Airway Block Flashcards
Minute alveolar ventilation formula
(Tidal volume - Dead space) x Respiratory rate
Upper Airway Structures
Nasopharynx
Oropharynx
Laryngopharynx
Larynx
Lower Airway Structures
Trachea
Lungs
Bronchial Tree
Alveoli
Airway Openings
Nose (Nasopharynx)
Mouth (Oropharynx)
Larynx (I C ET)
In the anterior neck
Contains vocal cords
ET tube passes through vocal cords
Trachea
Air passage from larynx to lungs
Carina
Ridge that separates opening of right and left bronchus
Bronchi
Branch into secondary and tertiary bronchi and bronchioles
Alveoli
Functional units where respiratory gas exchange takes place.
* Surrounded by fine capillaries
* Surfactant prevents the alveoli from collapsing
Mediastinum
Separate the lungs; include the heart, blood vessels, trachea, esophagus, lymphatic tissue, and lymphatic vessels
Pleural Cavity
Surrounds both lungs
Primary function of lungs?
Respiration
Support Structures
Thoracic cage
Phrenic nerve
Mediastinum
Respiration
Exchange of oxygen and carbon dioxide between an organism and environment
Oxygen
Essential nutrient
Carbon Dioxide
By-product of energy production
Pulmonary Ventilation
Mechanical process of respiration
External Respiration
Transfer of O2 and CO2 between air and capillaries
Internal respiration
Transfer of O2 and CO2 between capillary cells and tissue cells
Diffusion
Gas flows from higher pressure to lower pressure
Atmospheric pressure
Pressure of gas around us (varies with altitude)
Intrapulmonic pressure
Pressure of gas in alveoli
Intrathoracic pressure
Pressure in the thoracic cavity
What happens during inspiration?
Chest wall expands
Lung space increases
Pressure gradient between intrapulmonic and atmosphere results in gas flowing into lungs
What happens during expiration?
Chest wall relaxes
Lung space decreases
Intrapulmonic pressure decreases
Pressure gradient makes gas flow out
What moves the lungs?
Diaphragm, internal, and external intercostal muscles
Factors that increase work of breathing
Loss of surfactant
Increase in airway resistance
Decrease in pulmonary compliance
Trauma or disease
Do pulmonary alveoli have a tendency to collapse?
Yes
Surfactant
Lipoproteins that reduce surface tension of pulmonary fluids
Nasal passages
Cause 50% of airway resistance during nasal breathing
Airway resistance
Decreases as bronchial tree continues to alveoli
Lung capacity
8 times a normal resting inhalation
Tidal volume
Volume inhaled or exhaled during a normal breath
Inspiratory reserve volume
Amount of gas that can be forcibly inhaled after normal inspiration
Maximum lung volume (TIER)
Combined:
* Tidal volume
* Inspiratory reserve volume
* Expiratory reserve volume
* Residual volume
Expiratory reserve volume
Amount of gas that can be forcibly exhaled after normal expiration
Inspiratory capacity (T+I)
Tidal volume + Inspiratory reserve volume
Functional residual capacity (E+R)
Expiratory reserve volume + Residual volume
Vital capacity (I+T+E)
Inspiratory reserve volume + Tidal volume + Expiratory reserve volume
Minute volume
Amount of gas inhaled/exhaled in 1 minute
Combined partial pressure (Dalton’s Law)
Total atmospheric pressure is exerted by all gases
Partial pressure is a single gas
Pulmonary circulation
Respiratory system brings oxygen from gas to blood and removes CO2
Forms of oxygen in the blood
Can be physically dissolved or chemically bound to hemoglobin
Hemoglobin
Unload CO2 and absorb O2 60x faster than plasma
* Degree of O2 combination increases when PO2 is 10-60 mmHg
* Venous blood entering lungs has PO2 of 40 mmHg and HG saturation of 75%
Carbon dioxide in the blood
Transported in plasma, blood proteins, and bicarbonate ions (primary form)
* Binds more readily to HG than O2 does
Hypoxemia
State of decreased arterial O2 content
May lead to hypoxia
Hypovolemia
Decreases total blood circulating and therefore cellular O2 levels
Respiration regulation (mechanical)
Rate, depth, and pattern of breathing
Voluntary respiration
Voluntary hyperventilation or apnea
Medullary respiratory center
Stimulates inspiratory muscles
* Inspiratory center active
* Expiratory center stimulated by inspiratory activity
Hering-Breuer reflex
Prevents overinflation of lungs via vagus nerve
Pneumotaxic center
Active only in labored breathing
Prevents overexpansion of lungs during rapid breathing
Apneustic center
Stimulates inspiratory center
-constantly active during normal respiratory rates (can be overriden by pneumotaxic center)
Chemical respiration factors
Changes in O2 and CO2
pH of fluids
* O2 is a small part
Outside respiration factors
Body temp
Drugs/medications
Pain/emotion
Sleep
Modified respirations
Cough
Sneeze
Sigh
Hiccups
Laryngeal spasm
Spasmatic closure of vocal cords
Laryngeal edema
Swelling of glottic and subglottic tissues
Fractured larynx
Motor vehicle crash common cause
Vocal cords collapse in tracheal-laryngeal opening
Cricothyrotomy may be required
Aspiration
Inhalation of non-gaseous substance into lungs
Aspiration risk factors
Diminished LOC
Iatrogenic obstructions
Mechanical disturbances of airway and GI tract
Pulsus paradoxus
Abnormal drop in systolic pressure during inspiration
Supplemental oxygen therapy
Administered only when clinically appropriate and indicated
Can help manage a wide range of conditions
Clinical goals:
* Treat hypoxia
* Decrease WOB
* Decrease myocardial work
Liquid oxygen
Converts to gas when warmed
Used when weight/space must be considered
More expensive than pressurized O2
Nasal cannula
Maximum flow rate of 6L/min
Simple face mask
O2 of 35-60% at 6-10L/min
Partial rebreathing mask
O2 of 35-60%
Allows some exhaled gas into reservoir bag
Nonrebreathing mask
O2 up to 95%
No exhaled air bag into reservoir bag
Venturi mask
O2 24-50%
Jet mixes atmospheric gases and O2
CPAP
Transmits positive pressure into airways
Can be invasive or noninvasive
Pressure of 5-7.5 cm
* Pulmonary edema
* Obstructive airway disease
Positive end-expiratory pressure (PEEP)
Maintains positive pressure at end of exhalation
Used for intubation and mechanical ventilation
Factors affecting bag-mask seal
Age over 55 years
BMI greater than 26kg/m2
Absence of teeth
Presence of beard
History of snoring
Bag-mask device
O2 from 21 to nearly 100%
Automatic transport ventilators
Plastic control module connected to 50 psi gas source
Can select tidal volumes and respiratory rates based on age
Most provide flow rate of 40L/min
* Contraindicated in patients under 5, who are awake, who have obstructed airway, or increased airway resistance
Suction devices
Fixed suction devices - powered by vacuum pumps or vacuum produced by vehicle engine manifold
Portable suction - powered by oxygen or air, electrically or manually
Suction catheter complications
Hypoxemia secondary to decreased lung volume
* May lead to cardiac rhythm disturbances and cardiac arrest
Airway stimulation may increase arterial pressure and cardiac rhythm disturbances
Coughing that may increase ICP with reduced blood flow
Increased risk of herniation in patients with head injury
Bradycardia from vagal stimulation
Soft-tissue damage to respiratory tract
Gastric tubes
Nasogastric or orogastric
Complications of decompression
Discomfort
Nausea/vomiting
Interference with mask seals or airway visualization
Nasal/esophageal/gastric trauma
Drugs used for sedation
Etomidate
Ketamine
Midazolam (Versed)
Drugs used for paralysis
Succinylcholine - depolarizing
Vecuronium, Rocuronium - non-depolarizing
Six P’s of RSI
Preparation
Preoxygenation
Pretreatment
Paralysis
Placement of tube
Postintubation management
