Method and apparatus for inhalation of treating gas and sampling of exhaled gas for quantitative analysis

A method for monitoring end tidal CO.sub.2 in unintubated, conscious, spontaneously breathing patients who are receiving administration of local and regional anesthesia or during recovery from residual general anesthesia consisting of the steps of:

• providing a nasal cannula on a patient, said cannula having an elongated hollow body;
• a gas-tight partition in said hollow body to divide said hollow body into a first zone and a second zone separated from each other by said gas tight partition;
• supply means including first conduit means communicating with said first zone and a source of oxygen, insufflation means, including second conduit means, communicating with said second zone and providing a means for detecting and measuring the partial pressure of carbon dioxide, said elongated hollow body in addition containing separate hollow nasal prongs each communicating with one of said first and second zones and with respectively each nostril of the patient;
• supplying oxygen to said patient from said source of oxygen through said first conduit means to said first zone of said elongated hollow body and into the patient's nostril through one of said nasal prong means;
• withdrawing carbon dioxide from said patient through the other of said nasal prongs into said second zone of said elongated hollow body, through said second conduit means and into said means for detecting and measuring the partial pressure of carbon dioxide;
• and
• determining the partial pressure of carbon dioxide at the end of the patient's exhalation to obtain a clinical approximation of the partial pressure of arterial carbon dioxide.