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By: Paul Jason D. Laurico NCM 118 ❎ 🔹 ▪ Introduction Critical Care Nursing specialty dealing with human responses to life-threatening problems. Critical care units (CCUs) or intensive care units (ICUs): designed to meet the special needs of acutely and critically ill patients concept of ICU care has expanded from delivering care in a standard unit to bringing ICU care to patients wherever they might be. -American Association of Critical-Care Nurses (AACN) Progressive care units (PCUs)/ intermediate care or step-down units: provide a transition between the ICU and the general care unit or discharge. PCU patients are at risk for serious complications, but their risk is lower than that of ICU patients. Examples of patients found in PCU: those scheduled for interventional cardiac procedures (e.g., stent placement), awaiting heart transplant, receiving stable doses of vasoactive IV drugs (e.g., diltiazem [Cardizem]), or being weaned from prolonged mechanical ventilation. Critical Care Nurse has in-depth knowledge of anatomy, physiology, pathophysiology, pharmacology, and advanced assessment skills, as well as the ability to use advanced technology. perform frequent assessments to monitor trends (patterns) in the patient’s physiologic parameters (e.g., BP, ECG) =allows nurses to rapidly recognize and manage complications while aiding healing and recovery provide psychologic support to the patient and caregiver =must be able to communicate and collaborate with all members of the interdisciplinary health team (e.g., physician, dietitian, social worker, respiratory therapist, occupational therapist). Critical Care Patient: critically ill patient as one who is at high risk for actual or potential life- threatening health problems and who requires intense and vigilant nursing care. A patient is generally admitted to the ICU for one of three reasons: patient may be physiologically unstable, requiring advanced clinical judgments by nurses and a physician. patient may be at risk for serious complications and require frequent assessments and often invasive interventions patient may require intensive and complicated nursing support related to the use of IV polypharmacy (e.g., sedation, thrombolytics, drugs requiring titration [e.g., vasopressors]) and advanced technology (e.g., mechanical ventilation, intracranial pressure monitoring, continuous renal replacement therapy, hemodynamic monitoring). ▪ 🔹 🔻 ▪ 🔹 ◼ Principles Of Critical Care Nursing Principles are fundamental truths that serve as the foundations for behavior…” (Dalio) The principles covers professional competencies, scientific knowledge and empathy Eﬃciency Being eﬃcient can help provide eﬀective critical care, which may reduce the length of a patient's hospitalisation and the cost of treatment for the hospital and patient Appropriate medical intervention CCNs ensure that the care and medical interventions provided apply to patients' needs =includes administering systematic medication and maintaining the required life support systems. Professionalism refers to providing high-quality care while upholding accountability, respect and integrity includes demonstrating professional behaviour, communicating clearly and maintaining a positive environment. Safety and non-maleficence adhere to the protocols and standards of critical care that experts in the medical field set. emphasises the importance of increased safety standards in the physical care environment to reduce risks for patients and healthcare providers. Non-maleficence refers to providing quality care and avoiding intentional harm during treatment. Respect and care Showing care is about listening to patients' concerns with sensitivity and respecting their opinions. Critical care nursing aims to promote quality of life rather than just survival=achieved by helping patients gain control of their health through habits and thoughts that promote self-care. Fair allocation advocates treating everyone fairly when providing medical attention responsible for treating all patients with respect regardless of age, ethnicity, race, religious beliefs, sexual orientation or economic status fair allocation also requires you to ensure compliance, assign all medical resources and use medical equipment in a fair and just manner. 📌 🔸 Hemodynamics describes intravascular pressure, oxygenation, and blood flow occurring within the cardiovascular system Hemodynamic Monitoring Refers to measurement of pressure, flow and oxygenation of blood within the cardiovascular system Can use both invasive and noninvasive techniques to determine the hemodynamic status of the patient 🔹▪ 🔻 ▪ 🔻▪ ☑ Blood Pressure - - The arterial blood pressure is a measure of the pressure exerted by blood against the walls of the arterial system Systolic blood pressure (SBP): the peak pressure exerted against the arteries when the heart contracts Diastolic blood pressure (DBP): the residual pressure in the arterial system during ventricular relaxation (or filling) Expressed as the ratio of systolic to diastolic pressure Two main factors influencing BP: cardiac output (CO) and systemic vascular resistance (SVR) Force opposing the movement of blood Force is created primarily in small arteries and arterioles If SVR is increased and CO remains constant or increases, arterial BP will increase BP = CO × SVR Pulse pressure Diﬀerence between the SBP and DBP Normally about one third of the SBP If the BP is 120/80 mm Hg =the pulse pressure is 40 mm Hg Increased pulse pressure due to an increased SBP may occur during exercise or in individuals with atherosclerosis of the larger arteries Decreased pulse pressure may be found in heart failure or hypovolemia Mean Arterial Pressure (MAP) Refers to the average pressure within the arterial system that is felt by organs in the body Not the average of the diastolic and systolic pressures because the length of diastole exceeds that of systole at normal HRs Calculated as: MAP = (SBP + 2 DBP) ÷ 3 MAP greater than 60 mm Hg: needed to adequately perfuse and sustain the vital organs of an average person under most conditions; When the MAP falls below this number for a period of time, vital organs are underperfused and will become ischemic. Example: A person with a BP of 120/60 mm Hg has an estimated MAP of 80 mm Hg In patients with invasive BP monitoring, this value is automatically calculated and takes the patient’s HR into consideration Mixed venous oxygen saturation (SVO2) measurement of oxygen delivery and oxygen consumption I Normal SvO2 60-80%; Normal ScvO2 (from I an internal jugular or subclavian vein): > 70% 4 fundamental causes for a drop in SvO2: The cardiac output is not high enough to meet tissue oxygen needs - The Hb is too low The SaO2 is too low Oxygen consumption has increased E without an increase in oxgyen delivery - - 🔹 🔻 ▪ Pulmonary Artery Wedge Pressure Measurement of pulmonary capillary pressure, reflects left ventricular end diastolic pressure under normal conditions Central Venous Pressure (CVP) Measured in the right atrium or in the vena cava close to the heart. Is the right ventricular preload or right ventricular end diastolic pressure. Venous pressure: term that represents the average blood pressure within the venous compartment. describes the pressure in the thoracic vena cava near the right atrium (therefore CVP and right atrial pressure are essentially the same). major determinant of the filling pressure and therefore the preload of the right ventricle. increased by either an increase in venous blood volume or by a decrease in venous compliance; the latter change can be caused by contraction of the smooth muscle within the veins, which increases the venous vascular tone and decreases compliance. 🔸▪ ▪ 🔸🔸 🔘 Hemodynamic Monitoring Non Invasive Invasive Monitoring Clinical variables Arterial Line BP Central Venous Catheter Pulse Oximetry Swan Ganz Catheter Oxygen Dissociation Curve ECG Echocardiography Clinical Assessment Fastest and least invasive hemodynamicmonitor Clinical examination and monitoring of vital signs (HR, BP, RR), urine output, mental status, capillary refill time Blood Pressure Typically shows the pressures in the systemic vasculature during left ventricular systole (SBP) and diastole (DBP) shown in the format SBP/DBP Mean arterial blood pressure (MAP): used as an approximation of organ perfusion pressure Severely elevated BP, especially if acute, is associated with increased vascular resistance and may be associated with inadequate tissue perfusion (e.g., hypertensive encephalopathy or acute renal failure) Hypotension is a common feature of most shock states Pulse Oximeter non- invasive method of indirectly evaluating arterial oxygenation through measurement of peripheral saturation of hb detected by pulse oximeter percutaneous oxygen saturation amount of oxygen being carried by RBC indicates how eﬀectively a patient is breathing and how well blood is being transported to the body Oxygen Dissociation Curve Oxygen dissociation curve or O2 binding curve sigmoid curve (S shape) shows how the blood carries O2 from the alveoli and release the O2 into tissues shows relationship between PaO2 and the SaO2 Factors aﬀecting the curve pH Temperature CO2 2,3 Diphosphoglycerate (DPG) - a product of glycolysis that plays a role in liberating O2 in peripheral circulation - increase DPG= decrease aﬃnity of O2 to hb (inverse rel’n) marked to show three Shift to the Left oxygen levels: increase pH Normal level: PaO2 above3 decrease CO2 70mmHg decrease temperature Relative safe levels: decrease DPG 45mmHg-70mmHg Dangerous levels: PaO2 below 40mmHg Shift to the Right decrease pH Normal (middle) curve: increase CO2 Show 75% saturation increase temperature occurs at a PaO2 of 40 mmHg increase DPG Shift to (R): same saturation (75%) occurs at higher PaO2 Shift to (L): 75% saturation occurs a t PaO2 below 40mmHg imagine the curve as a man and his blanket in the cool wind Temperature: as it gets colder, the man holds the blanket tightly, closer towards him pH: think “basic” as alkaline; will make man hold blanket tighter DPG and CO2: imagine as gas/ wind; as the man holds the blanket and “wind” increase, blanket goes to the right 🔸📝▪ 🔻 🔸⚠ Review of anatomy and physiology: Cardiac Electrophysiology Cardiac conduction system Generates and transmits electrical impulses that stimulate contraction of the myocardium Specialized nerve tissue responsible for creating and transporting the electrical impulse, or action potential Action potential: electrical stimulation created by a sequence of ion fluxes through specialized channels in the membrane of cardiomyocytes that leads to cardiac contraction When the electrical signal of a depolarization reaches the contractile cells, they contract When the repolarization signal reaches the myocardial cells, they relax Thus, the electrical signals cause the mechanical pumping action of the heart Components Sinoatrial (SA) node (the pacemaker of the heart) initiates electrical impulses near opening of SVC depolarizes spontaneously and generates the normal rhythm of the heart (sinus rhythm) has rate of 60-100 impulses per minute has 3 branches (anterior, middle, posterior)= internodal tracts Atrioventricular (AV) node Located within the atrioventricular septum, near the opening of the coronary sinus Only pathway available for action potential to enter ventricles Causes a slight delay for electrical impulses to travel towards ventricles Has rate of 40-60 bpm Sends impulses down to AV bundle Atrioventricular bundle /Bundle of His Branches into left and rigth bundle branch Purkinje fibers Terminal branches where myocardial cells are stimulted to cause ventricular contraction Heart rate: determined by myocardial cells with fastest inherent firing SA node malfunction: AV nodes takes over as pacemaker In SA and AV node malfunction: pacemaker will be in ventricles (Purkinje fibers) Physiologic characteristics Automaticity: ability to initiate electrical impulse Excitability: ability to respond to an electrical impulse Conductivity: ability to transmit an electrical impulse from one cell to another 🔻 🟡 Electrocardiogram (ECG) Also termed an ECG or EKG (K means kardia for heart in Greek) Invented by a Dutch physician, William Einthoven in 1902 A simple non-invasive test that records the heart's electrical activity Provides information about the function of the intracardiac conducting tissue of the heart and reflects the presence of cardiac disease through its electrical properties With each heartbeat, an electrical impulse starts from the superior part of the heart to the bottom The impulse prompts the heart to contract and pumps blood Electrical events of the heart are usually recorded on the ECG as a pattern of a baseline broken by a P wave, a QRS complex, and a T wave ECG waveform The baseline (isoelectric line): straight line on the ECG It is the point of departure for the electrical activity of depolarizations and repolarizations of the cardiac cycles The P wave results from atrial depolarization The QRS complex is a result of ventricular depolarization and indicates the start of ventricular contraction The T wave results from ventricular repolarization and signals the beginning of ventricular relaxation ECG interval The P-R interval is the time from the beginning of the P wave to the start of the QRS complex The QRS interval or duration or width is the time from the beginning to the end of the QRS complex. The QT interval is the time from the beginning of the QRS complex to the end of the T wave The RR interval is the time from the peak of one R wave to that of the following R wave Electrode and Leads (Standard 12-lead ECG) The four extremity electrodes: LA - left arm RA - right arm N - neutral, on the right leg (electrical earth, or point zero, to which the electrical current is measured) F - foot, on the left leg The six chest electrodes: V1 - placed in the 4th intercostal space, right of the sternum V2 - placed in the 4th intercostal space, left of the sternum V3 - placed between V2 and V4 V4 - placed 5th intercostal space in the nipple line. Oﬃcial recommendations are to place V4 under the breast in women V5 - placed between V4 and V6 V6 - placed in the midaxillary line on the same height as V4 (horizontal line from V4, so not necessarily in the 5th intercostal space) 🟡 🔹🔹 ▪ Limb Leads Lead I: Right arm-negative, Left arm-positive Records electrical diﬀerence between the left and right arm electrodes Lead II: Right Arm-negative, Left Leg positive Records electrical diﬀerence between the left leg and right arm electrodes Lead III: Left Arm-negative, Left Leg positive Records electrical diﬀerence between the left leg and left arm electrodes 97 · Augmented Vector Leads Lead aVR Augmented Vector Right, positive electrode right shoulder Lead aVL Augmented Vector Left, positive electrode left shoulder Lead aVF Augmented Vector Foot, positive electrode on Foot Limb leads (I,II,II, aVR, aVL, aVF) detects vectors traveling in frontal plan Precordial Leads (Chest leads) Six positive electrodes on the surface of the chest over diﬀerent regions of the heart in order to record electrical activity in a plane perpendicular to the frontal plane The chest leads provide a diﬀerent view of the electrical activity within the heart The waveform recorded is diﬀerent for each lead compared to the limb leads ☑ Cardiac axis represents the sum of depolarisation vectors generated by individual cardiac myocytes. Clinically is is reflected by the ventricular axis, and interpretation relies on determining the relationship between the QRS axis and limb leads of the ECG Since the left ventricle makes up most of the heart muscle under normal circumstances, normal cardiac axis is directed downward and slightly to the left: Normal Axis = QRS axis between -30° and +90°. Abnormal axis deviation, indicating underlying pathology, is demonstrated by: Left Axis Deviation = QRS axis less than -30°. Right Axis Deviation = QRS axis greater than +90°. Extreme Axis Deviation = QRS axis between -90° and 180° (AKA “Northwest Axis”). estimate axis is to look at LEAD I and LEAD aVF.Examine the QRS complex in each lead and determine if it is Positive, Isoelectric (Equiphasic) or Negative: A positive QRS in Lead I puts the axis in roughly the same direction as lead I. A positive QRS in Lead II similarly aligns the axis with lead II. We can then combine both coloured areas and the area of overlap determines the axis. So If Lead I and II are both positive, the axis is between -30° and +90° (i.e. normal axis) Lead II can help determine pathological LAD from normal axis/physiological LAD 🔹🔹 🔻▪▪ 📝 🔹 ECG Paper/Grid provides a record of the patient’s rhythmI Also allows for measurement of complexes and intervals and for assessment of dysrhythmias Measure time and voltage Time: presented on horizontal axis Voltage: represented in vertical axis Has small boxes (thin lines) and large boxes (heavy lines) 1 big box/square = 25 small boxes/ squares 1 small box = 1 mm; 1 big box = 5mm x 5mm Horizontal (time: s, ms) 1 mm (1 small box) = 0.04s (40ms) 5mm (1 big box) = 0.2s (200ms) 5 big boxes = 0.2s x 5 =1s Vertical (Voltage: mV) 1 mm (1 small box) = 0.1 mV 10 mm (2 big boxes) = 1 mV Normal ECG contains wave, intervals, segments and one complex Wave: a positive or negative deflection from baseline that indicates a specific electrical event (P wave, Q wave, R wave, S wave, T wave, U wave) Interval: the time between two specific events (PR interval, QRS interval (or duration), QT interval, RR interval Segment: the length between two specific points on an ECG (PR segment, ST segment, TP segment) Complex: combination of multiple waves group together (QRS complex) Point: only J pointwhich is where the QRS complex ends and the ST segment begins Interpreting ECG Rhythm Strips Determine heart rate The 6 seconds method Denote a 6 second interval on the EKG strip The strip is marked by 3 or 6 second tick marks on the top or bottom of the graph paper Count the number of QRS complexes occurring within the 6 second interval, and then multiply that number by 10 Counting large squares Count the number of large squares present with one RR interval Divide 300 by the number obtained ▪ ✅ 🔹 ❌ 🔹 ▪ 🔹▪🔵 🟢 Dysrhythmias of Sinus Node Sinus Bradycardia P waves present followed by QRS Rhythm is regular Heart rate: 100bpm Etiology: Increased metabolic demands Decreased oxygen delivery Heart Failure Shock Hemorrhage Anemia Treatment Symptoms/Consequence Treat underlying cause May produce palpitation Occasional sedatives Prolonged episode may lead to decreased cardiac output Determine rhythm Sequential beating of the heart as a result of the generation of electrical impulses Measure the intervals between R waves (measure from R to R) Can be classified as: Regular pattern: Interval between the R waves is regular; If the intervals vary by less than 0.06 seconds or 1.5 small boxes Irregular pattern: Interval between the R waves is not regular; If the intervals between the R waves (from R to R) are variable by greater than 0.06 seconds or 1.5 small boxes Methods to determine regularity Caliper method Paper and Pen method Counting squares method ❌🔹 🔹❌▪▪ Analyzing P wave Are P waves present? Is P wave followed by QRS complex? Do the P waves look normal? (Duration, direction and shape) Duration: 0.06- 0.11s; 0.25mv) If P waves are absent, is there any atrial activity? Atrial Dysrhythmias Atrial Fibrillation Rapid, irregular P waves (>350/min) Chaotic baseline Etiology Rheumatic heart disease Mitral stenosis Atrial infarction CAD Hypertensive heart disease Thyrotoxicosis Symptoms/Consequence Treatment Hypotension Digitalis Palpitations Cardizem Pulse deficit Amiodarone Decreased cardiac output if rate is rapid Anticoagulant Promotes thrombus formation in atria Cardioversion Atrial Flutter “Saw-tooth” P waves (220-350 bpm) Etiology Heart failure Mitral valve disease Pulmonary embolus Symptoms/Consequence Occipital palpitations Chest pains Treatment Cardioversion Anticoagulant meds if cardioversion is unsuccessful Premature Atrial Beats Early P wave QRS may or may not be normal Rhythm is irregular Etiology Stress Ischemia Atrial enlargement Caﬀeine Nicotine Symptoms/Consequence May produce palpitation Frequent episode may decrease cardiac output Sign of chamber irritability Treatment Sedation Eliminate nicotine and caﬀeine May require no other treatment ❌ ✅ 🔹 🔹❌ 🔹▪ ▪▪ Measure the PR interval Normal: 0.12-.2s or 3-5 small squares >.20s: indicates Atrioventricular delay.20s) Electrical impulse still reaches the ventricles but slower than normal through the AV node mildest type of heart block Only becomes an issue when symptomatic Etiology Rheumatic fever Digitalis toxicity Degenerative changes of CAD Infections (lyme carditis) Decreased oxygen in AV node Symptoms/Consequence warns of impaired conduction Treatment Usually none as long as it occurs as an isolated deficit Atropine if PR >.26 sec or bradycardia Second-degree AV blocks Classified into two: Type I or Mobitz Type I or Wenckebach Less serious form of 2nd degree Electrical signal gets slower and slower until heart skips a beat Progressive lengthening of PR interval until QRS is dropped Type II or Mobitz Type II Most of electrical signal reach ventricles, some do not and heartbeat becomes irregular and slower than normal Etiology Acute MI The electrical signal from the atria to the Same as first-degree AV block ventricles is completely blocked Symptoms/Consequences To make up for this, the ventricle usually Serious dysrhythmia that may lead to decrease HR and CO starts to beat on its own Hypotension Third-degree block seriously aﬀects the Treatment heart’s ability to pump blood out to your May require temporary pacemaker body. If symptomatic (e.g., hypotension, dizziness): atropine 1mg Complete Third-degree AV block The electrical signal from the atria to the ventricles is completely blocked Atria and ventricles beat independently P wave has no relation to QRS Etiology Digitalis toxicity Infectious disease CAD, MI Symptyoms/Consequences Very low rates may cause decreased CO Fainting and chest pain Treatment Pacemaker Isoproterenol to increase heart rate Epinephrine if Isoproterenol ineﬀective 🟡✅ 🔹 💊 ▪ Measure QRS complex Height Height can be described as either SMALL or TALL: Small complexes are defined as < 5mm in the limb leads or < 10 mm in the chest leads Tall complexes imply ventricular hypertrophy (although can be due to body habitus e.g. tall slim people) Ventricular hypertrophy Seen in obese, hyperthyroid patients and pleural eﬀusion Width and Morphology: Can be described as NARROW (< 0.06 seconds) or WIDE (> 0.12 seconds) Narrow QRS complex occurs when the impulse is conducted down the bundle of His and the Purkinje fibre to the ventricles Results in well organised synchronised ventricular depolarization WIDE QRS complex Abnormal depolarization sequence Electrical impulse erroneously began in the ventricular tissue rather than coming through the bundle of His When electrical activity does not conduct through the His-Purkinje system, but instead travels from myocyte to myocyte =a longer time Ventricular Dysrhythmia Premature Ventricular beats Early wide, bizarre QRS not associated with-a P wave Rhythm is irregular Etiology Stress Acidosis Ventricular enlargement Electrolyte imbalance Myocardial infarction Digitalis Toxicity Hypoxemia Hypercapnia Symptoms/Consequences palpitations decreased cardiac output if frequent episodes sign of chamber irritability Treatment Check Mg and K levels Medications Procainamide Disopyramide Lidocaine Sodium Bicarbonate Potassium Oxygen Treat heart failure 🔹▪ 🔹 🔹 ▪ 💊 Ventricular Tachycardia No P wave before QRS QRS wide and bizaare ventricular rate >100, usually > 140-249 A life-threatening arrhythmia that may lead to cardiac arrest VT without a pulse is one of the ‘shockable’ cardiac arrest rhythms Etiology Treatment PVB striking during vulnerable period Medications hypoxemia Lidocaine Drug toxicity Procainamide Electrolyte imbalance Amiodarone Bradycardia Cardioversion Symptoms/Consequences Electrolytes decreased cardiac output hypotension loss of consciousness respiratory arrest Ventricular Fibrillation Chaotic electrical activity No recognizable QRS complex Development this rhythm will go into cardiac arrest One of the ‘shockable’ cardiac arrest rhythms Etiology Myocardial Infarction Electrocution Freshwater drowning Treatment Drug Toxicity Defibrillation Symptoms/Consequences Medications Epinephrine No cardica output Lidocaine Absent pulse or respiration Sodium Bicarbonate Cardica arrest Magnesium sulfate Ventricular Standstill Absence of any ventricular activity for more than a few seconds P waves may be present in which case complete heart block is blocking all impulses from reaching the ventricles and the backup or subsidiary pacemaker has failed, or there may be an absence of atrial and ventricular activity Etiology Myocardial Infarction Diseases of conducting system Symptoms/Consequences Treatment No cardica output CPR Absent pulse or respiration Pacemaker Cardica arrest Intracardiac Epinephrine Asystole no myocardial, electrical, or mechanical activity =no pulse and no circulation of blood and oxygen Absent Rhythm, Rate, P wave, PR interval, QRS Treatment CPR Medication Epinephrine 1mg q 3-5 mins Treatment of underlying cause (6H, 6T) 🔹 ▪ ▪ 🔸 Echocardiography Test using sound waves to produce live images of the heart. Image is called echocardiogram (special test that uses an ultrasound machine to look at the structure and function of the heart) May reveal: the size of the heart: if there is any change in the chamber size, dilation, or thickening blood clots in the heart chambers fluid in the sac around the heart problems with the aorta problems with the pumping function or relaxing function of the heart problems with the function of heart valves pressure in the heart 🔹 ☑ ▪ Types of Echocardiogram Transthoracic echocardiography: transducer will be placed on chest; transducer sends ultrasound waves through chest towards the heart A computer interprets the sound waves as they bounce back to the transducer painless and noninvasive Preparation: need to remove your clothes from the waist up and put on a gown. If the doctor is using a contrast dye or saline solution, they will inject or infuse the solution. let patient lie on back or side on a table or stretcher. technician will apply gel to the chest and move a wand across the chest to collect images. may ask patient to change position or hold your breath for a short time at specific intervals. Transesophageal Echocardiography Transducer tube is guided through the esophagus with the transducer behind the heart = better view NPO for 8 hours may inject a mild sedative to help you relax before starting will numb the throat with an anesthetic gel or spray will gently insert the tube into the mouth and guide it down the throat, taking care to avoid injury will move the tube up, down, and sideways to get clear images https://oneheartcardiology.com.au/service/transesophageal-echocardiogram/ ▪ ▪ Stress Echocardiography Uses transthoracic echocardiography but physician takes images of the heart before and after exercise or medications that increases heart rate Allows physician to test how the heart performs under stress Induce stress by: exercise on a treadmill or stationary bicycle medications, such as dobutamine adjusting a pacemaker, if patient have one Modified Bruce Protocol Metabolic Equivalent One MET: measure of energy you expend doing absolutely nothing measured by the amount of oxygen you consume per minute = 3.5 milliliters of oxygen per kg of body weight Metabolic Equivalent (MET) represents a standard amount of oxygen consumed by the body under resting conditions; defined as 3.5 mL O2/kg × min or ~1 kcal/kg × h example: if a certain activity is rated 5 METs, it means that you exert five times as much energy doing that activity as you would sitting still VO2 max:measure of the maximum amount of oxygen you can utilize during intense exercise; considered one of the best ways to measure cardiorespiratory fitness = shows how well the heart can keep up to meet the demands of certain aerobic exercises Bruce Protocol test: patients go through various stages, each of which lasts three minute; maximal exercise test (both speed and incline increase during each stage), while a healthcare professional measures how heart responds; total of seven stages, but may not make it through all stages. Test stops when: patient reach 85% of maximum heart rate Drop in systolic BP of greater than 10 mmHg from baseline Systolic BP of 250 mmHg or diastolic blood pressure higher than 115 mmHg (or both) Arrhythmias Chest pain/angina Fatigue, shortness of breath, leg cramps, and/or wheezing ▪ Karvonen Formula mathematical formula that helps determine the target heart rate zone formula involves using your maximum heart rate (MHR) minus age to come up with a target heart rate range (which is a percentage of your MHR). MHR the highest number of beats the heart can pump per minute when it's under high stress (physical or otherwise) can estimate your MHR or using the equation 220 - age Example, a 40-year-old's estimated MHR using this formula would be 220 – 40 years or 180 beats per minute (bpm) =straightforward and common method maximum heart rate: multiply age by 0.7, then subtract the result from 207 well beyond what most people reach (or should reach) during exercise, so don't rely on a heart rate monitor for this step. Example: age is 39 years old, estimate 207 - (0.7)(39) = 207 - 28 = ~180 bpm HRmax. Resting Heart Rate (RHR) = pulse at rest (the best time to get a true resting heart rate is first thing in the morning before getting out of bed) Heart Rate Reserve (HRR) diﬀerence between heart rate at rest and the heart rate at maximum eﬀort the extra intensity your heart has available for when you need it. HRR = HRMax - RHR Example, if maximum heart rate (HRmax) is 180 bpm and resting heart rate (RHR) is 63 bpm, then the heart rate reserve is 180 - 63 = 117 bpm. Determining Exercise Intensity If you're very sedentary with no exercise, you should work at about 57% to 67% of your MHR. If you engage in minimal activity, you should work at 64% to 74% of your MHR. If you exercise sporadically, you should work at 74% to 84% of your MHR. If you exercise regularly, you should work at 80% to 91% of your MHR. If you exercise a lot at high intensities, you should work at 84% to 94% of your MHR.

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