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Publication Number
US-9474469-B2
Publication Date
2016-10-25
Expiration Date
Abstract
A method of monitoring tracheal pressure of a subject is disclosed. The subject is ventilated with breathing gas flowing via an endotracheal tube having an inflatable cuff. The method comprises monitoring sealing of the trachea by the cuff using a close loop control, varying a ventilation pressure thereby varying flow level of the breathing gas, monitoring a response pressure within the cuff in response to the variation, and calculating the tracheal pressure using the ventilation pressure variations, the cuff response pressure and the flow level. In some embodiments, an under-pressure is applied for suctioning fluid carrying secretions, synchronously with variations in the tracheal pressure.
Core Innovation
The invention provides a method of monitoring tracheal pressure of a ventilated subject using an endotracheal tube having an inflatable cuff. The method monitors sealing of the trachea by controlling a baseline pressure within the cuff using close loop control to generally minimize the baseline pressure while ensuring sealing. A variation is applied to a ventilation pressure to vary a flow level of the breathing gas, and variation in a peak above the baseline of a pressure pulse within the cuff is monitored responsively to the variation of the ventilation pressure.
A ratio is calculated between the monitored variation in the peak and the applied ventilation pressure variations, and the tracheal pressure is calculated using the calculated ratio. The method further suctions secretions from the endotracheal tube in synchronization with the monitored tracheal pressure. In another arrangement, the tracheal pressure is calculated by determining obstruction level of the endotracheal tube, an effective internal radius based on the obstruction level, and a pressure drop resulting from the effective internal radius.
The invention further integrates sealing monitoring and secretion management by measuring a level of at least one measure indicative of leakage of secretion past the cuff to the lungs and adjusting inflation of the cuff based on the measured level to generally minimize leakage while minimizing pressure associated damages to the trachea. In some implementations, at least one identifiable additive is delivered through the endotracheal tube and a level of the identifiable additive is monitored at a monitoring location in the subject’s body to adjust cuff inflation.
Claims Coverage
The provided material includes five independent claims. Across these claims, the core coverage centers on close loop cuff baseline control, applying ventilation pressure variation, monitoring a peak above baseline of a cuff pressure pulse, and calculating tracheal pressure via a ratio or via pressure drop derived from an obstruction/radius model, with suction synchronized to the monitored tracheal pressure when included.
Monitoring tracheal pressure using cuff baseline close loop control and peak ratio
A method monitoring sealing of the trachea by controlling a baseline pressure within an inflatable cuff using close loop control, applying variation to ventilation pressure to vary flow level, monitoring variation in a peak above the baseline of a pressure pulse within the cuff responsively to the ventilation pressure variation, calculating a ratio between the monitored peak variation and the applied ventilation pressure variations, and calculating the tracheal pressure using the calculated ratio.
Synchronization of secretion suction to monitored tracheal pressure
The method further suctioning secretions from the endotracheal tube in synchronization with the monitored tracheal pressure.
Obstruction-based pressure drop computation for tracheal pressure
Calculating obstruction level of the endotracheal tube based on the calculated ratio, calculating an effective internal radius of the endotracheal tube based on the obstruction level, calculating a pressure drop resulting from the effective internal radius, and calculating the tracheal pressure using the pressure drop.
System for calculating tracheal pressure from cuff peak variation ratio
A system including a cuff inflating unit, a controller for adjusting cuff inflation to provide a minimal cuff inflation pressure sufficient to ensure sealing and for applying variation to ventilation pressure and flow level, a pressure sensor sensing pressure within the cuff to monitoring variation in a peak above a baseline of a pressure pulse responsive to ventilation pressure variation, and a tracheal pressure calculator calculating a ratio between the monitored peak variation and the applied ventilation pressure variations and calculating the tracheal pressure using the calculated ratio.
Leakage-indicative sealing monitoring and cuff inflation adjustment
Measuring a level of at least one measure indicative of leakage of secretion past the cuff to the lungs, and adjusting inflation of the cuff based on the level to generally minimize leakage of secretion from above the cuff to the lungs while minimizing pressure associated damages to the trachea.
Identifiable additive delivery with ratio-based tracheal pressure monitoring
Delivering at least one identifiable additive through the endotracheal tube in a method that monitors sealing by controlling a baseline pressure within the cuff using close loop control, applies variation to ventilation pressure, monitors variation in a peak above the baseline of a pressure pulse within the cuff responsively to the ventilation pressure variation, calculates a ratio between the monitored peak variation and the applied ventilation pressure variations, and calculates the tracheal pressure using the calculated ratio.
Across the independent claims, the main inventive features are the closed-loop control of cuff baseline pressure to ensure sealing while minimizing baseline, the application of ventilation pressure variation to create cuff pressure pulse peaks, the computation of tracheal pressure from a ratio involving the peak above baseline and the ventilation pressure variations, and, when included, the synchronization of secretion suctioning to the monitored tracheal pressure. Additional independent-claim coverage includes deriving tracheal pressure from obstruction level, effective internal radius and pressure drop, monitoring leakage via leakage-indicative measures to adjust cuff inflation, and optionally delivering identifiable additive(s) through the endotracheal tube.
Stated Advantages
Generally minimizes the baseline pressure while ensuring sealing.
Generally minimizes leakage of secretion from above the cuff to the lungs.
Minimizes pressure associated damages to the trachea.
Enables suctioning secretions in synchronization with the monitored tracheal pressure.
Documented Applications
Ventilated subjects using an endotracheal tube with an inflatable cuff, where tracheal pressure is monitored and secretions are suctioned in synchronization with the monitored tracheal pressure.
Monitoring sealing of the trachea and adjusting cuff inflation based on leakage of secretion past the cuff to the lungs to minimize leakage and pressure associated damages to the trachea.
Delivery of at least one identifiable additive through the endotracheal tube and monitoring a level of the identifiable additive at a monitoring location to adjust cuff inflation.
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