Humidification Performance of Passive and Active Humidification Devices Within a Spontaneously Breathing Tracheostomized Cohort

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)

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Contraction of dog trachealis muscle in vivo: role of alpha-adrenergic receptors

Journal of Applied Physiology ◽

10.1152/jappl.1980.48.2.329 ◽

1980 ◽

Vol 48 (2) ◽

pp. 329-336 ◽

Cited By ~ 3

Author(s):

W. H. Beinfield ◽

J. Seifter

Keyword(s):

Adrenergic Receptors ◽

Beta Blockers ◽

Systemic Arterial Pressure ◽

Alpha Adrenergic Receptors ◽

Bilateral Vagotomy ◽

Cervical Trachea ◽

Spontaneously Breathing ◽

Trachealis Muscle

Contraction, relaxation, and longitudinal tension were recorded by isometric strain gauge arches attached to cervical tracheal muscle (CTM) in 60 spontaneously breathing dogs anesthetized with pentobarbital. Intravenous norepinephrine (NE) (3 X 10(-9), 6 X 10(-9), 1.2 X 10(-8), and 2.4 x 10(-8) mol/kg) increased spontaneous mechanical activities (SMA) and caused dose related contraction of CTM in all dogs even though there was no pretreatment with beta-blockers. These activities were first potentiated by propranolol and then prevented by phentolamine. NE briefly decreased SMA and induced CTM relaxation prior to the onset of contraction in one-third of dogs. Propranolol prevented this initial relaxation. CTM responses induced by NE were 1) not significantly altered by atropine, tripelennamine, bilateral vagotomy, curarization, and complete tracheal transection below transducer sites; 2) unrelated to passive constriction of cervical trachea associated with airway elongation; and 3) independent of reflexes initiated by elevations of systemic arterial pressure. The moles per kilogram doses of acetylcholine were found to exceed those of NE when their intravenous administration caused equal CTM contractions in the same dog. These findings are consistent with the existence of alpha-adrenergic receptors in CTM.

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Attenuation of Cerebral Venous Contrast in Susceptibility-Weighted Imaging of Spontaneously Breathing Pediatric Patients Sedated with Propofol

American Journal of Neuroradiology ◽

10.3174/ajnr.a1960 ◽

2010 ◽

Vol 31 (5) ◽

pp. 901-906 ◽

Cited By ~ 15

Author(s):

J. Sedlacik ◽

U. Löbel ◽

M. Kocak ◽

R.B. Loeffler ◽

J.R. Reichenbach ◽

...

Keyword(s):

Pediatric Patients ◽

Susceptibility Weighted Imaging ◽

Spontaneously Breathing

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What is the optimal anesthetic protocol for measurements of cerebral autoregulation in spontaneously breathing mice?

Experimental Brain Research ◽

10.1007/s00221-010-2447-4 ◽

2010 ◽

Vol 207 (3-4) ◽

pp. 249-258 ◽

Cited By ~ 10

Author(s):

Zhenghui Wang ◽

Beat Schuler ◽

Olga Vogel ◽

Margarete Arras ◽

Johannes Vogel

Keyword(s):

Cerebral Autoregulation ◽

Spontaneously Breathing

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