Cardiorespiratory responses to negative pressure ventilation after tetralogy of Fallot repair: a hemodynamic tool for patients with a low-output state
Lara S. Shekerdemian, MD, MRCPa,
Andrew Bush, MD, FRCPa,
Darryl F. Shore, FRCS*,
Christopher Lincoln, FRCSa and
Andrew N. Redington, MD, FRCPa
a Department of Pediatrics, Royal Brompton Hospital, London, England, United Kingdom
* Department of Surgery, Royal Brompton Hospital, London, England, United Kingdom
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Figure 1 Change in Qp for all patients during a standard study. The overall mean increase in pulmonary blood flow during negative pressure ventilation was 38.8%.
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Figure 2 Extended studies: sub-group 1. The Qp of these nine patients increased by 40% during a standard study, but then returned towards baseline 15 min after re-instituting positive pressure ventilation (IPPV2). This would suggest that the duration of hemodynamic benefit of NPV at this early stage did not exceed the period of its use.
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Figure 3 (A) Extended studies: sub-group 2. Qp increased by 21% during a standard study (NPV1), and then increased by a further 38% during when the period of negative pressure ventilation was extended by 20 to 30 min (NPV2). The total increase in Qp was 67%. (B) Sub-group 2: restrictive versus nonrestrictive patients. The initial increase in Qp was lower during a standard study (1) for restrictive patients (19%), than nonrestrictive patients (26%). When the period of negative pressure ventilation was further extended (2), the increase was higher for restrictive patients (54%) than nonrestrictives (20%), and the total increase at the end of the study period (3) was 67%.
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