Effects of Loading and Unloading the Respiratory System on Respiratory Control and Muscle Function

Ginzburg, Alan S.; Lopata, Melvin; Önal, Ergün

doi:10.1159/000195701

Cited by 5 publications

(3 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Root mean square (RMS) served as an estimater of the neural phrenic drive to both hemidiaphragms. Since the amplitude of EMGdi, as quantified by RMS, indicates the phrenic in-put to the diaphragm, it can be used as a valid index of diaphragmatic neural activation [13][14][15]. It represents a statistically valid measure of the amplitude behaviour of the EMG, and thus describes the level of global muscle fibre excitation.…”

Section: Discussionmentioning

confidence: 99%

The effect of lung transplantation on the neural drive to the diaphragm in patients with severe COPD

Brath

Lahrmann²,

Wanke³

et al. 1997

Eur Respir J

View full text Add to dashboard Cite

Little is known about the effects of lung transplantation (LT) on the neural drive to the diaphragm and on the endurance of respiratory muscles in patients with severe chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate these effects of single-lung (SLT) and double-lung transplantation (DLT).The neural drive to the diaphragm was assessed during fatiguing inspiratory threshold loading manoeuvres in six SLT recipients, six DLT recipients and seven patients with severe COPD, by using diaphragmatic surface electromyograms. During threshold loading, the patients had to generate 80% of their maximal transdiaphragmatic pressure with each breath. The endurance of inspiratory muscles was defined as the time from the beginning of a resistive breathing trial until exhaustion (t lim).In DLT recipients and even in SLT recipients (on both sides), neural activation of the diaphragm was significantly lower than in COPD patients (p<0.05). However, no statistically significant difference in t lim was seen between LT recipients and COPD patients.The data suggest that single-lung and double-lung transplantations cause a significant decrease of the neural drive to the diaphragm, while the endurance of inspiratory muscles is well-preserved in patients with advanced chronic obstructive pulmonary disease. This may contribute to reduced sensation of inspiratory effort during ventilatory stress, thus improving the quality of life. Eur Respir J 1997; 10: 424-429 In a recent study, we have shown that in patients with severe chronic obstructive pulmonary disease (COPD) LT improves diaphragmatic muscle strength by placing the diaphragm in a more favourable position for generating pressure [5]. However, the effects of LT on the neural activation pattern of the diaphragm and its effects on inspiratory muscle endurance are still unknown.Therefore, the aim of this study was to evaluate the effects of LT on the neural drive to the diaphragm in patients with severe COPD during ventilatory stress induced by breathing against fatiguing threshold loads.We also intended to determine the effects of LT on the endurance of inspiratory muscles by analysing the timespan from the beginning of the resistive breathing tests until exhaustion. Methods PatientsTwelve LT recipients (six SLT recipients (3 males and 3 females), and six DLT recipients (3 males and 3 females)), and seven patients with severe COPD prior to transplantation (4 males and 3 females) entered the study. Two SLT recipients (1 male and 1 female) and two DLT recipients (1 male and 1 female) were also studied preand postoperatively. All LT recipients had transplantation because of severe emphysema. One SLT recipient and one COPD patient had α 1 -antitrypsin deficiency emphysema. The lung function parameters of the COPD patients were similar to those of the LT recipients preoperatively. They were characterized by chronic airflow obstruction (forced expiratory volume in one second (FEV1) <40% predicted, ratio of FEV1 to forced vital

show abstract

Section: Discussionmentioning

confidence: 99%

The effect of lung transplantation on the neural drive to the diaphragm in patients with severe COPD

Brath

Lahrmann²,

Wanke³

et al. 1997

Eur Respir J

View full text Add to dashboard Cite

show abstract

“…In addition, for each subject the slopes of VE vs Pdi (AVE/APdi) and those of diaphragmatic EMG vs Pdi (AEMGdi/APdi) were calculated using the least squares linear regression method, and the respective correlation coefficients were determined. The latter relationship (AEMGdi/APdi) was used as an index of diaphragmatic neuromuscular coupling, reflecting the neuromechanical efficiency of the diaphragm [7,11,29]. All data samples before and after draining the dialysate were compared statistically using the nonparametric Wilcoxon-test for paired samples.…”

Section: Discussionmentioning

confidence: 99%

“…EMGdi obtained with this method has been shown to be a reliable index of respiratory neural response to CO2-rebreathing [17] and hypoxia [18]. Since EMGdi indicates the neurogenic input into the diaphragm, and Pdi is an acceptable index of the mechanical output of the diaphragm, the ratio EMGdi/Pdi can be used as a valid index of the neuromechanical efficiency of the diaphragm [7,11,29].…”

Section: Discussionmentioning

confidence: 99%

Diaphragmatic function in patients on continuous ambulatory peritoneal dialysis

Wanke

Auinger

Lahrmann

et al. 1994

Lung

View full text Add to dashboard Cite

We investigated 8 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) for diaphragmatic strength and the neuromechanical efficiency of the diaphragm while the abdomen was filled with dialysate and while it was empty. Maximum transdiaphragmatic pressure (Pdimax) served as parameter for diaphragmatic strength; diaphragmatic efficiency was assessed by simultaneously monitoring transdiaphragmatic pressure (Pdi) and diaphragmatic electromyogram (EMGdi) during room-air breathing and hyperoxic CO2-rebreathing. After instilling dialysate, Pdimax increased from 76.7 +/- 12.1 cmH2O to 92.2 +/- 16.3 cmH2O (P < 0.05). While the slopes of the regression lines relating minute ventilation (VE) to arterial CO2 tension, and the change in VE for a given change in Pdi during hypercapnic rebreathing were similar in both states, the slope of EMGdi vs Pdi was significantly steeper when the abdomen was filled (P < 0.05). The increase in Pdimax observed in the filled state may suggest an adaptive rightward shift in the diaphragm's force-length relationship in CAPD patients, although this mechanism is insufficient to prevent a reduction of neuromechanical efficiency of the diaphragm.

show abstract

Ventilatory adjustments during sustained resistive unloading in exercising humans

Maillard

Delpuech

Hatzfeld

1990

Europ. J. Appl. Physiol.

View full text Add to dashboard Cite

Effect of He-O2-breathing (79.1%:20.9%) compared to air-breathing on inspiratory ventilation (VI) and its different components [tidal volume (VT), the duration of the phases of each respiratory cycle (tI, tTOT)] as well as on inspiratory mouth occlusion pressure (P0.1) were studied in six normal men at rest and during 72 constant-load exercises (90 W) over a much longer period than in previous studies. Results showed that, irrespective of the order of administration of the two gases (7 min air----7 min He-O2 or vice versa): at rest, P0.1 decreased during He-O2 inhalation but no changes in VI and breathing pattern were detectable; during exercise, sustained He-induced hyperventilation was observed without any change in the absolute value of P0.1; increase in P0.1 between the resting period and exercise (delta P0.1) was significantly higher during He-O2-breathing than during air breathing; this He-induced hyperventilation was associated with a sustained increase in VT/tI, but with constant tI/tTOT. Helium-breathing during exercise cannot be a simple situation of resistance unloading, as has been suggested. We conclude that He-O2-breathing, after the initial compensation period, induces reflex changes in ventilatory control with an increase in inspiratory neural drive. Moreover, it appears that exercise P0.1 is not a legitimate index of inspiratory neural drive whenever rest P0.1 changes according to the nature of the inhaled gas mixture.

show abstract

Effects of Loading and Unloading the Respiratory System on Respiratory Control and Muscle Function

Cited by 5 publications

References 19 publications

The effect of lung transplantation on the neural drive to the diaphragm in patients with severe COPD

The effect of lung transplantation on the neural drive to the diaphragm in patients with severe COPD

Diaphragmatic function in patients on continuous ambulatory peritoneal dialysis

Ventilatory adjustments during sustained resistive unloading in exercising humans

Contact Info

Product

Resources

About