[Evaluation of amplified spontaneous pattern ventilation in postoperative patients. Comparison with pressure support].
OBJECTIVE
Amplified spontaneous pattern (ASP) ventilation is a new method for giving partial support by reproducing, in an amplified manner, the patients' own spontaneous flow wave form, thereby optimizing patient adaptation to support.


OBJECTIVE
To study clinical use of ASP ventilation for the first time in terms of flow wave form, patient synchronization, ventilation pattern, work of breathing (WOB), and inspiratory effort by transpulmonary pressure (TPP) and to compare ASP and pressure support ventilation applied in a similar clinical setting.


METHODS
We studied 20 patients after heart surgery during weaning from controlled ventilation. Each patient was ventilated during 4 phases of 15 min each with two similar levels of support using ASP and PS applied successively and randomly. Maximum support (ASPmax and PSmax) was that which was set to give the same respiratory frequency (F) and tidal volume (VT) as that recorded during the earlier period of controlled ventilation. Half support (PEA1/2 and PS1/2) was set for half the aforementioned levels. At the end of each phase we obtained gas measurements and flow (V) curves and VT and pressure in airways and esophagus (Pes) to measure F, VT, the ratio of inspiratory to total time (TI/TTOT and TPP, as well as the VT/Pes loop with a mechanical ventilation monitor. The WOB was determined by measuring area under the curve (Campbell's method).


RESULTS
We observed no significant differences between the two modes, with similar levels of support, with regard to ventilation (PaCO2) or ventilatory pattern (F, VT, TI/TTOT). De-adaptation occurred, however, eight times with PS (25%) but never with ASP. WOB and TPP decreased with PS when level of support increased, whereas with ASP these variables were constant regardless of level of amplification within the normal range.


CONCLUSIONS
Adaptation to support is better with ASP than with PS during postoperative weaning and causes no significant respiratory work overload.
Sánchez de Merás
A M
AM
Servicio de Anestesiología y Reanimación, Hospital Clínico Universitario de Valencia.
Páiz
P
P
Perpiñán
I
I
García Polit
J
J
Soliveres
J
J
Aguilar
G
G
Maruenda
A
A
Belda
F J
FJ
D000222:Adaptation, Physiological; D002245:Carbon Dioxide / Q000097:blood; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics; D006801:Humans; D009204:Myocardial Revascularization; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011182:Postoperative Care / Q000379:methods*; D011183:Postoperative Complications / Q000503:physiopathology / Q000628:therapy; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D012120:Respiration Disorders / Q000503:physiopathology / Q000628:therapy; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology; D012138:Respiratory Therapy / Q000379:methods*; D015300:Ventilator Weaning; D014939:Work of Breathing
D002245:Carbon Dioxide; D010100:Oxygen
Evaluación de la ventilación con patrón espontáneo amplificado en pacientes postoperados. Comparación con la presión de soporte.