Mechanical ventilation nursing: complete guide for nursing students

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. Address with sedation adjustment or rate reduction, not by reducing the set rate alone (the set rate is a floor, not a ceiling on patient-triggered breaths).

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. PSV is typically added to support spontaneous breaths (SIMV + PS). SIMV remains used during gradual weaning when the rate is progressively reduced.

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.

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 targets 4–6 mL/kg IBW. The ARDSNet trial (ARMA, 2000) demonstrated a 22% relative reduction in mortality with 6 mL/kg IBW versus 12 mL/kg — the most impactful ventilator study in critical care. The permissive hypercapnia that results (PaCO2 may rise to 50–60 mmHg) 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 maintains SpO2 92–96% (or PaO2 55–80 mmHg). Prolonged FiO2 > 0.60 causes 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. The baseline physiologic PEEP is 5 cmH2O, which approximates the natural glottic resistance that maintains alveolar patency in the unintubated patient.

In ARDS, higher PEEP (8–20 cmH2O) is used to recruit collapsed alveoli and improve the P/F ratio. The optimal PEEP level in ARDS is individualized — too low allows derecruitment, too high causes barotrauma and hemodynamic compromise (PEEP reduces venous return and cardiac output at high levels). PEEP titration in ARDS follows ARDSNet FiO2/PEEP tables or is guided by transpulmonary pressure measurements.

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. PIP > 40–45 cmH2O indicates concern.

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

Driving pressure = Pplat – PEEP. Driving pressure < 15 cmH2O is associated with improved ARDS outcomes (Amato et al., NEJM 2015).

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) develops in 9–27% of mechanically ventilated patients and carries a mortality rate of 20–50% (CDC). VAP is defined as pneumonia occurring more than 48 hours after intubation. In the context of the pneumonia nursing reference, VAP represents the most preventable healthcare-associated infection in the ICU.

The VAP prevention bundle is evidence-based and should be implemented as a package — individual elements provide some benefit, but bundle compliance delivers the greatest reduction in VAP rates.

1. Head-of-bed (HOB) elevation: 30–45° Semi-recumbent positioning reduces microaspiration of oropharyngeal secretions and gastric contents around the ETT cuff. This is the single most important non-pharmacologic VAP prevention measure. Exceptions include spinal precautions and hemodynamic instability requiring supine positioning — document exceptions.

2. Oral care with chlorhexidine gluconate (CHG) 0.12% CHG oral rinse every 4–6 hours reduces oropharyngeal bacterial colonization — particularly gram-negative organisms that are the predominant VAP pathogens. Oral care includes tooth brushing, suctioning of subglottic secretions, and moistening of oral mucosa to prevent breakdown.

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. The ABCDE bundle (Awakening and Breathing Coordination) trial demonstrated that paired SAT + SBT reduced ICU LOS, ventilator days, and 1-year mortality. During SAT, assess for pain, anxiety, and delirium; restart sedation at 50% of the previous dose if patient is agitated or shows signs of respiratory compromise.

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
• Stress ulcer prophylaxis — controversial, currently recommended only for high-risk patients per latest PEPTIC trial data
• DVT prophylaxis — prevents PE and hemodynamic deterioration that would complicate weaning

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 (associated with 2–5× higher mortality); 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)

RSBI < 105 breaths/min/L predicts successful extubation with good sensitivity. RSBI ≥ 105 indicates rapid shallow breathing that predicts SBT failure.

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 was validated by Yang and Tobin (NEJM, 1991) and remains the most widely used single weaning predictor in clinical practice.

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 during SBT
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) — proactive HFNC post-extubation reduces reintubation risk in high-risk patients (Hernández et al., JAMA 2016)

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. Hyperoxygenate to FiO2 100% for 30 seconds before and after
2. Insert suction catheter without suction applied until resistance is met, then withdraw 1–2 cm
3. Apply suction (80–120 mmHg) while rotating and withdrawing over no more than 10–15 seconds
4. Allow recovery between passes (SpO2 must return to baseline); limit to 3 passes maximum
5. Reassess breath sounds, SpO2, and hemodynamics after

Closed suction systems (inline suction) allow suctioning without disconnecting the ventilator circuit — preferred for ARDS patients (prevents derecruitment) and for infection control.

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 — PaCO2 may reach 50–60 mmHg as the trade-off for avoiding volutrauma and barotrauma with low Vt. The pH is more important than the PaCO2; providers generally accept pH ≥ 7.25.

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. HOB elevation 30–45° is the single most important VAP prevention intervention. Flat positioning allows microaspiration of gastric contents around the ETT cuff.

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

8. RSBI < 105 predicts successful extubation; ≥ 105 predicts failure. Calculate it: RSBI = RR ÷ Vt (in liters).

9. In ARDS, accept permissive hypercapnia — prioritize Pplat ≤ 30 cmH2O over normalizing PaCO2. The target is pH ≥ 7.25, not a normal PaCO2.

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 SAT + SBT protocol (ABCDE bundle) is the standard of care.

15. Post-extubation stridor is laryngeal edema. First-line treatment: racemic epinephrine nebulization. Have reintubation equipment at the bedside.

16. COPD patients may have a chronically elevated PaCO2 baseline. Do not over-ventilate to a “normal” PaCO2 — you may abolish their hypoxic drive and cause respiratory alkalosis.

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 intervention is to reduce RR or Vt to decrease minute ventilation. 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 needle decompression (2nd intercostal space, midclavicular line) — the provider must be notified immediately. 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.