Abstract: A method is described for assessing perfusion failure of a patient by measurement pCO.sub.2 (partial pressure of carbon dioxide) in the digestive system of the patient. The method includes introducing a catheter (10, FIG. 1) through the nasal passage until a sensor (12) on the catheter lies in the esophagus, and taking measurements of CO.sub.2 in the esophagus. The measurements can be taken at the wall of the esophagus without inflating a balloon, by instead allowing the walls of the esophagus to contract about the catheter and the sensor thereof. The measurement involves minimal invasion while avoiding false readings such as those arising from CO.sub.2 produced in the stomach during digestion.

Abstract: A method and apparatus are described for resuscitating a person who has suffered cardiac arrest. The method includes threading a balloon through the aorta until it lies along the ascending aorta, and then inflating the balloon (40, FIG. 1) to block the ascending aorta to thereby increase blood flow into the coronary arteries (30, 32). A tube (42) extends through the balloon, and blood-compatible fluid which is preferable oxygen rich, is injected past the balloon to provide additional oxygen-carrying fluid to flow through the coronary arteries when the balloon is inflated. The balloon is repeatedly deflated and inflated, so after a period of perhaps 30 seconds during which blood flows only to the coronary arteries, the balloon is deflated to allow some blood flow to the brain. During the entire procedure, pressure is repeatedly applied to the chest and therefore to the heart to sustain blood circulation.

Abstract: Apparatus for facilitating the performance of medical procedures involving the vascular system of a patient, especially in a critical care environment, such as withdrawal of blood for analysis and infusion of medication. In the taking of a blood sample, blood flows through an arterial catheter connected to an artery of the patient, past a sample station, and then through a venous catheter that brings the blood back to the patient, the various mechanisms being connected by transparent plastic tubes. After a sample is taken, the tubes are flushed through the sample station, arterial catheter, and the venous catheter. Calibration of all pressure transducers requires application of high and low pressures to them, the high pressure being obtained by applying a high pressure (e.g. 200 mm Hg) to a bottle of saline solution which is also utilized to flush the tubes and which is connected to all of the transducers.

Abstract: A monitor is described for use with an intravenous injection system of the type that includes an accumulator (18) located between the pump (14) and the needle (28) that connects to the patient's vein. The monitor generates an alarm when there is infiltration (no resistance to outflow, as when the needle withdraws from a vein) or occlusion (the needle is blocked). The monitor includes a pressure sensor (32) coupled to the accumulator, and a circuit (34) which responds to the rate of change of the pressure to operate an alarm when the rate of change exceeds a predetermined amount such as 5 mm Hg, but only when it exceeds that value over a particular time period such as 10 seconds or one minute.

Abstract: High frequency medical breathing apparatus is provided, which delivers efficiently controlled high frequency air pulses to a catheter, and which is of relatively low cost and is energized by pressured air that is commonly available in a hospital environment. The apparatus includes a large flexible bag with entrance and exit openings, walls forming a sealed chamber around the bag, and a source that applies pressure pulses to the chamber to partially compress the bag at each pulse so as to deliver air through the exit end of the bag and a check valve, and into a catheter that leads to a patient's lungs.

Abstract: An apparatus is provided for injecting fluid into a patient over an extended period of time, such as in intravenous feeding of a patient. The apparatus enables close control of injection quantity and rate while assuring an even flow into the patient. The apparatus utilizes relatively simple disposable parts. The apparatus includes an air-operated peristaltic pump which pumps a controlled amount of fluid in each cycle of operation, and a pressure moderator which receives the liquid pulses and supplies an even flow to the patient. The moderator includes a closed chamber, and a resilient tube connected to the pump and having slits that permit the escape of pumped liquid into the chamber. The peristaltic pump includes a flexible but nonresilient tube connected to the container, the nonelasticity assuring that the tube does not expand beyond a predetermined dimension when a vacuum is applied to it.

Abstract: A method and apparatus for assessing the condition of a patient in circulatory shock by measuring the peripheral or skin temperature of the patient, as by measuring the difference between the patient's toe temperature and ambient temperature, which is more accurate than heretofore. The gradient of the toe-minus-ambient temperature difference is calculated, and an indication of poor condition is given if the toe-minus-ambient temperature difference does not rise by at least a predetermined amount such as 3.degree. C. within a predetermined period such as ten hours. Instead of taking only the difference between the temperature at one toe and ambient, the temperatures at both large toes of the patient are taken and the difference between the higher of the two toe temperatures minus ambient is utilized in the calculations that provide an indication of patient condition.

Abstract: Apparatus for facilitating the performance of medical procedures involving the vascular system of a patient, especially in a critical care environment, such as withdrawal of blood for analysis and infusion of medication. In the taking of a blood sample, blood flows through an arterial catheter connected to an artery of the patient, past a sample station, and then through a venous catheter that brings the blood back to the patient, the various mechanisms being connected by transparent plastic tubes. After a sample is taken, the tubes are flushed through the sample station, arterial catheter, and the venous catheter. Calibration of all pressure transducers requires application of high and low pressures to them, the high pressure being obtained by applying a high pressure (e.g. 200 mm Hg) to a bottle of saline solution which is also utilized to flush the tubes and which is connected to all of the transducers.