13.2 ARDS, ICU and Critical Care Safety

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:

1. Airway: endotracheal tube (ETT) or tracheostomy position and security; cuff concerns reported to nursing/medical staff—do not casually retape or deflate
2. Breathing support: ventilator or non-invasive interface; oxygen device; SpO2 and respiratory pattern on the monitor
3. Circulation: arterial line, central venous catheter, vasopressor/inotrope infusions—know that disconnection or displacement is an emergency
4. Drains and tubes: intercostal catheters, surgical drains, nasogastric tubes, urinary catheters, temporary pacing wires if present
5. Neurology/sedation: RASS or local sedation score, ability to follow commands, delirium risk
6. 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

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.