Retention of airway secretions is a frequent complication in critically ill patients requiring invasive mechanical ventilation (MV).This complication is often due to excessive secretion production and ineffective secretion clearance.
Mechanical insufflator-exsufflator (MI-E) is a respiratory physiotherapy technique that aims to assist or simulate a normal cough by using an electro-mechanical dedicated device. A positive airway pressure is delivered to the airways, in order to hyperinflate the lungs, followed by a rapid change to negative pressure that promotes a rapid exhalation and enhances peak expiratory flows.
However, there is no consensus on the best MI-E settings to facilitate secretion clearance in these patients. Inspiratory and expiratory pressures of ±40 cmH2O and inspiratory-expiratory time of 3 and 2 seconds, respectively, are often used as a standard for MI-E programming in the daily routine practice, but recent laboratory studies have shown significant benefits when MI-E setting is optimized to promote an expiratory flow bias.
The investigators designed this study to compare the effects of MI-E with an optimized setting versus a standard setting on the wet volume of suctioned sputum in intubated critically ill patients on invasive MV for more than 48 hours.
Adults (> 18yo).
Endotracheal intubation and invasive mechanical ventilation for > 48h and active humidification for > 24h.
Richmond Agitation-Sedation Scale -3 to -5.
Signed informed consent.
Patients with hemodynamic instability (MAP < 60 or > 110, Heart Rate < 50 or > 130, new onset arrhythmias), respiratory instability (PEEP > 12cmH2O, SpO2 < 90% or fraction of inspired oxygen (FiO2) > 60%).
Undrained pneumothorax/pneumomediastinum.
Unstable intracranial pressure (ICP > 20mmHg or MAP < 60).
Severe bronchospasm.
Crossover
MI-E Intervention protocol
DeviceThe endotracheal tube cuff will be inflated to 40 cmH2O and MI-E device will be used to deliver MI-E in automatic mode, with 4 sets of 5 respiratory cycles each and a 1-minute interval between each set. Before initiation of the MI-E intervention protocol, the investigators will carry out a short-period test to find the appropriate MI-E settings to achieve inspiratory volumes of ≥1 liter and PEF ≥80 L/min. Concretely, inspiratory and expiratory time will always be set at 4 seconds and 2 seconds, respectively, and inspiratory flow will always be in slow mode. Once the appropriate inspiratory pressure will be found, the expiratory pressure will be initially set to exceed in 30 cmH2O the inspiratory pressure and, if required, this will be increased by 5 cmH2O until achieving a PEF ≥80 L/min with a maximum expiratory pressure of 70 cmH2O.
Standard MI-E setting
DeviceCough Assist E70 device (Philips Respironics, USA, Andover, Massachusetts) will be used to deliver MI-E in automatic mode, with 4 sets of 5 respiratory cycles each and a 1-minute interval between each set. During the 1-minute pause between sets, the patient will be reconnected to the ventilator to avoid desaturation and de-recruitment during procedures. PEEP will remain stable during the protocol. The standard MI-E setting will consist of in-expiratory pressures of +40/-40 cmH2O, medium inspiratory flow, with 3 seconds and 2 seconds of in-expiratory time, respectively, and 1-second pause.
Wet volume of sputum
Airway suctioning will be carried out using an open aspiration procedure, using a 12French catheter connected to a sterile collection container. The suction procedure will be performed according to international guidelines . If necessary, 5 ml of saline solution will be used to rinse the catheter in case of impacted secretions inside the catheter; later this volume will be subtracted from the final volume of secretions, thus obtaining the exact amount of wet sputum.
Respiratory parameters: Inspiratory flow (PIF)
Flow will be measured with a heated pneumotachograph (Fluxmed GrH monitor MBMED, Buenos Aires, Argentina) inserted between the proximal tip of the endotracheal tube and the Y-piece of the breathing circuit. All signals will be recorded on a personal computer for subsequent analysis with dedicated software (FluxReview software MBMED, Buenos Aires, Argentina)
Respiratory parameters: Peak expiratory flow (PEF)
Flow will be measured with a heated pneumotachograph (Fluxmed GrH monitor MBMED, Buenos Aires, Argentina) inserted between the proximal tip of the endotracheal tube and the Y-piece of the breathing circuit. All signals will be recorded on a personal computer for subsequent analysis with dedicated software (FluxReview software MBMED, Buenos Aires, Argentina)
Respiratory parameters: difference between PEF-PIF;
Flow will be measured with a heated pneumotachograph (Fluxmed GrH monitor MBMED, Buenos Aires, Argentina) inserted between the proximal tip of the endotracheal tube and the Y-piece of the breathing circuit. All signals will be recorded on a personal computer for subsequent analysis with dedicated software (FluxReview software MBMED, Buenos Aires, Argentina)
Respiratory parameters: PEF:PIF ratio
Flow will be measured with a heated pneumotachograph (Fluxmed GrH monitor MBMED, Buenos Aires, Argentina) inserted between the proximal tip of the endotracheal tube and the Y-piece of the breathing circuit. All signals will be recorded on a personal computer for subsequent analysis with dedicated software (FluxReview software MBMED, Buenos Aires, Argentina)
Demographic variables: Age
Age will be collected from the medical record. Age, gender, weight, BMI, height, days of intubation and reason for ICU admission will be collected from the medical record at patient's inclusion.
Demographic variables: Gender
Gender will be collected from the medical record. Age, gender, weight, BMI, height, days of intubation and reason for ICU admission will be collected from the medical record at patient's inclusion.
Demographic variables: Weight
Weight (kilograms) will be collected from the medical record. Age, gender, weight, BMI, height, days of intubation and reason for ICU admission will be collected from the medical record at patient's inclusion.
Demographic variables: BMI
BMI (kg/m\^2) will be collected from the medical record. Age, gender, weight, BMI, height, days of intubation and reason for ICU admission will be collected from the medical record at patient's inclusion.
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