Vital Signs Bp and SpO2 Marija Buttery 2010

BLOOD PRESSURE

BLOOD PRESSURE Blood pressure is the measurement of force exerted by the blood on the walls of the blood vessels as the heart contracts and relaxes Systolic – is the pressure of the blood exerted on the walls of the vessels when the heart contracts Diastolic – is the pressure of the blood exerted on the walls of the vessels when the heart is relaxed. For example Mr Harris’ Bp is 150/80 – 150(systolic) / 80(diastolic)

BLOOD PRESSURE Blood pressure is measured in mmHg (millimetres of mercury) A rise or fall in blood pressure can cause significant problems for the entire body The pressure is what enables to blood to go from the heart around the entire body then back to the heart Where there is not enough blood pressure, parts of the body will not be supplied with enough blood, oxygen and nutrients. Where the blood pressure is too high it puts a strain on all the parts of the body.

BLOOD PRESSURE Hypertension – elevated blood pressure Hypotension – low blood pressure There is also postural hypotension where the blood pressure drops when the patient stands

Definitions and classification of BP levels (measured in mm Hg) Heart Foundation 2004 Category Systolic Diastolic Normal 90 - 120 60 - 80 High-normal 120 – 139 80 - 89 Grade 1 (mild) 140 – 159 90 - 99 Grade 2 (moderate) 160 – 179 100 - 109 Grade 3 (severe) ≥ 180 ≥ 110 www.heartfoundation.com.au “Hypertension Management Guide for Doctors 2004” p 10 accessed 23/2/06

Blood Pressure (BP) Measurement of cardiovascular function Force resulting from cardiac output and peripheral vascular resistance Indirectly measured with sphygmomanometer and stethoscope

Blood Pressure Systolic pressure/diastolic pressure BP is an easily measured vital sign that is a screening tool for identifying hypertension Hypertension is a silent disease, often without symptoms, yet can be fatal and/or cause significant morbidity

Blood Pressure Hypertension: Elevated systolic pressure only Elevated diastolic pressure only Elevated systolic and diastolic pressures Which ever value is most out of range is used to classify the degree of hypertension

Hypertension Facts (HT) High BP is major risk for heart disease and chief risk factor for: Stroke Congestive Heart Failure Myocardial infarction (MI) Can lead to kidney, liver and retinal changes

Hypertension Facts (HT) Lifestyle measures are a crucial part of treatment Lose excess weight Be physically active Limit alcoholic beverages Decrease salt intake Decrease fat intake - cholesterol Follow a heart-healthy eating plan Quit smoking

Conditions that increase BP Stress – physical or emotional Steroid therapy and other medications Hypercholesterolemia Diabetes mellitus Renal disease Hyperthyroidism

Risk Factors for HT Obesity Disease - diabetes Lack of exercise Age Obesity Disease - diabetes Lack of exercise Smoking Alcohol Stress Diet

Diagnosis of HT Made after three readings on separate days when all are elevated beyond normal If you determine a reading that is abnormal: Report to RN, may need MO review Recheck after 5 minutes Assess patient for cause (e.g. stress, just had a cigarette)

Hypotension BP < 90/60 mm Hg Orthostatic / postural hypotension Excessive fall in BP (> 20/10 mm Hg) on assuming the upright position Gravitational stress Autonomic reflex Hypovolaemia

5 Factors Determine BP Level Cardiac output Peripheral vascular resistance Total blood volume Viscosity of the blood Compliance of the arterial wall

Factors Contributing to Inaccurate BP Measurement Defective equipment Faulty technique Clinical error Failure to consider patient factors

Factors Contributing to Inaccurate BP Measurement Defective equipment Inflating system, exhaust valve & tubing without leaks Cuff fabric should be intact so pressure is distributed evenly Adjust the “0” on Hg manometers

Factors Contributing to Inaccurate BP Measurement Faulty Technique Incorrect positioning of the patient/artery Cuff size (too small or too big) Not Applying cuff evenly, snugly Placing stethoscope under the cuff

Factors Contributing to Inaccurate BP Measurement Clinician Error Same as previous Be sure to estimate systolic blood pressure Refrain from rechecking repeatedly without allowing for pressure equilibration Patient Factors Emotion, anger, anxiety, pain, frustration, sudden noises, sedation, fever

Positioning the Bp Cuff Cuff applied evenly, snugly with bottom edge about 1 inch above the antecubital fossa (elbow) Valve tubing attached to the cuff should be placed over the brachial arterial. Palpate the artery It may be difficult to hear the BP sounds in an obese patient, in the case of hypotension or if the artery is very deep in a muscular person

Measuring the BP Patient should be at rest Position the patient so that the arm is at the height of the heart Remove any clothing that may be restrictive Estimate the systolic BP

Estimating the systolic BP Palpate the radial artery (with index/middle finger) Inflate the cuff to a pressure 20 mm Hg above the point at which the radial pulsation disappears, slowly release cuff whilst feeling for return of pulse. Note the number - that is your palpable systolic pressure Deflate the cuff and wait a short time

Measuring the BP Place the diaphragm of the stethoscope over the brachial artery Close the valve of the pressure bulb Inflate the cuff to the estimated point Slowly release valve Systolic pressure is when the first sound is heard Diastolic pressure is when the sound disappears Deflate the cuff & remove

THE BRACHIAL ARTERY PULSE UNTIL THE CUFF IS INFLATED!! YOU WILL NOT HEAR THE BRACHIAL ARTERY PULSE UNTIL THE CUFF IS INFLATED!!

Systolic and Diastolic Readings Top number When the heart is contracting Diastolic Bottom number When the heart is resting (or refilling) 110 75 Marieb, E N., Essentials of Human Anatomy & Physiology 8th Ed (San Francisco: Benjamin Cummings, 2006) Fig 11.4 “Operation of the heart valves . . “ P 333 26

S for Systolic S for Squish!

Pulse Oximetry Oximeter SpO2 Sats SaO2

Pulse Oximetry A non invasive measurement of arterial blood oxygen saturation A Light Emitting Diode (LED) measures the amount of oxygen on the haemoglobin (Hb) Light waves are absorbed then reflected back by oxygenated and deoxygenated Hb molecules The light is processed by the oximeter, which calculates the pulse oxygen saturation (Sp02). It is recorded as a percentage

Inaccurate Readings Can be caused by: Movement False nails Some red/dark nail polish Direct sunlight Hypotension Peripheral vascular disease Hypothermia Oedema