Spontaneous vs Controlled Mechanical Ventilation in Acute Hypoxemic Respiratory Failure (SVALBARD)

Spontaneous Versus Controlled Mechanical Ventilation in Patients With Acute Hypoxemic Respiratory Failure: A Feasibility Study and Pilot Trial

Acute hypoxemic respiratory failure may progress to acute respiratory distress syndrome, a life-threatening condition that often requires mechanical ventilation. The optimal ventilation strategy in this patient population remains uncertain.

The SVALBARD trial is a feasibility and pilot study designed to compare spontaneous versus controlled mechanical ventilation in patients with acute hypoxemia respiratory failure.

The primary objective is to assess the feasibility of the study procedures and interventions, while also collecting descriptive data on key clinical variables to inform the design of a future randomized controlled trial.

Study Overview

• Status: Not yet recruiting
• Conditions: Acute Respiratory Distress Syndrome (ARDS); Acute Hypoxemic Respiratory Failure
• Intervention / Treatment: Procedure: Spontaneous Ventilation Strategy; Procedure: Controlled Ventilation Strategy

Detailed Description

Acute hypoxemic respiratory failure is a condition that can progress to acute respiratory distress syndrome (ARDS), requiring invasive mechanical ventilation to support gas exchange and limit lung injury. ARDS guidelines recommend lung-protective ventilation strategies-specifically low tidal volumes and limited airway pressures-to reduce ventilator-induced lung injury. Observational studies, including the global LUNG SAFE project, have described the epidemiology and management of acute hypoxemic respiratory failure and ARDS. These studies report high mortality rates (global hospital mortality, 38.6%) associated with the severity of lung injury rather than strict fulfilment of ARDS criteria. They also reveal variability in the application of evidence-based ventilation strategies across institutions. This inconsistency highlights a barrier to progress: the lack of conclusive evidence guiding ventilation management in patients with acute hypoxemic respiratory failure.

One unresolved issue is the role of spontaneous breathing during mechanical ventilation. Observational studies suggest that allowing spontaneous effort may reduce need for sedation and increase ventilator-free days. In contrast, preclinical models indicate that spontaneous breathing in severe lung injury may worsen outcomes through mechanisms such as patient-ventilator asynchrony and regional overdistension. This contrast underscores the need to balance potential benefits against physiological risks in the absence of adequate trial data. ARDS guidelines do not provide clear recommendations on this issue due to limited evidence. Only one large RCT has compared controlled ventilation to spontaneous breathing modes, finding no difference in short-term outcomes and not assessing long-term endpoints such as cognitive impairment or quality of life.As a result, clinicians must choose between guideline-based controlled ventilation and approaches that incorporate spontaneous breathing, within the context of evolving sedation practices and recovery goals. Given the variability of acute hypoxemic respiratory failure and the current evidence gap, genuine uncertainty ('clinical equipoise') exists regarding the optimal ventilation strategy. This supports the need for well-designed RCTs to determine whether spontaneous ventilation offers clinical benefit or harm. A recent survey of Nordic clinicians showed support for such a trial in patients with moderately severe acute hypoxemic respiratory failure, underscoring the relevance of this research.

The SVALBARD study is a feasibility and pilot trial comparing spontaneous and controlled mechanical ventilation in patients with acute hypoxemic respiratory failure. The study will evaluate whether it is possible to recruit patients, apply the assigned ventilation strategies, and collect the required data in a reliable way.

In addition, the study will collect descriptive clinical data to better understand patient characteristics and outcomes. The results will be used to improve the design and planning of a future randomized controlled trial.

The trial will accrue 80 patients from eight different intensive care units, four in Norway and four in Denmark.

• Study Type: Interventional
• Enrollment (Estimated): 80
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jon Henrik Laake, MD, PHD; Phone Number: 0047 97660919; Email: jlaake@ous-hf.no
• Study Contact Backup: Name: Tayyba Naz Aslam, MD; Email: tayasl@ous-hf.no

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

We will include patients who fulfil all the following criteria:

• Acutely admitted to the ICU
• AND age ≥ 18 years
• AND invasive mechanical ventilation via endotracheal tube or tracheostomy for less than 24 hours
• AND moderate acute hypoxemic respiratory failure, defined as a PaO₂-FiO₂ ratio between 13.3-26.6 kPa (100-200 mmHg) with PEEP ≥ 5 cm H2O, based on arterial blood gas analysis obtained within 2 hours before randomisation.
• AND new pulmonary infiltrate (uni- or bilateral) on chest x-ray or CT-scan obtained no more than 24 hours before randomisation.

Exclusion Criteria:

• Previously randomised into the SVALBARD trial.
• Informed consent following inclusion expected to be unobtainable
• Patient under coercive measures
• Withdrawal from active therapy or brain death deemed imminent.
• Chronic hypercapnic respiratory failure defined as PaCO2 > 8 kPa (60 mm Hg) in the outpatient setting.
• Listed for lung transplant.
• Acute heart failure / acute myocardial infarction / cardiac arrest during or causing index ICU admission.
• Use of home oxygen.
• Chronic mechanical ventilation for any reason except for non-invasive mechanical ventilation (CPAP/BIPAP) used solely for sleep apnoea disorder.
• Currently receiving ECMO therapy.
• Burns >70 % total body surface.
• Acute brain injury or stroke (any, including subarachnoid haemorrhage, SAH).
• Intracranial hypertension.
• Patients with planned repeat surgical interventions during current stay in ICU.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Spontaneous ventilation; Invasive mechanical ventilation in which the patient initiates some or all breaths, and the ventilator assists or supports those spontaneous efforts.	Procedure: Spontaneous Ventilation Strategy; Invasive mechanical ventilation strategy allowing spontaneous breathing while receiving ventilatory support from a standard ICU mechanical ventilator.
Active Comparator: Controlled ventilation; Invasive mechanical ventilation in which all breaths are delivered by the ventilator, with no patient-initiated respiratory effort.	Procedure: Controlled Ventilation Strategy; Invasive mechanical ventilation strategy in which spontaneous respiratory effort is suppressed and breaths are fully delivered by a standard ICU mechanical ventilator.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recruitment Rate	Proportion of eligible patients who are enrolled in the trial (primary feasibility outcome).	1 year from trial initiation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Consent Rate	Proportion of eligible patients who provide informed consent to participate in the trial.	1 year from trial initiation
Randomisation Rate	Proportion of consented participants who are randomised.	1 year from trial initiation
Protocol Adherence	Proportion of study procedures completed according to protocol requirements.	1 year from trial initiation
Major Protocol Violations	Proportion of enrolled participants with at least one major protocol deviation.	1 year from trial initiation
Retention Rate	Proportion of randomised participants who complete study follow-up.	1 year from trial initiation
Time to Completion of Feasibility Study	Time from trial initiation to completion of feasibility study recruitment and follow-up.	Up to 1 year
Proportion of Participants Achieving Therapeutic Target at 48 Hours	Proportion of randomised participants achieving the predefined therapeutic target within 48 hours after randomisation.	48 hours from randomisation
Between-Group Difference in Therapeutic Target Attainment at 48 Hours	Difference between study groups in the proportion of participants achieving the predefined therapeutic target at 48 hours.	48 hours
Proportion of Missing Therapeutic Target Data at 48 Hours	Proportion of randomised participants with missing data for the predefined therapeutic target assessed 48 hours after randomisation.	48 hours from randomisation
Clinical: All-Cause Mortality at 30 Days	Proportion of enrolled participants who have died from any cause by 30 days.	30 days
Clinical: All-Cause Mortality at 90 Days	Proportion of enrolled participants who have died from any cause by 90 days.	90 days
Clinical: All-Cause Mortality at 180 Days	Proportion of enrolled participants who have died from any cause by 180 days.	180 days
Clinical: Clinical: Days Alive and Free of Life Support at 90 Days	Number of days alive and free of life support (invasive mechanical ventilation, renal replacement therapy, or vasoactive drug support) from randomisation through day 90. Life support-free days are calculated as the number of calendar days alive and free of all listed life support modalities during the 90-day period. Participants who die before day 90 will be assigned 0 days.	90 days
Clinical: Days Alive and Out of Hospital at 90 Days	Number of days alive and out of hospital from randomisation through day 90. Participants who die before day 90 will be assigned 0 days.	90 days
Clinical: Health-related quality of life (EQ-5D-5L Index Score)	Health-related quality of life measured using the EuroQol 5-Dimension 5-Level (EQ-5D-5L) index score. The index value ranges from less than 0 (health state worse than death) to 1 (best health), with higher scores indicating better health. Participants who die before assessment will be assigned a value of 0.	180 days
Clinical: Health-Related Quality of Life (EQ-5D Visual Analogue Scale Score)	Health-related quality of life measured using the EQ-5D Visual Analogue Scale (VAS), ranging from 0 (worst imaginable health) to 100 (best imaginable health). Higher scores indicate better health. Participants who die before assessment will be assigned a value of 0.	180 days
Clinical: Montreal Cognitive Assessment (MoCA) Score at 180 Days	Cognitive function assessed using the Montreal Cognitive Assessment (MoCA) Version 2.1 (telephone version). Scores range from 0 to 15, with higher scores indicating better cognitive function. Participants who die before assessment will be assigned a score of 0.	180 days
Clinical: Impact of Event Scale-6 (IES-6) Score at 180 Days	Post-traumatic stress symptoms assessed using the Impact of Event Scale-6 (IES-6). The scale consists of six items rated from 0 (not at all) to 4 (extremely). The mean score ranges from 0 to 4, with higher scores indicating more severe post-traumatic stress symptoms.	180 days
Clinical: Modified Medical Research Council (mMRC) Dyspnea Scale Score at 180 Days	Dyspnea assessed using the Modified Medical Research Council (mMRC) Dyspnea Scale. Scores range from 0 (breathless only with strenuous exercise) to 4 (too breathless to leave the house or while dressing/undressing), with higher scores indicating worse dyspnea.	180 days
Clinical: Chalder Fatigue Questionnaire (CFQ) Score at 180 Days	Fatigue assessed using the Chalder Fatigue Questionnaire (CFQ), consisting of 11 items scored from 0 to 3. Total scores range from 0 to 33, with higher scores indicating greater fatigue.	180 days

Collaborators and Investigators

• Sponsor: Oslo University Hospital
• Collaborators: Rigshospitalet, Denmark; Aalborg University Hospital

Publications and helpful links

General Publications

• Aslam TN, Klitgaard TL, Ahlstedt CAO, Andersen FH, Chew MS, Collet MO, Cronhjort M, Estrup S, Fossum OK, Frisvold SK, Gillmann HJ, Granholm A, Gundem TM, Hauss K, Hollenberg J, Huanca Condori ME, Hastbacka J, Johnstad BA, Keus E, Kjaer MN, Klepstad P, Krag M, Kvale R, Malbrain MLNG, Meyhoff CS, Morgan M, Moller A, Pfortmueller CA, Poulsen LM, Robertson AC, Schefold JC, Schjorring OL, Siegemund M, Sigurdsson MI, Sjovall F, Strand K, Stueber T, Szczeklik W, Wahlin RR, Wangberg HL, Wian KA, Wichmann S, Hofso K, Moller MH, Perner A, Rasmussen BS, Laake JH; SVALBARD investigators. A survey of preferences for respiratory support in the intensive care unit for patients with acute hypoxaemic respiratory failure. Acta Anaesthesiol Scand. 2023 Nov;67(10):1383-1394. doi: 10.1111/aas.14317. Epub 2023 Sep 22.
• Aslam TN, Klitgaard TL, Moller MH, Perner A, Hofso K, Skrubbeltrang C, Rasmussen BS, Laake JH. Spontaneous Versus Controlled Mechanical Ventilation in Patients With Acute Respiratory Distress Syndrome-A Scoping Review. Acta Anaesthesiol Scand. 2025 Sep;69(8):e70096. doi: 10.1111/aas.70096.
• Aslam TN, Klitgaard TL, Moller MH, Perner A, Hofso K, Skrubbeltrang C, Flaatten HI, Rasmussen BS, Laake JH. Spontaneous versus controlled mechanical ventilation in patients with acute respiratory distress syndrome - Protocol for a scoping review. Acta Anaesthesiol Scand. 2020 Jul;64(6):857-860. doi: 10.1111/aas.13570. Epub 2020 Mar 20.
• Laake JH, Smastuen MC, Moller MH, Larsson A, Aslam TN, Hofso K, Pham T, Fan E, Bellani G, Laffey JG; LUNG SAFE Investigators. Patient characteristics, management and outcomes in a Nordic subset of the "large observational study to understand the global impact of severe acute respiratory failure" (LUNG SAFE) study. Acta Anaesthesiol Scand. 2022 Jul;66(6):684-695. doi: 10.1111/aas.14069. Epub 2022 May 12.
• Aslam TN, Klitgaard TL, Hofso K, Rasmussen BS, Laake JH. Spontaneous Versus Controlled Mechanical Ventilation in Patients with Acute Respiratory Distress Syndrome. Curr Anesthesiol Rep. 2021;11(2):85-91. doi: 10.1007/s40140-021-00443-8. Epub 2021 Mar 3.

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): March 30, 2028

Study Registration Dates

• First Submitted: January 23, 2026
• First Submitted That Met QC Criteria: March 5, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): March 13, 2026
• Last Update Submitted That Met QC Criteria: March 11, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Acute respiratory distress syndrome; Mechanical ventilation; randomised clinical trial; Acute hypoxemic respiratory failure; controlled ventilation; feasibility trial; assisted ventilation
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Lung Diseases; Respiration Disorders; Respiratory Distress Syndrome; Respiratory Insufficiency
• Other Study ID Numbers: UTN: U1111-1335-7858

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No