Prone Positioning During High Flow Oxygen Therapy in Patients With Acute Hypoxemic Respiratory Failure: a Pilot Physiological Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Enrollment
- 15
- Locations
- 2
- Primary Endpoint
- Number of patients that undergo 2 hours of prone positioning without showing serious adverse events
Study Overview
Brief Summary
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.
Detailed Description
Background Nasal high flow oxygen (NHF) is a new and promising tool for oxygen therapy in critically ill patients: NHF allows accurate delivery of the set FiO2, anatomical dead space clearance due to a washout effect in the upper airways and provides a small, variable amount of positive end end-expiratory pressure. Different studies have investigated its safety and efficacy in several clinical setting and, recently, a randomized controlled trial showed that NHF, as compared to NIV, may reduce the intubation rate in severely hypoxemic patients with de novo acute respiratory failure (AHRF).
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. In the acute respiratory distress syndrome (ARDS) PP reduces intrapulmonary shunt (Qs/Qt) and enhances lung recruitment, modifying both lung ventilation (VA) and lung perfusion (Q) distribution, finally generating an improvement in VA/Q matching and reversing oxygenation impairment. In addition, the reduction of transpulmonary gradient (mean pulmonary arterial pressure-pulmonary artery occlusion pressure) due to a higher pulmonary arterial occlusion pressure allows pulmonary vascular recruitment, possibly lowering dead space fraction. Indeed, prone positioning sessions have been shown to reduce right ventricular afterload, increase cardiac index in subjects with preload reserve and reverse acute cor pulmonale in severe ARDS patients. Finally, 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 benefits may concern also spontaneous breathing patients, in whom it could possibly contribute to the success of the noninvasive strategy. Data concerning PP application in such context are limited to small case series and a retrospective study involving patients undergoing NIV or oxygen therapy and suggesting good patients tolerance, significant improvement in oxygenation during the procedure and no increase in nurse workload. In particular, in the retrospective study by Pesenti and co. 43 procedures in 15 patients were analysed: three patients (20%) received mild sedation without dosing adjustments over the course of the study, median [IqR] duration of prone positioning was 3[2-4] hours and only in two cases (5%) pronation had to be interrupted after 30 minutes due to patient's discomfort, while no other respiratory or technical complications, such as displacement of indwelling catheters, facial oedema, pressure sores, pressure neuropathies, compression of nerves, and retinal vessels or vomiting, have been documented. Given its high tolerability, simplicity to use and positive effect on patients' comfort when compared both to NIV and to low flow oxygen delivered through a face mask, NHF may be the optimal strategy for the respiratory management of spontaneous breathing patients during prone positioning.
Interestingly, a recent electrical impedance tomography study on 20 healthy volunteers during NHF showed a more homogeneous dorsal-to-ventral ventilation pattern in PP, as compared to the supine position: notably, a dorsal-to-ventral more uniform air distribution may benefit hypoxemic patients, given that PaO2 response to oxygen supplementation can be fostered by more homogeneous regional lung inflation and better oxygenation has been shown to be a predictor of NHF treatment success.
The investigators designed a pilot feasibility study to assess the safety and efficacy of prone positioning in patients wit AHRF undergoing high flow oxygen therapy via nasal cannula.
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- 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.
Outcomes
Primary Outcomes
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
Secondary Outcomes
- Respiratory rate(2 hours)
- Comfort(2 hours)
- Dyspnoea(2 hours)
- Global impedance-derived End-expiratory lung volume(2 hours)
- Regional impedance-derived End-expiratory lung volume(2 hours)
- Tidal volume distribution(2 hours)
- Global impedance-derived lung dynamic strain(2 hours)
- Regional impedance-derived lung dynamic strain(2 hours)
- Inspiratory effort(2 hours)
- Respiratory mechanics(2 hours)
- Pendelluft(2 hours)
- Work of breathing(2 hours)
- Nurse workload(5 hours)
- Feasibility scale(5 hours)
- Safety scale(5 hours)
- Prone-position related serious adverse events(2 hours)
- Prone-position related adverse events(2 hours)
Investigators
Massimo Antonelli
MD, Full Professor, Director of the Department of Anesthesiology and Intensive Care Medicine
Catholic University of the Sacred Heart