Exam #2: Mechanical Ventilation Flashcards
What is mechanical ventilation?
Process by which FIO2 (≥ 21% room air) is moved into and out of lungs by a mechanical ventilator (doesn’t help with expiration)
Mechanical Ventilation: Not curative
- Means of supporting patients until they recover ability to breathe
- Bridge to long-term mechanical ventilation
Mechanical Ventilation: Indications
- Apnea or impending inability to breathe or protect the airway
- Acute respiratory failure
- Severe hypoxia
- Respiratory muscle fatigue
*Read notes on slide
Types of Mechanical Ventilation
- Negative Pressure Ventilation
2. Positive Pressure Ventilation
Negative Pressure Ventilation
- Involves the use of chambers that encases the chest or body
- Intermittent negative pressure pulls chest outward → air rushes in → passive expiration
- Similar to normal ventilation
- It is noninvasive ventilation that does not require an artificial airway
Positive Pressure Ventilation
- Used primarily in acutely ill patients
- Delivers air into lungs under positive pressure during inspiration → intrathoracic pressure ↑ during lung inflation (opposite of normal)
- Expiration occurs passively
Mechanical Ventilation: Modes of PPV
- Volume Ventilation
2. Pressure Ventilation
Modes of PPV: Volume Ventilation
- Predetermined tidal volume (VT) delivered with each inspiration
- Amount of pressure needed to deliver each breath varies
- Tidal volume same with each breath P
Modes of PPV: Pressure Ventilation
- Predetermined peak inspiratory pressure
- VT varies
- Careful attention needed to prevent hyper/hypoventilation
*Read notes
What do mechanical ventilation settings do?
-Regulate rate, VT, oxygen concentration and other characteristics of ventilation
Tidal Volume is based on
- How much the person weighs
- Usual is 50-600
Mechanical Ventilator Settings: What does tidal volume measure and what is the usual volume?
- Volume of gas delivered to patient during each ventilator breath
- Usual volume: 6–10 mL/kg
What are mechanical ventilator settings based on?
Patient status:
- ABGs
- ideal body weight
- current physiologic state
- LOC
- Respiratory muscle strength
Mechanical Ventilator Settings are adjusted until
Oxygenation and ventilation targets are reached
Mechanical Ventilation: Settings include
- Respiratory rate
- Tidal volume (VT)
- Fraction of inspired oxygen (FIO2)
- Positive end-expiratory pressure (PEEP)
- Pressure support
- I:E ratio
- Inspiratory flow rate and time
-Sensitivity - High-pressure limit
Mechanical Ventilator Settings: Respiratory Rate
- Number of breaths the ventilator delivers per minute
- Usual setting: 6–20 breaths/min
Mechanical Ventilator Settings: What is Oxygen Concentration (FIO2) and what is the usual range?
- Fraction of inspired oxygen (FIO2) delivered to patient.
- May be set between 21% (essentially room air) and 100%.
- Usually adjusted to maintain PaO2 level >60 mm Hg or SpO2 level >90%
Mechanical Ventilation Settings: Positive End-Expiratory Pressure (PEEP) what does it measure and what is the usual setting?
- Positive pressure applied at the end of expiration of ventilator breaths.
- Usual setting: 5 cm H2O
Mechanical Ventilation Settings: What is pressure support and what is the usual setting?
- Positive pressure used to augment patient’s inspiratory pressure.
- Usual setting: 6–18 cm H2O
Mechanical Ventilator Settings: What is I:E ratio and what is the usual setting?
- Duration of inspiration (I) to duration of expiration (E).
- Usual setting: 1:2 to 1:1.5 unless IRV is desired
Mechanical Ventilation Settings: What is inspiratory flow rate and time and what is the usual setting?
- Speed with which the VT is delivered.
- Usual setting: 40–80 L/min and time is 0.8–1.2 sec
Mechanical Ventilation Setting: What is sensitivity and what is the usual setting?
- Determines the amount of effort the patient must generate to initiate a ventilator breath.
- It may be set for pressure triggering or flow triggering.
- Usual setting: For a pressure trigger is 0.5–1.5 cm H2O below baseline pressure and for a flow trigger is 1–3 L/min below baseline flow
*Important in assist control; want sensitivity to be high
Mechanical Ventilation Settings: What is high-pressure limit and what is the usual setting?
- Regulates the maximal pressure the ventilator can generate to deliver the VT. When the pressure limit is reached, the ventilator terminates the breath and spills the undelivered volume into the atmosphere.
- Usual setting:10–20 cm H2O above peak inspiratory pressure
Mechanical Ventilation
Modes are based on
Based on how much work of breathing (WOB) patient should or can perform
Mechanical Ventilation Modes are determined by what factors?
- Ventilatory status of patient
- Respiratory drive
- ABGs
Mechanical Modes of Ventilation: Types of Support
- Controlled ventilatory support:
Ventilator does all the WOB - Assisted ventilatory support:
Ventilator and patient share WOB
Mechanical Ventilation: Assist-Control Ventilation (ACV)
- Delivers preset VT at preset frequency
- When patient initiates a spontaneous breath, preset VT is delivered
- Can breathe faster but not slower
- Allows some control over ventilation
*Read notes
Assist-control ventilation: There is a potential for
- Potential for hyperventilation
- Continuous monitoring required
Mechanical Ventilation: Synchronized intermittent mandatory ventilation
- Delivers preset VT at preset frequency in synchrony with patient’s spontaneous breathing
- Between ventilator-delivered breaths, patient is able to breathe spontaneously
- Thus, the patient receives preset FIO2 but self-regulates rate and volume of spontaneous breaths
What are potential benefits of SIMV?
- Improved patient-ventilator synchrony
- Lower mean airway pressure
- Prevention of muscle atrophy as the patient takes on more of the WOB
What are disadvantages of SIMV?
- If spontaneous breathing decreases when the preset rate is low, ventilation might not be adequately supported.
- Only patients with regular, spontaneous breathing should use low-rate SIMV.
Mechanical Ventilation: Pressure Modes include
- Pressure support ventilation
- Pressure-control ventilation
- Pressure-controlled/inverse ratio ventilation
- Airway pressure release ventilation
Pressure Support Ventilation
- Positive pressure applied to airway only during inspiration in conjunction with spontaneous respirations
- Machine senses spontaneous effort and supplies rapid flow of gas at initiation of breath
- Patient determines inspiratory length, VT, and respiratory rate
*Read notes
What is PSV used for?
Continuous ventilation and weaning
*Read notes
What are advantages of Pressure Support Ventilation?
↑ Patient comfort
↓ WOB
↓ Oxygen consumption
↑ Endurance conditioning
Pressure-Control Ventilation (PCV)
- Provides pressure-limited breath at a set rate
- May permit spontaneous breathing
- VT is not set; determined by the set pressure limit set
Pressure-Controlled/Inverse Ratio Ventilation
- Combines pressure-limited ventilation with an inverse ratio of inspiration (I) to expiration (E)
- Normal I/E is 1:2 or 1:3
- With IRV, I/E ratio begins at 1:1 and may progress to 4:1
- Progressively expands collapsed alveoli and has a PEEP-like effect
With Pressure-controlled/Inverse Ratio Ventilation, the patient needs what?
Sedation with or without paralysis
PC-IRV are indicated for what patients?
For patients with ARDS and continuing refractory hypoxemia despite high levels of PEEP
*Read notes
Airway Pressure Release Ventilation
-Permits spontaneous breathing
[Preset CPAP with short timed pressure releases
-VT varies
-Patients with ARDS who need high pressure levels
*Read notes
Mechanical Ventilation: PEEP
- Positive pressure applied to airway during exhalation, preventing alveolar collapse
- ↑ Lung volume and functional residual capacity (FRC) improves oxygenation
*Read notes
What is the major purpose of PEEP?
Maintain or improve oxygenation while limiting risk of O2 toxicity
PEEP Indications
- All mechanically ventilated patients
- Patients with ARDS
PEEP should be used with caution in
- Increased ICP
- Low CO
- Hypoventilation
Continous Positive Airway Pressure (CPAP)
- Restores FRC (Similar to PEEP)
- Pressure delivered continuously during spontaneous breathing
CPAP is commonly used to treat
Obstructive sleep apnea
CPAP should be used with caution in what patients and why?
Must be used with caution in patients with myocardial compromise because it increases WOB (because the patient bust forcible exhale against the CPAP)
BiPAP
- Bilevel positive airway pressure
- Delivers oxygen and two levels of + pressure support:
- Higher inspiratory positive airway pressure
- Lower expiratory positive airway pressure
How is BiPAP used?
Noninvasive:
Via tight-fitting face mask, nasal mask, or nasal pillows
For BiPAP, what is required of the patient?
Must be able to breath spontaneously and cooperate
What are indications for BiPAP?
- COPD patients with HF
- Acute Respiratory Failure
- Sleep apnea
- After extubation to prevent reintubation
What are contraindications for BiPAP?
- Shock
- Altered mental status
- Increased airway secretions
*Due to the risk for aspiration and the inability to remove the mask
What are complications of PPV?
- Cardiovascular complications
- Barotrauma
- Pneumomediastinum
- Volutrauma
- Alveolar Hypoventilation
- Alveolar Hyperventilation
- Ventilator Associated Pneumonia (VAP)
- Sodium and water imbalance
- Neurologic complications
- GI complications
- Musculoskeletal Complications
PPV Complications : Cardiovascular System
- ↑ Mean airway pressure transmitted to structures of thorax → vessels compressed → decreased venous return to heart:
- ↓ Preload
- ↓ Cardiac output
- ↓ BP
* PEEP increases this effect
*Read notes
PPV Complications: Barotrauma
- Air can escape into pleural space from alveoli or interstitium, accumulate, and become trapped pneumothorax
- Patients with compliant lungs are at an increased risk
What can be done prophylactically to prevent barotrauma from PPV?
Chest tubes can be placed prophylactically
*Read notes!
PPV Complications: Pneumomediastinum
- Rupture of alveoli into lung interstitium
- Progressive air movement into mediastinum and subcutaneous neck tissue
- Followed by pneumothorax
*Read notes
PPV Complications: Volutrauma
- Lung injury that occurs when large VT are used to ventilate noncompliant lungs
- Alveolar fractures and movement of fluids and proteins into alveolar spaces
PPV Complications: Alveolar Hypoventilation
- Inappropriate ventilator settings can cause leakage of air from ventilator tubing or around ET tube or tracheostomy cuff
- Lung secretions or obstruction
- Low ventilation/perfusion ratio
*Read notes
PPV Complications: Alveolar Hyperventilation
- Rate or VT set too high
- Patients with COPD at risk: Alkalosis develops if decrease PaCO2 to standard normal
- Determine cause if spontaneous hyperventilation
*Read notes
PPV Complications: Ventilator-associated pneumonia Risk Factors
- Occurs 48 hours or more after intubation
- Contaminated respiratory equipment
- Inadequate hand washing
- Environmental factors
- Impaired cough
- Colonization of oropharynx
*Read notes
Clinical Manifestations of VAP
- Fever, elevated WBC count
- Purulent or odorous sputum
- Crackles or wheezes
- Pulmonary infiltrates
Guidelines to prevent VAP
- Minimizing sedation (quicker they can breathe on their own -> weaning off of vent and therefore decreases risk for VAP)
- Early exercise and mobilization
- Subglottic secretion drainage port
- HOB elevation 30- 45 degrees
- No routine changes of ventilator circuit tubing
- Strict hand washing, wear gloves
PPV Complications: Sodium and Water Imbalance
Progressive fluid retention:
Decreased urine output
Increased sodium retention
PPV Complications: Sodium and Water Imbalance etiology
- Decreased CO
- Intrathoracic pressure changes
- Stress response (release of steroids and ADH)
*Read notes
PPV Complications: Neurologic System
Impaired venous drainage and ↑ cerebral volume → increased ICP
PPV Complications: Neurologic Management
- Elevate HOB
- Keep patient’s head in alignment
*REad notes
PPV Complications: GI
- Risk for Stress ulcers and GI Bleeding
- Decreased peristalsis
- Gastric and bowel dilation
- REad notes
PPV Complications: Stress ulcer prophylaxis
- Histamine (H2)-receptor blockers
- Proton pump inhibitors
- Enteral nutrition
PPV Complications: Gastric and Bowel dilation treatment
NG or orogastric tube for decompression
PPV Complications: Decreased peristalsis (constipation) management
Bowel regimen
*Read notes!
PPV Complications: Musculoskeletal
Loss of muscle strength and problems linked with immobility
*Read notes
PPV Complications: Musculoskeletal interventions to prevent problems
- Adequate analgesia and nutrition
- Early and progressive ambulation
- Physical and occupational therapy
*Read notes
Mechanical Ventilation: Psychosocial Needs
- Physical and emotional stress due to inability to speak, eat, move, or breathe normally
- Pain, fear, and anxiety related to tubes/machines
- Usual ADLs are extremely complicated
Psychosocial Needs Nursing Management
- Need to know (information)
- Need to regain control
- Need to hope
- Need to trust
- Need to feel safe
- Encourage hope and build trust
- Involve patient and caregivers in decision making.
Read slides 44 and 45?
?
Ventilator Disconnection
Most frequent site for disconnection is between tracheal tube and adapter
Ventilator: Alarms
- ALWAYS keep ALARMS ON
- If alarms are paused during suctioning or removal from ventilator → reactivate before leaving
*Read notes
Ventilator Malfunction
Malfunction may be due to power failure, failure of oxygen supply, etc.
What should you do if machine malfunctions?
- Disconnect patient from ventilator
- Manually ventilate with BVM and 100% O2
*Read notes
Nutritional Therapy: What can cause inadequate nutrition?
PPV and hypermetabolism can lead to inadequate nutrition
Nutritional Therapy: Patients with difficulty with oral intake include
- ET tube
- Tracheostomy
*Consult speech therapist for swallowing study
Inadequate Nutrition can decrease:
- O2 transport
- Exercise tolerance
- Serum protein
- *Weaning
- Resistance to infection
- Speed of recovery
Nutritional Therapy: Limit Carbs because
Content may lower CO2 production
*Read notes
Weaning: Process of
- Decreasing ventilator support
- Resuming spontaneous breathing
Weaning consists of three phases:
- Preweaning phase
- Weaning process
- Outcome phase
*Read notes
Preweaning or Assessment Phase
- Assess muscle strength: Negative inspiratory force
- Assess endurance: Spontaneous VT, vital capacity, minute ventilation, and rapid shallow breathing index
- Auscultate lungs
- Assess chest x-ray
Preweaning Phase: Nonrepsiratory Factors include
- Assessment of neurologic status, hemodynamics, fluid and electrolytes/acid-base balance, nutrition, and hemoglobin
- Drugs should be titrated to achieve comfort but not excessive drowsiness
*Read notes!
Weaning Process
- Awakening/Breathing Coordination, Delirium Monitoring/Management, and Early Mobility bundle:
- SBT should be at least 30 minutes but not >120 minutes
- SAT done by stopping all sedatives
The use of weaning protocol decreases
Ventilator delays
What is important during the weaning process?
- Important to rest between weaning trials
- Provide explanations regarding weaning and ongoing psychologic support
*Read notes
What position should the patient be in during the weaning process?
Sitting or semirecumbent position that is comfortable
Nursing management during weaning process
- Baseline assessment: V/S And Respiratory parameters
- Monitor for S&S
What signs and symptoms should you monitor for during the weaning process?
- Tachypnea, dyspnea
- Tachycardia, dysrhythmias
- Sustained desaturation [SpO2 <90%]
- Hypertension or hypotension
- Agitation or anxiety
- Diaphoresis
- Sustained VT<5 mL/kg
- Changes in mentation
Weaning Outcome
Weaning stops and patient is extubated
–OR–
Weaning is stopped because no further progress is made
Extubation Process
- Hyperoxygenate and suction
- Loosen ET tapes or holder
- Deflate cuff and remove tube at peak of deep inspiration
- Encourage patient to deep breath and cough
- Supplemental O2
- Careful monitoring after extubation
*Read notes
