The Process Of Oxygenation

JARO, KARLEEN L. BSN 3-AI THE PROCESS OF OXYGENATION − Delivery of oxygen to the body − Depends upon the interplay of pulmonary, hematologic and cardiovascular system − Processes involved are ventilation, alveolar gas exchange, oxygen transport and cellular respiration. I. − − −

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VENTILATION First step in the process of oxygenation Movement of air into and out of the lungs for the purpose of delivering fresh air in the alveoli Regulated by the respiratory centers in the pons and medulla oblongata. Rate and depth depends on the concentrating hydrogen ion and carbon dioxide (CO2) in body and fluid

Mechanics of Ventilation 1. Air Pressure Variances Air flows from region of higher pressure to a region of lower pressure. During inspiration, movement of diaphragm and other muscles of respiration enlarge the thoracic cavity and thereby lower the pressure inside the thorax to a level below that of the atmospheric pressure. During the normal expiration, the diaphragm relaxes and the lungs recoil. The alveolar pressure then exceeds atmospheric pressure, and air flows from the lungs into the atmosphere. 2. Air Way Resistance Any process that changes the bronchial diameter or widths affects airway resistance and alters the rate of airflow for a given pressure gradient during respiration. 3. Compliance It measures the (characteristics of lungs) elasticity, expandability, and distensibility of the lungs and thoracic structures. It is determined by examining the volume-pressure relationship in the lungs and the thorax. In normal compliance, the lungs and the thorax easily stretch and distend when pressure is applied. High or increased compliance occurs when the lungs have lost their elasticity and the thorax is distended. When lungs and thorax are stiff, there is low or decreased compliance.

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ALVEOLAR GAS EXCHANGE (oxygen uptake or external respiration) Once fresh air reaches the lung’s alveoli, oxygen moves from area of higher concentration (alveoli) to lower concentration (pulmonary capillary blood). The same way that CO2 diffuses from the blood to the alveolar space.

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OXYGEN TRANSPORT Once the diffusion of oxygen across the alveolar-capillary membrane occurs, the CO2 molecules are dissolved in the blood plasma. Plasma is not able to carry enough dissolved oxygen to meet the metabolic needs of the body. Oxygen carrying capacity of the blood is greatly enhanced by the presence of hemoglobin in the erythrocytes. Once oxygen is bound to hemoglobin, the oxygen is delivered to the cell of the body by circulation Hemoglobin – RBC’s major component which contains heme, a complex molecule of iron and porphyrin which gives blood its color and globin, a simple protein Hemoglobin Test – Measures the grams of hemoglobin in a 100ml of whole blood. Normal Values: Males 14.0 – 17.4 g/dL Females 12.0 – 16.0 g/dL 13.5 – 17.5 g/dL 11.5 – 15.5 g/dL Measurement of Oxygen in Blood Samples 1. Partial Pressure of Oxygen (PaO2) – measures oxygen dissolved in plasma. Normal Value: 80 – 100 mmHg 2. Oxygen Saturation (SaO2) – measures the percentage of hemoglobin saturated with oxygen. Normal Value: 95 – 100 % 96 – 98%

2nd Sem Midterm 2006-2007

OXYGENATION

Ms. Norma Mercado, RN

1

JARO, KARLEEN L. BSN 3-AI IV.

CELLULAR RESPIRATION Gas exchange at the cellular level takes place via diffusion in response to pressure gradient. Oxygen diffuses from the blood to the tissues while carbon dioxide moves from the tissues to the blood. Blood is reoxygenated.

FACTORS AFFECTING OXYGENATION 1. Age Older adults often exhibit barrel chest and require increased effort to expand the lung. They are also susceptible to respiratory infection due because of decreased activity which is an effective defense mechanism. 2. Environmental and lifestyle factors Clients who are exposed to dust, animal dander, asbestos or toxic chemicals are at an increased risk for alterations in oxygenation. Smokers as well as those exposed to it should be questioned as to the type, frequency of smoking. 3. Disease processes ASSESSMENT OF CLIENT WITH RESPIRATORY DISORDERS HEALTH HISTORY − Identify the chief reason for seeking health care − Nurse determines when the health problems started, how long it lasted, if it was relieved any time, and how relief was obtained. − Collects information about precipitating factors, duration, severity and associated factors or symptoms − Assess risk factors and genetic factors that contribute to the condition − Assess the impact of sign and symptoms on the patient’s ability to perform activities of daily living SIGNS AND SYMPTOMS Dyspnea – difficulty or labored breathing, shortness of breath to any constantly recurring irritant Cough – results from the irritation of mucous membrane anywhere in the respiratory tract. It may arise from infectious process and from airborne irritants such as smoke, dust and gas Sputum Production – reaction of lungs to any constantly recurring irritants Chest Pain – sharp, stabbing and intermittent or may be dull, aching and persistent Wheezing – high pitched musical sound heard mainly on expiration. (bronchoconstriction or airway narrowing) Clubbing Fingers – found in clients with chronic hypoxic condition, chronic lung infection and malignancies of the lungs. It is described as sponginess of the nail bed and loss of nail bed angle Hemoptysis – expectoration of blood from respiratory tract. A symptom of both pulmonary and cardiac disorder Cyanosis – bluish discoloration of the skin. It is a late sign of hypoxia (can lead to shock or death). Cyanosis appears of there is 5 g/dL of unoxygenated hemoglobin PHYSICAL ASSESSMENT OF UPPER RESPIRATORY STUCTURES 1. Nose and Sinuses − inspect the external nose for lesions, asymmetry or inflammation − examine the internal structure for swelling, color, exudates or bleeding − inspect for septum deviation, perforation or bleeding

2nd Sem Midterm 2006-2007

OXYGENATION

Ms. Norma Mercado, RN

2

JARO, KARLEEN L. BSN 3-AI −

palpate the frontal and maxillary sinuses for tenderness. Using the thumb the nurse applies gentle pressure in an upward fashion at the supraorbital ridges (frontal sinuses) and in the cheek area adjacent to the nose (maxillary). Tenderness suggests inflammation 2. Pharynx and Mouth − Instruct the client to open mouth and take deep breath − Inspect structures for color, symmetry and evidence of exudates, ulceration or enlargement 3. Trachea − Place thumb and index finger of one hand on either side of the trachea just above the sternal notch. It is normally in the midline as it enters the thoracic inlet behind the sternum. PHYSICAL ASSESSMENT OF UPPER RESPIRATORY STUCTURES 1. CHEST CONFIGURATION – normal ratio of the antero posterior diameter to lateral diameter is 1:2 Barrel Chest – increase in the antero posterior diameter of the thorax, ribs are more widely spaced and the intercostals space tend to bulge Funnel Chest – (pectus excavatum) depression of the lower portion of the sternum Pigeon Chest – results from displacement of sternum. There is an increase in the anterior diameter. Kyphoscolosis – elevation of the scapula and a corresponding S shaped spine 2. BREATHING PATTERNS AND RESPIRATORY RATE Eupnea – normal breathing 12-18 bpm Bradypnea – slower than normal <10 bpm normal depth and regular rhythm Tachypnea – rapid, shallow >24 bpm Apnea – cessation of breathing Kussmaul’s – increased rate and depth of breathing Cheyne-Stokes – regular cycle where the rate and depth of breathing increase and then decrease until apnea (usually 20 seconds) *tachypnea – stop – tachypnea – stop – tachypnea – flat line Biot’s Respiration – period of normal breathing (3-4 breaths) followed by varying period of apnea (usually 10 seconds to 1 minute) *shallow – deep – irregular

3. BREATH SOUNDS Crackles – formerly known as rales, are discrete non continuous sounds that result from delayed reopening of deflated airways. Soft high itched sound heard during inspiration Coarse Crackles – discontinuous popping sound heard in early inspiration; harsh moist sound originating in the large bronchi Fine Crackles – discontinuous popping sound heard in late inspiration; sound like hair rubbing together Sonorous Wheezes (ronchi) – deep low-pitched rumbling sound heard primarily during expiration; caused by air moving through narrowed tracheo bronchial passages Sibilant Wheezes – continuous, musical, high pitched, whistle like sounds hears during inspiration and expiration caused by air passing through narrowed or partially obstructed airways may clear without coughing.

2nd Sem Midterm 2006-2007

OXYGENATION

Ms. Norma Mercado, RN

3

JARO, KARLEEN L. BSN 3-AI Friction Rubs – harsh crackling sound, like two pieces of leather being rubbed together. Heard during inspiration alone or during both inspiration and expiration DIAGNOSTIC PROCEDURES 1. Pulmonary Function Tests − Performed to assess respiratory function and to determine the extent of dysfunction − Generally performed by a technician using spirometer that has a volume collecting device attached to a recorder. It measures lung volume, ventilatory function and the mechanics of breathing, diffusion and gas exchange. PFT results are interpreted on the basis of the degree of deviation from normal. 2. Arterial Blood Gas − ABG levels are obtained thru an arterial puncture at the radial, brachial or femoral artery. It measures arterial oxygen tension (PaO2) w/c indicates the degree of oxygenation of the blood and arterial carbon dioxide pressure (PaCO2) indicates adequacy of alveolar ventilation. It also measures the body’s ability to maintain normal pH. Normal Values: pH 7.35 – 7.45 indicates acid-base balance HCO3 22 – 26 mEq/L indicates metabolic component of acid base balance PaCO2 35 – 45 mmHg indicates adequacy of alveolar ventilation PaO2 80 – 100 mmHg represents oxygen dissolved in plasma SaO2 95 – 100% saturation of hemoglobin with oxygen 3. Pulse Oximetry − Non invasive method of continuously monitoring the oxygen saturation of hemoglobin (SaO2) − A probe or sensor is attached to the fingertip, forehead, earlobe or bridge of the nose. The sensor detects changes in oxygen saturation levels by monitoring light signals generated by the oximeter − Normal value: 95 – 100% − Values less than 85% indicates that tissues are not receiving enough oxygen 4. Capnography − End-tidal CO2 monitoring − Measures amount of CO2 expired with each breath 5. Ventilation-Perfusion Studies 6. Chest X-Ray − Normal pulmonary tissues are radioluscent − May reveal densities indicating pathologic process − Taken after full inspiration because the lungs are best visualized when aerated 7. Pulmonary Angiography − Most commonly used to identify thromboembolic disease of the lungs − It involves rapid injection of a radiopaque agent into the vascula are of the lungs for radiographic study of the pulmonary vessels 8. Cultures − throat cultures may be performed to identify organisms responsible for pharyngitis 9. Sputum Studies − Used to identify pathogenic organisms and to determine whether malignant cells are present − Expectoration is the usual method for collecting sputum specimen

2nd Sem Midterm 2006-2007

OXYGENATION

Ms. Norma Mercado, RN

4

JARO, KARLEEN L. BSN 3-AI − − −

Specimen is obtained early in the morning after they have accumulated overnight The patient is instructed to clear the nose and throat rise the mouth to decrease contamination of the sputum. After taking few deep breaths, the patient coughs rather than spits. The specimen is delivered to the laboratory within two hours.

10. Computed Tomography (CT Scan) − An imaging method in which the lungs are scanned in successive layers by narrow-beam x-ray − It can distinguish fine tissue density − May be used to define pulmonary nodules and small tumors adjacent to pleural surfaces that are not visible to routine chest x-ray 11. Magnetic Resonance Imaging − Similar to CT Scan except that magnetic fields and radio frequency signals are used instead of narrow beam xray − Yields are more detailed diagnostic image than CT Scan 12. Fluoroscopic Studies − Used to assist in invasive procedure such as chest needle biopsy or transbronchial biopsy

2nd Sem Midterm 2006-2007

OXYGENATION

Ms. Norma Mercado, RN

5