Devising negative pressure within intercuff space reduces microaspiration.

BACKGROUND: Microaspiration past the tracheal tube cuffs causes ventilator-associated pneumonia. The objective of the current study was to evaluate whether creating negative pressure between the tracheal double cuffs could block the fluid passage past the tracheal tube cuffs. METHODS: A new negative pressure system was devised between the double cuffs through a suction hole in the intercuff space. Blue-dyed water was instilled above the cuff at negative suction pressures of - 54, - 68, - 82, - 95, - 109, - 122, and - 136 cmH2O, and the volume leaked was measured in an underlying water trap after 10 min. Leakage tests were also performed during positive pressure ventilation, and using higher-viscosity materials. The actual negative pressures delivered at the hole of double cuffs were obtained by placing microcatheter tip between the intercuff space and the artificial trachea. RESULTS: No leakage occurred past the double cuff at - 136 cmH2O suction pressure at all tracheal tube cuff pressures. The volume leaked decreased significantly as suction pressure increased. When connected to a mechanical ventilator, no leakage was found at - 54 cmH2suction pressure. Volume of the higher-viscosity materials (dynamic viscosity of 63-108 cP and 370-430 cP) leaked was small compared to that of normal saline (0.9-1.1 cP). The pressures measured in the intercuff space corresponded to 3.8-5.9% of those applied. CONCLUSIONS: A new prototype double cuff with negative pressure in the intercuff space completely prevented water leakage. The negative pressure transmitted to the tracheal inner wall was a small percentage of that applied.

Low central venous pressure with milrinone during living donor hepatectomy.

Maintaining a low central venous pressure (CVP) has been frequently used in liver resections to reduce blood loss. However, decreased preload carries potential risks such as hemodynamic instability. We hypothesized that a low CVP with milrinone would provide a better surgical environment and hemodynamic stability during living donor hepatectomy. Thirty-eight healthy adult liver donors were randomized to receive either milrinone (milrinone group, n = 19) or normal saline (control group, n = 19) infusion during liver resection. The surgical field was assessed using a four-point scale. Intraoperative vital signs, blood loss, the use of vasopressors and diuretics and postoperative laboratory data were compared between groups. The milrinone group showed a superior surgical field (p < 0.001) and less blood loss (142 +/- 129 mL vs. 378 +/- 167 mL, p < 0.001). Vital signs were well maintained in both groups but the milrinone group required smaller amounts of vasopressors and less-frequent diuretics to maintain a low CVP. The milrinone group also showed a more rapid recovery pattern after surgery. Milrinone-induced low CVP improves the surgical field with less blood loss during living donor hepatectomy and also has favorable effects on intraoperative hemodynamics and postoperative recovery.