title: Chest drainage suction decreases differential pleural pressure after upper lobectomy and has no effect after lower lobectomy.
abstract: OBJECTIVE
  To our knowledge, no reports have been published describing the effect of suction on pleural pressures after different types of lobectomy. Improving knowledge of pleural physiology in the postoperative period could lead to better postoperative care. The aim of this investigation is to evaluate the effect of postoperative suction on inspiratory, expiratory and differential pleural pressures after upper or lower lobectomy.
  
  
  METHODS
  Records of intrapleural pressures from 24 lobectomy patients (operated on in two different institutions) were selected for study. All patients had normal preoperative pulmonary function tests (forced expiratory volume in 1s (FEV1) >80% and forced vital capacity (FVC)/FEV1 >70%), and neither postoperative air leak nor any other postoperative complication. We selected six cases of each type of lobectomy (right upper lobectomy (RUL), right lower lobectomy (RLL), left upper lobectomy (LUL) and left lower lobectomy (LLL)). In three cases of each group, no suction was indicated, while in the other three cases, chest tubes were placed under 15 cm H(2)O suction, according to the standard local perioperative care protocol in each participating centre. Inspiratory and expiratory pleural pressures were measured at 2-min intervals by an electronic device using a DigiVent (Millicore A.B., Sweden) suction chamber. Recording started 5-10h after closing the chest, and included 5 consecutive hours during the first postoperative night, with the patients at rest in 30-45 degrees sitting position. There was no evidence of pneumothorax during the recording time. The influence of lobectomy site (upper or lower) and suction on inspiratory, expiratory and differential pressures were evaluated by Student's t-tests.
  
  
  RESULTS
  In the group of cases under no suction, upper lobectomy patients had larger differential pressures (22.6 in upper vs 11.5 cm H(2)O in lower lobectomy cases, p<0.001), differential pressure decreased in patients under suction (9.1 in upper vs 11.1 cm H(2)O in lower lobectomy cases, p<0.001) and the effect was mainly due to a less negative inspiratory pressure.
  
  
  CONCLUSIONS
  Pleural suction leads to a large decrease of differential pleural pressure after upper pulmonary lobectomy. The influence of this finding on postoperative work of breathing in the early postoperative period remains to be investigated.
authors.affiliation: Service of Thoracic Surgery, Salamanca University Hospital, Salamanca, Spain. gvs@usal.es
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Varela
authors.forename: Alessandro
authors.initials: A
authors.lastname: Brunelli
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: Jiménez
authors.forename: Luca
authors.initials: L
authors.lastname: Di Nunzio
authors.forename: Nuria
authors.initials: N
authors.lastname: Novoa
authors.forename: José L
authors.initials: JL
authors.lastname: Aranda
authors.forename: Armando
authors.initials: A
authors.lastname: Sabbatini
mesh_terms: D015505:Chest Tubes; D045853:Exhalation / Q000502:physiology; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D001239:Inhalation / Q000502:physiology; D010994:Pleura / Q000503:physiopathology*; D011013:Pneumonectomy / Q000379:methods*; D011182:Postoperative Care / Q000379:methods*; D011312:Pressure; D013396:Suction; D014797:Vital Capacity / Q000502:physiology