The World Federation of Societies of Anaesthesiologists Minimum Capnometer Specifications 2021-A Guide for Health Care Decision Makers.

Capnometry, the measurement of respiratory carbon dioxide, is regarded as a highly recommended safety technology in intubated and nonintubated sedated and/or anesthetized patients. Its utility includes confirmation of initial and ongoing placement of an airway device as well as in detecting gas exchange, bronchospasm, airway obstruction, reduced cardiac output, and metabolic changes. The utility applies prehospital and throughout all phases of inhospital care. Unfortunately, capnometry devices are not readily available in many countries, especially those that are resource-limited. Constraining factors include cost, durability of devices, availability of consumables, lack of dependable power supply, difficulty with cleaning, and maintenance. There is, thus, an urgent need for all stakeholders to come together to develop, market, and distribute appropriate devices that address costs and other requirements. To foster this process, the World Federation of Societies of Anaesthesiologists (WFSA) has developed the "WFSA-Minimum Capnometer Specifications 2021." The intent of the specifications is to set the minimum that would be acceptable from industry in their attempts to reduce costs while meeting other needs in resource-constrained regions. The document also includes very desirable and preferred options. The intent is to stimulate interest and engagement among industry, clinical providers, professional associations, and ministries of health to address this important patient safety need. The WFSA-Minimum Capnometer Specifications 2021 is based on the International Organization for Standardization (ISO) capnometer specifications. While industry is familiar with such specifications and their presentation format, most clinicians are not; therefore, this article serves to more clearly explain the requirements. In addition, the specifications as described can be used as a purchasing guide by clinicians.

Best Practices in Facial Nerve Monitoring.

OBJECTIVES/HYPOTHESIS: Facial nerve monitoring (FNM) has evolved into a widely used adjunct for many surgical procedures along the course of the facial nerve. Even though majority opinion holds that FNM reduces the incidence of iatrogenic nerve injury, there are few if any studies yielding high-level evidence and no practice guidelines on which clinicians can rely. Instead, a review of the literature and medicolegal cases reveals significant variations in methodology, training, and clinical indications. STUDY DESIGN: Literature review and expert opinion. METHODS: Given the lack of standard references to serve as a resource for FNM, we assembled a multidisciplinary group of experts representing more than a century of combined monitoring experience to synthesize the literature and provide a rational basis to improve the quality of patient care during FNM. RESULTS: Over the years, two models of monitoring have become well-established: 1) monitoring by the surgeon using a stand-alone device that provides auditory feedback of facial electromyography directly to the surgeon, and 2) a team, typically consisting of surgeon, technologist, and interpreting neurophysiologist. Regardless of the setting and the number of people involved, the reliability of monitoring depends on the integration of proper technical performance, accurate interpretation of responses, and their timely application to the surgical procedure. We describe critical steps in the technical set-up and provide a basis for context-appropriate interpretation and troubleshooting of recorded signals. CONCLUSIONS: We trust this initial attempt to describe best practices will serve as a basis for improving the quality of patient care while reducing inappropriate variations. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:S1-S42, 2021.

Intraoperative optical coherence tomography in the full-thickness macular hole surgery with internal limiting membrane inverted flap placement.

PURPOSE: To describe the helpfulness of using intraoperative optical coherence tomography (OCT) during surgery for full-thickness macular hole (FTMH). OBSERVATIONS: This observational case series identifies three patients with FTMH who were treated with vitrectomy, internal limiting membrane (ILM) peel with inverted ILM flap, which was tucked into the MH, and air with 18% Sulfur Hexafluoride (SF6) gas tamponade. Intraoperative OCT was used to confirm positioning of the ILM flap, even after complete air-fluid exchange. The patients were followed for three months after surgery and all reached a good morphological and functional outcome. CONCLUSIONS: If confirmed by a prospective longitudinal study, the intraoperative OCT might become an important tool in assisting FTMH surgery.

Handgrip dynamometry for continuous assessment of volitional control during induction of anesthesia: a prospective observational study.

PURPOSE: Response to commands is the gold standard to assess the level of consciousness during anesthesia induction but it only provides an intermittent, binary measure with low temporal resolution. To overcome these limitations, we combined the object hold method with handgrip dynamometry to continuously record the force applied to hold a dynamometer as a surrogate measure of the level of consciousness during induction of anesthesia. METHODS: Fourteen patients scheduled for elective lumbar surgery and 14 age-matched non-anesthetized controls were enrolled. The subjects held the dynamometer with their dominant hand for as long as possible (patients) or until told to stop (controls). After a one-minute baseline, propofol was infused (1.0 mg·kg-1·min-1) to the patient group until the subject dropped the dynamometer, which defined the object hold time. Three additional patients were also asked intermittently to squeeze the dynamometer during the propofol infusion to determine any retained ability to exert a strong grip despite any grip changes during induction. RESULTS: The mean (standard deviation) object hold time was 115 (22) seconds after the start of the propofol infusion. There was a progressive significant linear decrease (R2 = 0.98; P < 0.001) in dynamometry-determined handgrip force starting approximately 74 seconds before object drop. Age was inversely related to the object hold time (R2 = 0.47, P < 0.01). The three additional propofol induction patients had strong intermittent grip strength despite progressive decreases in the hold force. Of the 17 patients who completed the object hold task (14 with the standard protocol and three with intermittent squeeze requests), 16 (94%; 95% confidence interval, 76 to 99%) did not respond to verbal commands after dropping the dynamometer. CONCLUSION: Handgrip dynamometry can be used to continuously track volitional control during induction of anesthesia while also reliably showing a gradual loss of consciousness. This method could be useful for studies investigating mechanisms of anesthesia.

Cardiac output measurements during high-risk Cesarean section using electrical bioreactance or arterial waveform analysis: assessment of agreement.

OBJECTIVE: Maternal hemodynamics change significantly during Cesarean section complicated by massive hemorrhage or severe hypertensive disease. Cardiac output (CO) monitoring aids early, goal-directed hemodynamic therapy. The aim of this study was to record hemodynamic changes observed during Cesarean section in pregnancies at high risk of hemodynamic instability, using invasive (LiDCOrapid™) and non-invasive (NICOM®) devices, and to assess agreement between the two devices in measuring CO. METHODS: Simultaneous intraoperative hemodynamic measurements were taken using the LiDCOrapid and NICOM devices, following standardized techniques, in women at high risk of hemodynamic instability undergoing Cesarean section. Agreement in CO measurements between the two devices was assessed using Bland-Altman plots and the agreement:tolerability index (ATI). Agreement analyses were performed for repeated measures in subjects, using centiles. RESULTS: From 10 women, 307 paired measurements were analyzed. Mean bias (defined as the mean difference in CO measurements between the LiDCOrapid and NICOM devices) was 3.05 (95% CI, 1.89 to 4.21) L/min. Limits of agreement ranged from -1.58 (95% CI, -4.47 to -0.14) to 7.68 (95% CI, 6.24 to 10.56) L/min. The resulting agreement interval was 9.26 L/min which returned an ATI of 2.3. CONCLUSIONS: There are large mean differences between CO measurements obtained during Cesarean section using the LiDCOrapid and NICOM hemodynamic monitors in pregnant women at high risk of hemodynamic instability, indicating that they should not be considered interchangeable clinically. There is an unacceptably low level of agreement (ATI > 2) in CO measurements between the devices, conferring a high risk of clinical misclassification during massive hemorrhage. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Clinical Utility of Intraoperative Tympanomastoidectomy Assessment Using a Surgical Microscope Integrated with an Optical Coherence Tomography.

Significant technical and optical advances are required for intraoperative optical coherence tomography (OCT) to be utilized during otological surgeries. Integrating OCT with surgical microscopy makes it possible to evaluate soft tissue in real-time and at a high resolution. Herein, we describe an augmented-reality, intraoperative OCT/microscope system with an extended working distance of 280 mm, providing more space for surgical manipulation than conventional techniques. We initially performed ex vivo experiments to evaluate system performance. In addition, we validated the system by performing preliminary clinical assessments of tympanomastoidectomy outcomes in six patients with chronic otitis media. The system evaluated residual inflammation in the region-of-interest of the mastoid bone. Most importantly, the system intraoperatively revealed the connection between the graft and the remnant tympanic membrane. The extended working distance allows otological surgeons to evaluate the status of both the mastoid bone and tympanic membrane during manipulation, affording full intraoperative imaging.

Assessment of changes in blood glucose concentration with intravascular microdialysis.

Blood glucose and its variability of is a major prognostic factor associated with morbidity. We hypothesized that intravenous microdialysis incorporated in a central venous catheter (CVC) would be interchangeable with changes in blood glucose measured by the reference method using a blood gas analyzer. Microdialysis and central venous blood glucose measurements were simultaneously recorded in high-risk cardiac surgical patients. The correlation between absolute values was determined by linear regression and the Bland-Altman test for repeated measurements was used to compare bias, precision, and limits of agreement. Changes in blood glucose measurement were evaluated by four-quadrant plot and trend interchangeability methods (TIM). In the 23 patients analyzed, the CVC was used as part of standard care with no complications. The correlation coefficient for absolute values (N = 99) was R = 0.91 (P < 0.001). The bias, precision and limits of agreement were - 9.1, 17.4 and - 43.2 to 24.9 mg/dL, respectively. The concordance rate for changes in blood glucose measurements (N = 77) was 85% with the four-quadrant plot. The TIM showed that 14 (18%) changes of blood glucose measurements were uninterpretable. Among the remaining 63 (82%) interpretable changes, 23 (37%) were interchangeable, 13 (20%) were in the gray zone, and 27 (43%) were not interchangeable. Microdialysis using a CVC appears to provide imprecise absolute blood glucose values with risk of insulin misuse. Moreover, only one third of changes in blood glucose measurements were interchangeable with the reference method using the TIM.

Intraoperative Assessment of the Relationship Between Nipple Circulation and Incision Site in Nipple-Sparing Mastectomy With Implant Breast Reconstruction Using the SPY Imaging System.

INTRODUCTION: Nipple-sparing mastectomy (NSM) and immediate breast reconstruction with gel implants have grown in popularity because of superior aesthetic outcomes. One risk of this procedure is overexcision of the flap leading to inadequate circulation in the breast envelope. METHODS: We investigated 17 cases of NSM and gel implant breast reconstruction. Patients were divided into an infra-areolar incision group and a supra-areolar incision group. Nipple-areolar complex perfusion was evaluated using the SPY imaging system after NSM and gel implant breast reconstruction. We aimed to discover any relationships between the incision method and nipple-areolar complex (NAC) circulation in NSM and gel implant breast reconstruction. RESULTS: For successful breast surgery, awareness of the blood supply to the breast, especially the NAC, is very important. In our study, with the indocyanine green SPY imaging system, most ingress (arterial inflow) and egress (venous outflow) rates in the infra-areolar incision group were better than those in the supra-areolar incision group (P < 0.005). CONCLUSIONS: We have shown that an infra-areolar incision provides better blood flow following NSM and gel implant breast reconstruction. In our experience, in order to prevent the possible ischemia of NAC, we used the smaller gel implants, which is approximately 10 to 20 mL smaller than the original implant size measured by the sizer, if the egress rate of NAC is lower than 0.2. These findings have implications in the clinical setting as surgeons have a choice to provide a better outcome for patients.

The Technology of Processed Electroencephalogram Monitoring Devices for Assessment of Depth of Anesthesia.

Commercial brain function monitors for depth of anesthesia have been available for more than 2 decades; there are currently more than 10 devices on the market. Advances in this field are evidenced by updated versions of existing monitors, development of new monitors, and increasing research unveiling the mechanisms of anesthesia on the brain. Electroencephalography signal processing forms an integral part of the technology supporting the brain function monitors for derivation of a depth-of-anesthesia index. This article aims to provide a better understanding of the technology and functionality behind these monitors. This review will highlight the general design principles of these devices and the crucial stages in electroencephalography signal processing and classification, with a focus on the key mathematical techniques used in algorithm development for final derivation of the index representing anesthetic state. We will briefly discuss the advantages and limitations of this technology in the clinical setting as a tool in our repertoire used for optimizing individualized patient care. Also included is a table describing 10 available commercial depth-of-anesthesia monitors.

Influence of Fraction of Inspired Oxygen on Noninvasive Hemoglobin Measurement: Parallel Assessment of 2 Monitors.

BACKGROUND: Previous reports have brought specific attention to the relationship between oxygenation of the patient and the accuracy of noninvasive measurement of hemoglobin (Hb) using an optical sensor. This study aimed to assess prospectively the relationship between fraction of inspired oxygen (FIO2) and the bias of the measurement of Hb by the use of 2 different noninvasive monitors compared with the classic invasive technique. METHODS: Forty-four patients were included prospectively. In each individual, Hb level was determined noninvasively by monitor Pronto-7™ (Masimo Corporation, Irvine, CA) and by monitor NBM-200MP™ (OrSense Ltd, Petah-Tikva, Israel), with the probe placed on 2 fingers on the same hand of the patient. Three measures were performed, first under breathing air and 2 others when fraction of expired oxygen rose to 50% ± 5% and to 90 ± 5%. Simultaneously, a nurse collected a venous blood sample, which was sent immediately to the hematology laboratory for Hb measurement. The main outcome measurement was the mean bias between noninvasive and invasive measurements. RESULTS: Results show no change in median bias [interquartile range] with FIO2 for Pronto-7 (from 1.1 g/dL [0.0-2.0] in FIO2 21% to 1.0 g/dL [0.2-1.5] in FIO2 100%), but increasingly negative median bias with increasing FIO2 for NBM-200MP (from -0.3 g/dL [-1.3 to 0.3] in FIO2 21% to -0.8 g/dL [-1.5 to -0.1] in FIO2 100%, P = .04). DISCUSSION: This study showed that noninvasive measurement of Hb could be influenced by inspired fraction of oxygen when the monitor NBM-200MP is used.

Precision diagnosis: a view of the clinical decision support systems (CDSS) landscape through the lens of critical care.

Improving diagnosis and treatment depends on clinical monitoring and computing. Clinical decision support systems (CDSS) have been in existence for over 50 years. While the literature points to positive impacts on quality and patient safety, outcomes, and the avoidance of medical errors, technical and regulatory challenges continue to retard their rate of integration into clinical care processes and thus delay the refinement of diagnoses towards personalized care. We conducted a systematic review of pertinent articles in the MEDLINE, US Department of Health and Human Services, Agency for Health Research and Quality, and US Food and Drug Administration databases, using a Boolean approach to combine terms germane to the discussion (clinical decision support, tools, systems, critical care, trauma, outcome, cost savings, NSQIP, APACHE, SOFA, ICU, and diagnostics). References were selected on the basis of both temporal and thematic relevance, and subsequently aggregated around four distinct themes: the uses of CDSS in the critical and surgical care settings, clinical insertion challenges, utilization leading to cost-savings, and regulatory concerns. Precision diagnosis is the accurate and timely explanation of each patient's health problem and further requires communication of that explanation to patients and surrogate decision-makers. Both accuracy and timeliness are essential to critical care, yet computed decision support systems (CDSS) are scarce. The limitation arises from the technical complexity associated with integrating and filtering large data sets from diverse sources. Provider mistrust and resistance coupled with the absence of clear guidance from regulatory bodies further retard acceptance of CDSS. While challenges to develop and deploy CDSS are substantial, the clinical, quality, and economic impacts warrant the effort, especially in disciplines requiring complex decision-making, such as critical and surgical care. Improving diagnosis in health care requires accumulation, validation and transformation of data into actionable information. The aggregate of those processes-CDSS-is currently primitive. Despite technical and regulatory challenges, the apparent clinical and economic utilities of CDSS must lead to greater engagement. These tools play the key role in realizing the vision of a more 'personalized medicine', one characterized by individualized precision diagnosis rather than population-based risk-stratification.

Automated, continuous and non-invasive assessment of pulse pressure variations using CNAP® system.

Non-invasive respiratory variations in arterial pulse pressure using infrared-plethysmography (PPVCNAP) are able to predict fluid responsiveness in mechanically ventilated patients. However, they cannot be continuously monitored. The present study evaluated a new algorithm allowing continuous measurements of PPVCNAP (PPVCNAPauto) (CNSystem, Graz, Austria). Thirty-five patients undergoing vascular surgery were studied after induction of general anaesthesia. Stroke volume was measured using the VigileoTM/FloTracTM. Invasive pulse pressure variations were manually calculated using an arterial line (PPVART) and PPVCNAPauto was continuously displayed. PPVART and PPVCNAPauto were simultaneously recorded before and after volume expansion (500 ml hydroxyethylstarch). Subjects were defined as responders if stroke volume increased by ≥15 %. Twenty-one patients were responders. Before volume expansion, PPVART and PPVCNAPauto exhibited a bias of 0.1 % and limits of agreement from -7.9 % to 7.9 %. After volume expansion, PPVART and PPVCNAPauto exhibited a bias of -0.4 % and limits of agreement from -5.3 % to 4.5 %. A 14 % baseline PPVART threshold discriminated responders with a sensitivity of 86 % (95 % CI 64-97 %) and a specificity of 100 % (95 % CI 77-100 %). Area under the receiver operating characteristic (ROC) curve for PPVART was 0.93 (95 % CI 0.79-0.99). A 15 % baseline PPVCNAPauto threshold discriminated responders with a sensitivity of 76% (95 % CI 53-92 %) and a specificity of 93 % (95 % CI 66-99 %). Area under the ROC curves for PPVCNAPauto was 0.91 (95 % CI 0.76-0.98), which was not different from that for PPVART. When compared with PPVART, PPVCNAPauto performs satisfactorily in assessing fluid responsiveness in hemodynamically stable surgical patients.

The development and error analysis of a kinematic parameters based spatial positioning method for an orthopedic navigation robot system.

BACKGROUND: Spatial positioning is the key function of a surgical navigation robot system, and accuracy is the most important performance index of such a system. METHODS: The kinematic parameters of a six degrees of freedom (DOF) robot arm were used to form the transformation from intraoperative fluoroscopy images to a robot's coordinate system without C-arm calibration and to solve the redundant DOF problem. The influences of three typical error sources and their combination on the final navigation error were investigated through Monte Carlo simulation. RESULTS: The navigation error of the proposed method is less than 0.6 mm, and the feasibility was verified through cadaver experiments. Error analysis suggests that the robot kinematic error has a linear relationship with final navigation error, while the image error and gauge error have nonlinear influences. CONCLUSIONS: This kinematic parameters based method can provide accurate and convenient navigation for orthopedic surgeries. The result of error analysis will help error design and assignment for surgical robots.

Intraoperative magnetic resonance imaging.

Intraoperative magnetic resonance imaging is a widely accepted method for resection control of glial tumors. Increasingly, it is also used during the resection of skull base tumors. Several studies have independently demonstrated an increase in the extent of resection in these tumors with improved prognosis for the patients. Technical innovations combined with the easier operation of this imaging modality have led to its widespread implementation. The development of digital image processing has also brought other modalities such as ultrasound and computed tomography to the focus of skull base surgery.

Shape Sensing Techniques for Continuum Robots in Minimally Invasive Surgery: A Survey.

Continuum robots provide inherent structural compliance with high dexterity to access the surgical target sites along tortuous anatomical paths under constrained environments and enable to perform complex and delicate operations through small incisions in minimally invasive surgery. These advantages enable their broad applications with minimal trauma and make challenging clinical procedures possible with miniaturized instrumentation and high curvilinear access capabilities. However, their inherent deformable designs make it difficult to realize 3-D intraoperative real-time shape sensing to accurately model their shape. Solutions to this limitation can lead themselves to further develop closely associated techniques of closed-loop control, path planning, human-robot interaction, and surgical manipulation safety concerns in minimally invasive surgery. Although extensive model-based research that relies on kinematics and mechanics has been performed, accurate shape sensing of continuum robots remains challenging, particularly in cases of unknown and dynamic payloads. This survey investigates the recent advances in alternative emerging techniques for 3-D shape sensing in this field and focuses on the following categories: fiber-optic-sensor-based, electromagnetic-tracking-based, and intraoperative imaging modality-based shape-reconstruction methods. The limitations of existing technologies and prospects of new technologies are also discussed.

Assessment of a smartphone app (Capstesia) for measuring pulse pressure variation: agreement between two methods: A Cross-sectional study.

BACKGROUND: Less invasive and noninvasive methods are emerging for haemodynamic monitoring. Among them is Capstesia, a smartphone app that, from photographs of a patient monitor showing invasive arterial pressure, estimates advanced haemodynamic variables after digitising and analysing the pressure curves. OBJECTIVE: The aim of this study was to compare the level of agreement between the analysis of the signals obtained from the patient monitor and a photograph of the same images using the Capstesia app. DESIGN: Cross-sectional study. SETTING: Araba University hospital (Txagorritxu), Vitoria-Gasteiz, Alava, Spain, from January to February 2015. PATIENTS: Twenty patients (229 images) who had an arterial catheter (radial or femoral artery) inserted for haemodynamic monitoring. INTERVENTION: Snapshots obtained from the patient monitor and a photograph of these same snapshots using the Capstesia application were assessed with the same software (MATLAB, Mathworks, Natick, Massachusetats, USA) for evaluating the level of concordance of the following variables: pulse pressure variation (PPV), cardiac output (CO) and maximum slope of the pressure curve (dP/dt). Comparison was made using interclass correlation coefficients with corresponding 95% confidence intervals, and Bland-Altman plots with the corresponding percentages of error. MAIN OUTCOME MEASURES: (PPV). Secondary outcome: CO and maximum slope of the pressure curve [dP/dt]. RESULTS: The interclass correlation coefficients for PPV, CO and max dP/dt were 0.991 (95% confidence interval 0.988 to 0.993), 0.966 (95% confidence interval 0.956 to 0.974) and 0.962 (95% confidence interval 0.950 to 0.970), respectively. In the Bland-Altman analysis, bias and limits of agreement of PPV were (0.50% ±â€Š1.42) resulting in a percentage of error of 20% for PPV. For CO they were 0.19 ±â€Š0.341, with a 13.8% of error. Finally bias and limits of agreement for max dP/dt were 1.33 ±â€Š77.71, resulting in an error of 14.20% CONCLUSIONS: Photograph of the screenshots obtained with the Capstesia app show a good concordance with analysis of the original screenshots. Either approach could be used to monitor the haemodynamic variables assessed.

Use of a patient completed iPad questionnaire to improve pre-operative assessment.

Developments in healthcare technology could improve patient care and reduce healthcare costs. There is a need to facilitate communication and increase efficiency in surgical pre-assessment clinics. This study aimed to develop an iPad application to deliver an electronic patient questionnaire, and to evaluate its use in the pre-assessment environment. Software was developed, MyOp, for a standard iPad that mirrored the paper-based pre-assessment system, with features designed for ease of patient use and remote data transfer. A case-control study was conducted, comparing use of MyOp with paper-based practice, to evaluate feasibility and patient preference. Patients were offered the use of MyOp or paper-based system. Outcomes measured included time to complete iPad questionnaire, consultation duration, and a patient preference questionnaire. MyOp cost £3500 to develop. 104 individuals participated in the study, 53 MyOp and 51 controls. MyOp reduced the median consultation duration by 5.00 min. A reduction was seen in all subgroups except those aged over 70 or urology patients. Patients preferred to complete the form independently, using a touchpad or computer but expressed concerns about data security. Use of an electronic patient questionnaire reduces consultation time delivering greater efficiency of pre-assessment nurse time. Preconceived ideas about the use of technology in older age groups are likely inaccurate and less of a barrier than previously thought. Electronic pre-assessments could be used routinely to reduce demands on healthcare facilities, improve patient care, and triage patients prior to clinic attendance.