Mechanical Ventilation Flashcards
Mechanical Ventilation
The use of a machine or device to assist or replace ventilation
Ventilation = movement of air in & out of the lungs
Vs
Respiration = movement of gases across a membrane
ie. alveoli & capillaries
Types of Ventilation
(2)
Negative Pressure (LOW)
- Inspiration drives negative pressure
- INC space in thoracic cavity = INC lung capacity (expanded) = pressure inside the lungs is now lower than the atmosphere
- EXPIRATION = high pressure in the lungs > wants to go out in the atmosphere
Positive Pressure:
- Air is getting forced in (compared to being sucked in)
- ie blowing up a balloon
Indication: mm of inspiration are insufficient
Administration of Mechanical Ventilation
(2)
Invasive (intubation): passage of artifical airway into trachea
1. Endotracheal tube (ETT) - mouth/nose
2. Tracheostomy - incision into trachea (anterior neck) to get tube in
Non-invasive:
- Nasal mask
- Complete face mask
Indications for MV
(4 - 6 + 4)
Severe hypoventilation, hypoxia, or hypoxemia
- Apnea - not breathing
- Acute hypercarbia (that is not quickly reversible) = elevated CO2 in blood
- PaO2 < 50 mmHg w/ supplemental O2
- Repiratory rate > 30 breaths/min (tachypenic)
- Vital capacity less than 10 L/min
- Inspiratory force <-25 cm H2O
Central Depression
- Decreased level of consciousness
- Anesthesia or deation
- Head injury
- Drug overdose
Decrease work of breathing & respiratory mm fatigue
Poor pulmonary hygiene (secretion clearance) - NOT effective of clearing airways
Complications
(5)
- Barotrauma: excessive pressure
Can lead to pneumothorax
WORSE complication - Volutrauma: excessive volume
Alveolar overdistension - Ventilator Acquired Pneumonia (VAP)
Micro-aspiration of gastric contents or oral secretions - Diaphragm atrophy: as a rsult of disuse
Is not being used - mechanical ventilation is doing all the work - Hemodynamic compromise: flow of blood
Overinflated lungs > compression of great vessels > DEC venous return > DEC cardiac output = less blood going out to the system
Types of Mechanical Ventilation Breaths
(3)
Mandatory: Completely dependent
- Ventilation is initiated, controlled, and ended by the ventilator
Assisted
- Ventilation initiated by the patient but controlled & ended by the ventilator
- Ex. Bench press spotter - initated by the presser BUT struggles at the end & spotter steps in to help
Spontaneous
- Ventilation is initiated, controlled, and ended by the patient BUT the volume & pressure of the breath delivered by the ventilatory is based on patient demand
Modes of Ventilation
(3)
Invasive
- Continuous Mandatory Ventilation (CMV)
- Assist Control ventilation (ACV)
- Syncronized Intermittent Mandatory Ventiliation (SIMV)
Non-Invasive
- Continuous Positive Airway Pressure (CPAP)
Continuous Mandatory Ventilation (CMV)
- Tidal volume & preset respiratory rate delivered by ventilator
- Ventilator provides total support (patient has no control) completely sedated ex. Sx or high level SCI
Assist Control Ventilation (ACV)
3
Tidial volume & minimum number of mandatory breaths per minute (respiratory rate) delivered by the ventilator. This will deliver a minimum minute ventilation
- Minute ventilation = amount of air moving in/out per min > product of TV x RR
Patient able to initiate inspiration but sitll receives preset tidial volume
- If pt cannot make an adequate respiratory effort
If patient foes not initiate a breath within a specific time period, the ventilatory will deliver a breath to maintian the respiratory rate (preset)
Disadvantage:
- Higher RR than what is set by the machine - still receive a full TV = minute ventilation is INC > respiratory alkolosis OR become hyperinflated & distention/rupture of alveoli
Synchronized Intermittent Mandatory Ventilation (SIMV)
(3)
- Preset mandatory tidal volume & respiratory rate delivered by ventilator
- Patient able to breath spontaneously between ventilator breaths
- Spontaneous patient-initiated breaths are synchronized w/ ventilator breath
** IF the pt initates breath - ventilator will just adjust accordingly - this prevents STACKED breathing
Continuous Positive Airway Pressure (CPAP)
(6)
- Patient spontaneous breaths are augmented w/ a perdetermined level of (positive) pressure delivered throughout the entire respiratory cycle (inspiratory & expiratory phases)
- Keeps airways open continuously in patients who can breathe spontaneously on their own but require assistance keeping airways unobstructed
- Commonly used as a weaning mode for those who are intubated or an attempt to postone intubation
- When used with a mask, it is considered noninvasive ventilation
- Help prevent alveolar collapse, improve FRC, and enhance oxygenation
- Used to patients with obstructive sleep apnea, adults with neuromuscular diseases, acute & chronic ventilatory failure & children w/ acute respiratory failure
Ventilator Adjustments
(2)
- Positive End Expiratory Presure (PEEP)
- Pressure Support Ventilation (PSV)
Positive End Expiratory Pressure (PEEP)
4
- A positive pressure is applied to the lung at the end of the expiratory phase of ventilation
- Helps keep alveoli open (preventing alveoli collapse) during expiration & reduces pulmonary shunting
V/Q mismatch - good perfusion but issues w/ ventilation - High levels of PEEP can cause excessive alveolar distension (volutrauma) or pulmonary barotrauma (ie pneunothorax = worse complication)
- Complications of PEEP may include:
- INC physiological dead space
Excess air (opposite of shunting) - inhaled a lot of air not participating in gas exchange
- DEC CO
- Ventilator-Associated Pneumonia (VAP)
- Increased risk of barotrauma
Pressure Support Ventilation (PSV)
(3)
- Patient-initiated breaths are augmented by the ventilator to maintain a constant preset inspiratory pressure
- Patient initiates all breath & controls the respiratory rate & inspiratory time
- Helps to decrease work od breathing - INSPIRATION aspect
Augmented breath for assistance
No safety net in place for this type
Communication
(2)
- Decreased ability to communicate verbally when intubated or wearing mask
- Alternative methods of communication:
- Writing
- Hand signals - common phrases ESP. yes/no - use close-end questions
- Communication boards - point at pictures to explain what they want
Weaning
(2)
- The process of decreasing mechanical ventilation - ventilator INDEPENDENT
- A spontaneous breathing trial while being closely monitored is typically performed to assess readiness to behin weaning process
