Bedside estimates of dead space using end-tidal CO2 are independently associated with mortality in ARDS

Purpose In acute respiratory distress syndrome (ARDS), dead space fraction has been independently associated with mortality. We hypothesized that early measurement of the difference between arterial and end-tidal CO2 (arterial-ET difference), a surrogate for dead space fraction, would predict mortality in mechanically ventilated patients with ARDS. Methods We performed two separate exploratory analyses. We first used publicly available databases from the ALTA, EDEN, and OMEGA ARDS Network trials (N = 124) as a derivation cohort to test our hypothesis. We then performed a separate retrospective analysis of patients with ARDS using University of Chicago patients (N = 302) as a validation cohort. Results The ARDS Network derivation cohort demonstrated arterial-ET difference, vasopressor requirement, age, and APACHE III to be associated with mortality by univariable analysis. By multivariable analysis, only the arterial-ET difference remained significant (P = 0.047). In a separate analysis, the modified Enghoff equation ((PaCO2–PETCO2)/PaCO2) was used in place of the arterial-ET difference and did not alter the results. The University of Chicago cohort found arterial-ET difference, age, ventilator mode, vasopressor requirement, and APACHE II to be associated with mortality in a univariate analysis. By multivariable analysis, the arterial-ET difference continued to be predictive of mortality (P = 0.031). In the validation cohort, substitution of the arterial-ET difference for the modified Enghoff equation showed similar results. Conclusion Arterial to end-tidal CO2 (ETCO2) difference is an independent predictor of mortality in patients with ARDS.

Delayed tracheal extubation after cardiac surgery due to cardiogenic ventilator auto-triggering: a case report

Background Ventilator auto-triggering is associated with poor outcomes. Herein, we present a case of delayed tracheal extubation after cardiac surgery due to cardiogenic auto-triggering. Case presentation A 73-year-old male with chronic constrictive pericarditis underwent radical pericardiectomy. After confirming hemodynamic stability, we conducted spontaneous breathing trial (SBT) with a flow-trigger sensitivity of 1 L/min. As his respiratory rate (RR) increased to more than 60 breaths/min and tidal volume decreased to less than 100 mL, this SBT was considered a failure. Next morning, SBT was reperformed and the result was unchanged. However, we noticed that his heart rate and RR were the same and suspected auto-triggering caused by cardiogenic oscillations. We changed ventilator mode from flow triggering to pressure triggering of −2 cmH2O and he was uneventfully extubated. Conclusion We experienced a case of delayed tracheal extubation after cardiac surgery due to cardiogenic auto-triggering. Auto-triggering can be reduced by changing ventilator trigger mode.

120 A Survey of Burn Care Professionals to Characterize Patterns of Early Mobility in ICU Burn Patients

Introduction Early mobility in intensive care unit (ICU) patients has been demonstrated effective in improving functional status, range of motion, preventing complications, and decreasing length of stay. There is limited data regarding the early mobilization of burn ICU patients. The purpose of this study was to survey burn care providers to better understand their experience with early mobilization and explore perceived barriers and contraindications. Methods An internet-based 21-item survey was distributed to burn professionals at North American burn centers and units. Descriptive statistics were performed. Results There were a total of 63 respondents. Most respondents were physical therapists (33%), occupational therapists (33%), or nurses (25%), with >5 years of burn care experience (71%). Early mobility was characterized as both in bed and out of bed activities within 24 hours of ICU admission, up to any time during the course of mechanical ventilation or ICU stay. The majority of respondents (54%) indicated they mobilize patients on ventilators in bed and out of bed, while there was an even split on whether or not patients on vasopressor support were mobilized. Of those respondents (46%) who use the Richmond Agitation-Sedation Scale (RASS) to guide mobility, 14% mobilize patients with a RASS of -4 or -5 and 41% mobilize patients with a RASS of -3 to -2. The highest appropriate score for mobilization was +1 to +2 (76%). Hgb/Hct, line presence, ventilator mode, mental status, and vital signs were viewed as precautions to discuss with the medical team, rather than a contraindication to mobility. Respiratory rate < 6 and presence of ECMO were the areas of most concern, with the majority respondents indicating they would likely hold mobility. Most respondents indicated that they would mobilize any burn ICU patients after discussion with the medical team if necessary. The majority of respondents (72%) indicated that they did not have an early mobilization protocol for burn ICU patients. Conclusions There is a paucity of evidence available for early mobility in burn ICU patients. This survey demonstrates a lack of consensus regarding what constitutes early mobility and when patients should be mobilized. A multi-center observational trial is needed to inform the development of an evidence-based mobility protocol.

304 DOES INTRAOPERATIVE FLUID MANAGEMENT INFLUENCE THE POSTOPERATIVE HOSPITALIZATION IN PATIENTS UNDERGOING ROBOTIC-ASSISTED ESOPHAGECTOMY

Esophageal resection is a formidable surgery which is often associated with high morbidity and mortality rate despite an improvement in postoperative care. Fluid administration has been described to be a major factor that contributes to the development of postoperative complications after esophagectomy. The aim was to study the relationship between intraoperative fluid administration and the postoperative hospitalization stay Methods After hospital ethical committee approval, 69 patients who underwent Robotic-assisted esophagectomy dated from January 2011 to till date were accessed from the hospital electronic databank. Single lung ventilation was used in all of the patients during the thoracic approach. 69 patients were divided into two groups with respect to patients in first group who received 4 litres and below and the second group who received 4litres and above of crystalloids. Variables studied were ASA status, demographic data, intraoperative fluids administered, ventilator mode, positioning, postoperative parameters studied were icu stay, sepsis, ionotropic support, respiratory distress, reexploration, readmission to icu. Results None of the variables studied except fluid administration were shown as risk factor. Conclusion Anesthetic regimen directed at a restrictive intraoperative fluid of less than 4 litres has reduced the postoperative morbidity rates and the duration of hospital stay in patients undergoing Robotic esophagectomy.

710 Use of Airway Pressure Relief Ventilation (APRV) in Burn Patients with and Without Inhalation Injury

Introduction Burn patients often require ventilator management because of large % TBSA injury, the presence of inhalation injury, and/or other factors. Airway pressure relief ventilation (APRV) offers several advantages over conventional ventilation modes including improved alveolar recruitment, better oxygenation and hemodynamics, preservation of spontaneous breathing, and possibly less ventilator-induced lung injury. This study reviews the use of APRV as the primary ventilator mode in burn patients with and without inhalation injury. Methods A retrospective chart review of patients admitted to the burn center and requiring APRV ventilation over a ten year period was performed. Data collected included demographic data, burn injury data, ventilator settings, arterial blood gas data, and development of ventilator-associated pneumonia (VAP). Results There were 411 patients identified over the ten year period. Mean age was 46 years, and mean % TBSA burned was 33. Seventy-three percent were male. One-half (51%) of patients had an inhalation injury. Mean hospital length of stay was 32 days with 22 mean ventilator days. Average number of surgeries was 4.4 per patient. Mean high pressure (P high) was 23 mm Hg. Mean FiO2 was 88% on post-injury day (PID) 1, 65% on day PID 2, and 45% thereafter. Mean P/F ratio was 333. Mean pH was 7.40, mean pCO2 was 40 mmHg, and mean HCO3 was 25 mm Hg. Forty-six percent of patients met criteria for diagnosis of VAP. Conclusions These data demonstrate that burn patients requiring mechanical ventilation can be safely and effectively managed with APRV. Oxygenation, carbon dioxide removal, normal acid-base status, and excellent P/F ratios were maintained with relatively low ventilator settings such as peak airway pressure and FiO2. Patients were able to breathe spontaneously when able and were easily liberated form the ventilator at the appropriate time. Applicability of Research to Practice This study defines an unconventional and potentially improved ventilator mode use in burn patients.

The time-controlled adaptive ventilation protocol: mechanistic approach to reducing ventilator-induced lung injury

Airway pressure release ventilation (APRV) is a ventilator mode that has previously been considered a rescue mode, but has gained acceptance as a primary mode of ventilation. In clinical series and experimental animal models of extrapulmonary acute respiratory distress syndrome (ARDS), the early application of APRV was able to prevent the development of ARDS. Recent experimental evidence has suggested mechanisms by which APRV, using the time-controlled adaptive ventilation (TCAV) protocol, may reduce lung injury, including: 1) an improvement in alveolar recruitment and homogeneity; 2) reduction in alveolar and alveolar duct micro-strain and stress-risers; 3) reduction in alveolar tidal volumes; and 4) recruitment of the chest wall by combating increased intra-abdominal pressure. This review examines these studies and discusses our current understanding of the pleiotropic mechanisms by which TCAV protects the lung. APRV set according to the TCAV protocol has been misunderstood and this review serves to highlight the various protective physiological and mechanical effects it has on the lung, so that its clinical application may be broadened.

General: The Asthmatic Patient

In this chapter the essential aspects of managing the asthmatic patient before, during, and after surgery are reviewed. The chapter is divided into preoperative, intraoperative, and postoperative sections with important subtopics related to the main topic in each section. The case involves a woman with type 2 diabetes mellitus who is scheduled for urgent laparoscopic, possibly open, cholecystectomy. Issues addressed for preoperative evaluation include assessment for whether the patient is optimized for urgent surgery, hemoglobin A1C test, and premedication. Intraoperative topics include induction, selecting a ventilator mode, and managing complications. Postoperative concerns discussed include extubation criteria and management of glucose levels.