This study concerns the clinical evaluation of a closed loop control system for the automatic administration of anesthetic drugs in TIVA (Total Intra Venous Anesthesia). The purpose of the experimentation is to demonstrate that the control system under study is reliable, safe, applicable and capable of inducing and maintaining an optimal anesthetic level.
This clinical study consists of the application of the ACTIVA control software for the infusion of intravenous drugs during general anesthesia according to the principle of closed-loop anesthesia. The objective of the experimentation is to evaluate the reliability, safety and applicability of the infusion system for anesthetic drugs controlled by the ACTIVA software and to carry out the clinical evaluation of the automatic control system during the induction and maintenance of general intravenous anesthesia. The benefits for enrolled patients could be linked to greater stability of anesthesia in the induction and maintenance phases. Constant closed-loop control of infusions and the level of hypnosis could also reduce the hemodynamic impact that general anesthesia has on the patient, by reducing the onset of hypotension episodes. Enrolled patients will undergo closed-loop anesthesia under the constant supervision of the investigator. The anesthetic drugs used are those recommended for general intravenous anesthesia: propofol and remifentanil. Identification and description of the medical device: The medical device object of the clinical investigation consists of the ACTIVA control software developed to control the infusion of anesthetic drugs during general intravenous anesthesia. ACTIVA software has been developed to optimize the infusion of anesthetic drugs according to a closed-loop system that allows the induction and maintenance of a constant and optimal level of anesthesia on the patient. ACTIVA control software is installed on a personal computer (PC). The level of anesthesia is measured according to the Bispectral Index (BIS) which measures the depth of hypnosis. Through the measurement of the BIS, the administration of anesthetic drugs is automatically regulated by the ACTIVA software and constantly supervised by the anesthesiologist through the graphic interface integrated in the software. The population for which the device is intended is made up of patients to undergo surgery for which general anesthesia is required, and intravenous anesthesia may be advantageous. During its operation, the ACTIVA software maintains the desired BIS level, selected by the anesthesiologist through the graphical user interface, communicating the appropriate infusion rate of the propofol and remifentanil anesthetic drugs to the syringe pumps. ACTIVA software communicates with the pumps and the BIS monitoring system with serial connections. These connections are native to the instrumentation used; therefore, no type of modification or manipulation has been made on the medical devices used. Closed-loop anesthesia: A closed-loop system can be defined as an automatic control system that bases its operation on the principle of feedback. Its key elements are a system to be controlled, a measuring device (sensor), a controller and an actuator. The sensor measures the controlled variable (system output), which is compared with the desired set-point. The difference between the latter and the output, defined as an error, is used to calculate the value of the control variable (system input). In the case of closed-loop anesthesia, the system to be controlled identifies with the patient, the actuator is represented by the syringe pump, the controlled variable corresponds to the BIS and the control variable is represented by the rate of infusion of the drugs. The controller used is a proportional-integral-derivative (PID) it relates the error signal and the control variable by means of three constants (Kp, Ti and Td) allowing a correct infusion of the drugs considering the present value of the error ( proportional action), the past values of the error (integral action) and the advance of the future values of the error (derivative action). These three constants, if properly calibrated, allow to obtain a controller with good performance and robustness. For the ACTIVA system the calibration of these constants was carried out by means of optimization methods performed in simulation. The anesthesiologist has at his disposal a PC with a graphical user interface through which he can control the start and end of the drug infusion and on which there are the commands through which it is possible to interact with the system. The graphical interface also reports indicators concerning the correct functioning of the control system. In case of malfunction of the ACTIVA software, the patient monitoring systems are never altered or damaged and the infusive pumps continue to operate in manual mode. Switching to manual control is always possible if the anesthesiologist considers it appropriate, even without the presence of system malfunctions.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
139
Total intravenous anesthesia performed with the ACTIVA automatic control system
Azienda Socio Sanitaria Territoriale degli Spedali Civili di Brescia
Brescia, Italy
Depth of Hypnosis Adequacy
The depth of hypnosis adequacy is assessed by evaluating, for each patient enrolled, the percentage of maintenance duration during which the Bispectral Index Scale (BIS) is kept within the recommended range from 40 to 60 (BIS \[40,60\]). The outcome measure is defined as the median of these percentages calculated over all the patients enrolled in the study. The median of the percentages, calculated over all the patients enrolled in the study, of the anesthesia maintenance duration in which the BIS is kept below 40 (BIS\<40) is also specified. Maintenance duration is the period of time that goes from the end of anesthesia induction to the point at which the automatic control is turned off at the conclusion of surgery. The end of anesthesia induction is defined as the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds. The BIS ranges from 0 (absence of brain activity) to 100 (fully awake patient).
Time frame: During anesthesia from the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds to the point at which the automatic control is turned off (maintenance duration), an average of 2 hours.
Number of Participants for Which the System Showed Dysfunctions
Number of participants for which the ACTIVA system showed dysfunctions. The results are presented in a table where each row indicates the type of dysfunction and the number of participants for which that particular type of dysfunction occurred.
Time frame: During anesthesia from the time instant when the automatic control is started to the point at which the automatic control is turned off at the conclusion of surgery, an average of 2 hours.
Levels of Satisfaction of the Experimenter Expressed as Number of Participants Who Have Received a Specific Score
Levels of satisfaction of the experimenter regarding three aspects of the ACTIVA system. The first aspect is the ease of use of the ACTIVA software and its infusion system. The second aspect is the behavior of the ACTIVA system during the induction phase of anesthesia. The third aspect is the behavior of the ACTIVA system during the maintenance phase of anesthesia. For each aspect, the level of satisfaction is expressed by the experimenter by assigning a score on a scale ranging from 0 (extremely unsatisfied) to 10 (extremely satisfied). Thus, higher values represent a better outcome. Note that the scoring scale employed is the same for each of the three aspects. The results are reported in a table divided in three rows, one for each aspect evaluated. Each row is divided in eleven categories representing the scores from 0 to 10. For each category it is indicated the number of patients for which the experimenter expressed that specific score.
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Time frame: During anesthesia from the time instant when the automatic control is started to the point at which the automatic control is turned off at the conclusion of surgery, an average of 2 hours.
Effect of Drugs Delivery on Heart Rate
The effect of drugs delivery on heart rate is assessed by evaluating, for each patient enrolled, the percentage of the anesthesia maintenance duration in which the heart rate (HR) is kept inside the range from 50 to 100 beats per minute (HR \[50,100\]). The outcome measure is defined as the median of these percentages calculated over all the patients enrolled in the study. The median of the percentages, calculated over all the patients enrolled in the study, of the anesthesia maintenance duration in which the HR is kept below 50 (HR\<50) is also specified. Maintenance duration is the period of time that goes from the end of anesthesia induction to the point at which the automatic control is turned off at the conclusion of surgery. The end of anesthesia induction is defined as the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds.
Time frame: During anesthesia from the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds to the point at which the automatic control is turned off (maintenance duration), an average of 2 hours.
Effect of Drugs Delivery on Mean Arterial Pressure (MAP)
The effect of drugs delivery on mean arterial pressure (MAP) is assessed by evaluating, for each patient enrolled, the anesthesia maintenance duration in which the non-invasively measured MAP is kept inside the range from 65 to 110 mmHg (MAP \[65,110\]). The outcome measure is defined as the median of these percentages calculated over all the patients enrolled in the study. The median of the percentages, calculated over all the patients enrolled in the study, of the anesthesia maintenance duration in which the MAP is kept below 65 (MAP\<65) is also specified. Maintenance duration is the period of time that goes from the end of anesthesia induction to the point at which the automatic control is turned off at the conclusion of surgery. The end of anesthesia induction is defined as the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds. MAP is defined as diastolic pressure + 1/3(systolic pressure - diastolic pressure).
Time frame: During anesthesia from the time instant when the BIS drops below 60 for the first time and remains there for the subsequent 30 seconds to the point at which the automatic control is turned off (maintenance duration), an average of 2 hours.
Postoperative Heart Rate Stability
The postoperative heart rate is assessed by measuring the heart rate in beats per minute (bpm).
Time frame: End of anesthesia (operating room discharge, recovery room admission, recovery room discharge), 6 hours after surgery, 24 hours after surgery.
Postoperative Mean Arterial Pressure (MAP) Stability
The postoperative mean arterial pressure (MAP) stability is assessed by non-invasively measuring the MAP with an electronic sphygmomanometer trough an inflatable cuff. Mean arterial pressure (MAP) is defined as diastolic pressure + 1/3(systolic pressure - diastolic pressure).
Time frame: End of anesthesia (operating room discharge, recovery room admission, recovery room discharge), 6 hours after surgery, 24 hours after surgery.
Postoperative Sedation Expressed as Number of Participants Who Have Received a Specific Score
The postoperative sedation is assessed by means of a Sedation Score scale. It is a 3 point scale from 0 (fully awake) to 3 (fully sedated)
Time frame: End of anesthesia (operating room discharge, recovery room admission, recovery room discharge), 6 hours after surgery, 24 hours after surgery.
Postoperative Nausea and Vomiting (PONV) Expressed as Number of Participants Who Have Received a Specific Score
Postoperative Nausea and Vomiting is assessed by means of the Bellville PONV scale. It is a 3 point scale from 0 (no nausea \& vomiting) to 3 (vomiting present)
Time frame: End of anesthesia (operating room discharge, recovery room admission, recovery room discharge), 6 hours after surgery, 24 hours after surgery.
Postoperative Analgesia Expressed as Number of Participants Who Have Received a Specific Score
The postoperative analgesia is assessed using a 10-point numeric rating scale (NRS). It is a 10 point scale from 0 (no pain) to 10 (maximum pain).
Time frame: End of anesthesia (operating room discharge, recovery room admission, recovery room discharge), 6 hours after surgery, 24 hours after surgery.