Chapter 40: Oxygenation

Bonnie M. Wivell, MS, RN, CNS

Structure and Function of the Heart

• Right ventricle pumps blood through the pulmonary circulation

• Left ventricle pumps blood through the systemic circulation

• The circulatory system exchanges respiratory gases, nutrients, and waste products between the blood and tissues

Myocardial Pump• Four chambers: 2 atria, 2 ventricles• Fill with blood during diastole, empty during systole• CAD and cardiomyopathy result in decreased

pumping action and decreased stroke volume• Frank-Starling’s law: the more stretch on the

ventricle muscle, the greater the contraction and the greater the stroke volume▫ Diseased heart = contractile response resulting in

insufficient stroke volume → “back up” in pulmonary → Left heart failure

▫ “back up” in circulation → Right heart failure

Myocardial Blood Flow•Blood flow is unidirectional•Diastole = AV valves (mitral and tricuspid)

open and blood flows from higher pressure atria to relaxed ventricles

•Represents S1 or the first heart sound•Systole = Semilunar (aortic and pulmonic)

valves open, and blood flows from the ventricles into the aorta and pulmonary artery

•Closer of semilunar valves represents S2•Murmur caused by regurge from diseased

valve

Coronary Artery Circulation• Supplies the myocardium with oxygen and

nutrients and removes waste• Left and right coronary arteries rise from the

aorta just above and behind the aortic valve through the coronary openings

• The left coronary artery, the most abundant blood supply, feed the left ventricle, which does most of the heart’s work

• Cardiac Function• http://www.youtube.com/watch?

v=D3ZDJgFDdk0&feature=related

Blood Flow Regulation•Cardiac Output (CO) = amount of blood

ejected form the left ventricle each minute•CO changes according to the oxygen and

metabolic needs of the body•CO = SV x HR•Stroke Volume (SV) = amount of blood

ejected from the left ventricle with each contraction

•Preload = amount of blood in the LV at the end of diastole

•Afterload = the resistance to LV ejection

Conduction System• Heart’s conduction

system generates impulses needed to pump blood

• Trace the impulse• http://

www.youtube.com/watch?v=nK0_28q6WoM&NR=1

Normal Sinus Rhythm

Respiratory System• Lungs transfer O2 from

atmosphere to aveoli• Ventilation• Perfusion• Diffusion• Respirations• http://

www.youtube.com/watch?v=hp-gCvW8PRY&feature=related

Work of Breathing• Intrapleural pressure is negative or different than the

atmosphere▫ Punctured lung – lung collapses

• Inspiration – active process stimulated by chemical receptors in aorta (O2, CO2)

• Expiration – passive process that depends on elastic recoil• Surfactant – a chemical produced in the lungs to maintain the

surface tension of the alveoli and keep them from collapsing• Decreased surfactant from disease can develop atelectasis

• Difficulty breathing – use accessory muscles (elevation of the clavicles)• Seen in COPD, causes fatigue

• Compliance – ability of the lungs to distend or to expand in response to increased intraalveolar pressure; decreased compliance increases airway resistance

Lung Volumes

Pulmonary Circulation

Respiratory Gas Exchange

•Diffusion – thickness of membrane affects the rate of diffusion

• Pulm edema, pulm infiltrates, pulm effusion•Ventilation – amount of O2 entering the lungs•Perfusion – blood flow to lungs and tissues•What influences capacity of blood to carry

oxygen?•Venous blood transports the majority of CO2

Regulation of Respiration

•Neural regulators•Cerebral Cortex•Medulla Oblongata•Chemical regulation•Chemoreceptor

Factors Affecting Oxygenation

•Decrease in Hgb (O2 carrying capacity)▫ Anemia – s/s fatigue, decreased activity

tolerance, SOB, pallor, tachycardia•Decreased inspired O2 concentration•Hypovolemia•Increase metabolic rate increases O2

demand▫ Normal in pregnancy, wound healing, and

exercise as the body is building tissue▫ Fever

Conditions Affecting Chest Wall Movement• Pregnancy – baby pushes up against diaphragm

resulting in dyspnea• Obesity• MSK abnormalities – pectus excavatum,

kyphosis, lordosis, or scoliosis• Trauma – multiple rib fractures develop into a

flail chest (unstable chest wall); incisions• Neuromuscular diseases – Myasthenia gravis,

Guillain Barre syndrome, poliomyelitis• CNS – brain or spinal cord injury, phrenic nerve

damage → diaphragm does not descend properl → reduces inspiration

• Influence of chronic disease (COPD) influences the body to produce more RBCs (polycythemia vera)

Disturbances in Cardiac Functioning• Disturbances in conduction – Dysrhythmias • Altered CO

▫ Left-sided heart failure: decreased CO, pulmonary congestion

▫ Right-sided heart failure: result of pulm disease or long term left-sided failure; increase pulm vascular resistance; congestion in systemic circulation (edema)

• Impaired valvular function – stenosis • Myocardial ischemia

▫ Angina▫ MI – females and elderly present differently

Alterations in Respiratory Function• Goal: PaCO2 between 35-45 mm Hg and PaO2

95-100 mm Hg• Hyperventilation: state of ventilation in excess of

that required to eliminate the CO2 produced by cellular metabolism; sometimes chemically induced (salicylate poisoning, amphetamines)

• Hypoventilation: alveolar ventilation is inadequate to meet the body’s O2 demand or to eliminate sufficient CO2; atelectasis

• Hypoxia: inadequate tissue oxygenation at the cellular level; cyanosis (central vs peripheral)

COPD vs Asthma• Physiology, emphysema• http://www.youtube.com/watch?

v=aktIMBQSXMo• http://www.youtube.com/watch?v=82gn_rDRpHk

Developmental Factors• Infants and toddlers: at risk for URIs which are

usually not dangerous• School-age children and adolescents: second

hand smoke exposure, may start smoking• Young and middle-age adults: multiple risk

factors such as unhealthy diet, lack of exercise, stress, OTC and RX meds not used as intended, illegal substances, and smoking

• Older adults: calcification of heart valves, SA node and costal cartilages; osteoporosis changes size and shape of thorax

Lifestyle

•Modify risk factors▫ Weight reduction▫ Smoking cessation▫ Low-cholesterol, low-Na+

diet▫ Management of HTN▫ Moderate exercise

•Substance abuse•Stress•Environmental factors

Nutrition

•Cardio-protective nutrition▫Fiber▫Whole grains▫Fresh fruit▫Vegetables▫Nuts▫Antioxidants▫Lean meats, fish, chicken▫Omega-3 fatty acids

Assessment• Nursing History

▫ Pain▫ Fatigue▫ Smoking ▫ Dyspnea/Orthopnea▫ Cough/hemoptysis▫ Wheezing▫ Environmental or

geographical exposures▫ Respiratory infections▫ Allergies▫ Health risks▫ Medications

Physical Exam

• Inspection – symmetry, breathing patterns, chest movement, barrel shape in COPD• Pink puffers/Blue bloaters

•Palpation• Thoracic excursion• Tenderness• Tactile fremitus, thrills, heaves, PMI• CMS, edema

•Percussion•Auscultation

Diagnostic Tests

•CBC•Cardiac Enzymes•Myoglobin•Serum Electrolytes•Cholesterol•Sputum (AFB, C/S,

Cytology)

•ECG•Stress test

(Exercise vs Thallium)

•Cardiac cath•PFTs•Bronchoscopy•Lung Scan•Thoracentesis

Nursing Diagnosis• Activity intolerance• Anxiety• Decreased cardiac

input• Fatigue• Impaired gas

exchange• Ineffective airway

clearance• Risk for infection

• Impaired spontaneous ventilation

• Impaired verbal communication

• Ineffective breathing pattern

• Ineffective health maintenance

• Risk for imbalanced fluid volume

Planning• Goals and outcomes

▫ Pt. will have clear lungs to auscultation▫ Pt. will achieve bilateral lung expansion▫ Pt. will have a productive cough▫ Pt. will have maintain/improve pulse ox

• Setting priorities• Collaborative care

▫ Family members▫ Colleagues▫ Other specialists▫ Pulmonary rehab

Implementation• Health Promotion

▫ Vaccinations• Healthy Lifestyle Behavior

▫ Low-fat, high-fiber diet▫ Reduce stress▫ Exercise▫ Maintain a good BMI ▫ Monitor cholesterol, triglycerides, HDL, LDL ▫ Eliminate smoking▫ Avoid pollutants/second hand smoke▫ Adequate hydration and sodium intake (especially if

on diuretics

Acute Care•Dyspnea management•Airway maintenance•Mobilization of pulmonary secretions•Hudification•Nebulization•Chest physiotherapy (CPT)

▫Postural drainage (see pages 932-933)•Suctioning

▫Oropharyngeal, nasopharyngeal, orothracheal, nasotracheal

Acute Care Continued

•Artificial airways (for decreased LOC)•Oral airway (displaces tongue)•Endotracheal and tracheal airway (high

risk for infection)•Maintenance and promotion of lung

expansion▫Positioning (turn, cough, deep breath)▫Incentive Spirometry (IS)

Procedures

•Thoracentesis▫http://www.youtube.com/watch?v=6-9W-

Y2dbpc&feature=related•Chest tube insertion

▫http://www.youtube.com/watch?v=B0wGmWn8Ubs&feature=related

•Pleur-Evac▫http://www.youtube.com/watch?v=-

I4bj0qwhM0

Chest Tubes• Pneumothorax – a collection of air in the pleural

space; loss of negative pressure in the intrapleural space• Spontaneous, or trauma• Often caused by the rupture of an air-filled sac in

the lung, called a bleb or bulla• From procedure such as insertion of central line

• Hemothorax – accumulation of blood and fluid in the pleural cavity usually as a result of trauma

• Tension pneumo – air pressure builds in the pleural space, collapsing the lung and creating a life-threatening event

Oxygen Therapy

•Goal•Purpose•Safety

Methods of Delivery

•Nasal cannula•Simple face mask•Venturi mask

•Home O2▫ Compressed▫ Liquid▫ Concentrator

Restorative and Continuing Care•Hydration•Coughing techniques•Respiratory muscle training•Breathing exercises

▫Pursed-lip breathing to blow off CO2•Diaphragmatic breathing

Evaluation