TCI Propofol-TCI Remifentanil Anaesthesia in Morbidly Obese Patients: The Performance of Servin's Formula During BIS/AEP-Guided Target-Controlled Infusion.

A1275 October 16, 2012 1:00:00 PM - 4:00:00 PM Room Hall C-Area I

TCI Propofol-TCI Remifentanil Anaesthesia in Morbidly Obese Patients: The Performance of Servin's Formula During BIS/AEP-Guided Target-Controlled Infusion

Alisher Agzamov, Ph.D., AbdulRaheem Al Qattan, Ph.D. Al Sabah & Zain Hospitals, Kuwait, Kuwait, Kuwait

BACKGROUND: The aim of this study was to assess the predictive performance of 'Servin's formula' for Bispectral Index and AEP index (BIS/ AEP)-guided target-controlled infusion: TCI Propofol- TCI Remifentanil in morbidly obese patients. METHODS: 210 patients (ASA physical status II-III, age 20-45 yrs.) undergoing laparoscopic bariatric surgery, were recruited. Anaesthesia was induced by using a TCI of Propofol with an initial target plasma concentration of 6 - 10 mcg/ml, and then adapted to maintain stable BIS values ranging between 35 and 45 and AEP Index values ranging between 12.5 and 22.5. A TCI Remifentanil (2.5 - 5.0 ng/ml) was added to achieve pain control and haemodynamic stability. For TCI Propofol, weight was corrected as suggested by Servin and colleagues. With ideal body weight (IBW) corrected according to formula suggested by Lemmens and colleagues. For Remifentanil, weight was corrected according to IBW. Arterial blood samples for the determination of blood Propofol concentrations were collected at different surgical times. The predictive performance of TCI Propofol was evaluated by examining performance accuracy. RESULTS: Median prediction error and median absolute prediction error were -32.5% (range -54.7%; -2.8%) and 35.1% (11.9%; 55.4%), respectively. Wobble median value was 6.0% (2.8%; 26.9%) while divergence median value was -1.8% h(-1) (-7.9; 33.8 % h(-1)). CONCLUSION: Significant bias between predicted and measured plasma Propofol concentrations was found while the low wobble values suggest that TCI Propofol system is able to maintain stable drug concentrations over time. As already suggested before, a computer simulation confirmed that the TCI system performance could be significantly improved when total body weight and BIS/ AEP Monitoring are used.

Copyright © 2012 American Society of Anesthesiologists

Propofol Anaesthesia.

What is an Anaesthesia?

TCI Propofol-TCI Remifentanil Anaesthesia in Morbidly Obese Patients: The Performance of Servin's Formula During BIS/AEP-Guided Target-Controlled Infusion.

A1275 October 16, 2012 1:00:00 PM - 4:00:00 PM Room Hall C-Area I

TCI Propofol-TCI Remifentanil Anaesthesia in Morbidly Obese Patients: The Performance of Servin's Formula During BIS/AEP-Guided Target-Controlled Infusion

Alisher Agzamov, Ph.D., AbdulRaheem Al Qattan, Ph.D. Al Sabah & Zain Hospitals, Kuwait, Kuwait, Kuwait

BACKGROUND: The aim of this study was to assess the predictive performance of 'Servin's formula' for Bispectral Index and AEP index (BIS/ AEP)-guided target-controlled infusion: TCI Propofol- TCI Remifentanil in morbidly obese patients. METHODS: 210 patients (ASA physical status II-III, age 20-45 yrs.) undergoing laparoscopic bariatric surgery, were recruited. Anaesthesia was induced by using a TCI of Propofol with an initial target plasma concentration of 6 - 10 mcg/ml, and then adapted to maintain stable BIS values ranging between 35 and 45 and AEP Index values ranging between 12.5 and 22.5. A TCI Remifentanil (2.5 - 5.0 ng/ml) was added to achieve pain control and haemodynamic stability. For TCI Propofol, weight was corrected as suggested by Servin and colleagues. With ideal body weight (IBW) corrected according to formula suggested by Lemmens and colleagues. For Remifentanil, weight was corrected according to IBW. Arterial blood samples for the determination of blood Propofol concentrations were collected at different surgical times. The predictive performance of TCI Propofol was evaluated by examining performance accuracy. RESULTS: Median prediction error and median absolute prediction error were -32.5% (range -54.7%; -2.8%) and 35.1% (11.9%; 55.4%), respectively. Wobble median value was 6.0% (2.8%; 26.9%) while divergence median value was -1.8% h(-1) (-7.9; 33.8 % h(-1)). CONCLUSION: Significant bias between predicted and measured plasma Propofol concentrations was found while the low wobble values suggest that TCI Propofol system is able to maintain stable drug concentrations over time. As already suggested before, a computer simulation confirmed that the TCI system performance could be significantly improved when total body weight and BIS/ AEP Monitoring are used.

Copyright © 2012 American Society of Anesthesiologists

Intraoperative awareness of the general anaesthesia.

Alisher Agzamov, A. M. Al Qattan, M. Bahzad.

Department of Anaesthesiology & ICU, Al Sabah & Zain Hospitals, MOH, Kuwait City, Kuwait.

The first cases of general anesthesia were already cases with awareness.

Until today, case reports of patients with awareness are published.

These published cases are likely to be the top of the iceberg, as most patients with postoperative recall do not inform their anesthesiologist.

Incidence of awareness with recall is between 0.1 and 0.2 %.

In a large multicenter-study, incidence of recall was 0.1 % without, and 0.18 % with the use of muscle relaxants.

The risk is increased with decreased doses of anesthetics, e.g. in patients with hemodynamic instability (trauma cases), patients undergoing cesarean section or cardiac surgery.

Intraoperative awareness does not necessarily cause explicit (conscious) memory.

Even in the absence of explicit memory, implicit (unconscious) memory can still have consequences for the patient.

In the worst case, it can cause post-traumatic stress disorder.

There is doubt whether patients may profit from positive suggestions given during intraoperative awareness.

Recommendations to administer benzodiazepines to prevent explicit memory must be reconsidered.

Complete neuromuscular block should be avoided whenever possible.

If a patient is thought to be aware, he should be contacted, his situation should be explained and affirming comments should be given until consciousness is lost again.

Postoperative visit should include questions about awareness and recall.

The Anaesthesiologist should not disbelieve reported recall.

Explanation of what had happened and referral to an experienced psychologist must be offered.

Thus, the incidence of severe sequelae should decrease.

The clinical use inhaled anesthetics and CO2 emissions.

The clinical use inhaled anesthetics and CO2 emissions.

Alisher I. Agzamov, AbdulRaheem Al Qattan.

Department of Anesthesiology & ICU, Al Sabah & Zain Hospitals, MOH, Kuwait City, Kuwait.

BACKGROUND: The inhaled anesthetics are recognized greenhouse gases. Calculating their impact during clinical usage will allow comparison to each other and to CO2 emissions.

METHODS: We determined infrared absorption cross-sections for desflurane, sevoflurane and isoflurane. 20 years global warming potential (GWP(20)) values for desflurane, sevoflurane, and isoflurane were then calculated using the present infrared results, and best estimate atmospheric lifetimes were determined. Used in 1 (MAC)-hour  agents was then multiplied by the calculated GWP(20) for that anesthetic, and expressed as " CO2 equivalent" (CDE(20)) in grams. Common fresh gas flows and carrier gases, both Air/O2 and N2O/O2, were considered in the calculations to allow clinical use of inhaled anesthetics.

RESULTS: GWP(20) values were: sevoflurane 348, isoflurane 1402, and desflurane 3715. CDE(20) values: sevoflurane 6981 g, isoflurane 15,6 g, and desflurane 188,2 g. Comparison among these anesthetics produced a ratio of sevoflurane 1, isoflurane 3, and desflurane 27. When 50% N2O/50% O2 replaced Air/O2 as a gas combination, and agents delivery was adjusted to deliver 1 MAC-hour of anesthetic, sevoflurane CDE(20) values were 6.1 times higher with N2O than when carried with air/O2, isoflurane values were 3.0 times higher, and desflurane values were 0.45 times lower. On a 100-year time horizon with 50% N2O, the sevoflurane CDE(100) values were 20 times higher than when carried in air/O2, isoflurane values were 10 times higher, and desflurane values were equal with and without N2O.

CONCLUSIONS: Desflurane has a potential impact on global warming than isoflurane or sevoflurane. N2O produces a greenhouse gas contribution relative to sevoflurane or isoflurane. 50% N2O combined with inhaled anesthetics increases the environmental impact of sevoflurane and isoflurane, and decreases that of desflurane. N2O is destructive to the ozone layer as well as possessing GWP; it continues to have impact over a longer timeframe, and may not be an environmentally sound tradeoff for desflurane. Our study shows that avoiding N2O and unnecessarily high fresh gas flow rates can reduce the environmental impact of inhaled anesthetics.

The recovery profiles after anaesthesia with desflurane or sevoflurane combined with TCI Propofol and TCI Remifentanil in morbidly obese patients.

The recovery profiles after anaesthesia with desflurane or sevoflurane combined with TCI Propofol and TCI Remifentanil in morbidly obese patients.

Alisher Agzamov, A. M. Al Qattan, Mohammad Al Khashti, Mohammad Behzad.

The Department of Anaesthesiology & ICU, Al Sabah & Zain Hospitals, Kuwait City, KUWAIT..

This randomized prospective study with blinded postanaesthesia care unit (PACU) observers compared the recovery profiles in morbidly obese patients who received sevoflurane or desflurane for maintenance of anaesthesia in combination with a Remifentanil target controlled infusion (TCI).

420 morbidly obese patients (BMI > 40 - 75) scheduled for laparoscopic gastric banding were included to receive AEP and BIS-guided sevoflurane or desflurane anaesthesia with AEP & BIS-triggered inhalation in combination with TCI Propofol & TCI Remifentanil. In the PACU, the following recovery scores were investigated: Modified Aldrete score, a modified Observers Assessment of Alertness/Sedation Scale (OAA/S), pain numerical rating scale (NRS), oxygen saturation (SpO(2)) and postoperative nausea and vomiting (PONV).

OAA/S and NRS pain scores showed a similar evolution in both groups from the moment of PACU admission up to 30 minutes after admission. In both groups, patients showed no serious hypoxemia during PACU stay. Incidence of PONV was shorter lasting in the sevoflurane group compared to the desflurane group.

No clinically relevant difference was found in recovery in the PACU between morbidly obese patients anesthetized with desflurane or sevoflurane. Both anesthetics gases: sevoflurane and desflurane resulted in satisfactory recovery in morbidly obese patie