Mechanical Power in Pediatric Mechanical Ventilation
Condition: Mechanical Ventilation Complication; Aediatric Anesthesia
Study type: Observational

Summary: 
      Mechanical power is the amount of energy transferred to the respiratory system of patients
      during each breath period. After overcoming the resistances required for respiration, the
      remaining energy may end up by damaging the lung parenchyma. Promising studies are showing
      that this amount of energy, which can be calculated mathematically, can be used as a single
      indicator instead of the limits used for barotrauma, volu-trauma, or atelecto-trauma in adult
      patients. However, the MP limit that should not be exceeded in pediatric patients is not yet
      clear. In this study, we present our MP calculations in pediatric anesthesia
    

Detailed description: 
      Mechanical ventilation is applied to millions of healthy and sick lungs every year in
      perioperative conditions and intensive care units. Meanwhile, the energy applied to the lungs
      by the ventilator during mechanical ventilation is usually used to overcome resistance in the
      chest wall and airways. Leftover energy is consumed by temperature, inflammation, and
      potentially lung tissue damage (1). The risk of ventilation-related damage increases in lungs
      with impaired homogeneity and ventilation-perfusion imbalance (1). As demonstrated by
      experimental and clinical studies, mechanical ventilation-induced lung injury (VILI) is
      associated with tidal volume, peak pressure, respiratory rate, and airflow. The physical
      force applied during ventilation TV increases exponentially with driving pressures (ΔPaw),
      flow (exponent = 2), and respiration rate (RR) (exponent = 1.4), and linearly with positive
      end-expiratory pressure (PEEP) (2). When the effects of these parameters are formulated, the
      energy applied to the lungs is revealed. This energy has been formulated as Joule/minute and
      has now taken its place as mechanical power (MP) in the literature. (2). A benefit of the MP
      calculation is that it is a single, easily calculated indicator parameter that can be used
      for the risks of barotrauma, volutrauma, or atelectotrauma associated with VILI. As shown in
      different publications, high MP values were associated with negative outcomes such as
      increased 30-day mortality in intensive care patients, increased length of stay in hospital
      and intensive care unit, and decreased number of ventilator-free days(3)(4). Cressoni et al.
      showed in their experimental study that MP values above 12 J/min in healthy pigs are
      associated with MV-related complications and this value can also be used as an alarm limit in
      humans(5). In addition, Costa et al found that 0.32 ± 0.14 J / min/ kg indexed MP(MP/Kg) was
      associated with increased mortality in ARDS patients(6). Some recent studies also support the
      conclusion that Mp calculation is beneficial(7)(8). For this reason, Gattinoni et al.
      suggests that MP limits and formula should be added to the mechanical ventilator software(2).
      However, studies on MP have often focused on ARDS and have been performed on intensive care
      patients or experimental animal models(9). Although MP is a promising safety limit with its
      easy computability, there are still questions about the formula and its usefulness. The
      success of the MP formula in perioperative situations and especially in pediatric patients
      has not been adequately tested. As far as we know, our study is one of the first publications
      to question the MP threshold in healthy pediatric cases.

      In this study, our primary aim is to calculate the MP applied in pediatric cases who will
      undergo inguinal hernia surgery under general anesthesia.

      Our other aims are the calculation of the mechanical power applied per kilogram and the other
      transferred energies, their comparison with the literature, and questioning the possible
      contribution of a mechanical power formula to safe mechanical ventilation in pediatric cases.
    

Intervention name(s): Mechanical power
Intervention type(s): Diagnostic Test
Intervention description(s): In our study, mechanical power (MP) will be calculated during mechanical ventilation in patients who will be operated under general anesthesia.
MP will be calculated with the simplified formula applied by Gattinoni et al. MPvcv: RR x Tv x (PIP-[(Pplat-PEEP)/2]) x 0.098(2) In pressure-controlled ventilation, the simplified MP formula of Becher et al. well be used.
MPpcv: RR x Tv x (ΔPinsp + PEEP) x 0.098 (11)
For MP calculated according to the weight of the patients; Indexed MP: MP /kg according to IBW. For the force applied to the lungs in each inspiration; Dynamic power (mJ/min): Vt x RR x [(Pplato+ tPEEP)/2]. For the driver power that provides the gas flow; Driving power (mJ/min): Vt x RR x [ (Pplat - tPEEP) / 2]. Calculating mechanical energy; Mechanical energy (mJ/kg): 0.098 x (V x kg ) x (PIP - [(P plateau- PEEP) / 2]) formulas were used
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All patients under the age of 18 who will undergo laparoscopic lower abdomen surgery under
        general anesthesia under elective conditions.
      
Keywords: mechanical ventilation; pediatric anesthesia; mechanical power