Method and an apparatus for pulse plethysmograph based detection of nociception during anesthesia or sedation

A method for monitoring a condition of a patient under anesthesia or sedation, the method comprising the steps of:

• acquiring a pulse wave signal representing peripheral cardiovascular flow in the patient;
• detecting successive heart beat pulses in said signal;
• measuring predetermined pulse wave parameters repeatedly in said signal within said successive heart beat pulses;
• comparing said predetermined pulse wave parameters in a number of successive heart beat pulses, and if a substantial alteration is occurred:
• calculating a statistical reference value by deriving values from at least said predefined pulse wave parameters;
• quantifying change(s) between at least one predefined pulse wave parameter and said reference value;
• and
• displaying and/or recording said change(s) or lack of change(s) respectively in said at least one predefined pulse wave parameter.

An apparatus for monitoring a condition of a patient under anaesthesia or sedation, the apparatus comprising:

• a photoplethysmographic or a pulse oximeter sensor for receiving a substantially continuous electrical signal representing a cardiovascular flow of the patient;
• time measuring means and a voltage/current dependent circuit connected with said sensor means;
• first memory means storing criteria of predetermined pulse wave parameter(s);
• first calculation means and/or selection means connected to said first memory means, said voltage/current dependent circuit for detecting predefined pulse wave parameter(s) of said predetermined pulse wave parameter(s) in said signal;
• quantifying means providing quantified change(s) of at least one predefined pulse wave parameter in respect to values of said predefined pulse wave parameter prior to the present moment;
• and
• a display and/or connections into other possible devices.