Abstract:
An improved Automated Arterial Pressure Regulating Device wherein said device shall have the means to infuse a vasopressor and/or a vasodilator at user determined rates as well as allow the device to automatically maintain a user determined arterial pressure. Auto regulation of pressure is assisted by means of a physiologic balance indicator and Warnings, Cautions, and Advisories in the Alerts area of the display screen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    PCT application number PCT/US15/46373 filed Aug. 21, 2015 U.S. provisional application No. 62/039,914 dated Aug. 21, 2014 the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Hypertension 
         [0003]    Tight blood pressure control is critical during certain types of surgery and post-operatively in the ICU. Hypertensive emergencies in of themselves can cause severe bodily injury. In the eye severe hypertension can cause retinopathy and papilledema, in the brain hypertensive encephalopathy, cerebral infarction, and subarachnoid or intracranial hemorrhage, the cardiovascular system can experience myocardial ischemia and infarction, acute left ventricular dysfunction, acute pulmonary edema, and aortic dissection and the kidney can experience renal insufficiency and acute renal failure. 
         [0004]    Perioperative Hypertension 
         [0005]    Hypertension in the perioperative period can have similar consequences as hypertensive emergencies. In addition perioperative hypertension can result in increased bleeding at the operative site. With respect to certain surgical procedures such as cardiac, vascular, or neurosurgical operations, hypertensive bleeding can be catastrophic. 
         [0006]    Hypotension 
         [0007]    Hypotension can result in decreased blood flow to end organs causing ischemia and organ system failure such as ischemic stroke, myocardial infarction, acute renal failure, hepatic necrosis and if hypotension is prolonged it results in death. 
         [0008]    Perioperative Hypotension 
         [0009]    Clinical studies have shown that tight blood pressure control in the operating room during cardiac surgery and perioperatively can reduce the risk of renal dysfunction, which has a major impact on quality of life. Many investigators have also found that intraoperative hypo or hypertensive events significantly influence the risk of perioperative cardiac morbidity. In the patient with coronary disease undergoing major surgery such as: emergency surgery, vascular surgery, prolonged thoracic or upper abdominal surgery or cardiac surgery, intraoperative hypotension is a major hemodynamic risk factor associated with significantly increased myocardial infarction rates. In patients with a previous myocardial infarction intraoperative hypotension has been found to result in a five-fold increase in the reinfarction rate. Although hypotension reduces myocardial demand and wall tension it also decreases coronary blood flow which can result in myocardial infarction. Perioperative hypotension can also result in ischemic stroke, renal failure and hepatic necrosis. 
         [0010]    Demand for Tight Blood Pressure Control 
         [0011]    There is a demand for tight blood pressure control intra and postoperatively for certain surgical procedures as well as during the critical care of other medical situations where control of pressure within a certain range is paramount. Often surgeons give ICU nurses a blood pressure range that they would like their patients to remain in. This blood pressure range is often a compromise between the desire to control post-operative bleeding (as low a blood pressure as possible) and the maintenance of adequate end organ perfusion (a higher blood pressure usually around the patients baseline pressure). The ability to control pressure in a tight range is a difficult one at best. There are so many dynamic factors that come together to determine a patient&#39;s blood pressure at any one moment in time and those factors are constantly changing. It is not uncommon to witness a severe undershoot and/or an overshoot in the same patient with regards to requested blood pressure parameters. 
         [0012]    Intravenous Drugs Used to Control Blood Pressure 
         [0013]    There are two basic types of intravenous drugs used to control blood pressure. Vasodilators are drugs that dilate vessels and decrease blood pressure and Vasoconstrictors that constrict blood vessels causing blood pressure to rise. Often it is not so simple and compounding factors such as the patient&#39;s current blood volume, sedation level, cardiac contractility and other vasoactive drugs can make pressure control difficult with these drugs. Each patient reacts differently to these drugs compounding the confusion so that no single dose is sufficient for any patient and each patient&#39;s needs are constantly changing; making the titration of these intravenous vasoactive drugs difficult for anesthesiologists and ICU personnel. 
         [0014]    Relevant Art 
         [0015]    Different inventions have been patented that try to address this situation. European Patent number EP0408483 B1 prescribes the use of a single vasodilator with varied inputs such as the use of a BP cuff or invasive arterial pressure. This device however is broad in its description and involves the use of only a single drug to control only hypertension. U.S. Pat. No. 8,608,683—Device for infusion of at least two medicaments is a complex system that incorporates so many parameters as to make the system unusable, it however does involve the use and control of multiple drug infusions and inputs. Neither of these patented inventions are in widespread use due to their general non-specific nature and usefulness and both lack a visual or textual physiological balance indicator. These inventions also do not allow for the ability to automatically control blood pressure to a user selected value or a tight range. A physiological balance mechanism or indicator allows the user to determine at a glance how well balanced the system is according to a user set target pressure and range. Neither of the prior inventions incorporates a means of determining the physiologic balance. Also neither device accounts for variable sensitivities to certain vasoactive medications within the time course of treatment. 
         [0016]    These publications and all other referenced patents are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is an incorporated reference here, is inconsistent or contrary to the definition of that term provided herein the definition of the term provided herein applies and the definition of that term in the reference does not apply. 
       SUMMARY 
       [0017]    An automated pressure control device that is useful will allow the user to determine a target pressure and range as well as incorporate either a textual or visual physiologic balance indicator that will assist the device and user in maintaining its preset target pressure within its user defined range. The physiologic balance indicator interfaces with the user by providing advisories, cautions and warnings on how well the device is able to maintain its set target and range. User input by way of outside interventions such as increased fluids, decreased anesthetics etc. will almost always be required at some point to maintain a preset target pressure and range. By combining the technologies behind auto-pilots in aircraft with interactive ‘smart’ intravenous pumps, arterial wave form monitoring, and a combination of vasodilator and vasoconstrictive intravenous drugs, a useful device will be able to automatically control arterial systolic blood pressure or mean arterial blood pressure to a user defined target value and continue to maintain that pressure within a user set range. The device can automatically control the arterial systolic pressure and maintain it within a user set range far more accurately and with infinitely more vigilance than any human can do so by altering the drip rate of vasoactive drugs through a set of infusion pumps. Vasoactive drugs are rapidly metabolized and they require extreme vigilance to maintain a pressure within a predetermined range. Notwithstanding this but depending on the circumstances a vasodilator may be needed followed rapidly by a vasoconstrictor within minutes of each other as patient&#39;s pressures can vary rapidly and without warning. 
         [0018]    Physiological systems are very dynamic and not well characterized. Anesthesiologists witness different sensitivity of patients to the same medication and changes in the same patient&#39;s sensitivity to any drug in time (for example, tachyphylaxis, etc.). It is desirable to use a controller or automated device that can rapidly adapt to the changing cardiovascular parameters of any particular patient or situation. The controller in the present invention rapidly updates its parameters based on the latency and response to current doses as well s test dosages in relation to the cardiovascular system and both vasoactive substances. 
         [0019]    Still further advantages will become apparent from a study of the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a drawing of the invention with vasoactive drug filled bags attached to a patient and close-up view of a connector to central venous infusion line. 
           [0021]      FIG. 2  shows a profile of a dual lumen catheter. 
           [0022]      FIG. 3  is an overall view of a central venous catheter setup. 
           [0023]      FIG. 4  shows the device interface of the device. 
           [0024]      FIG. 5  is a flow chart illustrating operational steps of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  is an overview of the device  10  showing vasodilator solution bag  12 , carrier solution bag  14 , vasoconstrictor solution bag  16  each with its own access tubing entering the intravenous line housing  18  on the right hand side of the device  10  that houses three separate IV pump channels. Each line will have a means for a safety lock device or alternatively a single standard lock for the coalesced lines exiting the bottom on the IV infusion compartment. Out of the bottom of the IV infusion compartment a single line emerges that is actually three tubing channels in one line. This multi lumen infusion line  30  then will go to the connector port  32  that will connect to a central venous access line  34  for the patient. Entering the backside of the device is a pressure transducer cable  21  that will interface with the existing transducer to bring the arterial line  20  pressure signal into the device  10 . 
         [0026]      FIG. 1  shows an overview of a standard invasive radial arterial monitoring setup, with A-line  20 , transducer  22 , external pressure monitor  26 , and pressure bag  24 . A ‘Y’ transducer cable  23  will interface the transducer signal to both the external monitor  26  and the device  10  via cable  21 . Alternatively a ‘Y’ arterial line will connect to a separate transducer that will interface with the device  10 . The device  10  further comprises a computer with microprocessor and ram that has a full color display to interface with a physician or care giver. 
         [0027]      FIG. 2  shows a close up view of the multi lumen infusion line  30  and a cross-section view of a multi lumen line  28 , showing that there are three ns inside of the multi lumen infusion line  30 . The multi lumen infusion line  30  leads to the connector port  32  which has a flow through design. One embodiment of this connector port  32  will have an anti-reflux valve at the top of the connector port  32  to prevent vasoactive solution moving up a piggybacked IV line if the connector port  32  has a flow through design. Another embodiment of this connector part  32  is just a sealed top and open infuser bottom. The connector port  32  is connected to the central venous line  34  that is very close to the patient and eliminates the need for large volumes of solution to be infused in to the patient or to clear lines or the need to flush the central venous line  34  between solution changes. 
         [0028]      FIG. 3  shows a standard central line  34  infusion setup on a patient. The preferred method of use is through a central line  34 , but the device  10  may be used with a peripheral access line, however the response time of the patient will be slower due to blood flow considerations. The connector port  32  will connect to the central line  34  as shown by arrow  36 . 
         [0029]      FIG. 4  shows one embodiment of the device  10  touch screen device interface  54  with user selected target and range window  40  in the upper right corner, mode annunciation  38  in the upper left, the physiologic balance indicator in the upper mid portion of the device face with the dilator balance  46  on the left, and the pressor balance  42  on the right. The pressor bolus button  44  is touched by the physician to dose the patient with a vasoconstrictor, the dilator bolus button is used by the physician to deliver a dose of vasodilator. In other words, this is a manual override and can be used while the device is in manual or auto mode. If things are happening quickly for example, say the surgeon just lifted the heart up and the blood pressure plummeted and the anesthesiologist needed a quick bolus the user could push one of the buttons and the device would deliver a quick bolus that the user has preselected a dosage for. In the lower mid portion of the device face is an arterial pressure tracing and arterial pressure reading  48 . The Warning, Caution, Advisory and Alerts section  50  is just below the arterial pressure tracing and arterial pressure reading  48  area. Alerts section  50  signals warnings in red, cautions in yellow and advisories in grey and presents them in the alerts section  50 . At the bottom of the touch screen interface is the menu area  52 . Each menu button brings up a separate menu to address that specific menu item. For instance the mode button initiates a separate menu that has the user select a mode for the device to operate in, manual vs. auto mode and any specific menu items that are needed to operate the device in that mode. Along the bottom of the device interface  54  are touch screen buttons: “Menu” brings up a sub menu screen that allows the user to select the dosages for bolus buttons, and another sub menu to determine whether or not a baseline infusion of either dilator or constrictor is desired in auto mode and what that infusion rate would be. “Mode” button brings up a submenu that tells the user the current mode the device is in as well as a submenu that allows for various infusions and rates in the Manual mode. “Target” brings up a submenu that asks for the range input and target pressure input. “Dilator” brings up a submenu that asks for the name of the specific vasodilator used and its concentration. It also gives a current readout of the total dilator used thus far in the case and the ability to reset the value. “Pressor” brings up a submenu that asks for the pressor drug name and the concentration in the vasoconstrictor solution bag  16 , as well as a readout of the current total dosage given and the ability to reset the value. “Start” brings up a submenu that asks if the user wishes to start the infusion in either Auto or Manual mode. “Stop” brings up a submenu that asks the user if they wish to confirm stopping all infusions. 
       REFERENCE NUMERALS 
       [0000]    
       
         
           
               12  vasodilator solution bag 
               14  carrier solution bag 
               16  vasoconstrictor solution bag 
               18  intravenous line housing 
               20  Arterial Line 
               21  Transducer Cable 
               22  Arterial Pressure Transducer 
               23  Transducer Cable ‘Y’ Split 
               24  Arterial Line Pressure Bag 
               26  External Monitor 
               28  Cross Section of multi lumen infusion line 
               30  multi lumen infusion line 
               32  connector port 
               34  an example of a central venous line 
               36  connector port  32  connecting to central venous line  34   
               38  mode annunciation window 
               40  target and range window 
               42  pressor balance 
               44  Bolus Activation Button 
               46  dilator balance 
               48  arterial pressure tracing and arterial pressure reading 
               50  alert section 
               52  menu area 
               54  Device Interface 
           
         
       
     
       OPERATION 
       [0054]    In operation the device will be powered on and specialized vasoactive line tubing will be spiked into the vasoconstrictor solution bag  16  and vasodilator solution bag  12  as well as the carrier solution  14 . Each solution line has a channel as in standard intravenous pumps. The vasoconstrictor line may be coded and colored red, the vasodilator line may be coded and colored blue to minimize errors. The device undergoes a standard intravenous line check. Vasoactive solutions will be identified and input by the user including their respective concentrations. The device is capable of two modes, manual and auto. In manual mode the device will have the means to infuse either the dilator or constrictor or both at user specified rates. In auto mode the device will require an incoming arterial transducer line  21  with means to enable the device to read the arterial pressure signal, alternatively this will come from a ‘Y’ arterial line and separate transducer and line that will interface with the device. From this transducer line  21  the arterial waveform and derived systolic pressure will be displayed on the arterial pressure tracing and arterial pressure reading  48 . If the waveform is too damped or unusable the device will go into standby mode until the tracing is corrected, and activate the alert window giving an alert section  50 . In auto mode the user inputs a target systolic pressure with a range above and below the target value  40 . The device will give a small test dose of each vasoactive solution in order to determine appropriate controller parameters. For example in the auto mode, an algorithm, PID controller, or similar controller analyzes the patient response to the drug and calculates a rate for drug infusion based on the user inputs for drug concentration. When the device is ready the user activates the auto mode and the device will maintain the user selected target pressure. The degree to which the device is ‘fighting’ to maintain target pressure will be displayed on the balance indicator  42 ,  46  along with alert section  50 . Alerts are in the form of recommendations to the user in order to assist the device in maintaining the target value. 
         [0055]    In an alternative embodiment the device operates without the use of invasive blood pressure readings via a blood pressure cuff or one of the new continuous noninvasive blood pressure measuring devices. 
         [0056]    The ability of the device to use any available vasopressors or vasodilators, such as nitroglycerin, nitroprusside, nicardipine, epinephrine, norepinephrine, phenylephrine or newly developed medications etc. are alternative embodiments. 
         [0057]    In an alternative embodiment the device calculates adding an inotrope to the vasopressor bag to provide inotropic support as well as vasoconstriction. 
         [0058]    In all of the embodiments the blood pressure measurements can be recorded locally on the device with removable memory or accessible via conventional USB or other connectors. Additionally, each embodiment can utilize WiFi, BlueTooth®, or other wireless communication to send patient data to a remote server for recording or remote analysis. 
         [0059]    The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. Based on the above discussion and illustrations, those skilled in the art will readily recognize that various modifications and changes may be made to the present invention without strictly following the exemplary embodiments and applications illustrated and described herein. Such modifications and changes do not depart from the true spirit and scope of the present invention.