Dr Josef Holzki

Immediate past President, Federation of European Associations of Paediatric Anaesthesia (FEAPA)

Q: How long has computer assisted and monitored anaesthesia been used for patients of four years and older?

A: For many years, complex, sophisticated artificial respiration devices have also existed for the tiniest premature babies and newborns. However, it is only recently that we could use computer-assisted anaesthesiology for patients in this age group.

Q: Why has it taken so long for modern technology to extend to this fragile group of patients?

A: This is primarily due to the market situation. This particular patient group awaiting surgery is a small segment of the market, and the development costs for these specific devices are extraordinarily high. Nevertheless, together with Dräger Medical my team and I adapted computer-assisted with Dr. Josef Holzki and his staff at Cologne’s Children’s Hospital adapted computer-assisted anaesthesia control TCA (Target Controlled Anaesthesia), which is already available for adult anaesthesia.With the software 3.05, the Zeus® 1 anaesthesia system also exerts expanded, automatic control of all anaesthetic gases that are particularly well suited for use in paediatric ventilation. The Zeus rebreathing system has one of the world’s smallest system volumes making it appropriate for ventilating very young children and newborns.

Q: So Zeus is the world’s first closed anaesthesia system with continuous gas flow that can be used on young children?

A: Premature infants with a birth weight less than 1000 g can also be anaesthetised with this device, using control options previously unavailable. Of course, this system does not reinvent newborn anaesthesia, but it has simply improved it by making it much safer. The system disallows incorrect respiration quantities, as an alarm sounds immediately and the system indicates the sources of danger. Especially premature lungs can quickly be damaged with inadequate respiration. In only minutes, pressure and expansion trauma can occur in the lung tissues (baro-volutrauma), which heals very slowly and can result in permanent damage. This can quickly turn into a vicious cycle of poor gas exchange and increasing respiratory pressures. Often these situations can cause very severe lung damage and even lead to death if inadequate respiration settings are not immediately recognised and corrected. A vital factor in this anaesthesiology system is the continuous anaesthetic gas flow during the expiration phase, which will wash out the carbonic acid accumulated and concentrated in the Y-piece of the ventilation hose system at the rate of 24 litres per minute. Despite this high flow of gas, the anaesthetic system remains completely closed. Only the expired gases (for this age group extremely low) are reapportioned.

Q: If it is better for the lung in a 1000 g premature infant, then it should also be better for an adult?

A: This conclusion is correct. However, the majority of anaesthesiologists believe that continuous gas flow in expiration is a technique used only for small children, which is incorrect. Also for adults, especially those suffering from lung diseases, the continuous expiratory gas flow will allow the setting of a lower draw volume at lower respiration pressures. This cannot be achieved to such an extent using conventional anaesthesia respiration devices. For the paediatric anaesthesiologist presenting this uncomplicated phenomenon to a large audience, it is always very surprising to find out that the benefits of Zeus are not acknowledged. Too many anaesthesiologists are satisfied and feel safe with measuring the expiratory CO2.

However, the fact remains that this measured value is very complex and sometimes reflects only a dead space measurement, which will show dangerously high CO2 values when testing the arterial blood gases. With Zeus, we can now show dynamic ventilation trends: first by the pressure-volume breath flow; and secondly – and far more significantly – by verifying the alveolar ventilation using different respiration models. To avoid being at the mercy of any further speculation, it has been proven that better ventilation can be achieved using less pressure and intelligent pressure curve progression than can be achieved, by for example, a volume-controlled respiration. For artificial respiration of premature babies and newborns, the best computer-assisted anaesthetic device is a questionable advantage if it is not operated by experienced paediatric anaesthesiologists knowledgeable in neonatology. The systematic training of paediatric anaesthesiologists in Germany could still be improved, but we are well on our way, as indicated in the recent guidelines and recommendations for further education in paediatric anaesthesiology issued by the European Federation for Paediatric Anaesthesiology and published by the German Association for Anaesthesiology and Intensive Care Medicine. These offer hope that the youngest patients, who have their whole life ahead of them, will be anesthetised by the best educated anaesthesiologists with a command of the most modern devices.

Excerpts from an article with Dr Josef Holzki (Adapted for Infants, c.a.r.e 02/2006), Chief Physician in the Department for Anaesthesia and Intensive Care Medicine at Children’s Hospital, Cologne and Immediate past President of the Federation of European Associations of Paediatric Anaesthesia (FEAPA).

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