Vital Signs
Chapter 4: Vital Signs
Overview of Vital Signs (VS)
Definition: Vital signs are key indicators of a patient's physiological status.
The four classic vital signs:
Temperature
Pulse
Respirations
Blood Pressure
Additional observations in clinical assessments include:
Height and Weight
Level of consciousness and responsiveness (sensorium)
Level and type of pain (the “fifth vital sign”)
General clinical impression
Pulse oximetry
Electrocardiogram (ECG)
Obtaining Vital Signs
Frequency of measuring VS:
Baseline measurement is critical, especially for acutely ill inpatients in the ICU.
Frequency may depend on:
Patient's condition
Selected organ system issues
Specific procedures
Always monitor and record VS as necessary.
Measurement of Vital Signs
Importance of monitoring VS:
Isolated measurements offer limited information.
Determination of the normal baseline depends on several factors:
Age
Presence of chronic diseases
Treatment protocols
Recording trends:
Trend indicates changes over time and is defined as baseline + measurements over time.
Multiple-day graphs help in understanding patient’s status.
Monitoring Vital Sign Trends
Purpose of monitoring trends:
Shows changes in the patient's condition.
Facilitates comparison of VS with signs and symptoms to establish a differential diagnosis.
Helps determine if a patient is improving or deteriorating.
Components of expert assessment include:
Observation
Listening
Physical examination (touch)
Inquiry (question)
Validation
Reassessment
Analysis and trend evaluation
Height and Weight Measurements
Weight measurement must be routinely done:
Document in kilograms: (1 kg = 2.2 lb)
Follow-up should occur every 24 to 48 hours
Assess hydration status (i.e., dehydration or fluid overload) via intake/output (I&O) monitoring.
Equipment:
Scales must be age-appropriate and regularly calibrated.
Assessing Pain and Consciousness
Clinically significant factors include:
Cardiopulmonary distress
Anxiety
Pain level and type (considered the “fifth vital sign”)
Level of consciousness (Sensorium):
Oriented × 3 (to person, place, time)
Glasgow Coma Scale (GCS):
Objective evaluation based on behavioral responses in three areas:
Motor function
Verbal function
Eye-opening response
Body Temperature
Fever (Hyperthermia):
An elevation of body temperature above normal, often due to:
Normal activities (e.g., exercise)
Disease (e.g., infection)
Generally, a temperature greater than 102°F indicates infection but not all infections produce fever.
Fever increases O2 consumption and CO2 production:
consumption and production increase by 10% for each 1°C elevation in body temperature.
Patients with limited respiratory function may develop respiratory failure due to fever.
Hypothermia
Definition: Body temperature below normal.
Possible causes:
Head injury
Cold exposure
Compensatory mechanisms include:
Shivering
Peripheral vasoconstriction
Results in reduced O2 consumption and CO2 production and can lead to slow and shallow breathing.
Measuring Body Temperature
Temperature conversion between Fahrenheit and Celsius:
Fahrenheit to Celsius:
Celsius to Fahrenheit:
Pulse Measurements
Evaluation parameters include:
Rate, rhythm, and strength
Normal pulse rate for adults: 60 to 100 beats/min
Tachycardia: >100 beats/min
Bradycardia: <60 beats/min
Arrhythmia: irregular heartbeat.
Most common measurement site: Right radial artery.
Pulse Rhythm and Pattern
Relative equality of the intervals between beats can be categorized:
Regular
Regularly irregular
Irregularly irregular
Notable patterns include:
Bigeminy: normal beat followed by an irregular beat.
Trigeminy: 3-beat pattern consisting of either 2 normal beats followed by an irregular beat or vice versa.
Definitions of specific conditions include:
Pulse deficit: Difference in pulse rates.
Pulsus paradoxus: Fall of systolic BP by >10 mmHg during inspiration, often seen in conditions like asthma and cardiac tamponade.
Pulsus alternans: Alternation between strong and weak beats.
Respiratory Rate and Pattern
Respiratory rate varies by age and condition.
Assessment process consists of measuring depth and pattern concurrently while assessing radial pulse.
Definitions:
Tachypnea: Respiratory rate >20 breaths/min
Bradypnea: Respiratory rate <12 breaths/min
Blood Pressure (BP) Measurement
Definition: The force exerted against arterial walls.
Components:
Systolic: Peak force during ventricular contraction.
Diastolic: Force during ventricular relaxation.
Pulse pressure = systolic - diastolic.
Measurement Technique:
Indirect measurement using a sphygmomanometer.
Measurement method involves detecting Korotkoff sounds with a stethoscope during the closing and opening of arteries.
Hypertension and Hypotension
Hypertension:
Defined as BP >140/90 mm Hg.
Considered a risk factor for various diseases, including:
Heart disease
Vascular disease
Renal disease
Major modifiable risk factor for strokes, coronary artery disease (CAD), congestive heart failure (CHF), and peripheral vascular disease.
Causes of hypertension are often unknown.
Hypotension:
Defined as BP <90/60 mm Hg.
Symptoms: dizziness and fainting.
Possible causes include:
Left ventricular failure
Blood loss
Peripheral vasodilation
Orthostatic hypotension: Occurs due to changes in posture.
Errors in Blood Pressure Measurement
Common causes of erroneous high readings:
Using a cuff that is too narrow.
Cuff applied too tightly or loosely.
Excessive pressure in cuff during measurement.
Incomplete deflation of the cuff between measurements.
Common causes of erroneous low readings:
Using a cuff that is too wide.
Effects of the Respiratory Cycle on Blood Pressure
Systolic pressure decreases by 2 to 4 mm Hg during inspiration.
Pulsus paradoxus: If blood pressure drops by >10 mm Hg during inspiration or expiration, related conditions include:
Asthma
Cardiac tamponade
Notably, pulsus paradoxus in asthma indicates a more severe case.
Normal blood pressure is crucial for maintaining homeostasis in the body's systems.