Diagnostic Tests for Oxygenation Disorders Flashcards
Diagnostic Tests for Oxygenation Disorders
- Arterial Blood Gases
- Pulse Oximetry
- Capnography and Capnometry
- Sputum Analysis
- Chest x-rays
- Pulmonary Function Tests
- Bronchoscopy
- Thoracentesis
- Lung Biopsy
Arterial Blood Gases
include: partial pressure of carbon dioxide (PaCO2), pH, bicarbonate (HCO3), and partial pressure of oxygen (PaO2), and SaO2
- blood gases are used to assess acid-base balance
- used to determine oxygenation status because PaO2 is the most accurate assessment, but pulse oximetry is an easier, non-invasive way to assess oxygenation
What do abnormal or low PaO2 levels indicate?
hypoxemia
What indicates an acid-base imbalance?
the bodys compensatory mechanism of increasing the respiratory rate in response to hypoxemia decreases PaCO2 value, impacting the acid-base balance
- higher CO2 levels indicate acidosis
- lower CO2 levels indicate alkalosis
Where is An ABG sample taken from?
directly from an artery through an arterial line or peripheral needle puncture
-usually via the radial or femoral artery, or through an indwelling arterial line or pulmonary artery catheter
ABG normal levels
- PaO2= 80 to 95 mmHg
- PaCO2= 35 to 45 mmHg
- pH= 7.35 to 7.45
- HCO3= 22 to 26 mEq/L
Pulse Oximetry
utilizes wavelengths of light to measure the saturation of hemoglobin with oxygen
- it is a noninvasive way to monitor changes in the patient’s oxygenation status
- can be used intermittently or continuously
Normal Pulse oximetry readings
between 95-99%
-below 95% may be someone with chronic respiratory distress
Nursing implications with Pulse Oximetry Readings
the nurse must confirm the accuracy of oximetry readings by evaluating the waveform and ensuring the pulse obtained through pulse oximetry correlates with the patients heart rate
- the patient experiencing carbon monoxide poisoning may have a pulse ox of 100%; but the hemoglobin is saturated with carbon dioxide not oxygen
- a person with a pulse ox of 100% with decreased hemoglobin level will still not have adequate tissue oxygenation
- place on finger, but earlobe, bridge of the nose, or the toe can be used
Capnography
continuously monitors the PaCO2 in the airway during inhalation and exhalation and provides a written tracing
Capnometry
measures the amount of CO2 exhaled without continuous tracing
Most valuable CO2 readings in capnometry device
is the end-tidal CO2 level
-measure the maximal partial pressure of CO2 obtained at the end of an exhaled breath
Abnormal capnography and capnometry values indicate what?
dysfunction of the respiratory system expelling CO2
Increase end-tidal CO2 levels may be from what?
an increase in cellular metabolism, resulting in an increased CO2 production or hyperventilation that causes an increase in the exertion of CO2 from the lungs
Disease processes that that result in increased CO2 levels are
hyperthermia, trauma, burns, and sepsis
Decrease in end-tidal CO2 levels result from what?
inadequate ventilation, respiration, or pulmonary perfusion
-conditions that cause this are slow cellular metabolism, resulting in less CO2 production; hypoventilation, resulting in a decrease excretion of CO2 from the lungs; and finally, conditions that cause an increase in alveolar dead space and shunt, which causes inadequate pulmonary capillary perfusion; this limits the diffusion of CO2 into the alveoli, that results in lower end-tidal CO2 levels
Where can Capnography devices be applied?
to the end of an artificial airway or noninvasive oxygen delivery device such as a nonrebreather mask
-device should be calibrated and zeroed
Capnometry is typically utilized for what?
endotracheal tube placement after intubation
- it is applied to the end of the endotracheal tube
- the device will show a color change to blue, indicating the presence of CO2 and intubation of the trachea
Sputum Analysis
is done to check for microorganisms and/or abnormal cell growth
- if microorganisms are indicated, then a sensitivity test is performed to determine effective antibiotic therapy
- if abnormal cells are identified, analysis to determine if the cells are malignant or non-malignant is indicated
What does a sputum analysis positive for microorganisms indicate?
indicates the presence of an infectious process such as TB or pneumonia
What does the presence of abnormal cells indicate in a sputum analysis?
a malignancy
How to collect a sputum culture for someone with a natural airway
- will be given a sterile collection device and asked to cough and deposit expectorated sputum into the container
- prior to the collection, patients should rinse the mouth to limit the contamination of normal mouth flora in the culture
- patients should be structured to collect sputum as early in the morning as possible because secretions accumulate overnight, increasing the volume of sputum collected and increasing the potential to identify microorganisms
- during the collection, the patient to be instructed to deeply inspire and expire, with the patient coughing during expiration
How to collect sputum culture with someone from a endotracheal tube or tracheostomy?
collected by suctioning the airway and placing the contents into a sterile collection device
-suctioning may cause discomfort