A Multifaceted Extubation Protocol to Reduce Reintubation Rates in the Surgical ICU.

BACKGROUND: Reintubation is associated with significant morbidity and mortality. The reintubation rate in surgical ICUs (SICUs) is ∼10% nationally but was 17.0% in our SICU. The objective of this study was to determine if the reintubation rate could be reduced with a protocol for extubation assessment and post-extubation care consisting of standardized extubation criteria and targeted interventions for patients at high risk for reintubation. METHODS: Standardized extubation criteria for all SICU patients were identified via literature review and best-practice guidelines. High reintubation risk criteria were identified (age ≥ 65 years, chronic cardiopulmonary disease, ≥ 4 days intubated, emergency intubation, and fluid balance ≥ 5 liters) through a literature review and 13-month retrospective review of reintubations in our institution's SICU. Patients meeting at least one criterion putting them at higher risk for reintubation received interventions including post-extubation high-flow nasal cannula for 24 hours and algorithm-guided respiratory therapy. RESULTS: During the 12-month period following protocol implementation, 36 of 402 extubations resulted in reintubations (9.0% vs. 17.0% preintervention, p < 0.001). Among all extubations, 305 (75.9%) were identified as high risk. Among reintubated patients, 34 (94.4%) met high-risk criteria. The mortality rate for reintubated patients was 40.0%, compared to 3.3% in those not reintubated (p < 0.001). The high-risk screening tool had a negative predictive value of 98%. CONCLUSION: A multifaceted and pragmatic extubation and post-extubation care protocol significantly reduced one SICU's reintubation rate. This protocol can be easily implemented in any SICU to improve patient outcomes following extubation.

Discordances Between Factors Associated With Withholding Extubation and Extubation Failure After a Successful Spontaneous Breathing Trial.

OBJECTIVES: To identify whether factors associated with withholding extubation in the ICU also predict the risk of extubation failure. DESIGN: Retrospective cohort study. SETTING: Eight medical-surgical ICUs in Toronto. PATIENTS: Adult patients receiving invasive mechanical ventilation, with a first successful spontaneous breathing trial within 28 days of initial ICU admission. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary end point had three mutually exclusive levels, including: 1) withholding extubation after a successful spontaneous breathing trial, 2) extubation failure within 48 hours, and 3) successful extubation. Among 9,910 patients, 38% of patients were not extubated within 24 hours of their first successful spontaneous breathing trial. A total of 12.9% of patients who were promptly extubated failed within the next 48 hours. Several discrepancies were evident in the association of factors with risk of withholding extubation and extubation failure. Specifically, both age and female sex were associated with withholding extubation (odds ratio, 1.07; 95% CI, 1.03-1.11; and odds ratio, 1.13; 95% CI, 1.02-1.26, respectively) but not a higher risk of failed extubation (odds ratio, 0.99; 95% CI, 0.93-1.05; and odds ratio, 0.93; 95% CI, 0.77-1.11, respectively). Conversely, both acute cardiovascular conditions and intubation for hypoxemic respiratory failure were associated with a higher risk of failed extubation (odds ratio, 1.32; 95% CI, 1.06-1.66; and odds ratio, 1.46; 95% CI, 1.16-1.82, respectively) but not a higher odds of a withheld extubation attempt (odds ratio, 0.79; 95% CI, 0.68-0.91; and odds ratio, 1.07; 95% CI, 0.93-1.23, respectively). CONCLUSIONS: Several factors showed discordance between the decision to withhold extubation and the risk of extubation failure. This discordance may lead to longer duration of mechanical ventilation or higher reintubation rates. Improving the decision-making behind extubation may help to reduce both exposure to invasive mechanical ventilation and extubation failure.

A quantitative evaluation of aerosol generation during supraglottic airway insertion and removal.

Many guidelines consider supraglottic airway use to be an aerosol-generating procedure. This status requires increased levels of personal protective equipment, fallow time between cases and results in reduced operating theatre efficiency. Aerosol generation has never been quantitated during supraglottic airway use. To address this evidence gap, we conducted real-time aerosol monitoring (0.3-10-µm diameter) in ultraclean operating theatres during supraglottic airway insertion and removal. This showed very low background particle concentrations (median (IQR [range]) 1.6 (0-3.1 [0-4.0]) particles.l-1 ) against which the patient's tidal breathing produced a higher concentration of aerosol (4.0 (1.3-11.0 [0-44]) particles.l-1 , p = 0.048). The average aerosol concentration detected during supraglottic airway insertion (1.3 (1.0-4.2 [0-6.2]) particles.l-1 , n = 11), and removal (2.1 (0-17.5 [0-26.2]) particles.l-1 , n = 12) was no different to tidal breathing (p = 0.31 and p = 0.84, respectively). Comparison of supraglottic airway insertion and removal with a volitional cough (104 (66-169 [33-326]), n = 27), demonstrated that supraglottic airway insertion/removal sequences produced <4% of the aerosol compared with a single cough (p < 0.001). A transient aerosol increase was recorded during one complicated supraglottic airway insertion (which initially failed to provide a patent airway). Detailed analysis of this event showed an atypical particle size distribution and we subsequently identified multiple sources of non-respiratory aerosols that may be produced during airway management and can be considered as artefacts. These findings demonstrate supraglottic airway insertion/removal generates no more bio-aerosol than breathing and far less than a cough. This should inform the design of infection prevention strategies for anaesthetists and operating theatre staff caring for patients managed with supraglottic airways.

Difficult Airway Management in Adult Coronavirus Disease 2019 Patients: Statement by the Society of Airway Management.

The coronavirus disease 2019 (COVID-19) disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), often results in severe hypoxemia requiring airway management. Because SARS-CoV-2 virus is spread via respiratory droplets, bag-mask ventilation, intubation, and extubation may place health care workers (HCW) at risk. While existing recommendations address airway management in patients with COVID-19, no guidance exists specifically for difficult airway management. Some strategies normally recommended for difficult airway management may not be ideal in the setting of COVID-19 infection. To address this issue, the Society for Airway Management (SAM) created a task force to review existing literature and current practice guidelines for difficult airway management by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. The SAM task force created recommendations for the management of known or suspected difficult airway in the setting of known or suspected COVID-19 infection. The goal of the task force was to optimize successful airway management while minimizing exposure risk. Each member conducted a literature review on specific clinical practice section utilizing standard search engines (PubMed, Ovid, Google Scholar). Existing recommendations and evidence for difficult airway management in the COVID-19 context were developed. Each specific recommendation was discussed among task force members and modified until unanimously approved by all task force members. Elements of Appraisal of Guidelines Research and Evaluation (AGREE) Reporting Checklist for dissemination of clinical practice guidelines were utilized to develop this statement. Airway management in the COVID-19 patient increases HCW exposure risk. Difficult airway management often takes longer and may involve multiple procedures with aerosolization potential, and strict adherence to personal protective equipment (PPE) protocols is mandatory to reduce risk to providers. When a patient's airway risk assessment suggests that awake tracheal intubation is an appropriate choice of technique, and procedures that may cause increased aerosolization of secretions should be avoided. Optimal preoxygenation before induction with a tight seal facemask may be performed to reduce the risk of hypoxemia. Unless the patient is experiencing oxygen desaturation, positive pressure bag-mask ventilation after induction may be avoided to reduce aerosolization. For optimal intubating conditions, patients should be anesthetized with full muscle relaxation. Videolaryngoscopy is recommended as a first-line strategy for airway management. If emergent invasive airway access is indicated, then we recommend a surgical technique such as scalpel-bougie-tube, rather than an aerosolizing generating procedure, such as transtracheal jet ventilation. This statement represents recommendations by the SAM task force for the difficult airway management of adults with COVID-19 with the goal to optimize successful airway management while minimizing the risk of clinician exposure.

Evaluation of the Perceived Barriers and Facilitators to Timely Extubation of Critically Ill Adults: An Interprofessional Survey.

BACKGROUND: Spontaneous breathing trials (SBTs) are an evidence-based way of identifying patients ready for mechanical ventilation (MV) liberation. Despite their effectiveness, global SBT performance rates remain suboptimal, and many patients who demonstrate the ability to breathe on their own remain on MV. The factors that influence clinicians' decision to discontinue MV following a successful SBT remain unclear. AIMS: The aim of this study was to explore the underlying causes of extubation delays in the intensive care unit (ICU) from an interprofessional perspective. METHODS: An exploratory, descriptive, cross-sectional design was used. An online survey was administered in December 2019 to clinicians practicing in three ICUs at a single medical center in the U.S. Survey questions focused on clinicians' perceptions of current MV liberation practices and perceived barriers or facilitators to timely extubation after a successful SBT. RESULTS: Of 425 eligible clinicians, 135 completed the survey (31.7% response rate). The majority of clinicians believed the current SBT and extubation process took too long (n = 108; 80.0%) and that this delay negatively affected patient outcomes. While professional groups differed in their rankings of importance, factors perceived to contribute to extubation delays most commonly included SBT timing, low provider confidence levels in making extubation decisions, and patient-specific factors. Potential strategies to overcome these barriers included developing an automated extubation protocol, performing SBTs when the provider responsible for final extubation decisions is physically present, and decreasing clinician perception of reprimand or condemnation for failed extubations. LINKING EVIDENCE TO ACTION: The MV liberation process is complex and dependent on the decisions of various ICU professionals. Clinicians perceive a number of potentially modifiable provider- and organizational-level factors that cause extubation delays in everyday practice. Understanding and addressing these barriers is essential for improving ICU quality and patient outcomes. Future research should explore the effect of nurse and respiratory therapist-driven extubation protocols on MV liberation rates.

Comparison of Percentage Prolonged Times to Tracheal Extubation Between a Japanese Teaching Hospital and One in the United States, Without and With a Phase I Postanesthesia Care Unit.

BACKGROUND: Prolonged times to tracheal extubation are those from end of surgery (dressing on the patient) to extubation 15 minutes or longer. They are so long that others in the operating room (OR) generally have exhausted whatever activities can be done. They cause delays in the starts of surgeons' to-follow cases and are associated with longer duration workdays. Anesthesiologists rate them as being inferior quality. We compare prolonged times to extubation between a teaching hospital in the United States with a phase I postanesthesia care unit (PACU) and a teaching hospital in Japan without a PACU. Our report is especially important during the coronavirus disease 2019 (COVID-19) pandemic. Anesthesiologists with some patients undergoing general anesthetics and having initial PACU recovery in the ORs where they had surgery can learn from the Japanese anesthesiologists with all patients recovering in ORs. METHODS: The historical cohort study included all patients undergoing gynecological surgery at a US hospital (N = 785) or Japanese hospital (N = 699), with the time from OR entrance to end of surgery of at least 4 hours. RESULTS: The mean times from end of surgery to OR exit were slightly longer at the US hospital than at the Japanese hospital (mean difference 1.9 minutes, P < .0001). The mean from end of surgery to discharge to surgical ward at the US hospital also was longer (P < .0001), mean difference 2.2 hours. The sample standard deviations of times from end of surgery until tracheal extubation was 40 minutes for the US hospital versus 4 minutes at the Japanese hospital (P < .0001). Prolonged times to tracheal extubation were 39% of cases at the US hospital versus 6% at the Japanese hospital; relative risk 6.40, 99% confidence interval (CI), 4.28-9.56. Neither patient demographics, case characteristics, surgeon, anesthesiologist, nor anesthesia provider significantly revised the risk ratio. There were 39% of times to extubation that were prolonged among the patients receiving neither remifentanil nor desflurane (all such patients at the US hospital) versus 6% among the patients receiving both remifentanil and desflurane (all at the Japanese hospital). The relative risk 7.12 (99% CI, 4.59-11.05) was similar to that for the hospital groups. CONCLUSIONS: Differences in anesthetic practice can facilitate major differences in patient recovery soon after anesthesia, useful when the patient will recover initially in the OR or if the phase I PACU is expected to be unable to admit the patient.

Preventive use of respiratory support after scheduled extubation in critically ill medical patients-a network meta-analysis of randomized controlled trials.

BACKGROUND: Respiratory support has been increasingly used after extubation for the prevention of re-intubation and improvement of prognosis in critically ill medical patients. However, the optimal respiratory support method is still under debate. This network meta-analysis (NMA) aims to evaluate the comparative effectiveness of various respiratory support methods used for preventive purposes after scheduled extubation in critically ill medical patients. METHODS: A systematic database search was performed from inception to December 19, 2019, for randomized controlled trials (RCTs) that compared a preventive use of different respiratory support methods, including conventional oxygen therapy (COT), noninvasive ventilation (NIV), high-flow oxygen therapy (HFOT), and combinational use of HFOT and NIV (HFOT+NIV), after planned extubation in adult critically ill medical patients. Study selection, data extraction, and quality assessments were performed in duplicate. The primary outcomes included re-intubation rate and short-term mortality. RESULTS: Seventeen RCTs comprising 3341 participants with 4 comparisons were included. Compared with COT, NIV significantly reduced the re-intubation rate [risk ratio (RR) 0.55, 95% confidence interval (CI) 0.39 to 0.77; moderate quality of evidence] and short-term mortality (RR 0.66, 95% CI 0.48 to 0.91; moderate quality of evidence). Compared to COT, HFOT had a beneficial effect on the re-intubation rate (RR 0.55, 95% CI 0.35 to 0.86; moderate quality of evidence) but no effect on short-term mortality (RR 0.79, 95% CI 0.56 to 1.12; low quality of evidence). No significant difference in the re-intubation rate or short-term mortality was found among NIV, HFOT, and HFOT+NIV. The treatment rankings based on the surface under the cumulative ranking curve (SUCRA) from best to worst for re-intubation rate were HFOT+NIV (95.1%), NIV (53.4%), HFOT (51.2%), and COT (0.3%), and the rankings for short-term mortality were NIV (91.0%), HFOT (54.3%), HFOT+NIV (43.7%), and COT (11.1%). Sensitivity analyses of trials with a high risk of extubation failure for the primary outcomes indicated that the SUCRA rankings were comparable to those of the primary analysis. CONCLUSIONS: After scheduled extubation, the preventive use of NIV is probably the most effective respiratory support method for comprehensively preventing re-intubation and short-term death in critically ill medical patients, especially those with a high risk of extubation failure.

Airway Management in the Operating Room and Interventional Suites in Known or Suspected COVID-19 Adult Patients: A Practical Review.

Current evidence suggests that coronavirus disease 2019 (COVID-19) spread occurs via respiratory droplets (particles >5 µm) and possibly through aerosol. The rate of transmission remains high during airway management. This was evident during the 2003 severe acute respiratory syndrome epidemic where those who were involved in tracheal intubation had a higher risk of infection than those who were not involved (odds ratio 6.6). We describe specific airway management principles for patients with known or suspected COVID-19 disease for an array of critical care and procedural settings. We conducted a thorough search of the available literature of airway management of COVID-19 across a variety of international settings. In addition, we have analyzed various medical professional body recommendations for common procedural practices such as interventional cardiology, gastroenterology, and pulmonology. A systematic process that aims to protect the operators involved via appropriate personal protective equipment, avoidance of unnecessary patient contact and minimalization of periprocedural aerosol generation are key components to successful airway management. For operating room cases requiring general anesthesia or complex interventional procedures, tracheal intubation should be the preferred option. For interventional procedures, when tracheal intubation is not indicated, cautious conscious sedation appears to be a reasonable approach. Awake intubation should be avoided unless it is absolutely necessary. Extubation is a high-risk procedure for aerosol and droplet spread and needs thorough planning and preparation. As updates and modifications in the management of COVID-19 are still evolving, local guidelines, appraised at regular intervals, are vital in optimizing clinical management.

Compliance With Evidence-Based Processes of Care After Transitions Between Staff Intensivists.

OBJECTIVES: We sought to evaluate the impact of transitions of care among staff intensivists on the compliance with evidence-based processes of care. DESIGN: Cohort study using data from the Toronto Intensive Care Observational Registry. SETTING: Seven academic ICUs in Toronto, Ontario. PATIENTS: Critically ill mechanically ventilated adult patients. INTERVENTIONS: We explored the effects of the weekly transition of care among staff intensivists on compliance with three evidence-based processes of care (spontaneous breathing trials, lung-protective ventilation, and neuromuscular blocking agents). Two practices that are less guided by evidence (early discontinuation of antibiotics and extubation attempts) served as positive controls. We conducted the analysis using generalized estimating equations to account for clustering at the patient level. MEASUREMENTS AND MAIN RESULTS: The cohort consisted of 10,570 patients admitted between June 2014 and August 2018. Compliance varied for each practice (63.6%, 42.5%, and 21.1% for lung-protective ventilation, spontaneous breathing trials, and neuromuscular blockade, respectively). There was no effect of transitions of care on compliance with spontaneous breathing trials (odds ratio, 1.00; 95% CI, 0.95-1.07), lung-protective ventilation (odds ratio, 1.07, 95% CI, 0.90-1.26), or neuromuscular blockade use (odds ratio, 0.95; 95% CI, 0.75-1.20). However, early antibiotic discontinuation was more likely (odds ratio, 1.23; 95% CI, 1.06-1.42) and extubation attempts were less frequent (odds ratio, 0.77; 95% CI, 0.65-0.93) after a transition of care. CONCLUSIONS: We observed no significant impact of transitions of care between individual staff physicians on evidence-based processes of care for mechanically ventilated adult patients. However, transitions were associated with a lower likelihood of extubation and higher odds of earlier discontinuation of antibiotics.

Speech and Safety in Tracheostomy Patients Receiving Mechanical Ventilation: A Systematic Review.

OBJECTIVE: To synthesize evidence of the safety and effectiveness of phonation in patients with fenestrated tracheostomy tubes. METHODS: PubMed, CINAHL, Scopus, Cochrane, and Web of Science databases were searched. The research question was, "Are fenestrated tracheostomy tubes a safe and effective option to facilitate early phonation in patients undergoing tracheostomy?" Studies of fenestrated tracheostomy tubes were assessed for risk of bias and quality of evidence. Data were abstracted, cross-checked for accuracy, and synthesized. RESULTS: Of the 160 studies identified, 13 met inclusion criteria, including 6 clinical studies (104 patients), 6 case reports (13 patients), and 1 nationwide clinician survey. The primary indications for a tracheostomy were chronic ventilator dependence (83%) and airway protection (17%). Indications for fenestrated tracheostomy included inaudible phonation and poor voice intelligibility. Patients with fenestrated tubes achieved robust voice outcomes. Complications included granulation tissue (6 patients [5%]), malpositioning (1 patient [0.9%]), decreased oxygen saturation (3 patients [2.6%]), increased blood pressure (1 patient [0.9%]), increased peak pressures (2 patients [1.7%]), and air leakage (1 patient [0.9%]); subcutaneous emphysema also occurred frequently. Patient-reported symptoms included shortness of breath (4 patients [3.4%]), anxiety (3 patients [2.6%]), and chest discomfort (1 patient [0.9%]). CONCLUSIONS: Fenestrated devices afford benefits for speech and decannulation but carry risks of granulation, aberrant airflow, and acclimation challenges. Findings highlight the need for continued innovation, education, and quality improvement around the use of fenestrated devices.

Improvement in Successful Extubation in Newborns After a Protocol-driven Approach: A Quality Improvement Initiative.

OBJECTIVE: To reduce extubation failure rate by implementing protocol-driven ventilation and extubation strategies. METHODS: Quality improvement project in a level II neonatal care unit from April 2017 to January 2018. Ventilation and extubation protocols implemented from 1 August, 2017. 18 ventilated newborns in the pre-protocol period, 16 in Plan-do-check-act (PDCA) cycle I and 17 in PDCA cycle II. Primary outcome was extubation failure within the first 72 h of extubation. RESULTS: Extubation failure rate reduced from 41.7% (pre-protocol period) to 23.8% (PDCA 1 and 2, OR 0.44, 95% CI 0.12 to 1.59, P = 0.21). Median time to first extubation attempt significantly decreased (71.5 h to 38 h, P=0.046). CONCLUSIONS: A protocolized approach through quality improvement initiative demonstrated a sustained improvement in successful extubation with a significant reduction in the median time to first extubation attempt in ventilated newborns.

Tracheostomy decannulation methods and procedures for assessing readiness for decannulation in adults: a systematic scoping review.

Despite the undisputable benefits of tracheostomy, it has been reported to have links with impaired communication, reduced quality of life and a risk of health complications such as bleeding, tracheal stenosis and in some cases resulting in mortality. There is a paucity of literature on tracheostomy decannulation methods and procedures, leaving the decision to expert opinion and institutional guidelines. This study aimed to map evidence on methods and procedures of tracheostomy decannulation in adults and assessment of readiness for decannulation, to reveal knowledge gaps and inform further research. We conducted a systematic search of peer reviewed and grey literature on PubMed/MEDLINE, Google Scholar, Union Catalogue of Theses and Dissertations via SABINET Online, World Cat Dissertations and Theses via OCLC, WHO library and governmental websites from 1985 to present. Following title screening, abstract and full article screening was performed by two independent reviewers guided by the eligibility criteria. Data from included studies were extracted, collated, summarized and synthesized into the following themes: assessment, removal, monitoring and definition of failure of decannulation. Quality of the included studies was assessed using the Mixed Methods Appraisal Tool version 2011. Twenty-five out of 51 screened articles were eligible for data extraction. There was wide variation in the assessment methods employed across and within similar patient groups. The common themes that emerged in the assessment for readiness for decannulation are informed consent, clinical stability, airway patency, physiological decannulation, swallowing assessment, level of consciousness, effectiveness of cough and clearance of secretions. In conclusion, the current body of evidence is inadequate and requires further research, particularly validation of different parameters used. A protocol approach to decannulation may be inappropriate but rather an algorithmic approach using validated parameters.

Reduction in Unintended Extubations in a Level IV Neonatal Intensive Care Unit.

OBJECTIVES: Unintended extubations (UEs) lead to significant morbidity in neonates. A quality improvement project was initiated in response to high rates in our level IV NICU. We targeted creating and sustaining UE rates below the published standard of 1 per 100 ventilator days. METHODS: This project spanned 4 time periods: baseline, epoch 1 (December 2010-May 2012), sustain, and epoch 2 (May 2015-December 2017) by using standard quality improvement methodology. Epoch 1 interventions included real-time analysis of UE events, standardization of taping, patient positioning and movement, accurate event reporting, and change in nomenclature. Epoch 2 interventions included reduction in daily chest radiographs (CXRs) and development of a high-risk tool. Patient and event characteristics were statistically compared across time points. RESULTS: Of the 612 UE events recorded over 10 years, 249 UEs occurred from May 2011 to 2017 involving 184 unique patients. UE rates decreased by 43% (from 1.75 to 0.99 per 100 ventilator days; epoch 1) and were sustained until a notable spike. Epoch 2 interventions led to a further 31% rate reduction. Single CXR use decreased by half. Median corrected gestational age at the time of an event was 35 weeks (interquartile range: 29-41). Seventy percent of infants experiencing an UE required reintubation, 29% had a previous event, and 9% had a code event. CONCLUSIONS: A decrease in UE below benchmarks can be achieved and sustained by standardization and mitigation interventions. This decline was also accompanied by a reduction in use of CXRs without increasing UE events.

Decreasing failed extubations with the implementation of an extubation checklist.

BACKGROUND: Failed extubation has been shown to increase ICU stay, transfers to rehabilitation facilities, and mortality. The purpose of this study was to assess the differences in rates of failed extubation before and after implementation of an extubation checklist. METHODS: We performed a retrospective study from January 2013-April 2017 on adult trauma patients (age 18-89) who were admitted to the ICU and required mechanical ventilation. Patients were grouped before and after implementation of an extubation checklist and compared. RESULTS: A total of 993 patients were included in this study. After checklist implementation, significantly fewer patients required reintubation compared to those prior to checklist (7% vs 3%, p = 0.005). There was no difference in mortality (20% vs 21%, p = 0.54) or hospital length of stay between the two groups (16 days vs 15 days, p = 0.16). CONCLUSION: Our study reveals that implementing an extubation checklist is associated with fewer failed extubations.

A Neurologic Examination for Anesthesiologists: Assessing Arousal Level during Induction, Maintenance, and Emergence.

Anesthetics have profound effects on the brain and central nervous system. Vital signs, along with the electroencephalogram and electroencephalogram-based indices, are commonly used to assess the brain states of patients receiving general anesthesia and sedation. Important information about the patient's arousal state during general anesthesia can also be obtained through use of the neurologic examination. This article reviews the main components of the neurologic examination focusing primarily on the brainstem examination. It details the components of the brainstem examination that are most relevant for patient management during induction, maintenance, and emergence from general anesthesia. The examination is easy to apply and provides important complementary information about the patient's arousal level that cannot be discerned from vital signs and electroencephalogram measures.