Welcome to Monitoring Physiological Status
Welcome to your study guide for Monitoring Physiological Status, a core topic in Unit A2 2: Body Systems and Physiological Disorders. Whether you feel completely at ease with biology or sometimes find scientific numbers a bit overwhelming, do not worry! This guide breaks down each physiological check into simple, step-by-step ideas.
In health and social care settings, taking physiological measurements (often called vital signs) is like checking the dashboard of a car. These readings show health professionals how well the body's major systems are running, alert them to sudden illnesses, and help track long-term conditions over time. For your Unit A2 2 portfolio, you will need to know how these five measurements are taken, their normal ranges, and what unusual readings tell us about an individual's health.
1. Blood Pressure (BP)
Blood pressure measures the force that circulating blood exerts against the walls of the arteries as the heart pumps it around the body.
How It Is Measured
Blood pressure is recorded using a device called a sphygmomanometer (which can be digital or manual) along with a stethoscope. The measurement is recorded in millimetres of mercury, written as mmHg.
Understanding the Two Numbers
A blood pressure reading always consists of two numbers written as a fraction (for example, 120/80mmHg):
• Systolic Pressure (Top Number): The pressure in the arteries when the heart muscle contracts (beats) and actively pushes blood out.
• Diastolic Pressure (Bottom Number): The pressure in the arteries when the heart rests and refills with blood between beats.
Memory Aid: Think S for Systolic = Squeeze (the top number when the heart pumps), and D for Diastolic = Down-time (the bottom number when the heart relaxes).
Normal Ranges and Thresholds
• Healthy Adult Range: Ideally between 90/60mmHg and 120/80mmHg.
• Hypertension (High Blood Pressure): A reading of 140/90mmHg or higher.
• Hypotension (Low Blood Pressure): A reading of 90/60mmHg or lower.
Health Significance
• Hypertension: Places extra strain on blood vessels and vital organs over time, significantly increasing the risk of a heart attack or stroke.
• Hypotension: Means the brain and body tissues may not receive enough oxygen-rich blood, leading to dizziness, fainting, or in severe cases, organ damage.
Key Takeaway: Normal blood pressure lies between 90/60mmHg and 120/80mmHg. Readings at or above 140/90mmHg signal hypertension, while readings at or below 90/60mmHg signal hypotension.
2. Peak Flow (Peak Expiratory Flow Rate - PEFR)
Peak Flow measures how fast a person can forcefully blow air out of their lungs in one quick breath. It is a direct test of how open and clear the airways are.
How It Is Measured
A person takes a deep breath in and then blows as hard and fast as possible into a handheld device called a peak flow meter.
Why There Is No Single "Normal" Number
Unlike body temperature, peak flow does not have one fixed normal value for everyone. A tall 20-year-old athlete naturally has larger lungs than an elderly, shorter individual!
To determine what is healthy for a specific person, healthcare professionals use a standardized chart called a nomogram. The expected normal reading is calculated based on three factors:
1. Age
2. Height
3. Gender
Health Significance
Peak flow is primarily used to diagnose and monitor respiratory conditions such as Asthma and Chronic Obstructive Pulmonary Disease (COPD).
• A decrease in peak flow indicates that the airways are narrowing and tightening (known as bronchoconstriction), warning the individual or practitioner that their condition is worsening and requires treatment.
Key Takeaway: Peak flow tests lung function using a meter. Expected readings depend entirely on a person's age, height, and gender found on a nomogram. Drops in peak flow indicate airway narrowing (bronchoconstriction) in conditions like asthma.
3. Body Temperature
Body temperature reflects the balance between heat produced by bodily metabolic processes and heat lost to the surrounding environment.
How It Is Measured
Body temperature is measured in degrees Celsius (°C) using medical thermometers via several different routes:
• Oral: Placed under the tongue.
• Tympanic: Placed inside the ear canal.
• Axillary: Placed in the armpit.
• Forehead: Using an infrared scanner across the skin.
Normal Ranges and Thresholds
• Healthy Adult Range: Typically 36.5°C to 37.2°C (with 37.0°C considered the standard average).
• Pyrexia (Fever): A body temperature above 38°C.
• Hypothermia: A body temperature below 35°C.
Health Significance
• Pyrexia (High Temperature): Most commonly indicates that the body's immune system is actively fighting an infection or responding to internal inflammation.
• Hypothermia (Low Temperature): Occurs when the body loses heat faster than it can produce it, usually caused by prolonged environmental exposure to cold or underlying metabolic issues.
Key Takeaway: Normal body temperature sits between 36.5°C and 37.2°C (average 37.0°C). A reading over 38°C is pyrexia (fever/infection), while a reading under 35°C is hypothermia.
4. Pulse / Heart Rate
Your pulse is the rhythmic throbbing of arteries caused by the pumping action of the heart. It tells us how many times the heart beats in a single minute.
How It Is Measured
Pulse is measured in beats per minute (bpm). It can be assessed:
• Manually: By gently pressing two fingers against an artery near the surface of the skin, most commonly the radial pulse (at the wrist) or the carotid pulse (in the neck).
• Digitally: Using an electronic monitor or a pulse oximeter clipped onto a fingertip.
Normal Ranges and Classifications
• Healthy Resting Adult Range: 60–100 bpm when fully at rest.
• Tachycardia (Fast Heart Rate): A resting heart rate above 100 bpm.
• Bradycardia (Slow Heart Rate): A resting heart rate below 60 bpm.
Note on Context: A low resting heart rate below 60 bpm is not always a sign of illness. Highly trained endurance athletes often have a resting pulse in the 40s or 50s because their heart muscle is exceptionally strong and efficient!
Health Significance
An unusually fast pulse (tachycardia) at rest can indicate stress, fever, dehydration, or cardiac arrhythmias. An abnormally low pulse (bradycardia) in a non-athlete can result in insufficient blood flow to the brain, causing lightheadedness or fatigue.
Key Takeaway: A normal resting pulse is 60–100 bpm. Over 100 bpm at rest is tachycardia; under 60 bpm at rest is bradycardia.
5. Body Mass Index (BMI)
Body Mass Index (BMI) is an internationally recognized screening calculation used to evaluate whether an adult has a healthy weight for their height.
The BMI Formula
BMI is calculated by dividing an individual's weight in kilograms by their height in metres squared:
\(\text{BMI} = \frac{\text{Weight (kg)}}{\text{Height (m)}^2}\)
Step-by-Step Calculation Example
Let us calculate the BMI of an adult who weighs 70 kg and is 1.75 m tall:
1. Step 1: Square the height: \(1.75 \times 1.75 = 3.0625\)
2. Step 2: Divide weight by height squared: \(\frac{70}{3.0625} \approx 22.86\)
3. Conclusion: Their BMI is 22.9.
Standard BMI Classifications (WHO / NHS Standard)
• Underweight: BMI less than 18.5
• Healthy Weight: BMI between 18.5 and 24.9
• Overweight: BMI between 25.0 and 29.9
• Obese: BMI of 30.0 or higher
Health Significance
• High BMI (Overweight / Obese): Significantly elevates the long-term risk of developing conditions such as Type 2 diabetes, coronary heart disease, stroke, and joint problems.
• Low BMI (Underweight): Can indicate malnutrition, eating disorders, or chronic illness, leading to weakened immunity and osteoporosis.
Key Takeaway: BMI compares weight to height using \(\text{BMI} = \frac{\text{Weight (kg)}}{\text{Height (m)}^2}\). The healthy range is 18.5 to 24.9.
Common Pitfalls to Avoid in Unit A2 2
When compiling your portfolio tasks for A2 2, examiners frequently point out the following avoidable mistakes:
1. Forgetting Units of Measurement: Always include the exact unit. Writing "120/80" or "37" will cost you marks. Always write 120/80mmHg, 37.0°C, 72 bpm, or kg/m².
2. Ignoring Context (Rest vs. Activity): Always state that pulse and blood pressure ranges apply at rest. A pulse of 115 bpm during running is completely normal physiological adaptation, but at rest, it is tachycardia.
3. Giving a Single Number for Peak Flow: Never write that a single value like "500" is normal for everyone. Explain that normal peak flow values vary based on the patient's age, height, and gender on a nomogram.
4. Lack of Critical Evaluation: In your portfolio report, explain why a specific test is relevant to a disorder. For example, regular BMI tracking is crucial for monitoring a patient with Type 2 diabetes, whereas peak flow is the primary tool for managing asthma.
Quick Revision Summary Table
Blood Pressure: Measured in mmHg using a sphygmomanometer. Normal: 90/60 to 120/80mmHg. High: \(\ge\) 140/90 (Hypertension). Low: \(\le\) 90/60 (Hypotension).
Peak Flow: Measured in L/min using a peak flow meter. Normal: Determined by age, height, and gender on a nomogram. Used for: Asthma & COPD (checks for bronchoconstriction).
Body Temperature: Measured in °C via oral, tympanic, axillary, or forehead routes. Normal: 36.5°C to 37.2°C (avg 37.0°C). High: > 38°C (Pyrexia). Low: < 35°C (Hypothermia).
Pulse / Heart Rate: Measured in bpm manually or via pulse oximeter. Normal: 60–100 bpm at rest. High: > 100 bpm (Tachycardia). Low: < 60 bpm (Bradycardia).
BMI: Calculated using \(\text{BMI} = \frac{\text{Weight (kg)}}{\text{Height (m)}^2}\). Underweight: < 18.5 | Healthy: 18.5–24.9 | Overweight: 25–29.9 | Obese: 30+.