What is ventilation?
movement of air in and out of airways
What is perfusion?
getting the air that is in the alveoli to diffuse by Henry's law
ways perfusion can be prevented
blood clots, decreased blood flow, decreased blood volume
nose, paranasal sinuses, pharynx, tonsils, adenoids, larynx, trachea
lungs - pleura, mediastinum, lobes, bronchi, bronchioles, alveoli
What is shunting?
blood bypasses the alveoli without gas exchange occuring
- perfusion is better than ventilations
- low ventilation - perfusion ratio
- perfusion exceeds ventilation
causes of shunting
- mucus plug
What is dead space?
- ventilation is better than perfusion
- high ventilation - perfusion ratio
- ventilation exceeds perfusion
alveoli do not have an adequate blood supply for gas exchange to occur
causes of dead space
- pulmonary emboli
- pumonary infarction
- cardiogenic shock
What is a silent unit?
- no ventilation or perfusion
- absence of both ventilation and perfusion or with limited ventilation and perfusion
causes of a silent unit
- severe acute respiratory distress syndrome
what are some elderly considerations when discussing ventilation and perfusion?
- airways of alveoli thicken and become less compliant
- airways have more dead space
- surface area available for exchange of oxygen and carbon dioxide decreases
- alveoli begin to loose elasticity around age 50
- decrease in vital capacity occurs w/ loss of chest wall mobility --> restricts tidal flow of air
- decreased diffusion capacity for O2 w/ increasing age --> produces lower O2 levels in arterial circulation
- decreased ability to rapidly move air in and out of lungs
normal ventilation:perfusion ratio
varies in different areas of lungs
things that may alter perfusion
- change in pulmonary artery pressure
- change in alveolar pressure
- change in gravity
things that may alter ventilation
- airway blockages
- local changes in compliance
- changes in gravity
what is compliance?
measure of the force required to expand or inflate the lungs
4 possible states of gas exchange in lungs
- normal (V/Q) ratio
- shunting (low V/Q ratio)
- dead space (high V/Q ratio)
- silent unit (no ventilation or perfusion)
What is the main cause of hypoxia after thoracic or abd surgery and most types of respiratory failure?
What is the purpose of a pulse oximetry?
it's a noninvasive way to see if the pt is being oxygenated
What does the oxyhemoglobin dissociation curve show?
the relationship between the partial pressure of oxygen (PaO2) and the percentage of saturation of oxygen (SaO2)
What is PaO2?
partial pressure of alveolar oxygen
What is partial pressure?
the pressure exerted by each type of gas in a mixture of gases
What is SaO2 and what can affect it?
- percentage of saturation of oxygen
- affected by:
- carbon dioxide
- hydrogen ion concentration
What does an increase in SaO2 do to the oxyhemoglobin dissociation curve?
shifts to right
What happens when the oxyhemoglobin dissociation curve shifts to the right?
less oxygen is picked up in the lungs, but more oxygen is released to the tissues if PaO2 is unchanged
bonds are more loose
What does a decrease in SaO2 do to the oxyhemoglobin dissociation curve?
shifts to left
What happens when the oxyhemoglobin dissociation curve shifts to the left?
more oxygen is picked up in the lungs, but less oxygen is given up to the tissues if the PaO2 is unchanged
bonds between oxygen and hemoglobin become stronger
What is the normal pH of arterial blood?
What is the normal Co2 of arterial blood?
What is the normal HCO3 of arterial blood?
When a pH is below 7.35, it is said to be ___________.
When a pH is above 7.45, it is said to be ___________.
The ______ regulate the CO2 and can be corrected ________. Normally a(n) ________.
The _______ regulate the HCO3 and is ______ to fix. Normally a(n) ________.
What are the characteristics of uncomensated ABG?
- abnormal pH
- one abnormal value
- one normal value
What are the characteristics of a partially compensated ABG?
- abnormal pH
- two abnormal values
- (ALL abnormal)
What are the characteristics of a compensated ABG?
- normal pH
- 2 abnormal values
causes of normal anion gap metabolic acidosis
- *most commonly due to renal failure
- lower intestinal fistulas
- use of diurectics
- early renal insufficiency
- excessive administration of chloride
- administration of parenteral nutrition w/o bicarb or bicarb producing solutes (lactate)
causes of high anion gap metabolic acidosis
- lactic acidosis
- late phase of salicylate poisoning
- methanol or ethylene glycol toxicity
- ketoacidosis w/ starvation
signs and symptoms of metabolic acidosis
- ^ RR and depth
- peripheral vasodilation and decreased cardiac output when pH <7
- decreased BP
- cold, clammy skin
treatment for metabolic acidosis?
- directed at correcting metabolic imbalance
- decrease chloride intake if that is the problem
- administer bicarb when necessary
- monitor K+ level closely
if chronic, low Ca+ treated before chronic metabolic acidosis treated to avoid tetany from increase in pH and decrease in ionized Ca+
may receive hemodialysis or peritoneal dialysis
causes of acute metabolic alkalosis?
- *most common cause is vomiting or gastric suctioning
- pyloric stenosis (only gastric fluid is lost)
- loss of K+
- diuretic therapy that promotes excretion of K+ (thiazides, furosemide)
- excessive adrenocorticosteriod hormones (hyperaldosteronism, Cushing's syndrome)
- excessive alkali ingestion from antacids containing bicarb
- use of Na+ bicarb during CPR
causes of chronic metabolic alkalosis?
- long term diuretic therapy use
- villous adenoma
- external drainage of gastric fluids
- significant K+ depletion
- cystic fibrosis
- chronic ingestion of milk and calcium carbonate
signs and symptoms of metabolic alkalosis
- tingling of fingers and toes
- hypertonic muscles
- symptoms of hypocalcemia
- respirations are depressed as a compensatory action
- atrial tachycardia
- ventricular disturbances may occur
- frequent PVC's or U waves seen as K+ decreases
treatment of metabolic alkalosis
- aimed at correcting underlying acid-base disorder
- monitor I&O's closely (b/c of volume depletion w/GI loss)
- administer chloride so kidneys can absorb Na+ w/ Cl- (allows excretion of excess bicarb)
- restore normal fluid volume w/ NaCl solutions
- administer K+ if hypokalemic
- H2 receptor agonist to reduce production of gastric acid to reduce metabolic alkalosis associated w/ gastric suctioning (ex. Tagament)
- Carbonic anhydrase if can't tolerate rapid volume expansion (CHF)
what ALWAYS causes of respiratory acidosis?
- inadequate excretion of CO2 w/ inadequate ventilation
- causes elevation in plasma CO2 levels
causes of acute respiratory acidosis in emergency situations
- acute pulmonary edema
- aspiration of foreign object
- overdose of sedatives
- sleep apnea
- administration of oxygen to a pt w/ chronic hypercapnia (excessive CO2 in blood)
- severe pneumonia
- mechanical ventilation if rate is inadequate and CO2 is retained
what disease processes can cause respiratory acidosis?
- muscular dystrophy
- myasthenia gravis
- Guillain-Barre syndrome
causes of chronic respiratory acidosis
- pulmonary diseases
- obstructive sleep apnea
what happens if the PaCO2 does not exceed the bodies ability to compensate?
pt will be asymptomatic
why do pts w/ COPD who gradually accumulate CO2 over a prolonged period of time not develop symptoms?
compensatory renal changes have had time to occur
signs and symptoms of respiratory acidosis
- ^ pulse
- ^ B/P
- mental cloudiness
- feeling of fullness in head
- v-fib in anesthetized pt
- ^ ICP if severe
- dilated conjuctival blood vessels
treatment of respiratory acidosis
- directed at improving ventilation
- bronchodilators to reduce bronchial spasms
- antibiotics to fight infection
- thrombolytics or anti-coagulants for PE
- pulmonary hygiene measures to clear respiratory tract of mucus and purulent drainage
- adequate hydration to keep mm moist and facilitate removal of secretions
- supplemental O2 w/ caution if necessary
- mechanical ventilation if used appropriately
- semi-Fowler's position to expand chest wall
what ALWAYS causes respiratory alkalosis?
what causes hyperventilation in respiratory alkalosis?
- extreme anxiety
- early phase of salicylate intoxication
- gram-negative bacteremia
- inappropriate ventilator settings that do NOT match pt requirements
what causes chronic respiratory alkalosis?
- chronic hypocapnia
- chronic hepatic insufficiency
- cerebral tumors
signs and symptoms of respiratory alkalosis
- lightheadedness due to vasoconstriction and decreased cerebral blood flow
- inability to concentrate
- numbness and tingling
- ^ HR
- ventricular and atrial dysrhythmias
treatment of respiratory alkalosis
depends on underlying cause
if caused by anxiety, pt instructed to breath more slowly or into closed system (paper bag) to increase CO2
sedative may be needed to relieve hyperventilation
sputum studies collection
- requires doctor's order
- can be collected by nurse
- best to collect early in morning
- can instruct pt to collect specimen themselves
- should send to lab as soon as collected
2 things a pt can do that can contaminate a sputum specimen
- brush teeth
- use mouth wash
imaging studies that can be done to diagnosis respiratory illness/disease
what procedure may be done if a pt has accumulation of pleural fluid?
what is a thoracentesis?
aspiration of fluid or air from the pleural space
A thoracentesis may be preformed for ________ and/or ________ reasons.
purposes of a thoracentesis
- removal of fluid and air from pleuaral cavity
- aspiration of pleural fluids for analysis
- pleural biopsy
- instillation of meds into pleural space
what studies are ran on pleural fluid when biopsy done?
- gram stain C&S
- acid-fast staining and culture
- differential cell count
- specific gravity
- total protein
- lactic dehydrogenase
what measure can be taken when a thoracentesis is performed to lower the rate of complications?
perform under ultrasound guidance
is a thoracentesis a sterile procedure?
True or False. A nurse does not have to obtain a consent for a thoracentesis.
What is the optimal position to place a pt in for a thoracentesis?
upright, sitting on edge of bed w/ feet supported and arms on padded side table
2 other options for positioning for thoracentesis
1. straddling chair w/ arms and head resing on the back of the chair
2. lying on unaffected side w/ the HOB elevated 30-45* if unable to assume a sitting position
rationale for upright, sitting on edge of bed and leaned over table position in thoracentesis
upright position facilitates the removal of fluid that usually localizes at the base of the thorax
a position of comfort helps the pt to relax
endoscopic procedures include: __________ and _________.
what is a bronchoscopy?
the direct inspection and examination of the larynx, trachea, and bronchi through either a flexible fiberoptic bronchoscope or a rigid bronchoscope
which type of bronchoscope is used more frequently in current practice?
flexible fiberoptic bronchoscope