13.2 ARDS, ICU and Critical Care Safety
Key Takeaways
ARDS/ALI is acute hypoxaemic respiratory failure with diffuse alveolar injury; physiotherapy supports medical lung-protective care, positioning, and carefully selected early mobility—never freelances ventilator settings.
ICU safety starts with environment scan: airway, lines, drains, infusions, monitoring leads, and team communication before any touch or transfer.
Entry-level ventilatory concepts include that mechanical ventilation supports gas exchange and work of breathing; mobilisation of ventilated patients requires unit protocol, adequate staffing, and stability criteria.
Know when NOT to mobilise: unstable haemodynamics, uncontrolled arrhythmias, acute neurological deterioration, insecure airway, active bleeding, or explicit medical hold—document and reassess.
Oxygen delivery devices range from low-flow nasal cannula to high-flow and non-invasive or invasive ventilation; titrate only within prescribed targets and escalate when targets fail.
Quick Answer: ICU excellence starts with a bedspace scan (airway, lines, drains, infusions, orders) and team communication—never freelanced ventilator changes. ARDS is medically led lung-protective care; physio contributes positioning, secondary-complication prevention, and criteria-based early mobility. Know hard stops: unstable shock/escalating vasopressors, insecure airway, active bleeding, explicit bed-rest orders. Restore SpO2/position and escalate if targets fail.
Intensive care unit (ICU) vignettes on the APC Written Assessment check whether you can work safely in a high-acuity environment, recognise ARDS-type critical respiratory failure at a conceptual level, respect lines and life-support equipment, and decide when mobilisation is appropriate versus dangerous. You are not expected to independently set ventilator modes or manage continuous renal replacement therapy. You are expected to scan the bedspace, communicate with the multidisciplinary team, protect the airway and devices, and contribute sensible respiratory and mobility care within protocol.
ARDS and ALI: Concepts for Physiotherapists
Acute respiratory distress syndrome (ARDS) is a syndrome of acute hypoxaemic respiratory failure with bilateral opacities not fully explained by cardiac failure or fluid overload alone, occurring within a defined timeframe after a known clinical insult (sepsis, pneumonia, aspiration, trauma, pancreatitis, and others). Older exam materials may still mention acute lung injury (ALI) as a related milder hypoxaemia concept; clinically you will mostly hear ARDS severity tiers (mild/moderate/severe) based on oxygenation indices used by the medical team.
Pathophysiology themes (entry level):
- Diffuse alveolar-capillary injury → protein-rich oedema, surfactant dysfunction, reduced compliance
- Severe V/Q mismatch and shunt → refractory hypoxaemia
- Need for lung-protective ventilation strategies led by intensive care medicine (low tidal volume themes, plateau pressure limits, careful PEEP)—physiotherapists support but do not own these settings
Physiotherapy roles in ARDS-spectrum care typically include:
- Positioning (including awareness of prone positioning protocols run by the ICU team)
- Secretion management only when indicated and safe (many ARDS lungs are not “full of loose sputum” early on)
- Prevention of secondary complications: joint stiffness, muscle weakness (ICU-acquired weakness), pressure areas, deconditioning
- Participation in early mobility programs when stability criteria are met
- Family communication within scope and realistic goal-setting during prolonged ICU stays
Avoid the trap of treating ARDS as “just pneumonia needing harder percussion.” Aggressive airway clearance without secretion load can increase oxygen demand and distress.
ICU Environment Scan: Your First Skill
Before hands-on care, perform a systematic scan:
- Airway: endotracheal tube (ETT) or tracheostomy position and security; cuff concerns reported to nursing/medical staff—do not casually retape or deflate
- Breathing support: ventilator or non-invasive interface; oxygen device; SpO2 and respiratory pattern on the monitor
- Circulation: arterial line, central venous catheter, vasopressor/inotrope infusions—know that disconnection or displacement is an emergency
- Drains and tubes: intercostal catheters, surgical drains, nasogastric tubes, urinary catheters, temporary pacing wires if present
- Neurology/sedation: RASS or local sedation score, ability to follow commands, delirium risk
- Orders and holds: mobility restrictions, spinal precautions, recent procedures, anticoagulation extremes, open abdomen, unstable fractures
If anything looks disconnected, alarming, or unfamiliar, stop and ask the bedside nurse before moving the patient. Entry-level competence is humble and verbal, not silent and heroic.
Common lines and drains — what physios must respect
| Device | Physio-relevant caution |
|---|---|
| Peripheral IV | Avoid traction; secure during transfers |
| Central line (IJ/SC/femoral) | Do not pull; femoral lines may limit hip flexion/mobility options per unit policy |
| Arterial line | Transducer level matters for readings; protect site; bleeding risk if dislodged |
| ETT / tracheostomy | Two-person care for turning/mobilising when indicated; watch depth markings |
| Intercostal catheter (ICC) | Keep drainage system upright/below chest; do not clamp casually; watch for dislodgement |
| Surgical drains | Pin before roll if protocol requires; note output changes after session |
| IDC / NGT | Prevent traction injuries during sit-to-stand |
Ventilatory Support Concepts (Entry Level)
Why ventilate? To support oxygenation and/or ventilation (CO2 removal) and reduce work of breathing when the patient cannot meet demand safely.
Invasive mechanical ventilation via ETT or tracheostomy delivers controlled or supported breaths. Modes and settings (volume vs pressure, PEEP, FiO2, rate) are set by the ICU team. Your job is to understand that:
- Changing posture and activity can alter oxygen demand and ventilator synchrony
- Sedation, delirium, and weakness change cooperation
- Accidental extubation during mobilisation is a critical incident—use unit checklists and enough trained staff
Non-invasive ventilation (NIV) (e.g., BiPAP/CPAP interfaces) supports selected patients with hypercapnic or hypoxaemic failure. Physio sessions may need timing around NIV breaks or careful interface management with nursing collaboration.
High-flow nasal oxygen (HFNO) delivers heated humidified high-flow oxygen and some positive airway pressure effect. Patients may look “comfortable” yet remain critically ill—do not over-challenge without monitoring.
Oxygen delivery awareness
From lower to higher support (simplified continuum for cases):
- Nasal cannula / simple face mask
- Venturi (fixed performance) masks when precise FiO2 is needed
- Non-rebreather reservoir masks for high FiO2 short-term
- HFNO
- NIV
- Invasive ventilation
Titrate only within prescribed SpO2 targets. Many acutely ill patients have targets such as 92–96% or disease-specific ranges (e.g., some chronic CO2 retainers). If SpO2 falls or work of breathing rises during therapy, reduce demand, restore position/oxygen as per plan, and escalate if not recovering.
Positioning in Critical Care
- Upright and semi-recumbent postures often improve comfort and may assist ventilation compared with flat supine when allowed
- Side-lying for pressure care and regional ventilation—coordinate with lines and injuries
- Prone positioning for severe ARDS is a medical/nursing-led protocol with strict safety checks; physiotherapists may assist within team roles but do not improvise prone turns alone
- Watch for pressure injuries, brachial plexus stretch, and facial oedema themes in prolonged positioning
Early Mobilisation in ICU: Benefits and Hard Stops
Early progressive mobility (passive range → sitting on edge → standing → marching → walking with ventilator) reduces ICU-acquired weakness risk when done safely. It is criteria-based, not calendar-based bravado.
When NOT to mobilise (typical absolute/relative themes—follow local protocol)
Treat these as exam red lights unless a senior team explicitly clears a modified plan:
- Unstable hypotension on escalating vasopressors, or active titration crisis
- Uncontrolled tachy- or brady-arrhythmia with compromise
- Acute myocardial ischaemia or uncontrolled major bleeding
- Insecure airway or imminent intubation/extubation window per team plan
- Unstable spinal injury without clearance; unstable major fractures as ordered
- Raised intracranial pressure crises or acute neurological deterioration
- Severe agitation/delirium making safe handling impossible until settled
- Explicit medical “bed rest / no mobilisation” order
Relative cautions needing team discussion: femoral lines, open abdomen, high ventilator support with precarious oxygenation, new tracheostomy within unit-defined early window, severe thrombocytopenia/coagulopathy for some interventions.
If criteria fail: provide in-bed respiratory care as appropriate, passive/active-assisted limb care if allowed, pressure care contribution, and clear documentation of why mobility was deferred.
Multidisciplinary Teamwork
ICU physiotherapy is never solo heroism:
- Bedside nurse: current status, sedation, last suction, lines, plan of day
- Medical ICU team: mobility clearance, goals of care, weaning plan
- Speech pathology: swallow, communication, tracheostomy speaking valves when relevant
- Occupational therapy: cognitive/functional rehab synergy
- Family: orientation, realistic expectations, cultural needs
Shared goals might be “sit on edge for 3 minutes with SpO2 ≥ target” rather than “walk 50 metres at any cost.”
Australian Clinical Scenarios
Scenario A — Severe ARDS, day 2, deeply sedated, high ventilator support: focus on positioning with team, joint protection, secretion care only if indicated, no independent ambulation attempt.
Scenario B — Tracheostomised patient, awake, low ventilator support, stable BP off high-dose pressors, team clearance: planned sitting on edge with enough staff, airway secured, monitor SpO2/HR/BP/symptoms, stop if desaturation or distress fails to recover quickly.
Scenario C — Arterial line pulled during roll: compress/control as first aid within training, call for help immediately, do not continue the exercise plan.
APC Traps
- Mobilising despite escalating vasopressors and falling BP because “early mobility is always good”
- Disconnecting or ignoring ventilator alarms to “get the walk done”
- Treating ARDS solely with vigorous percussion
- Adjusting FiO2 or ventilator mode without authority
- Working silently without nurse communication in a complex bedspace
- Confusing “stable enough for passive ROM” with “stable enough for standing”
APC Case Patterns and Competency Links
Common item stems:
- Intubated patient, first visit → scan environment + nurse huddle before any transfer
- Escalating noradrenaline / falling MAP → defer out-of-bed mobility
- Early ARDS, dry lungs, high FiO2/PEEP → positioning support + joint care, not hourly vigorous percussion
- SpO2 fails to recover on edge of bed → stop, restore support/position, escalate
- New tracheostomy within unit-defined early window → follow local clearance, do not invent solo first walks
Map to Thresholds: professional judgment (know when not to treat), collaborative practice (ICU MDT), risk management (devices, airway, haemodynamics), and ethical practice (goals of care awareness without over-promising recovery timelines). Rural retrieval or step-down ward stems still use the same stability rules—lower staffing is never a reason to skip the environment scan.
ICU-acquired weakness (ICUAW) lens: prolonged critical illness produces profound weakness. Entry-level contribution is safe progressive loading when criteria allow, not heroic one-off 100 m walks on the day of instability. Passive/active-assisted range, sitting balance, and short standing trials are legitimate progressions. Document why mobility was deferred as carefully as you document successful sits—both are competent practice.
Closing Exam Anchor
Scan the ICU bedspace, respect devices and medical plans, support ARDS care with positioning and cautious progressive activity, and know clearly when not to mobilise. Entry-level excellence is safety plus teamwork.
Before mobilising an intubated ICU patient, which first step best reflects entry-level critical-care safety?
Increase tidal volume on the ventilator yourself to “prepare” the lungs
Complete an environment and stability scan (airway security, lines/drains, infusions, monitors, orders) and coordinate with the bedside nurse/team
Remove the arterial line temporarily so it cannot snag during standing
Disconnect monitoring leads for the whole session to reduce cable clutter
Which situation is the strongest reason to defer active out-of-bed mobilisation?
Stable patient on low ventilator support with team clearance and secure airway
Quiet alert patient after successful spontaneous breathing trial awaiting ordered extubation later today with explicit mobility OK
Compensated patient with a secure tracheostomy and documented stability criteria met
Hypotension on rapidly escalating vasopressors with ongoing haemodynamic instability
A patient with early ARDS is severely hypoxaemic on lung-protective ventilation, lightly sedated, and has minimal sputum. Which physiotherapy emphasis is most appropriate?
Support medical positioning protocols, protect joints, prevent secondary complications, and avoid non-indicated vigorous clearance as the main plan
Perform prolonged head-down percussion every hour to “open ARDS lungs”
Independently raise PEEP and FiO2 before each session without discussion
Force a 50-metre walk on day one regardless of oxygen and vasopressor status
During a sitting-on-edge session, an ICU patient’s SpO2 falls below the prescribed target and does not recover within a short rest with return to baseline support. What is the best next action?
Encourage faster marching to raise minute ventilation at all costs
Ignore SpO2 because the patient is talking
Stop the challenge, restore a safer position/support as planned, reassess, and escalate to the nurse/medical team if not recovering
Silence the monitor alarm and continue to the chair for documentation goals
Which oxygen/ventilatory action is within entry-level physiotherapy scope during a ward or ICU session?
Independently change the prescribed FiO2 target range and rewrite the medical oxygen order
Silence all ventilator alarms for the duration of standing practice
Work within the prescribed SpO2 target, reduce demand if desaturation occurs, restore planned support, and escalate if the patient does not recover
Extubate the patient at the bedside to make walking easier
Sections you finish are checked off in the contents.