“Suctioning of paediatric critical care patientS iS an example of how the
application of eBp makeS a huge difference to the moSt vulneraBle patientS”
Given the above, the fact that epithelial damage is a common finding in animal studies of deep suctioning and that suctioning commonly causes deleterious changes in hemodynamic parameters and in lung volumes the necessity for using the optimum method for each individual patient and reducing the number of suction passes we administer is obvious. The evidence base can help us reach this goal.
Image © Rashid Hospital Dubai
CONTROVERSY #2: IN-LINE OR OPEN? Studies comparing open and in-line or ‘closed’ suctioning methods have taken account of the following: Suction efficacy in terms of secretion removal Oxygenation changes (PO2, SpO2) Haemodynamics Lung volume change and re-recruitment of alveoli post suction. Choong et al (2003) studied 14 children aged six days through to
13 years and Hoellering et al (2008) studied 30 term and preterm non-muscle relaxed infants undergoing both standard (CMV), and high frequency oscillation ventilation (HFOV). The loss of lung volume between patients suctioned with open and closed methods was significant in both these studies, with 20% loss of measured Expired Tidal Volume (ETV) in compliant patients suctioned using closed suction, as compared to 40% loss for patients suctioned using the open method. This ‘gap’ between maintenance of tidal volume was worse in non-compliant children who required high Positive End Expiratory Pressure (PEEP) and high Peak Inspiratory Pressure (PIP) in order to maintain oxygenation. The open suction group fell as low as 65% loss of ETV, whilst the closed suction group were maintained at only 20% loss. There is a clear indication here that children who require high levels of PEEP and PIP in order to maintain oxygenation will benefit from the application of a closed suction method. Obvious weaknesses of both these studies are that the groups
studied were small in number and diverse in age. Furthermore, it is impossible to guarantee the same ‘level’ of lung injury in human subjects. The contribution of animal studies in this area cannot be ignored. Tingay et al’s study (2010) studied the effect of catheter size and suction pressure on ventilated (CMV and HFOV) neonatal piglets with induced lung injuries. This extensive study strongly suggested that the ETV loss from closed suction methods could be further reduced through the use of small suction catheters. It is therefore vital, both in terms of reducing the risk of systemic de-recruitment of alveoli, and in terms of reducing the risk of zonal atelectasis that the smallest possible size catheter be used. The decision on catheter size is, though, of course also related
to the effective recovery of secretions. This has been a controversial area for a significant period of time. As long ago as 1991, Witmer et al suggested that there was no difference in terms of recovery of secretions between open and closed suction but more recently it has been suggested that the closed method is less effective in recovering secretions. Copnell et al’s study (2007) tested the effectiveness of open and closed techniques in terms of recovery of mucoid and watery secretions in animal models. Their findings are significant for bedside practitioners as it was discovered that particularly with mucoid secretions the difference in the amount of material recovered from the lung was significantly larger with open suction. The reason for this seems to be related to the ‘efflux’ of material that is pulled into the range of the suction catheter when the patient is removed from the ventilator in open suction. In simple terms a constant in-flow of
050 ARAB HEALTH MAGAZINE ISSUE 2 2012
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