Ventilator Check: A Guide to Patient-Ventilator Assessment

A ventilator check is a systematic assessment of the mechanically ventilated patient, artificial airway, ventilator, breathing circuit, alarms, humidification system, and monitored respiratory variables.

Its purpose is to confirm that ventilation and oxygenation are adequate while identifying patient-related or equipment-related problems before they become dangerous.

A proper ventilator check involves much more than documenting machine settings. The respiratory therapist must evaluate how the patient is responding to ventilatory support, whether the prescribed settings are being delivered correctly, and whether adjustments or interventions are necessary.

What is a Ventilator Check?

A ventilator check is a structured evaluation of the entire patient-ventilator system. It combines physical assessment with review of ventilator settings, measured values, airway pressures, respiratory mechanics, alarms, waveforms, gas exchange, artificial airway function, and circuit integrity.

Mechanical ventilation is a form of life support, so the patient cannot be evaluated by looking only at the ventilator screen. A machine may be functioning correctly while the patient is deteriorating, or the patient may appear unstable because of a problem with the airway, circuit, humidification system, or ventilator itself.

For this reason, the respiratory therapist should continually ask several questions:

• Is the patient receiving adequate oxygenation?
• Is ventilation sufficient to maintain appropriate carbon dioxide elimination?
• Is the artificial airway patent and correctly positioned?
• Are ventilator settings appropriate for the patient’s current condition?
• Is the patient comfortable and synchronized with the ventilator?
• Are airway pressures acceptable?
• Is complete exhalation occurring?
• Are alarms properly configured?
• Are there any leaks, obstructions, or equipment problems?
• Have important values changed since the previous assessment?

Note: The purpose is not simply to verify that the machine is operating. The goal is to determine whether the patient and ventilator are working together safely and effectively.

Why Are Ventilator Checks Important?

Ventilator checks are important because they help ensure that mechanical ventilation remains safe, effective, and appropriate for the patient’s changing condition. A ventilator can be functioning properly while the patient develops airway obstruction, worsening lung compliance, gas trapping, hypoxemia, or patient-ventilator asynchrony.

Routine checks allow clinicians to identify these problems early by evaluating the patient, artificial airway, circuit, settings, pressures, alarms, waveforms, and gas exchange together. They also help confirm that ordered settings are being delivered correctly and that the patient is tolerating support.

By comparing current findings with previous assessments, respiratory therapists can recognize meaningful trends and intervene before minor abnormalities progress into serious complications.

How Often Should a Ventilator Check Be Performed?

Patient-ventilator assessments should be performed regularly throughout mechanical ventilation. Depending on the patient’s condition, assessments may occur approximately every 1 to 4 hours.

A critically unstable patient may require nearly continuous bedside observation. Stable patients may be assessed at longer intervals according to facility policy and clinical judgment.

Additional ventilator checks are generally appropriate after:

• Intubation or tracheostomy placement
• Changes in ventilator settings
• Changes in patient condition
• Sudden oxygen desaturation
• Development of respiratory distress
• Activation of significant ventilator alarms
• Transport or repositioning
• Suctioning when major airway changes occur
• Changes in sedation or level of consciousness
• Procedures affecting respiratory function

Note: Trend monitoring is especially important because gradual changes in pressure, volume, respiratory rate, or oxygenation may reveal deterioration before a major emergency develops.

Preparing for a Ventilator Check

Preparation helps ensure that the assessment is organized and complete.

The respiratory therapist may need equipment such as:

• Stethoscope
• Pulse oximeter
• Oxygen analyzer
• Cuff-pressure manometer
• Timing device
• Suction equipment
• Airway supplies
• Humidification supplies
• Manual resuscitation bag
• Appropriate oxygen source

Many modern ventilators provide extensive monitoring, but auxiliary equipment remains important for confirming findings and responding to emergencies. The patient’s medical record should also be reviewed before or during the assessment.

Important information may include:

• Admitting diagnosis
• Current ventilator orders
• Medication administration
• Sedation level
• Vital signs
• Arterial blood gas results
• Chest radiographs
• Laboratory values
• Recent procedures
• Progress notes
• Previous ventilator checks
• Previous airway pressures
• Previous tidal volumes and minute ventilation

Note: Reviewing this information establishes the clinical context needed to interpret current findings.

Begin With the Patient

A ventilator check should begin by assessing the patient rather than immediately looking at the ventilator screen. This principle is particularly important when alarms are sounding or respiratory deterioration occurs. The patient may provide the most important clue about what is wrong.

General Appearance

The respiratory therapist should observe the patient’s overall condition.

Important findings include:

• Level of consciousness
• Skin color
• Pallor
• Cyanosis
• Capillary refill
• Diaphoresis
• Anxiety
• Agitation
• Activity level
• Extremity appearance
• Signs of discomfort
• Evidence of respiratory distress

Note: The patient’s position should also be evaluated because changes in body position can affect oxygenation, airway patency, lung expansion, and ventilator interaction.

Vital Signs

Vital signs help reveal how the patient is responding to mechanical ventilation.

Important measurements include:

• Respiratory rate
• Heart rate
• Blood pressure
• Temperature
• Oxygen saturation

An increasing respiratory rate may indicate pain, anxiety, hypoxemia, increased respiratory drive, inadequate ventilatory support, or patient-ventilator asynchrony.

Blood pressure is particularly important when higher airway pressures or PEEP are being used. Positive pressure ventilation can reduce venous return to the heart and may decrease cardiac output in susceptible patients.

Respiratory Effort

The respiratory therapist should observe how much work the patient is performing.

Signs of increased work of breathing may include:

• Accessory muscle use
• Retractions
• Nasal flaring
• Paradoxical breathing
• Tachypnea
• Visible distress
• Forceful inspiratory effort
• Difficulty triggering the ventilator

Note: A patient making excessive effort to initiate assisted breaths may have an insensitive trigger setting, auto-PEEP, inappropriate pressure support, or another problem increasing the work of breathing.

Chest Assessment

The physical examination provides information that cannot be obtained from ventilator values alone.

Chest Movement

The chest should be inspected for:

• Symmetry of expansion
• Respiratory rate
• Respiratory rhythm
• Chest-wall movement
• Diaphragmatic movement
• Retractions
• Accessory muscle use
• Chest-wall instability

Note: Asymmetrical chest expansion may suggest endotracheal tube migration, mucus plugging, atelectasis, pneumothorax, or unilateral lung disease.

Auscultation

Breath sounds should be compared bilaterally in corresponding lung regions.

Abnormal findings may include:

• Crackles
• Rhonchi
• Wheezing
• Diminished breath sounds
• Absent breath sounds
• Bronchial or bronchovesicular sounds in unexpected locations

Wheezing may suggest bronchospasm or airway narrowing. Rhonchi may indicate secretions. Crackles can occur with pulmonary edema, atelectasis, or other conditions involving fluid or collapsed airspaces.

A sudden loss of breath sounds requires immediate investigation. For example, absent breath sounds on one side combined with sudden deterioration may suggest pneumothorax or migration of the endotracheal tube into a mainstem bronchus.

Percussion and Tracheal Position

Chest percussion can provide additional information when clinically appropriate.

Dullness may occur with:

• Atelectasis
• Consolidation
• Pleural effusion

Hyperresonance may occur with:

• Pneumothorax
• Pulmonary hyperinflation
• Severe air trapping

Note: Tracheal position should also be observed. Significant deviation may occur with severe atelectasis or tension pneumothorax.

Artificial Airway Assessment

The endotracheal or tracheostomy tube is a critical part of the ventilator system.

The airway must remain:

• Properly positioned
• Secure
• Patent
• Free of significant obstruction
• Adequately sealed when a cuff is used

Tube depth should be compared with previously documented measurements. Unexpected movement may indicate partial extubation or advancement into a mainstem bronchus.

Potential causes of airway obstruction include:

• Thick secretions
• Mucus plugs
• Tube kinking
• Patient biting
• Blood or debris
• Mucosal edema
• Excessive cuff inflation
• Small internal tube diameter

Note: Airway obstruction typically increases resistance and may cause a rise in peak inspiratory pressure.

Suctioning During a Ventilator Check

If suctioning is indicated, it is often performed before formal ventilator measurements are recorded. This allows secretions to be removed before pressures and volumes are documented, providing a more accurate representation of the patient’s condition after basic airway problems have been corrected.

Following suctioning, the respiratory therapist should evaluate and document:

• Amount of secretions
• Color
• Thickness
• Odor
• Presence of blood
• Patient tolerance

Note: Large amounts of thick secretions may contribute to increased airway resistance and high-pressure alarms.

Cuff Pressure Assessment

Cuff pressure should be checked regularly in patients with cuffed artificial airways. The cuff must create enough pressure to provide an effective seal but should not exert excessive pressure against the tracheal wall.

Insufficient cuff pressure can contribute to:

• Air leaks
• Reduced delivered tidal volume
• Inaccurate ventilator measurements
• Aspiration risk
• Difficulty maintaining PEEP

Excessive cuff pressure may impair tracheal mucosal blood flow and contribute to tissue injury. Cuff pressure is generally maintained no higher than approximately 30 cm H₂O, while still providing an adequate seal.

It should commonly be checked at least once per shift and after events such as:

• Tube movement
• Repositioning
• Cuff adjustment
• Development of an audible leak
• Unexpected change in exhaled tidal volume

Inspecting the Ventilator Circuit

The breathing circuit should be inspected from the patient connection back toward the ventilator.

Important problems include:

• Loose connections
• Disconnections
• Cracked tubing
• Kinking
• Obstruction
• Excessive condensate
• Improper humidifier setup
• Expiratory valve problems
• Blocked filters
• Leaks

Circuit leaks commonly produce decreased airway pressure and reduced exhaled tidal volume. Circuit obstruction tends to increase airway pressure and may reduce ventilation.

Condensate should be drained appropriately because accumulated water can interfere with airflow, increase resistance, and contribute to alarm activation.

Humidification Assessment

Patients with artificial airways bypass much of the upper airway, which normally warms and humidifies inspired gas. Therefore, adequate humidification is essential.

Ventilator systems may use:

• Heated humidifiers
• Pass-over humidifiers
• Heat-moisture exchangers

The respiratory therapist should verify that the selected humidification system is functioning correctly.

Inadequate humidification can contribute to:

• Thick secretions
• Mucus plugging
• Airway obstruction
• Increased airway resistance

Note: Excessive condensation can also create circuit problems, including increased resistance or interference with flow.

Checking Ventilator Settings

The ventilator settings should be compared with the prescribed values.

Depending on the ventilation mode, important settings may include:

• Ventilation mode
• Mandatory respiratory rate
• Tidal volume
• Inspiratory pressure
• FiO₂
• PEEP
• CPAP
• Pressure support
• Inspiratory flow
• Flow waveform
• Inspiratory time
• I:E ratio
• Trigger sensitivity
• Rise time
• Cycling criteria

Note: The clinician should confirm that the machine is programmed correctly, but this is only part of the assessment. A prescribed setting may no longer be appropriate if the patient’s condition has changed. The therapist must determine whether the current settings are actually meeting the patient’s physiologic needs.

Set Values Versus Measured Values

Ventilator checks should distinguish between what is set and what is actually delivered or measured.

Important monitored values include:

• Exhaled tidal volume
• Total respiratory rate
• Spontaneous respiratory rate
• Minute ventilation
• Peak inspiratory pressure
• Plateau pressure
• PEEP
• Mean airway pressure
• FiO₂
• Inspiratory and expiratory times

An exhaled tidal volume substantially lower than expected may indicate leakage somewhere in the system.

Potential sources include:

• Loose circuit connection
• Cuff leak
• Bronchopleural fistula
• Circuit defect
• Faulty exhalation valve

Note: Comparing inspired and expired volumes can help identify these problems.

Evaluating Tidal Volume

Tidal volume is one of the most important monitored values during mechanical ventilation. The exhaled tidal volume should be evaluated in relation to the patient’s predicted body weight and clinical condition.

Lung-protective ventilation commonly emphasizes appropriately small tidal volumes to reduce the risk of ventilator-induced lung injury. The clinician should also determine whether spontaneous and mandatory tidal volumes need to be evaluated separately.

In modes that allow substantial spontaneous breathing, a normal mandatory tidal volume does not necessarily mean spontaneous breaths are adequate.

Respiratory Rate and Minute Ventilation

Minute ventilation represents the total volume of gas moved through the respiratory system each minute. It is determined by the relationship between tidal volume and respiratory rate. An increase or decrease in minute ventilation may contribute to changes in PaCO₂ and acid-base balance.

Low minute ventilation may result from:

• Reduced respiratory drive
• Sedation
• Apnea
• Circuit leaks
• Low tidal volume
• Low respiratory rate
• Inadequate ventilator support

High minute ventilation may occur with:

• Pain
• Anxiety
• Fever
• Hypoxemia
• Restlessness
• Increased respiratory drive
• Patient-ventilator asynchrony

Note: Ventilator values should always be correlated with blood gases and the patient’s clinical condition.

Peak Inspiratory Pressure

Peak inspiratory pressure (PIP) is the highest airway pressure reached during inspiration.

Peak pressure reflects the pressure required to:

• Overcome airway resistance
• Move gas through the artificial airway
• Move gas through the ventilator circuit
• Expand the lungs
• Expand the chest wall

Note: Because it is influenced by both resistance and compliance, a change in peak pressure should prompt further evaluation.

Causes of Increased Peak Inspiratory Pressure

Peak pressure may increase because of:

• Secretions
• Bronchospasm
• Endotracheal tube obstruction
• Tube kinking
• Patient biting
• Coughing
• Increased inspiratory flow
• Reduced lung compliance
• Pneumothorax
• Pulmonary edema
• Atelectasis
• Patient-ventilator asynchrony

Note: A sudden increase should never be dismissed as a simple machine issue.

Causes of Decreased Peak Inspiratory Pressure

A decrease in peak pressure may reflect improved resistance or compliance, but it can also indicate:

• Circuit leak
• Cuff leak
• Partial disconnection
• Complete disconnection

Note: The patient and circuit should therefore be assessed whenever a major unexplained change occurs.

Plateau Pressure

Plateau pressure is measured during an inspiratory hold when airflow has temporarily stopped. Because there is little or no flow during the measurement, plateau pressure more closely reflects the pressure required to distend the respiratory system.

The patient should ideally be passive during the measurement. Patient effort can distort the result. Fighting the ventilator may produce an artificially high value, while active inspiratory assistance may lower the measured pressure.

Plateau pressure is useful for evaluating:

• Static compliance
• Lung distending pressure
• Risk of ventilator-induced lung injury

Note: Lung-protective strategies generally attempt to keep plateau pressure below approximately 28 cm H₂O when possible.

Peak Pressure Versus Plateau Pressure

Comparing peak and plateau pressures helps distinguish airway resistance problems from compliance problems.

Increased Peak Pressure With Stable Plateau Pressure

If peak pressure rises while plateau pressure remains relatively unchanged, increased airway resistance is likely.

Possible causes include:

• Bronchospasm
• Secretions
• Airway edema
• Artificial airway obstruction
• Kinked endotracheal tube
• Patient biting the tube

Increased Peak and Plateau Pressures

If both peak and plateau pressures rise, decreased respiratory-system compliance should be considered.

Possible causes include:

• ARDS
• Pulmonary edema
• Pneumonia
• Atelectasis
• Pneumothorax
• Pleural effusion
• Pulmonary fibrosis
• Hyperinflation
• Chest-wall restriction

Note: This comparison is one of the most useful bedside tools for evaluating changes in respiratory mechanics.

Driving Pressure

Driving pressure represents the pressure used to expand the respiratory system above PEEP.

It is commonly calculated as:

Driving pressure = Plateau pressure − PEEP

Driving pressure is another important component of lung-protective ventilation.

Values greater than approximately 15 cm H₂O have been associated with worse outcomes in critically ill patients, so clinicians generally attempt to minimize driving pressure when possible. This must be considered together with tidal volume, compliance, plateau pressure, PEEP, and the patient’s overall condition.

PEEP and End-Expiratory Pressure

Positive end-expiratory pressure (PEEP) maintains positive pressure in the respiratory system at the end of expiration. PEEP may improve oxygenation by helping prevent alveolar collapse and increasing functional residual capacity.

During the ventilator check, the respiratory therapist should verify both the set PEEP and the pressure that actually remains at the end of exhalation. Unexpected pressure above the set PEEP may indicate auto-PEEP.

Auto-PEEP

Auto-PEEP, also called intrinsic PEEP, occurs when expiration is incomplete before the next inspiration begins. Air becomes trapped in the lungs, leaving positive pressure at end expiration.

Common causes include:

• High respiratory rate
• Short expiratory time
• High tidal volume
• Airway obstruction
• Bronchospasm
• Secretions
• Severe obstructive lung disease

Auto-PEEP is particularly important in patients with asthma or emphysema.

It may cause:

• Increased work of breathing
• Trigger difficulty
• Patient-ventilator asynchrony
• Hyperinflation
• Increased intrathoracic pressure
• Reduced venous return
• Hemodynamic instability

Detecting Auto-PEEP With Waveforms

One of the most useful methods for recognizing air trapping is the flow-time waveform. During normal exhalation, expiratory flow should return to baseline before the next breath begins.

If expiratory flow has not returned to baseline when the next inspiration starts, the patient has not completely exhaled. This pattern suggests air trapping and possible auto-PEEP.

Management may involve increasing expiratory time by adjusting factors such as:

• Respiratory rate
• Inspiratory time
• Inspiratory flow
• Tidal volume

Note: The underlying airway obstruction should also be addressed when present.

Trigger Sensitivity

Trigger sensitivity determines how much patient effort is required to initiate an assisted breath. With pressure triggering, a setting requiring approximately −1 to −2 cm H₂O of patient effort is commonly considered reasonable.

If trigger sensitivity is too insensitive, the patient must generate excessive inspiratory effort before the ventilator responds. This can increase work of breathing and cause missed triggering.

If sensitivity is too responsive, the ventilator may auto-trigger because of:

• Circuit movement
• Water in the tubing
• Leaks
• Cardiac oscillations
• Other disturbances

Note: The therapist should therefore evaluate both the numerical trigger setting and the patient’s actual ability to trigger comfortably.

Patient-Ventilator Asynchrony

Patient-ventilator asynchrony occurs when the patient’s respiratory effort does not match the ventilator’s timing, flow, triggering, or cycling.

Common categories include:

• Trigger asynchrony
• Flow asynchrony
• Cycle asynchrony
• Mode asynchrony

Possible causes include:

• Trigger sensitivity set incorrectly
• Inadequate inspiratory flow
• Excessive inspiratory flow
• Incorrect inspiratory time
• Inappropriate rise time
• Auto-PEEP
• Inadequate pressure support
• Excessive pressure support
• Incorrect tidal volume
• Unsuitable ventilation mode

Note: Asynchrony can increase work of breathing, worsen patient discomfort, and interfere with effective ventilation.

Ventilator Waveforms

Modern ventilators provide graphic displays that should be included in routine assessment.

Common scalar waveforms include:

• Pressure versus time
• Flow versus time
• Volume versus time

Common loops include:

• Pressure-volume loops
• Flow-volume loops

These displays provide valuable information about respiratory mechanics and ventilator interaction.

Waveforms may help detect:

• Auto-PEEP
• Air trapping
• Circuit leaks
• Increased airway resistance
• Decreased compliance
• Inadequate inspiratory flow
• Missed triggering
• Double triggering
• Premature cycling
• Delayed cycling
• Overdistention

Note: Patient-ventilator asynchrony may be intermittent, so waveforms sometimes need to be observed for longer than only a few breaths.

Pressure-Volume and Flow-Volume Loops

Pressure-volume loops provide information about lung compliance and overdistention. A characteristic beak or flattening near the upper portion of the pressure-volume loop may indicate overdistention.

Flow-volume loops can help evaluate:

• Airway obstruction
• Bronchodilator response
• Leaks
• Auto-PEEP
• Changes in expiratory flow

Note: Ventilator graphics should be interpreted together with pressures, volumes, physical examination, and the patient’s condition.

P0.1 and Respiratory Drive

Some ventilators provide P0.1, also called P100, as a measurement of respiratory drive. It reflects the negative airway pressure generated during the first 100 milliseconds of an inspiratory effort.

More negative values generally indicate increased respiratory drive. Values around −0.5 to −5 cm H₂O may be considered acceptable during patient-triggered mechanical ventilation.

Increasingly negative values may suggest that ventilator support is not adequately meeting patient demand. Because respiratory effort varies between breaths, repeated measurements may be more useful than a single reading.

Ventilator Alarm Assessment

Ventilator alarms are essential safety systems. They should be appropriately set, functional, and individualized for the patient’s condition.

Important alarms include:

• High pressure
• Low pressure
• Disconnection
• Low tidal volume
• High tidal volume
• Low minute ventilation
• High minute ventilation
• Low PEEP
• High respiratory rate
• Apnea
• High FiO₂
• Low FiO₂
• Power failure
• Gas-supply failure
• Humidification problems

Note: An alarm should never simply be silenced without determining its cause.

High-Pressure Alarm

A high-pressure alarm indicates that airway pressure has reached or exceeded the established limit.

Possible causes include:

• Secretions
• Mucus plugging
• Bronchospasm
• Coughing
• Tube biting
• Kinked tubing
• Airway obstruction
• Decreased compliance
• Pneumothorax
• Pulmonary edema
• Water in the circuit
• Patient-ventilator asynchrony

Note: The high-pressure alarm may commonly be set approximately 10 to 15 cm H₂O above the usual peak inspiratory pressure, depending on the clinical situation. The alarm identifies a problem but does not identify the exact cause.

Low-Pressure Alarm

A low-pressure alarm generally suggests that pressure is not being maintained within the ventilator system.

Possible causes include:

• Circuit disconnection
• Loose connection
• Cuff leak
• Circuit leak
• Partial extubation
• Improper alarm setting

Note: The low-pressure limit may be positioned approximately 5 to 10 cm H₂O below the normal peak inspiratory pressure, depending on the ventilator and patient.

Low Tidal Volume Alarm

A low exhaled tidal-volume alarm may be caused by:

• Circuit disconnection
• Cuff leak
• Circuit leak
• Bronchopleural fistula
• Shallow spontaneous breathing
• Inadequate support
• Coughing
• Patient-ventilator asynchrony

Note: Some systems use a low-volume limit approximately 100 mL below the expected exhaled mechanical tidal volume, although alarm settings should always be individualized.

Low PEEP Alarm

A low-PEEP or low-CPAP alarm can indicate:

• Circuit disconnection
• Leakage
• Cuff leak
• PEEP valve malfunction
• Failure to maintain airway pressure

Note: Loss of PEEP can be clinically significant in patients who depend on elevated end-expiratory pressure to maintain oxygenation.

Apnea Alarm

The apnea alarm detects the absence of expected spontaneous breathing. A common apnea delay may be approximately 15 to 20 seconds, depending on the patient and ventilator.

Potential causes of apnea include:

• Sedation
• Anesthesia
• Neurologic impairment
• Reduced respiratory drive
• Extremely low spontaneous respiratory rate

Note: Some ventilators automatically provide backup ventilation when apnea occurs.

Assessing Oxygenation and Ventilation

Ventilator values alone cannot determine whether oxygenation and ventilation are adequate. Physiologic measurements should be incorporated into the assessment.

Pulse Oximetry

Pulse oximetry provides continuous estimation of arterial oxygen saturation.

A falling oxygen saturation should prompt evaluation of:

• Airway patency
• FiO₂
• PEEP
• Breath sounds
• Tube position
• Secretions
• Pulmonary mechanics
• Ventilator function
• Hemodynamic status

Arterial Blood Gases

Arterial blood gases provide important information about:

• pH
• PaCO₂
• PaO₂

Note: PaCO₂ reflects the effectiveness of alveolar ventilation, while PaO₂ helps assess oxygenation. Changes in blood gases may indicate that ventilator adjustments are required.

Capnography

End-tidal carbon dioxide monitoring and capnography provide additional information about ventilation.

Changes may reflect alterations in:

• Ventilation
• Perfusion
• Airway position
• Circuit integrity
• Cardiac output

Note: Capnography should be interpreted together with blood gases and the patient’s overall condition.

Lung-Protective Ventilation During the Check

A ventilator check should include an assessment of whether the current strategy is consistent with lung-protective ventilation.

Important considerations include:

• Appropriate tidal volume
• Plateau pressure control
• Driving pressure
• Appropriate PEEP
• FiO₂ requirements
• Prevention of overdistention
• Avoidance of excessive airway pressure
• Prevention of auto-PEEP
• Patient-ventilator synchrony

Note: The goal is to provide adequate gas exchange while minimizing the risk of ventilator-induced lung injury.

Sudden Deterioration During Mechanical Ventilation

A suddenly deteriorating ventilated patient requires immediate assessment. The respiratory therapist should quickly determine whether the problem originates from:

• The patient
• The artificial airway
• The breathing circuit
• The ventilator

Major causes of sudden ventilatory difficulty include:

• Tension pneumothorax
• Airway obstruction
• Right mainstem bronchus intubation
• Bronchospasm
• Mucus plugging
• Pulmonary edema
• Auto-PEEP
• Circuit disconnection
• Major circuit leak
• Ventilator malfunction

Note: When a serious ventilator or circuit problem is suspected, the patient may need to be disconnected from the ventilator and manually ventilated with a resuscitation bag connected to oxygen. If manual ventilation improves the situation, a ventilator or circuit problem becomes more likely. Patient support always takes priority over troubleshooting the machine.

Pre-Use Ventilator Verification

Ventilator checks also begin before the patient is connected. The ventilator should be assembled and tested before use. A test lung may be connected to verify that the ventilator delivers the intended:

• Respiratory rate
• Tidal volume
• Inspiratory pressure
• Oxygen concentration
• Inspiratory time
• I:E ratio
• PEEP

Modern ventilators usually perform a power-on self-test that evaluates sensors, internal systems, and system leaks. The ventilator should not be placed into service if operational verification fails.

Important systems that should be checked include:

• Battery backup
• Power-loss alarm
• Oxygen analyzer
• Gas-supply alarms
• High-pressure alarm
• Low-pressure alarm
• Disconnect alarm
• Apnea alarm
• Airway-pressure monitoring

Note: Pre-use testing reduces the possibility of connecting a malfunctioning or incorrectly configured ventilator to a patient.

Documentation

A complete ventilator check should be documented clearly.

Documentation may include:

• Ventilator mode
• Set respiratory rate
• Total respiratory rate
• Tidal volume
• Exhaled tidal volume
• Minute ventilation
• FiO₂
• PEEP
• Pressure support
• Inspiratory pressure
• Inspiratory flow
• Inspiratory time
• Peak inspiratory pressure
• Plateau pressure
• Driving pressure
• Auto-PEEP
• Breath sounds
• Oxygen saturation
• Artificial airway position
• Cuff pressure
• Secretions
• Humidification status
• Alarm settings
• Patient-ventilator synchrony
• Interventions performed

Note: The value of documentation increases when each assessment is compared with previous measurements. A gradual increase in airway pressure or decrease in exhaled tidal volume may be clinically meaningful even when the current value is not yet severely abnormal.

Why Trends Matter

A single ventilator measurement provides only a snapshot. Trends can reveal whether the patient’s condition is improving or worsening.

Examples include:

• Rising peak pressure with stable plateau pressure suggesting increasing airway resistance
• Rising peak and plateau pressures suggesting worsening compliance
• Decreasing exhaled tidal volume suggesting a developing leak
• Increasing respiratory rate suggesting distress
• Increasing FiO₂ requirements suggesting worsening oxygenation
• Increasing auto-PEEP suggesting worsening air trapping
• Increasingly negative P0.1 suggesting greater respiratory drive

Note: Trend recognition allows clinicians to intervene before abnormalities become severe.

Ventilator Check Practice Questions

1. What is a ventilator check?
A ventilator check is a systematic assessment of the mechanically ventilated patient, artificial airway, ventilator settings, breathing circuit, alarms, and monitored respiratory variables.

2. What is the primary purpose of a ventilator check?
The primary purpose is to confirm that ventilation and oxygenation are adequate while identifying patient-related, airway-related, or equipment-related problems before they become serious.

3. How often should patient-ventilator assessments generally be performed?
Patient-ventilator assessments are generally performed every 1 to 4 hours, depending on the severity of the patient’s condition.

4. What should be assessed first during a ventilator check?
The patient’s overall clinical condition should be assessed first before focusing on ventilator numbers and settings.

5. What patient findings should be observed at the beginning of a ventilator check?
The clinician should assess level of consciousness, skin color, respiratory effort, chest movement, vital signs, oxygen saturation, comfort, and signs of respiratory distress.

6. Why is it important to review the patient’s medical record before or during a ventilator check?
The medical record provides clinical context through diagnoses, ventilator orders, medications, laboratory results, arterial blood gases, imaging, and previous respiratory assessments.

7. Why should the ventilator circuit be inspected during a ventilator check?
The circuit should be inspected to identify leaks, disconnections, kinks, obstructions, accumulated condensate, or other problems that could interfere with ventilation.

8. Why is humidification important for a mechanically ventilated patient with an artificial airway?
An artificial airway bypasses the upper airway’s normal humidification function, so adequate humidification helps prevent thick secretions, mucus plugging, and airway obstruction.

9. What should be evaluated when assessing an endotracheal or tracheostomy tube?
The tube should be assessed for proper position, security, patency, secretions, kinking, biting, obstruction, and evidence of displacement.

10. Why is suctioning often performed before formal ventilator measurements are recorded?
Suctioning removes secretions that may alter airway resistance and ventilator pressures, allowing measurements to better reflect the patient’s condition after the airway has been cleared.

11. What cuff pressure should generally not be exceeded in a mechanically ventilated patient?
Cuff pressure should generally remain no higher than approximately 30 cm H₂O while still maintaining an adequate airway seal.

12. What can happen if artificial airway cuff pressure is too low?
A cuff pressure that is too low can cause an air leak, reduce delivered tidal volume, interfere with PEEP, and increase the risk of aspiration.

13. What can happen if artificial airway cuff pressure is excessively high?
Excessive cuff pressure can reduce blood flow to the tracheal mucosa and contribute to tissue injury.

14. What is peak inspiratory pressure?
Peak inspiratory pressure is the highest airway pressure reached during inspiration and reflects the pressure required to overcome airway resistance and expand the lungs and chest wall.

15. What can cause an increase in peak inspiratory pressure?
Causes include bronchospasm, secretions, airway obstruction, a kinked endotracheal tube, biting, coughing, increased inspiratory flow, decreased compliance, or patient-ventilator asynchrony.

16. What is plateau pressure?
Plateau pressure is the airway pressure measured during an inspiratory hold when airflow has stopped, making it a useful indicator of the pressure required to distend the respiratory system.

17. What does an increase in peak inspiratory pressure with an unchanged plateau pressure suggest?
This pattern suggests an increase in airway resistance, such as from bronchospasm, secretions, or artificial airway obstruction.

18. What does an increase in both peak inspiratory pressure and plateau pressure suggest?
An increase in both pressures suggests decreased respiratory-system compliance, which may occur with conditions such as pulmonary edema, ARDS, atelectasis, pneumothorax, or pleural effusion.

19. How is driving pressure calculated?
Driving pressure is calculated by subtracting PEEP from plateau pressure.

20. What driving pressure value has been associated with increased mortality?
Driving pressures greater than approximately 15 cm H₂O have been associated with increased mortality.

21. What is auto-PEEP?
Auto-PEEP is unintended positive pressure remaining in the lungs at the end of expiration because the patient has not completely exhaled before the next breath begins.

22. What waveform finding suggests the presence of auto-PEEP?
Expiratory flow that fails to return to baseline before the next inspiration begins suggests incomplete exhalation and possible auto-PEEP.

23. What factors can contribute to auto-PEEP?
Auto-PEEP can result from a high respiratory rate, inadequate expiratory time, airway obstruction, bronchospasm, secretions, or obstructive lung disease.

24. What is patient-ventilator asynchrony?
Patient-ventilator asynchrony occurs when the patient’s respiratory effort does not appropriately match the ventilator’s triggering, flow delivery, inspiratory timing, cycling, or selected mode.

25. What should be done if a mechanically ventilated patient suddenly deteriorates and a ventilator or circuit malfunction is suspected?
The patient should be rapidly assessed and, when necessary, disconnected from the ventilator and manually ventilated with a resuscitation bag connected to oxygen while the ventilator and circuit are evaluated.

26. What ventilator settings should be verified during a routine ventilator check?
The clinician should verify the mode, respiratory rate, tidal volume or inspiratory pressure, FiO₂, PEEP, pressure support, inspiratory flow, inspiratory time, trigger sensitivity, and other mode-specific controls.

27. Why is it important to compare prescribed ventilator settings with actual ventilator settings?
This confirms that the ventilator is delivering the ordered support and helps identify programming errors or unintended changes.

28. Why should measured ventilator values be reviewed in addition to set values?
Measured values show what the patient is actually receiving and can reveal leaks, inadequate ventilation, abnormal respiratory mechanics, or changes in patient response.

29. What is exhaled tidal volume?
Exhaled tidal volume is the amount of gas measured as it returns from the patient during expiration.

30. What can a large difference between set or inspired tidal volume and exhaled tidal volume indicate?
It may indicate a circuit leak, cuff leak, disconnection, bronchopleural fistula, or another source of gas loss.

31. What is minute ventilation?
Minute ventilation is the total volume of gas moved in and out of the lungs in one minute.

32. What two variables determine minute ventilation?
Minute ventilation is determined by tidal volume and respiratory rate.

33. What can low minute ventilation indicate?
Low minute ventilation may indicate inadequate tidal volume, a low respiratory rate, reduced respiratory drive, sedation, apnea, leaks, or insufficient ventilatory support.

34. What can high minute ventilation indicate?
High minute ventilation may occur with tachypnea, pain, anxiety, fever, restlessness, hypoxemia, or increased respiratory drive.

35. Why should breath sounds be compared on both sides of the chest?
Comparing bilateral breath sounds helps identify asymmetry caused by airway obstruction, tube displacement, atelectasis, pneumothorax, or other unilateral lung problems.

36. What can sudden unilateral absent breath sounds suggest in an intubated patient?
They may suggest pneumothorax or unintended mainstem bronchus intubation.

37. What does dullness to percussion commonly suggest?
Dullness may occur with atelectasis, consolidation, or pleural effusion.

38. What is trigger sensitivity?
Trigger sensitivity determines how much patient effort is required to initiate an assisted ventilator breath.

39. What can happen if trigger sensitivity is set too insensitive?
The patient may need excessive effort to trigger the ventilator, increasing work of breathing and possibly causing missed breaths.

40. What can happen if trigger sensitivity is set too sensitive?
The ventilator may auto-trigger from circuit movement, leaks, condensate, or other disturbances.

41. What pressure-trigger sensitivity is commonly considered appropriate?
A pressure-trigger setting requiring approximately −1 to −2 cm H₂O of patient effort is commonly considered appropriate.

42. What is patient-ventilator synchrony?
Patient-ventilator synchrony occurs when the patient’s respiratory effort matches the ventilator’s triggering, flow delivery, inspiratory timing, and cycling.

43. What are the major types of patient-ventilator asynchrony?
Common types include trigger asynchrony, flow asynchrony, cycle asynchrony, and mode asynchrony.

44. What can cause flow asynchrony?
Flow asynchrony can occur when inspiratory flow does not adequately match the patient’s inspiratory demand.

45. What can cause trigger asynchrony?
Trigger asynchrony can result from inappropriate sensitivity, auto-PEEP, weak respiratory effort, leaks, or excessive effort required to initiate a breath.

46. What information can the pressure-time waveform provide?
The pressure-time waveform can help evaluate airway pressure, triggering, inspiratory pressure delivery, and some forms of patient-ventilator asynchrony.

47. What information can the flow-time waveform provide?
The flow-time waveform can help identify inspiratory flow problems, incomplete exhalation, air trapping, auto-PEEP, and synchronization issues.

48. What can a pressure-volume loop help assess?
A pressure-volume loop can help assess compliance, lung mechanics, and overdistention.

49. What does a beak-like appearance near the upper portion of a pressure-volume loop suggest?
It suggests possible alveolar overdistention.

50. What can a flow-volume loop help identify?
A flow-volume loop can help identify airway obstruction, leaks, bronchodilator response, and changes in expiratory flow.

51. Why are ventilator graphics useful during a ventilator check?
Ventilator graphics help identify problems with triggering, inspiratory flow, air trapping, leaks, lung mechanics, overdistention, and patient-ventilator asynchrony.

52. Why may ventilator waveforms need to be observed for more than a few breaths?
Some forms of patient-ventilator asynchrony are intermittent and may not be visible during only a brief observation period.

53. What is P0.1 or P100?
P0.1 is the negative airway pressure generated during the first 100 milliseconds of an inspiratory effort and is used as an indicator of respiratory drive.

54. What does a more negative P0.1 value generally indicate?
A more negative P0.1 value generally indicates greater respiratory drive and increased inspiratory effort.

55. What P0.1 range is generally considered acceptable during patient-triggered mechanical ventilation?
Values around −0.5 to −5 cm H₂O are generally considered acceptable.

56. Why may repeated P0.1 measurements be necessary?
Respiratory effort varies from breath to breath, so repeated measurements may better reflect the patient’s overall respiratory drive.

57. Why must ventilator alarms be individualized?
Alarm limits should be sensitive enough to detect clinically important changes without causing excessive false alarms.

58. What is the purpose of a high-pressure alarm?
A high-pressure alarm alerts clinicians when airway pressure rises above the preset limit and may indicate increased resistance, decreased compliance, obstruction, coughing, or asynchrony.

59. What is the purpose of a low-pressure alarm?
A low-pressure alarm helps detect loss of circuit pressure caused by leaks, loose connections, cuff leaks, or patient disconnection.

60. What can a low-PEEP alarm indicate?
A low-PEEP alarm may indicate circuit disconnection, airway leakage, cuff leakage, or malfunction of the PEEP system.

61. What can a low exhaled tidal-volume alarm indicate?
It may indicate a circuit leak, cuff leak, disconnection, bronchopleural fistula, shallow breathing, coughing, or patient-ventilator asynchrony.

62. What can activate a high minute ventilation alarm?
Tachypnea, anxiety, pain, fever, restlessness, or increased respiratory drive can activate a high minute ventilation alarm.

63. What can activate an apnea alarm?
Sedation, anesthesia, neurologic impairment, reduced respiratory drive, or an extremely low spontaneous respiratory rate can activate an apnea alarm.

64. How long is an apnea alarm delay commonly set?
An apnea alarm delay is commonly set at approximately 15 to 20 seconds, depending on the patient and ventilator.

65. Why should a ventilator alarm never simply be silenced?
The alarm may indicate a significant problem involving the patient, artificial airway, circuit, or ventilator that must be identified and corrected.

66. What can accumulated condensate in the breathing circuit cause?
Accumulated condensate can increase resistance, interfere with airflow, affect ventilator function, and contribute to alarm activation.

67. What can an obstructed heat-moisture exchanger cause?
An obstructed heat-moisture exchanger can increase airway resistance and contribute to elevated airway pressures.

68. Why should a manual resuscitation device be available at the bedside?
It provides an immediate means of ventilating the patient if the ventilator or breathing circuit fails or must be disconnected.

69. What does improvement during manual ventilation suggest when sudden deterioration occurs?
If the patient improves with manual ventilation, a ventilator or breathing-circuit problem becomes more likely.

70. Why is a test lung used during pre-use ventilator verification?
A test lung allows clinicians to confirm that the ventilator delivers the intended rate, tidal volume, pressure, oxygen concentration, timing, and other programmed parameters before connection to a patient.

71. What is the purpose of a ventilator power-on self-test?
The self-test checks basic ventilator operation, sensors, internal systems, and possible leaks before the ventilator is placed into clinical use.

72. What should be done if a ventilator fails its operational verification?
The ventilator should be removed from service and replaced with equipment that passes the required testing.

73. Why should the ventilator battery backup be checked?
Battery backup helps maintain ventilator operation during loss of electrical power and must have adequate charge to function safely.

74. Why should the oxygen analyzer be checked before ventilator use?
The oxygen analyzer helps verify that the delivered oxygen concentration matches the intended FiO₂.

75. Why are trends more useful than isolated ventilator values?
Trends can reveal gradual improvement or deterioration in airway resistance, compliance, ventilation, oxygenation, or equipment performance before a major problem occurs.

76. Why should the patient’s cardiac rhythm be considered during a ventilator check?
Changes in cardiac rhythm may indicate physiologic stress, hypoxemia, hemodynamic instability, or another problem affecting the patient’s response to mechanical ventilation.

77. Why should chest-wall symmetry be assessed during mechanical ventilation?
Asymmetrical chest-wall movement may suggest airway obstruction, endotracheal tube displacement, atelectasis, pneumothorax, or another unilateral pulmonary problem.

78. What can jugular venous distention suggest during a ventilator assessment?
Jugular venous distention may suggest increased intrathoracic pressure, right-sided cardiac strain, or other hemodynamic changes that require further evaluation.

79. Why is capillary refill assessed during the initial patient evaluation?
Capillary refill provides information about peripheral perfusion and can help identify circulatory compromise.

80. Why should the therapist communicate with a sedated or apparently unconscious patient?
Some patients may still be able to hear or understand what is happening, so explaining procedures remains appropriate even when they cannot respond.

81. What can retractions indicate in a mechanically ventilated patient?
Retractions suggest increased work of breathing and may indicate inadequate support, airway obstruction, or patient-ventilator asynchrony.

82. What can accessory muscle use indicate during a ventilator check?
Accessory muscle use suggests increased respiratory effort and may indicate that the patient’s ventilatory demand is not being fully met.

83. Why should the tracheal position be assessed?
Tracheal deviation can occur with serious conditions such as tension pneumothorax or severe atelectasis.

84. What may a sudden decrease in peak inspiratory pressure indicate?
A sudden decrease may indicate improved airway resistance, but it may also suggest a circuit leak, cuff leak, or patient disconnection.

85. Why should pressure changes never be interpreted in isolation?
Airway pressure changes can result from patient, airway, lung, circuit, or ventilator problems, so they must be correlated with the full clinical assessment.

86. Why is predicted body weight used when evaluating tidal volume?
Predicted body weight is used to determine whether tidal volume is within an appropriate lung-protective range rather than basing volume on actual body weight.

87. Why should mandatory and spontaneous tidal volumes sometimes be evaluated separately?
In modes that allow spontaneous breathing, the patient’s spontaneous tidal volumes may differ significantly from mandatory breaths and can provide important information about ventilatory adequacy.

88. What does mean airway pressure represent?
Mean airway pressure is the average pressure applied to the airways throughout the entire respiratory cycle.

89. Why is mean airway pressure clinically important?
Mean airway pressure influences oxygenation and reflects the overall pressure exposure of the respiratory system during mechanical ventilation.

90. What can a defective exhalation valve cause?
A defective exhalation valve can interfere with proper gas delivery and exhalation, causing abnormal tidal volumes, leaks, pressure problems, or ventilation failure.

91. Why should inspired and expired tidal volumes be compared?
Comparing them helps identify gas loss from leaks in the circuit, cuff, airway, or pulmonary system.

92. What can an expiratory pathway obstruction cause?
An expiratory obstruction can cause incomplete exhalation, gas trapping, increased pressure, rebreathing, and barotrauma.

93. Why is adequate expiratory time especially important in obstructive lung disease?
Patients with obstructive disease often require more time to exhale, and insufficient expiratory time can cause air trapping and auto-PEEP.

94. What can high respiratory rates contribute to during mechanical ventilation?
High respiratory rates can shorten expiratory time and promote incomplete exhalation, air trapping, and auto-PEEP.

95. Why should FiO₂ be verified during every ventilator check?
FiO₂ should be confirmed to ensure that the patient is receiving the intended oxygen concentration and that oxygen delivery is appropriate for the patient’s condition.

96. What information does pulse oximetry provide during a ventilator check?
Pulse oximetry provides continuous information about arterial oxygen saturation and helps identify changes in oxygenation.

97. What information does arterial blood gas analysis provide during mechanical ventilation?
Arterial blood gases provide information about pH, PaCO₂, and PaO₂, helping assess ventilation, acid-base status, and oxygenation.

98. What can capnography contribute to a ventilator assessment?
Capnography provides information about carbon dioxide elimination and may help identify changes in ventilation, airway position, perfusion, or circuit integrity.

99. Why should current ventilator findings be compared with previous assessments?
Comparison with previous findings helps detect trends such as worsening resistance, decreasing compliance, increasing oxygen requirements, or developing leaks before they become severe.

100. What is the overall goal of a complete ventilator check?
The overall goal is to ensure that the entire patient-ventilator system is providing safe, effective, synchronized, and lung-protective respiratory support.

Final Thoughts

A ventilator check is a patient-centered assessment that combines physical examination with evaluation of the artificial airway, ventilator settings, measured volumes, airway pressures, waveforms, alarms, humidification, circuit integrity, gas exchange, and patient-ventilator synchrony.

Correct ventilator settings alone do not guarantee effective respiratory support. The respiratory therapist must determine whether the patient is actually receiving adequate ventilation and oxygenation while remaining comfortable and protected from complications.

By assessing the entire patient-ventilator system and comparing current findings with previous trends, clinicians can identify problems early and maintain safer, more effective mechanical ventilation.