Electrical and mechanical activity of respiratory muscles during hypercapnia

1986 ◽  
Vol 61 (2) ◽  
pp. 719-727 ◽  
Author(s):  
E. van Lunteren ◽  
N. S. Cherniack
Keyword(s):  
Moving Average ◽  
Respiratory Muscles ◽  
Mechanical Activity ◽  
Intercostal Muscles ◽  
Co2 Rebreathing ◽  
Single Breath ◽  
Linear Relationships ◽  
Muscle Shortening ◽  
Close Relationship ◽  
Spontaneously Breathing

In nine anesthetized supine spontaneously breathing dogs, we compared moving average electromyograms (EMGs) of the costal diaphragm and the third parasternal intercostal muscles with their respective respiratory changes in length (measured by sonomicrometry). During resting O2 breathing the pattern of diaphragm and intercostal muscle inspiratory shortening paralleled the gradually incrementing pattern of their moving average EMGs. Progressive hypercapnia caused progressive increases in the amount and velocity of respiratory muscle inspiratory shortening. For both muscles there were linear relationships during the course of CO2 rebreathing between their peak moving average EMGs and total inspiratory shortening and between tidal volume and total inspiratory shortening. During single-breath airway occlusions, the electrical activity of both the diaphragm and intercostal muscles increased, but there were decreases in their tidal shortening. The extent of muscle shortening during occluded breaths was increased by hypercapnia, so that both muscles shortened more during occluded breaths under hypercapnic conditions (PCO2 up to 90 Torr) than during unoccluded breaths under normocapnic conditions. These results suggest that for the costal diaphragm and parasternal intercostal muscles there is a close relationship between their electrical and mechanical behavior during CO2 rebreathing, this relationship is substantially altered by occluding the airway for a single breath, and thoracic respiratory muscles do not contract quasi-isometrically during occluded breaths.

Mechanics of the parasternal intercostals in prone dogs: statics and dynamics

1993 ◽  
Vol 74 (6) ◽  
pp. 2757-2762 ◽  
Author(s):  
A. De Troyer ◽  
G. Farkas
Keyword(s):  
Mechanical Behavior ◽  
Inspiratory Muscle ◽  
Emg Activity ◽  
Relaxation Length ◽  
Intercostal Muscles ◽  
Muscle Shortening ◽  
Statics And Dynamics ◽  
Tension Curve ◽  
Spontaneously Breathing ◽  
Prone Posture

It is well established that the parasternal intercostal muscles in supine dogs play a major role in causing the inspiratory elevation of the ribs. This posture, however, is not physiological in the dog. In the present study, we measured the electromyographic (EMG) activity and the respiratory changes in length of these muscles in the prone (standing) and supine postures in seven anesthetized spontaneously breathing dogs. With a change from the supine to the prone posture, the parasternal intercostals showed a 3.2% reduction in their relaxation length (Lr), but their mechanical behavior was essentially unchanged. Thus, the muscles continued to shorten below Lr during inspiration and to lengthen beyond Lr during expiration. With the adoption of the prone posture, the amount of parasternal inspiratory EMG activity and the amount of inspiratory muscle shortening each increased by 30–35%. Furthermore, when the parasternal intercostal in a single interspace was selectively denervated, the shortening of the muscle during inspiration in both postures was virtually eliminated. These observations indicate that in the dog the parasternal intercostals still play a major role in causing the inspiratory elevation of the ribs in the prone posture. These observations also suggest that these muscles in prone animals continue to operate on the descending limb of their length-tension curve.

Quantification of diaphragmatic EMG response to CO2 rebreathing in humans

1977 ◽  
Vol 43 (2) ◽  
pp. 262-270 ◽  
Author(s):  
M. Lopata ◽  
M. J. Evanich ◽  
R. V. Lourenco
Keyword(s):  
Moving Average ◽  
Minute Ventilation ◽  
Respiratory Muscles ◽  
Correlation Coefficients ◽  
Total Activity ◽  
Co2 Rebreathing ◽  
Significant Difference ◽  
Inspiratory Activity ◽  
Normal Males ◽  
Integration Area

To determine a reliable quantitative method of measuring diaphragmatic EMG (EMGdi), electrical activity of the diaphragm was obtained via an esophageal electrode during CO2 rebreathing in 6 normal males and processed three different ways: 1) integration (area), 2) as a moving time average, and 3) as a moving time variance. Integrated activity was quantified in terms of total activity and inspiratory activity. In addition, average total activity and average inspiratory activity were calculated. Moving average and moving variance were analyzed in terms of rate of rise (slope) and peak activities. All integration parameters, except average inspiratory activity, were poorly correlated to changes in PCO2, minute ventilation, and inspiratory muscle force, during rebreathing. Moving average and variance responses to rebreathing were linear with high correlation coefficients, with the slope measures showing the overall best correlations. There was no significant difference between average and variance EMGdi parameters in their responses to rebreathing. Time-related quantification of EMGdi, including average inspiratory activity, and particularly moving average and moving variance, appear to be reliable methods for quantitating neural drive to the respiratory muscles during CO2 rebreathing.

Effects of bronchoconstriction on respiratory muscle activity during expiration

1987 ◽  
Vol 62 (1) ◽  
pp. 308-314 ◽  
Author(s):  
A. Oliven ◽  
E. C. Deal ◽  
S. G. Kelsen ◽  
N. S. Cherniack
Keyword(s):  
Electrical Activity ◽  
Respiratory Muscles ◽  
Arterial Pco2 ◽  
Co2 Rebreathing ◽  
Before And After ◽  
Inspiratory Activity ◽  
Vagal Reflex ◽  
External Oblique ◽  
Low Levels ◽  
Spontaneously Breathing

The effect of methacholine-induced bronchoconstriction on the electrical activity of respiratory muscles during expiration was studied in 12 anesthetized spontaneously breathing dogs. Before and after aerosols of methacholine, diaphragm, parasternal intercostal, internal intercostal, and external oblique electromyograms were recorded during 100% O2 breathing and CO2 rebreathing. While breathing 100% O2, five dogs showed prolonged electrical activity of the diaphragm and parasternal intercostals in early expiration, postinspiratory inspiratory activity (PIIA). Aerosols of methacholine increased pulmonary resistance, decreased tidal volume, and elevated arterial PCO2. During bronchoconstriction, when PCO2 was varied by CO2 rebreathing, PIIA was shorter at low levels of PCO2, and external oblique and internal intercostal were higher at all levels of PCO2. Vagotomy shortened PIIA in dogs with prolonged PIIA. After vagotomy, methacholine had no effects on PIIA but continued to increase external oblique and internal intercostal activity at all levels of PCO2. These findings indicate that bronchoconstriction influences PIIA through a vagal reflex but augments expiratory activity, at least in part, by extravagal mechanisms.

Mechanical function of hyoid muscles during spontaneous breathing in cats

1987 ◽  
Vol 62 (2) ◽  
pp. 582-590 ◽  
Author(s):  
E. van Lunteren ◽  
M. A. Haxhiu ◽  
N. S. Cherniack
Keyword(s):  
Electrical Activity ◽  
Mechanical Behavior ◽  
Spontaneous Breathing ◽  
High Pco2 ◽  
Primary Role ◽  
Mechanical Function ◽  
Co2 Rebreathing ◽  
Muscle Shortening ◽  
Spontaneously Breathing ◽  
The Relationship

We assessed the mechanical behavior of the geniohyoid and sternohyoid muscles during spontaneous breathing using sonomicrometry in anesthetized cats. When the animals breathed O2, the hyoid muscles either became longer or did not change length (but never shortened) during inspiration. During progressive hyperoxic hypercapnia, transient increases in geniohyoid muscle inspiratory lengthening occurred in many animals; however, at high PCO2 the geniohyoid invariably shortened during inspiration (mean 4.9% of resting length at the end of CO2 rebreathing; P less than 0.001). The PCO2 at which geniohyoid inspiratory lengthening changed to inspiratory shortening was significantly higher than the CO2 threshold for the onset of geniohyoid electrical activity (P less than 0.01). For the sternohyoid muscle, hypercapnia caused inspiratory lengthening in 13 of 17 cats and inspiratory shortening in 4 of 17 cats; on average the sternohyoid lengthened by 1.6% of resting length at the end of CO2 rebreathing (P less than 0.01). Sternohyoid lengthening occurred in spite of this muscle being electrically active. These results suggest that the relationship between hyoid muscle electrical activity and respiratory changes in length is very complex, so that the presence of hyoid muscle electrical activity does not necessarily indicate muscle shortening, and among the geniohyoid and sternohyoid muscles, the geniohyoid has a primary role as a hypopharyngeal dilator in the spontaneously breathing cat, with the sternohyoid muscle acting in an accessory capacity.

Passive shortening of canine parasternal intercostals during breathing

1989 ◽  
Vol 66 (3) ◽  
pp. 1414-1420 ◽  
Author(s):  
A. De Troyer ◽  
G. A. Farkas
Keyword(s):  
Quiet Breathing ◽  
Rib Cage ◽  
Airway Occlusion ◽  
The Third ◽  
Single Breath ◽  
Muscle Shortening ◽  
Spontaneously Breathing

We have previously demonstrated that the shortening of the canine parasternal intercostals during inspiration results primarily from the muscles' own activation (J. Appl. Physiol. 64: 1546–1553, 1988). In the present studies, we have tested the hypothesis that other inspiratory rib cage muscles may contribute to the parasternal inspiratory shortening. Eight supine, spontaneously breathing dogs were studied. Changes in length of the third or fourth right parasternal intercostal were measured during quiet breathing and during single-breath airway occlusion first with the animal intact, then after selective denervation of the muscle, and finally after bilateral phrenicotomy. Denervating the parasternal virtually eliminated the muscle shortening during quiet inspiration and caused the muscle to lengthen during occluded breaths. After phrenicotomy, however, the parasternal, while being denervated, shortened again a significant amount during both quiet inspiration and occluded breaths. These data thus confirm that a component of the parasternal inspiratory shortening is not active and results from the action of other inspiratory rib cage muscles. Additional studies in four animals demonstrated that the scalene and serratus muscles do not play any role in this phenomenon; it must therefore result from the action of intrinsic rib cage muscles.

Phasic volume-related feedback on upper airway muscle activity

1984 ◽  
Vol 56 (3) ◽  
pp. 730-736 ◽  
Author(s):  
E. van Lunteren ◽  
K. P. Strohl ◽  
D. M. Parker ◽  
E. N. Bruce ◽  
W. B. Van de Graaff ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Phrenic Nerve ◽  
Muscle Activity ◽  
Moving Average ◽  
Upper Airway ◽  
Single Breath ◽  
Early Peak ◽  
Posterior Cricoarytenoid ◽  
Upper Airway Muscles ◽  
Spontaneously Breathing

The effects of vagally mediated volume-related feedback on the activity of upper airway muscles was assessed in nine pentobarbital-anesthetized, tracheostomized, spontaneously breathing dogs. Moving average electrical activity was recorded before and during single-breath airway occlusions from the genioglossus, posterior cricoarytenoid, and alae nasi muscles and compared with simultaneously recorded tidal volume and electrical activity of the phrenic nerve (6 dogs) or diaphragm (3 dogs). The normally early peak of upper airway muscle activity during unoccluded breaths was delayed to late or end inspiration during occluded breaths. Inspiratory depression started at a lower volume above end-expiratory volume and at an earlier time after inspiratory onset for the upper airway muscles than for the phrenic nerve and the diaphragm. The amount of depression at the end of inspiratory airflow was larger for all of the upper airway muscles than for the phrenic nerve and diaphragm. Depressive effects were most prominent in the genioglossus, followed by the posterior cricoarytenoid and the alae nasi. After vagotomy, depressive effects of volume-related feedback were no longer seen. These results suggest that activity of the upper airway muscles is modulated by vagally mediated feedback, apparently to a larger extent than that of the diaphragm and phrenic nerve.

Respiratory changes in nasal muscle length

1985 ◽  
Vol 59 (2) ◽  
pp. 453-458 ◽  
Author(s):  
E. van Lunteren ◽  
M. A. Haxhiu ◽  
N. S. Cherniack
Keyword(s):  
Moving Average ◽  
Muscle Length ◽  
Vagal Afferents ◽  
Emg Activity ◽  
Mean Velocity ◽  
Single Breath ◽  
Velocity Of Shortening ◽  
Relative Delay ◽  
The Mean ◽  
Spontaneously Breathing

Respiratory changes in alae nasi muscle length were recorded using sonomicrometry in pentobarbital sodium-anesthetized tracheostomized dogs spontaneously breathing 100% O2. Piezoelectric crystals were inserted via small incisions into the alae nasi of 11 animals, and bipolar fine-wire electrodes were inserted contralaterally in nine of the same animals. The alae nasi shortened during inspiration in all animals. The mean amount of shortening was 1.33 +/- 0.22% of resting length (LR), and the mean velocity of shortening during the first 200 ms was 4.60 +/- 0.69% LR/S. The onset of alae nasi shortening preceded inspiratory flow by 77 +/- 18 ms (P less than 0.002), at which time both alae nasi shortening and the moving average of electromyographic (EMG) activity had reached approximately one-third of their peak values. In contrast, there was a relative delay in alae nasi relaxation relative to the decay of alae nasi EMG at the end of expiration. Single-breath airway occlusions at end expiration changed the normally rounded pattern of alae nasi shortening and moving average EMG to a late-inspiratory peaking pattern; both total shortening and EMG were increased by similar amounts. The onset of vagally mediated volume-related inhibition of alae nasi shortening occurred synchronously with the onset of inhibition of alae nasi EMG; both occurred at lung volumes substantially below tidal volume. These results indicate that the pattern of inspiratory shortening of this nasal dilating muscle is reflected closely in the pattern of EMG activity and that vagal afferents cause substantial inhibition of alae nasi inspiratory shortening.

Single-breath method for measurement of respiratory mechanics in anesthetized animals

1982 ◽  
Vol 52 (5) ◽  
pp. 1266-1271 ◽  
Author(s):  
W. A. Zin ◽  
L. D. Pengelly ◽  
J. Milic-Emili
Keyword(s):  
Respiratory System ◽  
Flow Resistance ◽  
Respiratory Mechanics ◽  
Respiratory Muscles ◽  
Volume Flow ◽  
Single Breath ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Spontaneously Breathing ◽  
Single Breath Method

In six spontaneously breathing anesthetized cats (pentobarbital sodium, 35 mg/kg ip) airflow, changes in lung volume and tracheal pressure were measured. The airways were occluded at end inspiration (VT). During the ensuing period of apnea (Breuer-Hering inflation reflex), the animal relaxed the respiratory muscles and the passive compliance of the respiratory system (Crs) was computed by dividing VT by the tracheal pressure. While the animal was still relaxed, the airways were reopened, and during the ensuing relaxed expiration the volume-flow relationship was linear, the slope representing the time constant of the respiratory system: tau rs = Crs . Rrs, where Rrs is the flow resistance of the passive respiratory system. From the measured values of tau rs and Crs, Rrs was computed. With this information it was also possible to quantitate the antagonistic pressure developed by the inspiratory muscles during spontaneous expiration.

Respiratory response to partial paralysis in anesthetized dogs

1984 ◽  
Vol 56 (6) ◽  
pp. 1583-1588 ◽  
Author(s):  
A. Oliven ◽  
E. C. Deal ◽  
S. G. Kelsen ◽  
N. S. Cherniack
Keyword(s):  
Motor Activity ◽  
Respiratory Muscle ◽  
Respiratory Muscles ◽  
Peak Activity ◽  
Inspiratory Time ◽  
Muscle Paralysis ◽  
Anesthetized Dogs ◽  
Spontaneously Breathing ◽  
Partial Paralysis

The ability to maintain alveolar ventilation is compromised by respiratory muscle weakness. To examine the independent role of reflexly mediated neural mechanisms to decreases in the strength of contraction of respiratory muscles, we studied the effects of partial paralysis on the level and pattern of phrenic motor activity in 22 anesthetized spontaneously breathing dogs. Graded weakness induced with succinylcholine decreased tidal volume and prolonged both inspiratory and expiratory time causing hypoventilation and hypercapnia. Phrenic peak activity as well as the rate of rise of the integrated phrenic neurogram increased. However, when studied under isocapnic conditions, increases in the severity of paralysis, as assessed from the ratio of peak diaphragm electromyogram to peak phrenic activity, produced progressive increases in inspiratory time and phrenic peak activity but did not affect its rate of rise. After vagotomy, partial paralysis induced in 11 dogs with succinylcholine also prolonged the inspiratory burst of phrenic activity, indicating that vagal reflexes were not solely responsible for the alterations in respiratory timing. Muscle paresis was also induced with gallamine or dantrolene, causing similar responses of phrenic activity and respiratory timing. Thus, at constant levels of arterial CO2 in anesthetized dogs, respiratory muscle partial paralysis results in a decrease in breathing rate without changing the rate of rise of respiratory motor activity. This is not dependent solely on vagally mediated reflexes and occurs regardless of the pharmacological agent used. These observations in the anesthetized state are qualitatively different from the response to respiratory muscle paralysis or weakness observed in awake subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Paolo Formenti ◽  
Michele Umbrello ◽  
Martin Dres ◽  
Davide Chiumello
Keyword(s):  
Mechanical Ventilation ◽  
Ultrasound Imaging ◽  
Muscle Weakness ◽  
Respiratory Muscle ◽  
Muscle Activation ◽  
Invasive Mechanical Ventilation ◽  
Respiratory Muscles ◽  
Course Of Illness ◽  
Intercostal Muscles ◽  
Predictive Parameters

Abstract Although mechanical ventilation is a lifesaving treatment, abundant evidence indicates that its prolonged use (1 week or more) promotes respiratory muscle weakness due to both contractile dysfunction and atrophy. Along with the diaphragm, the intercostal muscles are one of the most important groups of respiratory muscles. In recent years, muscular ultrasound has become a useful bedside tool for the clinician to identify patients with respiratory muscle dysfunction related to critical illness and/or invasive mechanical ventilation. Images obtained over the course of illness can document changes in muscle dimension and can be used to estimate changes in function. Recent evidence suggests the clinical usefulness of ultrasound imaging in the assessment of intercostal muscle function. In this narrative review, we summarize the current literature on ultrasound imaging of the parasternal intercostal muscles as used to assess the extent of muscle activation and muscle weakness and its potential impact during discontinuation of mechanical ventilation. In addition, we proposed a practical flowchart based on recent evidence and experience of our group that can be applied during the weaning phase. This approach integrates multiple predictive parameters of weaning success with respiratory muscle ultrasound.

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