300 



RESPIRATION 



PRACTICAL EXERCISES ON CHAPTER IV. 



i. Tracing of the Respiratory Movements in Man. Pass a tape 

 through the rings B of the stethograph shown in Fig. 134, and then 



around the neck or over 

 the shoulders, so as to sup- 

 port the instrument on 

 the chest at a convenient 

 height. Fasten tapes to 

 the hooks and tie 

 them by a slip-knot 

 'round the chest. The 

 tube E is connected 

 to a recording tambour, 

 writing on a drum. Or use 

 the belt stethograph or 

 spirograph of Fitz (p. 233), 

 fastening the elastic tube 

 round the chest with the 

 chain, and connecting it 

 with a tambour or the 

 bellows recorder shown in 



Fig. 134. Stethograph. 



Fig. 137. Compare the ex- 

 tent of the excursion when 

 the tube is adjusted at different levels over the thorax and abdomen. 



2.* Production of Apnoea and Periodic Breathing in Man. Arrange 

 for taking tracings of the respiratory movements from a fellow-student 

 as in i . Let the subj ect of the experiment recline in a perfectly easy 

 position in an armchair. Let him then breathe deeply and frequently 

 for about two minutes, so as to produce a prolonged apnoea of about 

 two minutes' duration. Whenever any desire to breathe returns, the 

 breathing is to be allowed to take its own course. It may be expected 

 at first to be of the periodic (Cheyne-Stokes) type. 



3. Tracing of the Respiratory Movements in Animals. (a) Set up 

 the arrangement shown in Fig. 135, and test whether it is air-tight. 

 Have also in readiness an induction machine and electrodes arranged 

 for an interrupted current. Anaesthetize a rabbit with chloral or 

 ether (p. 217), or a small dogf with morphine and ether, or A.C.E. 

 mixture. Insert a cannula into the trachea (p. 201), and connect it 

 with the large bottle by a tube. Connect the bottle with a recording 

 tambour adjusted to write on a drum, and regulate the amount of the 

 excursion of the lever by slackening or tightening the screw-clamp. 

 Set the drum off at slow speed, and take a tracing. 



(6) Then disconnect the cannula from its tube. Dissect out the vagus 

 in the lower part of the neck, pass a ligature under it, but dp not tie it. 

 Connect the cannula again with the bottle, and while a tracing is being 

 taken ligature the vagus. Cut below the ligature and stimulate its central 

 end with weak shocks, marking the time of stimulation on the drum. 

 Repeat the stimulation with strong shocks, and observe the results. 



* This experiment is only to be attempted under the direct supervision of 

 the demonstrator. 



f If a large dog is used the bottle should be omitted, the tracheal cannula 

 being connected with the stem of a T-tube. One end of the horizontal limb 

 of the T-tube is connected with the tambour; the other is provided with a 

 rubber tube, which can be partially closed by a screw-clamp to regulate the 

 excursion. Ether may be given when required by connecting the horizontal 

 limb of the T-tube with a bottle with two glass tubes in the cork (p. 201). 



