Assessing fluid-responsiveness by a standardized ventilatory maneuver: the respiratory systolic variation test

Respiratory-induced changes in arterial blood pressure predict fluid responsiveness. However, the accuracy of these variables is affected by the preset tidal volume and by the early inspiratory increase in arterial blood pressure. We have therefore calculated the slope produced by the minimal systolic blood pressures (plotted against the respective airway pressures) during a ventilatory maneuver consisting of four incremental, successive, pressure-controlled breaths, termed the Respiratory Systolic Variation Test (RSVT). In 14 ventilated patients, after major vascular surgery, the slope of the RSVT decreased significantly after intravascular fluid administration and correlated with the end-diastolic area and with changes in cardiac output better than filling pressures. This preliminary study suggests that a standardized ventilatory maneuver may be useful in guiding fluid therapy in ventilated patients.     

Nasogastric tubes after cardiac surgery: Impact on nausea and vomiting

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Effects of alveolar recruitment on arterial oxygenation in patients after cardiac surgery: a prospective, randomized, controlled clinical trial

OBJECTIVE: Pulmonary atelectasis and hypoxemia remain considerable problems after cardiac surgery. The objective of this study was to determine the efficacy of consecutive vital capacity maneuvers (C-VCMs) to improve oxygenation in patients after cardiac surgery. STUDY DESIGN: Randomized, controlled clinical trial. SETTING: Tertiary referral teaching center. PARTICIPANTS: Ninety-five patients requiring elective cardiac surgery with cardiopulmonary bypass (CPB). INTERVENTION: Patients were randomly allocated to either C-VCM or control groups. In the C-VCM group, lung inflation at pressure of 35 cmH(2)O was sustained for 15 seconds before separation from CPB and at 30 cmH(2)O for 5 seconds after admission to the intensive care unit (ICU). MEASUREMENTS AND MAIN RESULTS: The primary outcome was the ratio of arterial oxygen tension to inspired oxygen fraction measured at the following predetermined time intervals: after induction of anesthesia, 15 minutes after separation from CPB, after admission to the ICU, after 3 hours of positive-pressure ventilation, after extubation, and before ICU discharge. C-VCM resulted in better arterial oxygenation extending from the immediate postoperative period to approximately 24 hours after surgery at the time of ICU discharge. There were no significant adverse events related to C-VCM application. CONCLUSION: C-VCM is an effective method to reduce hypoxemia associated with the formation of atelectasis after cardiac surgery with CPB.     

Non-invasive measurements of cardiac output after cardiac surgery

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

End-inspiratory rebreathing reduces the end-tidal to arterial PCO<Subscript>2</Subscript> gradient in mechanically ventilated pigs

Purpose  

Noninvasive monitoring of the arterial partial pressures of CO₂ (PaCO₂) of critically ill patients by measuring their end-tidal partial pressures of CO₂ (PetCO₂) would be of great clinical value. However, the gradient between PetCO₂ and PaCO₂ (Pet-aCO₂) in such patients typically varies over a wide range. A reduction of the Pet-aCO₂ gradient can be achieved in spontaneously breathing healthy humans using an end-inspiratory rebreathing technique. We investigated whether this method would be effective in reducing the Pet-aCO₂ gradient in a ventilated animal model.