Changes In Bispectral Index Research Articles

Recovery of dynamic balance after additional small divided doses of midazolam given intravenously for sedation

We have previously reported that a dynamic balance test with perturbation stimuli and computerised dynamic posturography sensitively reflected the inhibitory effect on balance of intravenous midazolam sedation given intravenously as a single dose, and recovery time was within 80 min. The purpose of this study was to investigate the recovery of dynamic balance after additional doses of midazolam. Eighteen young adult male volunteers were sedated with midazolam given intravenously. The initial dose was given until the Wilson sedation score reached 3, and an additional dose was given until the same score was obtained 40 min later. They were tested with perturbation stimuli 40, 80, 100, and 120 min after the additional doses had been given. Their recovery time was recorded. The mean (S.D.) initial dose of midazolam was 0.07 (0.005) mg kg −1, and additional doses were 41 (7)% of the initial dose. The serial changes in bispectral index after initial and additional doses were similar. The recovery time for the dynamic balance test (within 80 min) was the same as that recorded in the previous single-dose study. The recovery time of the psychomotor function test was within 75 min. Additional doses of midazolam aiming for a Wilson sedation score of 3 at a dose about 40% of the initial dose and given 40 min after the initial dose are valid in terms of the maintenance of sedation and recovery of dynamic balance. Complete recovery time, including psychomotor function, was within 80 min of the additional dose of the drug.

Influence of the Descending Thoracic Aortic Cross Clamping on Bispectral Index Value and Plasma Propofol Concentration in Humans

In this study, the authors investigated changes in Bispectral Index (BIS) values and plasma propofol concentrations (Cp) after aortic cross clamping in the descending thoracic aortic aneurysm repair surgery during propofol anesthesia. Prospectively, in 10 patients undergoing thoracic aortic surgery during total intravenous anesthesia with propofol, BIS values were recorded during cross clamping of the descending thoracic aorta. In this study, the rate of propofol infusion was controlled to keep the BIS value between 30 and 60 throughout surgery. Simultaneously, Cp values in the blood samples taken from the right radial artery (area proximal to cross clamping) and the left femoral artery (area distal to cross clamping) were measured. Approximately 15 min after initiating aortic cross clamping, BIS values in all cases started to decrease abruptly. Cp values of samples taken from the radial artery after cross clamping of the aorta were significantly (P < 0.05) increased compared with pre-cross clamp values (1.8 +/- 0.4 microg/ml), and the mean Cp after aortic cross clamping varied between 3.0 and 5.3 microg/ml. In addition, there were significant differences in the Cp values between radial arterial and femoral arterial blood samples throughout aortic cross clamping. Cp values in samples from the radial artery were approximately two to seven times higher than those from the femoral artery. This study showed that Cp values increased and BIS values decreased rapidly after aortic cross clamping in thoracic aortic aneurysm repair surgery during propofol anesthesia. These findings suggested that all anesthesiologists should control the infusion rate carefully, taking the abrupt changes in its pharmacokinetics into consideration, especially during cross clamping of the descending thoracic aorta.

Bispectral Index Changes During Flumazenil Reverses Sedative Effect of Midazolam

目的 观察氟马西尼拮抗咪达唑仑镇静效应时脑电双频指数(BIS)的变化,并探讨氟马西尼的合理用量.方法 ASA Ⅰ或Ⅱ级成年手术患者48例,椎管内联合麻醉效果确切.手术开始时静脉持续输注咪达唑仑,保持BIS值在50～55.手术结束时按停止输注咪达唑仑后的处理方法将患者随机分成4组,每组12例.Ⅰ组不用氟马西尼;Ⅱ、Ⅲ、Ⅳ组分别静脉注射氟马西尼首量0.1、0.2、0.3mg,根据OAA/S评分结果每隔1min追加氟马西尼0.1mg,直至OAA/S评分达4分.记录应用氟马西尼首量后1、2、3、5、10、15和20 min时的BIS值和OAA/S评分.结果手术结束停止输注咪达唑仑时四组患者的BIS值保持在50～55之间,所有患者OAA/S评分均为1分.Ⅰ组停用咪达唑仑后15～20min BIS值上升到60以上,OAA/S评估达到3分.Ⅱ组给予氟马西尼后1min时,BIS均值上升到58,OAA/S评估已达到3分.Ⅲ组和Ⅳ组给予氟马西尼后1～2min时,BIS均值已超过65,OAA/S评估达到4分,恢复速度比Ⅱ组明显快(p<0.05).Ⅱ组75%的患者需追加两次氟马西尼后,BIS值和OAA/S评分才迅速恢复.结论氟马西尼能有效地拮抗咪达唑仑的镇静效应,首量0.3mg能获得迅速和完善的镇静拮抗效果。

Concomitant Assessment of Depth of Sedation by Changes in Bispectral Index and Changes in Autonomic Variables (Heart Rate and/or BP) in Pediatric Critically Ill Patients Receiving Neuromuscular Blockade

We evaluated whether or not changes in bispectral index (BIS) are associated with concomitant changes in autonomic variables that are in agreement with the different level of sedation that the changes in BIS indicate. A retrospective chart review. A pediatric ICU of a children's hospital. Charts of patients who were receiving mechanical ventilation and IV sedation, neuromuscular blockade, and continuous BIS monitoring were enrolled in the study. Changes in BIS values > or = 30% from previous readings were evaluated to determine whether or not concomitant changes of > or = 10% in autonomic variables, in the same direction, coexisted. Forty-seven patients (35 male and 12 female) were enrolled in our study; ages ranged from 10 days to 18 years (mean, 4.2 +/- 6.2 years [+/- SD]). Twenty-five patients were < 1 year of age (53%). All patients were sedated and pharmacologically paralyzed. Overall, 387 BIS readings (15%) showed a > or = 30% change from the previously documented BIS number. These BIS changes were in agreement with heart rate (HR) changes, mean arterial pressure (MAP) changes, and both HR and MAP changes in 10.6%, 23.8%, and 5.7% of the time, respectively. The same analysis of agreement was done for patients < or = 1 year old, and results were no different from those of older patients. Among 21 patients who were not receiving any vasoactive drugs (alpha- and/or beta-adrenergic agonists) during the study period, 157 BIS recordings (15%) showed a > or = 30% change from the previously documented BIS number. The percents of agreement with HR, MAP, and HR and MAP for these patients were 14.6%, 17.2%, and 7.6%, respectively. In 26 patients who were receiving vasoactive medications during the study, 230 BIS recordings (15%) showed a > or = 30% change from the previously documented BIS number. For these patients, the percentages of agreement were 7.8%, 28.3%, and 4.3%, respectively. Agreement with MAP was significantly better than with HR for this group of patients (p < 0.05; Fisher Exact Test). While significant changes in BIS are thought to reflect significant changes in depth of sedation, they have a very low rate of agreement with changes in vital signs. In the absence of BIS, the level of sedation of chemically paralyzed pediatric patients can be better guided by changes in MAP than in HR, particularly in patients receiving vasoactive drug treatment.

The relationship between bispectral index and targeted propofol concentration is biphasic in patients with major burns

Many pathophysiologic alterations in major burns can cause changes in the distribution of, and perhaps response to, drugs commonly used in anesthesia practice. This study was conducted to assess changes in bispectral index (BIS) caused by increasing the target propofol effect-site concentration during a target-controlled infusion (TCI) in major burns. Eighteen patients, ASA physical status 2 or 3, aged from 20 to 55 years old, weighing 50-70 kg, with major burns, scheduled for elective early escharectomy less than a week after injury were recruited. A further 18 ASA physical status class 1 or 2, non-burns, age, sex- and weight-matched adult patients scheduled for elective surgery under general anesthesia were recruited as controls. During anesthesia induction, target propofol effect-site concentrations were increased by increments of 0.5 microg ml(-1) up to 4.5 microg ml(-1). The BIS responses to each target concentration using TCI were compared in both groups. In the burns group, significantly greater BIS values relating to increasing propofol TCI were noted at deeper anesthesia when compared with controls; at > or =3.5 microg ml(-1); mean BIS remained at a plateau of about 50. Patients with burns had higher cardiac indices, and lower hemoglobin and albumin concentrations than the controls. They consumed more vecuronium to maintain the same degree of neuromuscular blockade than the controls. In major burns, the final biphasic BIS responses appeared to be determined by numerous other variables such as BIS algorithm, TCI performance, and altered propofol pharmacokinetics and pharmacodynamics. According to our results the importance of an individually tailored approach, including careful anesthetic titration, based upon the patient's clinical condition and responses can not be overemphasized.

Bispectral Index Changes during Anesthesia Induction with Ketamine in Children

Background: The bispectral index (BIS) is a processed EEG information that has been validated as a means to measure the hypnotic effect of anesthetic drugs. The aim of this study was to evaluate the BIS changes during anesthesia induction with ketamine in children. Methods: Eighty-four ASA class I and II pediatric patients, aged 3-8 years, were enrolled in this study. In each patient the BIS value was recorded before anesthesia induction. Without premedication, eighty-four patients received ketamine bolus, 1.0 mg/kg (Group 1, n = 28) or 1.5 mg/kg (Group 2, n = 28) or 2.0 mg/kg (Group 3, n = 28). When unresponsiveness to verbal commands (UVC) and loss of eyelash reflex (LER) were ascertained, intubation was performed after administration of succinylcholine 1.5 mg/kg and anesthesia was maintained with 2.0% enflurane and 50% N2O-50% . Results: Ketamine bolus induced UVC and LER at which the BIS values were, 92.5 5.6 and 93.9 3.0 for Group 1, 92.5 6.3 and 92.6 4.4 for Group 2, and 93.0 4.3 and 91.0 4.1 for Group 3. BIS from UVC and LER to three minutes after ketamine bolus remained above 90 for Group 1 and 2, whereas lower than Group 1 for Group 3 (P ＜ 0.05). However, the BIS for Group 3 showed above 85 as patient entered into clinical anesthetic state. Conclusions: Our study showed that there is a lack of correlation between the BIS and the anesthetic state induced by ketamine in children aged 3-8 years. Monitoring the depth of ketamine anesthesia remains difficulty.

Bispectral index changes following etomidate induction of general anaesthesia and orotracheal intubation

Etomidate-associated hypnosis has only been studied using standard clinical criteria and raw EEG variables. We conducted a BIS-based investigation of etomidate induction of general anaesthesia. Thirty hydroxyzine-premedicated ASA I patients were randomly allocated to receive etomidate 0.2, 0.3, or 0.4 mg kg(-1) intravenously over 30 s. The BIS was continuously recorded. A tourniquet was placed on a lower limb to record purposeful movements and myoclonia. Tracheal intubation was facilitated using rocuronium 0.6 mg kg(-1) when the BIS value was 50. The times to disappearance of the eyelash reflex, to a decrease in the BIS to 50, and to tracheal intubation were compared. The BIS values 30 s following tracheal intubation, and mean arterial pressure (MAP) and heart rate (HR) at all time points were also recorded. The BIS value decreased to 50 for tracheal intubation with no purposeful movement in all but one patient in the 0.2 mg kg(-1) group. There was no difference between the etomidate groups (0.2, 0.3, and 0.4 mg kg(-1)) in regards to time to loss of the eyelash reflex (103 (67), 65 (34), 116 (86) s, P=0.2), or to a decrease in BIS to 50 (135 (81), 82 (36), 150 (84) s, P=0.1). Also, the BIS value 30 s after intubation (41 (10), 37 (4), 37 (4), P=0.4), and plasma etomidate concentrations (161 [29-998], 308 [111-730], 310 [90-869] ng ml(-1), P=0.2) did not differ between groups. The time to loss of the eyelash reflex was 12-140 s shorter than the time to a decrease in BIS to 50 in three patients in each group who received etomidate 0.2 and 0.4 mg kg(-1), and in four patients who received 0.3 mg kg(-1). No awareness was recorded. MAP and HR increases following tracheal intubation were comparable between groups. Etomidate induction doses do not predict the time for BIS to decrease to 50 as this variable varies markedly following three etomidate dose regimen.

Bispectral index detects period of cerebral hypoperfusion during cardiopulmonary bypass

HE BISPECTRAL INDEX (BIS) is a processed electroencephalogram (EEG) parameter that was designed for the assessment of the depth of hypnosis or sedation and the detection of awareness. During cardiac anesthesia, BIS monitoring may be of value because the incidence of awareness is reported to be greater. 1 The authors use BIS monitoring for an anesthesia protocol, in which propofol is titrated to obtain BIS values between 50 and 40. This case report describes the use of BIS during cardiopulmonary bypass when a period of cerebral ischemia was detected with BIS monitoring. CASE REPORT A 61-year-old man (weight 93 kg, height 178 cm) was admitted for reoperation of his coronary artery bypass grafts (CABG). His first CABG was performed 16 years previously. Two years earlier he had had a myocardial infarction, congestive heart failure, and atrial fibrillation. One month before the present surgery, he complained of progressive angina pectoris (NYHA IV). Cardiac catheterization revealed occlusion of the graft to the ramus circumflex coronary artery and a 99% stenosis of the graft to the left anterior descending coronary artery. The anterior wall of the left ventricle was hypokinetic, and there was a grade II mitral valve incompetence. After placing peripheral intravenous and intra-arterial catheters, a 5-lead electrocardiogram, a pulse oximeter, and a BIS monitor (A2000, software version 1.08; Aspect Medical Systems, Newton, MA) were applied. Anesthesia was induced with an intravenous infusion of propofol at a rate of 1.86 g/h (twice body weight in mL/h). This infusion was controlled using the Rugloop (version 3.22; RUG, Gent, Belgium) computer program, which uses the pharmacokinetic model of Marsh et al. 2 The same computer program was used for data acquisition. When the patient became unresponsive to verbal command, the effect site concentration was found to be 2.0 g/mL, and, from then on, the continuous infusion mode was changed to the effect-site steering mode at that initial effect-site concentration. The effect-site concentration was thereafter adjusted to obtain a BIS value between 40 and 50. Once the patient was asleep, 10 mg of pancuronium and 1.5 g of cefuroxime were injected intravenously. A remifentanil infusion was then started at a rate of 0.33 g/kg/min, and intubation was performed 6 minutes later. From then on, the infusion rate of remifentanil was adjusted to obtain the desired systolic arterial pressure. After intubation, a pulmonary artery catheter was inserted via the right internal jugular vein, and an elevated pulmonary artery pressure (40/25 mmHg), an elevated wedge pressure (21 mmHg), and a low arterial pressure (85/55 mmHg) and cardiac index (1.8 L/min/m 2 ) were found with a spontaneous moderate recovery thereafter. The heart was not easily exposed because of adhesions and embedding in fatty tissue. Saphenous veins and the left internal mammary artery were prepared. After heparinization, the patient was put on cardiopulmonary bypass with a flow of 2.4 L/min/m 2 . The patient was cooled to a temperature of 28°C, and myocardial protection after crossclamping consisted of retrograde blood cardioplegia. Hematocrit was maintained above 22%. The mean arterial pressure was maintained between 50 and 80 mmHg, but no pharmacologic agents were used. The central venous pressure (CVP) was measured at the CVP port of the pulmonary artery catheter (distance from tip 30 cm) and was left in situ during cardiopulmonary bypass. The left marginal coronary artery was of poor quality and was ligated proximally and grafted distally with the venous graft. To obtain good access to this site of the anastomosis, the heart was twisted to the right. At this point, the CVP rose to 40 mmHg (Fig 1), and the arterial pressure decreased from 65 to 45 mmHg, leading to a severely reduced cerebral perfusion pressure. BIS values dropped from 40 to 11. The surgeon was unable to return the heart to its normal position before the anastomosis was finished. The cause of the drop in arterial pressure was not clear. No alterations in venous return or pump flow were seen at that time. The arterial pressure was restored with 20 g of intravenous norepinephrine. The BIS value returned immediately to 40. The CVP normalized after 12 minutes when the anastomosis was complete. Weaning from cardiopulmonary bypass was complicated with an elevated pulmonary artery pressure and arterial hypotension. The patient therefore received dobutamine (7 g/kg/ min), and an intra-aortic balloon pump catheter was inserted via the left femoral artery. The postoperative period was further complicated with a resternotomy for postoperative bleeding. The patient was extubated on the third postoperative day. On

Comparison of Changes in Bispectral Index and Auditory Evoked Potential Index during Endotracheal Intubation

Background: Depth of anesthesia monitoring needs a consistent and reliable measure in close to real time. The aim of this study was to compare auditory evoked potential (AEP) as determined using the autoregressive model with exogenous input (ARX-mode1) versus the bispectral index (BIS) by conventional averaging. The hypothesis of the present study was that since the ARX-mode1 extracts AEP faster than BIS, the former should be able to detect changes during the brief, intense stimulus of endotracheal intubation. Methods: Forty ASA physical status I or II patients scheduled for orthopaedic surgery were randomly assigned to 2 groups (group 1; BIS and group 2; AEP). Anesthesia was induced with target-controlled infusions of propofol. After the effect-site concentration of propofol was reached at 4l/ml, vecuronium 0.1 mg/kg was administered. The trachea was intubated 3 min after the administration of vecuronium. AAI and BIS were compared during endotracheal intubation. Results: During endotracheal intubation, the ARX-extracted AEP Index showed a significant increase (P

Skin conductance correlates with perioperative stress.

Skin conductance (SC) as a measure of emotional state or arousal may be a tool for monitoring surgical stress in anaesthesia. When an outgoing sympathetic nervous burst occurs to the skin, the palmar and plantar sweat glands are filled up, and the SC increases before the sweat is removed and the SC decreases. This creates a SC fluctuation. The purpose of this study was to measure SC during laparoscopic cholecystectomy with propofol and remifentanil anesthaesia and to evaluate whether number and amplitude of SC fluctuations correlate with perioperative stress monitoring. Eleven patients were studied nine times before, during and after anaesthesia. SC was compared to changes in stress measures such as blood pressure, heart rate, norepinephrine and epinephrine levels. SC was also compared to changes in Bispectral index (BIS). The blood pressure, epinephrine levels and norepinephrine levels were positively correlated with both the number (P < 0.001) and amplitude (P < 0.01) of the SC fluctuations. Moreover, the BIS was positively correlated with the number (P < 0.001) and amplitude (P < 0.001) of the SC fluctuations. Furthermore, during tracheal intubation, the mean levels of the number of SC fluctuations from the 11 patients had the same stress response as measured in changes of the mean levels of norepinephrine. The mean BIS did not show any stress response during tracheal intubation. Number of SC fluctuations may be a useful method for monitoring the perioperative stress.

The effect of fentanyl on hemodynamic and bispectral index changes during anesthesia induction with propofol

Study Object: To investigate the changes in hemodynamics and hypnotic levels during propofol infusion and tracheal intubation with and without fentanyl. Design: Randomized, double-blinded study. Setting: Teaching hospital. Patients: 40 ASA physical status I adult patients scheduled for elective surgery. Interventions: Patients were anesthetized with either propofol (Group P; n = 20) or 2 μ g/kg of fentanyl IV followed by propofol (Group PF; n = 20). Propofol was infused at 20 mg/kg/hr throughout the study, and tracheal intubation was performed 10 minutes after the start of propofol infusion. Measurement and Main Results: Bispectral index monitoring (BIS) progressively decreased to about 50 in both groups during infusion of propofol, but no difference was found between the two groups. After tracheal intubation, BIS significantly increased but remained below 60 in both groups. Hypertensive responses to intubation were fewer in Group PF than Group P. Conclusions: Propofol administration 20 mg/kg/hr for 10 minutes is suitable in suppressing arousal reactions to tracheal intubation, but the addition of fentanyl is required to blunt the hemodynamic responses.

Changes in Bispectral Index during Coinduction with Intravenous Anesthetics Using Synergistic Interaction

Changes in Bispectral Index during Coinduction with Intravenous Anesthetics Using Synergistic Interaction

Paradoxical changes in bispectral index during nitrous oxide administration

I report two patients undergoing open heart surgery, with nitrous oxide and isoflurane anaesthesia, for whom bispectral index (BIS) monitoring showed high BIS values with nitrous oxide and isoflurane anaesthesia. The BIS decreased immediately after nitrous oxide was stopped and increased again after nitrous oxide was restarted.

The Changes in Bispectral Index during a Hypovolemic Cardiac Arrest

The Changes in Bispectral Index during a Hypovolemic Cardiac Arrest

Comparison of the Laryngeal Mask Airway and Cuffed Oropharyngeal Airway

In Response: We appreciate the opportunity to reply to Dr. Behringer and would like to comment on each of the points raised. First, we disagree that the results between the single-institute trial [1] and the multicenter trial [2] are in "sharp contrast." In terms of ease of placement, time taken to achieve an adequate airway, first time placement success rates, airway sealing pressure, number of airway interventions required, and postoperative jaw/neck pain, both trials showed that the laryngeal mask airway (LMA) was the superior device. The main contrasting result was that the multicenter trial [2] showed that the cuffed oropharyngeal airway (COPA) had a less frequent incidence of sore throat and the single-center trial [1] showed a less frequent incidence with the LMA. We consider the postoperative data from the single-institute trial more reliable because data collection was double-blinded and the severity was graded, unlike the multicenter trial. Second, we did not make "protestations" that clinical expertise was comparable. We accurately described the experience of the investigators with both devices. Furthermore, in an attempt to measure the performance, we scored the quality of use of each device on a six-point scale using video recordings assessed by an independent investigator. We found that the score was high and similar for both devices, which suggests that both devices were being used according to the manufacturer's recommendations. We apologize for the lack of availability of the "in press" reference, which was accepted for publication by Anaesthesia in September 1997. We made no statement that "the plateau of the COPA's learning curve is reached with as few as 50 insertions." What we found was that there was no evidence of skill acquisition over the first 50 uses when comparing 25-use epochs. We therefore considered that inclusion of investigators with a minimum of 15-use experience [average >40 uses, as chosen in a recent trial [3]] to be reasonable. In the Discussion, we did state, "it is likely that performance of the COPA may improve with increasing individual experience, understanding, and application of the anatomical issues involved." Third, we accept that the use of different drug doses may favor one device or the other, but the optimal regimens are unknown for both devices, although more information is available for the LMA. From a methodological viewpoint, when comparing two devices, it is important to use the same drug regimen; otherwise, the outcome may be drug-related rather than device-related. Two recent studies have compared the response to insertion between the LMA and COPA. Nakata et al. [4] showed that the COPA required a lower minimum alveolar anesthetic concentration of sevoflurane for placement, but Versichelen et al. [3] showed similar hemodynamic and bispectral index changes after induction with propofol. Fourth, we do not consider that the maximal cuff volumes used (50 mL size 10; 60 mL size 11) contributed to the poor performance of the COPA. These volumes were recommended to us by the manufacturer for an earlier study and have since been revised. In our experience, higher volumes do not provide a better seal and are associated with unacceptably high in vivo intracuff pressures. Finally, we agree that the COPA deserves more careful scrutiny to fully define its appropriate clinical usage. However, a finding common to all published reports is that the COPA is not a consistently hands-free device. J. R. Brimacombe, MB ChB, FRCA, MD J. C. Brimacombe, BSc Department of Anaesthesia and Intensive Care; Cairns Base Hospital; Cairns, Australia A. M. Berry, MB ChB, FRCA Department of Anaesthesia and Intensive Care; Nambour General Hospital; Nambour, Australia

Comparison of the Laryngeal Mask Airway and Cuffed Oropharyngeal Airway

In Response: We appreciate the opportunity to reply to Dr. Behringer and would like to comment on each of the points raised. First, we disagree that the results between the single-institute trial [1] and the multicenter trial [2] are in "sharp contrast." In terms of ease of placement, time taken to achieve an adequate airway, first time placement success rates, airway sealing pressure, number of airway interventions required, and postoperative jaw/neck pain, both trials showed that the laryngeal mask airway (LMA) was the superior device. The main contrasting result was that the multicenter trial [2] showed that the cuffed oropharyngeal airway (COPA) had a less frequent incidence of sore throat and the single-center trial [1] showed a less frequent incidence with the LMA. We consider the postoperative data from the single-institute trial more reliable because data collection was double-blinded and the severity was graded, unlike the multicenter trial. Second, we did not make "protestations" that clinical expertise was comparable. We accurately described the experience of the investigators with both devices. Furthermore, in an attempt to measure the performance, we scored the quality of use of each device on a six-point scale using video recordings assessed by an independent investigator. We found that the score was high and similar for both devices, which suggests that both devices were being used according to the manufacturer's recommendations. We apologize for the lack of availability of the "in press" reference, which was accepted for publication by Anaesthesia in September 1997. We made no statement that "the plateau of the COPA's learning curve is reached with as few as 50 insertions." What we found was that there was no evidence of skill acquisition over the first 50 uses when comparing 25-use epochs. We therefore considered that inclusion of investigators with a minimum of 15-use experience [average >40 uses, as chosen in a recent trial [3]] to be reasonable. In the Discussion, we did state, "it is likely that performance of the COPA may improve with increasing individual experience, understanding, and application of the anatomical issues involved." Third, we accept that the use of different drug doses may favor one device or the other, but the optimal regimens are unknown for both devices, although more information is available for the LMA. From a methodological viewpoint, when comparing two devices, it is important to use the same drug regimen; otherwise, the outcome may be drug-related rather than device-related. Two recent studies have compared the response to insertion between the LMA and COPA. Nakata et al. [4] showed that the COPA required a lower minimum alveolar anesthetic concentration of sevoflurane for placement, but Versichelen et al. [3] showed similar hemodynamic and bispectral index changes after induction with propofol. Fourth, we do not consider that the maximal cuff volumes used (50 mL size 10; 60 mL size 11) contributed to the poor performance of the COPA. These volumes were recommended to us by the manufacturer for an earlier study and have since been revised. In our experience, higher volumes do not provide a better seal and are associated with unacceptably high in vivo intracuff pressures. Finally, we agree that the COPA deserves more careful scrutiny to fully define its appropriate clinical usage. However, a finding common to all published reports is that the COPA is not a consistently hands-free device. J. R. Brimacombe, MB ChB, FRCA, MD J. C. Brimacombe, BSc Department of Anaesthesia and Intensive Care; Cairns Base Hospital; Cairns, Australia A. M. Berry, MB ChB, FRCA Department of Anaesthesia and Intensive Care; Nambour General Hospital; Nambour, Australia