Preventing Respiratory Failure After Cardiac Surgery Using Post-extubation Bilevel Positive Airway Pressure Therapy.

OBJECTIVE: Our study aimed to evaluate if an extubation protocol for all post-operative cardiac patients in the cardiothoracic intensive care unit using intermittent bilevel positive airway pressure (BiPAP) could reduce the rate of re-intubation. METHODS: A total of 1,718 patients undergoing cardiac surgery from May 2012 to April 2016 were analyzed. Patients from May 2014 to April 2016 were included in a post-extubation BiPAP therapy protocol that included one hour of BiPAP followed by three hours of a nasal cannula for 24 hours after extubation in the cardiothoracic intensive care unit. The protocol cohort was retrospectively compared to a control group (nasal cannula only) from May 2012 to April 2014. All demographic and outcome data were analyzed from our institution's Society of Thoracic Surgeons (STS) Cardiac Database. RESULTS: There was no statistical difference in the rate of re-intubation between the BiPAP group (n = 35; 4.07%) and the control group (n = 34; 3.96%; p = 0.9022). Sub-group analysis of the 69 re-intubated patients identified several significant risk factors: prior valve surgery (p = 0.028), chronic lung disease (p = 0.0343), emergent operation (p = 0.0016), longer operating room time (p = 0.0109), cardiopulmonary bypass time (p = 0.0086), higher STS predicted risk of mortality score (p = 0.0015). Re-intubation was associated with higher 30-day mortality rates (p = 0.0026), prolonged cardiothoracic intensive care unit length of stay (p < 0.0001), and hospital length of stay (p < 0.0001). CONCLUSION: While a BiPAP protocol did not show a significant difference in re-intubation rates after cardiac surgery, the subgroup analysis of re-intubated patients showed several significant risk factors for re-intubation. Early identification of these risk factors when considering extubation may help teams avoid associated morbidity and mortality outcomes.

Perioperative management of special populations: the geriatric patient.

Americans over age 65 represent the fastest growing segment of the United States population. As a result, the demographic landscape of America is changing. Knowledge of aged physiology is necessary to construct a risk-benefit analysis tailored for each patient to improve perioperative outcomes and lower the morbidity and mortality rates among the elderly. Benefit estimates should account for a patient's life expectancy and quality of life before and after surgery. With aging, baseline functions of almost every organ system undergo progressive decline resulting in a decreased physiologic reserve and ability to compensate for stress. Pain control, postoperative cognitive dysfunction, end-of-life issues, and realistic expectations after surgery are paramount issues throughout the perioperative period.

Seventy-two hour gas exchange performance and hemodynamic properties of NOVALUNG iLA as a gas exchanger for arteriovenous carbon dioxide removal.

OBJECTIVE: Acute respiratory failure is complicated by acidosis and altered end-organ perfusion. NOVA-LUNG iLA is an interventional lung assist (ILA) device for arteriovenous carbon dioxide removal (AVCO2R). The present study was conducted to evaluate the device for short-term CO2 removal performance and hemodynamic response. METHODS: Six adult sheep received cannulation of the jugular vein and carotid artery. The ILA-AVCO2R circuit was placed on the sheep for 72 hours. Hemodynamics and PaCO2 were measured; CO2 removal was calculated while varying sweep gas flow rates (Qg), device blood flow rates (Qb), and PaCO2. RESULTS: Hemodynamic variables remained normal throughout the 72 hour study. CO2 removal increased with increases in Qg or Qb. Mean CO2 removal was 119.3 ml/min for Qb 1 L/ min, Qg 5 L/min, and PaCO2 40-50 mmHg. PaCO2 was directly proportional to CO2 clearance (R=0.72, p <0.001). CONCLUSION: NOVALUNG iLA can provide near total CO2 removal with Qb 1-2 L/min, Qg 5 L/min, and minimal flow resistance (3.88+/-0.82 mmHg/L/min). PaCO2 correlates with CO2 removal and is dependent on Qb and Qg.

Development of ambulatory arterio-venous carbon dioxide removal (AVCO2R): the downsized gas exchanger prototype for ambulation removes enough CO2 with low blood resistance.

We are developing an ultra compact gas exchanger to allow ambulation during arterial-venous CO2 removal (AVCO2R). The ambulatory AVCO2R gas exchanger (135 ml prime volume and 1.3 M2 gas exchange surface area) is made of polymethylpentene hollow fibers. The gas exchanger was attached to sheep carotid artery (12F) and jugular vein (14F) by percutaneous cannulae for 6 hours (n = 5). Device CO2 removal was measured and calculated at a constant blood flow rate of 1 L/min coupled with varying sweep gas from 1 to 15 L/min, and at constant sweep gas flow of 2 L/min coupled with varying blood flow from 0.5 to 1.25 L/min to determine capacity of CO2 removal at Pa CO2 = 40-50 mm Hg. Blood gases, CO2 removal and hemodynamics were recorded at 0, 3, and 6 hours. CO2 removal increased with sweep gas flow rate and with increase of device blood flow. Hemodynamics remained unchanged throughout study. Gas exchanger resistance remained stable at 2.3 +/- 0.53 mm Hg/L/min. CO2 removal with 1 L/min blood flow and 2 L/min sweep gas was 110 +/- 12 then stabilized at 85 +/- 14 mL/min to 6 hours. The compact ambulatory AVCO2R gas exchanger achieves stable, near total CO2 removal for at least 6 hours with a simple arteriovenous shunt.

Deep venous thrombosis prophylaxis in trauma: improved compliance with a novel miniaturized pneumatic compression device.

OBJECTIVE: Intermittent pneumatic compression (IPC) devices prevent lower-extremity deep venous thrombosis (LEDVT) when used properly, but compliance remains an issue. Devices are frequently discontinued when patients are out of bed, and they are rarely used in emergency departments. Trauma patients are at high risk for LEDVT; however, IPCs are underused in this population because of compliance limitations. The hypothesis of this study was that a new miniaturized, portable, battery-powered pneumatic compression device improves compliance in trauma patients over that provided by a standard device. METHODS: This was a prospective trial in which trauma patients (mean age, 46 years; revised trauma score, 11.7) were randomized to DVT prophylaxis with a standard calf-length sequential IPC device (SCD group) or a miniaturized sequential device (continuous enhanced-circulation therapy [CECT] group). The CECT device can be battery-operated for up to 6 hours and worn during ambulation. Timers attached to the devices, which recorded the time each device was applied to the legs and functioning, were used to quantify compliance. For each subject in each location during hospitalization, compliance rates were determined by dividing the number of minutes the device was functioning by the total minutes in that location. Compliance rates for all subjects were averaged in each location: emergency department, operating room, intensive care unit, and nursing ward. RESULTS: Total compliance rate in the CECT group was significantly higher than in the SCD group (77.7% vs. 58.9%, P =.004). Compliance in the emergency department and nursing ward were also significantly greater with the CECT device (P =.002 and P =.008 respectively). CONCLUSIONS: Previous studies have demonstrated that reduced compliance with IPC devices results in a higher incidence of LEDVT. Given its ability to improve compliance, the CECT may provide superior DVT prevention compared with that provided by standard devices.

Pneumothorax in patients with acute respiratory distress syndrome: pathophysiology, detection, and treatment.

Pneumothorax is a frequent and potentially fatal complication of mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Prompt recognition and treatment of pneumothoraces is necessary to minimize morbidity and mortality. The radiologic and clinical signs of pneumothoraces in ARDS patients may have unusual and subtle features. Furthermore, small pneumothoraces in these patients can cause severe hemodynamic or pulmonary compromise. Sparse clinical literature exists on when or how to treat pneumothoraces once they develop in patients with ARDS. In this article, the authors review the pathogenesis, radiologic signs, clinical significance, and treatment of pneumothoraces in ARDS patients. Treatment options include traditional tube thoracostomy, open thoracotomy, and image-guided percutaneous catheters.

Predictors of alveolar air leaks.

Persistent air leaks are caused by the failure of the postoperative lung to achieve a configuration that is physiologically amenable to healing. The raw pulmonary surface caused by the dissection of the fissure often is separated from the pleura, and the air leak fails to close. Additionally, higher air flow thorough an alveolar-pleural fistula seems to keep the fistula open. Other factors that interfere with wound healing, such as steroid use, diabetes, or malnutrition, can result in persistence of the leak. A thoracic surgeon can minimize the incidence of air leak through meticulous surgical technique and can identify patients in whom the balance of risks (Table 1) and benefits warrant operative intervention based on an understanding of the underlying pathophysiology.