Background
The objective of the present study was to validate the qCON index of hypnotic effect and the qNOX index of nociception. Both indices are derived from the frontal electroencephalogram (EEG) ...and implemented in the qCON 2000 monitor (Quantium Medical, Barcelona, Spain).
Methods
The study was approved by the local ethics committee, including data from 60 patients scheduled for ambulatory surgery undergoing general anaesthesia with propofol and remifentanil, using TCI. The Bis (Covidien, Boulder, CO, USA) was recorded simultaneously with the qCON. Loss of eyelash reflex loss of consciousness (LOC) was recorded, and prediction probability for Bis and qCON was calculated. Movement as a response to noxious stimulation laryngeal mask airway (LMA) insertion, laryngoscopy and tracheal intubation was registered. The correlation coefficient between qCON and Bis was calculated. The patients were divided into movers/non‐movers as a response to noxious stimulation. A paired t‐test was used to assess significant difference for qCON and qNOX for movers/non‐movers.
Results
The prediction probability (Pk) and the standard error (SE) for qCON and Bis for detecting LOC was 0.92 (0.02) and 0.94 (0.02) respectively (t‐test, no significant difference). The R between qCON and Bis was 0.85. During the general anaesthesia (Ce propofol > 2 μg/ml, Ce remifentanil > 2 ng/ml), the mean value and standard deviation (SD) for qCON was 45 (8), while for qNOX it was 40 (6). The qNOX pre‐stimuli values were significantly different (P < 0.05) for movers/non‐movers as a response to LMA insertion 62.5 (24.0) vs. 45.5 (24.1), tracheal intubation 58.7 (21.8) vs. 41.4 (20.9), laryngoscopy 54.1 (21.4) vs. 41.0 (20.8). There were no significant differences in remifentanil or propofol effect‐site concentrations for movers vs. non‐movers.
Conclusion
The qCON was able to reliably detect LOC during general anaesthesia with propofol and remifentanil. The qNOX showed significant overlap between movers and non‐movers, but it was able to predict whether or not the patient would move as a response to noxious stimulation, although the anaesthetic concentrations were similar.
Brachial arterial catheters better estimate aortic pressure than radial arterial catheters but are used infrequently because complications in a major artery without collateral flow are potentially ...serious. However, the extent to which brachial artery cannulation promotes complications remains unknown. The authors thus evaluated a large cohort of cardiac surgical patients to estimate the incidence of related serious complications.
The institutional Society of Thoracic Surgeons Adult Cardiac Surgery Database and Perioperative Health Documentation System Registry of the Cleveland Clinic were used to identify patients who had brachial artery cannulation between 2007 and 2015. Complications within 6 months after surgery were identified by International Classification of Diseases, Ninth Revision diagnostic and procedural codes, Current Procedural Terminology procedure codes, and Society of Thoracic Surgeons variables. The authors reviewed electronic medical records to confirm that putative complications were related plausibly to brachial arterial catheterization. Complications were categorized as (1) vascular, (2) peripheral nerve injury, or (3) infection. The authors evaluated associations between brachial arterial complications and patient comorbidities and between complications and in-hospital mortality and duration of hospitalization.
Among 21,597 qualifying patients, 777 had vascular or nerve injuries or local infections, but only 41 (incidence 0.19% 95% CI, 0.14 to 0.26%) were potentially consequent to brachial arterial cannulation. Vascular complications occurred in 33 patients (0.15% 0.10 to 0.23%). Definitely or possibly related infection occurred in 8 (0.04% 0.02 to 0.08%) patients. There were no plausibly related neurologic complications. Peripheral arterial disease was associated with increased risk of complications. Brachial catheter complications were associated with prolonged hospitalization and in-hospital mortality.
Brachial artery cannulation for hemodynamic monitoring during cardiac surgery rarely causes complications.
Depth of anaesthesia monitors might help to individualize anaesthesia by permitting accurate drug administration against the measured state of arousal of the patient. In addition, the avoidance of ...awareness or excessive anaesthetic depth might result in improved patient outcomes. Various depth of anaesthesia monitors based on processed analysis of the EEG or mid-latency auditory-evoked potentials are commercially available as surrogate measures of anaesthetic drug effect. However, not all of them are validated to the same extent.
As breast cancer screening rates increase, smaller and more numerous lesions are being identified earlier, leading to more breast-conserving surgical procedures. Achieving a clean surgical margin ...represents a technical challenge with important clinical implications. Optical coherence tomography (OCT) is introduced as an intraoperative high-resolution imaging technique that assesses surgical breast tumor margins by providing real-time microscopic images up to 2 mm beneath the tissue surface. In a study of 37 patients split between training and study groups, OCT images covering 1 cm(2) regions were acquired from surgical margins of lumpectomy specimens, registered with ink, and correlated with corresponding histologic sections. A 17-patient training set used to establish standard imaging protocols and OCT evaluation criteria showed that areas of higher scattering tissue with a heterogeneous pattern were indicative of tumor cells and tumor tissue in contrast to lower scattering adipocytes found in normal breast tissue. The remaining 20 patients were enrolled into the feasibility study. Of these lumpectomy specimens, 11 were identified with a positive or close surgical margin and 9 were identified with a negative margin under OCT. Based on histologic findings, 9 true positives, 9 true negatives, 2 false positives, and 0 false negatives were found, yielding a sensitivity of 100% and specificity of 82%. These results show the potential of OCT as a real-time method for intraoperative margin assessment in breast-conserving surgeries.
General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become ...conscious during surgery, but have no postoperative recollection of the period of consciousness.
To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries.
We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness.
At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language.
We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs.
Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.
Tissue Oximetry and Clinical Outcomes Bickler, Philip; Feiner, John; Rollins, Mark ...
Anesthesia and analgesia,
01/2017, Volume:
124, Issue:
1
Journal Article
Peer reviewed
A number of different technologies have been developed to measure tissue oxygenation, with the goal of identifying tissue hypoxia and guiding therapy to prevent patient harm. In specific cases, ...tissue oximetry may provide clear indications of decreases in tissue oxygenation such as that occurring during acute brain ischemia. However, the causation between tissue hemoglobin-oxygen desaturation in one organ (eg, brain or muscle) and global outcomes such as mortality, intensive care unit length of stay, and remote organ dysfunction remains more speculative. In this review, we describe the current state of evidence for predicting clinical outcomes from tissue oximetry and identify several issues that need to be addressed to clarify the link between tissue oxygenation and outcomes. We focus primarily on the expanding use of near-infrared spectroscopy to assess a venous-weighted mixture of venous and arterial hemoglobin-oxygen saturation deep in tissues such as brain and muscle. Our analysis finds that more work is needed in several areas: establishing threshold prediction values for tissue desaturation-related injury in specific organs, defining the types of interventions required to correct changes in tissue oxygenation, and defining the effect of interventions on outcomes. Furthermore, well-designed prospective studies that test the hypothesis that monitoring oxygenation status in one organ predicts outcomes related to other organs need to be done. Finally, we call for more work that defines regional variations in tissue oxygenation and improves technology for measuring and even imaging oxygenation status in critical organs. Such studies will contribute to establishing that monitoring and imaging of tissue oxygenation will become routine in the care of high-risk patients because the monitors will provide outputs that direct therapy to improve clinical outcomes.
Periodic, quantitative measurement of blood pressure (BP) in humans, predating the era of evidence-based medicine by over a century, is a component of the American Society of Anesthesiologists ...standards for basic anesthetic monitoring and is a staple of anesthetic management worldwide. Adherence to traditional BP parameters complicates the ability of investigators to determine whether particular BP ranges confer any clinical benefits. The BP waveform is a complex amalgamation of both antegrade and retrograde (reflected) pressure waves and is affected by vascular compliance, distance from the left ventricle, and the 3D structure of the vascular tree. Although oscillometry is the standard method of measuring BP semicontinuously in anesthetized patients and is the primary form of measurement in >80% of general anesthetics, major shortcomings of oscillometry are its poor performance at the extremes and its lack of information concerning BP waveform. Although arterial catheterization remains the gold standard for accurate BP measurement, 2 classes of devices have been developed to noninvasively measure the BP waveform continuously, including tonometric and volume clamp devices. Described in terms of a feedback loop, control of BP requires measurement, an algorithm (usually human), and an intervention. This narrative review article discusses the details of BP measurement and the advantages and disadvantages of both noninvasive and invasive monitoring, as well as the principles and algorithms associated with each technique.
A significant number of surgical patients are at risk of intra- or post-operative complications or both, which are associated with increased lengths of stay, costs, and mortality. Reducing these ...risks is important for the individual patient but also for health-care planners and managers. Insufficient tissue perfusion and cellular oxygenation due to hypovolemia, heart dysfunction or both is one of the leading causes of perioperative complications. Adequate perioperative management guided by effective and timely hemodynamic monitoring can help reduce the risk of complications and thus potentially improve outcomes. In this review, we describe the various available hemodynamic monitoring systems and how they can best be used to guide cardiovascular and fluid management in the perioperative period in high-risk surgical patients.
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