Apparatus for measuring central venous oxygen saturation during human cardiopulmonary resuscitation and clinical shock, and for treating the patient

Abstract: A fiber optic catheter for continuous measurement of central venous oxygen saturation (Scv02) during human cardiopulmonary arrest and shock. When applied in cardiopulmonary arrest (cardiac arrest), the catheter provides therapeutic and prognostic guidelines in the management of a patient in this condition. The catheter also serves as a conduit for fluid and drug infusion and as a sampling port for venous blood. The catheter comprises a body having a first port that exits through a connector body to the computer interface that provides the sending signal and receiving signal which generates central venous oxygen saturation readings. A fiberoptic bundle of afferent and efferent light-conducting fibers transverses the first port to provide signal generation and interpretation of oxygen measured in the blood. A second port is a lumen that traverses and exits at the distal port to allow for pressure measurement and sampling of the venous blood. A third proximal port provides an opening of a lumen that transverses and exits the catheter via a side port spaced from the skin insertion site.

Description: This invention relates to a device for assisting in treating a patient in cardiac arrest, with continuously monitoring the hemodynamic status of a patient in cardiac arrest and undergoing cardiopulmatory resuscition (CDR). A venous catheter is described in WO-A-88/10128. Whereas this catheter can be introduced to vessels near the heart, it is only used for vascular access and blood pressure measurement. There are no means for measuring the central venous oxygen saturation during cardiac arrest and shock. An apparatus for determining oxygen saturation levels is known from US-A-4,623,248. The site to measure in the human body is not given. Measurement of venous blood oxygen is known from EP-A-266,928. A catheter having optical fiber means is used to monitor pulmonary-artery pressure, i. e. has to be introduced into the heart and lungs through an artery. This can only be done, if there is sufficient blood pressure and blood flow in order for the catheter to be placed in the appropriate position. This is not possible when a patient is in cardiac arrest or severe shock. Cardiac arrest is one of the most dynamic pathophysiologic events in clinical medicine. An immediate cascade of pathologic processes is triggered secondary to the abrupt cessation of oxygen delivery. Since oxygen is not stored in sufficient quantities in the body, interruption of adequate oxygen transport to the cells for brief periods of time can result in death. Advanced cardiac life support (ACLS) attempts to provide oxygen delivery and thereby attenuate this cascade. Rapid and substantial improvement in oxygen delivery is required to decrease the morbidity and mortality of ischemic organ injury. Current monitoring techniques used in ACLS include continuous electrocardiographic monitoring and physical examination e.g. palpation of the carotid or femoral pulse. Both of these techniques provide little information regarding hemodynamic status and oxygen delivery to the brain or body. Clinical monitoring techniques used as prognostic and therapeutic indicators during ACLS include the coronary perfusion pressure (CPP) or aortic to right atrial relaxation phase pressure gradients, and end-tidal carbon dioxide concentration (ETC02). The importance of CPP as a prognostic indicator of return of spontaneous circulation (ROSC) during animal and human CPR is well established. CPP is the "gold" standard for measuring hemodynamic response to therapy during cardio pulmonary resuscitation (CPR). Calculation of CPP requires placement of both an aortic artery and central venous catheter which may limit its applicability. ETC02 has been studies in animals and humans and has been proposed as a prognostic and therapeutic guide during CPR. Although ETC02 has the advantage of being non-invasive, it is influenced by multiple variables (i.e. aspiration, pre-existing pulmonary disease) that may limit its reflection of blood flow and CPP in the setting of cardiac arrest. A study made by E.P. Rivers et al. was presented at the Annual Meeting of the Society for Academic Emergency Medicine, held in Washington (USA) on May 12-15, 1995. The study explores the utility of Scv O 2 as indicator of ROSC. It is an object of this invention to provide a device which makes possible continuous central venous oxygen measurement during cardiac arrest and which enables a treating clinician to tailor therapy and formulate a prognosis in the treatment of a patient in shock and cardiac arrest. Using the concentration of oxygen in central venous blood, decisions can be made regarding hemodynamic status in response to therapy and predict outcome. The invention is defined in claim 1. Scv02 monitoring in accordance with the present invention requires only central venous cannulation while Ao-Ra requires venous and arterial cannulation. Scv02 monitoring is not affected by the same extrinsic variables that affect ETC02. Mixed venous blood reflects tissue oxygen (02) delivery during cardiac arrest and circulatory failure. Selective venous hypoxemia or low oxygen content when compared to arterial blood are characteristic during cardiac arrest. Intermittent mixed venous oxygen saturation measurement during ACLS predicts outcome in cardiac arrest patients and hemodynamically unstable trauma patients. In studies made in accordance with the invention, patients successfully resuscitated had higher central venous oxygen saturations than non-resuscitated patients. As far as the present invention is aware, this is the first measurement of this parameter continuously in cardiac arrest patients with fiberoptic technology. Ideally, mixed venous blood should be drawn from a pulmonary artery catheter. However, placement of such a catheter is unlikely during cardiac arrest. A number of studies have supported the substitution of central venous (right arterial or superior vena cava) blood for mixed venous blood (pulmonary arterial) during spontaneous circulation, circulatory failure and closed chest ACLS. There is reported no significant difference between pulmonary artery, central and femoral venous blood gases during closed chest ACLS in animals. The device in accordance with the invention utilize the concept of Scv02. The information provided by such a device is a guide to the care of patients in cardiac arrest. It is believed that this is the first utilization of a catheter of this type in this clinical situation. The present invention includes a device comprising a catheter specific for utilization in cardiopulmonary resuscitation. In accordance with the invention, a fiberoptic catheter is provided for continuous measurement of central venous oxygen saturation (Scv02) during human cardiopulmonary arrest and shock. When applied in cardiopulmonary arrest, the catheter provides therapeutic and prognostic guidelines in the management of a patient in this condition. The catheter also serves as a conduit for fluid infusion, drug administration, and as a sampling port for venous blood. The catheter comprises a body having a first port that exits through a connector body to the computer interface and provides the sending signal and receiving signal that generates central venous oxygen saturation readings. A fiberoptic bundle of afferent and efferent light-conducting fiber transverses the first port to provide signal generation and interpretation of oxygen measured in the blood. A second port is a lumen that traverses and exits at the distal port to allow for pressure measurement and sampling of the venous blood. A third proximal port provides an opening of a lumen that transverses and exits the catheter via a side port 10 cm from the skin insertion site. Description of the Drawings FIG. 1 is a schematic of a fiber optic catheter embodying the invention and adapted to be used in the method. FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1. FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1. FIG. 4 is an end view from the left as viewed in FIG. 1. Description In accordance with the invention, the apparatus for measuring central venous oxygen saturation comprises a fiber optic catheter 10 for continuous measurement of central venous oxygen saturation (Scv02) during human cardiopulmonary arrest and shock. When applied in cardiopulmonary arrest, the catheter provides therapeutic and prognostic guidelines in the management of a patient in this condition. The catheter also serves as a conduit for fluid and drug infusion and as a sampling port for venous blood. The catheter comprises a body B having a first port 11 that exits through the connector body B to the computer interface and provides the sending signal and receiving signal that generates central venous oxygen saturation readings. A fiberoptic bundle of afferent and efferent light-conducting fibers transverses the first port 11 (diameter .6 mm) to provide signal generation and interpretation of oxygen measured in the blood. A second port 12 is a lumen that traverses and exits at the distal port P to allow for pressure measurement and sampling of the venous blood. A third proximal 13 port provides an opening of the lumen from proximal infusion port I that transverses and exits the catheter via a side port 14 preferably less than 10 centimeters from the skin insertion site. These ports allow for pressure measurement, fluid or drug administration. The placement of port 14 is important to avoid signal artifact (distortion) when infusing large volumes of fluid or drugs. Referring to FIGS. 1 and 2, the catheter 10 includes a body 20 including a first catheter portion 21 and a second frustoconical body portion 22. The first portion 21 is adapted to be inserted into the blood vessel and preferably has a length of at least 19 cm. The first portion 21 is capable of flexing during insertion but has sufficient rigidity that it will not be flexed during turbulent blood flow. The body 20 further includes a second portion 22 that is sufficiently rigid to maintain the lumens relatively fixed to one another and to withstand the external compression forces of an introducer of conventional construction. The lumens 11, 12, 13 extend externally from body 20 to the respective connector body B, distal port P and proximal infusion port I. Referring to FIGS. 1 and 2, a preferred form of the catheter 10 comprises a body of urethane having three lumens extending therethrough. The polyurethane catheter may have a length of 19 centimeters long and a diameter of 2.3 mm (7 French) for optimal placement into the (patient) venous system. The 7 French diameter is needed for the appropriate compliance. It has a slight curvature to avoid contact with the vessel walls as it enters and resides in the venous system. It can be placed through an introducer, preferably 2.5 mm (7.5 French), to avoid damage to the optic fibers that exit from the distal port. The proximal or first portion 21 aspect of the catheter as it enters the skin is reinforced and tapered for 3 centimeters to avoid damage of the fiberoptic bundles and compression of the infusion and sampling ports when a tight fitting introducer is used. The proximal aspect of the catheter 10 has a first port 11 that exits through a connector body to the computer interface and provides the sending signal and receiving signal that generates central venous oxygen saturation readings. A fiberoptic bundle of afferent and efferent light-conducting fiver transverses the first port 11 (diameter .6 mm) to provide signal generation and interpretation of oxygen measured in the blood. A second port 12 is a lumen that traverses all 19 centimeters (.6 mm) and exits at the distal port to allow for pressure measurement and sampling of the venous blood. A third proximal port 13 (.9 mm) provides an opening of the lumen that transverses and exits the catheter via a side port 10 centimeters from the skin insertion site. In a study approved by the Henry Ford Hospital Institutional Review Board for Human Research, one hundred consecutive patients presented to the emergency department (ED) in non-traumatic, normothermic cardiopulmonary arrest were studied. Cardiopulmonary arrest was defined as the absence of a palpable pulse and respirations and was later verified by the absence of spontaneous aortic pulsations on the pressure tracing. Patients received only asic Cardiac Life Support (BCLS) by emergency medical service (EMS) personnel prior to admittance to the ED. Upon arrival, patients were clinically managed by emergency medicine physicians using Advanced Cardiac Life Support (ACLS) guidelines. The epinephrine dose (.01 to .2 mg/kg) was used at the clinician's discretion. CPR was performed by a pneumatic compression device (Thumper, Michigan Instruments, Grand Rapids, MI) at a compression rate of 80/minute and an excursion of 38.1-50.8mm (1½-2inches). Ventilation of 80% oxygen was provided between compressions at a 5:1 ratio. Catheter placement, data recording and blood sampling were performed by on-call research personnel, who had no active involvement in the clinical management of the patient. All catheters were simultaneously placed. A 2.5 mm (7.5 French introducer was percutaneously placed into the central venous system via the subclabian vein. "French" is a customary unit of measure for catheter and needle diameter, one French being equal to a third of a millimeter. The side port 14 was used for drug and fluid administration. The infrared, fiberoptic catheter 10 was advanced through the central port of the introducer into the central venous system. The distal lumen 12 on the fiberoptic catheter was used for central venous gas sampling and pressure measurement. For arterial pressure monitoring, a 60 cm 2.6 mm (5.8 French) catheter was placed in the aortic arch, either percutaneously or by cut down technique, via the femoral artery. The catheters were connected to precalibrated pressure transducers through a heparinized saline flush system. The resulting signals were amplified and pressure tracings were recorded throughout CPR and during the initial post-resuscitation period. Correct catheter positions were confirmed by supine chest radiograph at the end of ACLS. Hemoglobin, hematocrit, simultaneous arterial and venous blood gases were obtained every 10 minutes throughout the resuscitation. The fiberoptic catheter 10 was precalibrated in vitro before insertion. During the cardiac arrest, the initially measured 02 saturation of the venous blood gas samples was used for an in vivo calibration of the Scv02 monitor. Initial (the first values obtained in the arrest), mean (average of all values obtained during arrest) and maximal (higher value obtained during the cardiac arrest before return of spontaneous circulation (ROSC) were recorded. ROSC was defined as the development of a spontaneous pulse wave form on the arterial tracing associated with a systolic blood pressure greater than 60 mm Hg for more than 5 minutes. Cardiac arrest was defined as the absence of a pulsatile arterial tracing or a systolic blood pressure of less than 60 mm Hg. Sixty-eight episodes of ROSC or blood pressure were observed. Patients with ROSC had higher initial, mean, and maximal Scv02 compared to those without ROSC (p=.23,.0001, and .0001, respectively). The positive predictive value for ROSC with a maximum Scv02 of greater than 60% and 72% was .93 and 1.0, respectively. The negative predictive value for ROSC with a maximum Scv02 of less than 30% and 40% was 1.0 and .93 respectively. Only one of 68 episodes of ROSC was attained with a maximum Scv02 of less than 40%. High dose epinephrine (.2 mg/kg) depresses Scv02 temporarily, and this effect decreases with the duration of arrest. continuous Scv02 monitoring can serve as an adjunct in monitoring therapeutic response and as an prognosticator of ROSC during cardiopulmonary resuscitation (CPR). Using the catheter of this invention and data obtained, one can determine the effectiveness of therapy in providing adequate circulation or blood flow during CPR. This is the amount of oxygen that is delivered throughout the body. When the Scv02 is above 60%, the chances of having a blood pressure or beating heart is 93%. When the Scv02 is above 72%, there is a 100% chance of having a blood pressure. If the patient never obtains an Scv02 of above 40%, there is no chance of survival and should not be resuscitated indefinitely beyond 30 minutes with a value below this number. The catheter thus provides the following advantages: 1. A fiber optic central venous catheter and methods specifically for use in cardiopulmonary resuscitation and shock. 2. A fiber optic catheter specific for use in the central venous position during cardiac arrest and shock states in which the patient is resuscitated from low or no blood pressures. In this condition the patient is in delivery dependent oxygen consumption state which allows for the use of Scv02 as a diagnostic and therapeutic modality. It has greater prognostic value than measurement of arterial blood pressure. Thus, the catheter comprises three lumens, a body, said body having a first portion that extends into the blood vessel for a length of at least 19 cm, said first portion being capable of flexing during insertion but will remain rigid and not flex during turbulent blood flow, a second portion being rigid to maintain the lumens relatively fixed to one another and to withstand the external compression forces of an introducer, said lumens extending externally to a connector body to a computer interface, a distal infusion port and a proximal infusion port, respectively, said lumens for said proximal infusion port extending radially to a side surface of the first portion of the body. The length of the catheter portion 21 is preferably less than 20 cm from the skin to the end of the catheter. The lumen side port 14 must be at least 9 cm from the end of the catheter portion 21 and must be flexible to avoid contact with the blood vessel walls and must be sufficiently rigid that it will not flex due to variations in blood pressure. The method of managing a patient in cardiac arrest who is undergoing CPR comprises placing first portion of a catheter in the central venous system, connecting one lumen to computer to measure central venous oxygen saturation, utilizing said second and third lumens for volume and fluid infusion, pressure measurement and sampling of venous blood in accordance with ACLS guidelines. (a) If Scv02 is greater than 60%, interrupting the CPR and obtaining the blood pressure such that advanced cardiac life support can be tailored to treating a spontaneously beating heart, (b) if the Scv02 is above 73%, interrupting CPR and treating the patient as one with a spontaneously beating heart, (c) if the patient does not attain an Scv02 of above 40% during 30 minutes of recording and treatment for cardiac arrest, continued attempts at resuscitation are not warranted.

Claims: A device for continuously monitoring the hemodynamic status of a patient in cardiac arrest and undergoing cardiopulmatory resuscitation (CPR), and treating the patient comprising a venous catheter, a computer including a ScvO2 monitor, means for pressure measurement and sampling of venous blood, and infusion means, said venous catheter comprising a tubular body (20) including a first distal flexible portion (21) having a cross-sectional size adapted for insertion into a central venous blood vessel, and a second proximal rigid portion (22); the tubular body (20) having three lumens (11, 12, 13) in it which extend through the second portion (22) and at least partially through the first portion (21); tubing means including three lumens (11, 12, 13) connected to the lumens (11, 12, 13) of the tubular body (20) and including a connector body (B) attached to said computer including said ScvO2 monitor, a pressure measuring port (P) connected to said means for pressure measurement and sampling of venous blood, and an infusion port (I) connected to said infusion means, wherein said first portion (21) of the catheter (10) has a length that is less than 20 cm and has a flexing capability allowing the first portion (21) to flex during insertion of the catheter, but remaining sufficiently rigid and not flexing during turbulent blood flow, and wherein said first lumen (11) within the tubing means and the tubular body is traversed by a fiber optic bundle of afferent and efferent light-conducting fibers for sending signals and receiving signals for generating central venous oxygen saturation readings so that the catheter (10) can be used in treating a patient during and after cardiac arrest who is undergoing cardio pulmonary resuscitation (CPR). The device of claim 1 wherein the length of said first portion (21) is 19 cm and its diameter is 2.3 mm. The device set forth in claims 1 or 2 wherein said second portion (22) comprises a frustoconical body which is rigid for maintaining the lumens (11, 12, 13) relatively fixed to one another and capable of withstanding external compression forces created by an introducer through which the catheter (10) may be placed. The device of claim 3 wherein said first portion (21) is reinforced and tapered for 3 cm at the transition to said second portion (22). The device set forth in any of claims 1 to 4 wherein said first lumen (11) extends from a free end face of said tubular body (20) to said connector body (B) for attachement to said computer including said ScvO2 monitor. The device set forth in one of claims 1 to 5 wherein said second lumen (12) extends from the free end face of the tubular body (20) to said pressure port (P) . The device set forth in one of claims 1 to 6 wherein said third lumen (13) extends from said infusion port (I) to an infusion outlet opening (14) for fluid or drug administration. The device set forth in claim 7 wherein said infusion outlet opening (14) is less than 10 cm from the skin insertion site of said tubular body (20) . The device set forth in one of claims 1 to 8 wherein said third lumen (13) has an inner diameter of 0.9 mm. The device set forth in one of claims 1 to 9 wherein said first and second lumens (11, 12) each have an inner diameter of 0.6 mm. The device of any of claims 1 to 10 wherein said computer including said ScvO2 monitor is adapted (a) for indicating that the ScvO2 is greater than 60% during CPR, and give the advice to interrupt CPR and obtain the blood pressure such that advanced cardiac life support (ACLS) can be tailored to a beating heart, (b) for indicating that the ScvO2 is above 73%, and give the advice to immediately interrupt CPR and treat the patient as one with the beating heart, (c) for indicating that the patient does not attain an ScvO2 of above 40% during 30 minutes of recording and treatment for cardiac arrest, and warning that continued attempts at resuscitation are not warranted, and (d) for indicating that the ScvO2 is less than 40% after a heart beat has been established and warning that precautions must be taken immediately because the patient will have another cardiac arrest within minutes.

Inventors: RIVERS EMANUEL P M D, RIVERS, EMANUEL P., M.D.
Applicants: FORD HENRY HOSPITAL, HENRY FORD HOSPITAL
Application year: 1993
Main classification: A61B5
IPC codes: A61B5