Dynamic respiratory mechanics in intact anesthetized hamsters

1980 ◽  
Vol 49 (2) ◽  
pp. 197-203 ◽  
Author(s):  
G. L. Strope ◽  
C. L. Cox ◽  
R. L. Pimmel ◽  
W. A. Clyde
Keyword(s):  
Tidal Volume ◽  
Respiratory Mechanics ◽  
Minute Ventilation ◽  
Dynamic Compliance ◽  
Respiratory Frequency ◽  
Small Animals ◽  
Mean Values ◽  
Expiratory Resistance ◽  
Inspiratory Resistance ◽  
Acute Changes

A system for measuring parameters of ventilation and respiratory mechanics in intact anesthetized hamsters was developed. Means ± SD of five weekly measurements in eight hamsters were 0.68 ± 0.09 ml for tidal volume, 45 ± 14 breaths.min-1 for respiratory frequency, 29.3 ± 10.4 ml.min-1 for minute ventilation, 0.301 ± 0.080 ml.cmH2O-1 for dynamic compliance, 0.435 ± 0.151 cmH2O.ml-1.s for inspiratory resistance, 0.311± 0.101 cmH2O.ml-1.s for expiratory resistance, and 0.334 ± 0.096 cmH2O.ml-1.s for average resistance. The standard deviations of five consecutive measurements of these parameters on the same day were typically 10% of the corresponding mean values suggesting that acute changes as small as 10% can be detected in a study of similar size. The corresponding value for five single measurements on different days at weekly intervals was 30%. We believe that this system yields reasonable and repeatable measurements, and, because it is atraumatic, it can be used in chronic studies of diseases in hamsters and other small animals.

Ventilatory response to hypoxia in unanesthetized newborn kittens

1988 ◽  
Vol 64 (6) ◽  
pp. 2544-2551 ◽  
Author(s):  
H. Rigatto ◽  
C. Wiebe ◽  
C. Rigatto ◽  
D. S. Lee ◽  
D. Cates
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Quiet Sleep ◽  
Newborn Kitten ◽  
Peripheral Mechanism ◽  
Flow Through ◽  
Ventilatory Response To Hypoxia

We studied the ventilatory response to hypoxia in 11 unanesthetized newborn kittens (n = 54) between 2 and 36 days of age by use of a flow-through system. During quiet sleep, with a decrease in inspired O2 fraction from 21 to 10%, minute ventilation increased from 0.828 +/- 0.029 to 1.166 +/- 0.047 l.min-1.kg-1 (P less than 0.001) and then decreased to 0.929 +/- 0.043 by 10 min of hypoxia. The late decrease in ventilation during hypoxia was related to a decrease in tidal volume (P less than 0.001). Respiratory frequency increased from 47 +/- 1 to 56 +/- 2 breaths/min, and integrated diaphragmatic activity increased from 14.9 +/- 0.9 to 20.2 +/- 1.4 arbitrary units; both remained elevated during hypoxia (P less than 0.001). Younger kittens (less than 10 days) had a greater decrease in ventilation than older kittens. These results suggest that the late decrease in ventilation during hypoxia in the newborn kitten is not central but is due to a peripheral mechanism located in the lungs or respiratory pump and affecting tidal volume primarily. We speculate that either pulmonary bronchoconstriction or mechanical uncoupling of diaphragm and chest wall may be involved.

scholarly journals Impact of cervical spinal cord contusion on the breathing pattern across the sleep-wake cycle in the rat

2019 ◽  
Vol 126 (1) ◽  
pp. 111-123 ◽  
Author(s):  
Kun-Ze Lee
Keyword(s):  
Spinal Cord ◽  
Tidal Volume ◽  
Spinal Injury ◽  
Cervical Spinal Cord ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Breathing Patterns ◽  
Cord Injury ◽  
Spinal Contusion ◽  
Cervical Spinal Injury

The present study was designed to investigate breathing patterns across the sleep-wake state following a high cervical spinal injury in rats. The breathing patterns (e.g., respiratory frequency, tidal volume, and minute ventilation), neck electromyogram, and electroencephalography of unanesthetized adult male rats were measured at the acute (i.e., 1 day), subchronic (i.e., 2 wk), and/or chronic (i.e., 6 wk) injured stages after unilateral contusion of the second cervical spinal cord. Cervical spinal cord injury caused a long-term reduction in the tidal volume but did not influence the sleep-wake cycle duration. The minute ventilation during sleep was usually lower than that during the wake period in uninjured animals due to a decrease in respiratory frequency. However, this sleep-induced reduction in respiratory frequency was not observed in contused animals at the acute injured stage. By contrast, the tidal volume was significantly lower during sleep in contused animals but not uninjured animals from the acute to the chronic injured stage. Moreover, the frequency of sigh and postsigh apnea was elevated in acutely contused animals. These results indicated that high cervical spinal contusion is associated with exacerbated sleep-induced attenuation of the tidal volume and higher occurrence of sleep apnea, which may be detrimental to respiratory functional recovery after cervical spinal cord injury. NEW & NOTEWORTHY Cervical spinal injury is usually associated with sleep-disordered breathing. The present study investigated breathing patterns across sleep-wake state following cervical spinal injury in the rat. Unilateral cervical spinal contusion significantly impacted sleep-induced alteration of breathing patterns, showing a blunted frequency response and exacerbated attenuated tidal volume and occurrence of sleep apnea. The result enables us to investigate effects of cervical spinal injury on the pathogenesis of sleep-disordered breathing and evaluate potential therapies to improve respiration.

Effects of nasal positive-pressure hyperventilation on the glottis in normal awake subjects

1995 ◽  
Vol 79 (1) ◽  
pp. 176-185 ◽  
Author(s):  
V. Jounieaux ◽  
G. Aubert ◽  
M. Dury ◽  
P. Delguste ◽  
D. O. Rodenstein
Keyword(s):  
Tidal Volume ◽  
Positive Pressure Ventilation ◽  
Anterior Commissure ◽  
Minute Ventilation ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Vocal Cords ◽  
Diaphragmatic Muscle ◽  
Inspiratory Resistance ◽  
Cyclic Changes

We have recently observed obstructive apneas during nasal intermittent positive-pressure ventilation (nIPPV) and suggested that they were due to hypocapnia-induced glottic closure. To confirm this hypothesis, we studied seven healthy subjects and submitted them to nIPPV while their glottis was continuously monitored through a fiber-optic bronchoscope. During wakefulness, we measured breath by breath the widest inspiratory angle formed by the vocal cords at the anterior commissure along with several other indexes. Mechanical ventilation was progressively increased up to 30 l/min. In the absence of diaphragmatic activity, increases in delivered minute ventilation resulted in progressive narrowing of the vocal cords, with an increase in inspiratory resistance and a progressive reduction in the percentage of the delivered tidal volume effectively reaching the lungs. Adding CO2 to the inspired gas led to partial widening of the glottis in two of three subjects. Moreover, activation of the diaphragmatic muscle was always associated with a significant inspiratory abduction of the vocal cords. Sporadically, complete adduction of the vocal cords was directly responsible for obstructive laryngeal apneas and cyclic changes in the glottic aperture resulted in waxing and waning of tidal volume. We conclude that in awake humans passive ventilation with nIPPV results in vocal cord adduction that depends partly on hypocapnia, but our results suggest that other factors may also influence glottic width.

Ventilation and CSF ions during hypocapnic HCl and HNO3 acidosis in conscious rabbits

1983 ◽  
Vol 55 (6) ◽  
pp. 1748-1757 ◽  
Author(s):  
E. E. Nattie ◽  
G. F. Birchard
Keyword(s):  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Co2 Production ◽  
Central Venous ◽  
Acid Base ◽  
Arterial Pco2 ◽  
Mean Values ◽  
Frequency Responses ◽  
Ionic Mechanisms ◽  
Conscious Rabbits

In conscious rabbits with preimplanted arterial, central venous, and cisterna magna catheters, we infused HNO3 or HCl to lower and maintain arterial PCO2, pH, and plasma HCO-3 at the same mean values in both groups over 9 h. The hypothesis was that greater entry into cerebrospinal fluid (CSF) of the strong anion NO-3 vs. Cl- would result in a greater decrease in CSF [HCO-3] in the HNO3 vs. the HCl experiment, even though the acid-base stress as measured by arterial PCO2 and plasma [HCO-3] was the same. The results did not support the hypothesis. With HCl acidosis, delta CSF [HCO-3] was equal to delta CSF [Cl-]. With HNO3 acidosis, delta CSF [HCO-3] was equal to delta CSF [NO-3] + delta CSF [Cl-], as both CSF Cl- and HCO-3 decreased with NO-3 entry into CSF. The change in CSF [HCO-3] appeared tightly linked to the PCO2 or the plasma [HCO-3], it did not depend on the type of acid used. The ionic mechanisms that determine the CSF [HCO-3] in metabolic acidosis appear able to utilize changes in the strong anions NO-3 and Cl- to bring about CSF acid-base regulation. The change in alveolar ventilation per unit CO2 production as reflected by the arterial PCO2 was the same in both groups, although the expired minute ventilation and respiratory frequency responses were diminished in the HNO3 vs. the HCl groups. In both groups with acidosis, tidal volume increased, whereas respiratory frequency decreased.

Relationship between Cr and breathing pattern in mechanically ventilated patients

1994 ◽  
Vol 77 (6) ◽  
pp. 2703-2708 ◽  
Author(s):  
H. Burnet ◽  
M. Bascou-Bussac ◽  
C. Martin ◽  
Y. Jammes
Keyword(s):  
Linear Regression ◽  
Tidal Volume ◽  
Multiple Linear Regression ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Upper Airways ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Ventilated Patients

In mechanically ventilated patients the natural gas-conditioning process of the upper airways is bypassed by the use of an endotracheal tube or a tracheostomy. We hypothesized that under these conditions the breathing pattern may greatly influence the convective respiratory heat loss (Cr). Cr values were computed from minute ventilation (VE) and inspiratory and expiratory gas temperatures, which were measured in six patients under mechanical ventilation for the management of cranial trauma. In each patient the effects of 11–20 different breathing patterns were investigated. Relationships between Cr and VE and between combined tidal volume and respiratory frequency were obtained by simple and multiple linear regression methods, respectively. Comparison of the standard errors of estimate indicated that multiple linear regression gives the best fit. Thus, Cr was highly dependent on the breathing pattern and was not related only to VE. For the same VE value, Cr was higher when VE was achieved with high tidal volume and low respiratory frequency. These data are consistent with previous studies in which thermal exchanges through the upper airways were taxed by hyperventilation of frigid air.

Effect of body posture on lung volumes

1961 ◽  
Vol 16 (1) ◽  
pp. 27-29 ◽  
Author(s):  
Francisco Moreno ◽  
Harold A. Lyons
Keyword(s):  
Tidal Volume ◽  
Prone Position ◽  
Supine Position ◽  
Total Lung Capacity ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Body Posture ◽  
Mean Values ◽  
Lung Capacity ◽  
Residual Capacity

The changes produced by body posture on total lung capacity and its subdivisions have been reported for all positions except the prone position. Twenty normal subjects, twelve males and eight females, had determinations of total lung capacity in the three body positions, sitting, supine and prone. Tidal volume, minute ventilation and O2 consumption were also measured. The changes found on assumption of the supine position from the sitting position were similar to those previously reported. For the prone position, a smaller inspiratory capacity and a larger expiratory reserve volume were found. The mean values were changed, respectively, –8% and +37%. Associated with these changes was a significant increase of the functional residual capacity by 636 ml. Ventilation did not change significantly from that found during sitting, unlike the findings associated with the supine position, in which position the tidal volume was decreased. Respiratory frequency remained the same for all positions. Submitted on April 5, 1960

Phonospirometry for noninvasive measurement of ventilation: methodology and preliminary results

2002 ◽  
Vol 93 (4) ◽  
pp. 1515-1526 ◽  
Author(s):  
Cheng-Li Que ◽  
Christof Kolmaga ◽  
Louis-Gilles Durand ◽  
Suzanne M. Kelly ◽  
Peter T. Macklem
Keyword(s):  
Airway Obstruction ◽  
Tidal Volume ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Flow Volume ◽  
Quiet Breathing ◽  
Neck Extension ◽  
Volume Relationship ◽  
Tracheal Sounds ◽  
Nose Clip

We measured tracheal flow from tracheal sounds to estimate tidal volume, minute ventilation (V˙i), respiratory frequency, mean inspiratory flow (Vt/Ti), and duty cycle (Ti/Ttot). In 11 normal subjects, 3 patients with unstable airway obstruction, and 3 stable asthmatic patients, we measured tracheal sounds and flow twice: first to derive flow-sound relationships and second to obtain flow-volume relationships from the sound signal. The flow-volume relationship was compared with pneumotach-derived volume. When subjects were seated, facing forward and with neck rotation, flexion, and standing, flow-volume relationship was within 15% of pneumotach-derived volume. Error increased with neck extension and while supine. We then measured ventilation without mouthpiece or nose clip from tracheal sounds during quiet breathing for up to 30 min. Normal results ± SD revealed tidal volume = 0.37 ± 0.065 liter, respiratory frequency = 19.3 ± 3.5 breaths/min, V˙i = 6.9 ± 1.2 l/min, Vt/Ti = 0.31 ± 0.06 l/s, and Ti/Ttot = 0.37 ± 0.04. Unstable airway obstruction had large V˙i due to increased Vt/Ti. With the exception of Ti/Ttot, variations in ventilatory parameters were closer to log normal than normal distributions and tended to be greater in patients. We conclude that phonospirometry measures ventilation reasonably accurately without mouthpiece, nose clip, or rigid postural constraints.

Sonomicrometric regional diaphragmatic shortening in awake sheep after thoracic surgery

1989 ◽  
Vol 67 (6) ◽  
pp. 2357-2368 ◽  
Author(s):  
A. Torres ◽  
W. R. Kimball ◽  
J. Qvist ◽  
K. Stanek ◽  
R. M. Kacmarek ◽  
...  
Keyword(s):  
Thoracic Surgery ◽  
Tidal Volume ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Quiet Breathing ◽  
Transdiaphragmatic Pressure ◽  
Right Thoracotomy ◽  
Before And After ◽  
End Tidal ◽  
End Tidal Co2

Through a right thoracotomy in seven sheep we chronically implanted sonomicrometry crystals and electromyographic electrodes in the costal and crural diaphragmatic regions. Awake sheep were studied during recovery for 4-6 wk, both during quiet breathing (QB) and during CO2 rebreathing. Tidal volume, respiratory frequency, and esophageal and gastric pressures were studied before and after surgery. Normalized resting length (LFRC) was significantly decreased for the costal segment on postoperative day 1 compared with postoperative day 28. Fractional costal shortening both during QB and at 10% end-tidal CO2 (ETCO2) increased significantly from postoperative days 1 to 28, whereas crural shortening did not change during QB but progressively increased at 10% ETCO2. Maximal costal shortening during electrophrenic stimulation was constant at 40% LFRC during recovery, although maximal crural shortening increased from 23 to 32% LFRC. Minute ventilation, tidal volume, and transdiaphragmatic pressure at 10% ETCO2 increased progressively after thoracotomy until postoperative day 28. Our results suggest there is profound diaphragmatic inhibition after thoracotomy and crystal implantation in sheep that requires at least 3-4 wk for stable recovery.

Effect of Continuous Positive Airway Pressure on the Ventilatory Response to CO2 in Preterm Infants

PEDIATRICS ◽  
1983 ◽  
Vol 71 (4) ◽  
pp. 634-638
Author(s):  
Manuel Durand ◽  
Ellen McCann ◽  
June P. Brady
Keyword(s):  
Tidal Volume ◽  
Preterm Infants ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Co2 Response ◽  
Expiratory Time ◽  
Ventilatory Response To Co2

The effect of continuous positive airway pressure (CPAP) on the ventilatory response to CO2 in newborn infants is unknown. The CO2 response to 4% CO2 in air was studied in nine preterm infants without lung disease before and during administration of CPAP (4 to 5 cm H2O) delivered by face mask. Minute ventilation, tidal volume, respiratory frequency, and end-tidal Pco2 were measured, and the slope and intercept of the CO2 response were calculated. Respiratory pattern and changes in oxygenation were also analyzed by measuring inspiratory and expiratory time, mean inspiratory flow, mean expiratory flow, effective respiratory timing, endtidal Po2, and transcutaneous Po2. CPAP significantly decreased minute ventilation from 278.7 to 197.6 mL/mm/kg (P < .001). Tidal volume and respiratory frequency were also significantly decreased. The slope of the CO2 response during CPAP was not significantly different from the slope before CPAP (36 v 33 mL/min/kg/mm Hg, P > .1), but the intercept was shifted to the right (P < .001). The decrease in respiratory frequency was primarily due to a prolongation of expiratory time (P < .05). In addition, transcutaneous Po2 increased during administration of CPAP (P < .001). These findings indicate that: (1) CPAP significantly decreases ventilation in preterm infants without lung disease, affecting both tidal volume and respiratory frequency; (2) CPAP does not appreciably alter the ventilatory response to CO2; (3) the changes in respiratory frequency are primarily accounted for by a prolongation of expiratory time; (4) CPAP improves oxygenation.

Effect of residence at altitude on the perception of breathlessness on return to sea level in normal subjects

1993 ◽  
Vol 84 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Rachel C. Wilson ◽  
W. L. G. Oldfield ◽  
P. W. Jones
Keyword(s):  
Oxygen Consumption ◽  
Tidal Volume ◽  
Sea Level ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Cycle Ergometer ◽  
Respiratory Frequency ◽  
Borg Scale ◽  
Oxygen Pulse ◽  
Ventilatory Equivalent

1. The effect of residence at altitude on the perception of breathlessness after return to sea level was examined in normal subjects. Breathlessness (Borg scale), minute ventilation, respiratory frequency, tidal volume, ‘oxygen pulse’ (oxygen consumption/heart rate) and the ventilatory equivalent for oxygen (minute ventilation/oxygen consumption) were measured at exercise (cycle-ergometer) during 5 months of training before 4 weeks at 4000 m and during the 6 month period after return to sea level. 2. There was no change in the subjects' pattern of breathing (respiratory frequency and tidal volume) or ‘oxygen pulse’ after the period at altitude (P = 0.0001). The ventilatory equivalent for oxygen was increased at all work rates after the period at altitude (P = 0.02). This ratio was slightly lower after 6 weeks and had returned to normal by 6 months (P = 0.4). 3. During training there was no change in breathlessness score (P = 0.6). On return to sea level, breathlessness score relative to ventilation was reduced (P = 0.0001). This was maintained for at least 6 weeks, but not as long as 6 months. 4. This study has demonstrated that, in normal subjects, the otherwise stable and reproducible relationship between breathlessness and ventilation may be disrupted for several weeks by factors other than lung disease. 5. The mechanism responsible for this is not clear, but the observations are consistent with the hypothesis that prior experience of breathlessness may condition subsequent estimates of breathlessness.

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