Risk factors of post-anaesthesia care unit delirium in patients undergoing non-cardiac surgery in Singapore

Introduction

Post-anaesthesia care unit (PACU) delirium affects 5%-45% of patients after surgery and is associated with postoperative delirium and increased mortality. Up to 40% of PACU delirium is preventable, but it remains under-recognised due to a lack of awareness of its diagnosis. The nursing delirium screening scale (Nu-DESC) has been validated for diagnosing PACU delirium, but is not routinely used locally. This study aimed to use Nu-DESC to establish the incidence and risk factors of PACU delirium in patients undergoing non-cardiac surgery in the surgical population.

Methods

We conducted an audit of eligible patients undergoing major surgery in three public hospitals in Singapore over 1 week. Patients were assessed for delirium 30-60 min following their arrival in PACU using Nu-DESC, with a total score of ≥2 indicative of delirium.

Results

A total of 478 patients were assessed. The overall incidence rate of PACU delirium was 18/478 (3.8%), and the incidence was 9/146 (6.2%) in patients aged > 65 years. Post-anaesthesia care unit delirium was more common in females, patients with malignancy and those who underwent longer operations. Logistic regression analysis showed that the use of bispectral index (P < 0.001) and the presence of malignancy (P < 0.001) were significantly associated with a higher incidence of PACU delirium.

Conclusion

In this first local study, the incidence of PACU delirium was 3.8%, increasing to 6.2% in those aged > 65 years. Understanding these risk factors will form the basis for which protocols can be established to optimise resource management and prevent long-term morbidities and mortality in PACU delirium.

Expert consensus on difficult airway assessment

Background

Identifying a potentially difficult airway is crucial both in anaesthesia in the operating room (OR) and non-operation room sites. There are no guidelines or expert consensus focused on the assessment of the difficult airway before, so this expert consensus is developed to provide guidance for airway assessment, making this process more standardized and accurate to reduce airway-related complications and improve safety.

Methods

Seven members from the Airway Management Group of the Chinese Society of Anaesthesiology (CSA) met to discuss the first draft and then this was sent to 15 international experts for review, comment, and approval. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) is used to determine the level of evidence and grade the strength of recommendations. The recommendations were revised through a three-round Delphi survey from experts.

Results

This expert consensus provides a comprehensive approach to airway assessment based on the medical history, physical examination, comprehensive scores, imaging, and new developments including transnasal endoscopy, virtual laryngoscopy, and 3D printing. In addition, this consensus also reviews some new technologies currently under development such as prediction from facial images and voice information with the aim of proposing new research directions for the assessment of difficult airway.

Conclusions

This consensus applies to anesthesiologists, critical care, and emergency physicians refining the preoperative airway assessment and preparing an appropriate intubation strategy for patients with a potentially difficult airway.

Anesthetic Considerations for Cataract Surgery in Patients with Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is a chronic neurological degenerative disease affecting the central nervous system, which is responsible for progressive disorders such as slow movements, tremors, rigidity, and cognitive disorders. There are no specific recommendations and guidelines for anesthetic management of patients with PD undergoing ophthalmic procedures. This narrative review aims to summarise the anesthetic considerations in patients with PD presenting for cataract surgery.

Besdata Video Laryngeal Mask (BD-VLM)- a New Vision-Incorporated 3rd Generation Video Laryngeal Mask Airway : Dear editor

Since the recent editorial 2, we were approached to evaluate another video laryngeal mask airway - the Besdata Video Laryngeal Mask (BD-VLM) TM, which has a different design concept, specifications and characteristics (Figure 1) compared to the other two.

Characteristics of Patients with Unrecognized Sleep Apnea Requiring Postoperative Oxygen Therapy

Surgical patients with obstructive sleep apnea (OSA) have increased risk of perioperative complications. The primary objective is to determine the characteristics of surgical patients with unrecognized OSA requiring oxygen therapy for postoperative hypoxemia. The secondary objective is to investigate the characteristics of patients who were responsive to oxygen therapy. This was a post-hoc multicenter study involving patients with cardiovascular risk factors undergoing major non-cardiac surgery. Patients ≥45 years old underwent Type 3 sleep apnea testing and nocturnal oximetry preoperatively. Responders to oxygen therapy were defined as individuals with ≥50% reduction in oxygen desaturation index (ODI) on postoperative night 1 versus preoperative ODI. In total, 624 out of 823 patients with unrecognized OSA required oxygen therapy. These were mostly males, had larger neck circumferences, higher Revised Cardiac Risk Indices, higher STOP-Bang scores, and higher ASA physical status, undergoing intraperitoneal or vascular surgery. Multivariable regression analysis showed that the preoperative longer cumulative time SpO2 < 90% or CT90% (adjusted p = 0.03), and lower average overnight SpO2 (adjusted p < 0.001), were independently associated with patients requiring oxygen therapy. Seventy percent of patients were responders to oxygen therapy with ≥50% ODI reduction. Preoperative ODI (19.0 ± 12.9 vs. 14.1 ± 11.4 events/h, p < 0.001), CT90% (42.3 ± 66.2 vs. 31.1 ± 57.0 min, p = 0.038), and CT80% (7.1 ± 22.6 vs. 3.6 ± 8.7 min, p = 0.007) were significantly higher in the responder than the non-responder. Patients with unrecognized OSA requiring postoperative oxygen therapy were males with larger neck circumferences and higher STOP-Bang scores. Those responding to oxygen therapy were likely to have severe OSA and worse preoperative nocturnal hypoxemia. Preoperative overnight oximetry parameters may help in stratifying patients.

Nocturnal Oxygen Desaturation Index Correlates with Respiratory Depression in Post-Surgical Patients Receiving Opioids - A Post-Hoc Analysis from the Prediction of Opioid-Induced Respiratory Depression in Patients Monitored by Capnography (PRODIGY) Study

Purpose

Postoperative monitoring of respiratory status on general care wards typically consists of intermittent checks of oxyhemoglobin saturation and respiratory rate, allowing substantial unmonitored time for severe opioid induced respiratory depression (RD) to develop unnoticed. Oxygen desaturation index (ODI) can be computed solely by continuous pulse oximetry monitoring. In this post-hoc analysis, we evaluate whether nocturnal ODI correlates with RD.

Patients and Methods

The PRODIGY trial (NCT02811302) was a multinational study conducted where adult patients receiving parenteral opioids on the general care floor were continuously monitored by blinded pulse oximetry and capnography monitoring to detect episodes of RD. An RD episode was defined as: respiratory rate ≤5 breaths/min (bpm) for ≥3 minutes, oxygen saturation (SpO2) ≤85% for ≥3 minutes, end-tidal carbon dioxide (EtCO2) ≤15 or ≥60 mm Hg for ≥3 minutes, apnea episode lasting >30 seconds, or any respiratory opioid-related adverse event. Data were used to calculate nocturnal (00:00 ─ 06:00) ODI4% based on desaturation episodes (4% decrease from mean oxyhemoglobin saturation in the past 120 seconds, lasting ≥10 seconds). Continuous monitoring began after a patient received parenteral opioids, allowing identification of potential RD and ODI4% episodes during opioid therapy. The average number of ODI4% episodes (≥1, ≥5, ≥10, ≥15 episodes/hour) were analyzed. Logistic regression and area under the receiver operating characteristic curve (AUC) were computed.

Results

A final cohort of 1072 (out of 1335) patients had sufficient data, with 76% (N=817/1072) having ≥1 episode of ODI4%. Multivariable logistic regression showed that ODI4% was strongly associated with RD, with greater risk for higher ODI4% scores: ≥5 episodes/hour odds ratio 2.59 (95% CI 1.72-3.89, p<0.0001); ≥10 episodes/hour 3.39 (95% CI 1.80-6.39, p=0.0002); ≥15 episodes/hour 4.71 (95% CI 1.93-11.47, p=0.0006).There was no significant association between ODI4% and respiratory adverse events.

Conclusion

Nocturnal ODI4% was highly correlated with RD among hospitalized patients receiving parenteral opioids. Patients with a high ODI4%, especially with ≥15 episodes/hour, are more likely to experience RD and should be evaluated for the need of closer monitoring after opioid administration.

Incidence and risk factors of delirium in post-anaesthesia care unit

INTRODUCTION

Post-anaesthesia care unit (PACU) delirium is a potentially preventable condition that results in a significant long-term effect. In a multicentre prospective cohort study, we investigate the incidence and risk factors of postoperative delirium in elderly patients undergoing major non-cardiac surgery.

METHODS

Patients were consented and recruited from 4 major hospitals in Singapore. Research ethics approval was obtained. Patients older than 65 years undergoing non-cardiac surgery >2 hours were recruited. Baseline perioperative data were collected. Preoperative baseline cognition was obtained. Patients were assessed in the post-anaesthesia care unit for delirium 30-60 minutes after arrival using the Nursing Delirium Screening Scale (Nu-DESC).

RESULTS

Ninety-eight patients completed the study. Eleven patients (11.2%) had postoperative delirium. Patients who had PACU delirium were older (74.6±3.2 versus 70.6±4.4 years, P=0.005). Univariate analysis showed those who had PACU delirium are more likely to be ASA 3 (63.6% vs 31.0%, P=0.019), had estimated glomerular filtration rate (eGFR) of >60mL/min/1.73m2 (36.4% vs 10.6%, P=0.013), higher HbA1C value (7.8±1.2 vs 6.6±0.9, P=0.011), raised random blood glucose (10.0±5.0mmol/L vs 6.5±2.4mmol/L, P=0.0066), and moderate-severe depression (18.2% vs 1.1%, P=0.033). They are more likely to stay longer in hospital (median 8 days [range 4-18] vs 4 days [range 2-8], P=0.049). Raised random blood glucose is independently associated with increased PACU delirium on multivariate analysis.

Academy of Medicine, Singapore clinical guideline on the use of sedation by non-anaesthesiologists during gastrointestinal endoscopy in the hospital setting

INTRODUCTION

In Singapore, non-anaesthesiologists generally administer sedation during gastrointestinal endoscopy. The drugs used for sedation in hospital endoscopy centres now include propofol in addition to benzodiazepines and opiates. The requirements for peri-procedural monitoring and discharge protocols have also evolved. There is a need to develop an evidence-based clinical guideline on the safe and effective use of sedation by non-anaesthesiologists during gastrointestinal endoscopy in the hospital setting.

METHODS

The Academy of Medicine, Singapore appointed an expert workgroup comprising 18 gastroenterologists, general surgeons and anaesthesiologists to develop guidelines on the use of sedation during gastrointestinal endoscopy. The workgroup formulated clinical questions related to different aspects of endoscopic sedation, conducted a relevant literature search, adopted Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology and developed recommendations by consensus using a modified Delphi process.

RESULTS

The workgroup made 16 recommendations encompassing 7 areas: (1) purpose of sedation, benefits and disadvantages of sedation during gastrointestinal endoscopy; (2) pre-procedural assessment, preparation and consent taking for sedation; (3) Efficacy and safety of drugs used in sedation; (4) the role of anaesthesiologist administered sedation during gastrointestinal endoscopy; (5) performance of sedation; (6) post-sedation care and discharge after sedation; and (7) training in sedation for gastrointestinal endoscopy for non-anaesthesiologists.

CONCLUSION

These recommendations serve to guide clinical practice during sedation for gastrointestinal endoscopy by non-anaesthesiologists in the hospital setting.

Awareness and Perspectives among Asian Anesthesiologists on Postoperative Delirium: A Multinational Survey

Postoperative delirium (POD) is a common perioperative complication. Although POD is preventable in up to 40% of patients, it is frequently overlooked. The objective of the survey is to determine the level of knowledge and clinical practices related to POD among anesthesiologists in different Asian countries. A questionnaire of 22 questions was designed by members of the Asian focus group for the study of POD, and it was sent to anesthesiologists in Singapore, Thailand, and South Korea from 1 April 2019 through 17 September 2019. In total, 531 anesthesiologists (Singapore: 224, Thailand: 124, Korea: 183) responded to the survey. Half the respondents estimated the incidence of POD to be 11–30% and believed that it typically occurs in the first 48 h after surgery. Among eight important postoperative complications, POD was ranked fifth. While 51.4% did not perform any test for POD, only 13.7% monitored the depth of anesthesia in all their patients. However, 83.8% preferred depth of anesthesia monitoring if they underwent surgery themselves. The results suggest that Asian anesthesiologists underestimate the incidence and relevance of POD. Because it increases perioperative mortality and morbidity, there is an urgent need to educate anesthesiologists regarding the recognition, prevention, detection, and management of POD.

Comparing the first-attempt tracheal intubation success of the hyperangulated McGrath® X-blade vs the Macintosh-type CMAC videolaryngoscope in patients with cervical immobilization: a two-centre randomized controlled trial

We compared the hyperangulated McGrath X-blade with the Macintosh-type CMAC videolaryngoscope through the use of manual in-line stabilization on patients. The primary hypothesis was that the McGrath X-blade has a similar first-attempt success rate as the CMAC videolaryngoscope. 210 patients of ASA physical status I to III, aged 21 to 80 years old, undergoing general anesthesia requiring tracheal intubation were prospectively recruited into this two-centre randomized controlled trial, from June 2016 to April 2019. Patients with history of or predicted difficult airway, pre-existing dental risks, BMI > 35 kg/m², cervical spondylosis or myelopathy, aspiration risks, patients who declined to participate or lacked the mental capacity to give consent were excluded. Participants were intubated using either hyperangulated McGrath X-blade (MGX) or Macintosh-type CMAC (CM) videolaryngoscopy, with manual in-line stabilization. Primary outcome measured was first-attempt tracheal intubation success. Secondary outcomes included overall successful intubation within 2 attempts or 120 s, time to intubation, glottic view obtained and intubation-related complications. First-attempt success rates were 71.4% in the MGX group vs. 79.0% in the CM group (p = 0.26), with an absolute difference of -7.6% (95%CI -20%, 5.0%, p value = 0.26), but this trial was underpowered to detect a difference. Overall success was 91.4% (MGX) vs. 92.4% (CM) (p > 0.99). The Cormack & Lehane laryngeal grade was superior in the MGX group compared to CM group (Grade I: MGX 44%, CM 23%; Grade II: MGX 53%, CM 45%; Grade III: MGX 3%, CM 32%; p < 0.001). The median time to intubation using the MGX was longer than the CM [MGX 55.5 s (42.1-78.3), CM 43.8 s (38-55.3); p < 0.001]. Our study did not demonstrate a significant difference in efficacy between the McGrath X-blade and the CMAC videolaryngoscope. In patients with manual in-line stabilization, no anticipated airway difficulty and in the hands of experienced operators, the McGrath X-blade provided superior glottic views but conferred no advantage over the C-MAC, with a longer median time to intubation compared to the CMAC videolaryngoscope.Trial registration: Australian New Zealand Clinical Trial Registry (ACTRN12616000668404).

Association of Obstructive Sleep Apnea With Difficult Intubation: Prospective Multicenter Observational Cohort Study

BACKGROUND

Obstructive sleep apnea (OSA) has been found to be associated with difficult airway, although there is a paucity of prospective studies investigating thresholds of OSA severity with difficult airway outcomes. The aim of this study was to examine the association between OSA and difficult intubation or difficult mask ventilation. We also explored the utility of the Snoring, Tiredness, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, and Gender (STOP-Bang) score for difficult airway prediction.

METHODS

The Postoperative Vascular Complications in Unrecognized Obstructive Sleep Apnea (POSA) trial was an international prospective cohort study of surgical patients 45 years or older with one or more cardiac risk factor presenting for noncardiac surgery, with planned secondary analyses of difficult airway outcomes. Multivariable logistic regression analyses tested associations between OSA severity and predictors of difficult airway with difficult intubation or difficult mask ventilation. Overall, 869 patients without prior diagnosis of OSA were screened for OSA risk with the STOP-Bang tool, underwent preoperative sleep study, and had routine perioperative care, including general anesthesia with tracheal intubation. The primary outcome analyzed was difficult intubation, and the secondary outcome was difficult mask ventilation.

RESULTS

Based on the sleep studies, 287 (33%), 324 (37%), 169 (20%), and 89 (10%) of the 869 patients had no, mild, moderate, and severe OSA, respectively. One hundred and seventy-two (20%) had a STOP-Bang score of 0-2 (low risk), 483 (55%) had a STOP-Bang score of 3-4 (intermediate risk), and 214 (25%) had a STOP-Bang score 5-8 (high risk). The incidence of difficult intubation was 6.7% (58 of 869), and difficult mask ventilation was 3.7% (32 of 869). Multivariable logistic regression demonstrated that moderate OSA (odds ratio [OR] = 3.26 [95% confidence interval {CI}, 1.37-8.38], adjusted P = .010) and severe OSA (OR = 4.05 [95% CI, 1.51-11.36], adjusted P = .006) but not mild OSA were independently associated with difficult intubation compared to patients without OSA. Relative to scores of 0-2, STOP-Bang scores of 3-4 and 5-8 were associated with increased odds of difficult intubation (OR = 3.01 [95% CI, 1.13-10.40, adjusted P = .046] and 4.38 [95% CI, 1.46-16.36, adjusted P = .014]), respectively. OSA was not associated with difficult mask ventilation, and only increasing neck circumference was found to be associated (adjusted P = .002).

CONCLUSIONS

Moderate and severe OSA were associated with difficult intubation, and increasing neck circumference was associated with difficult mask ventilation. A higher STOP-Bang score of 3 or more may be associated with difficult intubation versus STOP-Bang score of 0-2. Anesthesiologists should be vigilant for difficult intubation when managing patients suspected or diagnosed with OSA.

Airway Management in Surgical Patients With Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder, and the difficult airway is perhaps the anesthesiologists' quintessential concern. OSA and the difficult airway share certain similar anatomical, morphological, and physiological features. Individual studies and systematic reviews of retrospective, case-control, and large database studies have shown a likely association between patients with OSA and the difficult airway; OSA patients have a 3- to 4-fold higher risk of difficult intubation, difficult mask ventilation, or a combination of both. The presence of OSA should initiate proactive perioperative management in anticipation of a difficult airway. Prudent intraoperative management comprises the use of regional anesthesia where possible and considering an awake intubation technique where there is the presence of notable difficult airway predictors and risk of rapid desaturation following induction of general anesthesia. Familiarity with difficult airway algorithms, cautious extubation, and appropriate postoperative monitoring of patients with OSA are necessary to mitigate perioperative risks.

Predictive performance of oximetry in detecting sleep apnea in surgical patients with cardiovascular risk factors

Introduction

In adults with cardiovascular risk factors undergoing major noncardiac surgery, unrecognized obstructive sleep apnea (OSA) was associated with postoperative cardiovascular complications. There is a need for an easy and accessible home device in predicting sleep apnea. The objective of the study is to determine the predictive performance of the overnight pulse oximetry in predicting OSA in at-risk surgical patients.

Methods

This was a planned post-hoc analysis of multicenter prospective cohort study involving 1,218 at-risk surgical patients without prior diagnosis of sleep apnea. All patients underwent home sleep apnea testing (ApneaLink Plus, ResMed) simultaneously with pulse oximetry (PULSOX-300i, Konica Minolta Sensing, Inc). The predictive performance of the 4% oxygen desaturation index (ODI) versus apnea-hypopnea index (AHI) were determined.

Results

Of 1,218 patients, the mean age was 67.2 ± 9.2 years and body mass index (BMI) was 27.0 ± 5.3 kg/m². The optimal cut-off for predicting moderate-to-severe and severe OSA was ODI ≥15 events/hour. For predicting moderate-to-severe OSA (AHI ≥15), the sensitivity and specificity of ODI ≥ 15 events per hour were 88.4% (95% confidence interval [CI], 85.7–90.6) and 95.4% (95% CI, 94.2–96.4). For severe OSA (AHI ≥30), the sensitivity and specificity were 97.2% (95% CI, 92.7–99.1) and 78.8% (95% CI, 78.2–79.0). The area under the curve (AUC) for moderate-to-severe and severe OSA was 0.983 (95% CI, 0.977–0.988) and 0.979 (95% CI, 0.97–0.909) respectively.

Discussion

ODI from oximetry is sensitive and specific in predicting moderate-to-severe or severe OSA in at-risk surgical population. It provides an easy, accurate, and accessible tool for at-risk surgical patients with suspected OSA.

Diagnostic performance of the STOP-Bang questionnaire as a screening tool for obstructive sleep apnea in different ethnic groups

STUDY OBJECTIVES

The STOP-Bang questionnaire is a concise and easy screening tool for obstructive sleep apnea (OSA). Using modified body mass index (BMI), we assessed the diagnostic performance of the STOP-Bang questionnaire in predicting OSA in ethnically different groups of patients undergoing surgery.

METHODS

This was a multicenter prospective cohort study involving patients with cardiovascular risk factors who were undergoing major noncardiac surgery. Patients underwent home sleep apnea testing. All patients completed the STOP-Bang questionnaire. The predictive parameters of STOP-Bang scores were calculated against the apnea-hypopnea index.

RESULTS

From 4 ethnic groups 1,205 patients (666 Chinese, 161 Indian, 195 Malay, and 183 Caucasian) were included in the study. The mean BMI ranged from 25 ± 4 to 30 ± 6 kg/m² and mean age ranged from 64 ± 8 to 71 ± 10 years. For the Chinese and Indian patients, diagnostic parameters are presented using BMI threshold of 27.5 kg/m² with the area under curve to predict moderate-to-severe OSA being 0.709 (0.665-0.753) and 0.722 (0.635-0.808), respectively. For the Malay and Caucasian, diagnostic parameters are presented using BMI threshold of 35 kg/m² with the area under curve for predicting moderate-to-severe OSA being 0.645 (0.572-0.720) and 0.657 (0.578-0.736), respectively. Balancing the sensitivity and specificity, the optimal STOP-Bang thresholds for the Chinese, Indian, Malay, and Caucasian groups were determined to be 4 or greater.

CONCLUSIONS

For predicting moderate-to-severe OSA, we recommend BMI threshold of 27.5 kg/m² for Chinese and Indian patients and 35 kg/m² for Malay and Caucasian patients. The optimal STOP-Bang threshold for the Chinese, Indian, Malay and Caucasian groups is 4 or greater.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Postoperative Vascular Events in Unrecognized Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/study/NCT01494181; Identifier: NCT01494181.

Time to consider supraglottic airway device oropharyngeal leak pressure measurement more objectively

Oropharyngeal leak pressure (OLP) is considered a measure of successful placement, adequate performance and is a useful comparator between supraglottic airway devices (SADs). OLP measurement is based on the premise that the SAD is sited properly in the hypopharynx after blind placements, but the evidence suggests otherwise. Several limitations and controversies surround OLP. This editorial addresses the uses and pitfalls of OLP, the rationale for and methods of ascertaining OLP, the pros and cons of OLP measurement and newer modalities to improve its accuracy.

A New Approach for Detecting Sleep Apnea Using a Contactless Bed Sensor: Comparison Study

Background

At present, there is an increased demand for accurate and personalized patient monitoring because of the various challenges facing health care systems. For instance, rising costs and lack of physicians are two serious problems affecting the patient’s care. Nonintrusive monitoring of vital signs is a potential solution to close current gaps in patient monitoring. As an example, bed-embedded ballistocardiogram (BCG) sensors can help physicians identify cardiac arrhythmia and obstructive sleep apnea (OSA) nonintrusively without interfering with the patient’s everyday activities. Detecting OSA using BCG sensors is gaining popularity among researchers because of its simple installation and accessibility, that is, their nonwearable nature. In the field of nonintrusive vital sign monitoring, a microbend fiber optic sensor (MFOS), among other sensors, has proven to be suitable. Nevertheless, few studies have examined apnea detection.

Objective

This study aims to assess the capabilities of an MFOS for nonintrusive vital signs and sleep apnea detection during an in-lab sleep study. Data were collected from patients with sleep apnea in the sleep laboratory at Khoo Teck Puat Hospital.

Methods

In total, 10 participants underwent full polysomnography (PSG), and the MFOS was placed under the patient’s mattress for BCG data collection. The apneic event detection algorithm was evaluated against the manually scored events obtained from the PSG study on a minute-by-minute basis. Furthermore, normalized mean absolute error (NMAE), normalized root mean square error (NRMSE), and mean absolute percentage error (MAPE) were employed to evaluate the sensor capabilities for vital sign detection, comprising heart rate (HR) and respiratory rate (RR). Vital signs were evaluated based on a 30-second time window, with an overlap of 15 seconds. In this study, electrocardiogram and thoracic effort signals were used as references to estimate the performance of the proposed vital sign detection algorithms.

Results

For the 10 patients recruited for the study, the proposed system achieved reasonable results compared with PSG for sleep apnea detection, such as an accuracy of 49.96% (SD 6.39), a sensitivity of 57.07% (SD 12.63), and a specificity of 45.26% (SD 9.51). In addition, the system achieved close results for HR and RR estimation, such as an NMAE of 5.42% (SD 0.57), an NRMSE of 6.54% (SD 0.56), and an MAPE of 5.41% (SD 0.58) for HR, whereas an NMAE of 11.42% (SD 2.62), an NRMSE of 13.85% (SD 2.78), and an MAPE of 11.60% (SD 2.84) for RR.

Conclusions

Overall, the recommended system produced reasonably good results for apneic event detection, considering the fact that we are using a single-channel BCG sensor. Conversely, satisfactory results were obtained for vital sign detection when compared with the PSG outcomes. These results provide preliminary support for the potential use of the MFOS for sleep apnea detection.

The neglected perioperative population of undiagnosed diabetics - a retrospective cohort study

BACKGROUND

Diabetes is known to increase morbidity and 30-day mortality in adults undergoing non-cardiac surgery, but longer term outcomes are less studied. This study was done to explore how undiagnosed and known diabetes affect 30-day and one-year morbidity and mortality outcomes. The secondary aim was to study the prevalence of undiagnosed diabetics in our perioperative Asian surgical population.

METHODS

A retrospective cohort study of 2106 patients aged > 45 years undergoing non-cardiac surgery in a single tertiary hospital was performed. Undiagnosed diabetics were identified (HbA1c ≥6.5% or fasting blood glucose ≥126 mg/dL) and relevant demographic, clinical and surgical data were analyzed to elicit the relationship to adverse outcomes. Univariate analysis was first performed to identify significant variables with p-values ≤0.1, which were then analyzed using multiple logistic regression to calculate the adjusted odds ratio.

RESULTS

The prevalence of undiagnosed diabetes was 7.4%. The mean and median HbA1c of known diabetics were 7.9 and 7.5%, while the mean and median HbA1c for undiagnosed diabetics were 7.2 and 6.8% respectively. 36.4% of known diabetics and 20.5% of undiagnosed diabetics respectively had a random blood glucose > 200 mg/dL. Undiagnosed diabetics had a three-fold increase in 1-year mortality compared to non-diabetics (adjusted OR 3.46(1.80-6.49) p < 0.001) but this relationship was not significant between known and non-diabetics. Compared to non-diabetics, known diabetics were at increased risks of new-onset atrial fibrillation (aOR 2.48(1.01-6.25) p = 0.047), infection (aOR 1.49(1.07-2.07) p = 0.017), 30-day readmission (aOR 1.62(1.17-2.25) p = 0.004) and 30-day mortality (aOR 3.11(1.16-8.56) p = 0.025).

CONCLUSIONS

Although undiagnosed diabetics have biochemically less severe disease compared to known diabetics at the point of testing, they are at a one-year mortality disadvantage which is not seen among known diabetics. This worrying trend highlights the importance of identifying and treating diabetes. Congruent to previous studies, known diabetics have higher morbidity and 30-day mortality compared to non-diabetics.

Choosing the best supraglottic airway for ophthalmic general anaesthesia: a manikin study

General anaesthesia is sometimes favoured over regional anaesthesia in ophthalmic surgery. The use of supraglottic airway (SGA) or laryngeal mask airway (LMA) as the primary airway device is increasing due to numerous advantages over tracheal intubation. Compared with 1st generation SGAs, 2nd generation SGAs have an added benefit of isolating the airway from the alimentary tract. However, the vertical profile of SGAs may encroach into the surgical field and hence interfere with surgery. We investigated the vertical projections of 1st generation SGAs (LMA Classic, Ambu AuraFlex) and commonly used 2nd generation SGAs in our institution (LMA ProSeal, LMA Supreme, LMA Protector, Ambu AuraGain and I-gel) in a manikin model. Each device was connected to a corrugated catheter mount or angled connector following insertion as per usual clinical practice in our institutions. Vertical projections of all devices were measured from the chin using a centimetre ruler. Securing of airway device to the chin with an adhesive tape was possible for the LMA Classic and Ambu AuraFlex with straight corrugated connector, whereas the stiffer 2nd generations SGAs required the addition of an angled connector or straight corrugated tubing to direct the airway tube caudally, away from the surgical field. The LMA ProSeal had the lowest vertical projection amongst the 2nd generation SGAs and may be the suitable choice for ophthalmic surgery. We also describe a novel technique of utilising a 1st generation SGA with placement of an orogastric tube, although with some reservations. This study has several limitations and transferability of our findings into clinical practice is questionable as the use of a manikin may not fully imitate the real condition of the patient. Our study is the first study comparing vertical projected height of different SGAs in manikin, but future studies should investigate the use of SGA in the clinical setting during ophthalmic surgery.

Factors predicting one-year post-surgical mortality amongst older Asian patients undergoing moderate to major non-cardiac surgery - a retrospective cohort study

BACKGROUND

While short-term perioperative outcomes have been well studied in Western surgical populations, the aim of this study is to look at the one-year perioperative mortality and its associated factors in an Asian surgical population after non-cardiac surgery.

METHODS

A retrospective cohort study of 2163 patients aged above 45 undergoing non-cardiac surgery in a university-affiliated tertiary hospital from January to July 2015 was performed. Relevant demographic, clinical and surgical data were analysed to elicit their relationship to mortality at one year after surgery. A univariate analysis was first performed to identify significant variables with p-values ≤ 0.2, which were then analysed using Firth multiple logistic regression to calculate the adjusted odds ratio.

RESULTS

The one-year mortality in our surgical population was 5.9%. The significant factors that increased one-year mortality include smoking (adjusted OR 2.17 (1.02-4.45), p = 0.044), anaemia (adjusted OR 1.32 (1.16-1.47), p < 0.001, for every 1 g/dL drop in haemoglobin level), lower BMI (adjusted OR 0.93 (0.87-0.98), p = 0.005, for every 1 point increase in BMI), Malay and Indian ethnicity (adjusted OR 2.68 (1.53-4.65), p = 0.001), peripheral vascular disease (adjusted OR 4.21 (1.62-10.38), p = 0.004), advanced age (adjusted OR 1.04 (1.01-1.06), p = 0.004, for every one year increase in age), emergency surgery (adjusted OR 2.26 (1.29-3.15), p = 0.005) and malignancy (adjusted OR 3.20 (1.85-5.52), p < 0.001).

CONCLUSIONS

Our study shows that modifiable risk factors such as malnutrition, anaemia and smoking which affect short term mortality extend beyond the immediate perioperative period into longer term outcomes. Identification and optimization of this subset of patients are therefore vital. Further similar large studies should be done to develop a risk scoring system for post-operative long-term outcomes. This would aid clinicians in risk stratification, counselling and surgical planning, which will help in patients' decision making and care planning.

Perioperative considerations and anesthesia management in patients with obstructive sleep apnea undergoing ophthalmic surgery

Obstructive sleep apnea (OSA) is a disorder characterized by breathing cessation caused by obstruction of the upper airway during sleep. It is associated with multiorgan comorbidities such as obesity, hypertension, heart failure, arrhythmias, diabetes mellitus, and stroke. Patients with OSA have an increased prevalence of ophthalmic disorders such as cataract, glaucoma, central serous retinopathy (detachment of retina, macular hole), eyelid laxity, keratoconus, and nonarteritic anterior ischemic optic neuropathy; and some might require surgery. Given that OSA is associated with a high incidence of perioperative complications and more than 80% of surgical patients with OSA are unrecognized, all surgical patients should be screened for OSA (eg, STOP-Bang questionnaire) with comorbidities identified. Patients suspected or diagnosed with OSA scheduled for ophthalmic surgery should have their comorbid conditions optimized. This article includes a review of the literature and highlights best perioperative anesthesia practices in the management of ophthalmic surgical patients with OSA.

Association of Unrecognized Obstructive Sleep Apnea With Postoperative Cardiovascular Events in Patients Undergoing Major Noncardiac Surgery

Importance

Unrecognized obstructive sleep apnea increases cardiovascular risks in the general population, but whether obstructive sleep apnea poses a similar risk in the perioperative period remains uncertain.

Objectives

To determine the association between obstructive sleep apnea and 30-day risk of cardiovascular complications after major noncardiac surgery.

Design, Setting, and Participants

Prospective cohort study involving adult at-risk patients without prior diagnosis of sleep apnea and undergoing major noncardiac surgery from 8 hospitals in 5 countries between January 2012 and July 2017, with follow-up until August 2017. Postoperative monitoring included nocturnal pulse oximetry and measurement of cardiac troponin concentrations.

Exposures

Obstructive sleep apnea was classified as mild (respiratory event index [REI] 5-14.9 events/h), moderate (REI 15-30), and severe (REI >30), based on preoperative portable sleep monitoring.

Main Outcomes and Measures

The primary outcome was a composite of myocardial injury, cardiac death, heart failure, thromboembolism, atrial fibrillation, and stroke within 30 days of surgery. Proportional-hazards analysis was used to determine the association between obstructive sleep apnea and postoperative cardiovascular complications.

Results

Among a total of 1364 patients recruited for the study, 1218 patients (mean age, 67 [SD, 9] years; 40.2% women) were included in the analyses. At 30 days after surgery, rates of the primary outcome were 30.1% (41/136) for patients with severe OSA, 22.1% (52/235) for patients with moderate OSA, 19.0% (86/452) for patients with mild OSA, and 14.2% (56/395) for patients with no OSA. OSA was associated with higher risk for the primary outcome (adjusted hazard ratio [HR], 1.49 [95% CI, 1.19-2.01]; P = .01); however, the association was significant only among patients with severe OSA (adjusted HR, 2.23 [95% CI, 1.49-3.34]; P = .001) and not among those with moderate OSA (adjusted HR, 1.47 [95% CI, 0.98-2.09]; P = .07) or mild OSA (adjusted HR, 1.36 [95% CI, 0.97-1.91]; P = .08) (P = .01 for interaction). The mean cumulative duration of oxyhemoglobin desaturation less than 80% during the first 3 postoperative nights in patients with cardiovascular complications (23.1 [95% CI, 15.5-27.7] minutes) was longer than in those without (10.2 [95% CI, 7.8-10.9] minutes) (P < .001). No significant interaction effects on perioperative outcomes were observed with type of anesthesia, use of postoperative opioids, and supplemental oxygen therapy.

Conclusions and Relevance

Among at-risk adults undergoing major noncardiac surgery, unrecognized severe obstructive sleep apnea was significantly associated with increased risk of 30-day postoperative cardiovascular complications. Further research would be needed to assess whether interventions can modify this risk.

Choosing anesthesia options for cataract surgery in patients with dementia

Background and Aims

Not all patients with dementia are the same, and Global Deterioration Scale (GDS) helps in staging dementia. Ophthalmologists usually prefer general anesthesia (GA) for cataract surgery in patients with dementia. We evaluated the impact of "Choosing Wisely" initiative on anesthesia options for cataract surgery in patients with dementia undergoing cataract surgery.

Material and Methods

A retrospective review of electronic perioperative database was performed over a 4-year period of patients with a specific diagnosis of dementia undergoing cataract surgery, after the introduction of the "Choosing Wisely" based on preoperative GDS assessment. Preferred method by the listing ophthalmologist, changes in anesthesia modality based on GDS, and the occurrence of intraoperative events were analyzed.

Results

One hundred and thirty-six patients with dementia underwent cataract surgery over a 4-year period. The mean patient age was 78 years, 73.5% female, and 55% ASA physical status III. GA was administered for GDS stage 6-7, and regional anesthesia (RA) for GDS stages 1-5. Surgery was uneventful under RA in 64% of the patients (87 out of 136), and 2% (3 patients) originally deemed suitable for RA were converted to GA.

Conclusions

The authors found a reduced requirement for GA when "Choosing Wisely' initiative was used based on the GDS stage.

Effectiveness of 3-in-1 Continuous Femoral Block of Differing Concentrations Compared to Patient Controlled Intravenous Morphine for Post Total Knee Arthroplasty Analgesia and Knee Rehabilitation

We assessed the effectiveness of the 3-in-l continuous femoral block as a form of postoperative pain relief for unilateral total knee arthroplasty (TKA). Sixty patients undergoing elective unilateral TKA under subarachnoid block were randomized into three groups. Postoperative analgesia was provided with a continuous 3-in-l femoral nerve catheter with 0.15% ropivacaine in group A, a continuous 3-in-l femoral nerve catheter with 0.2% ropivacaine in group B, or patient controlled intravenous morphine in group C (control group). Groups A and B received patient controlled intravenous morphine pumps for rescue analgesia. Patients in each group were followed for 72 hours postoperatively. Five patients were excluded after randomization. In the remaining 55 patients there was no statistical difference in pain score between the groups. Total morphine use was highest in group C (P< 0.05). No appreciable difference could be found with sensorimotor blockade, morphine usage and satisfaction scores when comparing groups A and B. Femoral catheter dislodgement rate was 7.9%. There was no statistical difference between the groups when comparing the day of first ambulation and the time to discharge from the hospital. Satisfaction scores were higher in group A (P = 0.028) and group B (P = 0.002) compared to group C. We conclude that a continuous 3-in-l femoral nerve block with ropivacaine 0.15% or 0.2% for elective unilateral TKA has an opioid-sparing effect.

Prevailing practices in airway management: a prospective single-centre observational study of endotracheal intubation

INTRODUCTION

Airway management during anaesthesia has potential difficulties and risks. We aimed to investigate the utility of routine airway assessment for predicting difficult tracheal intubation, review the prevailing practice of videolaryngoscope use amongst anaesthetists in a teaching hospital and determine the incidence of intraoperative and postoperative airway-related complications.

METHODS

A prospective observational study of 1,654 patients undergoing general anaesthesia with endotracheal intubation over a seven-month period was performed. Data regarding airway and anaesthetic management was collected and analysed.

RESULTS

Videolaryngoscopes were used as the first-choice equipment in 60.5% of the cohort. The incidence of difficult intubation was 2.1%, of which 45.7% of cases were unanticipated. The sensitivity of airway assessment was 54.3%, with a positive predictive value of 8.1%. When difficult intubation was anticipated, more videolaryngoscopes were used as the first equipment of choice compared to the Macintosh laryngoscope (p < 0.001). In the Macintosh group, more patients required a change of airway equipment (p = 0.015), but the number of intubation attempts was similar (p = 0.293). The incidence of intraoperative (p = 0.920) and postoperative complications (p = 0.380) were similar in both groups.

CONCLUSION

Using the current predictors of difficult intubation, half of the difficult airways we encountered were unanticipated. Videolaryngoscopes were preferred when difficulty was anticipated and were also used in routine tracheal intubation.

Laryngeal Mask Airway Protector™ for intubation and extubation in thyroid surgeries: A case report

The laryngeal mask airway (LMA) Protector™ has recently made its way into clinical practice. As little is reported on this novel supraglottic airway device, we describe our experiences through intubation and Bailey manoeuvre using the LMA Protector™, and the assessment of vocal cord mobility using a flexible bronchoscope through it in three patients undergoing hemithyroidectomies.

Laryngeal mask airway protector™: Advanced uses for laparoscopic cholecystectomies

The laryngeal mask airway (LMA) Protector™ is a second-generation perilaryngeal sealer type supraglottic airway device recently introduced into clinical practice. We describe our initial experiences with the use of the LMA Protector™ in three patients undergoing laparoscopic cholecystectomies. In all patients, we found the LMA Protector™ to have acceptable placements on the first attempt, adequate oropharyngeal leak pressures and ventilation adequacy.