation by pulse oximetry (SpO2) and pulse rate were also measured at each assessment period. Every adverse event, either reported spontaneously by the patients or observed by the investigators, was recorded. RESULTS: Sixteen patients (2 women, 14 men) aged 51 to 77 years (most older than 65 years) participated in the study. Both formoterol and salbutamol induced a large, significant, dose-dependent increase in FEV1, inspiratory capacity (IC), and forced vital ca- pacity (FVC). There was no significant difference between FEV1, IC, and FVC values after 48 microg formoterol and 800 microg salbutamol. There was no significant difference in FEV1 after 24 microg formoterol and 800 microg salbutamol; however, the difference in FEV1 after 24 and 48 microg formoterol was significant. Neither heart rate (mean differences from baseline after 48 microg formoterol, 1.9 beats/min [95% CI, -3.4, 7.2] and 800 microg salbutamol, 3.7 beats/min [95% CI, -1.1, 8.5]) nor SpO2 (mean percentage differences from baseline after 48 microg formoterol, -0.37% [95% CI, -1.22, 0.47] and 800 microg salbutamol, -0.75% [95% CI, -1.73, 0.23]) changed significantly. However, SpO2 decreased below 90% in 2 patients after the highest dose of formoterol and in 1 patient after the highest dose of salbutamol. CONCLUSIONS: In this small, selected group of patients with mild acute exacerbations of COPD, formoterol via Turbuhaler induced a fast bronchodilation that was dose dependent and not significantly different from that caused by salbutamol. Furthermore, formoterol appeared to be as well tolerated as salbutamol.

Administration, Inhalation↗
PubMed2001

Effects of inhalatory abdominal wall movement on vertical laryngeal position during phonation.

The configuration of the body resulting from inhalatory behavior is sometimes considered a factor of relevance to voice production in singing and speaking pedagogy and in clinical voice therapy. The present investigation compares two different inhalatory behaviors: (1) with a "paradoxical" inward movement of the abdominal wall, and (2) with an expansion of the abdominal wall, both with regard to the effect on vertical laryngeal position during the subsequent phonation. Seventeen male and 17 female healthy, vocally untrained subjects participated. No instructions were given regarding movements of the rib cage. Inhaled air volume as measured by respiratory inductive plethysmography, was controlled to reach 70% inspiratory capacity. Vertical laryngeal position was recorded by two-channel electroglottography during the subsequent vowel production. A significant effect was found; the abdomen-out condition was associated with a higher laryngeal position than the abdomen-in condition. This result apparently contradicted a hypothesis that an expansion of the abdominal wall would allow the diaphragm to descend deeper in the torso, thereby increasing the tracheal pull, which would result in a lower laryngeal position. In a post-hoc experiment including 6 of the subjects, body posture was studied by digital video recordings, revealing that the two inhalatory modes were clearly associated with postural changes affecting laryngeal position. The "paradoxical" inward movement of the abdominal wall was associated with a recession of the chin toward the neck, such that the larynx appeared in a lower position in the neck, for reasons of a postural change. The results suggest that the laryngeal position can be affected by the inhalatory behavior if no attention is paid to posture, implying that instructions from clinicians and pedagogues regarding breathing behavior must be carefully formulated and adjusted in order to ensure that the intended goals are reached.

Abdominal Muscles↗
PubMed2003

A lung recruitment maneuver immediately before rescue surfactant therapy does not affect the lung mechanical response in immature lambs with respiratory distress syndrome.

BACKGROUND: In animals with acquired surfactant-deficiency, a recruitment maneuver by increased tidal volumes enhances the effect of exogenous surfactant. In contrast, in the preterm lamb model, hyperinflation early after birth impairs the effect of surfactant prophylaxis. Here we examined whether a lung recruitment maneuver just before surfactant would affect the response to rescue treatment in immature lambs with established respiratory distress syndrome (RDS). METHODS: Five pairs of preterm twin lambs with gestational age 127 days were delivered by cesarean section and supported by pressure-limited mechanical ventilation for 4 h. At 30 min of age, when all the lambs were in severe respiratory failure, they were treated with porcine surfactant, 200 mg x kg-1. One lamb in each pair was subjected to a lung recruitment maneuver consisting of five sustained inflations of 20 ml x kg-1 just before surfactant instillation. RESULTS: At 10 min after surfactant treatment, all the lambs showed a large improvement in oxygenation and an increase in inspiratory capacity and static compliance. Except for a transiently better oxygenation after surfactant therapy in the recruitment group (P < 0.05), there was no significant between-group differences in gas exchange or lung mechanics at any time point during the study. There was no difference in post mortem intrapulmonary air volume or alveolar expansion in histologic lung sections between groups. CONCLUSION: This small study does not show any positive or negative effect of a lung recruitment maneuver on the response to rescue surfactant therapy in immature animals with RDS.

Animals↗