Effects on Respiratory Mechanics of Two Different Ventilation Strategies During Robotic-Gynecological Surgery
Phase: NA
Conditions: Respiratory Mechanics, Mechanical Ventilation Complication
Sponsor: SPINAZZOLA GIORGIA

Protocol ID 10398/14 
 
Effects on Respiratory mechanics of two different ventilation strategies during 
roboticgynecological surgery. 
  
Introduction:  
For many years, the mechanical ventilation during general anesthesia has been conducted using 
high tidal volumes (Vt) and without applying Positive End Expiratory Pressure (PEEP). This 
ventilatory strategy was considered to avoid alveolar collapse to improve ventilationperfusion 
mismatch and to reduce the oxygen fraction. The potential harmful effects of short term intra-
operative ventilation are increasingly recognized [1]. The mechanical ventilation may cause a 
pulmonary complication defined Ventilator-Induced Lung Injury (VILI). This respiratory condition 
is characterized by alveoli overdistension or repetitive opening and closing of atelectasic lung area.  
Alveolar overdistension could be prevented applying lower Vt [2] and higher levels of PEEP could 
prevent alveolar derecruitment [3]. Recently, two conventional meta-analyses of observational 
studies and randomized controlled trials on intra-operative ventilation have supported the use of 
lung protective ventilation, with lower Vt and higher levels of PEEP in order to prevent VILI and 
postoperative pulmonary complications [4,5]. Further studies are necessary to understand if the 
outcome improvement was related to lower Vt  or high levels of PEEP. Laparoscopy is a well-
established procedure for gynecologic surgery, with an induced pneumoperitoneum to facilitate the 
laparoscopic manipulation and it is often performed in Trendelemburg position (the head down 
body position). The increase of abdominal pressure related to both pneumoperitoneum and 
Trendelemburg position has demonstrated to impair the respiratory function, mainly inducing 
atelectasis area in the dependent lung regions [6-9]. In case of atelecasis, the distribution of Vt to 
the limited amount of functional lung parenchyma may induce alveolar stress and strain. These 
conditions are the main mechanisms underlying VILI [10-11] and the hypothesis that a protective 
ventilation has some benefits and should be applied during general anesthesia has been widely 
demonstrated [ 6,9,12-15]. Recently, the concept of “lung protective ventilation strategy” has been 
adapted from acute respiratory distress syndrome to the anesthesiologic management. In fact, the 
application of an “open lung” strategy, consisting in a recruitment maneuvers (RMs) followed by 
the consequent application of PEEP has been suggested to be able to improve oxygenation through  
the re-expantion of penumoperitoneum-induced atelectasis area. The effects of open lung 

ventilatory strategy on respiratory mechanics and postoperative pulmonary complications in healthy 
patients underwent robotic–laparoscopic surgery in deep Trendelemburg position have not been 
specifically investigated. The aim of this study was to evaluate the effects of two ventilatory 
strategies (protective mechanical ventilation versus conventional mechanical ventilation), during 
general anesthesia in robotic laparoscopic gynecological surgery in deep Trendelemburg position, 
on respiratory mechanics and postoperative pulmonary complications in healthy patients.  
  
Methods:  
The ventilation protocol consisted in volume-controlled mechanical ventilation thought Servo I 
Ventilator, inspiratory to expiratory ratio of 1:2, and a respiratory rate adjusted to normocapnia 
(end-tidal carbon dioxide partial pressure between 30 and 40 mmHg). Patients were randomly 
assigned to Standard (SV) or Protective (PV) group. Patients in the SV group received a Vt of 10 
ml/kg of Ideal Body Weight (IBW) and a PEEP of 5 cmH2O, patients in the PV group a Vt of 6 
ml/kg of IBW and a PEEP of 8-10 cmH2O, associated to recruitment maneuvers (RMs). IBW was 
calculated according to a predefined formula: 50 + 0,91(height [cm] −152,4) for men and 45,5 + 
0,91 (height [cm]−152,4) for women [16]. RMs were performed only in hemodynamic stable 
conditions and at pre-set moments: after the induction of anesthesia, after any disconnection from 
the mechanical ventilator, each hour during the surgical procedures and immediately before 
extubation. RMs were performed in Pressure Control mode as follows: the limit of peak inspiratory 
pressure was set at 45 cmH2O and the pressure control was set at 30 cmH2O, therefore three 
consecutive thirty seconds lasting inspiratory pauses were performed.  At the end of RMs, 
respiratory rate, inspiratory to expiratory ratio, inspiratory pause, and Vt were set back at values 
preceding the RMs.  
  
  
  
  
Statistical Analysis: 
 All data are expressed as mean ± standard deviation (DS).  We use the 2 –side T tests to compare 
the respiratory variables and gas exchange between the two groups tested. The analysis of variance 
for repeated measures in each group was performed by one-way ANOVA. When detected, post hoc 

analysis was performed using Bonferroni Test. P values ≤ 0,05 were considered statistically 
significant.  
  
  
  
  
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