Allen BS, Shaikh R, Ilbawi MN, Kronon M, Bolling KS, Halldorsson AO, Feinberg H: Detrimental effects of cardiopulmonary bypass in cyanotic infants: preventing the reoxygenation injury. Ann Thor Surg 64: 1381-1388,1997.

Brief Summary:

This study was undertaken to determine the potential for hypoxia/reoxygenation injury to occur in chronically hypoxic neonates undergoing bypass and to elucidate the effect of either slow onset reoxygenation and/or leukocyte reduction filtration technology to blunt the injury. The response measure employed was an assessment of anti-oxidant reserve capacity of biopsied heart muscle as a surrogate marker of the potential for injury to this tissue.

The results suggest that infants manifesting chronic hypoxia with exposure to bypass surgery are at risk for myocardial hypoxia/reoxygenation injury. This injury may be blunted by initiating bypass at low oxygen partial pressures and slowly increasing the levels of oxygen as the case proceeds. Using leukocyte reducing filters for blood added to the circuit as well as during the bypass procedure provides substantially more oxidation reserve capacity than does reducing oxygen alone. The combination, however, provides the best protection to the heart of the cyanotic infant.

The authors conclude by saying: "In summary, our study findings support those of previous investigations and show that cyanotic infants are predisposed to generation of large quantities of oxygen free radicals in response to the initiation of cardiopulmonary bypass [references]. However, oxygen free radical production can be limited by decreasing the oxygen concentration of the bypass circuit or, more effectively, by leukocyte filtration."

RA van Lingen, W Baerts, A Marquering, GJHM Ruijs. ELD96 particle filters in sick newborn infants result in significantly fewer infectious complications at lower cost. Journal of Clinical Microbiology and Infection 1997;3:122.

Brief Summary:

This study was presented at the 8th European Congress of Microbiology and Infectious Diseases, held in Lausanne, Switzerland, in May 1997. The authors compared the rates of infection and other major complications in patients receiving infusions with or without endotoxin-retentive filtration. The cost of disposable infusion equipment and nursing time required to change it were also compared between the two groups. Use of this filter reduced infection rates and lowered costs.

Methods:

88 newborn infants (76 preterm, 12 term), were randomised to receive IV fluids and medications through an endotoxin-retentive intravenous filter (Pall Posidyne ELD96) or unfiltered. In the filter group all medications and fluids except lipids, blood and blood products were filtered, and sets and filters were changed every four days. Sets were changed daily in the control group. Used filters and IV catheters, IV fluids, blood and tracheal aspirate were cultured. Phlebitis, extravasation, necrosis, thrombosis, and septicaemia were scored. Costs of infusion disposables and nursing time were monitored.

Results:

Total complications were reduced in the filter group, (9 cases versus 19). This reflected a 50% reduction in sepsis (4 cases Vs 8). The mean cost of disposables was reduced from DFl 68.64 in the control group to DFl 52.41 in the filter group. When the cost of nursing time was estimated the overall costs were reduced from DFl 188.68 in the control group to DFl 82.41 in the filter group.

Conclusions:

The authors concluded that the use of a Posidyne ELD 96 hour filter leads to significant decreases in major complications, the cost of disposables and the nursing time required to change them.

R Robinson & P Ball. Does the Pall TNA1E parenteral nutrition admixture filter retain Malassezia furfur? Nutrition 1998;14:363-365.

Brief Summary:

This paper demonstrates that the Pall Lipipor TNA 1.2µm filter for lipid-containing parenteral nutrition reliably retains the neonatal fungal pathogen Malassezia furfur.

Methods:

M. furfur was isolated from the skin of adult volunteers and inoculated into intravenous lipid emulsion. This was filtered through the test device at 2mL/hour to simulate a typical infusion regime used in a neonatal unit, and the filtrate cultured. Unfiltered controls were also cultured. Results: No growth was found in the filtrate, unfiltered controls were found to be positive for M. furfur.

Conclusion:

The authors concluded that the Pall TNA filter reliabily retained M.furfur.

JP Monrigal, JC Granry. The benefit of using a heat and moisture exchanger during short operations in young children. Paediatric Anaesthesia 1997;7: 295-300.

Brief Summary:

In pediatric anesthesia, heat and moisture conservation is very important. The use of a small volume heat and moisture exchanging filter can prevent loss of body heat. Such a device providing effective filtration can also prevention cross infection, where anesthetic equipment is used on several consecutive patients. This paper describes the use of the Pall BB25 breathing system filter in paediatric anaesthesia.

Methods:

Forty children in the age range one to nine years, body weight 9.5 - 21kg, undergoing routine urological or abdominal surgery, were randomised to the filter or control group. Halothane was used for induction of anaesthesia, maintenance was with isoflurane, halothane or propofol. Fentanyl was used for analgesia and atracurium was used where muscle relaxation was required for intubation in older children. Uncuffed tracheal tubes were used for intubation and the length of tube protruding from the mouth was recorded. Controlled mode ventilation was used.

Operating room temperature was recorded. Patients were placed supine on a heated mattress and body temperature was recorded using a rectal probe. Frequency of ventilation, tidal volume, peak inflation pressure and respiratory leak were all monitored. Sidestream capnography was used to monitor end-tidal CO₂ connected to the filter port, or to the tracheal tube in the control group. Relative and absolute humidity and temperature of the anaesthetic gases were monitored.

Results:

The authors found no difference in ventilator parameters, including no deleterious effect on effective deadspace in the ventilator circuit. The use of the filter increased the temperature and humidity of the anaesthetic gas very rapidly, from the dry anaesthetic gas level of 19°C and 0.16mg H₂O to 27.5°C and 22.3mg H₂O, within the first minute of the procedure. Samples taken from the Y-piece show constant, significant, differences between the filter and control group, throughout the operating time:

Conclusions:

The authors note that there is no clear definition of optimal humidification in the airway, especially in paediatrics. However the values they measured in the filter group were always higher than the level of 20mg H₂O/litre commonly quoted as the threshold for prevention of damage to the airway epithelium.

They conclude:

"To maintain homeostasis as closely as possible, the introduction of a heat and moisture exchanging filter into the circuit is justified by the constant and immediate increase in humidity and temperature produced at the airway level, even for anaesthesia of short duration."