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Page 6 of 12 Echeverria-Villalobos et al. Vessel Plus 2019;3:33 I http://dx.doi.org/10.20517/2574-1209.2019.12

In addition to direct nerve injury (i.e., neuropraxia), the LIMA retractor has been also associated
with lesion of the left internal oblique abdominal, external oblique abdominal and rectus abdominis
muscles [35,38,39] . In contrast, sternotomy with intact pleura maintains respiratory system and chest wall
elastance unchanged. However, the opening of the parietal pleura leads to lung collapse with decreased
[32]
lung elastance and resistance . In addition, the use of LIMA for grafting requires the insertion of a
pleural subxyphoid or left intercostal tube for drainage, being subxyphoid placement associated with lesser
impairment and postoperative pain when compared to intercostal insertion [33,40,41] .

Blood transfusion
Blood transfusion is used in 30%-60% of patients undergoing cardiac surgery and the reported incidence
of transfusion-related acute lung injury (TRALI) is 2.5% [42-44] . Blood transfusion has been linked to
[45]
an increased risk of postoperative morbid events , being transfusion of > 3 red blood cells units an
[46]
independent risk factor for increased hospital LOS after cardiac surgery . Presence of bioactive lipids and
antibodies in the stored blood, and the activation of transfused neutrophils in the setting of an exacerbated
host’s systemic and pulmonary inflammatory response are some of the mechanisms involved in the
[47]
TRALI .
Cardiotomy for suction
Tissue plasminogen activating factor, pro-inflammatory mediators (i.e., cytokines, activated leukocytes,
lipids), pro-coagulants, and platelet factors are present in the cardiotomy suction blood. Numerous reports
have shown the detrimental effects associated with these mediators during re-transfusion of unwashed
blood collected in the pericardium including an increased inflammatory response with impaired lung
function and hemostasis [48,49] . Cell savage devices helps to remove these activated mediators from the blood
obtained from cardiotomy suction [50,51] .

Extracorporeal circulation
In spite of innovations in biocompatibility of CPB circuit’s surfaces, the inflammatory response associated to
extracorporeal circulation with subsequent anti-inflammatory response as well as the ischemia-reperfusion
injury, continue to have a significant impact on postoperative morbidity and mortality after cardiac
[52]
surgery . The exposure of plasma proteases to CPB circuit’s non-endothelial surface (“contact activation”)
immediately activates the complement pathways and factor XII (XIIa). Likewise, classic complement
pathway is activated by heparin-protamine complexes, coagulation and fibrinolysis byproducts (from the
activation of the extrinsic coagulation pathway after vascular injury). Activation of classical and alternative
pathway promotes the release of pro-inflammatory cytokines (TNFα, IL-1, IL-2, and IL-8), production of
activated-polymorphonuclear leukocytes, endothelial cell damage, and capillary permeability [21,52-54] . The
combination of the aforementioned factors along with ischemia-reperfusion injury results in endothelial,
[21]
alveolar and interstitial edema, increased airway resistance and atelectasis . Moreover, hemodilution
[55]
(required to prevent embolism and hemolysis during CPB) may exacerbate pulmonary edema .
Cessation of ventilation and altered surfactant production and function
Type II alveolar cell dysfunction, inactivation of large aggregate by alveolar edema fluid, and/or large
aggregate leakage across the damaged alveolar capillary membrane are some of the effects of apnea and
lung collapse to FRC during CPB, being the inflammatory response triggered by the use of a foreign bypass
[56]
circuit during extracorporeal circulation . These biochemical and functional disturbances significantly
affect surfactant concentration and functionality, contributing to the onset of atelectasis. Cyclic alveoli
stretch is necessary to produce a signal transduction responsible of stimulating surfactant secretion by
Type II alveolar cell [57-59] . Therefore, apnea during CPB may significantly reduce surfactant secretion.
[60]
Govender et al. reported that patients who underwent off-pump coronary bypass with MV using
PEEP experienced higher postoperative large aggregate concentrations when compared to patients who