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Biomedical subjects

A M-H Ho

Publications and source records attributed to A M-H Ho.

9 recordsLinked to original sources

Central apnoea after balanced general anaesthesia that included dexmedetomidine.

Dexmedetomidine is an alpha(2)-adrenoreceptor agonist that, in spite of its potent sedative, amnesic, and analgesic properties, has minimal respiratory depressant effect. Even at doses adequate for general anaesthesia, it does not cause central apnoea. Thus, it has been claimed that "combining alpha(2)-agonists with opiate narcotics or non-steroidal anti-inflammatory drugs can enhance the analgesic efficacy without increasing the respiratory depressant effect of the latter" and "the combination of alpha(2)-adrenoceptor agonists with opioids does not lead to further ventilatory depression". We present a case of central apnoea after general anaesthesia that included opioids and dexmedetomidine, and remind the readers that in susceptible patients, dexmedetomidine may cause life-threatening respiratory depression through potentiation of co-administered central nervous system depressants.

Adrenergic alpha-Agonists↗

Accuracy of central venous pressure monitoring during simultaneous continuous infusion through the same catheter.

Continuous central pressure monitoring and simultaneous continuous infusion via the same central venous catheter are sometimes necessary. Based on theoretical calculations and experimental measurements, we have determined that pressure monitoring is essentially unaffected if the continuous infusion rate is 50 ml.h(-1) or less for an adult and a paediatric central catheter. At rates > 200 ml.h(-1), the central venous pressure is exaggerated by up to 4 mmHg and 8 mmHg for the adult and paediatric catheters, respectively.

Adult↗

Right thoracic paravertebral analgesia for hepatectomy.

Haemostatic deficiencies, common among cirrhotic patients, may deteriorate further after hepatectomy, increasing the bleeding risk associated with the use of thoracic epidural analgesia. We describe two patients who enjoyed immediate post-operative tracheal extubation and satisfactory analgesia using mainly right thoracic paravertebral analgesia after right lobe hepatectomy.

Analgesia, Epidural↗

The margin of safety associated with the use of cuffed paediatric tracheal tubes.

There is increasing interest in the use of cuffed paediatric tracheal tubes, these tubes have a number of advantages and disadvantages. One disadvantage is the decreased margin of safety associated with the use of cuffed tracheal tubes. When using an uncuffed tube, the margin of safety is approximately the length of the trachea, however, for a cuffed tube, this margin is reduced and is the length of the trachea minus the distance between the proximal edge of the cuff and the and the tip of the tube. We have found that, compared with traditional uncuffed tubes, cuffed tubes may be associated with a reduced margin of safety of approximately 50% or more.

Age Factors↗