Humidifier

• US 5,163,423 A
• Filed: 11/29/1991
• Issued: 11/17/1992
• Est. Priority Date: 11/30/1990
• Status: Expired due to Fees

• Current Assignee: Origin Medical Instrument Co., Ltd.
• Original Assignee: Origin Medical Instrument Co., Ltd.
• Inventors: Suzuki, Shiro
• Primary Examiner(s): Millin, Vincent
• Assistant Examiner(s): Passaniti, Sebastiano
• Application Number:
  US07/800,099
• Time in Patent Office: 354 Days
• Field of Search: 128/203.26, 128/203.27, 128/204.17, 128/203.16, 128/203.17, 128/207.14, 128/205.23, 236/44 A
• US Class Current: 128/203.26
• CPC Class Codes: A61M 16/08 Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/1085 after being humidified or mixed with a beneficial agent
• CPC Class Codes: A61M 16/109 the humidifying liquid or the beneficial agent
• CPC Class Codes: A61M 16/1095 in the connecting tubes
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence

Abstract

A humidifier heats a gas to be supplied to a patient, for example, for anaesthesia in surgical operation or artificial respiration to cure difficulty of breathing, at an appropriate temperature and humidifies the same at an appropriate humidity. The humidifier calculates the absolute humidity on the basis of a set temperature and a set relative humidity by first calculating means, calculates the temperature of the gas corresponding to a saturation humidity equivalent to the calculated absolute humidity by second calculating means, controls a first heater for heating a humidifying chamber so that the temperature of the humidified gas at the outlet of the humidifying chamber coincide with the calculated temperature, and controls a second heater for heating the interior of a patient circuit connected to the outlet of the humidifier so that the temperature of the humidified gas at the outlet of the patient circuit conicides with the set temperature to prevent condensation within the patient circuit and the flow of water condensed in the patient circuit into the trachea of the patient who receives the humidified gas through the patient circuit. The humidifier is provided with display means for displaying the calculated absolute humidity to enable selection of an appropriate set temperature and an appropriate set relative humidity with reference to the absolute humidity displayed by the display means in order that the medical gas of an appropriate humidity is supplied to the patient.

Claims

1. A humidifier for humidifying a medical gas to be supplied to a patient comprising:

a humidifying chamber having an outlet through which a humidified medical gas exits said chamber;

a first heater for heating the humidifying chamber;

a first temperature sensor for detecting the temperature of the medical gas at the outlet of the humidifying chamber, a patient circuit having an interior and an outlet through which the medical gas humidified in the humidifying chamber flows;

a second heater for heating the interior of the patient circuit; and

a second temperature sensor for detecting the temperature of the humidified medical gas at the outlet of the patient circuit;

the improvement comprising;

first calculating means for calculating the absolute humidity (mg/e) of the humidified medical gas on the basis of a set temperature and a set relative humidity (%);

second calculating means for calculating the temperature of air corresponding to a saturation humidity equivalent to the calculated absolute humidity (mg/t); and

control means for controlling said first heater for heating the humidifying chamber so that the temperature of the humidified medical gas at the outlet of the humidifying chamber coincides with the temperature calculated by the second calculating means.

2. A humidifier according to claim 1, further having a display device for displaying the absolute humidity (mg/e) calculated on the basis of said set temperature and said set relative humidity (%) by said first calculating means.