Beth Israel Deaconess Medical Center
In the past 5 years, there are increasing data suggesting that patients treated with mechanical ventilation experience shortness of breath, despite appropriate sedation. This adverse experience is believed to contribute to the finding that up to 25% of patients who survive severe respiratory diseases experience mental health problems including post traumatic distress syndrome (PTSD). The purpose of this study is to evaluate if/how sequential changes in the delivery of mechanical ventilation affect shortness of breath sensation in awake patients requiring mechanical ventilation. Improving the knowledge of the impact of the patient-ventilator interaction on shortness of breath sensation may lead to strategies to improve the comfort of non-sedated and sedated ventilated patients, and thereby reduce mental health sequelae in survivors of acute severe respiratory diseases The investigators hypothesize that current ventilator strategies, particularly reduced tidal volume (size of breath given by the ventilator) utilized in managing patients with severe respiratory diseases, contribute to shortness of breath in patients with increased drive to breathe. In this setting, some safe ventilator changes may improve or worsen the shortness of breath sensation in awake patients on mechanical ventilation.
For patients who develop acute respiratory failure, endotracheal tube (ETT) intubation and mechanical ventilation represent a potentially life-saving intervention to provide support for breathing and allow the opportunity for lungs to recover from critical illness. Current standard practice for mechanical ventilation varies, and includes selecting mechanical ventilator mode (including volume-cycled or pressure-cycled), and routine adjustments of ventilator settings \[including settings such as flow rate, tidal volume (Vt), positive end-expiratory pressure (PEEP)\]. To assess and confirm the c…
Inclusion Criteria: * Admitted to a participating ICU at BIDMC * Requiring mechanical ventilation * Awake by both of the following criteria * RASS -2 to +2\* * CAM-ICU negative‡ * Able to communicate/answer dyspnea questionnaire * RASS (Richmond Agitation-Sedation Scale) is a validated scale commonly used in the ICU to assess patient's level of sedation and agitation. It ranges from -5 to +4. While -5 means an unarousable coma, +4 means violent patient with immediate self danger. The scale from -2 to +2 ranges from light sedation to agitated. * CAM-ICU (Confusion Assessment Method) is…
All patients will be set on volume control/assist control (VC/AC) with flow at ramp and appropriate settings to approximate their initial tidal volume, minute ventilation, respiratory rate, FiO2 and PEEP. This change is routinely performed in the ICU. Patients already on VC/AC will be kept on same settings. The investigators will check dyspnea after this initial change.
Change in 2mL/kg (increase and/or decrease) for 3 minutes. After every change the patient will rate dyspnea with an ordinal scale and The investigators will assess occlusion pressure at the mouth at the onset of inspiration (P0.1 and Pocc).
Increase in 25% of baseline flow for 3 minutes Decrease in 25% of baseline flow for 3 minutes After every change the patient will rate dyspnea with an ordinal scale and the investigators will assess occlusion pressure at the mouth at the onset of inspiration (P0.1 and Pocc).
Change in PEEP by 5 cmH2O After every change the patient will rate dyspnea with an ordinal scale and the investigators will assess occlusion pressure at the mouth at the onset of inspiration (P0.1 and Pocc).
Change to PSV to match their initial settings. After every change the patient will rate dyspnea with an ordinal scale and The investigators will assess occlusion pressure at the mouth at the onset of inspiration (P0.1 and Pocc).