effect of positive pressure ventilatory patterns on post-bypass lung functions

This study aimed at evaluating the effect of application of different patterns of positive ventilatory pressure either during or after cardiopulmonary bypass [CPB], on lung functions. 30 patients undergoing coronary artery revascularisation under the management of CPB were randomly allocated into 3 groups. Group I [VCM] 10 patients were subjected to manual vital capacity manoeuvre [VCM] before weaning off the CPB. Group II [CPAP] 10 patients were subjected to continuous positive airway pressure [CPAP] of 10 cm H[2]O during CPB. Group III [PEEP] 10 patients were subjected to positive end expiratory pressure [PEEP] of 7 cmH[2]O after weaning off the CPB. Measurements included the PO[2] PCO[2] together with derived calculated parameters as the alveolar-arterial oxygen difference [P [A-a] DO[2]] and shunt fraction, as welt as the dynamic lung compliance being recorded directly from the anesthetic and ventilatory equipments. All readings were taken on closed chest and on FiO[2] of 0.5. Intraoperative anesthetic and surgical data as well as postoperative extubation time and length of ICU stay were also evaluated. Statistical analysis of ventilatory parameters showed no significant differences for both PO[2] and PCO[2] in between the studied groups. Alveolar-Arterial oxygen difference mean values were comparable in the 3 studied groups. The mean values of intrapulmonary shunt fraction showed a significant difference in relation to the baseline values in Group I [VCM] and Group III [PEEP] at 30 minutes after ICU admission and 4 hours post CPB with estimated P value <0.01 and <0.05 respectively, while in Group II [CPAP] mean values started to be significant after chest closure with a P value <0.05, but there was no significant intergroup differences with a P value >0.01. Dynamic lung compliance mean values showed no intergroup statistical significance. Maintenance of ventilatory parameters was achieved in all the positive pressure ventilatory methods applied, either being applied during or after CPB

Low central venous pressure anaesethesia in major hepatic resection

Blood loss and transfusion requirements are major determinants of morbidity and mortality following liver resection. This study evaluates the association of low central venous pressure [LCVP] with blood loss and blood transfusion during liver resection. Thirty consecutive hepatic resections were studied prospectively concerning CVP, volume of blood loss and volume of blood transfusion and renal outcome. Data were analyzed for those with a CVP 5 mmHg. A muitivariate analysis assessed potential confounding factors in the comparison. The mean blood loss in patients with a CVP of 5 mmHg or less was < 500 ml and that in those with a CVP > 5 mmHg was > 2000 ml. [p <0.0001]. Only two patients with a CVP of 5 mmHg required transfusion. No incidences of air embolism or permanent renal shutdown have been reported. In conclusion: The volume of blood loss and blood transfusion during liver resection correlates with the CVP during parenchyma! transection. Lowering the CVP to less than 5 mmHg is a simple and effective technique to reduce blood loss during liver resection and delete the need for blood transfusion with its hazards