Assessing the depth of isoflurane anaesthesia during cardiopulmonary bypass

Ng, Ka Ting; Alston, R. Peter; Just, George; McKenzie, Chris Anne

doi:10.1177/0267659117735883

Cited by 11 publications

(9 citation statements)

References 27 publications

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“…19,20 Both studies had almost identical methodology as the present study, but while the main study found a significant correlation between oxygenator exhaust and arterial isoflurane concentration indicating that inaccuracy in gas measurement may not have been the cause of failure to detect a correlation in the present study, the sub-study did not find a correlation. 19,20 The most important difference in methodology between the main study and the sub-study is that because patients from four anaesthetists were recruited, a range of doses of isoflurane from 1% to 2.5% was administered rather than a fixed dose of 2.5% in the sub-study because it used only patients from one anaesthetist. Thus, using a range of doses rather than a fixed dose made detecting a true signal between oxygenator exhaust and arterial blood concentrations of isoflurane possible using a small study population size.…”

Section: Discussionsupporting

confidence: 51%

“…While this finding conflicts with three, two other studies have also been unable to detect a relationship between oxygenator exhaust and arterial blood concentration of volatile anaesthetic agent. 16–20 An important weakness of this part of the present study is that several different anaesthetic gas monitor modules were used, and although the modules’ accuracy are checked annually and recalibrated if required, it cannot be excluded that they were inaccurate during the period of study and that using multiple modules introduced variance. If the study was to be repeated, then these sources of variance could be reduced by using a single gas analyser module and confirming its accuracy during the period of study.…”

Section: Discussionmentioning

confidence: 99%

“…3,15–17 However, while some studies have found an association, others have not and so it remains unclear whether oxygenator exhaust and arterial blood concentrations of volatile anaesthetic agents are truly related. 16–20…”

Section: Introductionmentioning

confidence: 99%

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The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass

et al. 2019

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Background: Administering isoflurane 2.5% into the oxygenator during cardiopulmonary bypass results in no patient movement. However, doing so may result in an excessive depth of anaesthesia particularly, when hypothermia is induced. Bispectral index and arterial blood and oxygenator exhaust concentrations of volatile anaesthetics should be related to depth of anaesthesia. The primary aim of this study was to measure the depth of anaesthesia using bispectral index, resulting from administering isoflurane 2.5% into the oxygenator during cardiopulmonary bypass, and secondary aims were to examine the relationships between blood and oxygenator exhaust isoflurane concentrations and bispectral index. Methods: Arterial and mixed-venous blood samples were aspirated at three time points during cardiopulmonary bypass and measured for isoflurane concentration using mass spectrometry. Simultaneously, oxygenator exhaust isoflurane concentration, nasopharyngeal temperature and bispectral index were recorded. Results: When averaged across the three time points, all patients had a bispectral index score below 40 (binomial test, p < 0.001). There were no significant correlations between bispectral index score and arterial or mixed-venous blood isoflurane concentrations (r = –0.082, p = 0.715; r = –0.036, p = 0.874) and oxygenator exhaust gas concentration of isoflurane (r = –0.369, p = 0.091). Conclusion: When 2.5% isoflurane was administered into the sweep gas supply to the oxygenator during cardiopulmonary bypass, all patients experienced a bispectral index score less than 40 and no significant relationship was found between either arterial or mixed-venous blood or oxygenator exhaust concentrations of isoflurane and bispectral index.

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Section: Discussionsupporting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

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The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass

et al. 2019

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“…During CPB, the concentration of the volatile anaesthetic in the oxygenator exhaust line should be monitored. 256 It has been demonstrated that this concentration correlates well with the arterial concentration, 250,260 although others dispute this. 250 During CPB, isoflurane and sevoflurane can cause hypotension by vasodilation.…”

Section: Volatile Anaestheticsmentioning

confidence: 97%

2019 EACTS/EACTA/EBCP guidelines on cardiopulmonary bypass in adult cardiac surgery

Kunst

Milojevic

Boer

et al. 2019

British Journal of Anaesthesia

136

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Special Article responsible in the event of any contradiction, discrepancy and/or ambiguity between the EACTS, EACTA and EBCP Guidelines and any other official recommendations or guidelines issued by the relevant public health authorities, in particular in relation to good use of healthcare or therapeutic strategies. Health professionals are encouraged to take the EACTS, EACTA and EBCP Guidelines fully into account when exercising their clinical judgement as well as in the determination and the implementation of preventive, diagnostic or therapeutic medical strategies; however, the EACTS, EACTA and EBCP Guidelines do not, in any way whatsoever, override the individual responsibility of health professionals to make appropriate and accurate decisions in consideration of each patient's health condition and, where appropriate and/or necessary, in consultation with that patient and the patient's care provider. Nor do the EACTS, EACTA and EBCP Guidelines exempt health professionals from giving full and careful consideration to the relevant official, updated recommendations or guidelines issued by the competent public health authorities, in order to manage each patient's case in light of the scientifically accepted data pursuant to their respective ethical and professional obligations. It is also the health professional's responsibility to verify the applicable rules and regulations relating to drugs and medical devices at the time of prescription. The article has been co-published with permission in the British Journal of Anaesthesia, the European Journal of Cardio-Thoracic Surgery and the Interactive CardioVascular and Thoracic Surgery.

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“…Recently, a nociception index (qNOX) measures the probability of the patient to respond to external noxious stimuli, and thus, providing an objective measurement of the patient’s nociception or analgesia state. 5,6 At present, many studies have focused on qCON or BIS, and similar indices monitoring for hypnotic depths, in particular for CPB, 7–9 but only a few studies have focused on monitoring for analgesic depth, 10 in particular from EEG-derived monitoring, such as the qNOX. The study hypothesized that qNOX, in combination with the qCON or BIS, can effectively reflect the analgesia and hypnosis levels, particularly, in the CPB cardiac surgery.…”

Section: Introductionmentioning

confidence: 99%

The effect of hypothermia during cardiopulmonary bypass on three electro-encephalographic indices assessing analgesia and hypnosis during anesthesia: consciousness index, nociception index, and bispectral index

et al. 2019

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The depth of anesthesia is commonly assessed in clinical practice by the patient’s clinical signs. However, during cardiopulmonary bypass and hypothermia, common symptoms of nociception such as tachycardia, hypertension, sweating, or movement have low sensitivity and specificity in the description of the patient nociception and hypnosis, in particular, detecting nociceptive stimuli. Better monitoring of the depth of analgesia during hypothermia under cardiopulmonary bypass will avoid underdosage or overdosage of analgesia, especially opioids. Induced hypothermia has a multifactorial effect on the level of analgesia and hypnosis. Thermoregulatory processes appear essential for the activation of analgesic mechanisms, ranging from a physiological strong negative affiliation between nerve conduction velocity and temperature, until significant repercussions on the pharmacological dynamics of the analgesic drugs, the latter decreasing the clearance rate with a subsequent increase in the effect-site concentrations. Under the hypothesis that deep hypothermia induces massive effects on the analgesia and hypnosis levels of the patient, we studied whether hypothermia effects were mirrored by several neuromonitoring indices: two hypnosis indices, consciousness index and bispectral index, and a novel nociception index designed to evaluate the analgesic depth. In this clinical trial, 39 patients were monitored during general anesthesia with coronary atherosclerosis cardiopathy who were elective for on-pump coronary artery bypass graft surgery under hypothermia. The changes and correlation between the consciousness index, bispectral index, and nociception index with respect to the temperature were compared in different timepoints at basic state, during cardiopulmonary bypass and after cardiopulmonary bypass. While the three neuromonitoring indices showed significant correlations with respect to the temperature, the nociception index and consciousness index showed the strongest sensitivities, indicating that these two indices could be an important means of intraoperative neuromonitoring during induced hypothermia under cardiopulmonary bypass.

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Assessing the depth of isoflurane anaesthesia during cardiopulmonary bypass

Cited by 11 publications

References 27 publications

The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass

The depth of anaesthesia associated with the administration of isoflurane 2.5% during cardiopulmonary bypass

2019 EACTS/EACTA/EBCP guidelines on cardiopulmonary bypass in adult cardiac surgery

The effect of hypothermia during cardiopulmonary bypass on three electro-encephalographic indices assessing analgesia and hypnosis during anesthesia: consciousness index, nociception index, and bispectral index

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