Anaesthesia
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The impact of cricoid pressure on laryngoscopy is unknown. We have developed a quantitative method of recording the laryngoscopic view using a rigid, zero-degree endoscope. We found that an image matching the laryngoscopist's view could be obtained by positioning the endoscope along the laryngoscopist's 'line of sight'. ⋯ We identified five subjects with a good initial view (anteroposterior length of the rima glottidis > 5 mm) who showed a marked deterioration in laryngoscopic view as cricoid pressure increased; in three of these subjects this progressed to obscure the larynx completely at a force of 30 N, 40 N and 60 N, respectively. We conclude that the effect of cricoid pressure on laryngoscopy is complex. However, in some individuals, a force close to that currently recommended (30 N) may cause a complete loss of the glottic view.
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Randomized Controlled Trial Comparative Study Clinical Trial
Randomised trial of intravenous infusion of ephedrine or mephentermine for management of hypotension during spinal anaesthesia for Caesarean section.
This study compared the effects of intravenous infusions of ephedrine and mephentermine for maintenance of maternal arterial pressure and neonatal outcome in pregnant women receiving subarachnoid block for lower segment Caesarean section. Sixty patients who developed hypotension following subarachnoid block for Caesarean section were randomly divided into two groups of 30 each to receive an intravenous infusion of ephedrine or mephentermine. Hypotension was defined as a decrease in systolic blood pressure of > or = 20% from the baseline value or an absolute value of <100 mmHg, whichever was higher. ⋯ Baseline haemodynamic parameters, haemodynamic changes subsequent to the start of vasopressor infusion, duration of hypotension and amount of vasopressor required were statistically similar for both groups. Neonatal APGAR scores and acid-base profiles were also comparable. To conclude, mephentermine can be used as safely and effectively as ephedrine for the management of hypotension during spinal anaesthesia in patients undergoing elective Caesarean section.
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The Glidescope is a new videolaryngoscope. It has a digital camera incorporated in the blade which displays a view of the vocal cords on a monitor. This allows the placement of a tracheal tube to be visualised. ⋯ The Glidescope improved the view by one grade in 22 and by two grades in one patient. We conclude that the Glidescope is an effective device for tracheal intubation and provides an improved view of the larynx. Further clinical studies are necessary to evaluate its role in airways that are difficult to manage.
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Case Reports
Interaction between infusion equipment resulting in drug overdose in a critically ill patient.
A critically ill septic patient on haemofiltration for acute renal failure suffered sudden circulatory and respiratory collapse. The cause of the collapse was traced to an interaction between mechanical devices (syringe driver infusion pumps and haemofiltration equipment) connected to two central venous catheters.