History and Current Status of Cardiac Anesthesia in Singapore.

Singapore is a small Southeast Asian island city-state located at the tip of the Malay peninsula with a population of 5.61 million people. It was a former British colony that went on to become a part of Malaysia before gaining independence in 1965. Since then, Singapore has developed tremendously from a small fishing village into the region's medical hub. This article will explore the roots of cardiac anesthesia in Singapore and how it has developed into a subspecialty today.

Transtracheal jet oxygenation: Comparing the efficacy and safety of two self-made Y-connector devices with the ENK oxygen flow modulator™ in an infant animal model.

BACKGROUND: Self-made Y-connector jet-oxygenation devices with wide-bore expiratory port have been described but not evaluated in infant models. Little is known about the effect of oxygen flow rates on jet oxygenation via transtracheal cannula. AIMS: The aim of this study was to compare two self-made Y-connector jet-oxygenation devices against the ENK oxygen flow modulator™, and the effects of three different oxygen flow rates based on body weight, in both unobstructed and obstructed airways, on the time to re-oxygenate in a rabbit infant model. The aim was also to assess the effectiveness of an oxygen flow rate of 1 L/min, for re-oxygenation using ENK oxygen flow modulator™. METHODS: Nine rabbits were grouped in threes: Group 1 had a Y-connector attached to an intravenous infusion tubing, Group 2 the same Y-connector attached to a perfusion oxygenator tubing and Group 3, ENK oxygen flow modulator™. From oxygen saturations of 75%, the rabbits were jet oxygenated using their assigned device for 10 minutes at each flow rate of 1 L/kg/min, 1.5 L/kg/min and 2 L/kg/min with their airways unobstructed and later, obstructed. Group 3 had additional experiments involving an absolute oxygen flow rate of 1 L/min. RESULTS: All devices resulted in rapid re-oxygenation within 40 seconds at flow rates of 1 L/kg/min. Oxygen flow rates beyond 1 L/kg/min in obstructed airways resulted in high airway pressures. All rabbits in Group 3 with obstructed airways died from barotrauma when jet oxygenated at a flow rate of 1.5 L/kg/min. When an oxygen flow rate of 1 L/min was used in Group 3, there was a failure to re-oxygenate to SpO2 90% within 120 seconds in some rabbits. CONCLUSION: Our animal model results suggest that self-made Y-connector jet-oxygenation devices with wide-bore expiratory port are efficacious and perhaps safer than ENK oxygen flow modulator™ in obstructed airways, and jet oxygenation with minimal oxygen flow rates starting at 1 L/kg/min or (age [years] + 4) L/min, whichever lower, should be considered.

A pilot study of dexmedetomidine sedation and caudal anesthesia for inguinal hernia repair in infants.

BACKGROUND: Recent concerns regarding possible long-term effects of early anesthesia exposure on neurodevelopment in children have provided an impetus to explore alternative anesthetic techniques using potentially neuroprotective agents. Dexmedetomidine has not been implicated in anesthesia-induced neurotoxicity and has been shown to be neuroprotective in preclinical studies. We describe a case series of 50 neonates and infants who received dexmedetomidine sedation with caudal anesthesia instead of general endotracheal anesthesia for inguinal hernia surgery. METHODS: We conducted a retrospective chart review on all neonates and infants who underwent inguinal hernia surgery with dexemetomidine sedation and caudal anesthesia in our institution. We started exploring this technique since October 2011 and established a protocol of administering dexmedetomidine 2 mcg·kg(-1) over 10 min, followed by 1 mcg·kg(-1) over the next 10 min. This led to satisfactory conditions for caudal placement in 20 min, with minimal need for airway intervention during surgery. RESULTS: The median gestational age of the infants was 31.4 (28.7, 36.0) weeks and median postconceptual age was 39.7 weeks (IQR 37.8, 45.7) at time of surgery. Of patients, 86% had surgery successfully completed under this technique alone. Seven patients required sevoflurane or nitrous oxide due to failed caudal block (n = 1) or difficult or prolonged surgery (n = 6). After establishing the sedation protocol and excluding patients with large or complicated hernias, the success rate was 96%. Transient intra-operative apnea or hypoventilation occurred in five patients and postoperative apnea in two patients. All respiratory events were easily reversed and no patient developed significant bradycardia or required intubation. CONCLUSIONS: Dexmedetomidine sedation with caudal anesthesia is a feasible alternative to spinal or general anesthesia in selected infants undergoing uncomplicated hernia surgery. It avoids the need for endotracheal intubation and may be potentially beneficial in avoiding the unknown effects of general anesthesia on neurodevelopment.

Association of anesthetic and surgical risk factors with outcomes of initial diagnostic biopsies in a current cohort of children with anterior mediastinal masses.

Background: Diagnostic biopsies of pediatric anterior mediastinal masses (AMMs) are high-risk procedures in which general anesthesia (GA) is traditionally avoided. However, awareness of historically recognized risk factors and corresponding perioperative management have improved over time and may now no longer strictly preclude the use of GA. Therefore, in this study, we examined the association of anesthetic and surgical risk factors and modalities with resulting procedural and survival outcomes in a current patient cohort. Methods: We retrospectively reviewed charts of 35 children with AMMs who underwent initial diagnostic biopsies between January 2001 and August 2019, and determined tracheal compression and deviation from archival CT scans and procedural and disease outcomes. Results: Twenty-three (65%) patients underwent GA while 12 (35%) received sedation. Among patients with available CT measurements, 13 of 25 (52%) had >50% anteroposterior tracheal diameter reduction. Patients with >50% anteroposterior tracheal compression received sedation more frequently (p=0.047) and were positioned upright (p=0.015) compared with patients with ≤50% compression, although 4 of 13 and 9 of 12, respectively, still received GA. Intraoperative adverse events (AEs) occurred in four (11.4%) patients: three received GA, and all were positioned supine or lateral. AEs were not associated with radiographic airway risk factors but were significantly associated with morphine and sevoflurane use (p<0.001) and with thoracoscopic biopsies (p=0.035). There were no on-table mortalities, but four delayed deaths occurred (three related to disease and one from late procedural complications). Conclusions: In a current cohort of pediatric AMM biopsies, patients with >50% anteroposterior tracheal compression were more frequently managed with a conservative perioperative management strategy, though not completely excluding GA. The corresponding reduction in frequency of procedural AEs in this traditionally high-risk group suggests that increased awareness of procedural risk factors and appropriate risk-guided perioperative management choices may obviate the procedural mortality historically associated with pediatric AMM biopsies.