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  1. Vohra SB, Kumar CM
    Eye (Lond), 2023 Feb;37(3):548-553.
    PMID: 35220400 DOI: 10.1038/s41433-022-01979-7
    AIMS: This international survey was conducted to study the impact of Covid-19 pandemic on the provision and practices of ophthalmic anaesthesia, evaluate the methods employed by parent ophthalmic units for safeguarding their anaesthesia providers and patients during lockdown, and to assess pandemic's effect on anaesthesia providers as individuals. The study was done with the hope that the results will help in protecting patients and safeguarding precious human resource by better management if this pandemic was to continue or there was to be another pandemic.

    METHODS: An anonymous questionnaire survey was distributed electronically between December 2020-January 2021 to the practicing ophthalmic anaesthesia providers in different parts of the world.

    RESULTS: The survey identified that apart from reducing elective operating services, the ophthalmic units were ill prepared for the pandemic and the overall management was lacklustre. There was a definite lack of effective peri-operative patient screening, and, streaming processes. Measures for personal protection of staff were not optimal especially during regional/local ophthalmic anaesthesia. Severity of the pandemic, sudden job plan changes, and redeployment to intensive care units/acute covid wards had an adverse psychological impact on the affected staff.

    CONCLUSION: Ophthalmic anaesthesia services worldwide have had poor attentiveness to the life-threatening menace and reality of Covid-19 pandemic. A review of the institutional practices to address correctible deficiencies is urgently required. Robust, mandatory, elective, timely preventative strategies need to be implemented to protect patients, and, the precious ophthalmic workforce from potential adverse physical and psychological injuries.

  2. Tan LZ, Seet E, Kumar CM
    J Clin Monit Comput, 2022 Dec;36(6):1907-1908.
    PMID: 35616796 DOI: 10.1007/s10877-022-00850-0
    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.
  3. Ahmed R, Sinnathambi CM, Eldmerdash U, Subbarao D
    ScientificWorldJournal, 2014;2014:758137.
    PMID: 24672368 DOI: 10.1155/2014/758137
    Limited information is available about the thermodynamic evaluation for biomass gasification process using updraft gasifier. Therefore, to minimize errors, the gasification of dry refinery sludge (DRS) is carried out in adiabatic system at atmospheric pressure under ambient air conditions. The objectives of this paper are to investigate the physical and chemical energy and exergy of product gas at different equivalent ratios (ER). It will also be used to determine whether the cold gas, exergy, and energy efficiencies of gases may be maximized by using secondary air injected to gasification zone under various ratios (0, 0.5, 1, and 1.5) at optimum ER of 0.195. From the results obtained, it is indicated that the chemical energy and exergy of producer gas are magnified by 5 and 10 times higher than their corresponding physical values, respectively. The cold gas, energy, and exergy efficiencies of DRS gasification are in the ranges of 22.9-55.5%, 43.7-72.4%, and 42.5-50.4%, respectively. Initially, all 3 efficiencies increase until they reach a maximum at the optimum ER of 0.195; thereafter, they decline with further increase in ER values. The injection of secondary air to gasification zone is also found to increase the cold gas, energy, and exergy efficiencies. A ratio of secondary air to primary air of 0.5 is found to be the optimum ratio for all 3 efficiencies to reach the maximum values.
  4. Chua AW, Kumar CM, Chua MJ, Harrisberg BP
    Anaesth Intensive Care, 2020 Nov;48(6):430-438.
    PMID: 33198476 DOI: 10.1177/0310057X20957018
    Thyroid eye disease is an autoimmune inflammatory disorder of the orbit in adults. It causes inflammation, expansion and fibrosis of orbital fat, muscles and the lacrimal gland, leading to facial disfigurement, functional disability and, in severe cases, blindness. Overall, approximately 20% of affected patients need some form of surgical intervention requiring anaesthesia. This narrative review explores the background of thyroid eye disease, surgical procedures performed and their implications for anaesthesia. General anaesthesia is used for orbital decompression procedures, strabismus correction surgery and complex oculoplastic procedures. Local anaesthetic infiltration or regional anaesthesia under monitored anaesthesia care are the techniques most commonly employed for eyelid retraction surgery. It is important to limit the volume of local anaesthetic agent used during infiltration and continuously monitor the orbital volume and ocular pressure with a ballottement technique. In addition, the contralateral eye should be checked and, if necessary, protected against corneal exposure. Retrobulbar, peribulbar and sub-Tenon's blocks are best avoided. Topical anaesthesia has been used for some strabismus correction surgery but its use is limited to motivated and cooperative patients only.
  5. Chua AW, Kumar CM, Harrisberg BP, Eke T
    Anaesth Intensive Care, 2023 Mar;51(2):107-113.
    PMID: 36524304 DOI: 10.1177/0310057X221111183
    Ocular hypotony can occur from many causes, including eye trauma, ophthalmic surgery and ophthalmic regional anaesthesia-related complications. Some of these patients require surgical intervention(s) necessitating repeat anaesthesia. While surgical management of these patients is well described in the literature, the anaesthetic management is seldom discussed. The hypotonous eye may also have altered globe anatomy, meaning that the usual ocular proprioceptive feedbacks during regional ophthalmic block may be altered or lost, leading to higher risk of inadvertent globe injury. In an 'open globe' there is a risk of sight-threatening expulsive choroidal haemorrhage as a consequence of ophthalmic block or general anaesthesia. This narrative review describes the physiology of aqueous humour, the risk factors associated with ophthalmic regional anaesthesia-related ocular hypotony, the surgical management, and a special emphasis on anaesthetic management. Traumatic hypotony usually requires urgent surgical repair, whereas iatrogenic hypotony may be less urgent, with many cases scheduled as elective procedures. There is no universal best anaesthetic technique. Topical anaesthesia and regional ophthalmic block, with some technique modifications, are suitable in many mild-to-moderate cases, whilst general anaesthesia may be required for complex and longer procedures, and severely distorted globes.
  6. Chua AW, Chua MJ, Harrisberg BP, Kumar CM
    Anaesth Intensive Care, 2024 Mar;52(2):82-90.
    PMID: 38041616 DOI: 10.1177/0310057X231215826
    Two recent cases of central retinal artery occlusion under otherwise uncomplicated sub-Tenon's block that resulted in significant visual loss after cataract surgery prompted us to undertake a literature review of such cases. We identified 97 cases of retinal artery occlusion after ophthalmic surgery under regional anaesthesia that had no immediate signs of block-related complications. These occurred after various intraocular (87%) and extraocular (13%) operations, across a wide range of ages (19-89 years) on patients with (59%) or without (39%) known risk factors. The anaesthetic techniques included 40 retrobulbar blocks, 36 peribulbar blocks, 19 sub-Tenon's blocks, one topical anaesthetic and one unspecified local anaesthetic. Different strengths of lidocaine, bupivacaine, mepivacaine and ropivacaine, either alone or in various combinations, were used. The details of the anaesthetic techniques were often incomplete in the reports, which made comparison and analysis difficult. Only nine cases had their cause (optic nerve sheath injury) identified, while the mechanism of injury was unclear in the remaining patients. Various mechanisms were postulated; however, the cause was likely to be multifactorial due to patient, surgical and anaesthetic risk factors, especially in those with compromised retinal circulation. As there were no definite risk factors identified, no specific recommendations could be made to avoid this devastating outcome. We have provided rationales for some general considerations, which may reduce this risk, and propose anaesthetic options for ophthalmic surgery on the fellow eye if required, based both on our literature review and our personal experience.
  7. Kumar CM, Palte HD, Chua AWY, Sinha R, Shah SB, Imani F, et al.
    Anesth Pain Med, 2021 Apr;11(2):e113750.
    PMID: 34336627 DOI: 10.5812/aapm.113750
    Schizophrenia is ranked among the top 10 global burdens of disease. About 1% of people meet the diagnostic criteria for this disorder over their lifetime. Schizophrenic patients can develop cataract, particularly related to age and medications, requiring surgery and anesthesia. Many concerning factors, including cognitive function, anxiety, behavioral issues, poor cooperation and paroxysmal movements, may lead to general anesthesia as the default method. Antipsychotic agents should be continued during the perioperative period if possible. Topical/regional anesthesia is suitable in most schizophrenic patients undergoing cataract surgery. It reduces potential drug interactions and many postoperative complications; however, appropriate patient selection is paramount to its success. General anesthesia remains the primary technique for patients who are considered unsuitable for the topical/regional technique. Early involvement of a psychiatrist in the perioperative period, especially for patients requiring general anesthesia, is beneficial but often under-utilized. This narrative review summarizes the anesthetic considerations for cataract surgery in patients with schizophrenia.
  8. Seet E, Chung F, Wang CY, Tam S, Kumar CM, Ubeynarayana CU, et al.
    Anesth Analg, 2021 07 01;133(1):196-204.
    PMID: 33720906 DOI: 10.1213/ANE.0000000000005479
    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.

  9. Obaidur Rab S, Altalbawy FMA, Chandra M, Ariffin IA, Kaur P, Rathore G, et al.
    Pathol Res Pract, 2024 Dec;264:155679.
    PMID: 39500198 DOI: 10.1016/j.prp.2024.155679
    Lung malignancies are among the most prevalent and foremost causes of tumor-related deaths. Despite significant advancements in the understanding and management of lung cancer, resistance to traditional treatments remains a significant challenge. Understanding and targeting tumor microenvironment (TME) have attracted interest in the recent decade for eliminating various solid tumors. The lung TME has a crucial position in tumor expansion and therapy failure, driving it an engaging target for novel medicinal interventions. Plant-derived products offer a promising avenue for targeting TME due to their diverse chemical structures and biological activities. However, their clinical use is hindered by insufficient bioavailability and also possible systemic toxicity. The use of nanoparticles as delivery vehicles for natural products can overcome these challenges and enhance their therapeutic efficacy. This review article explores the potential of plant-derived products as medicinal agents for targeting lung TME. We provide an outline of the present knowledge of lung TME and explain the mechanisms by which plant-derived products can modulate key components of this microenvironment. The promising impacts and properties of nanoparticles for the delivery of these derivatives into lung tumors will also be discussed. We also review the preclinical and clinical findings for supporting the usefulness of these agents in targeting lung TME. Additionally, we highlight the challenges and forthcoming trends in the development of plant-derived products as targeted therapies for lung cancer, with a particular focus on combination therapies.
  10. Chai CA, Teoh YC, Tailly T, Emiliani E, Inoue T, Tanidir Y, et al.
    Minerva Urol Nephrol, 2023 Aug;75(4):493-500.
    PMID: 37293816 DOI: 10.23736/S2724-6051.23.05239-4
    BACKGROUND: Retrograde Intrarenal Surgery (RIRS) is recommended as an alternative to percutaneous nephrolithotomy for stones up to 2 cm. Pre-stenting before RIRS remains controversial with various studies differing in outcomes and recommendations. We aim to understand how pre-stenting influences surgical outcomes.

    METHODS: A number of 6579 patients from the TOWER group registry were divided into pre-stented (group 1) and non-pre-stented groups (group 2). Patients aged ≥18 years old, with normal calyceal anatomy were enrolled. Patients with ureteric stones, anomalous kidneys, bilateral stones, planned for ECIRS were excluded.

    RESULTS: Patients are homogeneously distributed in both groups (3112 vs. 3467). The predominant indication for pre-stenting was symptom relief. Overall stone size was comparable, whilst group 1 had a significantly more multiple (1419 vs. 1283, P<0.001) and lower-pole (LP) stones (1503 vs. 1411, P<0.001). The mean operative time for group 2 was significantly longer (68.17 vs. 58.92, P<0.001). Stone size, LP stones, age, recurrence and multiple stones are contributing factors for residual fragments at the multivariable analysis. The incidence of postoperative day 1 fever and sepsis was significantly higher in group 2, indicating that pre-stenting is associated with a lower risk of post-RIRS infection and a lower overall complications rate (13.62% vs. 15.89%) (P<0.001).

    CONCLUSIONS: RIRS without pre-stenting can be considered safe without significant morbidity. Multiple, lower-pole and large stone is a significant contributor towards residual fragments. Patients who were not pre-stented had significantly higher but low-grade complications, especially for lower pole and large volume stones. While we do not advocate routine pre-stenting, a tailored approach for these patients should include proper counselling regarding pre-stenting.

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