Comparison of preoxygenation with a high-flow nasal cannula and a simple face mask before intubation in Korean patients with head and neck cancer.

BACKGROUND: Although preoxygenation is an essential procedure for safe endotracheal intubation, in some cases securing sufficient time for tracheal intubation may not be possible. Patients with head and neck cancer might have a difficult airway and need a longer time for endotracheal intubation. We hypothesized that the extended apneic period with preoxygenation via a high-flow nasal cannula (HFNC) is beneficial to patients who undergo head and neck surgery compared with preoxygenation with a simple mask. METHODS: The study was conducted as a single-center, single-blinded, prospective, randomized controlled trial. Patients were divided into groups based on one of the two preoxygenation. METHODS: HFNC group or simple facemask (mask group). Preoxygenation was performed for 5 minutes with each method, and endotracheal intubation for all patients was performed using a video laryngoscope. Oxygen partial pressures of the arterial blood were compared at the predefined time points. RESULTS: For the primary outcome, the mean arterial oxygen partial pressure (PaO2 ) immediately after intubation was 454.2 mm Hg (95% confidence interval [CI], 416.9-491.5 mm Hg) in the HFNC group and 370.7 mm Hg (95% CI, 333.7-407.4 mm Hg) in the mask group (P=0.002). The peak PaO2 at 5 minutes after preoxygenation was not statistically different between the groups (P=0.355). CONCLUSIONS: Preoxygenation with a HFNC extending to the apneic period before endotracheal intubation may be beneficial in patients with head and neck cancer.

Arrhythmia incidence and associated factors during volatile induction of general anesthesia with sevoflurane: a retrospective analysis of 950 adult patients.

BACKGROUND: Sevoflurane has been used to induce anaesthesia in adults due to its suitability for airway management and haemodynamic stability. Few studies have reported arrhythmia during volatile induction with sevoflurane in adults. Here, we investigated the incidence of arrhythmia and risk factors associated with its occurrence during sevoflurane induction of anaesthesia in adults. PATIENTS AND METHODS: We retrospectively analysed 950 adult patients who underwent elective ear nose and throat surgery with volatile induction using sevoflurane between May and December 2015. The incidence of arrhythmia and the factors associated with its development were analysed. RESULTS: Arrhythmia was observed in 164 (17.3%) of 950 adult patients. The most frequently observed arrhythmia was sinus tachycardia (heart rate > 120 bpm) (77 patients, 47.0%). The multivariable logistic analysis showed four independent risk factors: age (odds ratio [OR] = 0.984, 95% confidence interval [CI] = 0.973-0.996, p = 0.006), coronary artery disease (OR = 3.749, 95% CI = 1.574-8.927, p = 0.003), maximal concentration (8 vol%) of sevoflurane from the start of induction (OR = 2.696, 95% CI = 1.139-6.382, p = 0.024), and maintenance of 8 vol% sevoflurane concentration after eyelash reflex loss (OR = 1.577, 95% CI = 1.083-2.296, p = 0.018). The risk of hypotension was greater in patients in whom arrhythmia occurred, although blood pressure recovered to baseline after the concentration of sevoflurane was adjusted. CONCLUSIONS: We recommend that the sevoflurane concentration be gradually increased with continuous and vigilant electrocardiogram and blood pressure monitoring. The sevoflurane concentration should be adjusted after sufficient unconsciousness is reached.

Negative pressure pulmonary edema in a patient undergoing open rhinoplasty: A case report.

RATIONALE: Negative pressure pulmonary edema (NPPE) is associated with serious postoperative complications. Compact nasal packing is always done after an open rhinoplasty procedure which makes it difficult to achieve positive pressure ventilation via a mask if NPPE arises. PATIENT CONCERNS: A 21-year-old healthy man got an open rhinoplasty, septal perforation repair, and revisional septal reconstruction. After surgery, he became so agitated that it was difficult to calm him. We decided to remove the endotracheal tube. On arrival at the post-anesthesia care unit, he was cyanotic and his SpO2 had decreased to about 2%. We attempted positive pressure ventilation using mask bagging; however, it was ineffective due to the nasal packing. DIAGNOSES: Negative pressure pulmonary edema. INTERVENTIONS: Emergent reintubation was immediately done and Ambu bagging was commenced. A considerable pinkish secretion came out of the tube. A T-piece was applied to him using 15 L/min of oxygen supply. The patient was eventually transferred to the intensive care unit of our hospital. OUTCOMES: On postoperative day (POD) 1, a decision was made to extubate, and the oxygen supply was shifted to 3L/min using a venturi-mask. On POD 2, a chest posteroanterior radiograph was taken and indicated no active lung lesion. The patient was subsequently discharged without any complications. He had no symptoms on POD 6, 11, and 18 at follow-up visits to our outpatient clinic. LESSONS: Anesthesiologists should be alert to the possibility of NPPE and its treatment because of its rapid onset but positive clinical outcome if there is a proper intervention. In nasal surgery cases in particular, early re-intubation should be conducted and extubation should be done to fully awaken the patients.

Optimization of the Operating Room Scheduling Process for Improving Efficiency in a Tertiary Hospital.

Efficient operating room (OR) scheduling can improve OR utilization and reduce costs. We hypothesize that the scheduling office (ORSO) leading the modification scheduling process could increase OR utilization rate. Using retrospective data from a single tertiary hospital in two consecutive calendar years, we compared OR utilization rate, the number of daily cases and cumulative operative time in the pre- and post-implementation of scheduling process alteration. We operated about 100,609 cases in the OR during the study period. Daytime utilization rate increased from 85.6% to 89.4% (P < 0.001); overall OR utilization rate from 115.1% to 117.6% (P = 0.019); daily case numbers from 229.9 ± 7.3 to 239.6 ± 7.6 (P = 0.0.14); and cumulative operation time of total and daytime cases from 611.7 case-hour/day to 624.5 case-hour/day (P = 0.013) and from 510.8 case-hour/day to 533.8 case-hour/day (P < 0.001), respectively. Evening/night time case-hour significantly decreased from 100.9 case-hour/day to 90.7 case-hour/day (P < 0.001). The optimization of the scheduling process and coordination by the office during regular workhours resulted in enhanced OR efficiency. The OR scheduling office can act as a control tower to make OR management more flexible, which can improve efficiency and carry financial benefits in tertiary hospitals.

Real-Time Monitoring of Blood Pressure Using Digitalized Pulse Arrival Time Calculation Technology for Prompt Detection of Sudden Hypertensive Episodes During Laryngeal Microsurgery: Retrospective Observational Study.

BACKGROUND: Laryngeal microsurgery (LMS) is often accompanied by a sudden increase in blood pressure (BP) during surgery because of stimulation around the larynx. This sudden change in the hemodynamic status is not immediately reflected in a casual cuff-type measurement that takes intermittent readings every 3 to 5 min. OBJECTIVE: This study aimed to investigate the potential of pulse arrival time (PAT) as a marker for a BP surge, which usually occurs in patients undergoing LMS. METHODS: Intermittent measurements of BP and electrocardiogram (ECG) and photoplethysmogram (PPG) signals were recorded during LMS. PAT was defined as the interval between the R-peak on the ECG and the maximum slope on the PPG. Mean PAT values before and after BP increase were compared. PPG-related parameters and the correlations between changes in these variables were calculated. RESULTS: BP surged because of laryngoscopic manipulation (mean systolic BP [SBP] from 115.3, SD 21.4 mmHg, to 159.9, SD 25.2 mmHg; P<.001), whereas PAT decreased significantly (from mean 460.6, SD 51.9 ms, to 405.8, SD 50.1 ms; P<.001) in most of the cases. The change in SBP showed a significant correlation with the inverse of the PAT (r=0.582; P<.001). Receiver-operating characteristic curve analysis indicated that an increase of 11.5% in the inverse of the PAT could detect a 40% increase in SBP, and the area under the curve was 0.814. CONCLUSIONS: During LMS, where invasive arterial catheterization is not always possible, PAT shows good correlation with SBP and may, therefore, have the potential to identify abrupt BP surges during laryngoscopic manipulations in a noninvasive manner.

Comparison of preoxygenation with a high-flow nasal cannula and a simple mask before intubation during induction of general anesthesia in patients undergoing head and neck surgery: Study protocol clinical trial (SPIRIT Compliant).

BACKGROUND: To assess the arterial oxygen partial pressure (PaO2) at defined time points during preoxygenation and to compare high-flow heated humidified nasal oxygenation with standard preoxygenation using oxygen insufflation via a facemask for at least 5 minutes, before intubation during induction of general anesthesia. METHODS: This randomized, single-blinded, prospective study will be conducted in patients undergoing head and neck surgery. After standard monitoring, the artery catheter at the radial artery or dorsalis pedis artery will be placed and arterial blood gas analysis (ABGA) for baseline values will be performed simultaneously. Each group will be subjected to 1 of 2 preoxygenation methods (high-flow nasal cannula or simple facemask) for 5 minutes, and ABGA will be performed twice. After confirming intubation, we will start mechanical ventilation and check the vital signs and perform the final ABGA. DISCUSSION: This trial aims to examine the trajectory of PaO2 levels during the whole preoxygenation procedure and after intubation. We hypothesize that preoxygenation with the high-flow nasal cannula will be superior to that with the face mask. STUDY REGISTRATION: This trial was registered with the Clinical Trial Registry (NCT03896906; ClinicalTrials.gov).

Effect of Total Intravenous Anesthesia vs Volatile Induction With Maintenance Anesthesia on Emergence Agitation After Nasal Surgery: A Randomized Clinical Trial.

Importance: Emergence agitation is common after nasal surgery under general anesthesia and may lead to serious consequences for the patient, including an increased risk of injury, pain, hemorrhage, and self-extubation. Despite decades of research, studies on the incidence, risk factors, and prevention of emergence agitation in adult patients are ongoing, and opinions differ on the different effects of inhalation and intravenous anesthesia. Objective: To investigate the effect of anesthetic method on the occurrence of emergence agitation after nasal surgery. Design, Setting, and Participants: This prospective, randomized, single-blind, clinical trial included 80 patients undergoing open rhinoplasty, septoplasty, turbinoplasty, endoscopic sinus surgery, and functional endoscopic sinus surgery under general anesthesia who were randomized to receive total intravenous anesthesia (TIVA) with remifentanil hydrochloride and propofol (n = 40) or volatile induction and maintenance of anesthesia (VIMA) with sevoflurane and nitrous oxide (n = 40) in Asan Medical Center, a tertiary referral center in Seoul, Republic of Korea. Data were collected from August 24 through October 14, 2016, and analyzed from October 26, 2016, through September 14, 2017. Main Outcomes and Measures: The occurrence of emergence agitation defined by the following 2 individual criteria: a Richmond Agitation-Sedation Scale score of at least 1 and a Riker Sedation-Agitation Scale score of at least 5 immediately after extubation. Results: Among the 80 patients included in the analysis (68.8% men [n = 55]; mean [SD] age, 41.6 [17.9] years), emergence agitation measured by the Richmond Agitation Sedation Scale occurred in 8 of 40 patients (20.0%) in the VIMA group and 1 of 40 (2.5%) in the TIVA group. The risk difference was 17.5 (95% CI, 3.6-31.4). Emergence agitation measured by the Riker Sedation-Agitation Scale score occurred in 10 of 40 patients (25.0%) in the VIMA group and 1 of 40 (2.5%) in the TIVA group. The risk difference was 22.5 (95% CI, 7.3-37.7). Conclusions and Relevance: The occurrence of emergence agitation after nasal surgery under general anesthesia can be significantly reduced by using TIVA rather than VIMA. Trial Registration: CRIS identifier: KCT0002145.

Recurrent ST segment elevations in a patient with asymptomatic early repolarization during head and neck surgery: implications of vasospastic angina.

A 57-year-old woman scheduled for cochlear implant removal exhibited preoperative electrocardiographic findings of early repolarization (ER). Four episodes of transient ST segment elevations during surgery raised suspicion for vasospastic angina (VA). In the post-anesthetic care unit, the patient complained of chest discomfort and received sublingual nitroglycerin with uncertain effect. The patient refused to proceed with postoperative invasive coronary angiography, resulting in inconclusive diagnosis. Intraoperative circumstances limit the diagnosis of VA, which emphasizes the need for further testing to confirm the diagnosis. When VA is suspected in patients with underlying ER, it is reasonable to consider invasive examination to establish the diagnosis and prevent recurrence of VA. If ST changes are observed during surgery in patients with preoperative ER, careful monitoring is recommended. Due to general anesthesia, the absence of patient symptoms limits the definitive diagnosis of those with suspected VA. Therefore, additional postoperative surveillance is recommended.

Pulmonary aspiration during intubation in a high-risk patient: A video clip and clinical implications.

We report a case of pulmonary aspiration during induction of general anesthesia in a patient who was status post esophagectomy. Sudden, unexpected aspiration occurred even though the patient had fasted adequately (over 13 hours) and received rapid sequence anesthesia induction. Since during esophagectomy, the lower esophageal sphincter is excised, stomach vagal innervation is lost, and the stomach is flaccid, draining only by gravity, the patient becomes vulnerable to aspiration. As the incidence of perioperative pulmonary aspiration is relatively low, precautions to prevent aspiration tend to be overlooked. We present a video clip showing pulmonary aspiration and discuss the literature concerning the risk of aspiration and its preventive strategies.

Suppressed neural complexity during ketamine- and propofol-induced unconsciousness.

Ketamine and propofol have distinctively different molecular mechanisms of action and neurophysiological features, although both induce loss of consciousness. Therefore, identifying a common feature of ketamine- and propofol-induced unconsciousness would provide insight into the underlying mechanism of losing consciousness. In this study we search for a common feature by applying the concept of type-II complexity, and argue that neural complexity is essential for a brain to maintain consciousness. To test this hypothesis, we show that complexity is suppressed during loss of consciousness induced by ketamine or propofol. We analyzed the randomness (type-I complexity) and complexity (type-II complexity) of electroencephalogram (EEG) signals before and after bolus injection of ketamine or propofol. For the analysis, we use Mean Information Gain (MIG) and Fluctuation Complexity (FC), which are information-theory-based measures that quantify disorder and complexity of dynamics respectively. Both ketamine and propofol reduced the complexity of the EEG signal, but ketamine increased the randomness of the signal and propofol decreased it. The finding supports our claim and suggests EEG complexity as a candidate for a consciousness indicator.

Differential Postoperative Effects of Volatile Anesthesia and Intraoperative Remifentanil Infusion in 7511 Thyroidectomy Patients: A Propensity Score Matching Analysis.

Although remifentanil is used widely by many clinicians during general anesthesia, there are recent evidences of opioid-induced hyperalgesia as an adverse effect. This study aimed to determine if intraoperative remifentanil infusion caused increased pain during the postoperative period in patients who underwent a thyroidectomy. A total of 7511 patients aged ≥ 20 years, who underwent thyroidectomy between January 2009 and December 2013 at the Asan Medical Center were retrospectively analyzed. Enrolled patients were divided into 2 groups: group N (no intraoperative remifentanil and only volatile maintenance anesthesia) and group R (intraoperative remifentanil infusion including total intravenous anesthesia and balanced anesthesia). Following propensity score matching analysis, 2582 patients were included in each group. Pain scores based on numeric rating scales (NRS) were compared between the 2 groups at the postoperative anesthetic care unit and at the ward until 3 days postoperation. Incidences of postoperative complications, such as nausea, itching, and shivering were also compared. The estimated NRS pain score on the day of surgery was 5.08 (95% confidence interval [CI] 4.97-5.19) in group N patients and 6.73 (95% CI 6.65-6.80) in group R patients (P < 0.001). There were no statistically significant differences in NRS scores on postoperative days 1, 2, and 3 between the 2 groups. Postoperative nausea was less frequent in group R (31.4%) than in group N (53.5%) (P < 0.001). However, the incidence of itching was higher in group R (4.3%) than in group N (0.7%) (P < 0.001). Continuous infusion of remifentanil during general anesthesia can cause higher intensity of postoperative pain and more frequent itching than general anesthesia without remifentanil infusion immediately after thyroidectomy. Considering the advantages and disadvantages of continuous remifentanil infusion, volatile anesthesia without opioid may be a good choice for minor surgeries, such as thyroidectomy.

Electroencephalographic effects of ketamine on power, cross-frequency coupling, and connectivity in the alpha bandwidth.

Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at γ-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine (a primarily non-GABAergic anesthetic drug) on alpha oscillations has not been systematically evaluated. We analyzed the electroencephalogram of 28 surgical patients during consciousness and ketamine-induced unconsciousness with a focus on frontal power, frontal cross-frequency coupling, frontal-parietal functional connectivity (measured by coherence and phase lag index), and frontal-to-parietal directional connectivity (measured by directed phase lag index) in the alpha bandwidth. Unlike past studies of propofol, ketamine-induced unconsciousness was not associated with increases in the power of frontal alpha rhythms, characteristic cross-frequency coupling patterns of frontal alpha power and slow-oscillation phase, or decreases in coherence in the alpha bandwidth. Like past studies of propofol using undirected and directed phase lag index, ketamine reduced frontal-parietal (functional) and frontal-to-parietal (directional) connectivity in the alpha bandwidth. These results suggest that directional connectivity changes in the alpha bandwidth may be state-related markers of unconsciousness induced by both GABAergic and non-GABAergic anesthetics.

Subgraph "backbone" analysis of dynamic brain networks during consciousness and anesthesia.

General anesthesia significantly alters brain network connectivity. Graph-theoretical analysis has been used extensively to study static brain networks but may be limited in the study of rapidly changing brain connectivity during induction of or recovery from general anesthesia. Here we introduce a novel method to study the temporal evolution of network modules in the brain. We recorded multichannel electroencephalograms (EEG) from 18 surgical patients who underwent general anesthesia with either propofol (n = 9) or sevoflurane (n = 9). Time series data were used to reconstruct networks; each electroencephalographic channel was defined as a node and correlated activity between the channels was defined as a link. We analyzed the frequency of subgraphs in the network with a defined number of links; subgraphs with a high probability of occurrence were deemed network "backbones." We analyzed the behavior of network backbones across consciousness, anesthetic induction, anesthetic maintenance, and two points of recovery. Constitutive, variable and state-specific backbones were identified across anesthetic state transitions. Brain networks derived from neurophysiologic data can be deconstructed into network backbones that change rapidly across states of consciousness. This technique enabled a granular description of network evolution over time. The concept of network backbones may facilitate graph-theoretical analysis of dynamically changing networks.

Disruption of frontal-parietal communication by ketamine, propofol, and sevoflurane.

INTRODUCTION: Directional connectivity from anterior to posterior brain regions (or "feedback" connectivity) has been shown to be inhibited by propofol and sevoflurane. In this study the authors tested the hypothesis that ketamine would also inhibit cortical feedback connectivity in frontoparietal networks. METHODS: Surgical patients (n = 30) were recruited for induction of anesthesia with intravenous ketamine (2 mg/kg); electroencephalography of the frontal and parietal regions was acquired. The authors used normalized symbolic transfer entropy, a computational method based on information theory, to measure directional connectivity across frontal and parietal regions. Statistical analysis of transfer entropy measures was performed with the permutation test and the time-shift test to exclude false-positive connectivity. For comparison, the authors used normalized symbolic transfer entropy to reanalyze electroencephalographic data gathered from surgical patients receiving either propofol (n = 9) or sevoflurane (n = 9) for anesthetic induction. RESULTS: Ketamine reduced alpha power and increased gamma power, in contrast to both propofol and sevoflurane. During administration of ketamine, feedback connectivity gradually diminished and was significantly inhibited after loss of consciousness (mean ± SD of baseline and anesthesia: 0.0074 ± 0.003 and 0.0055 ± 0.0027; F(5, 179) = 7.785, P < 0.0001). By contrast, feedforward connectivity was preserved during exposure to ketamine (mean ± SD of baseline and anesthesia: 0.0041 ± 0.0015 and 0.0046 ± 0.0018; F(5, 179) = 2.07; P = 0.072). Like ketamine, propofol and sevoflurane selectively inhibited feedback connectivity after anesthetic induction. CONCLUSIONS: Diverse anesthetics disrupt frontal-parietal communication, despite molecular and neurophysiologic differences. Analysis of directional connectivity in frontal-parietal networks could provide a common metric of general anesthesia and insight into the cognitive neuroscience of anesthetic-induced unconsciousness.

Preferential inhibition of frontal-to-parietal feedback connectivity is a neurophysiologic correlate of general anesthesia in surgical patients.

BACKGROUND: The precise mechanism and optimal measure of anesthetic-induced unconsciousness has yet to be elucidated. Preferential inhibition of feedback connectivity from frontal to parietal brain networks is one potential neurophysiologic correlate, but has only been demonstrated in animals or under limited conditions in healthy volunteers. METHODS AND FINDINGS: We recruited eighteen patients presenting for surgery under general anesthesia; electroencephalography of the frontal and parietal regions was acquired during (i) baseline consciousness, (ii) anesthetic induction with propofol or sevoflurane, (iii) general anesthesia, (iv) recovery of consciousness, and (v) post-recovery states. We used two measures of effective connectivity, evolutional map approach and symbolic transfer entropy, to analyze causal interactions of the frontal and parietal regions. The dominant feedback connectivity of the baseline conscious state was inhibited after anesthetic induction and during general anesthesia, resulting in reduced asymmetry of feedback and feedforward connections in the frontoparietal network. Dominant feedback connectivity returned when patients recovered from anesthesia. Both analytic techniques and both classes of anesthetics demonstrated similar results in this heterogeneous population of surgical patients. CONCLUSIONS: The disruption of dominant feedback connectivity in the frontoparietal network is a common neurophysiologic correlate of general anesthesia across two anesthetic classes and two analytic measures. This study represents a key translational step from the underlying cognitive neuroscience of consciousness to more sophisticated monitoring of anesthetic effects in human surgical patients.