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  1. Loh PS, Shariffuddin II, Chaw SH, Mansor M
    Med J Malaysia, 2021 01;76(1):98-100.
    PMID: 33510117
    Around June 2020, many institutions restarted full operating schedules to clear the backlog of postponed surgeries because of the first wave in the COVID-19 pandemic. In an online survey distributed among anaesthestists in Asian countries at that time, most of them described their safety concerns and recommendations related to the supply of personal protective equipment and its usage. The second concern was related to pre-operative screening for all elective surgical cases and its related issues. The new norm in practice was found to be non-standardized and involved untested devices or workflow that have since been phased out with growing evidence. Subsequent months after reinstating full elective surgeries tested the ability of many hospitals in handling the workload of non-COVID surgical cases together with rising COVID-19 positive cases in the second and third waves when stay-at-home orders eased.
  2. Foo LL, Chaw SH, Chan L, Ganesan D, Karuppiah R
    Rev Bras Anestesiol, 2016 09 28;67(6):655-658.
    PMID: 27692367 DOI: 10.1016/j.bjan.2015.09.006
    Tension pneumocephalus is rare but has been well documented following trauma and neurosurgical procedures. It is a surgical emergency as it can lead to neurological deterioration, brainstem herniation and death. Unlike previous cases where tension pneumocephalus developed postoperatively, we describe a case of intraoperative tension pneumocephalus leading to sudden, massive open brain herniation out of the craniotomy site. The possible causative factors are outlined. It is imperative to rapidly identify possible causes of acute intraoperative brain herniation, including tension pneumocephalus, and institute appropriate measures to minimize neurological damage.
  3. Ang E, Ng KT, Lee ZX, Ti LK, Chaw SH, Wang CY
    J Clin Anesth, 2020 Dec;67:110023.
    PMID: 32805685 DOI: 10.1016/j.jclinane.2020.110023
    OBJECTIVES: There is growing evidence on the influence of general anaesthesia (GA) in promoting the proliferation of cancer cells. The benefits of regional anaesthesia (RA) on cancer recurrence rate in cancer surgery remains unclear in the literature. The primary objective of this review was to examine the effect of RA on the incidence of post-operative cancer recurrence rate in cancer resection surgery.

    DESIGN: Systematic review and meta-analysis with trial sequential analysis.

    DATA SOURCES: Medline, EMBASE and CENTRAL were systematically searched from its inception until April 2020.

    ELIGIBILITY CRITERIA: All randomized control trials and observational studies comparing RA only versus GA in cancer resection surgery were included. Case report, case series and editorials were excluded.

    RESULTS: Ten retrospective observational studies (n = 9708; 4567 GA vs 5141 RA) were included for qualitative and quantitative meta-analysis. In comparison to GA, RA was not significantly associated with a lower cancer recurrence rate in cancer resection surgery (odds ratio 1.01, 95% CI 0.67 to 1.53, p = 0.95, certainty of evidence = very low). However, the trial sequential analysis for cancer recurrence rate was inconclusive. Our analysis demonstrated no significant difference between the RA and GA groups in the overall survival rate (odds ratio 1.51, 95% CI 0.65 to 3.51, p = 0.34, certainty of evidence = very low), time to cancer recurrence (mean difference 1.45 months, 95% CI -8.69 to 11.59, p = 0.78, certainty of evidence = very low), cancer-related mortality (odds ratio 1.79, 95% CI 0.57 to 5.62, p = 0.32, certainty of evidence = very low).

    CONCLUSIONS: Given the low level of evidence and underpowered trial sequential analysis, our review neither support nor oppose that the use of RA was associated with lower incidence of cancer recurrence rate than GA in cancer resection surgery.

    TRIAL REGISTRATION: CRD42020163780.

  4. Chaw SH, Chan L, Lee PK, Bakar JA, Rasiah R, Foo LL
    J Anesth, 2016 12;30(6):1063-1066.
    PMID: 27510560 DOI: 10.1007/s00540-016-2228-8
    We report a case of drug-induced myoclonus possibly related to palonosetron, a second-generation 5-hydroxytryptamine-3 receptor antagonist which was administered as a prophylaxis for postoperative nausea and vomiting in a 28-year-old female. The recurrent episodes of myoclonus jerk involving the head, neck and shoulder persisted for a period of 4 days. The patient also exhibited an episode of severe bradycardia leading to hypotension 7 h after surgery. To our knowledge, this is the first report presenting these adverse events potentially associated with the use of palonosetron.
  5. Chaw SH, Foo LL, Chan L, Wong KK, Abdullah S, Lim BK
    Rev Bras Anestesiol, 2016 09 28;67(6):647-650.
    PMID: 27687317 DOI: 10.1016/j.bjan.2016.09.003
    Anti-N-methyl-d-aspartate receptor encephalitis is a recently described neurological disorder and an increasingly recognized cause of psychosis, movement disorders and autonomic dysfunction. We report 20-year-old Chinese female who presented with generalized tonic-clonic seizures, recent memory loss, visual hallucinations and abnormal behavior. Anti-N-methyl-d-aspartate receptor encephalitis was diagnosed and a computed tomography scan of abdomen reviewed a left adnexal tumor. We describe the first such case report of a patient with anti-N-methyl-d-aspartate receptor encephalitis who was given a bilateral transversus abdominis plane block as the sole anesthetic for removal of ovarian tumor. We also discuss the anesthetic issues associated with anti-N-methyl-d-aspartate receptor encephalitis. As discovery of tumor and its removal is the focus of initial treatment in this group of patients, anesthetists will encounter more such cases in the near future.
  6. Foo LL, Shariffuddin II, Chaw SH, Lee PK, Lee CE, Chen YS, et al.
    Expert Rev Med Devices, 2018 Aug;15(8):597-603.
    PMID: 30095289 DOI: 10.1080/17434440.2018.1506329
    BACKGROUND: The Baska functional endoscopic sinus surgery (FESS) mask is a new supraglottic airway designed for head and neck procedures. This prospective, randomized controlled trial compared the oropharyngeal leak pressure (OLP) of the Baska FESS mask with the laryngeal mask airway (LMA) Supreme in different head and neck positions.

    METHODS: One hundred patients undergoing elective surgery were recruited. OLP was compared in supine position, 45° lateral rotation, 45° neck extension, and 30° neck flexion. Glottic view, insertion time, ease of insertion, number of attempts, ease and time of insertion of gastric tube, and complications were also compared.

    RESULTS: The OLP of the Baska FESS was higher than the LMA Supreme in all head and neck positions studied (p 

  7. Josephine C, Shariffuddin II, Chaw SH, Ng KWS, Ng KT
    Asian J Anesthesiol, 2021 03 01;59(1):7-21.
    PMID: 33504143 DOI: 10.6859/aja.202103_59(1).0002
    Dexmedetomidine is a highly selective α2-adrenoceptor agonist, which is off-labelled use for pediatric sedation. However, the hemodynamic responses of dexmedetomidine remain unclear in the pediatric population. The primary objectives of this systematic review and meta-analysis were to examine the hemodynamic effects of high-dose and low-dose dexmedetomidine in pediatric patients undergoing surgery. EMBASE, MEDLINE, and CENTRAL were systematically searched from its inception until April 2019. All randomized clinical trials comparing high-dose (> 0.5 mcg/kg) and low-dose (≤ 0.5 mcg/ kg) dexmedetomidine in pediatric surgical patients were included, regardless of the types of surgeries. Observational studies, case series, and case reports were excluded. Four trials (n = 473) were included in this review. Our review demonstrated that high-dose dexmedetomidine was associated with lower heart rate than low-dose dexmedetomidine after intravenous bolus of dexmedetomidine (studies, 3; n = 274; mean difference [MD], -5 [-6 to -4]; P < 0.0001) and during surgical stimulant (studies, 2; n = 153; MD, -11 [-13 to -9]; P < 0.0001). In comparison to the low-dose dexmedetomidine, high-dose dexmedetomidine was also associated with a significant longer recovery time (studies, 3; n = 257; MD, 5.90 [1.56 to 10.23]; P = 0.008) but a lower incidence of emergence agitation (studies, 2; n = 153; odds ratio, 0.17 [0.03 to 0.95]; P = 0.040). In this meta-analysis, low-dose dexmedetomidine demonstrated better hemodynamic stability with shorter recovery time than high-dose dexmedetomidine. However, these findings need to be interpreted with caution due to limited published studies, a small sample size, and a high degree of heterogeneity.
  8. Chaw SH, Shariffuddin II, Foo LL, Lee PK, Paran RM, Cheang PC, et al.
    J Clin Monit Comput, 2018 Dec;32(6):1093-1099.
    PMID: 29404890 DOI: 10.1007/s10877-018-0109-4
    To date, most of the studies on safety and efficacy of supraglottic airway devices were done in Caucasian patients, and the results may not be extrapolated to Asian patients due to the different airway anatomy. We conducted this study to compare Supreme™ LMA (SLMA) and Proseal™ LMA (PLMA) size 1.5 in anaesthetized children among an Asian population. This prospective randomized clinical trial was conducted in a tertiary teaching hospital from September 2013 until May 2016. Sixty children, weighing 5-10 kg, who were scheduled for elective surgery under general anaesthesia were recruited and completed the study. Patients were randomly assigned to have either SLMA or PLMA as the airway device for general anaesthesia, and standard anaesthesia protocol was followed. The primary outcome measured was the oropharyngeal leak pressure (OLP). The rate of successful insertion, insertion time, fibreoptic view of larynx and airway complications for each device were also assessed. There were no statistically significant differences between SLMA and PLMA size 1.5 in oropharyngeal leak pressure [19.1 (± 5.5) cmH2O vs. 19.8 (± 4.5) cmH2O, p = 0.68]. Secondary outcomes including time to insertion [20.8 (± 8.3) vs. 22.1 (± 8.3) s, p = 0.57], first attempt success rate for device insertion, fibreoptic view of larynx, and airway complications were also comparable between the two devices. We found that all the patients who had a failed device insertion (either PLMA or SLMA) were of a smaller size (5-6.2 kg). The oropharyngeal leak pressure of the SLMA 1.5 was comparable with the PLMA 1.5, and both devices were able to maintain an airway effectively without significant clinical complications in anaesthetized children from an Asian population.
  9. Chaw SH, Lo YL, Yeap LL, Haron DEBM, Shariffuddin II
    Eur J Drug Metab Pharmacokinet, 2023 Jan;48(1):11-21.
    PMID: 36207565 DOI: 10.1007/s13318-022-00795-4
    BACKGROUND AND OBJECTIVE: Oxycodone, a semisynthetic thebaine derivative µ-opioid (MOP) receptor agonist, is effective for treating moderate and severe pain in different clinical conditions. The pharmacokinetics of intravenous oxycodone in the obese population has not been studied. This study aims to characterize the pharmacokinetic profile of oxycodone after intravenous administration and to simulate an appropriate dosage for analgesic efficacy in obese patients.

    METHODS: We recruited 33 (age range from 21 to 72 years) adult patients with a body mass index of 30 kg/m2 and above, who were scheduled for non-cardiac surgeries. Intravenous oxycodone was administered after induction of general anesthesia and blood samples were collected up to 24 h after oxycodone administration. Plasma concentrations of oxycodone were assayed using liquid chromatography-tandem mass spectrometry and 253 concentration-time points were used for pharmacokinetic analysis using nonlinear mixed-effects modeling.

    RESULTS: Intravenous oxycodone pharmacokinetics were well described by a two-compartment open model. The estimated total clearance and central volume of distribution of oxycodone are 28.5 l/h per 70 kg and 56.4 l per 70 kg, respectively. Total body weight was identified as a significant covariate of the clearance and central volume of distribution. Dosing simulations based on the final model demonstrate that a starting dose of 0.10 mg/kg of intravenous oxycodone is adequate to achieve a target plasma concentration and repeated doses of 0.02 mg/kg may be administered at 1.5-h intervals to maintain a plasma concentration within an effective analgesic range.

    CONCLUSIONS: A population pharmacokinetic model using total body weight as a covariate supports the administration of 0.10 mg/kg of intravenous oxycodone as a starting dose and repeated doses of 0.02 mg/kg at 1.5-h intervals to maintain targeted plasma concentrations for analgesia in the obese adult population.

  10. Cheong CC, Ong SY, Lim SM, Wan A WZ, Mansor M, Chaw SH
    Expert Rev Med Devices, 2023 Feb;20(2):151-160.
    PMID: 36715659 DOI: 10.1080/17434440.2023.2174850
    PURPOSE: A previous study reported a shorter time to tracheal intubation by reducing percentage of glottic opening (POGO) view to <50% when intubating a normal adult airway using the GlidescopeTM blade. We evaluate the efficacy of reducing POGO to <50% when intubating patients with rigid cervical immobilization using CMACTM D blade.

    METHODS: One hundred and four adult patients were randomized to group POGO 100% or POGO <50% . Laryngoscopy was performed by advancing tip of the D blade at vallecula. POGO 100% was achieved by exerting upward force to displace epiglottis until glottic opening from the anterior commissure to inter arytenoid notch. POGO < 50% was acquired by withdrawing the D blade tip dorsally from vallecula. The primary outcome was time to intubation.

    RESULTS: The median time (IQR) to successful intubation was 29 (25-35) seconds for group POGO < 50% and 34 (28-40) seconds for group with POGO 100% (difference in medians, 5 seconds; 95% confidence interval, 2 to 8, p = 0.003). Complications were minor.

    CONCLUSION: Using the CMACTM D blade with a reduced POGO in patients with cervical spine immobilization resulted in faster tracheal intubation.

    TRIAL REGISTRATION: The trial is registered at ClinicalTrial.gov (CT.gov identifier: NCT04833166).

  11. Loh PS, Chaw SH, Shariffuddin II, Ng CC, Yim CC, Hashim NHM
    Anesth Analg, 2021 Jan;132(1):15-24.
    PMID: 33002931 DOI: 10.1213/ANE.0000000000005264
    BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic affected and overwhelmed many health care systems around the world at an unprecedented speed and magnitude with devastating effects. In developing nations, smaller hospitals were unprepared to face this outbreak nor had strategies in place to do so at the beginning. Here, we describe the preparation in an anesthetic department using simulation-based training over 2 weeks, as the number of cases rose rapidly.

    METHODS: Three areas of priority were identified as follows: staff safety, patient movement, and possible clinical scenarios based on simulation principles in health care education. Staff was rostered and rotated through stations for rapid-cycle deliberate practice to learn donning and doffing of personal protective equipment (PPE) and powered air-purifying respirator (PAPR). For difficult airway management, Peyton's 4 steps for skills training and Harden's Three Circle model formed the structure in teaching the core skills. Several clinical scenarios used system probing to elicit inadequacies followed by formal debriefing to facilitate reflection. Finally, evaluation was both immediate and delayed with an online survey after 1 month to examine 4 levels of reaction, learning, behavior, and impact based on the Kirkpatrick Model. Frequency and thematic analysis were then conducted on the quantitative and qualitative data, respectively.

    RESULTS: A total of 15 of 16 (93%) consultants, 16 (100%) specialists, and 81 (100%) medical officers in the department completed training within 2 consecutive weeks. Reaction and part of the learning were relayed immediately to trainers during training. In total, 42 (39%) trained staff responded to the survey. All were satisfied and agreed on the relevance of training. A total of 41 respondents (98%; 95% confidence interval [CI], 87-99) answered 16 of 20 questions correctly on identifying aerosol-generating procedures (AGP), indications for PPE, planning and preparation for airway management to achieve adequate learning. About 43% (95% CI, 27-59) and 52% (95% CI, 36-68) recalled donning and doffing steps correctly. A total of 92 responses from 33 respondents were analyzed in the thematic analysis. All respondents reported at least 1 behavioral change in intended outcomes for hand hygiene practice (20%), appropriate use of PPE (27%), and airway management (10%). The emerging outcomes were vigilance, physical distancing, planning, and team communication. Finally, the impact of training led to the establishment of institutional guidelines followed by all personnel.

    CONCLUSIONS: Simulation-based training was a useful preparation tool for small institutions with limited time, resources, and manpower in developing nations. These recommendations represent the training experience to address issues of "when" and "how" to initiate urgent "medical education" during an outbreak.

  12. Ng CC, Sybil Shah MHB, Chaw SH, Mansor MB, Tan WK, Koong JK, et al.
    Expert Rev Med Devices, 2021 Feb;18(2):203-210.
    PMID: 33322949 DOI: 10.1080/17434440.2021.1865796
    Background: Supraglottic airway devices have increasingly been used as the airway technique of choice in laparoscopic surgeries. This study compared the efficacy and safety of the Baska Mask with endotracheal tube (ETT) in patients undergoing elective laparoscopic cholecystectomy.Research design and methods: This single-center, prospective, randomized controlled trial recruited 60 patients aged 18-75 years with American Society of Anesthesiologists' classifications I to III. The time taken to achieve effective airway, number of attempts, ease of insertion, ventilation parameters, hemodynamics data, and pharyngolaryngeal complications were recorded.Results: The time taken to achieve effective airway was shorter for the Baska group (26.6 ± 4.7 vs. 47.2 ± 11.8 s; p
  13. Chaw SH, Lo YL, Lee JY, Wong JW, Zakaria WAW, Ruslan SR, et al.
    BMC Anesthesiol, 2021 01 15;21(1):20.
    PMID: 33451283 DOI: 10.1186/s12871-020-01229-x
    BACKGROUND: The Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) evaluates the patient-reported quality of pain management in adults. A validated APS-POQ-R is pivotal to guide effective pain management with better patient satisfaction. Previous studies revealed that subscales of "patients' perception of pain management" were unstable cross-culturally. This study aims to evaluate the construct validity of the APS-POQ-R in gynecological postoperative patients with a multi-cultural background using confirmatory factor analysis to allow comparisons among different a priori models at the latent factor level.

    METHODS: Patients aged 18 years old or above and who were scheduled for gynecology surgery were selected. Three different models with a combination of latent factors were based on a priori hypotheses from previous studies. The root-mean-squared error of approximation, comparative fit index, Tucker-Lewis Index, Chi-squared test, and change in Chi-squared statistic given a change in degrees of freedom between models were used to assess the model fit to the present data.

    RESULTS: A total of 302 patients completed the questionnaire. The five-factor model which was based on Gordon's study has an acceptable fit for the data and was superior when compared to the one-factor baseline model. Although the four-factor model, which originated from Botti's study, also demonstrates a good model fit, the "perception of care" construct was excluded in this model. The "perception of care" construct is conceptually important as patient-centered care has become the focus of quality improvement of pain service.

    CONCLUSIONS: The APS-POQ-R is easy to administer and is useful for quality evaluation in postoperative pain management. The present study demonstrates that a five-factor structure of the APS-POQ-R is the best fitting model in our patient sample. The results of this study provide further evidence to support the use of APS-POQ-R as a measurement tool for pain management evaluation in acute postoperative patients with a multi-cultural background.

  14. Shariffuddin II, Chaw SH, Ng LW, Lim CH, Zainal Abidin MF, Wan Zakaria WA, et al.
    BMC Anesthesiol, 2020 07 31;20(1):184.
    PMID: 32736516 DOI: 10.1186/s12871-020-01100-z
    BACKGROUND: The 4th National Audit Project of The Royal College of Anaesthetists and The Difficult Airway Society (NAP4) reported a higher incidence of supraglottic airway device (SAD) related pulmonary aspiration in obese patients especially with the first-generation SADs. The latest single-use SAD, the Protector™ provides a functional separation of the respiratory and digestive tracts and its laryngeal cuff with two ports allowing additional suction in tandem with the insertion of a gastric tube. The laryngeal cuff of LMA Protector™ allows a large catchment reservoir in the event of gastric content aspiration.

    METHODS: We evaluated the performance characteristics of the LMA Protector™ in 30 unparalysed, moderately obese patients. First attempt insertion rate, time for insertion, oropharyngeal leak pressure (OLP), and incidence of complications were recorded.

    RESULTS: We found high first and second attempt insertion rates of 28(93%) and 1(33%) respectively, with one failed attempt where no capnography trace could be detected, presumably from a downfolded device tip. The LMA Protector™ was inserted rapidly in 21.0(4.0) seconds and demonstrated high OLP of 31.8(5.4) cmH2O. Fibreoptic assessment showed a clear view of vocal cords in 93%. The incidence of blood staining on removal of device was 48%, postoperative sore throat 27%, dysphagia 10% and dysphonia 20% (all self-limiting, resolving a few hours postoperatively).

    CONCLUSIONS: We conclude that the LMA Protector™ was associated with easy, expedient first attempt insertion success, demonstrating high oropharyngeal pressures and good anatomical position in the moderately obese population, with relatively low postoperative airway morbidity.

    TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12617001152314 . Registered 7 August 2017.

  15. Chaw SH, Lo YL, Goh SL, Cheong CC, Tan WK, Loh PS, et al.
    Obes Surg, 2021 10;31(10):4305-4315.
    PMID: 34282569 DOI: 10.1007/s11695-021-05564-x
    BACKGROUND: Transversus abdominis plane (TAP) block and intraperitoneal local anesthetics (IPLA) are widely investigated techniques that potentially improve analgesia after bariatric surgery. The analgesic efficacy of TAP block has been shown in previous studies, but the performance of TAP block can be difficult in patients with obesity. We performed a systematic review and meta-analysis to compare the analgesic efficacy of TAP block and IPLA. An alternative technique is useful in clinical setting when TAP block is not feasible.

    METHODS: We searched PubMed, Embase, and CENTRAL from inception until August 2020 for randomized controlled trials comparing both techniques. The primary outcome was cumulative morphine consumption at 24 h. Secondary pain-related outcomes included pain score at rest and on movement at 2, 6, 12, and 24 h; postoperative nausea and vomiting; and length of hospital stay.

    RESULTS: We included 23 studies with a total of 2,178 patients. TAP block is superior to control in reducing opioid consumption at 24 h, improving pain scores at all the time points and postoperative nausea and vomiting. The cumulative opioid consumption at 24 h for IPLA is less than control, while the indirect comparison between IPLA with PSI and control showed a significant reduction in pain scores at rest, at 2 h, and on movement at 12 h, and 24 h postoperatively.

    CONCLUSIONS: Transversus abdominis plane block is effective for reducing pain intensity and has superior opioid-sparing effect compared to control. Current evidence is insufficient to show an equivalent analgesic benefit of IPLA to TAP block.

  16. Lai HY, Foo LL, Lim SM, Yong CF, Loh PS, Chaw SH, et al.
    Clin Auton Res, 2020 Feb;30(1):53-60.
    PMID: 29196938 DOI: 10.1007/s10286-017-0485-8
    PURPOSE: Comparison of hemodynamic profiles and pain scores in diabetic patients undergoing diabetic foot surgery receiving peripheral nerve block (PNB) or spinal anesthesia [subarachnoid block (SAB)].

    METHODS: This was a prospective, randomised controlled trial. We recruited diabetic patients aged > 18 years, American Society of Anesthesiologists class II-III, who were scheduled for unilateral diabetic foot surgery below the knee. All patients were assessed for autonomic dysfunction using the Survey of Autonomic Symptoms score. Participants were randomly assigned to receive either PNB or SAB for the surgery. Hemodynamic data, including usage of vasopressors, were recorded at 5-min intervals for up to 1 h after the induction of anesthesia. Pain scores were recorded postoperatively, and follow-up was done via telephone 6 months later.

    RESULTS: Compared to the PNB group, the SAB group had a larger number of patients with significant hypotension (14 vs. 1; p = 0.001) and more patients who required vasopressor boluses (6 vs. 0 patients). Compared to SAB group, the patients in the PNB group had a longer postoperative pain-free duration (9 vs. 4.54 h; p = 0.002) and lower pain scores 1 day after surgery (3.63 vs. 4.69; p = 0.01).

    CONCLUSION: Peripheral nerve block should be considered, whenever possible, as the first option of anesthesia for lower limb surgery in diabetic patients as it provides hemodynamic stability and superior postoperative pain control compared to SAB.

    TRIAL REGISTRATION: Clinical trial registry: ClinicalTrials.gov. ID NCT02727348.

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