Respiratory Motor Disturbances. 451 



In some affections the respiratory movements arc accelerated 

 and more or less superficial. Increased frequence of respiration 

 is met particularly in febrile affections and inflammatory affec- 

 tions involving tlie bronchioles. The causes underlying rapid and at 

 the same time superficial breathing are not understood; it is sup- 

 posed that the responsible influences are related with the in- 

 creased internal temperature or some irritation of the sensory 

 vagus filaments. Respiratory disturbances may also be brought 

 about bv cerebral lesions. Affections of the nervous substance 

 of the brain which do not induce paralysis of the medulla oblon- 

 gata, accumulation of fluid, parasites, haemorrhages or toxic and 

 infectious irritants, may cause an increase of intra-cerebral pres- 

 sure, this apparently disturbing the stimulation of the respiratory 

 centre, respiration becoming slowed even though the air is not 

 in anv way obstructed in its passage to the alveoli. 



When the inspired air contains poisonous gases, it is to be 

 expected that according to the character of these substances and 

 their quantitative admixture in the atmosphere there will be man- 

 ifested either violent coughing or suffocative symptoms (ammonia 

 for example) ; and inflammatory local disturbances will be induced 

 (inhalation of formol vapor) ; or that some blood change (as in 

 carbon monoxide poisoning) will be brought about by limitation 

 of the atmospheric oxygen and alteration of the haemoglobin. 



The respiratory variations are the result of regulative pro- 

 cesses set into activity automatically and reflexly by the respira- 

 torv centre. Deeper or accelerated respiratory movements may, 

 to a greater or less degree, compensate for faults of gaseous in- 

 terchange of the blood and the tissues. \Mth cessation of the fault, 

 as by removal of an obstruction to the entrance of air to the lungs, 

 and coincidently with the moment when the medulla oblongata 

 again receives a proper amount of oxygenated blood, the special 

 stimulation of the centre ends and the respiratory movements again 

 become normal. Where the causes, however, continue operative 

 and become more marked, and even the excited respiratory move- 

 ments finally become incapable of relieving the air hunger of the 

 tissues, asphyxia (siiffocatiou) must ensue. As long as the brain 

 retains its normal irritability the labored and deep respiratory 

 efforts indicate medullary irritation, and in the latter case the 

 rate of cardiac action is also slowed from the marked irritation 

 of the vagus, and the cutaneous vessels are dilated because of 

 irritation of the vasomotor center (Krehl); after a time tonic- 



