Mechanical ventilation nursing: DOPE mnemonic, RSBI, and NCLEX guide

Mechanical ventilation is the cornerstone of life support in the ICU, and it is one of the most heavily tested topics in critical care nursing. A ventilated patient cannot communicate distress, cannot protect their airway without skilled nursing assessment, and cannot safely wean without vigilant clinical judgment. Understanding the ventilator – what each mode does, what each setting means, what each alarm signals, and how to support a patient through liberation – is not optional knowledge for an ICU nurse. It is the foundation of the role.

This reference covers everything nursing students need to know: ventilator modes, key settings, alarm management, VAP prevention, weaning criteria, extubation, tracheostomy care, ABG interpretation in ventilated patients, and a full NCLEX tips section. Pair it with the ARDS nursing reference for lung-protective ventilation strategy, the ABG interpretation guide for blood gas management, and the pneumonia nursing reference for VAP context. Patients requiring mechanical ventilation are often critically ill from sepsis or other systemic conditions covered in the ICU critical care nursing reference.

Indications for mechanical ventilation

Mechanical ventilation is initiated when a patient cannot maintain adequate gas exchange or airway patency independently. The major indications fall into four categories:

Ventilatory failure – rising PaCO2 with respiratory muscle fatigue, as seen in severe COPD exacerbations, neuromuscular disorders (Guillain-Barré, myasthenia gravis), or drug-induced respiratory depression. The hallmark is hypercapnia with respiratory acidosis that the patient cannot reverse.

Hypoxemic respiratory failure – refractory hypoxemia (PaO2 < 60 mmHg or SpO2 < 90% despite high-flow supplemental oxygen), most commonly from pneumonia, ARDS, or pulmonary edema.

Airway protection – a GCS ≤ 8, loss of gag reflex, or massive aspiration risk. An unconscious patient cannot protect the airway from secretions and gastric contents; intubation secures the airway before respiratory failure occurs.

Peri-operative support – planned post-operative mechanical ventilation following cardiac surgery, thoracic surgery, or prolonged procedures.

Ventilator modes – detailed comparison

The mode determines who controls the breath: the ventilator, the patient, or both. Each mode allocates respiratory work differently and carries distinct clinical applications.

AC – assist-control (volume control)

Assist-Control is the most common mode for newly intubated, critically ill patients. The ventilator delivers a full, preset tidal volume with every breath – whether the patient triggers the breath or the machine delivers it at the set rate. Every breath is fully supported.

How it works: A backup rate is set (e.g., 14 breaths/min). If the patient triggers a breath, the ventilator delivers the full Vt. If the patient makes no effort within the cycle window, the machine delivers a mandatory breath at the set rate. The patient always receives at least the set rate, and every breath – spontaneous or mandatory – receives full volume support.

Clinical use: Initial management of respiratory failure, post-operative intubation, heavily sedated or paralyzed patients, patients with no respiratory drive.

Key risk: Respiratory alkalosis. If an anxious or tachypneic patient is breathing at 30 breaths/min and every breath gets a full Vt, minute ventilation rises sharply and PaCO2 drops. Lowering the set rate alone will not fix this, because the set rate is a floor, not a ceiling on patient-triggered breaths. Look for the driver (pain, anxiety, fever, hypoxemia, metabolic acidosis) and treat it; the provider may reduce Vt or change the mode.

SIMV – synchronized intermittent mandatory ventilation

SIMV delivers a set number of mandatory full-volume breaths per minute (synchronized with the patient’s own efforts) while allowing spontaneous breathing between those breaths. Spontaneous breaths above the mandatory rate are not augmented unless pressure support is added.

How it works: If set at 10 breaths/min, the ventilator delivers 10 full Vt breaths. Any spontaneous breath the patient takes between mandatory breaths is unsupported – the patient moves whatever volume their own muscles generate.

Clinical use: Formerly popular as a weaning mode; now less favored because unsupported spontaneous breaths increase work of breathing and can cause respiratory muscle fatigue, and in a landmark comparison of four weaning methods, a once-daily spontaneous breathing trial led to extubation about three times faster than gradual SIMV reduction (Esteban et al., 1995). PSV is typically added to support spontaneous breaths (SIMV + PS).

Key risk: Increased work of breathing if spontaneous breaths are unsupported. This can paradoxically prolong ventilator dependence.

PSV – pressure support ventilation

In PSV, the ventilator provides a set level of inspiratory pressure support every time the patient initiates a breath. The patient controls rate, inspiratory time, and (to a significant degree) tidal volume. There is no mandatory backup rate in pure PSV.

How it works: When the patient begins inhaling and creates negative airway pressure or detectable flow, the ventilator augments the breath with the preset pressure (e.g., 10 cmH2O PS). The breath ends when inspiratory flow drops below a threshold (flow cycling). The patient’s own respiratory muscles do the rest of the work.

Clinical use: Weaning and liberation – progressively reducing PS from 10–15 cmH2O toward 5–8 cmH2O and ultimately 0 (CPAP alone) evaluates the patient’s readiness for extubation. Also used in SIMV + PS to support spontaneous breaths.

Key risk: Apnea if the patient’s respiratory drive fails – there is no backup rate in pure PSV. An apnea alarm must be enabled. PSV is not appropriate for patients with unreliable respiratory drive.

CPAP – continuous positive airway pressure (on the ventilator)

On a ventilator circuit, CPAP maintains a constant positive pressure throughout the entire respiratory cycle. The ventilator provides no additional mandatory breaths and no inspiratory augmentation – the patient breathes spontaneously against a continuous positive baseline pressure.

How it works: CPAP on the ventilator is functionally equivalent to maintaining PEEP with no additional support. The pressure holds alveoli open during both inspiration and expiration, improving oxygenation and reducing work of breathing against collapsed airways.

Clinical use: Spontaneous breathing trial (SBT) – placing the patient on CPAP 5 cmH2O (with or without minimal PS of 5–8 cmH2O) for 30–120 minutes assesses whether the patient can sustain independent breathing before extubation. For the first SBT in patients ventilated more than 24 hours, the ACCP/ATS 2017 guideline suggests adding inspiratory pressure augmentation (5–8 cmH2O) rather than using a T-piece or CPAP alone.

Distinction from non-invasive CPAP: Ventilator CPAP requires an ETT or tracheostomy. Non-invasive CPAP uses a mask and is a distinct therapy.

Key ventilator settings

Tidal volume (Vt)

Tidal volume is the volume of gas delivered with each breath. In most clinical adults, initial Vt is set at 6–8 mL/kg ideal body weight (IBW), not actual body weight. Using actual body weight in obese patients would deliver dangerously large tidal volumes because lung size correlates with height, not weight.

In ARDS, lung-protective ventilation uses 4–8 mL/kg IBW with plateau pressure below 30 cmH2O, a strong recommendation in the 2017 ATS/ESICM/SCCM guideline. In practice the starting point is 6 mL/kg. The ARDSNet trial (ARMA, 2000) found mortality of 31.0% with about 6 mL/kg versus 39.8% with about 12 mL/kg – a 22% relative reduction and one of the most influential ventilator studies in critical care. The resulting permissive hypercapnia is accepted to prevent ventilator-induced lung injury (VILI).

Calculating IBW:

• Males: 50 + 2.3 × (height in inches – 60)
• Females: 45.5 + 2.3 × (height in inches – 60)

Respiratory rate (RR)

The set RR establishes the backup rate – the minimum number of breaths per minute the ventilator guarantees. Typical initial settings: 12–16 breaths/min. In ARDS with low Vt, the rate may be increased to 20–30 to maintain adequate minute ventilation (MV = Vt × RR). Excessively high rates risk intrinsic PEEP (auto-PEEP) due to inadequate exhalation time.

FiO2 (fraction of inspired oxygen)

FiO2 represents the percentage of oxygen in the delivered gas, ranging from 0.21 (room air) to 1.0 (100% oxygen). The goal is the lowest FiO2 that meets the ordered oxygen target. A 2018 BMJ guideline on acutely ill adults recommends against keeping SpO2 above 96%, because liberal oxygen increased mortality. The ARDSNet protocol targets PaO2 55–80 mmHg or SpO2 88–95%. Prolonged FiO2 > 0.60 is associated with oxygen toxicity – free radical-mediated injury to type I and type II pneumocytes. In clinical practice, FiO2 is weaned first before PEEP once oxygenation improves, because PEEP reduction carries the risk of alveolar derecruitment.

PEEP (positive end-expiratory pressure)

PEEP maintains positive airway pressure at end-expiration, preventing alveolar collapse (derecruitment) between breaths. Most adults are started at 5 cmH2O.

In moderate to severe ARDS, the 2024 ATS guideline suggests higher PEEP without prolonged lung recruitment maneuvers (conditional recommendation), and recommends against prolonged recruitment maneuvers (strong recommendation). The optimal PEEP level is individualized – too low allows derecruitment, too high causes overdistension and hemodynamic compromise (PEEP reduces venous return and cardiac output at high levels). Titration commonly follows the ARDSNet FiO2/PEEP tables.

Other ARDS therapies the nurse supports

Current ATS guidance for ARDS (2017, updated 2024) also covers:

• Prone positioning for more than 12 hours a day in severe ARDS (strong recommendation). In the PROSEVA trial, sessions of at least 16 hours cut 28-day mortality from 32.8% to 16.0% (Guérin et al., 2013). See the prone positioning guide.
• Neuromuscular blockers in early severe ARDS (conditional). ACURASYS (Papazian et al., 2010) found lower adjusted 90-day mortality with 48 hours of cisatracurium, but the larger ROSE trial (2019), with lighter sedation in the control arm, found no difference (42.5% vs 42.8%).
• Corticosteroids (conditional recommendation, 2024).
• Venovenous ECMO for selected patients with severe ARDS (conditional). In EOLIA, 60-day mortality was 35% with ECMO versus 46% with conventional care, a difference that did not reach statistical significance (Combes et al., 2018).

ARDS itself was redefined in 2024. The new global definition keeps the Berlin framework but also allows diagnosis in patients on high-flow nasal oxygen at 30 L/min or more, and allows SpO2/FiO2 in place of an arterial blood gas (Matthay et al., 2024).

I:E ratio

The inspiratory-to-expiratory ratio is normally 1:2 – exhalation takes twice as long as inhalation, allowing full CO2 clearance. In obstructive disease (asthma, COPD), a longer expiratory time (1:3 or 1:4) prevents air trapping and auto-PEEP. Inverse ratio ventilation (I:E of 1:1 or 2:1) is occasionally used in severe ARDS to improve oxygenation by prolonging alveolar recruitment time, though it requires deep sedation and paralysis and is not standard.

Peak inspiratory pressure (PIP) and plateau pressure (Pplat)

PIP is the maximum pressure generated during the breath – it reflects both airway resistance and lung/chest wall compliance. A sudden rise in PIP is the trigger to assess the patient and the circuit.

Plateau pressure (Pplat) is measured at end-inspiration during a pause (no airflow) – it reflects static lung compliance, excluding airway resistance. Pplat below 30 cmH2O is the lung-protective threshold. Pplat at or above 30 cmH2O indicates overdistension and increased VILI risk.

Driving pressure = Pplat – PEEP. In a pooled analysis of nine ARDS trials, driving pressure was the ventilation variable most strongly associated with survival (Amato et al., NEJM 2015); about 15 cmH2O is the commonly cited upper limit.

Interpreting the PIP–Pplat relationship:

• High PIP, normal Pplat → elevated airway resistance (secretions, bronchospasm, kinked ETT)
• High PIP, high Pplat → reduced lung compliance (ARDS, pneumothorax, tension pneumothorax, pulmonary edema)

Ventilator alarms – causes and nursing response

When an alarm sounds, the first priority is always patient assessment – never silence an alarm without first establishing that the patient is safe. The mnemonic DOPE covers the most critical high-pressure causes: Displacement, Obstruction, Pneumothorax, Equipment failure.

BVM readiness is non-negotiable. A bag-valve-mask must be at the bedside of every intubated patient, 100% of the time, charged and ready. If the ventilator fails for any reason – circuit disconnection, machine malfunction, power failure – the nurse manually ventilates.

VAP prevention bundle

Ventilator-associated pneumonia (VAP) is pneumonia that develops more than 48 hours after intubation. Surveillance rates are hard to compare because the diagnosis is subjective, but the 2022 SHEA/IDSA/APIC compendium notes that 5–10% of ventilated patients are still treated for VAP and estimates its attributable mortality at about 10% (Klompas et al., 2022). See the pneumonia nursing reference for diagnosis and treatment.

The 2022 compendium ranks its recommendations. Essential practices for adults include avoiding intubation where high-flow nasal oxygen or noninvasive ventilation is safe, minimizing sedation, a ventilator liberation protocol with daily awakening and breathing trials, early exercise and mobilization, HOB elevation, daily toothbrushing without chlorhexidine, early enteral nutrition, and changing the ventilator circuit only when it is visibly soiled or malfunctioning. The elements that shorten ventilation (less sedation, earlier liberation) have the strongest evidence.

1. Head-of-bed (HOB) elevation: 30–45° Semi-recumbent positioning reduces microaspiration of oropharyngeal secretions and gastric contents around the ETT cuff. SHEA keeps it as an essential practice because it is simple and low-risk, but rates the evidence LOW: a meta-analysis of 8 small trials found fewer VAP diagnoses and no difference in ventilator days or mortality. Exceptions include spinal precautions and hemodynamic instability requiring supine positioning – document exceptions.

2. Oral care with a toothbrush – NOT routine chlorhexidine

This recommendation reversed. The SHEA/IDSA/APIC 2022 update no longer endorses routine 0.12% chlorhexidine (CHG) oral rinse for ventilated adults: when meta-analyses were restricted to double-blinded trials, the apparent VAP reduction disappeared, and pooled data showed a signal toward increased mortality. Many units have since de-implemented CHG from their VAP bundles. What the 2022 update does recommend is regular oral care with a toothbrush, plus suctioning of subglottic secretions and moistening of the oral mucosa to prevent breakdown. Follow your own institution’s current bundle, and expect older NCLEX question banks and textbooks to still list CHG.

3. ETT cuff pressure: 20–30 cmH2O The ETT cuff creates a seal that prevents aspiration of oropharyngeal secretions into the lower airway. Cuff pressure below 20 cmH2O allows microaspiration around the cuff; above 30 cmH2O risks tracheal mucosal ischemia. Check cuff pressure every 4–8 hours with a cuff pressure manometer – never estimate by feel.

4. Daily sedation vacation (SAT) Interrupting sedation infusions daily allows nurses to assess the patient’s neurologic status and reduce sedative accumulation. In the Awakening and Breathing Controlled (ABC) trial, pairing a daily SAT with a daily SBT gave patients 3.1 more days breathing without assistance (14.7 vs 11.6 days), shortened median ICU stay from 12.9 to 9.1 days, and lowered 1-year mortality (hazard ratio 0.68) (Girard et al., 2008). That trial later became the “A” and “B” of the ICU Liberation (ABCDEF) bundle. During SAT, assess for pain, anxiety, and delirium; in the ABC protocol, sedation that had to be restarted was resumed at half the previous dose.

5. Daily SBT readiness assessment Every morning, screen for weaning readiness (see weaning section). Prolonged ventilation is independently associated with increased VAP risk, ICU-acquired weakness, and delirium. Every unnecessary ventilator day increases risk.

Additional bundle elements (per institution):

• Subglottic secretion drainage (SSD) ETTs – continuously aspirate secretions pooling above the cuff
• Early enteral nutrition, and changing the ventilator circuit only when visibly soiled or malfunctioning (both SHEA essential practices)

Often bundled, but not VAP prevention: stress ulcer prophylaxis and DVT prophylaxis are routine ICU orders, and SHEA 2022 lists stress ulcer prophylaxis among measures generally not recommended for VAP prevention. Stress ulcer prophylaxis is given to prevent GI bleeding. In the REVISE trial of 4,821 ventilated adults, pantoprazole cut clinically important upper GI bleeding from 3.5% to 1.0% with no significant effect on 90-day mortality (29.1% vs 30.9%) (Cook et al., 2024).

Weaning and liberation criteria

Liberation from mechanical ventilation requires confirming that the original reason for intubation has resolved or improved sufficiently for the patient to sustain independent breathing. Premature extubation leads to reintubation: in one cohort, hospital mortality was 43% in reintubated patients versus 12% in those successfully extubated (Epstein et al., 1997); delayed extubation prolongs exposure to VAP, ICU-acquired weakness, and sedation complications.

Daily weaning screen – readiness criteria

Assess all of the following each morning:

If the patient passes the screen, proceed to a spontaneous breathing trial.

Spontaneous breathing trial (SBT)

The SBT tests whether the patient can breathe independently for 30–120 minutes. Most SBTs use one of two methods:

• T-piece trial: ETT is disconnected from the ventilator and connected to a humidified oxygen source. Maximum respiratory muscle challenge.
• CPAP 5 cmH2O ± PS 5–8 cmH2O: Maintains airway pressure and provides minimal inspiratory support. More comfortable; widely used.

Monitor during SBT for failure signs (ABCS mnemonic):

• Agitation or accessory muscle use
• Bradycardia, tachycardia, or dysrhythmia
• Confusion, decreasing consciousness, or SpO2 < 90%
• Sweating, paradoxical breathing (chest/abdomen moving out of phase), or RR > 35 breaths/min

If the patient tolerates the SBT for 30–120 minutes without failure signs, proceed to extubation assessment.

RSBI (rapid shallow breathing index)

RSBI = respiratory rate (f) ÷ tidal volume in liters (Vt)

Yang and Tobin measured the RSBI during one minute of unassisted breathing, before the weaning trial. A value below 105 breaths/min/L predicted a successful weaning trial with high sensitivity (0.97) but low specificity (0.64); a value of 105 or more indicates rapid shallow breathing that predicts failure. A low RSBI therefore makes the patient a good candidate for an SBT, and the SBT itself is the test.

Example: RR 22, Vt 0.45 L → RSBI = 22 ÷ 0.45 = 49 (favorable) Example: RR 30, Vt 0.25 L → RSBI = 30 ÷ 0.25 = 120 (failure predicted)

The RSBI (Yang and Tobin, NEJM 1991) remains the most widely used single weaning predictor, but the ACCP/ATS 2017 liberation guidelines build the decision around a protocolized daily SBT rather than any single index.

Extubation criteria and post-extubation monitoring

Extubation criteria

Before extubating, confirm all of the following:

1. Passed SBT for 30–120 minutes
2. Patient can follow commands (raise two fingers, stick out tongue)
3. Adequate cough and gag reflex – assess cough strength during suctioning
4. RSBI < 105 on the readiness screen (supportive, not decisive)
5. Airway secretions are manageable (not copious)
6. Equipment and team at bedside: provider, respiratory therapist, suction, oxygen, reintubation equipment

Extubation procedure

1. Suction oropharynx above cuff thoroughly
2. Deflate ETT cuff completely
3. On inspiration (positive airway pressure), remove ETT in one smooth motion
4. Immediately apply supplemental oxygen (high-flow nasal cannula, Venturi mask, or non-rebreather per order)
5. Reassure and coach the patient – deep breaths, cough if able

Post-extubation monitoring (first 2 hours are highest risk)

• SpO2 every 15 minutes × 2 hours, then per unit protocol
• Respiratory rate and work of breathing – note stridor, retractions, paradoxical breathing
• Voice quality – new hoarseness indicates vocal cord injury from intubation
• Secretion management – suction oropharynx as needed; encourage coughing
• Post-extubation stridor – may respond to racemic epinephrine nebulization (laryngeal edema); have reintubation equipment at bedside
• High-flow nasal cannula (HFNC) – in patients at low risk of reintubation, HFNC after extubation cut 72-hour reintubation from 12.2% to 4.9% compared with conventional oxygen (Hernández et al., JAMA 2016;315). In high-risk patients, HFNC was noninferior to noninvasive ventilation (reintubation 22.8% vs 19.1%) (Hernández et al., JAMA 2016;316)

Reintubation criteria: SpO2 < 90% despite maximal non-invasive support, severe respiratory distress or fatigue, loss of airway protective reflexes, or hemodynamic deterioration attributable to respiratory failure.

Tracheostomy nursing care

A tracheostomy is placed when prolonged mechanical ventilation is anticipated (typically > 10–14 days), when upper airway obstruction prevents orotracheal intubation, or to facilitate weaning in patients with high secretion burden or inadequate cough. Compared to prolonged oral intubation, tracheostomy improves patient comfort, facilitates oral feeding and communication, and reduces laryngeal injury.

Suctioning

Suction only when indicated – the presence of secretions audible on auscultation or visible in the circuit, a decrease in SpO2, or patient distress. Routine timed suctioning is not evidence-based and traumatizes the tracheal mucosa.

Technique for open suctioning:

1. Preoxygenate if the patient has previously desaturated with suctioning (AARC 2010 suggests considering preoxygenation in that case, rather than routinely)
2. Choose a catheter that occludes less than 50% of the tube’s inner lumen in adults
3. Insert without suction applied; shallow suction (to the end of the artificial airway) is suggested over deep suction that advances until resistance is met
4. Apply suction while withdrawing, keeping each suctioning event under 15 seconds; do not routinely instill normal saline
5. Allow SpO2 to return to baseline between passes, then reassess breath sounds, SpO2, and hemodynamics

Closed suction systems (inline suction) allow suctioning without disconnecting the ventilator circuit. AARC 2010 suggests them for adults on high FiO2 or PEEP or at risk of derecruitment, such as patients with ARDS. SHEA 2022 found they do not lower VAP rates, so their case rests on preventing derecruitment.

Cuff management

Maintain cuff pressure at 20–30 cmH2O using a cuff pressure manometer. Check every 4–8 hours and after any repositioning. A cuff pressure below 20 cmH2O allows aspiration of subglottic secretions; above 30 cmH2O causes tracheal ischemia, necrosis, and ultimately tracheomalacia.

For patients who are tolerating a speaking valve trial or cuff-down periods, completely deflate the cuff and monitor for aspiration carefully.

Inner cannula care

Most tracheostomy tubes have a removable inner cannula. Remove and clean the inner cannula every 8 hours (or per unit protocol) and whenever secretions are visible. Clean with normal saline or sterile water, inspect for cracks, and reinsert securely. A blocked inner cannula is a rapid-onset airway emergency – if resistance to ventilation suddenly increases and the patient is a tracheostomy patient, removing and replacing the inner cannula is the first intervention.

Stoma care

Clean the peristomal skin with normal saline every 8 hours and as needed. Inspect for erythema, breakdown, or signs of infection. Change tracheostomy ties or securement device when soiled or loosened, with a second nurse stabilizing the tracheostomy tube during the change – premature decannulation is a preventable emergency. Keep a same-size and one-size-smaller tracheostomy tube and dilators at the bedside for emergency replacement.

Speaking valves (Passy-Muir valve)

The Passy-Muir valve (PMV) is a one-way speaking valve that opens on inspiration and closes on expiration, directing airflow past the vocal cords. The cuff must be completely deflated before applying a PMV – if the cuff is inflated with the PMV in place, the patient cannot exhale and will asphyxiate. Confirm cuff deflation before every PMV application, without exception.

ABG interpretation in the context of ventilator management

Arterial blood gas (ABG) results directly guide ventilator adjustments. For full ABG interpretation methodology, see the ABG interpretation guide. In ventilated patients, the key relationships are:

PaCO2 is controlled by minute ventilation (MV = Vt × RR)

• PaCO2 high (respiratory acidosis) → increase RR or Vt (increase minute ventilation)
• PaCO2 low (respiratory alkalosis) → decrease RR or Vt (decrease minute ventilation)

PaO2 is controlled by FiO2 and PEEP

• PaO2 low → increase FiO2 first; increase PEEP if FiO2 already ≥ 0.60
• PaO2 acceptable → wean FiO2 before weaning PEEP

Typical ABG interpretation scenarios in ventilated patients:

In ARDS with lung-protective ventilation, permissive hypercapnia is accepted as the trade-off for avoiding volutrauma and barotrauma with low Vt. The ARDSNet protocol aims for pH 7.30–7.45: when pH falls below 7.30, the rate is raised first (to a maximum of 35/min), and only below pH 7.15 may Vt be increased above the target or bicarbonate considered.

Differentiation table: MV vs CPAP/BiPAP vs HFNC

NCLEX tips

1. Tidal volume is based on IBW, not actual body weight. An obese patient (150 kg, 5’10”) has an IBW of ~76 kg – Vt is set at 6–8 mL/kg × 76 kg = 456–608 mL, not 900–1,200 mL.

2. First response to any ventilator alarm: assess the patient. Never silence first, assess second. The patient is always the priority.

3. BVM must be at the bedside of every intubated patient. If the ventilator fails, the nurse manually ventilates. This is non-negotiable.

4. High pressure alarm + absent unilateral breath sounds = tension pneumothorax until proven otherwise. Needle decompression is a life-saving emergency intervention. Notify provider immediately.

5. Low pressure alarm = disconnection or cuff leak first. Check all circuit connections and cuff pressure before anything else.

6. Keep the HOB at 30–45° unless contraindicated. It is an essential, low-risk VAP measure that limits microaspiration around the ETT cuff, but SHEA rates its evidence low. Minimizing sedation and running daily awakening and breathing trials have stronger evidence because they shorten time on the ventilator.

7. Pplat of 30 cmH2O or more requires intervention. Notify provider; the patient is at risk for barotrauma and VILI. Do not simply document and move on.

8. RSBI < 105 predicts a successful weaning trial; ≥ 105 predicts failure. Calculate it: RSBI = RR ÷ Vt (in liters). It is a screening tool; the SBT decides readiness.

9. In ARDS, accept permissive hypercapnia – prioritize Pplat below 30 cmH2O over normalizing PaCO2. The ARDSNet pH goal is 7.30–7.45, reached by raising the rate before giving up on low Vt; a normal PaCO2 is not the target.

10. Cuff pressure target is 20–30 cmH2O for both ETTs and tracheostomies. Below 20 = aspiration risk; above 30 = ischemia risk.

11. The Passy-Muir valve requires a completely deflated cuff before application. Failure to deflate the cuff is a fatal error.

12. PSV has no backup rate – apnea alarm must be enabled. If the patient’s drive fails, the ventilator provides no rescue breath.

13. Weaning FiO2 before PEEP when oxygenation improves. Removing PEEP prematurely causes alveolar derecruitment and acute desaturation.

14. Daily sedation vacation paired with daily SBT reduces ventilator days. The ABC trial (Girard et al., 2008) showed this paired protocol shortened ventilation and ICU stay and improved 1-year survival; it forms the “A” and “B” of the ABCDEF bundle.

15. Post-extubation stridor usually signals laryngeal edema. Racemic epinephrine nebulization is a common first treatment per provider order. Have reintubation equipment at the bedside.

16. COPD patients may have a chronically elevated PaCO2 baseline. Do not over-ventilate to a “normal” PaCO2. Their kidneys have retained bicarbonate to compensate, so a rapid drop in PaCO2 causes metabolic alkalosis, and the kidneys then excrete that bicarbonate, which makes weaning harder when the patient must breathe on their own again.

17. For medications administered via MDI on the ventilator: A spacer is required for metered-dose inhalers in the ventilator circuit. Without a spacer, the medication impacts the circuit walls and only a fraction reaches the lungs. See the respiratory medications nursing reference for bronchodilator delivery via in-line MDI with spacer.

Practice questions

Question 1. A nurse is caring for a patient on AC ventilation at RR 14, Vt 500 mL, FiO2 0.45, PEEP 5. ABG shows: pH 7.51, PaCO2 28, PaO2 90, HCO3 22. What is the priority nursing action?

A. Increase FiO2 to 0.60
B. Notify provider of respiratory alkalosis; anticipate RR or Vt reduction
C. Increase PEEP to 8 cmH2O
D. Suction the patient for secretions

Answer: B. The ABG shows respiratory alkalosis (pH 7.51, PaCO2 28). The patient is over-ventilated on AC mode – likely breathing faster than the set rate and getting full Vt support with each breath, driving PaCO2 down. The fix is to reduce minute ventilation: if the patient is triggering above the set rate, lowering the set rate alone will not help, so look for the cause of the tachypnea (pain, anxiety, fever) and expect the provider to lower Vt or adjust sedation. FiO2 and PEEP changes address oxygenation, not pH/CO2.

Question 2. During an SBT, a previously stable patient develops RR 38, SpO2 89%, diaphoresis, and accessory muscle use after 20 minutes. What is the appropriate response?

A. Continue the SBT – 30 minutes is required for a valid trial
B. Place patient back on AC ventilation and notify provider of SBT failure
C. Increase PEEP by 5 cmH2O
D. Administer a sedative to reduce agitation

Answer: B. The patient is showing multiple SBT failure criteria: tachypnea > 35, hypoxia, diaphoresis (sympathetic activation), and accessory muscle use. Return to full ventilatory support; do not continue an SBT in a deteriorating patient. Increasing PEEP mid-SBT is not the appropriate response to SBT failure.

Question 3. A high-pressure alarm sounds on a ventilated patient. The nurse assesses and finds decreased breath sounds on the left, tracheal deviation to the right, and hypotension. What is the priority action?

A. Suction the ETT
B. Administer a bronchodilator
C. Immediately notify the provider – tension pneumothorax suspected
D. Reposition the patient’s ETT

Answer: C. Decreased unilateral breath sounds + tracheal deviation + hypotension + high-pressure alarm is the classic presentation of tension pneumothorax. This is a life-threatening emergency requiring immediate decompression – the provider must be notified immediately. In adults, ATLS (10th edition) places needle decompression at the 4th or 5th intercostal space just anterior to the midaxillary line, because a standard catheter often fails to reach the pleural space at the traditional 2nd intercostal space, midclavicular line. Suctioning and bronchodilators are not indicated; repositioning the ETT does not address the problem.

Mechanical ventilation is among the most technically demanding and clinically critical aspects of ICU nursing. Mastery of modes, settings, alarm interpretation, and weaning principles is built at the bedside – but a strong conceptual foundation from this reference will prepare nursing students to approach ventilated patients with confidence rather than anxiety. For further depth on the conditions most commonly leading to mechanical ventilation, work through the ARDS nursing reference, sepsis nursing guide, and ABG interpretation guide as companion resources.

References

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