Anaesthesia 2013, 68, 1274–1287 2. Carlisle JB. The quick and the dead. Anaesthesia 2013; 68: 799–803.
Correspondence
sures during their study, to help address these issues?
Entrapment of power cable
C. Johnstone Liverpool Heart and Chest Hospital Liverpool, UK Email: [email protected]
During elective surgery under spinal anaesthesia and target-controlled propofol sedation, adjustment of a GE S5 monitor mount (GE Healthcare, Chalfont St Giles, UK, part number 1009-8228-000) resulted in an explosion and loss of power to both the GE Avance anaesthetic machine and the monitor. The patient was uninjured, and surgery proceeded using portable monitoring. On investigation, the hinged monitor mounting arm was found to have partially sheared through a power cable to the forced-air warming device used during surgery (Fig. 1). The resultant short circuit had melted a fuse in the ceiling pendant and caused power failure to all attached devices, including the anaesthetic machine and monitor. Similar impingement damage to power cables overlying monitor mounts was found on anaesthetic machines in other theatres, and
doi:10.1111/anae.12506
Brain oxygenation – does raised intracranial pressure play a role? I read with interest the recent study by Yu et al. [1] and wondered whether the authors had some thoughts on the following comments. It has been demonstrated that intracranial pressure (ICP) can increase by up to 60 mmHg during cardiopulmonary resuscitation (CPR), related to both increased intrathoracic pressures and the method of CPR, with greater rises seen during simultaneous compression-ventilation compared with conventional CPR. The transmission of intrathoracic pressure is further increased by a high baseline ICP [2, 3]. The reasoning behind this is complex but both valveless vascular and cerebrospinal fluid transmission mechanisms are thought to be involved. Given this, the assumption that tongue oxygen levels might accurately reflect cerebral oxygen levels is therefore unlikely to hold true. This may also explain why the authors experienced a slower response in the decline in tongue muscle oxygen. For the same reason, carotid blood flow during CPR is unlikely to correlate well with cerebral blood flow. I wonder whether the authors had considered measuring both intrathoracic and intracerebral pres-
1282
No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Yu J, Ramadeen A, Tsui AKY, et al. Quantitative assessment of brain microvasculature and tissue oxygenation during cardiac arrest and resuscitation in pigs. Anaesthesia 2013; 68: 713–22. 2. Gureci AD, Shi AY, Levin H, et al. Transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs. Circulation Research 1985; 56: 20–30. 3. Rogers MC, Nugent SK, Stidham GL. Effects of closed cardiac massage on intracranial pressure. Critical Care Medicine 1997; 7: 454–6. doi:10.1111/anae.12470
Figure 1 Power cable to forced air warming device, damaged by entrapment between anaesthetic machine (soot-marked) and monitor mount (right).
© 2013 The Association of Anaesthetists of Great Britain and Ireland
Correspondence
sures during their study, to help address these issues?
Entrapment of power cable
C. Johnstone Liverpool Heart and Chest Hospital Liverpool, UK Email: [email protected]
During elective surgery under spinal anaesthesia and target-controlled propofol sedation, adjustment of a GE S5 monitor mount (GE Healthcare, Chalfont St Giles, UK, part number 1009-8228-000) resulted in an explosion and loss of power to both the GE Avance anaesthetic machine and the monitor. The patient was uninjured, and surgery proceeded using portable monitoring. On investigation, the hinged monitor mounting arm was found to have partially sheared through a power cable to the forced-air warming device used during surgery (Fig. 1). The resultant short circuit had melted a fuse in the ceiling pendant and caused power failure to all attached devices, including the anaesthetic machine and monitor. Similar impingement damage to power cables overlying monitor mounts was found on anaesthetic machines in other theatres, and
doi:10.1111/anae.12506
Brain oxygenation – does raised intracranial pressure play a role? I read with interest the recent study by Yu et al. [1] and wondered whether the authors had some thoughts on the following comments. It has been demonstrated that intracranial pressure (ICP) can increase by up to 60 mmHg during cardiopulmonary resuscitation (CPR), related to both increased intrathoracic pressures and the method of CPR, with greater rises seen during simultaneous compression-ventilation compared with conventional CPR. The transmission of intrathoracic pressure is further increased by a high baseline ICP [2, 3]. The reasoning behind this is complex but both valveless vascular and cerebrospinal fluid transmission mechanisms are thought to be involved. Given this, the assumption that tongue oxygen levels might accurately reflect cerebral oxygen levels is therefore unlikely to hold true. This may also explain why the authors experienced a slower response in the decline in tongue muscle oxygen. For the same reason, carotid blood flow during CPR is unlikely to correlate well with cerebral blood flow. I wonder whether the authors had considered measuring both intrathoracic and intracerebral pres-
1282
No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesia correspondence.com.
References 1. Yu J, Ramadeen A, Tsui AKY, et al. Quantitative assessment of brain microvasculature and tissue oxygenation during cardiac arrest and resuscitation in pigs. Anaesthesia 2013; 68: 713–22. 2. Gureci AD, Shi AY, Levin H, et al. Transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs. Circulation Research 1985; 56: 20–30. 3. Rogers MC, Nugent SK, Stidham GL. Effects of closed cardiac massage on intracranial pressure. Critical Care Medicine 1997; 7: 454–6. doi:10.1111/anae.12470
Figure 1 Power cable to forced air warming device, damaged by entrapment between anaesthetic machine (soot-marked) and monitor mount (right).
© 2013 The Association of Anaesthetists of Great Britain and Ireland
