Prone Positioning During High Flow Oxygen Therapy in Acute Hypoxemic Respiratory Failure (Optiprone)
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ClinicalTrials.gov Identifier: NCT03095300 |
Recruitment Status :
Completed
First Posted : March 29, 2017
Last Update Posted : August 3, 2022
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Background High-flow nasal cannula (NHF) are a promising tool for administering oxygen to critically ill patients with high respiratory demand.
Prone positioning (PP) is a simple and cost-effective strategy that since 1980s has been used in mechanically ventilated patients with acute respiratory failure to treat oxygenation impairment.
A large randomized study detected a relevant survival benefit by prone positioning in patients with moderate to severe acute respiratory distress syndrome (ARDS) undergoing invasive mechanical ventilation and managed with the ARDS network PEEP-FiO2 table strategy.
Theoretically, PP may benefit spontaneous breathing patients too, but data concerning its application in such context are limited to small case series and a retrospective study.
The investigators designed a pilot feasibility study to assess the safety and efficacy of prone positioning in acute hypoxemic respiratory failure patients noninvasively treated with NHF.
Methods Patients: 15 adult hypoxemic (PaO2/FiO2<200 mmHg with respiratory rate greater than 25 breaths per minute) non-hypercapnic patients with acute respiratory failure. PaO2/FiO2 will be assessed while the patients is receiving 50 L/min of 50% oxygen via a standard face mask for a 15-minute monitoring period at study entry.
Protocol Eligible patients will undergo NHF for 1 hour in the supine semi-recumbent position (baseline, BL).
Afterwards, each enrolled patient will be placed in the prone position for 2 hours.
After a 2-hour PP period, the patient will be rotated and will undergo 1 hour of NHF in the semi recumbent supine position (Supine step).
Measurements Patient's demographics will be collected at study entry.
At the end of the monitoring period, and then on a hourly basis the following data will be collected:
- Respiratory rate, SpO2, pH, PaCO2, PaO2, SaO2, PaO2/FiO2;
- Heart Rate, arterial blood pressure;
- Dyspnea, as defined by the VAS dyspnoea scale;
- Discomfort, as defined by a visual analogic scale (VAS) adapted to rate the procedural pain of ICU patients;
- End expiratory lung impedance (EELI), tidal volume distribution, global and regional lung dynamic strain (Change in lung impedence due to tidal volume/ELLI).
- Work of breathing, assessed by pressure-time product (PTP) of the esophageal pressure and inspiratory swings in this signal.
- Occurrence of pendelluft phenomenon
The number of adverse events will be also recorded for each study step.
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Respiratory Failure With Hypoxia Respiratory Failure Without Hypercapnia | Procedure: Prone position | Not Applicable |

Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 15 participants |
Allocation: | N/A |
Intervention Model: | Single Group Assignment |
Intervention Model Description: | Each enrolled patient will be monitored in the supine position for one hour, placed in the prone position for two hours and re-placed in the supine position for a final 1-hour step |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | Prone Positioning During High Flow Oxygen Therapy in Patients With Acute Hypoxemic Respiratory Failure: a Pilot Physiological Trial |
Actual Study Start Date : | October 1, 2018 |
Actual Primary Completion Date : | June 20, 2020 |
Actual Study Completion Date : | December 20, 2020 |

- Procedure: Prone position
Patients are rotated from the supine to the prone position for a period of 2 hours.
- Number of patients that undergo 2 hours of prone positioning without showing serious adverse events [ Time Frame: 2 hours ]
Number of patients that tolerate the procedure and complete the study according to the protocol without serious adverse events. The following will be considered serious adverse events:
- Oxygen desaturations (SpO2 <90%)
- Episodes of haemodynamic instability (Systolic arterial pressure<80 mmHg or FC>120 BPM)
- Displacement of central venous line, if documented
- Displacement of arterial line, if documented
- Oxygenation [ Time Frame: 2 hours ]Effects of prone position on oxygenation, defined by PaO2/FiO2 ratio
- Respiratory rate [ Time Frame: 2 hours ]Effects of prone position on respiratory rate
- Comfort [ Time Frame: 2 hours ]Effects of prone position on comfort, defined according a visual analog comfort scale
- Dyspnoea [ Time Frame: 2 hours ]Effects of prone position on dyspnoea, defined according Borg dyspnea scale
- Global impedance-derived End-expiratory lung volume [ Time Frame: 2 hours ]Effects of prone position on End-expiratory lung volume, measured with electrical impedance tomography
- Regional impedance-derived End-expiratory lung volume [ Time Frame: 2 hours ]Effects of prone position on End-expiratory lung impedance in the four regions of the lungs (ventral, mid-ventral, mid-dorsal, dorsal), measured with electrical impedance tomography
- Tidal volume distribution [ Time Frame: 2 hours ]Effect of prone position on % tidal volume distribution in the four regions of the lung (ventral, mid-ventral, mid-dorsal, dorsal), explored with electrical impedance tomography
- Global impedance-derived lung dynamic strain [ Time Frame: 2 hours ]Change in impedance due to tidal volume / end expiratory lung impedance, both measured with electrical impedance tomography
- Regional impedance-derived lung dynamic strain [ Time Frame: 2 hours ]Change in impedance due to tidal volume / end expiratory lung impedance in the four regions of the lungs (ventral, mid-ventral, mid-dorsal, dorsal), measured with electrical impedance tomography
- Inspiratory effort [ Time Frame: 2 hours ]The esophageal pressure swings during inspiration
- Respiratory mechanics [ Time Frame: 2 hours ]Respiratory system, lung and chest wall mechanics
- Pendelluft [ Time Frame: 2 hours ]Occurrence of intra-tidal shift of gas within different lung regions at beginning of inspiration
- Work of breathing [ Time Frame: 2 hours ]Pressure-time product of the esophageal pressure
- Nurse workload [ Time Frame: 5 hours ]The nurse in charge will be asked to anonymously rate in minutes the additional workload due to the entire procedure (both proning and unproning)
- Feasibility scale [ Time Frame: 5 hours ]At the end of the study, the nurse in charge will be asked to anonymously judge the feasibility of the procedure using an analog scale ranging from 0 (completely unfeasible) to 10 (totally feasible)
- Safety scale [ Time Frame: 5 hours ]At the end of the study, the nurse in charge will be asked to anonymously to judge the safety of the procedure using an analog scale ranging from 0 (completely unsafe) to 10 (totally safe)
- Prone-position related serious adverse events [ Time Frame: 2 hours ]
Composite outcome, any of the following included:
- Oxygen desaturations (SpO2 <90%)
- Episodes of haemodynamic instability (Systolic arterial pressure<80 mmHg or FC>120 BPM)
- Displacement of central venous line, if documented
- Displacement of arterial line, if documented
- Prone-position related adverse events [ Time Frame: 2 hours ]
Composite outcome, any of the following included:
- Displacement of peripheral venous line, if documented
- Displacement of urinary catheter, if documented
- Displacement of oro- or naso-gastric tube, if documented
- Displacements of the nasal cannula, if any

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Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Respiratory rate>25 bpm and <40 bpm.
- PaO2/FiO2<200 mmHg measured after 15 minutes of heated and humidified 50% oxygen at a rate of 50 l/min via a non-rebreathing face mask. Given the use of the high flows, nominal FiO2 will be considered a reliable estimate of the actual one.
- PaCO2 <45mmHg
- Absence of history of chronic respiratory failure or moderate to severe cardiac insufficiency (NYHA > II or left ventricular ejection fraction <50%).
- Body mass index <30 kg/m2
- Absence of any contraindication to prone position.
- Written informed consent
Exclusion Criteria:
- Exacerbation of asthma or chronic obstructive pulmonary disease (COPD);
- Chest trauma
- Cardiogenic pulmonary oedema;
- Severe Neutropenia (<500 WBC/mm3);
- Haemodynamic instability (Systolic blood pressure <90 mmHg or mean arterial pressure <65 mmHg) and/or lactic acidosis (lactate >5 mmol/L) and/or clinically diagnosed Shock
- Metabolic Acidosis (pH <7.30 with normal- or hypo-carbia);
- Chronic kidney failure requiring dialysis before ICU admission;
- Glasgow coma scale <13;
- Vomiting and/or upper gastrointestinal bleeding.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03095300
Italy | |
General ICU, A. Gemelli hospital | |
Rome, Italy, 00100 |
Principal Investigator: | Massimo Antonelli, MD | Catholic University of the Sacred Heart |
Responsible Party: | Massimo Antonelli, MD, Full Professor, Director of the Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart |
ClinicalTrials.gov Identifier: | NCT03095300 |
Other Study ID Numbers: |
Optiprone |
First Posted: | March 29, 2017 Key Record Dates |
Last Update Posted: | August 3, 2022 |
Last Verified: | August 2022 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Undecided |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Product Manufactured in and Exported from the U.S.: | No |
Prone Position High-flow oxygen therapy |
Respiratory Insufficiency Hypoxia Hypercapnia |
Respiration Disorders Respiratory Tract Diseases Signs and Symptoms, Respiratory |