Venovenous extracorporeal membrane oxygenation for respiratory failure refractory to high frequency percussive ventilation.

BACKGROUND: High frequency percussive ventilation (HFPV) has demonstrated improvements in gas exchange, but not in clinical outcomes. OBJECTIVES: We utilize HFPV in patients failing conventional ventilation (CV), with rescue venovenous extracorporeal membrane oxygenation (VV ECMO) reserved for failure of HFPV, and we describe our experience with such a strategy. METHODS: All adult patients (age >18 years) placed on HFPV for failure of CV at a single institution over a 10-year period were included. Those maintained on HFPV were compared to those that failed HFPV and required VV ECMO. Survival was compared to expected survival after upfront VV ECMO as estimated by VV ECMO risk prediction models. RESULTS: Sixty-four patients were placed on HFPV for failure of CV over a 10-year period. After HFPV initiation, the P/F ratio rose from 76mmHg to 153.3mmHg in the 69 % of patients successfully maintained on HFPV. The P/F ratio only rose from 60.3mmHg to 67mmHg in the other 31 % of patients, and they underwent rescue ECMO with the P/F ratio rising to 261.6mmHg. The P/F ratio continued to improve in HFPV patients, while it declined in ECMO patients, such that at 24 h, the P/F ratio was greater in HFPV patients. The strongest independent predictor of failure of HFPV requiring rescue VV ECMO was a lower pO2 (p = .055). Overall in-hospital survival (59.4 %) was similar to that expected with upfront ECMO (RESP score: 57 %). CONCLUSIONS: HFPV demonstrated significant and sustained improvements in gas exchange and may obviate the need for ECMO and its associated complications.

Renal replacement therapy in patients on extracorporeal membrane oxygenation support: Who and how.

Patients undergoing extracorporeal membrane oxygenation (ECMO) support frequently develop renal failure requiring renal replacement therapy (RRT). RRT may be performed via a dialysis catheter based approach or via the ECMO circuit. We describe our experience with both techniques. A total of 68 patients undergoing ECMO support at our institution were retrospectively analyzed. Predictors of renal failure requiring RRT were determined. Patients undergoing RRT via a dialysis catheter were compared with those undergoing RRT via the ECMO circuit. 10 of the 68 patients required RRT support prior to ECMO. Of the remaining 58 patients, 25 (43%) required new RRT support on ECMO. Lower albumin levels and postcardiotomy shock were predictive of new renal failure requiring RRT on ECMO. RRT performed via the ECMO circuit demonstrated similar efficacy as via a dialysis catheter. Outcomes were much worse for patients requiring new RRT on ECMO support, with a doubling of the length of ECMO support and less that one-third the survival rate of patients not requiring RRT on ECMO support. New renal failure requiring RRT occurs in nearly one-half of patients on ECMO support, with poor outcomes. RRT may be performed via the ECMO circuit with similar efficacy as via a dialysis catheter.

A comparison of existing risk prediction models in patients undergoing venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Patients undergoing consideration for venoarterial extracorporeal membrane oxygenation (VA-ECMO) require an immediate risk profile assessment in the setting of incomplete information. A number of survival prediction models for critically ill patients and patients undergoing elective cardiac surgery or institution of VA-ECMO support have been designed. We assess the ability of these models to predict outcomes in a cohort of patients undergoing institution of VA-ECMO for cardiogenic shock or cardiac arrest. METHODS: Fifty-one patients undergoing institution of VA-ECMO support were retrospectively analyzed. APACHE II, SOFA, SAPS II, Encourage, SAVE, and ACEF scores were calculated. Their ability to predict outcomes were assessed. RESULTS: Indications for ECMO support included postcardiotomy shock (25%), ischemic etiologies (39%), and other etiologies (36%). Pre-ECMO arrest occurred in 73% and 41% of patients underwent cannulation during arrest. Survival to discharge was 39%. Three survival prediction model scores were significantly higher in nonsurvivors to discharge than surivors; the Encourage score (25.4 vs 20; p = .04), the APACHE II score (23.6 vs 19.2; p = .05), and the ACEF score (3.1 vs 1.8; p = .03). In ROC analysis, the ACEF score demonstrated the greatest predictive ability with an AUC of 0.7. CONCLUSIONS: A variety of survival prediction model scores designed for critically ill ICU and VA-ECMO patients demonstrated modest discriminatory ability in the current cohort of patients. The ACEF score, while not designed to predict survival in critically ill patients, demonstrated the best discriminatory ability. Furthermore, it is the simplest to calculate, an advantage in the emergent setting.

A Simple Scoring System to Predict Survival after Venoarterial Extracorporeal Membrane Oxygenation.

Patients undergoing consideration for venoarterial extracorporeal membrane oxygenation (VA ECMO) require an immediate risk profile assessment in the setting of incomplete or no information. A retrospective cohort study of 100 patients undergoing VA ECMO placement at three institutions was carried out. Variables strongly associated with survival to discharge were used to calculate a risk stratification score. Indications for VA ECMO support included postcardiotomy shock (24%), ischemic etiologies (33%), nonischemic cardiomyopathy (32%), and other etiologies (11%). Pre-VA ECMO arrest occurred in 69%, and 30% of patients underwent cannulation during arrest. Survival to discharge was 38%. Three variables demonstrated a strong trend toward predicting survival to discharge: lactate >10 mmol/L (p = .054), albumin <3 g/dL (p = .062), and platelet count <180 K/uL (p = .064), and these variables were included in a scoring system. The extremes of age and duration of pre-VA ECMO ventilation were associated with a dismal prognosis and were also included. These five variables were used to construct a mortality prediction score. A score of 0 was associated with 10% expected mortality, whereas a score of 4+ was associated with 100% expected mortality. Mortality increased in a stepwise fashion with increasing scores. The expected mortality closely paralleled the observed mortality. A simple scoring system composed of easily collected variables may help predict mortality. However, it is not intended to replace an experienced clinician's judgment, but to enhance it.

Distal Perfusion Cannulation and Limb Complications in Venoarterial Extracorporeal Membrane Oxygenation.

The utility of distal perfusion cannula (DPC) placement for the prevention of limb complications in patients undergoing femoral venoarterial (VA) extracorporeal membrane oxygenation (ECMO) is poorly characterized. Patients undergoing femoral VA ECMO cannulation at two institutions were retrospectively assessed. Patients were grouped into those who did and those who did not receive a DPC at the time of primary cannulation. The primary outcome was any limb complication. Secondary outcomes included successfully weaning ECMO and in-hospital mortality. A total of 75 patients underwent femoral cannulation between December 2010 and December 2017. Of those, 65 patients (86.7%) had a DPC placed during primary cannulation and 10 patients (13.3%) did not. Baseline demographics, indications for ECMO, and hemodynamic perturbations were well matched between groups. The rate of limb complications was 14.7% (11/75) for the overall cohort and did not differ between groups (p = .6). Three patients (4%) required a four-compartment fasciotomy for compartment syndrome in the DPC group; no patients without a DPC required fasciotomy. Of the three patients who required a thrombectomy for distal ischemia, two were in the DPC group and one was in the no-DPC group (p = .3). Two patients (2.7%) underwent delayed DPC placement for limb ischemia with resolution of symptoms. The in-hospital morality rate was 59.5% and did not differ between groups (p = .5). Patients in the present study, undergoing femoral VA ECMO without preemptive DPC placement did not experience a higher rate of limb complications. However, the two patients who underwent delayed DPC placement for post-cannulation ischemia experienced resolution of symptoms, suggesting that a DPC may be used as an effective limb salvage intervention.