viernes, 14 de marzo de 2014

Ventilación en UCI/NAVA

Efectos de NAVA en pacientes con ventilación no invasiva


Effects of Neurally Adjusted Ventilatory Assist (NAVA) levels in non-invasive ventilated patients: titrating NAVA levels with electric diaphragmatic activity and tidal volume matching.
Chiew YS, Chase JG, Lambermont B, Roeseler J, Pretty C, Bialais E, Sottiaux T, Desaive T.
Biomed Eng Online. 2013 Jul 2;12:61. doi: 10.1186/1475-925X-12-61.
Abstract
BACKGROUND:Neurally adjusted ventilatory assist (NAVA) delivers pressure in proportion to diaphragm electrical activity (Eadi). However, each patient responds differently to NAVA levels. This study aims to examine the matching between tidal volume (Vt) and patients' inspiratory demand (Eadi), and to investigate patient-specific response to various NAVA levels in non-invasively ventilated patients. METHODS:12 patients were ventilated non-invasively with NAVA using three different NAVA levels. NAVA100 was set according to the manufacturer's recommendation to have similar peak airway pressure as during pressure support. NAVA level was then adjusted ±50% (NAVA50, NAVA150). Airway pressure, flow and Eadi were recorded for 15 minutes at each NAVA level. The matching of Vt and integral of Eadi (ʃEadi) were assessed at the different NAVA levels. A metric, Range90, was defined as the 5-95% range of Vt/ʃEadi ratio to assess matching for each NAVA level. Smaller Range90 values indicated better matching of supply to demand. RESULTS: Patients ventilated at NAVA50 had the lowest Range90 with median 25.6 uVs/ml [Interquartile range (IQR): 15.4-70.4], suggesting that, globally, NAVA50 provided better matching between ʃEadi and Vt than NAVA100 and NAVA150. However, on a per-patient basis, 4 patients had the lowest Range90 values in NAVA100, 1 patient at NAVA150 and 7 patients at NAVA50. Robust coefficient of variation for ʃEadi and Vt were not different between NAVA levels. CONCLUSIONS: The patient-specific matching between ʃEadi and Vt was variable, indicating that to obtain the best possible matching, NAVA level setting should be patient specific. The Range90 concept presented to evaluate Vt/ʃEadi is a physiologic metric that could help in individual titration of NAVA level.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707774/pdf/1475-925X-12-61.pdf





Revisión clínica: actualización sobre ventilación asistida ajustada neuralmente. Informe de una conferencia de mesa redonda

Clinical review: Update on neurally adjusted ventilatory assist - report of a round-table conference.
Terzi N, Piquilloud L, Rozé H, Mercat A, Lofaso F, Delisle S, Jolliet P, Sottiaux T, Tassaux D, Roesler J, Demoule A, Jaber S, Mancebo J, Brochard L, Richard JC.
Crit Care. 2012 Jun 20;16(3):225. [Epub ahead of print]
Abstract
ABSTRACT: Conventional mechanical ventilators rely on pneumatic pressure and flow sensors and controllers to detect breaths. New modes of mechanical ventilation have been developed to better match the assistance delivered by the ventilator to the patient's needs. Among these modes, neurally adjusted ventilatory assist (NAVA) delivers a pressure that is directly proportional to the integral of the electrical activity of the diaphragm recorded continuously through an esophageal probe. In clinical settings, NAVA has been chiefly compared with pressure-support ventilation, one of the most popular modes used during the weaning phase, which delivers a constant pressure from breath to breath. Comparisons with proportional-assist ventilation, which has numerous similarities, are lacking. Because of the constant level of assistance, pressure-support ventilation reduces the natural variability of the breathing pattern and can be associated with asynchrony and/or overinflation. The ability of NAVA to circumvent these limitations has been addressed in clinical studies and is discussed in this report. Although the underlying concept is fascinating, several important questions regarding the clinical applications of NAVA remain unanswered. Among these questions, determining the optimal NAVA settings according to the patient's ventilatory needs and/or acceptable level of work of breathing is a key issue. In this report, based on an investigator-initiated round table, we review the most recent literature on this topic and discuss the theoretical advantages and disadvantages of NAVA compared with other modes, as well as the risks and limitations of NAVA.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3580602/pdf/cc11297.pdf


Apoyo respiratorio con ventilación asistida neuralmente ajustada en bronquiolitis severa
Respiratory support by neurally adjusted ventilatory assist (NAVA) in severe RSV-related bronchiolitis: a case series report.
Liet JM, Dejode JM, Joram N, Gaillard-Le Roux B, Bétrémieux P, Rozé JC.
BMC Pediatr. 2011 Oct 20;11:92. doi: 10.1186/1471-2431-11-92.
Abstract
BACKGROUND: Neurally adjusted ventilatory assist (NAVA) is a new mode of mechanical ventilation controlled by diaphragmatic electrical signals. The electrical signals allow synchronization of ventilation to spontaneous breathing efforts of a child, as well as permitting pressure assistance proportional to the electrical signal. NAVA provides equally fine synchronization of respiratory support and pressure assistance varying with the needs of the child. NAVA has mainly been studied in children who underwent cardiac surgery during the period of weaning from a respirator. CASE PRESENTATION: We report here a series of 3 children (1 month, 3 years, and 28 days old) with severe respiratory distress due to RSV-related bronchiolitis requiring invasive mechanical ventilation with a high level of oxygen (FiO2 ≥ 50%) for whom NAVA facilitated respiratory support. One of these children had diagnosis criteria for acute lung injury, another for acute respiratory distress syndrome.Establishment of NAVA provided synchronization of mechanical ventilatory support with the breathing efforts of the children. Respiratory rate and inspiratory pressure became extremely variable, varying at each cycle, while children were breathing easily and smoothly. All three children demonstrated less oxygen requirements after introducing NAVA (57 ± 6% to 42 ± 18%). This improvement was observed while peak airway pressure decreased (28 ± 3 to 15 ± 5 cm H2O). In one child, NAVA facilitated the management of acute respiratory distress syndrome with extensive subcutaneous emphysema. CONCLUSIONS: Our findings highlight the feasibility and benefit of NAVA in children with severe RSV-related bronchiolitis. NAVA provides a less aggressive ventilation requiring lower inspiratory pressures with good results for oxygenation and more comfort for the children.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3207882/pdf/1471-2431-11-92.pdf

Atentamente

Dr. Juan C. Flores-Carrillo
Anestesiología y Medicina del Dolor
www.anestesia-dolor.org

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