Oxygen Saturation (SpO2)

• Vital signs displayed include heart rate (HR), oxygen saturation (SpO2), non-invasive blood pressure (NIPB), respiratory rate (RR), and body temperature (BT).
• Typical values shown are HR 62 BPM, SpO2 99%, NIPB 102/67 mmHg, RR 22 RPM, and BT 36.6°C.

Oxygen Saturation

• Oxygen saturation has subtypes like venous oxygen saturation (SvO2), tissue oxygen saturation (StO2), and peripheral oxygen saturation (SpO2).
• Pulse oximetry device can be used to assess oxygen saturation by way of fingertip oximeter

Definition of O2 Saturation

• Oxygen saturation represents the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (both unsaturated and saturated) in the blood.
• SpO2 = HbO2 / (HbO2 + Hb)

Normal Range of O2 Saturation

• Normal arterial blood oxygen saturation levels in humans range from 95-100%.
• Levels below 90% are considered low, or hypoxemia.

Conditions Affecting O2 Saturation

• Conditions like Chronic Obstructive Pulmonary Disease (COPD), asthma, heart disease, anemia, collapsed lung, pulmonary embolism, and congenital heart defects can impact oxygen saturation levels.

Blood Pressure Defined

• Blood pressure (BP) is the pressure or tension exerted on the arterial walls as blood pulsates through them.

Factors Affecting Blood Pressure

• Factors such as age, exercise, stress, race, genetics, food intake, obesity, smoking, alcohol consumption, and certain diseases can influence blood pressure.

Types of BP Measurement Tools

• Types of BP measurement tools include sphygmomanometers (with a calibrated glass tube containing mercury), aneroid devices (with a calibrated dial and needle), and electronic or digital devices (using a digital display and often including pulse rate).

Blood Pressure Cuff Sizes

• Blood pressure cuff size, you need to know arm circumference.
  • 22-26 cm (8.7-10.2 in) arm circumference: 12 x 22 cm cuff (small adult)
  • 27-34 cm (10.6-13.4 in) arm circumference: 16 x 30 cm cuff (adult)
  • 35-44 cm (13.8-17.3 in) arm circumference: 16 x 36 cm cuff (large adult)
  • 45-52 cm (17.7-20.5 in) arm circumference: 16 x 42 cm cuff (extra-large adult)

Pre-Procedure Steps

• Patients should rest for five minutes before blood pressure measurement.
• Measurements are typically taken with the patient seated (if ambulant), and either arm can be used.
• The patient's arm should be comfortably supported at about heart level.

Procedure Tips

• The arm should be exposed for BP readings.
• Check the cuff to ensure there is no air trapping
• Place the manometer at heart level
• Wrap cuff 2.5 cm above the antecubital area

Taking Measurements

• Ensure manometer is positioned straight & at eye level when taking measurements.
• Patient should sit in straight back chair, with arm resting on table
• Center of the cuff should be at heart level and patient should have feet flat on the floor.
• Palpate the radial pulse as the cuff is pumped. Pump until no pulse is felt to estimate preliminary systolic pressure.
• Completely deflate the cuff before proceeding.

Auscultation with Stethoscope

• The stethoscope's earpieces and diaphragm must be cleaned before use and ensure sounds are clear, not muffled.
• Parts of a stethoscope include eartips, binaural, binaural spring, tubing, bell, and diaphragm.
• Place the diaphragm over the brachial pulse.
• Inflate the cuff 20-30 mmHg above the previous preliminary systolic reading, and slowly deflate it while listening for systolic and diastolic sounds.

Systolic vs. Diastolic Reading

• The highest normal blood pressure reading is considered to be 120/80.

Korotkoff Sounds

• The phases of Korotkoff sounds that are heard when taking blood pressure:
  • Phase 1: A sharp "thud" sound is heard
  • Phase 2: A blowing or swishing sound
  • Phase 3: A softer thud sound (softer than phase 1)
  • Phase 4: A softer blowing sound that disappears
  • Phase 5: Silence

Blood Pressure & Artery States

• No sounds are heard when the artery is closed
• Sounds can be heard as artery is opening and closing
• No sounds can be heard when artery is open

Factors Affecting Blood Pressure Readings

• Some factors can decrease blood pressure readings:

  • Cuff is too small 10-40 (mmHg)
  • Cuff over clothing 10-40 (mmHg)
  • Back/feet unsupported 5-15 (mmHg)
  • Legs crossed 5-8 (mmHg)
  • Not resting 3-5 minutes 10-20 (mmHg)
  • Patient talking 10-15 (mmHg)
  • Labored breathing 5-8 (mmHg)
  • Full bladder 10-15 (mmHg)
  • Pain 10-30 (mmHg)
  • Arm above heart level 1.8/inch (mmHg)

• Some factors can increase blood pressure readings:

  • Arm below heart level 1.8/inch (mmHg)

Post-Procedure

• The blood pressure reading should be documented.

Hypertension Guidelines Comparison

• Comparison of Hypertension Definitions; Normal and Hypertensive BP Ranges; and BP Targets for Treatment:

• Guidelines for 2017 ACC/AHA:

  • Hypertension Definition: ≥ 130/80
  • Normal BP Ranges: Normal: < 120/80; Elevated: 120-129/<80
  • Hypertensive BP Ranges: Hypertension Stage 1: 130-139/80-89; Hypertension Stage 2: ≥ 140/90
  • BP Targets for Treatment:18 – 64 years (mmHg) : < 130/80; 65-79 years (mmHg): < 130/80; ≥ 80 years (mmHg) : < 130/80

• Guidelines for 2023 ESH:

  • Hypertension Definition: ≥ 140/90
  • Normal BP Ranges: Optimal: < 120/80; Normal: 120-129/80-84; High-Normal: 130-139/85-89
  • Hypertensive BP Ranges: Hypertension Grade 1: 140-159/90-99; Hypertension Grade 2: 160-179/100-109; Hypertension Grade 3: ≥ 180/110
  • BP Targets for Treatment:18 – 64 years (mmHg) : < 130/80; 65-79 years (mmHg): < 140/80*; ≥ 80 years (mmHg) : 140-150/<80

Hypotension

• Hypotension is defined as blood pressure consistently below the normal range.
• Blood pressure of <90/60 mmHg is considered hypotension.
• May be caused by loss of blood; loss of vascular tone; or cardiac pumping problem