Part I. Measurement of Blood Pressure.

Form teams of two and take each other’s blood pressure. Enter the data in the table on the section C.

Measurement of human blood pressure is usually by the indirect method in which the blood pressure is estimated from the influence of externally applied pressure on the blood flow through a limb. Wrap the blood pressure measuring cuff (approximately 12 cm breadth) around the upper arm of the subject. Place the stethoscope head gently in the antecubital fossa over the brachial artery (identified by sensing the pulse). Can you hear any sound without inflating the cuff? By squeezing the bulb (with the side vent valve closed), which is attached to the cuff and the manometer, raise the cuff pressure to approximately 160 mmHg. Lower the cuff pressure gradually (2-4 mmHg per sec) by opening slightly the vent valve; watch the mercury level in the manometer while listening through the stethoscope. The pressure at which the sound first appears (sharp, tapping sound) is the systolic pressure. With progressive decreases of cuff pressure, the sound first becomes louder, and the thudding sounds gradually fade and become muffled. The pressure at which this muffling occurs is taken as the diastolic pressure. Usually the sound disappears a few mmHg below the point of muffling. Release the cuff pressure completely and wait for 10 seconds before making another measurement. What would be the effect of using a cuff that is too large or too small? Should one use a cuff of different size for the obese subject or for a small child?

A. Comparison of Methods of Blood Pressure Measurement. With the subject sitting, determine the blood pressure by using the auscultatory method described above. In addition, also determine the pressure at which the radial pulse begins during gradual deflation of the cuff (palpatory method). Take three readings for each method of determination, alternating one with the other. Before beginning the palpatory measurement, count the pulse for 15 seconds and record the pulse rate per minute. During each blood pressure measurement, also note the pressure at which the mercury column oscillates. Compare the systolic pressure determined by auscultation with the readings obtained by palpation and visual observation of oscillation. Explain the differences. Can you determine the diastolic pressure by palpation?

B. Effects of Body Position on Blood Pressure and Pulse Rate. Allow the subject to lie flat for 3 minutes, then make three blood pressure measurements by auscultation and take the pulse rate three times. Let the subject stand up, and take four blood pressure and pulse rate measurements in quick succession (approximately 1-minute intervals). Compare the systolic pressure, pulse pressure (= systolic pressure – diastolic pressure) and pulse rate in different positions. Explain the differences.

C. BLOOD PRESSURE MEASUREMENTS

a. COMPARISON OF METHODS

b. BODY POSITIONS

Supine 1                                                   ______/______            ______
Supine 2                                                   ______/______            ______
Supine 3                                                   ______/______            ______
Supine 4                                                   ______/______            ______

Mean (2,3,4)                                            ______/______            ______

Standing 1                                                 ______/_______         ______
Standing 2                                                 ______/_______         ______
Standing 3                                                 ______/_______         ______
Standing 4                                                 ______/_______         ______

Mean (2,3,4)                                             ______/_______         ______

C. Effects of Exercise on Blood Pressure and Pulse Rate. (One subject per table).

After measurements of blood pressure and pulse rate in the control state (quiet standing), the subject performs 30 deep knee bends in 30 seconds, with the blood pressure cuff wrapped around his upper arm but disconnected from the manometer. Immediately at the end of the exercise, connect the cuff to the manometer, and determine blood pressure and pulse rate as soon as possible. Repeat these measurements (Note the time of measurement) until the values return to control levels.

          EXERCISE (In the first column, write the time after ending of exercise; control represents standing at rest)

                                  Control                     ______/_______         ______

                                  _______   min          ______/_______         ______           

                                  _______   min          ______/_______         ______

                                  _______   min          ______/_______         ______           

                                  _______   min          ______/_______         ______

Using the control data and the first measurement obtained immediately after exercise, calculate the effects of exercise on stroke volume, cardiac output and total peripheral resistance by using the following assumptions: (a) the control cardiac index (cardiac output per unit body surface area) is 3.3 L/min/m², (b) the effect of the exercise on stroke volume is proportional to its effect on pulse pressure, and (c) the mean arterial pressure equals diastolic pressure + (pulse pressure/3).

Calculation of Cardiac Output, Stroke Volume and Total Peripheral Resistance.

                                                                                                  Control                  Exercise

      Systolic pressure (SP, mm Hg)                                              ______                  ______
      Diastolic pressure (DP, mm Hg)                                            ______                  ______
      Pulse rate (HR, per min)                                                        ______                  ______
      Body surface area (SA, M²: estimate from Ht. & Wt.)           ______                  ______

      Pulse pressure (PP = SP-DP)                                                 ______                 ______
      Control cardiac output (COc = 3.3 SA, L/min)                        ______                 
      Control stroke volume (SVc = COc /HRc ’ ml)                       ______                 
      Exercise Stroke Volume (SVe = SVc x PPe/PPc, ml)                                           ______
      Exercise Cardiac output (COe = SVe x HRe ’ L/min)                                           ______
      Mean Arterial Pressure [MAP = DP + (PP/3), mmHg]            ______                 ______
      Total peripheral resistance (TPR = MAP/CO, mmHg-sec/ml)  ______                 ______

Hemodynamic Effects of Exercise (Percent of control):

        100 HRe /HRc =                           %
        100 SVe /SVc =                           %
        100 COe /COc =                          %
        100 MAPe /MAPc =                     %
        100 TPRe/TPRc =                        %

Surface area of the human is according to the formula:

Surface Area (sq.cm.) = Wt^0.425 x Ht^0.725 x 71.84

Wt is the weight in kilograms, and Ht is the height in centimeters.  

(From DuBois and DuBois. Arch. Internal. Med. 17:865,1916)

Part II. COLD PRESSOR TEST

Record blood pressure and pulse rate from right arm at 1 min intervals until a stable reading is obtained. Continue the recording and perform the cold pressure test by placing left hand and lower forearm in basin containing equal parts of water and ice for 2 min. What is the effect of cold pressor test on blood pressure and heart rate?

                                     Blood Pressure                         Pulse Rate
                                        (sys./dias.)                                (/min)

Control                            ____________                          _______

1 min (in ice)                  ____________                          _______

2 min (in ice)                  ____________                          _______

3 min                               ____________                          _______

4 min                               ____________                          _______

5min                                ____________                          _______

Part III. Study of Skin Capillaries in Men

A. The White Reaction.   Draw a blunt instrument lightly across the skin. Observe the area for a few minutes. The response to this mild mechanical stimulus is independent of the local innervation.

B. The Red Reaction.   Draw a blunt instrument firmly across the forearm. The lighter flush of an arteriolar flare may be seen peripheral to the red reaction.

C. The Triple Response.   Draw a blunt instrument 6 to 7 times over the same area of the skin. Look for local vasodilation, the flare, and local edema.

D. Veins.   Examine the veins of the hand and then allow the hands to hang at the side. Note the size of the veins. What is the effect on the veins of opening and closing the fist several times? Raise the hand slowly from the subject’s side. At what level do the veins collapse? What is the effect on the veins of the forearm and hand of applying a blood pressure cuff to the arm inflated to a pressure of 40 mmHg for 3 to 5 minutes?

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