Effects of Inspiratory Load on Chest Wall Kinematics, Breathing Pattern, and Respiratory Muscle Activity of Mouth-Breathing Children

Bipolar electromyographic (EMG) recordings were made from six chest wall and nasal sites with disk electrodes attached to the skin. Electrode locations were based on previous studies of nonspeech breathing and were designed to sample the activity of both primary and accessory respiratory muscles. EMG activity was sampled while subjects performed a series of speech and nonspeeeh tasks. The results revealed that surface electrodes could sample the activity of respiratory muscles during speech and other ventilatory tasks, particularly during the expiratory phases of the breathing cycle.

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Human Chest Wall Function while Awake and during Halothane Anesthesia

Anesthesiology ◽

10.1097/00000542-199501000-00003 ◽

1995 ◽

Vol 82 (1) ◽

pp. 6-19 ◽

Cited By ~ 49

Author(s):

David O. Warner ◽

Mark A. Warner ◽

Erik L. Ritman

Keyword(s):

Chest Wall ◽

Blood Volume ◽

Functional Residual Capacity ◽

Muscle Activity ◽

Respiratory Muscle ◽

Halothane Anesthesia ◽

Intercostal Muscles ◽

Residual Capacity ◽

Gas Volume ◽

Respiratory Muscle Activity

Background Data concerning chest wall configuration and the activities of the major respiratory muscles that determine this configuration during anesthesia in humans are limited. The aim of this study was to determine the effects of halothane anesthesia on respiratory muscle activity and chest wall shape and motion during spontaneous breathing. Methods Six human subjects were studied while awake and during 1 MAC halothane anesthesia. Respiratory muscle activity was measured using fine-wire electromyography electrodes. Chest wall configuration was determined using images of the thorax obtained by three-dimensional fast computed tomography. Tidal changes in gas volume were measured by integrating respiratory gas flow, and the functional residual capacity was measured by a nitrogen dilution technique. Results While awake, ribcage expansion was responsible for 25 +/- 4% (mean +/- SE) of the total change in thoracic volume (delta Vth) during inspiration. Phasic inspiratory activity was regularly present in the diaphragm and parasternal intercostal muscles. Halothane anesthesia (1 MAC) abolished activity in the parasternal intercostal muscles and increased phasic expiratory activity in the abdominal muscles and lateral ribcage muscles. However, halothane did not significantly change the ribcage contribution to delta Vth (18 +/- 4%). Intrathoracic blood volume, measured by comparing changes in total thoracic volume and gas volume, increased significantly during inspiration both while awake and while anesthetized (by approximately 20% of delta Vth, P < 0.05). Halothane anesthesia significantly reduced the functional residual capacity (by 258 +/- 78 ml), primarily via an inward motion of the end-expiratory position of the ribcage. Although the diaphragm consistently changed shape, with a cephalad displacement of posterior regions and a caudad displacement of anterior regions, the diaphragm did not consistently contribute to the reduction in the functional residual capacity. Halothane anesthesia consistently increased the curvature of the thoracic spine measured in the saggital plane. Conclusions The authors conclude that (1) ribcage expansion is relatively well preserved during halothane anesthesia despite the loss of parasternal intercostal muscle activity; (2) an inward displacement of the ribcage accounts for most of the decrease in functional residual capacity caused by halothane anesthesia, accompanied by changes in diaphragm shape that may be related to motion of its insertions on the thoracoabdominal wall; and (3) changes in intrathoracic blood volume constitute a significant fraction of delta Vth during tidal breathing.

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Transmission of pressure across the chest wall during the rapid thoracic compression technique in infants

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.4.1411 ◽

1994 ◽

Vol 76 (4) ◽

pp. 1411-1416 ◽

Cited By ~ 8

Author(s):

S. Stick ◽

D. Turner ◽

P. LeSouef

Keyword(s):

Chest Wall ◽

Functional Residual Capacity ◽

Muscle Activity ◽

Respiratory Muscle ◽

Pleural Space ◽

Lung Volumes ◽

Pressure Transmission ◽

Residual Capacity ◽

Static Conditions ◽

Respiratory Muscle Activity

During the rapid thoracic compression maneuver in infants, the transmission of pressure from compression jacket to pleural space and airway is less at functional residual capacity than at end inspiration. To examine whether reduced pressure transmission at functional residual capacity vs. higher lung volumes is explained by passive characteristics of the chest wall rather than by respiratory muscle activity, we assessed the pressure transmitted across the chest wall in nine anesthetized infants and young children after muscle relaxation. We measured esophageal and airway occlusion pressure during chest compressions at different lung volumes determined by varying distending pressure. In six subjects studied under static conditions, there was an approximately linear relationship between distending pressure and the proportion of pressure transmitted to the airway and esophagus from the compression jacket. The mean r2 value (95% confidence interval) was 0.80 (0.09) for pressure transmission to the airway and 0.85 (0.04) for pressure transmission to the esophagus. This relationship between lung volume and pressure transmission observed under static conditions was also demonstrated dynamically. Thus the reduced transmission of pressure from compression jacket to airway and pleural space at low lung volumes occurs independently of respiratory muscle activity.

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Human Chest Wall Function during Epidural Anesthesia

Anesthesiology ◽

10.1097/00000542-199610000-00011 ◽

1996 ◽

Vol 85 (4) ◽

pp. 761-773 ◽

Cited By ~ 53

Author(s):

David O. Warner ◽

Mark A. Warner ◽

Erik L. Ritman

Keyword(s):

Chest Wall ◽

Functional Residual Capacity ◽

Muscle Activity ◽

Respiratory Muscle ◽

Sensory Level ◽

Wall Function ◽

Rib Cage ◽

Residual Capacity ◽

The Mean ◽

Respiratory Muscle Activity

Background Although epidural anesthesia (EA) can significantly disrupt the function of the respiratory system, data concerning its effects on respiratory muscle activity and the resulting motion of the chest wall are scarce. This study aimed to determine the effects of lumbar EA on human chest wall function during quiet breathing. Methods Six persons were studied while awake and during mid-thoracic (approximately a T6 sensory level) and high (approximately a T1 sensory level) lumbar EA produced by either 2% lidocaine (two persons) or 1.5% etidocaine (four persons) with 1:200,000 epinephrine. Respiratory muscle activity was measured using fine-wire electromyography electrodes. Chest wall configuration during high EA was determined using images of the thorax obtained by three-dimensional, fast computed tomography. The functional residual capacity was measured using a nitrogen dilution technique. Results High EA abolished activity in the parasternal intercostal muscles of every participant but one, whereas the mean phasic activity of the scalene muscles was unchanged. High EA significantly decreased the inspiratory volume displacement of the rib cage compared with intact breathing but did not have a significant effect on diaphragm displacement. Therefore, high EA decreased the percentage contribution of rib cage expansion to inspiratory increases in thoracic volume (delta Vth) (from 27 +/- 2 [MSE] to 10 +/- 11% of delta Vth). Paradoxic rib cage motion during inspiration (i.e., a net inward motion during inspiration) developed in only one participant. High EA substantially increased the functional residual capacity (by 295 +/- 89 ml), with a significant net caudad motion of the end expiratory position of the diaphragm. In addition, high EA significantly decreased the volume of liquid in the thorax at end expiration in five of the six participants, a factor that also contributed to the increase in functional residual capacity in these persons. Conclusions Rib cage expansion continues to contribute to tidal volume during high EA in most subjects, even when most of the muscles of the rib cage are paralyzed; the mean phasic electrical activity of unblocked respiratory muscles such as scalenes does not increase in response to rib cage muscle paralysis produced by EA; and high EA increases the functional residual capacity, an increase produced in most participants by a caudad motion of the diaphragm and a decrease in intrathoracic blood volume.

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