A-level Applied Science/Energy Transfer Systems/Physiological Status Through Monitoring

Monitoring Techniques

People who are interested in health and fitness monitor indicators of physiological status. They may do this before, during and after exercise to assess a persons current level of fitness and if their performance is changing.

In a hospital it may be necessary to monitor indicators such as blood pressure, body temperature or blood sugar level. This may be done to check a persons state of health, to check how they are recovering from an injury or operation, or to help follow the progress of a clinical condition.

You should be aware of how the following physiological indicators are measured:

• pulse rate and/or heartbeat;
• blood pressure (using a manual or an electronic digital sphygmomanometer);
• breathing rate;
• tidal volume and vital capacity of the lungs (using a simple spirometer, which can also be used to measure the rate of oxygen consumption);
• peak expiratory flow rate (using a peak flow meter).

You should know the average values for the indicators that are regarded as normal for male and female adults at rest, and be able to compare these normal values with real values. Normal values which will be used for comparison are:

Breathing:

• breathing rate 12 to15 breaths per min
• tidal volume 400 to 500 cm3
• vital capacity (male) 4.8 dm3
• vital capacity (female) 3.1 dm3
• peak flow 400 to 600 dm3 min−1

Blood pressure:

• 18-year-old male 120/80 mm Hg
• 20-year-old male 125/80 mm Hg
• 40-year-old male 135/85 mm Hg

Females usually have slightly lower blood pressure:

• 20-year-old female 123/80 mm Hg
• 40-year-old female 133/85 mm Hg

Pulse rate:

• typical range of pulse rate is 60 to 80 beats per minute

In a hospital, an electrocardiogram, spirometer and peak flow meter are used to monitor the activity of the heart and lungs. For each instrument you should be able to:

• recognise a normal trace, or the average value in the case of a peak flow meter, and describe what it shows;
• recognise traces for a normal heartbeat, sinus tachycardia, bradycardia, sinus arrhythmia and ventricular fibrillation;
• describe what such traces show about the probable physiological status of people.