Method and apparatus for a non-nutritive suck entrainment pulse generator

This document discusses, among other things, method and apparatus for a non-nutritive suck (NNS) entrainment pulse generator. An embodiment includes a valve assembly in communication with a first pressure and a second pressure to change a pressure of a baglet. A controller can switch the valve assembly to selectively couple the first and second pressures to the baglet to produce a series of pressure pulses within the baglet. In an embodiment, the pulse generator is substantially self-contained. In an embodiment, the valve assembly includes a reciprocating piston assembly to generate the series of pressure pulses. In an embodiment, the NNS entrainment pulse generator is portable.

TECHNICAL FIELD

This patent application relates generally to method and apparatus for development of infant oromotor behavior, and more particularly to method and apparatus for a non-nutritive suck entrainment pulse generator.

BACKGROUND

Sucking is a precocial motor behavior in humans. However, premature infants often demonstrate oromotor dyscoordination and are unable to suck or feed orally. This inability to feed can delay discharge from neonatal intensive care units and hinder development of coordinated oromotor behavior.

Infants' readiness to feed is often evaluated by their display of non-nutritive sucking (NNS). Typically, NNS begins between 28 and 33 weeks gestational age (GA) and is remarkably stable by 34 weeks.

The brain of a typically developing fetus includes an organized set of neurons in the brainstem and cortex that are involved in the production of centrally patterned rhythmic motor behaviors. These neural circuits are known as central pattern generators or simply “CPG's”. One such rhythmic behavior that is controlled by a CPG is the suck. Under normal circumstances, the human infant is precocial for suck, which means it is a motor behavior that is established in utero and functional at birth. An infant's ability to suck at birth is important for, among other things, getting nourishment and stimulating the infant's developing brain.

In premature birth, the premature infant loses opportunities for safe neurological development in utero. This loss can be compounded by medical complications associated with premature birth, such as strokes or hemorrhages. Further, medical complications often are treated with painful procedures which correlate with impairment in neurological development. As a result of the impairment in neurological development, the premature infant may possess grossly disorganized CPG's and therefore exhibit grossly disorganized suck, which itself can lead to other medical complications and a failure to thrive and develop. Other ramifications of disorganized suck may include: ramifications relating to the infant's overall sensorimotor development, perceptual capacity, and even delays in higher cognitive function including speech, language, and other processing skills. There is a need in the art for devices to assist development of organized suck patterns in patients exhibiting disorganized suck.

SUMMARY

The present disclosure includes apparatus and methods for a non-nutritive suck (NNS) entrainment pulse generator for developing organized non-nutritive suck in infants. In one embodiment, a NNS entrainment pulse generator includes a valve assembly in communication with a first pressure and a second pressure. A controller, coupled to the valve assembly, provides a series of pressure pulses within a baglet. The baglet may be used to entrain non-nutritive suck (NNS) of an infant. In one embodiment the first and second pressures are coupled directly to the baglet. In various embodiments, a NNS entrainment pulse generator is portable to allow for home use and to reduce patient traffic in hospitals and clinics. In an embodiment, the pulse generator includes chambers for the pressure sources and is substantially self contained to further enhance portability

In one embodiment, a non-nutritive suck entrainment pulse generator includes a reciprocating piston assembly to produce the series of pressure pulses. The reciprocating pistons are driven using the first and second pressures. In one embodiment, the reciprocating pistons are driven using a vacuum source and atmospheric pressure. In one embodiment, the reciprocating pistons are driven using a positive pressure source and atmospheric pressure. The baglet couples to the ends of a cylinder housing the pistons, The baglet expands and contracts as the pistons move away from each other, and then toward each other, respectively.

This Summary is an overview of some of the teachings of the present application and not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description. The scope of the present invention is defined by the appended claims and their legal equivalents.

DETAILED DESCRIPTION

FIG. 1shows a substantially self-contained, non-nutritive suck (NNS) entrainment pulse generator apparatus100according to one embodiment of the present subject matter. The apparatus100includes a pneumatically actuated patient therapy handpiece, or pacifier assembly103for delivering oral entrainment therapy to a patient. A controller102actuates valves in a pneumatic circuit to generate a series of positive and negative pneumatic pulses thru a tube104coupling the circuit to the pacifier assembly103. The controller102also controls a pump106connecting a vacuum, or negative pressure chamber107, and a positive pressure chamber108. The vacuum chamber and positive pressure chamber provide the pneumatic pressure sources for the pressure pulses. A vent109allows adjustment of pressure and vacuum for different therapy regiments. The vent109also allows adjustment of the system for pneumatic losses.

The nipple105, or baglet, of the pacifier assembly103, functions as an expandable membrane made from a suitable inert elastomer such as medical grade silicone. The pressure pulses expand and contract the nipple105. When the nipple of the pacifier assembly103is in a patient's mouth, the nipple's expansion and contraction is detected by a neural sensory network in the patient's lips, tongue and mouth. With regimented application of the pressure pulses, the suck central pattern generator (CPG) of the patient's brain can be modulated and subsequently entrained with an organized suck pattern. The self contained nature and portability of the apparatus expands the potential for consistent and timely success of entrainment therapy over existing therapy systems as existing therapy systems are large and cumbersome to move. The present subject matter allows therapy to be easily delivered at home, as well as, other locations remote from the traditional setting of a hospital or a clinician's office. In a hospital environment, the portability allows the equipment to be brought to the patient room reducing patient traffic thru the hospital. In some embodiments, the apparatus includes a rechargeable battery to provide power for operating the apparatus in a stand-alone mode.

FIG. 2shows a block diagram of a NNS entrainment pulse generator apparatus according to one embodiment of the present subject matter. The apparatus includes a vacuum, or negative pressure, chamber210, a pressure chamber211, a positive pulse valve212, a negative pulse valve213, a pacifier assembly214and a pump215. The vacuum210and pressure211chambers provide the pneumatic pressure sources for delivering stimulation pressure pulses to the pacifier assembly214. Each chamber is connected to the pacifier assembly through a pneumatic valve. The vacuum chamber210is connected to the pacifier assembly214through a negative pulse valve213and the positive pressure chamber211is connected to the pacifier assembly214through the positive pulse valve212. The pump215transfers gas from the vacuum chamber210to the positive pressure chamber211. With proper sizing of the respective chambers, the system becomes a substantially closed pneumatic system. As such, the transfer of gas from the vacuum chamber210into the positive pressure chamber211develops adequate vacuum and pressure to provide NNS entrainment therapy using the pacifier assembly214. The pacifier assembly214includes a pacifier216having a nipple217, or baglet, and tubing218to connect the nipple217to the pneumatic circuit of the apparatus. In various embodiments, the pacifier assembly214includes one or more pneumatic connectors219to allow easy replacement of the pacifier assembly214.

The apparatus includes a controller220to monitor the pump and valves, and sequence the pump and valves to deliver the NNS entrainment therapy. A port221connected to the controller220provides an interface to connect a computer and transfer data between the controller and the computer. In various embodiments, the controller220includes memory for recording data during application of entrainment therapy. Data recorded into the computer memory and available for exchange to a device connected to the port includes, but is not limited to, data received from various apparatus transducers, status of controller inputs and outputs, including outputs connected to the control valves, and status information native to the controller such as therapy parameters and controller status data.

Transducers are connected to the controller220to provide pressure feedback to the controller. The illustrated embodiment includes a vacuum chamber transducer222, a positive pressure chamber transducer223and one or more pacifier assembly transducers224. In various embodiments, one pacifier assembly transducer224connects to the pneumatic circuit at or near the outputs of the control valves and a second pacifier assembly transducer is connected near the pacifier of the pacifier assembly. Monitoring the two transducers can help identify pneumatic problems in the pneumatic circuit. In various embodiments, the controller is programmable and includes parameters to define maximum pressure and minimum vacuum levels for the NNS entrainment therapy pulses as well as issues with the application of the therapy. The transducers allow the controller220to control the pump215more accurately than in an open loop mode to attain adequate vacuum and pressure levels in the respective chambers and to record and monitor the delivered therapy while the therapy is applied. In various embodiments, leakage and/or changes in programmed therapy pressure levels require venting pressure from the pressure chamber211to the vacuum chamber210or exposing the vacuum chamber210to atmospheric pressure. The illustrated embodiment includes a 3-position pneumatic adjustment valve225electrically connected to the controller and pneumatically coupled to the vacuum chamber, the positive pressure chamber and the atmosphere. In a first default state (A), the valve225does not connect any of the pneumatic pathways to each other. In a second state, or valve position (X1), the valve connects the vacuum chamber210to the atmosphere. In a third state (X2), the valve connects the positive pressure chamber211to the vacuum chamber210. It is understood that other valves and valve configurations are possible without departing from the scope of the present subject matter.

Sequentially coupling the positive pressure211and vacuum210chambers to the pacifier assembly214using the positive212and negative213pulse valves applies pressure waves to the pacifier assembly214. The negative pulse valve213has two states, or valve positions. A first state (X) of the negative pulse valve213couples the vacuum chamber210to the pacifier assembly214evacuating pressure from the pacifier assembly nipple217. A second state (A) isolates the vacuum chamber210from the pacifier assembly214. The positive pulse valve212has two states, or valve positions. A first state (A) of the positive pulse valve couples the positive pressure chamber211to the pacifier assembly214inflating the pacifier assembly nipple217. A second state (X) of the positive pulse valve212isolates the positive pressure chamber211from the pacifier assembly214. It is understood that other valves and valve configurations are possible without departing from the scope of the present subject matter.

The configuration of the substantially closed, pressure pulse generator avoids issues with muffling exhaust pulses as well as the accumulation of condensation from compressing non-dehumidified room air.

Sizing of the apparatus components depends on the desired pressure, frequency and duration of the pressure pulses. For example, a system with a hand piece nipple and connecting tube with total volume less than 5 milliliters, delivering 6 pressures pulses at a frequency of 1.8 hertz and a 2 second rest pause for every 10 seconds of applied therapy and producing a change of pressure inside the nipple from atmospheric to ±100 cm H2O, requires a minimum pumping capacity of approximately 75 ml of air per minute to effect 32 positive pulses and 32 negative pulses where the maximum positive pulse pressure is approximately 2 psi. The corresponding valves and air lines are sized to provide at least 100 ml/min of gas flow assuming some efficiency loss due to flow restrictions. The corresponding valves require a minimum rise time of 10 ms to achieve the pressure increase rise time to generate impulse motion for creating neurological stimulus.

At startup, the controller220activates the pump and configures the external pneumatic circuit leading to the pacifier assembly214such that the negative pulse valve and the positive pulse valve isolate the pacifier assembly from the vacuum chamber and the positive pressure chamber until the operating vacuum and pressure are reached. The volume ratio of the two pressure reservoirs is selected such that displacement of most of the air from the vacuum chamber (˜500 mL) into the positive pressure chamber provides at least 250 cm H2O pressure (assuming that a large fraction of the air in the vacuum reservoir is transferred to the pressure reservoir ˜100 mL). A working positive pressure of ˜200 cm H2O produces and sustains the 100 cm H2O pressure maximum of the pressure pulse. The pumping capacity of the pump required is approximately 250 mL/min. In various embodiments, the pumping capacity is provided using a 12 VDC motor driven diaphragm pump. It is understood that other pump and motor configurations are possible without departing from the scope of the present subject matter.

FIGS. 3A and 3Bshow alternating pressure pulse waveforms recorded from an NNS entrainment apparatus according to one embodiment of the present subject matter.FIG. 3Ais a recording of the pressure waveform near the output of the control valves.FIG. 3Bis a recording of the pressure waveform near the pacifier assembly. Note that the sharpness of the pulses is attenuated in the waveform recorded near the pacifier assembly. The rise time of the pulses is affected by the volume of the pacifier assembly nipple and the size, shape and material of the couplings and tubing connecting the pacifier assembly to the control valves. In general, less restrictive materials and larger tubing will produce faster rise times in the waveform.

FIG. 4shows a block diagram of a NNS entrainment pulse generator450apparatus according to one embodiment of the present subject matter. The apparatus450includes a pneumatically actuated pacifier assembly451for delivering oral entrainment therapy to a patient. A controller452actuates valves to actuate a reciprocating piston assembly453to generate a series of positive and negative pneumatic pulses thru tubing454coupling the circuit to the pacifier assembly451. The control valves couple and decouple ports455on the reciprocating piston assembly to a pressure source456and a vent457to generate the pressure pulses. In various embodiments, the pressure source is a positive pressure source. In some embodiments, the pressure source is a vacuum, or negative pressure source.

FIGS. 5A and 5Bshow a NNS entrainment apparatus with a reciprocating piston pulse generator according to one embodiment of the present subject matter. The apparatus includes a pulse generator having two piston pairs531operating in a common cylinder532with 3 isolated chambers and an entrainment pacifier assembly533connected to two of the three cylinder chambers. One piston of each of the piston pairs operates in the center chamber534of the cylinder. The other piston of each piston pair operates in one of the two end chambers535,536of the cylinder. The cylinder chambers are pneumatically isolated from each other by a chamber wall537having a wiper seal about the rod connecting the pistons in each of the piston pairs. Alternating pressure pulses are generated when the piston pairs move simultaneously in opposite directions. For example, a positive pulse is generated when the piston pairs move away from each other. A negative pressure is generated as the pistons move toward each other. A controller538, with control valves539coupled to ports540,541in the center chamber of the cylinder532, sequence pressurized gas into and out of the center chamber to alternate the movement of the piston pairs for generating pressure pulses.

FIG. 5Ashows compressed gas542entering the center port540and pressurizing the area between the pistons of the first end of the two piston pairs. Simultaneously, pressure is released from the opposite side of each piston in the center chamber thru the ports541between the pistons of the first end and the walls537separating the center cylinder chamber from the end chambers. The pressurized gas forces the pistons away from each other. The movement decreases the volume of the area between the pistons at the second end of each piston pair and connected with the pacifier assembly. The decreased volume creates a positive pressure in the nipple543of the pacifier assembly.

FIG. 5Bshows compressed gas entering the end ports of the cylinder and pressurizing the area between the pistons of the first end of the two piston pairs and the walls separating the center chamber from the two end chambers of the cylinder. Simultaneously, pressure is released from the center port of the cylinder. The pressurized gas forces the pistons toward each other. The movement increases the volume of the area between the pistons at the second end of each piston pair and connected through the pacifier assembly. The increased volume eventually will create a negative pressure in the pacifier assembly as the pistons move closer together.

The above description assumes that the system, when balanced at atmospheric pressure, does not have the piston pairs positioned at an extreme limit of travel in either direction. In various embodiments, each chamber is coupled to a feedback transducer to allow closed loop control of the alternating pressure pulses during NNS entrainment therapy. Pressure and vacuum limits are determined in part from the volume of space in the pacifier assembly nipple, corresponding connection tube size and length, and the maximum pressure of the compressed gas supply. Rise and fall times for the pressure pulses are determined in part from the pneumatic flow rate of each pneumatic circuit. Positive pneumatic pressure operates the apparatus. In various embodiments, the apparatus is portable and is designed to use an existing pneumatic pressure source including, but not limited to, compressed air or gas available at many hospitals and clinics or compressed CO2available in portable canisters for home use, for example. In various embodiments, the apparatus is portable and the controller is powered for periods of time using rechargeable batteries.

FIGS. 6A and 6Bshow a NNS entrainment apparatus with a reciprocating piston pulse generator according to one embodiment of the present subject matter employing a negative pressure source. The apparatus includes a pulse generator having two piston pairs631operating in a common cylinder632with 3 isolated chambers and an entrainment pacifier assembly633connected to two of the three cylinder chambers. One piston of each of the piston pairs operates in the center chamber634of the cylinder. The other piston of each piston pair operates in one of the two end chambers635,636of the cylinder. The cylinder chambers are pneumatically isolated from each other by a chamber wall637having a wiper seal about the rod connecting the pistons in each of the piston pairs. Alternating pressure pulses are generated when the piston pairs move simultaneously in opposite directions. For example, a positive pulse is generated when the piston pairs move away from each other. A negative pressure is generated as the pistons move toward each other. A controller638, with control valves639coupled to ports640,641in the center chamber of the cylinder632, sequence pressurized gas into and out of the center chamber to alternate the movement of the piston pairs for generating pressure pulses.

FIG. 6Ashows a vacuum source642applied to the end ports641of the cylinder632, evacuating the area between the pistons of the first end of the two piston pairs631and the walls637separating the center chamber634from the two end chambers635,636of the cylinder. Simultaneously, atmospheric pressure enters the center port640of the cylinder632. The pressure differential forces the pistons away from each other. The movement decreases the volume of the area between the pistons at the second end of each piston pair and connected with the pacifier assembly633. The decreased volume creates a positive pressure, inflating the nipple643of the pacifier assembly633.

FIG. 6Bshows a vacuum source642applied to the center port640of the cylinder632and, evacuating the area between the pistons of the first end of the two piston pairs631. Simultaneously, atmospheric pressure enters the opposite side of each piston in the center chamber634thru the ports641between the pistons of the first end and the walls637separating the center cylinder chamber634from the end chambers635,636. The pressurized difference forces the pistons631toward each other. The movement increases the volume of the areas between the pistons at the second end of each piston pair. The increased volume, connected through the pacifier assembly633, creates a negative pressure in the pacifier assembly633, deflating the nipple643.

In one example a NNS entrainment pulse generator includes a baglet, a valve assembly in communication with the baglet and with a first pressure and a second pressure, the valve assembly programmable to communicate the first pressure and the second pressure to the baglet to provide pressure changes to the baglet, and a controller coupled to the valve assembly, the controller configured to produce a series of pressure pulses within the baglet.

Variations include but are not limited to, a pump coupled between a first chamber and a second chamber to adjust pressure in each chamber, a first sensor coupled to the first chamber, a second sensor coupled to the second chamber, and first and second pressure valves to couple and decoupled the first and second chambers to the baglet

Additional variations include but are not limited to a vent configured to controllably couple the first chamber with atmospheric pressure, an adjustment valve coupled between the first chamber and the second chamber to adjust pressure of the chambers, and a first transducer coupled to the controller and the baglet to sense the pressure within the baglet.

Additional variations include but are not limited to a reciprocating piston assembly comprising a cylinder and a first and second piston slideably disposed within the cylinder, wherein the first piston and the second piston are configured to move in a reciprocating motion.

Additional variations include but are not limited to a valve coupled to the cylinder and configured move the first and second pistons in the reciprocating motion. In some variations, the first pressure is atmospheric pressure. In some variations, the second pressure is positive pressure. In some variations, the second pressure is a negative pressure.

Additional variations include but are not limited to a rechargeable power supply configured to power the controller in a standalone mode and the entire apparatus being portable to reduce patient traffic in hospitals and clinics and to allow home use of a NNS entrainment pulse generator.

In one example, a method includes switching a valve assembly to a first state to generate a positive pressure pulse in a baglet, switching the valve assembly to a second state to generate a negative pressure pulse in the baglet; and repeating the switching of the valve assembly to the first state and the second state to generate a series of pressure pulses in the baglet.

Variations include but are not limited to controllably coupling a positive pressure source directly to the baglet to generate the positive pressure pulse in the baglet, controllably coupling a negative pressure source directly to the baglet to generate the negative pulse in the baglet and producing a pressure pulse waveform comprising pressure pulses having a frequency of about 1.8 Hertz.

Additional variations include but are not limited to controllably coupling a first pressure to a first port of a cylinder of a reciprocating piston assembly, controllably coupling a second pressure to a second port of the cylinder, moving the first and second pistons in a first motion, away from each other, and generating the positive pressure in the baglet using the first motion of the first and second pistons.

Additional variations include but are not limited to controllably coupling the first pressure to the second port of the cylinder, controllably coupling the second pressure to the first port of the cylinder, moving the first and second pistons in a second motion, toward each other, and producing the negative pressure in the baglet using the second motion of the first and second pistons.

Additional variations include but are not limited to controllably coupling a positive pressure to the first port, and controllably coupling a negative pressure to the second port.

Other variations exist and those set forth are intended to demonstrate the present subject matter, but are not exhaustive or exclusive.

This application is intended to cover adaptations and variations of the present subject matter. It is to be understood that the above description is intended to be illustrative, and not restrictive. The scope of the present subject matter should be determined with reference to the appended claims, along with the full scope of legal equivalents to which the claims are entitled.