Effect of Mode of Transport Ventilation on Respiratory Parameters After Cardiac Surgery

Overview

After cardiac surgery patients are transported from the operating room (OR) to the intensive care unit (ICU) while intubated. Two principal methods of oxygenation and ventilation are used: (1) a transport ventilator or (2) a Mapleson Bag-Mask hand ventilating circuit. The choice of method is largely determined by the preference of the the anesthesiologist who is transporting the patient. The investigators postulate that the choice of either method might alter respiratory and hemodynamic parameters felt to be important for the immediate management of post-cardiac surgery patients. The investigators will prospectively record end-tidal carbon dioxide (ETCO2) (primary end-point) and change in minute volume, heart rate (HR), Blood pressure (BP), pulmonary artery (PA) pressures and cardiac output during transportation and upon arrival in the ICU. All of these variables are measured routinely but are not recorded. The investigators will compare patients transported with a ventilator to patients transported with a Mapleson circuit.

After cardiac surgery, patients can have poor respiratory function and hemodynamics. The exact cause and contributing factors of this deterioration are not usually known and, often these patients demonstrate normal parameters at the end of surgery, but are significantly altered upon arrival in the ICU. Transportation of patients from the OR to the ICU is a period of significantly less intense monitoring and less well-controlled interventions (for example tidal volume (Vt) is largely arbitrary). Recent evidence suggests that the risk of intra-hospital transportation is significantly higher for ventilated patients than for all other patients. Some of this risk might be mitigated by the mode of ventilation because pulmonary and hemodynamic parameters are rarely measured during transportation. If the method used for ventilation and oxygenation during transport is important in maintaining stability upon presentation to the ICU, clinicians might choose one method over another. This would change clinical practice. This is a prospective observational study assessing the effect of different modes of transport ventilation on respiratory and hemodynamic parameters on post cardiothoracic (CT) surgery patients admitted to the ICU. It is standard of care to measure peripheral blood CO2 (either end-tidal or arterial), minute volume, heart rate, blood pressure, cardiac output and pulmonary artery pressure for all patients admitted to the ICU after cardiac surgery. The investigators will simply record these values during transport and immediately on arrival in the ICU. At a 2 sided significance level of 0.05, the investigators will enroll 32 patients to detect a minimal difference from baseline ETCO2 of 15% at a power of 0.8. The investigators will review each subjects medical record to obtain vital sign information and ventilatory parameters. The investigators will obtain individual HIPAA authorization from each subject. All subjects will have just undergone cardiac surgery are intubated and are being transported to the ICU with either method of ventilation. The patients will be adult (age 18 and over who are competent to give their own consent). They will be recruited prior to surgery according to the inclusion and exclusion criteria listed below. No consideration will be made to gender, race, sexual orientation or national origin.