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Patient-triggered ventilation of neonates
Sir—Roger Soll (July 8, p 90)1 takes a dim but, we feel, unfounded view of neonatal patient-triggered ventilation (PTV). Although his recommendation that the technique should be refined is reasonable, his alternative, that is PTV should be abandoned, is not. Soll’s argument is reminiscent of the commentary that arose after the initial HIFI study, which had a negative impact on the development of highfrequency oscillation and underscores the pitfalls of basing conclusions on a meta-analysis in which one large trial with contrary results unduly affects the outcome. J Baumer and co-workers2 recruited 924 infants into their trial and reported no positive effect of PTV. Yet we and others have shown significant short-term benefits, including shortened duration of mechanical ventilation, less use of sedatives, fewer complications, and lower costs of care. Thus, the negative results of Baumer’s study and another large trial3 included in Soll’s review are surprising and raise questions as to whether suboptimum PTV delivery in the two studies led to the poor outcomes. We have commented elsewhere4 on Baumer and colleagues’ study but, most importantly, most of the infants in that and all in the Liverpool study3 were exposed to a pressuretriggering device that might be unsuitable for very preterm infants because of the work necessary to exceed the trigger sensitivity. Thus, a more appropriate recommendation for PTV is, as for all other neonatal management strategies, to be confident that the technique has been perfected before starting large randomised trials. PTV is being refined, as evidenced by the development of features such as flow-triggering, expiratory sychronisation, volume guarantee, and volumeassured pressure support.5 Only after the optimum technique and strategy have been identified will the results of a study assessing long-term outcomes be meaningful. Steven Donn, Sunil Sinha, *Anne Greenough Department of Neonatal-Perinatal Medicine, University of Michigan Health System, Ann Arbor, MI, USA; Department of Neonatal Services, South Cleveland Hospital, Middlesbrough, UK; and *Department of Child Health, Guy’s King’s and St Thomas’ School of Medicine, Neonatal Intensive Care, King’s College Hospital, London SE5 9RS, UK (e-mail: [email protected])
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Soll R. Patient-triggered ventilation of the newborn. Lancet 2000; 356: 90–91. Baumer J. International randomized controlled trial of patient triggered ventilation in neonatal respiratory distress syndrome. Arch Dis Child Fetal Neonatal Ed 2000; 82: F5–10. Beresford MW, Shaw NJ, Manning D. Randomized controlled trial of patient triggered and conventional fast ventilation in neonatal respiratory distress syndrome. Arch Dis Child Fetal Neonatal Ed 2000; 82: F14–18. Donn SM, Greenough A, Sinha S. Patient triggered ventilation. Arch Dis Child (in press). Sinha SK, Donn SM. Weaning from assisted ventilation: art of science? Arch Dis Child Fetal Neontal Ed 2000; 83: F64–70.
Author’s reply Sir—Steven Donn and colleagues express an optimistic perspective on the future of PTV. I agree that PTV is an appealing new technology that fully warrants further assessment, especially as we perfect the technical features of delivering this care to the smallest and sickest neonates. Where our opinions diverge is the somewhat simplistic sense that trials should await technological perfection. Ventilators equipped to deliver PTV are currently available for sale in neonatal intensive care units in moredeveloped countries. These ventilators cost substantially more than conventional ventilators. Most neonatal intensive-care units in North America (including my own) have switched to devices capable of delivering PTV. Yet, as Donn and colleagues imply, this technology may not be ready for large-scale trials, let alone standard practice. My concerns arise from the rapid distribution of this or any similar technology before appropriate assessment, not to any theoretical concern about the basis of PTV. As noted in my previous comments, our love affair with technological advances leads to the rapid adoption of technology before the innovations are proven to be worthwhile. It is this costly and potentially dangerous practice of allowing new technology to be used routinely before appropriate assessment that must be curtailed, not the commitment to future research and technical innovation.
Chlamydia pneumoniae IgG seropositivity in deepvein thrombosis Sir—Ted Koster and colleagues (May 13, p 1694)1 show no increased risk for deep-vein thrombosis with raised titres of antibody to Chlamydia pneumoniae with ELISA. We doubt, however, whether this ELISA is the method of choice to assess the relation between C pneumoniae infection and deep-vein thrombosis since no data on detection with this ELISA are available. Most seroepidemiological studies on the relation between C pneumoniae and cardiovascular disease have been done with a microimmunofluorescence (MIF) test.2,3 Also, the study of O Lozinguez and colleagues,4 which showed a positive association between C pneumoniae antibody titres and venous thromboembolism, was done with the MIF test. The negative results of Koster and co-workers might, therefore, be due to the method of antibody detection. We compared the ELISA they used (ELISASeroCP, Ashdod, Israel) with the MIF-test. We took serum samples from 94 patients with vascular disease who visited the internal medicine outpatient clinic at our hospital, and from 122 healthy volunteers. Detection of IgG antibodies to C pneumoniae (TW 183) was done with a validated MIF test (MRL, Cypress, CA, USA)5 and by ELISA-SeroCP. Samples were masked and were prepared and tests were done and interpreted according to the manufacturer’s instructions. The correlation between the antibody titres for the two tests was poor (figure). If we used the proposed cutoff point of 1·1 for ELISA-SeroCP and 1/16 for the MIF test, eight samples were negative in both tests, 154 positive in both tests, 38 positive only in the MIF test, and 600 500 MIF titre
Patient-triggered ventilation of neonates
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Roger F Soll University of Vermont College of Medicine, Medical Alumni Building A-121, Burlington, VT 05405, USA (e-mail: [email protected])
0 0·5 1·0 1·5 2·0 2·5 3·0 3·5 4·0 ELISA-SeroCP cut-off index
Correlation between MIF test and ELISA-SeroCP
THE LANCET • Vol 356 • November 4, 2000
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Soll R. Patient-triggered ventilation of the newborn. Lancet 2000; 356: 90–91. Baumer J. International randomized controlled trial of patient triggered ventilation in neonatal respiratory distress syndrome. Arch Dis Child Fetal Neonatal Ed 2000; 82: F5–10. Beresford MW, Shaw NJ, Manning D. Randomized controlled trial of patient triggered and conventional fast ventilation in neonatal respiratory distress syndrome. Arch Dis Child Fetal Neonatal Ed 2000; 82: F14–18. Donn SM, Greenough A, Sinha S. Patient triggered ventilation. Arch Dis Child (in press). Sinha SK, Donn SM. Weaning from assisted ventilation: art of science? Arch Dis Child Fetal Neontal Ed 2000; 83: F64–70.
Author’s reply Sir—Steven Donn and colleagues express an optimistic perspective on the future of PTV. I agree that PTV is an appealing new technology that fully warrants further assessment, especially as we perfect the technical features of delivering this care to the smallest and sickest neonates. Where our opinions diverge is the somewhat simplistic sense that trials should await technological perfection. Ventilators equipped to deliver PTV are currently available for sale in neonatal intensive care units in moredeveloped countries. These ventilators cost substantially more than conventional ventilators. Most neonatal intensive-care units in North America (including my own) have switched to devices capable of delivering PTV. Yet, as Donn and colleagues imply, this technology may not be ready for large-scale trials, let alone standard practice. My concerns arise from the rapid distribution of this or any similar technology before appropriate assessment, not to any theoretical concern about the basis of PTV. As noted in my previous comments, our love affair with technological advances leads to the rapid adoption of technology before the innovations are proven to be worthwhile. It is this costly and potentially dangerous practice of allowing new technology to be used routinely before appropriate assessment that must be curtailed, not the commitment to future research and technical innovation.
Chlamydia pneumoniae IgG seropositivity in deepvein thrombosis Sir—Ted Koster and colleagues (May 13, p 1694)1 show no increased risk for deep-vein thrombosis with raised titres of antibody to Chlamydia pneumoniae with ELISA. We doubt, however, whether this ELISA is the method of choice to assess the relation between C pneumoniae infection and deep-vein thrombosis since no data on detection with this ELISA are available. Most seroepidemiological studies on the relation between C pneumoniae and cardiovascular disease have been done with a microimmunofluorescence (MIF) test.2,3 Also, the study of O Lozinguez and colleagues,4 which showed a positive association between C pneumoniae antibody titres and venous thromboembolism, was done with the MIF test. The negative results of Koster and co-workers might, therefore, be due to the method of antibody detection. We compared the ELISA they used (ELISASeroCP, Ashdod, Israel) with the MIF-test. We took serum samples from 94 patients with vascular disease who visited the internal medicine outpatient clinic at our hospital, and from 122 healthy volunteers. Detection of IgG antibodies to C pneumoniae (TW 183) was done with a validated MIF test (MRL, Cypress, CA, USA)5 and by ELISA-SeroCP. Samples were masked and were prepared and tests were done and interpreted according to the manufacturer’s instructions. The correlation between the antibody titres for the two tests was poor (figure). If we used the proposed cutoff point of 1·1 for ELISA-SeroCP and 1/16 for the MIF test, eight samples were negative in both tests, 154 positive in both tests, 38 positive only in the MIF test, and 600 500 MIF titre
Patient-triggered ventilation of neonates
400 300 200 100 0
Roger F Soll University of Vermont College of Medicine, Medical Alumni Building A-121, Burlington, VT 05405, USA (e-mail: [email protected])
0 0·5 1·0 1·5 2·0 2·5 3·0 3·5 4·0 ELISA-SeroCP cut-off index
Correlation between MIF test and ELISA-SeroCP
THE LANCET • Vol 356 • November 4, 2000