Abstract:
The invention concerns a combination control for use in nasal cannula therapy, and includes a high flow, nasal cannula respiratory assistance ducted system.

Description:
This regular application is based on provisional application No. 60/850,410, filed Oct. 10, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to nasal cannula therapy, and more particularly to improvements concerning fluid flow in nasal cannula therapy systems. 
     Nasal continuous positive airway pressure, NCPAP, is a used standard for administration of non-invasive positive airway pressure in the Neonate. Historically, Nasal Cannulae have been used at low flow rates (&lt;1.5 1 pm) during infant weaning from assisted ventilation, or for maintenance in the sub-acute phase of chronic lung disease. Difficulty in regulation of pressure, and concerns regarding the damaging effects of inadequately warmed and humidified oxygen delivery systems on nasal mucosa, precluded the use of these devices in the more acute phases of respiratory distress and at the higher liter flow rates that would have been required to generate the pressures necessary to provide for that particular disease process. Certain devices held the promise of improved humidification and warming of the cannula flow, but introduced the possible deleterious effect of unknown pressure propagation as well as reported bacteria contamination of the circuit. 
     Accordingly, there was concern about delivering pressures that were excessive and possibly damaging to the respiratory tract, sinuses, ear drum or GI tract. Mechanical ventilators used for monitoring for pressures and flow were excessively expensive to supply and operate. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide solutions to the described problems and difficulties. Basically, the invention is embodied in a combination control including monitoring for use in nasal cannula therapy, that comprises: 
     a) a high flow, nasal cannula respiratory assistance ducted system, 
     b) the system including the following ii) means and at least one or both of the following i) means and iii) means,
         i) flow metering first means associated with said system ducting, upstream of the nasal cannula,   ii) safety pressure release valve second means also associated with said system ducting, downstream of the nasal cannula,   iii) flow metering third means associated with the system ducting, and downstream of the nasal cannula.       

     Another object of the invention includes provision, and in series sequence, of:
         i) an oxygen gas source,   ii) means receiving oxygen from said source, and air, for blending air, oxygen, and/or nitric oxide, in an output stream,   iii) a heater/humidifier to heat and humidify said stream,   iv) a nasal cannula to receive the heated and humidified stream, for administration to the infant or patient.       

     A further object includes provision of a bypass outlet from the system for flow to the patient, downstream of said first means. 
     Yet another object includes provision of a proportioning valve extending at a system outlet, and operating as said second means. 
     Another object of the present invention is to provide for requisite warmth and humidification of the air stream. The complications of inadvertent pressure propagation are avoided. NCPAP is not needed for pressure regulation. Flow regulation occurs without attendant pressure effects. The device allows for demand flow without using a conventional ventilator and subsequent costs. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
    
    
     
       DRAWING DESCRIPTION 
         FIG. 1  is a system diagram; 
         FIG. 2  is a system block diagram; 
         FIG. 3  is a perspective view showing actual elements of the system; 
         FIG. 4  is a section taken through a pressure relief flutter type valve, in a system; 
         FIG. 5  is a view showing system ducting, a pressure relief valve in series in the ducting; and a flow meter downstream of the pressure relief valve; 
         FIG. 6  is a view showing system ducting, a pressure relief valve in series in the ducting, and a flow meter upstream of cannula in the ducting; and 
         FIG. 7  is a view like  FIG. 6 , but also showing an additional flow meter downstream of the pressure relief valve. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIG. 1 , showing a preferred system, air supplied at  10 , and oxygen supplied at  100  enter a blending zone  12 , to be thoroughly mixed or blended. A control  11  to increase or decrease flows from the oxygen supply  100  is shown. The flowing mix passes to a flow meter at  16  via a warmer/humidifier  15 , which may consist of warm water into which the flow is injected to bubble up and continue flowing as at  17 , as warmed, humidified air/oxygen blend. Some of the flow passes to the small tubes or prongs  14  for supply to the infant&#39;s lungs. Some of that supply may variably leak to atmosphere, via the nostrils or expelled via the infant&#39;s mouth, for example along with flow expelled from the lungs, during breathing. Flow pressure supplied to the cannula is desirably below about 10 cm water pressure. The oxygen supply, as at hospital wall outlet  100 , is typically about 50 psi (3,154 cm/H 2 0). 
     Remnant air passes in duct  20   FIG. 4  to an outlet, such as a “pop-off” valve. The latter preferably takes the form of a proportioning valve, seen at  21   a  in  FIG. 4 , and having elastomeric flow control sections  21   b  that excessive air pressure forcibly spread apart, for example to suddenly discharge the flow when the pressure exceeds about 10 cm water pressure. See also arrow  23 , indicating discharge to atmosphere. Need for means to maintain pressure in the duct at or near 10 cm of water derives from the infant&#39;s lungs, which should not be subjected to excessive pressure. Such excessive pressure could arise as from closing of the infant&#39;s mouth or covering of its nostrils, or both, excessive pressure being variably transmitted to  21   a . Proportioning valve  21  or  21   a  is herein designated at times as a form of pressure relief “second means”. 
     The invention also contemplates provision and operating of flow metering third means, indicated at  28  in  FIGS. 1 and 5 , downstream of the cannula  14 , and downstream of the second means  21   a ; and/or provision and operation of flow metering first means, indicated at  32  in  FIG. 6 , in the ducting upstream of the nasal cannula  14 .  FIG. 7  shows use of both  28  and  32  in the system ducting. These elements typically have visible flow rate readouts, at the sides of transparent tubing  28   a  and  32   a , containing pistons  28   b  and  32   b  which shift position lengthwise in the tubing, as flow rates vary, to indicate such rates. Air flow pressure pushes such pistons against compression springs  28   c  and  32   c . If indicated flow at  28  shows loss of flow at  14 , the flow at  11  can be adjusted to compensate for the loss to atmosphere at  21   a , consistent with the infant&#39;s or patient&#39;s lungs. Such indicated rates, prior to adjustment, could for example be too low as a result of excessive leaking at the infant&#39;s nostrils or mouth. 
       FIG. 3  shows the ducting to include plastic tubing  40  forming a loop  41 , as a result of a clasp  42  loosely grasping tubing portions  40   a  and  40   b  permitting relative slippage to contract or enlarge the loop, around the infant&#39;s head, for holding cannula prongs  14  in the nostrils. Note inclusion of the proportioning valve enclosure  46 , in series with the tubing. Fixture  47  connects the tubing to system ducting downstream of the heater humidifier  15 . 
       FIG. 2  is a block diagram of the system.