title: Evaluation of the catheter positioning for neurally adjusted ventilatory assist.
abstract: OBJECTIVE
  During neurally adjusted ventilatory assist (NAVA) the ventilator is driven by the patients electrical activation of the diaphragm (EAdi), detected by a special esophageal catheter. A reliable positioning of the EAdi-catheter is mandatory to trace a representative EAdi signal. We aimed to determine whether a formula that is based on the measurement from nose to ear lobe to xiphoid process of the sternum (NEX distance) modified for EAdi-catheter placement (NEX(mod)) is sufficient for predicting the accurate catheter position.
  
  
  METHODS
  Twenty-six patients were enrolled in this study. The optimal EAdi-catheter position (OPT) was defined by: (1) stable EAdi signal, (2) electrical activity highlighted in central leads of the catheter positioning tool, and (3) absence of p-wave in distal lead. Afterwards NEX(mod) was calculated and compared to the OPT finding.
  
  
  RESULTS
  At NEX(mod) the EAdi signal was suitable for running NAVA in 18 out of 25 patients (72%). NEX(mod) was identical with OPT in four patients (16%). NAVA was possible in all patients at OPT. Median OPT position was 2 cm caudal of the NEX(mod) ranging from 3 cm too cranial to a position 12 cm too caudal (P < 0.01). In one patient excluded from further analysis EAdi-catheter placement led to the diagnosis of bilateral injury of the phrenic nerves.
  
  
  CONCLUSIONS
  EAdi-catheter placement based on the NEX(mod) formula allows running NAVA in about two-thirds of all patients. The additional tools provided are efficient and facilitate the correct positioning of the EAdi-catheter for neurally adjusted ventilatory assist.
authors: Department of Anaesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
authors: Jürgen
authors: J
authors: Barwing
authors: Markus
authors: M
authors: Ambold
authors: Nadine
authors: N
authors: Linden
authors: Michael
authors: M
authors: Quintel
authors: Onnen
authors: O
authors: Moerer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002404:Catheterization / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods*