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Biomedical subjects

A Y C Wong

Publications and source records attributed to A Y C Wong.

8 recordsLinked to original sources
PubMed2006

Total intravenous anaesthesia with propofol and remifentanil for elective neurosurgical procedures: an audit of early postoperative complications.

BACKGROUND AND OBJECTIVES: This was a prospective audit to assess the incidence and characteristics of early postoperative complications in the recovery room in extubated patients after elective neurosurgical procedures using propofol and remifentanil-based total intravenous anaesthesia. METHODS: Vital signs (temperature, conscious level, respiratory rate, oxygen saturation, pulse and blood pressure) and postoperative complications (shivering, nausea, vomiting and cardiorespiratory) were analysed in 145 adult patients over a 1-yr period. RESULTS: The overall shivering, postoperative nausea and vomiting and postoperative hypertension (systolic blood pressure more than 25% of the preoperative value) incidences were 30.3%, 16.6% and 35.2%, respectively. Fifty-one percent of the patients had at least one of the above complications. The complication rates were found to be widely different among various types of neurosurgery. The surgical procedures were divided into five groups: supratentorial craniotomy, posterior fossa craniotomy, intracranial vascular procedures, transphenoidal hypophysectomy and extracranial procedures. Median extubation time was similar in all groups and patients were fully conscious with no hypoxia in the recovery room. The intracranial vascular group had the highest shivering and postoperative nausea and vomiting rates (58.8% and 29.4%, respectively). In the supratentorial craniotomy group, 46% of the patients had hypertension. The overall complication rate (presence of any complications) was highest in the supratentfial craniotomy (55.4%), posterior fossa craniotomy (75%) and intracranial vascular (76.5%) groups. Shivering and overall complication rate was significantly related to the anaesthetic time (P<or=0.001 and 0.02, respectively). CONCLUSIONS: Despite the potential advantages of total intravenous anaesthesia in titratability, rapid return of consciousness and reduced respiratory complications, making it suitable for planned extubation at the end of neurosurgery, the postoperative complications of shivering, postoperative nausea and vomiting and hypertension were still high.

Anesthesia, Intravenous↗
PubMed2005

Large venous air embolism in the sitting position despite monitoring with transoesophageal echocardiography.

A 49-year-old male with neurofibromatosis type II was scheduled for posterior fossa craniotomy and excision of a right acoustic neuroma and placement of an auditory brainstem implant in the sitting position. Intra-operatively, the patient was monitored with transoesophageal echocardiography which detected two major episodes of venous air embolism. Despite immediate treatment the patient's gas exchange progressively worsened during surgery and a chest X-ray showed extensive bilateral pulmonary infiltrates. The patient developed acute respiratory distress syndrome and required inotropic support in the intensive care unit. Although transoesophageal echocardiography allowed rapid detection of venous air embolism, there was no evidence of therapeutic benefit.

Craniotomy↗
PubMed2002

Detecting synaptic connections in the medial nucleus of the trapezoid body using calcium imaging.

The study of synaptic transmission in brain slices generally entails the patch-clamping of postsynaptic neurones and stimulation of identified presynaptic axons using a remote electrical stimulating electrode. Although patch recording from postsynaptic neurones is routine, many presynaptic axons take tortuous turns and are severed in the slicing procedure, blocking propagation of the action potential to the synaptic terminal and preventing synaptic stimulation. Here we demonstrate a method of using calcium imaging to select postsynaptic cells with functional synaptic inputs prior to patch-clamp recording. We have used this method for exploring transmission in the auditory brainstem at the medial nucleus of the trapezoid body neurones, which are innervated by axons from the contralateral cochlear nucleus. Brainstem slices were briefly loaded with the calcium indicator fura-2 AM and stimulated with an electrode placed on the midline. Electrical stimulation caused a rise in intracellular calcium concentration in those postsynaptic neurones with active synaptic connections. Since <10% of the medial nucleus of the trapezoid body neurones retain viable synaptic inputs following the slicing procedure, preselecting those cells with active synapses dramatically increased our recording success. This detection method will greatly ease the study of synaptic responses in brain areas where suprathreshold synaptic inputs occur but connectivity is sparse.

Animals↗