This invention relates to patient airway management systems such as ventilation catheters, which are commonly known as endotracheal tubes, and supraglottic airway systems such as laryngeal masks and the like.
The traditional field of airway management includes a process of controlled ventilation that usually uses a mechanical ventilating machine to deliver a predetermined amount of inspiratory fluid, which is usually an air/oxygen gas mixture, with or without added water vapor, to the lungs of a patient on a predetermined cycle. Usually, the ventilating machine cycles between delivering relatively high-pressure inspiratory fluid via a delivery system to the patient's lungs for a short time, and then reducing the pressure in the delivery system for a short time so that used inspiratory fluid within the patient's lungs is expelled. The ventilating machine repeats this cycle of delivering new inspiratory fluid to and then expelling used inspiratory fluid from a patient's lungs, thereby ensuring proper oxygenation of a patient during times when they are unable to breathe on their own.
More recently, airway management systems have evolved to permit oxygenation of a patient using oxygenated liquids and/or using a non-cyclic process involving a continuous flow of oxygenated liquids to a patient's lungs while simultaneously maintaining a continuous flow of used fluids from the patient's lungs. An example of these types of systems can be found in U.S. Pat. No. 5,706,830 to Parker.
Patient airway management structures such as ventilation catheters and supraglottal-positioned airway structures are commonly used by both traditional and these more recent airway management systems to deliver inspiratory fluid to the patient's lungs. Inspiratory fluid is usually delivered to these structures through a single tube, the internal cavity of which is often referred to as a lumen, that has an open distal end. The distal end is inserted through a patient's mouth and in cases where the structure is a catheter, inserted into the patient's trachea so that the distal end is positioned well past the patient's vocal chords. The opposite end of the endotracheal tube is operably connected to a ventilation machine. Accordingly, inspiratory fluid is provided directly to the lungs through the endotracheal tube and used fluid is removed from the patient's lungs through the same tube.
The endotracheal tube must have a reasonably small cross-section to permit easy insertion and positioning of the tube within a patient's trachea. However, the cross-section must be large enough to allow a sufficient flow of oxygenated fluid therethrough.
To date, efforts to improve the use and operation of endotracheal tubes have focused on solving two problems. First, efforts have focused on improving the security and pneumatic sealing of the endotracheal tube within the trachea. Second, efforts have focused on improving the ability of the endotracheal tube to pneumatically isolate individual lungs and/or bronchial chambers within a lung.
Regarding the first problem, one solution that addresses this issue has been to place an inflatable cuff around the endotracheal tube toward the distal end of the tube. The cuff is deflated during insertion of the tube, and inflated when the tube is properly positioned within the trachea, thereby holding the tube in place and creating a pneumatic seal. An example of these types of cuff structures can be found in FIGS. 1A and 1B of U.S. Pat. No. 6,443,156 to Niklason et al.
While the seal offered by these cuffs reduces the likelihood of a patient's airway being inadvertently contaminated with gastric and pharyngeal fluids, they also seal within a patient's lungs pulmonary secretions and fluids. A typical patient can produces about 200 cubic centimeters to 400 cubic centimeters of pulmonary secretions and fluids a day. The volume of these fluids and secretions tends to increase dramatically if a patient also has a pulmonary infection and/or certain types of cardiac disease.
The usual methods for addressing pulmonary secretion and fluid build-up arising during mechanical ventilation of a patient involve periodic suctioning of the patient's lungs and/or an increased antibiotic treatment to address ancillary infections that arise. Such periodic suctioning increases the risk of damaging a patient's pulmonary system and increases the risk of contaminating a patient's airway during each procedure.
Regarding the second problem, some inventors have attempted to isolate lungs and/or bronchial chambers by providing a plurality of individual lumens within the endotracheal tube. Each tube can have its own pneumatic cuff to allow isolation of particular lungs and/or bronchial tubes. However, each tube operates much like a single lumen tube, by providing both inspiratory fluid to the lung and removing used inspiratory fluid from the lung. These types of structures still allow pulmonary secretions and fluids to build-up in the lungs, and the traditional secretion removal and treatment methods must still be employed. Moreover, the cross section of the endotracheal tube can be rather large, thereby limiting the usefulness of the tube in small airways, such as on children and infants.
More recently, supraglottic-positioned airway structures have been developed. One such structure is commonly referred to as a laryngeal mask. It usually has an inflatable mask and resilient tube that connects to the inspiratory fluid delivery system. The mask is inserted in the patient's pharynx, forming a low pressure seal around the laryngeal inlet thereby permitting positive pressure ventilation. Exemplar laryngeal mask structures can be found in U.S. Pat. No. 7,140,368 to Collins and U.S. Pat. No. 5,632,271 to Brain, the disclosures of which are hereby incorporated by reference.
A similar structure can be found in U.S. Pat. No. 5,819,733 to Bertram, which is hereby incorporated by reference. It discloses a transpharyngeal-positioned inspiratory fluid delivery tube with pharyngeal and esophageal inflatable cuffs positioned therealong. Once the tube is inserted into the patient's esophagus, the esophageal cuff is inflated to isolate the patient's gastric system. Then the pharyngeal cuff is inflated within the patient's pharynx, thereby isolating the patient's airway to the inspiratory fluid delivery tube.
Despite the benefits of these supraglottic-mounted airway structures, they still have similar drawbacks to those found in conventional endotracheal tubes. For example, they do not effectively remove pulmonary fluids and debris from the patient's airway.