The Coagulopathy of Acute Type A Aortic Dissection: A Prospective, Observational Study.

OBJECTIVE: To evaluate the hemostatic system in patients undergoing surgery for acute type A aortic dissection (ATAAD) compared with those undergoing elective aortic procedures. DESIGN: This was a prospective, observational study. SETTING: The study was performed at a single university hospital. PARTICIPANTS: Twenty-five patients with ATAAD were compared with 20 control patients undergoing elective surgery of the ascending aorta or the aortic root. INTERVENTIONS: No interventions were performed. MEASUREMENTS AND MAIN RESULTS: Platelet count and levels of fibrinogen, D-dimer, prothrombin time/international normalized ratio, activated partial thromboplastin time, and antithrombin were analyzed perioperatively and compared between the 2 groups. Patients with ATAAD had lower preoperative levels of platelets (188 [156-217] × 109/L v 221 [196-240] × 109/L; p = 0.018), fibrinogen (1.9 [1.6-2.4] g/L v 2.8 [2.2-3.0] g/L; p = 0.003), and antithrombin (0.81 [0.73-0.94] kIU/L v 0.96 [0.92-1.00] kIU/L; p = 0.003) and significantly higher levels of D-dimer (2.9 [1.7-9.7] mg/L v 0.1 [0.1-0.2] mg/L; p < 0.001) and prothrombin time/international normalized ratio (1.15 [1.1-1.2] v 1.0 [0.93-1.0]; p = 0.001). Surgery caused significant changes of the coagulation system in both groups. Intraoperative bleeding volumes were larger in the ATAAD group (2,407 [1,804-3,209] mL v 1,212 [917-1,920] mL; p < 0.001), and patients undergoing ATAAD surgery received significantly more transfusions of red blood cells (2.5 [0.25-4.75] U v 0 [0-2.75] U; p = 0.022), platelets (4 [3.25-6] U v 2 [2-4] U; p = 0.002), and plasma (2 [0-4] U v 0 [0-0] U; p = 0.004) compared with the elective group. CONCLUSIONS: This study demonstrates that ATAAD is associated with a coagulopathic state. Surgery causes additional damage to the hemostatic system in ATAAD patients, but also in patients undergoing elective surgery of the ascending aorta or the aortic root.

Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets.

INTRODUCTION: Non-bronchoscopic bronchoalveolar lavage is an alternative to diagnostic bronchoscopy in pediatric patients, as fiberoptic bronchoscopes with aspiration channels are too large for small infants. There are many variations of the method in clinical practice, and saline instillation followed by open endotracheal suctioning is still commonly used. Lung function can deteriorate with these procedures, and we have investigated the effects on lung mechanics and oxygenation in healthy piglets. METHODS: The lungs of anesthetized and mechanically ventilated piglets were recruited with CPAP 35 cmH2O. Thereafter we instilled 5 ml of saline into the endotracheal tube, followed by three breaths from the ventilator. Saline was retrieved through a suction catheter wedged far distally in the airway. The procedure was followed by a new recruitment maneuver. Complete inspiratory/expiratory pressure - volume loops (PV-loops) were obtained just before and 5 min after saline instillation. Arterial blood gases were collected at equivalent times in 14 similar piglets submitted to exactly the same procedure. RESULTS: The inspiratory limb of the PV-loops changed markedly, as the lower inflection point was displaced towards higher pressures (P=0.004), and hysteresis measured at 15 and 30 cmH2O increased (P=0.004 and P=0.012, respectively). Although PaO2 decreased significantly (P=0.001), values after saline instillation/suctioning were still in the high normal range, that is, 22.2 +/- 2.6 kPa. CONCLUSIONS: Opening pressures of the lungs increase markedly after saline instillation/suctioning in healthy piglets. In this situation, adequate recruitment maneuvers and PEEP might prevent lung collapse and deteriorations in arterial oxygenation.

Incomplete protection by prophylactic surfactant against the adverse effects of large lung inflations at birth in immature lambs.

OBJECTIVE: To investigate whether preceding surfactant instillation prevents the harmful effect of large lung inflations at birth in immature lambs, and, if not, to find out for how long the immature lung remains sensitive to large inflations. DESIGN: In an exploratory study, 12 preterm lambs given surfactant at birth were randomized to receive five large lung inflations at four different times: at birth just before or immediately after surfactant treatment; at 10 min; or at 60 min of age. In a confirmatory study, 10 pairs of preterm lamb twins were all given surfactant before the first breath. One lamb in each pair was randomised to receive large lung inflations immediately after surfactant while the other twin underwent similar inflations at 10-15 min of age. SETTING: Animal laboratory. EXPERIMENTAL ANIMALS: Anaesthetized lambs delivered by cesarean section at a gestational age of 127 days. INTERVENTIONS: Surfactant supplementation at birth. Five sustained lung inflations of 16 ml/kg at different times in relation to surfactant instillation. Pressure-limited mechanical ventilation for 4 h. MEASUREMENTS AND RESULTS: The response to surfactant was assessed by ventilator settings, lung mechanics and lung histology. Preceding surfactant supplementation did not prevent the adverse effect of large lung inflations at birth on ventilatory efficiency and lung mechanics, but seemed to protect against severe lung injury. No adverse effect was seen from large lung inflations given at 10 min of age or later. CONCLUSION: Prophylactic surfactant supplementation does not fully protect against the harmful effect of large lung inflations during a short sensitive period immediately after birth.

Coronary flow reserve in the newborn lamb: an intracoronary Doppler guide wire study.

Recent studies indicate a severely reduced coronary flow reserve (CFR) in neonates with congenital heart disease. The significance of these studies remains debatable, as the ability of the anatomically normal neonatal heart to increase coronary flow is currently unknown. This study was designed to establish normal values for CFR in newborns after administration of adenosine [pharmacologic CFR (pCFR)] and as induced by acute hypoxemia (reactive CFR). Thirteen mechanically ventilated newborn lambs were studied. Coronary flow velocities were measured in the proximal left anterior descending coronary artery before and after adenosine injection (140 and 280 microg/kg i.v.) using an intracoronary 0.014-in Doppler flow-wire. Measurements were made at normal oxygen saturation (SaO(2)) and during progressive hypoxemia induced by lowering the fraction of inspired oxygen. CFR was defined as the ratio of hyperemic to basal average peak flow velocity. In a hemodynamically stable situation with normal SaO(2), pCFR was 3.0 +/- 0.5. pCFR decreased with increasing hypoxemia. Regression analysis showed a linear relation between SaO(2) and pCFR (R = 0.86, p < 0.0001). Reactive CFR obtained at severe hypoxemia (Sao(2) <30%) was 4.2 +/- 0.8, and no significant further increase in coronary flow velocity occurred by administration of adenosine. Newborn lambs have a similar capacity to increase coronary flow in response to both pharmacologic and reactive stimuli as older subjects. Administration of adenosine does not reveal the full capacity of the newborn coronary circulation to increase flow, however, as the flow increase caused by severe hypoxemia is significantly more pronounced.