Acute Respiratory Distress Syndrome (ARDS)

Clinically reviewed Aug 13, 2026 Updated Aug 30, 2026

Clinical Snapshot

Acute respiratory distress syndrome (ARDS) is an acute, diffuse inflammatory lung injury that increases pulmonary vascular permeability, causes widespread loss of aerated lung tissue, and produces hypoxemia refractory to simple oxygen therapy. It is not a single disease but a common final pathway triggered by a wide range of pulmonary and extrapulmonary insults — most often sepsis, pneumonia, aspiration, major trauma, or pancreatitis.[1] ARDS is diagnosed and graded using the Berlin Definition: acute onset within 1 week of a known insult, bilateral opacities not fully explained by effusion, collapse, or nodules, respiratory failure not fully explained by cardiac failure or fluid overload, and a PaO2/FiO2 ratio that stratifies severity into mild, moderate, and severe.[1]

The single most important concept for a pharmacist to hold onto is that ARDS management is primarily supportive, not primarily a drug-therapy disease — lung-protective mechanical ventilation is the cornerstone of care, and no drug has ever been shown to independently reduce ARDS mortality the way it has in sepsis or an acute coronary syndrome.[2] That does not mean pharmacotherapy is unimportant: real, specific, high-stakes pharmacist contributions exist throughout this chapter — correct neuromuscular blockade dosing and monitoring, weighing the genuinely evolving corticosteroid evidence, executing a conservative fluid strategy safely with diuretics, and getting sedation/analgesia strategy right for a ventilated patient — but every one of these sits around the ventilator strategy, not in place of it.

Recognize the Condition

Presentation

ARDS presents as acute, progressive dyspnea and tachypnea with hypoxemia that does not correct with modest increases in supplemental oxygen, typically emerging over hours to days (and by definition within 1 week) after a known clinical insult or a new/worsening respiratory symptom.[1] Auscultation often reveals diffuse crackles rather than focal findings, and the patient frequently appears more distressed than a simple pneumonia or exacerbation would explain. Because ARDS is a syndrome triggered by an underlying insult, the presenting picture is often dominated by that trigger (fever and productive cough in pneumonia-triggered ARDS, hypotension and altered mentation in sepsis-triggered ARDS, epigastric pain in pancreatitis-triggered ARDS) with progressive hypoxemic respiratory failure developing on top of it — recognizing that overlap is often what catches ARDS early rather than after intubation has already become unavoidable.

Common triggers

ARDS follows a pulmonary (direct) or extrapulmonary (indirect) insult to the lung.

Pulmonary (direct) insults

Pneumonia (bacterial, viral — including influenza and COVID-19, see the Community-Acquired Pneumonia and COVID-19 chapters — or fungal) is the most common direct cause. Also: aspiration of gastric contents, pulmonary contusion, inhalational or smoke injury, near-drowning, and fat embolism.

Extrapulmonary (indirect) insults

Sepsis is the single most common trigger of ARDS overall — see the Sepsis chapter for its own recognition and management pathway. Also: severe non-thoracic trauma with shock or massive transfusion, acute pancreatitis, transfusion-related acute lung injury (TRALI), drug overdose, and major burns.

Risk Factors

  • Sepsis — the single most common precipitant of ARDS.
  • Pneumonia, bacterial or viral (including influenza, COVID-19, and other respiratory viruses).
  • Aspiration of gastric contents.
  • Severe trauma, particularly with shock, pulmonary contusion, or multiple blood product transfusions.
  • Acute pancreatitis.
  • Massive or rapid blood product transfusion (transfusion-related acute lung injury, TRALI).
  • Inhalational injury, smoke exposure, or near-drowning.
  • Drug overdose.
  • Older age, chronic alcohol use, hypoalbuminemia, and higher baseline severity-of-illness scores are all associated with a higher risk of developing ARDS after a given insult, and with worse outcomes once it develops.
  • A prior episode of ARDS does not confer meaningful protection against a future episode.

Red Flags & Refer

Any of the following warrants immediate escalation to critical care — ARDS, once moderate or severe, is intrinsically an ICU-level illness and should never be managed on a general ward:

  • Hypoxemia refractory to escalating supplemental oxygen or requiring increasing FiO2/PEEP support — do not wait for a formal ARDS diagnosis to escalate the level of care.
  • Clinical or radiographic signs of impending respiratory failure (rising respiratory rate, accessory muscle use, altered mentation from hypoxemia or hypercapnia) — anticipate the need for intubation rather than reacting to arrest.
  • Refractory hypoxemia (PaO2/FiO2 at or below roughly 80-100 mmHg) despite optimized lung-protective ventilation and prone positioning — refer early to an ECMO-capable centre; this decision is time-sensitive and outcomes are worse when referral is delayed until multi-organ failure has already developed.
  • Sudden desaturation with asymmetric chest findings in a patient on positive-pressure ventilation — evaluate immediately for a tension pneumothorax/barotrauma, a genuine ventilator emergency requiring immediate needle decompression or chest tube, not simply a ventilator-setting adjustment.
  • Concurrent hemodynamic instability (septic or hypovolemic shock) — this changes fluid strategy sequencing (see Choose Initial Treatment) and needs concurrent shock management, not ARDS care in isolation.
  • ARDS in pregnancy — a high-risk, low-frequency presentation needing simultaneous maternal-fetal medicine and critical care involvement from the outset.

Assessment & Diagnosis

The Berlin Definition

ARDS is diagnosed using 4 criteria, all of which must be met.[1]

CriterionDefinition
TimingOnset within 1 week of a known clinical insult, or new or worsening respiratory symptoms.
Chest imagingBilateral opacities on chest radiograph or CT, not fully explained by effusion, lobar/lung collapse, or nodules.
Origin of edemaRespiratory failure not fully explained by cardiac failure or fluid overload. Obtain an objective assessment (e.g., echocardiography) to exclude hydrostatic pulmonary edema when no ARDS risk factor is present.
OxygenationSee the severity table below — graded by PaO2/FiO2 with a minimum PEEP or CPAP of 5 cm H2O.

Severity grading — PaO2/FiO2 ratio

Severity is assessed with the patient on PEEP or CPAP of at least 5 cm H2O — mild ARDS may be supported with non-invasive ventilation or CPAP if the setting allows it safely, but moderate and severe ARDS almost always require invasive mechanical ventilation.[1]

SeverityPaO2/FiO2
Mild200 mmHg < PaO2/FiO2 ≤ 300 mmHg
Moderate100 mmHg < PaO2/FiO2 ≤ 200 mmHg
SeverePaO2/FiO2 ≤ 100 mmHg

A live calculator is intentionally not provided for the PaO2/FiO2 ratio here — it is a single division that the bedside blood gas and ventilator display already provide, and the teaching table above is what actually needs to be understood (the exclusion-of-cardiac-cause and imaging criteria, not just the ratio) to apply the definition correctly.

Investigations

  • Arterial blood gas for PaO2/FiO2 — obtain and trend serially, not as a single snapshot, since severity can shift quickly in either direction.
  • Chest radiograph or CT to confirm bilateral opacities and help exclude an alternative explanation (large effusion, lobar collapse).
  • Echocardiography when the cause of pulmonary edema is not clearly explained by an identified ARDS risk factor, to help exclude a primarily cardiogenic process; natriuretic peptides (BNP/NT-proBNP) may support this assessment but are not diagnostic alone and can be elevated in critical illness for other reasons.
  • Source-directed workup based on the suspected trigger: blood/sputum/respiratory cultures and a full sepsis workup (see the Sepsis chapter) for a suspected infectious trigger, lipase/amylase and abdominal imaging for suspected pancreatitis, and a careful transfusion history and timeline when TRALI is possible.

Treatment Targets

  • Recognize ARDS early using the Berlin Definition and grade severity accurately, since severity drives the escalation ladder.
  • Deliver lung-protective ventilation to every patient with ARDS — low tidal volume, limited plateau pressure, and an appropriate PEEP strategy for severity.
  • Maintain adequate oxygenation (generally SpO2 88-95% or PaO2 55-80 mmHg) while explicitly accepting permissive hypoxemia and hypercapnia trade-offs rather than escalating ventilator settings to normalize numbers at the cost of lung injury.
  • Identify and treat the underlying trigger directly — source control and antimicrobial therapy for an infectious cause, management of pancreatitis, evaluation of a transfusion reaction.
  • Use prone positioning for moderate-severe disease, and escalate to ECMO referral early when hypoxemia remains refractory, rather than as a last resort.
  • Apply a conservative fluid strategy once shock has resolved and the patient is hemodynamically stable.
  • Use targeted, situational pharmacotherapy — neuromuscular blockade, corticosteroids — only where a specific indication applies, not routinely for every patient with ARDS.
  • Minimize iatrogenic harm: avoid unnecessarily deep or prolonged sedation, avoid unnecessarily prolonged paralysis, and prevent ventilator-associated pneumonia, ICU-acquired weakness, and delirium.
  • Support the earliest safe liberation from mechanical ventilation and address post-intensive-care recovery needs.

Choose Initial Treatment

Direct treatment rule

Supportive care is the primary therapy — pharmacotherapy is adjunctive and situational

For every patient with ARDS, regardless of severity:

  1. Lung-protective ventilation — target a tidal volume around 6 mL/kg predicted body weight (acceptable range 4-8 mL/kg PBW) and a plateau pressure below 30 cm H2O, minimizing driving pressure (plateau pressure minus PEEP) where possible.[2] Accept permissive hypercapnia (pH as low as roughly 7.15-7.30) rather than increasing tidal volume to normalize CO2.
  2. PEEP — use a higher-PEEP strategy over a lower-PEEP strategy for moderate-severe ARDS, selected from a standard PEEP/FiO2 table rather than an aggressive incremental recruitment-maneuver-based titration strategy, which trial evidence has linked to harm rather than benefit.[2]
  3. Treat the underlying trigger directly and concurrently — source-directed antimicrobial therapy for a pneumonia or sepsis trigger (see the Sepsis and Community-Acquired Pneumonia chapters), management of pancreatitis, or evaluation and cessation of an implicated transfusion. Ventilator management alone will not resolve ARDS if the trigger is left untreated.

Escalation ladder by severity and response

PaO2/FiO2 under 150 despite optimized lung-protective ventilation

Begin prone positioning — sessions of at least 16 consecutive hours, started early after a brief period of stabilization on low tidal volume ventilation.[3] This is a non-pharmacologic intervention (see Non-Pharmacologic Treatment) but is one of the very few measures in ARDS with a demonstrated mortality benefit, and should not be reserved as a late rescue option.

Persistent patient-ventilator dyssynchrony or refractory hypoxemia despite optimized sedation and prone positioning

Consider a time-limited (up to 48 hours) neuromuscular blockade infusion — cisatracurium is the agent with the strongest evidence base. This is a specific, situational indication, not a routine step for every severe ARDS patient: the more recent ROSE trial found no mortality benefit from routine early neuromuscular blockade paired with a high-PEEP strategy, and identified a signal for harm (ICU-acquired weakness, cardiovascular events) with routine use.[4] Reserve it for a genuine indication — dyssynchrony, refractory hypoxemia, or persistently elevated plateau/driving pressure — rather than defaulting to it in every severe case.

Moderate-severe ARDS, particularly early in its course

Consider corticosteroids — the 2024 SCCM focused update conditionally suggests corticosteroids for critically ill adults with ARDS (moderate-certainty evidence of a mortality benefit), but the panel was explicitly unable to recommend a specific molecule, dose, or duration given the available evidence.[5] This is a genuinely evolving area, not a settled one — see Pharmacologic Treatment Options and Drug Tables for the best-characterized published regimen, and Special Populations/Common Errors for the important caution against starting steroids very late in the illness course.

Refractory severe hypoxemia despite lung-protective ventilation, adequate PEEP, and prone positioning

Refer early to an ECMO-capable centre for consideration of veno-venous ECMO — this decision should be made proactively as hypoxemia proves refractory, not deferred until multi-organ failure has already developed.

Non-Pharmacologic Treatment

Lung-protective ventilation — the true cornerstone of ARDS care

  • Tidal volume around 6 mL/kg predicted body weight (PBW, calculated from height and sex — never actual body weight), acceptable range 4-8 mL/kg PBW.[2]
  • Plateau pressure below 30 cm H2O, minimizing driving pressure (plateau pressure minus PEEP) where achievable.[2]
  • Accept permissive hypercapnia and a lower target SpO2/PaO2 (generally SpO2 88-95% or PaO2 55-80 mmHg) rather than using injurious ventilator settings to normalize gas exchange; avoid hyperoxia as well as hypoxemia.
  • Use a higher-PEEP strategy from a standard PEEP/FiO2 table for moderate-severe ARDS; avoid an aggressive incremental recruitment-maneuver-based PEEP titration strategy, which has been associated with harm in trial evidence.[2]
  • Do not use high-frequency oscillatory ventilation (HFOV) routinely — trial evidence in moderate-severe ARDS has shown no benefit and a signal of harm; it is not a routine rescue strategy.[2]

Prone positioning

For moderate-severe ARDS with PaO2/FiO2 under roughly 150 despite optimized ventilator settings, prone positioning for sessions of at least 16 consecutive hours reduces mortality — this is one of the few ARDS interventions with genuine mortality-benefit evidence, and should be started early (after a brief period of stabilization) rather than reserved as a late rescue measure.[3] Prone positioning requires a trained team and careful protocol for safe turning, pressure-injury prevention, and line/tube security — see the Pressure Injuries chapter for skin-protection principles that apply directly here.

Conservative fluid management

Once shock has resolved and the patient is hemodynamically stable, target an even-to-negative fluid balance using a protocolized diuresis strategy (see Pharmacologic Treatment Options) rather than continued liberal fluid administration — this shortens the duration of mechanical ventilation and ICU stay without increasing non-pulmonary organ failure, though it has not been shown to independently reduce mortality.[6] Sequencing matters: this applies only after initial shock resuscitation is complete — a patient with concurrent septic or hypovolemic shock still needs the fluid resuscitation described in the Sepsis chapter first; the conservative strategy is a subsequent phase of care, not a substitute for adequate initial resuscitation.

Treat the underlying trigger

Ventilator management alone will not resolve ARDS if the precipitating insult is left untreated — source-directed antimicrobial therapy for a pneumonia or sepsis trigger (see the Sepsis and Community-Acquired Pneumonia chapters), management of pancreatitis, and evaluation of a suspected transfusion reaction are all core, concurrent parts of ARDS care, not an afterthought once the ventilator is set up.

Extracorporeal membrane oxygenation (ECMO)

Veno-venous ECMO is a rescue option for refractory severe hypoxemia despite optimized lung-protective ventilation and prone positioning, provided at expert centres with the necessary experience and infrastructure. Refer early once hypoxemia is proving refractory to standard measures rather than waiting until multi-organ failure has developed — outcomes are meaningfully worse with delayed referral.

Standard critical-care supportive bundle

  • Analgesia-first, lightest-effective sedation strategy with daily interruption/targeting once appropriate (see Pharmacologic Treatment Options).
  • Daily assessment for spontaneous awakening and spontaneous breathing trial candidacy, to support the earliest safe liberation from mechanical ventilation.
  • Pharmacologic VTE prophylaxis unless contraindicated.
  • Stress ulcer prophylaxis in patients at elevated GI bleeding risk.
  • Early enteral nutrition once hemodynamically stabilized.
  • A restrictive red blood cell transfusion strategy rather than a liberal one.
  • Early mobilization once feasible, to reduce ICU-acquired weakness — a particular concern in any patient who has received neuromuscular blockade or prolonged deep sedation.

Pharmacologic Treatment Options

Drug / interventionRoleDose / useImportant adverse effectsTeaching points
Cisatracurium
Special situation
Neuromuscular blockade, severe ARDS with a specific indication15 mg IV bolus, then 37.5 mg/hour continuous IV infusion for up to 48 hours; titrate to train-of-four 1-2/4 twitches where monitoring is availableICU-acquired weakness, prolonged paralysis, cardiovascular eventsNever without adequate concurrent sedation/analgesia. Reserve for persistent patient-ventilator dyssynchrony, refractory hypoxemia, or persistently high plateau/driving pressure despite optimized sedation — not routine, given the neutral/harm signal from the ROSE trial.
Dexamethasone
Special situation
Adjunctive corticosteroid, moderate-severe ARDS, started early20 mg IV once daily for 5 days, then 10 mg IV once daily for 5 days (10-day course)Hyperglycemia, secondary infection risk, neuromuscular weakness (particularly combined with neuromuscular blockade), GI bleeding riskThe best-characterized published regimen. Current guidance conditionally suggests corticosteroids for ARDS but does not endorse one specific molecule/dose/duration — avoid starting beyond roughly 2 weeks after ARDS onset, where evidence suggests possible harm rather than benefit.
Methylprednisolone
Alternative
Adjunctive corticosteroid, institution-dependent alternative regimenNo single dose is established by current guidance; follow local protocolSame corticosteroid class effects as dexamethasoneAn alternative when a local protocol favours it over dexamethasone; the 2024 SCCM focused update does not prefer one molecule over another.
Furosemide
Preferred
Diuresis to support a conservative fluid strategy once stableIndividualized IV bolus or infusion, titrated to an even-to-negative daily fluid balance per protocolHypokalemia, hypomagnesemia, hypovolemia if overzealous, ototoxicity at high dosesApply only after shock has resolved and the patient is hemodynamically stable — never during the active fluid-resuscitation phase of septic or hypovolemic shock.
Fentanyl
Preferred
Primary analgesic for the ventilated ARDS patientContinuous IV infusion, titrated to a validated pain scaleIleus, tolerance and withdrawal with prolonged useAnalgesia-first strategy — treat pain before adding or escalating a sedative; this reduces total sedative exposure over the admission.
Propofol
Preferred
Primary sedative for mechanically ventilated ARDS patientsContinuous IV infusion, titrated to the lightest sedation level that meets the clinical goal (deeper only when specifically needed for ventilator synchrony, prone positioning, or concurrent neuromuscular blockade)Propofol infusion syndrome with high-dose/prolonged use, hypotension, hypertriglyceridemiaPreferred, along with dexmedetomidine, over benzodiazepines as a first-line sedative — benzodiazepine use is associated with more delirium and a longer duration of mechanical ventilation.
Dexmedetomidine
Alternative
Alternative/adjunct sedative, particularly to facilitate lighter sedationContinuous IV infusion, titrated per protocolBradycardia, hypotensionUseful specifically when a lighter sedation target and lower delirium risk are priorities; not typically sufficient alone for a deeply sedated, dyssynchronous, or actively paralyzed patient.
Treating the underlying trigger — source-directed antimicrobial therapy for an infectious trigger is core ARDS care, but is deliberately not repeated here in full; see the Sepsis and Community-Acquired Pneumonia chapters for specific agents and doses. ARDS itself is never an indication for empiric broad-spectrum antibiotics absent a suspected or confirmed infectious trigger.

Special Populations

Pregnancy

ARDS in pregnancy is high-risk and needs simultaneous obstetric/maternal-fetal medicine and critical care involvement from the outset. Common triggers include viral pneumonia (influenza, COVID-19), aspiration, and pregnancy-specific causes that can mimic or coexist with ARDS — amniotic fluid embolism, tocolytic-associated pulmonary edema, and severe preeclampsia/HELLP-related pulmonary edema (see the Preeclampsia chapter to distinguish these from primary ARDS). Lung-protective ventilation targets are the same, but permissive hypercapnia is applied more cautiously — maternal CO2 crosses the placenta and affects fetal acid-base status, so involve obstetric anesthesia/maternal-fetal medicine in setting ventilator targets rather than applying the standard adult hypercapnia range unmodified. Positioning for a pregnant patient beyond the point of significant uterine size needs specific modification (left lateral uterine displacement, adapted bolstering) rather than the standard prone protocol used outside pregnancy — this is managed by the critical care/obstetric team together, not as a simple substitution. If corticosteroids are given for ARDS in a preterm gestation, this can incidentally overlap with fetal lung maturation benefit — a genuine but coincidental additional benefit, not itself a reason to give corticosteroids outside their ARDS indication.

Breastfeeding

This is rarely an immediate clinical question during acute critical illness, since a patient with moderate-severe ARDS is typically sedated and mechanically ventilated. Once the patient has recovered enough for the question to be relevant, dexamethasone and methylprednisolone at standard treatment doses are both considered compatible with breastfeeding; confirm specifics against each drug's own Drug Database entry.

Renal impairment

Cisatracurium undergoes organ-independent Hofmann elimination (spontaneous degradation at physiologic pH and temperature) rather than renal or hepatic clearance — a genuine practical advantage that makes it a reasonable neuromuscular blocking agent choice in renal impairment with minimal dose adjustment needed. Furosemide may need higher doses in renal impairment or diuretic resistance; when executing a conservative fluid strategy in a patient with concurrent or evolving acute kidney injury, balance fluid removal against renal perfusion carefully and involve nephrology rather than pursuing an increasingly negative balance in isolation.

Hepatic impairment

Cisatracurium's Hofmann elimination is also independent of hepatic function, making it a preferred neuromuscular blocking agent in hepatic impairment. Sedative and analgesic dosing (propofol, fentanyl) may need downward adjustment with significant hepatic impairment given their hepatic metabolism — review each agent's product monograph for specifics.

Obesity

Calculate tidal volume using predicted body weight (from height and sex) — never actual body weight; using actual body weight in an obese patient produces a clinically significant tidal volume overshoot and is one of the most common, most consequential dosing errors in ARDS care. Sedative, analgesic, and neuromuscular blocking agent dosing, by contrast, is generally based on actual or adjusted body weight per the individual agent's own dosing guidance — the distinction between PBW-based ventilator dosing and weight-based drug dosing is worth stating explicitly, since conflating the two in either direction is a real error.

Older adults

Increased susceptibility to sedative accumulation and delirium argues for an even more deliberately light sedation target and vigilant delirium screening. Older adults also carry a higher baseline risk of ICU-acquired weakness, which strengthens the case for reserving neuromuscular blockade strictly for a specific indication rather than routine use, and for early mobilization once feasible.

COVID-19 and other viral triggers

General ARDS lung-protective ventilation, PEEP, and prone-positioning principles apply the same way regardless of trigger. Virus-specific antiviral and immunomodulatory therapy (including the specific dexamethasone evidence base that emerged from COVID-19 respiratory failure trials) is addressed in the COVID-19 and Influenza chapters rather than duplicated here — treat this chapter's corticosteroid guidance as the general ARDS evidence base, and defer to the virus-specific chapter for a viral trigger.

Monitoring & Follow-Up

Trend PaO2/FiO2 serially (not as a single value) to track severity and guide escalation or de-escalation, and review plateau pressure and driving pressure at every ventilator check to confirm lung-protective targets are actually being met, not merely intended.[2] Screen for delirium and assess sedation depth against a validated scale daily, and assess spontaneous awakening/breathing trial candidacy daily once the patient is stabilizing, to support the earliest safe liberation from mechanical ventilation.

Neuromuscular blockade

Use train-of-four monitoring where the infusion continues beyond the initial period, and reassess the ongoing need for it daily — discontinue at 48 hours per the trial-based protocol unless a specific ongoing indication genuinely persists.[4] Because a paralyzed patient cannot report distress, concurrent sedation and analgesia adequacy must be actively confirmed through physiologic surrogates (heart rate, blood pressure, processed EEG monitoring where available) rather than assumed — under-sedation during paralysis is a serious safety failure, not a comfort issue.

Corticosteroids

Monitor blood glucose closely, watch for secondary infection, and reassess the ongoing need daily rather than allowing an open-ended course — follow the specific completed regimen (see Drug Tables) rather than continuing indefinitely by default.[5]

Conservative fluid strategy

Review daily fluid balance, renal function, and electrolytes alongside diuresis, and track perfusion markers (lactate, urine output, mentation) to confirm the conservative strategy is not producing under-resuscitation or organ hypoperfusion rather than its intended benefit.[6]

Transitions of care

Medication reconciliation at every transition — ICU to ward, and hospital to home — is essential: sedatives, neuromuscular blocking agents, and corticosteroids started acutely must be actively and deliberately stopped as the patient recovers, not silently carried forward through a handoff. Before discharge, screen for physical, cognitive, and psychological impairment consistent with post-intensive care syndrome, and arrange follow-up for anything identified — mechanically ventilated ARDS survivors are at meaningfully elevated risk for this.

Treatment Failure / Next Step

  1. Worsening hypoxemia despite lung-protective ventilation at the intended PEEP: confirm plateau and driving pressures are actually within target (not merely intended), escalate PEEP per the standard table, and begin prone positioning if not already started and PaO2/FiO2 is under roughly 150.[2]
  2. Persistent patient-ventilator dyssynchrony despite optimized analgesia and sedation: consider a time-limited neuromuscular blockade infusion rather than continuing to escalate sedation depth indefinitely.
  3. Refractory severe hypoxemia despite lung-protective ventilation, adequate PEEP, and prone positioning: refer early to an ECMO-capable centre — this should happen as hypoxemia proves refractory, not once multi-organ failure has already set in.
  4. No improvement, or worsening, despite standard supportive measures: reassess for an alternative or missed diagnosis (cardiogenic pulmonary edema, pulmonary embolism, diffuse alveolar hemorrhage, acute eosinophilic pneumonia) rather than assuming this is simply refractory ARDS.
  5. New fever or clinical deterioration during the ICU course: reassess for an uncontrolled or new infectious source — ventilator-associated pneumonia, a missed original source, or drug fever — rather than attributing it to the natural course of ARDS.
  6. Persistent oliguria or apparent fluid intolerance during a conservative fluid strategy: reassess volume status and renal function before continuing aggressive diuresis, and involve nephrology if acute kidney injury is progressing.

Common Errors to Avoid

  • Calculating tidal volume from actual body weight instead of predicted body weight — a common, clinically significant dosing error, especially in obese patients.
  • Treating ARDS as primarily a pharmacotherapy problem — reaching for a drug (a corticosteroid, neuromuscular blockade) before lung-protective ventilation and, where indicated, prone positioning are actually optimized.[2]
  • Continuing an aggressive fluid-resuscitation strategy well past the point of hemodynamic stability instead of transitioning to a conservative fluid strategy once shock has resolved.[6]
  • Starting corticosteroids very late in the illness course (beyond roughly 2 weeks from ARDS onset) — evidence from the persistent-ARDS steroid literature suggests possible harm rather than benefit at that point, not simply reduced benefit.
  • Initiating neuromuscular blockade without first ensuring adequate concurrent sedation and analgesia — a paralyzed, under-sedated patient is a serious safety failure.
  • Continuing neuromuscular blockade indefinitely rather than reassessing daily and stopping at 48 hours (or sooner) absent a specific ongoing indication.[4]
  • Applying an aggressive incremental PEEP-titration or recruitment-maneuver strategy instead of a standard PEEP/FiO2 table — trial evidence favours the table-based approach.[2]
  • Delaying prone positioning or ECMO referral until the patient is already in multi-organ failure, rather than initiating them at the point the evidence supports.[3]
  • Focusing solely on ventilator management while missing or delaying treatment of the underlying trigger (infection, pancreatitis, a transfusion reaction).
  • Letting acutely started sedatives, neuromuscular blocking agents, or corticosteroids continue by default through care transitions instead of actively stopping them as the patient improves.

Clinical Decision Algorithm

Algorithm A — Diagnosis and severity grading
Acute (within 1 week) new or worsening hypoxemic respiratory failure with a plausible ARDS-risk insult
Bilateral opacities on chest imaging, not fully explained by effusion, collapse, or nodules?[1]
Yes, and not fully explained by cardiac failure or fluid overload (confirm objectively, e.g. echocardiography, if no ARDS risk factor is present)
Berlin criteria met — grade severity by PaO2/FiO2 on PEEP/CPAP ≥5 cm H2O
An alternative explanation is more likely (cardiogenic edema, atelectasis, effusion)
Reconsider the diagnosis — investigate and treat the actual cause instead
Mild: 200 < PaO2/FiO2 ≤ 300
May be supported with non-invasive ventilation/CPAP if the setting allows it safely; reassess frequently for progression
Moderate: 100 < PaO2/FiO2 ≤ 200
Invasive mechanical ventilation with lung-protective settings; proceed to Algorithm B
Severe: PaO2/FiO2 ≤ 100
Invasive mechanical ventilation with lung-protective settings; proceed to Algorithm B with a lower threshold for prone positioning and escalation
Algorithm B — Ventilation and escalation ladder
ARDS confirmed — begin lung-protective ventilation for every patient (~6 mL/kg PBW, range 4-8; plateau <30 cm H2O; PEEP per standard table for severity)[2]
Reassess oxygenation and plateau/driving pressure
PaO2/FiO2 under 150 despite optimized ventilator settings
Begin prone positioning — sessions of at least 16 consecutive hours[3]
PaO2/FiO2 ≥150, or already proned with response
Continue lung-protective ventilation; reassess regularly for de-escalation as the patient improves
Persistent patient-ventilator dyssynchrony or refractory hypoxemia despite optimized sedation and prone positioning
Consider a time-limited (≤48h) cisatracurium infusion — a specific indication, not a routine step[4]
Adequately synchronous, oxygenation improving
Continue current strategy; reassess sedation depth daily; target the earliest safe liberation from ventilation
Refractory severe hypoxemia despite lung-protective ventilation, adequate PEEP, and prone positioning — refer early to an ECMO-capable centre
Algorithm C — Adjunct pharmacotherapy and treating the underlying cause
Confirm the underlying ARDS trigger and treat it directly and concurrently with ventilator management
Infectious trigger (pneumonia, sepsis)
Source-directed antimicrobial therapy per the Sepsis / Community-Acquired Pneumonia chapter
Non-infectious trigger (pancreatitis, transfusion reaction, aspiration, trauma)
Manage the specific identified cause directly
Trigger unclear
Continue targeted workup while treating supportively
Once hemodynamically stable (shock resolved), transition to a conservative fluid strategy with protocolized diuresis[6]
For moderate-severe ARDS, consider corticosteroids (e.g., dexamethasone 20 mg IV daily x5 days then 10 mg IV daily x5 days), started early — individualize per current evolving guidance rather than treating this as mandatory for every patient[5]
Reassess daily — discontinue neuromuscular blockade, corticosteroids, and unnecessarily deep sedation as soon as they are no longer specifically indicated

Drug Tables

How to use this table: Doses are adult ICU doses and require patient-specific confirmation, including renal/hepatic adjustment where relevant. Select any drug name to open its complete Pharmasist Drug Database page. Antimicrobial therapy for an infectious ARDS trigger is intentionally not repeated here — see the Sepsis and Community-Acquired Pneumonia drug tables for that content.

Neuromuscular Blocking Agent

Reserve for a specific indication (persistent patient-ventilator dyssynchrony, refractory hypoxemia, or persistently elevated plateau/driving pressure despite optimized sedation) — not routine for every severe ARDS patient. Never administer without confirmed, adequate concurrent sedation and analgesia.

DrugDosageAdverse effectsDrug interactionsComments
Cisatracurium
Loading dose: 15 mg IV bolus
Maintenance: 37.5 mg/hour continuous IV infusion for up to 48 hours, reassessed daily and titrated to train-of-four where monitoring is available
ICU-acquired weakness (risk increases with duration and concurrent corticosteroid use), prolonged paralysis, tachycardia/bradycardia, histamine-related flushing or bronchospasm (uncommon)Potentiated by aminoglycosides, some volatile anesthetics, and hypothermia/hypokalemia/hypermagnesemia; antagonized by phenytoin and carbamazepine with chronic useUndergoes organ-independent Hofmann elimination — minimal dose adjustment needed in renal or hepatic impairment, a genuine practical advantage over other neuromuscular blockers in this setting. Titrate to train-of-four 1-2/4 twitches where monitoring is available rather than using the fixed infusion rate unmonitored throughout.

Corticosteroids

A genuinely evolving evidence area. The 2024 SCCM focused update conditionally suggests corticosteroids for critically ill adults with ARDS (moderate-certainty mortality benefit) but does not endorse a specific molecule, dose, or duration. Avoid initiating beyond roughly 2 weeks after ARDS onset — the persistent-ARDS steroid literature suggests possible harm, not simply reduced benefit, with late initiation.

DrugDosageAdverse effectsDrug interactionsComments
Dexamethasone
Adults: 20 mg IV once daily for 5 days, then 10 mg IV once daily for 5 days (10-day total course)
Hyperglycemia, secondary/opportunistic infection risk, neuromuscular weakness (particularly when combined with a neuromuscular blocking agent), GI bleeding risk, psychiatric effects with higher dosesMay reduce antibody response if a live-virus vaccine is given concurrently; enhances hyperglycemic effect of other agentsThe best-characterized published regimen for moderate-severe ARDS, ideally started early in the illness course.
Methylprednisolone
Adults: Per local ICU protocol — no consensus regimen; do not exceed roughly 2 weeks from ARDS onset without reassessing benefit
Same corticosteroid class effects as dexamethasoneSame corticosteroid class interactions as dexamethasoneAn institution-dependent alternative when local protocol favours it; no single dose is established as preferred by current guidance.

Analgesia and Sedation

Use an analgesia-first strategy — treat pain before adding or escalating a sedative — and target the lightest sedation level that meets the clinical goal, deepening only when specifically required for ventilator synchrony, prone positioning, or concurrent neuromuscular blockade.

DrugDosageAdverse effectsDrug interactionsComments
Fentanyl
Adults: Continuous IV infusion, titrated per protocol
Ileus, tolerance and withdrawal with prolonged infusion, respiratory depression (less clinically relevant while ventilated)Enhanced sedation with other CNS depressants; caution with concurrent serotonergic agentsPrimary analgesic of choice for the ventilated ARDS patient; titrate to a validated pain scale before layering on additional sedation.
Propofol
Adults: Continuous IV infusion, titrated to the lightest effective sedation target
Propofol infusion syndrome with high-dose or prolonged use, hypotension, hypertriglyceridemia, injection-site painEnhanced hypotension with other vasodilators/negative inotropesPreferred first-line sedative, along with dexmedetomidine, over benzodiazepines — benzodiazepine use is associated with more delirium and longer duration of mechanical ventilation. Monitor triglycerides with prolonged high-dose use.
Dexmedetomidine
Adults: Continuous IV infusion, titrated per protocol
Bradycardia, hypotensionEnhanced bradycardia/hypotension with other sympatholytics or negative chronotropesUseful particularly to facilitate a lighter sedation target and reduce delirium risk; generally not sufficient alone for a deeply sedated, dyssynchronous, or actively paralyzed patient.

Diuretic (Conservative Fluid Management)

Apply only once shock has resolved and the patient is hemodynamically stable — never during the active fluid-resuscitation phase of septic or hypovolemic shock.

DrugDosageAdverse effectsDrug interactionsComments
Furosemide
Adults: Individualized IV bolus or continuous infusion, titrated per protocol
Hypokalemia, hypomagnesemia, hypovolemia and hypotension if overzealous, ototoxicity at high doses/rapid infusionEnhanced ototoxicity with concurrent aminoglycosides; enhanced hypokalemia with other potassium-wasting drugsTitrate to an even-to-negative daily fluid balance per protocol, monitoring renal function and electrolytes closely; higher doses may be needed with renal impairment or diuretic resistance.

References

  1. Acute Respiratory Distress Syndrome: The Berlin Definition — ARDS Definition Task Force (Ranieri VM, Rubenfeld GD, Thompson BT, et al.), JAMA. JAMA 2012;307(23):2526-2533
  2. An Official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine Clinical Practice Guideline: Mechanical Ventilation in Adult Patients with Acute Respiratory Distress Syndrome — American Journal of Respiratory and Critical Care Medicine (Fan E, Del Sorbo L, Goligher EC, et al.). Am J Respir Crit Care Med 2017;195(9):1253-1263
  3. Prone Positioning in Severe Acute Respiratory Distress Syndrome — New England Journal of Medicine (Guérin C, Reignier J, Richard J-C, et al.). N Engl J Med 2013;368(23):2159-2168
  4. Early Neuromuscular Blockade in the Acute Respiratory Distress Syndrome — New England Journal of Medicine, National Heart, Lung, and Blood Institute PETAL Clinical Trials Network (Moss M, Huang DT, Brower RG, et al.). N Engl J Med 2019;380(21):1997-2008
  5. 2024 Focused Update: Guidelines on Use of Corticosteroids in Sepsis, Acute Respiratory Distress Syndrome, and Community-Acquired Pneumonia — Critical Care Medicine, Society of Critical Care Medicine (Chaudhuri D, Nei AM, Rochwerg B, et al.). Crit Care Med 2024;52(5):e219-e233
  6. Comparison of Two Fluid-Management Strategies in Acute Lung Injury — New England Journal of Medicine, National Heart, Lung, and Blood Institute ARDS Clinical Trials Network (Wiedemann HP, Wheeler AP, Bernard GR, et al.). N Engl J Med 2006;354(24):2564-2575

Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.

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