mechanical ventilation Flashcards
(30 cards)
what is mechanical ventilation?
- a machine that generates a controlled flow of gas into a pts airway
- O2 and air are generated from cylinders or wall outlets
- the gas is blended according to prescribed “inspried oxygen tension”- FiO2
- its accumulated in a receptacle in the machine, then delivered to pt via one of many available modes
indications for ventilation
-ventilatory failure
-inability to protect airway
-failure to clear the airway
(ARB, allergic reactions, etc.)
airway accesses
-Noninvasive ventilation
-nasal cannula, face mask, non-rebreather mask,
BiPAP
-Laryngeal Mack airway (LMA)
-endotrachial tube
-tracheostomy (for prolonged intubation)
types of ventilators
- negative pressure ventilators
- positive pressure ventilators
- non-invasive ventilation
negative- pressure ventilation
-creates negative pressure externally to draw the chest outward and air into the lungs
-mimics spontaneous breathing
-used for individuals with neuromuscular disorders
“iron lung”
Positive pressure ventilation
- Pushes air into lungs
- can be invasive or non-invasive
- amount of air delivered in: volume (milliliters), specific pressure
- used for individuals with acute respiratory failure
BIPAP
noninvasive positive pressure ventilator
- provides ventilator support, but uses a tight fitting mask
- used to avoid intubation
- supportive for patients with: sleep apnea, impending respiratory failure
- success varies and is limited to pt tolerance
Positive pressure ventilators
- normal respiratory properties will be reflected in your mechanical ventilation settings
- mode (spontaneous vs. mechanical)
- depth (tidal volume)
- oxygen (FiO2)
- rate
controlled mechanical ventilation (CMV)
- mode of positive-pressure ventilation
- breaths are delivered regulatory and independent of the pts own ventilatory efforts
- used when pt has no drive to breathe (-under anesthesia, chemically paralyzed)
- very rarely used
assist-controlled mechanical ventilation (ACV)
-mode of positive-pressure ventilation
-vent breath is triggered by pt inspiration
-used: to initiate mechanical ventilation
those at risk for respiratory arrest
-if the pt does not initiate a breath in a preset time the vent fires a breath at the preset vent rate
allows pt to breath faster but not slower
synchronous intermittent mandatory ventilation (SIMV)
mode of positive pressure ventilation
- allows pt to breath spontaneously without vent assistance between delivered vent breaths
- -vent has preset rate and tidal volume and will not fire when the pt produces their own breath
- coordinated with the pts own respiratory effort
SIMV commonly used
- to support ventilation
- to exercise the respiratory muscles between vent-assisted breaths
- during weaning process
Respiratory rate - SIMV rate =
spontaneous breaths
Tidal volume (VT)
- the volume of air delivered during each ventilator-augmented breath
- normal adult VT is 6-10 mL/kg or approx. 400-500mL
- increased VT = increased risk of barotrauma & decreased venous return/ CO
- decreased VT = increased risk of atelectasis
Oxygen
- 3% of the body’s oxygen is dissolved in the plasma
- PaO2=partial pressure of oxygen (mmHg)
- measures how much oxygen is in the alveoli
- SaO2 (oxygen saturation) measures the degree of oxygen bound to hemoglobin
FiO2
- set at lowest possbile level for adequate tissue perfusion
- FiO2 can be 21-100% oxygen
- try to keep
hypoxemia
- abnormally low concentration of oxygen in blood
- results from ventilation or circulatory problems
- VQ mismatching (shunting)
rate of ventilations
- normal RR= 12-20
- initially set at approx. 12-15 vent breaths/min
Positive end-expiratory pressure (PEEP)
special ventiltor setting
- used to maintain postive pressure in the lungs at the end of expiration
- improves the VQ relationship and diffusion across the alveolar- capillary membrane
- prevents: atelectasis, reduces hypoxemia, allows for lower % of FiO2
pressure support ventilation (PSV)
- preset pressure delivery augmenting pt own respiratory effort
- applies positive pressure during “spontaneous” inspiration
- can be used with all modes of ventilation
- used to: over come dead space of circuit & pts airways, decreases the work of breathing
- pt must be doing some spontaneous breathing
continuous positive airway pressure (CPAP)
- special ventilator setting
- elevates end-expiratory pressure during spontaneous breaths
- used for intubated and non-intubated pts
- used ot: maintain open airways, decrease the work of breathing
CPAP mask or BiPAP?
-used to improve oxygenation on pts who can breath on their own
-used for those experiencing sleep apnea at night
masks must be tight on the face
complications of mechanical ventilation-improper tube placement
- inflated lung vs. uninflated lung
- gastric distention
- aspiration
- facial skin necrosis
- crepitus
- drying of eyes and mucous membranes
- stress
- claustrophobia
- *need to perform oral and nasal care every 4 hrs
complications of mechanical ventilation-hospital acquired pneumonia
normal respiratory defense mechanisms bypassed
-open epiglottis
-cough/gag reflexes inhibited/ impaired
-secretions often thick and tenacious
-increases risk of atelectasis
hand washing vital in prevention
