A Mortality Prediction Score for Patients With Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO): The PREDICT VV-ECMO Score

Mortality prediction for patients with the severe acute respiratory distress syndrome (ARDS) supported with veno-venous extracorporeal membrane oxygenation (VV-ECMO) is challenging. Clinical variables at baseline and on day 3 after initiation of ECMO support of all patients treated from October 2010 through April 2020 were analyzed. Multivariate logistic regression analysis was used to identify score variables. Internal and external (Monza, Italy) validation was used to evaluate the predictive value of the model. Overall, 272 patients could be included for data analysis and creation of the PREDICT VV-ECMO score. The score comprises five parameters (age, lung fibrosis, immunosuppression, cumulative fluid balance, and ECMO sweep gas flow on day 3). Higher score values are associated with a higher probability of hospital death. The score showed favorable results in derivation and external validation cohorts (area under the receiver operating curve, AUC derivation cohort 0.76 [95% confidence interval, CI, 0.71-0.82] and AUC validation cohort 0.74 [95% CI, 0.67-0.82]). Four risk classes were defined: I ≤ 30, II 31-60, III 61-90, and IV ≥ 91 with a predicted mortality of 28.2%, 56.2%, 84.8%, and 96.1%, respectively. The PREDICT VV-ECMO score suggests favorable performance in predicting hospital mortality under ongoing ECMO support providing a sound basis for further evaluation in larger cohorts.

The "ZEEP-PEEP test" to evaluate the response to positive end-expiratory pressure delivered by helmet: A prospective physiologic study

Introduction

The improvement in oxygenation after helmet application in hypoxemic patients may be explained by the alveolar recruitment obtained with positive end expiratory pressure (PEEP) or by the administration of a more accurate inspiratory fraction of oxygen (FiO2). We have designed the "ZEEP-PEEP test", capable to distinguish between the FiO2-related or PEEP-related oxygenation improvement. Our primary aim was to describe the use of this test during helmet CPAP to assess the oxygenation improvement attributable to PEEP application.

Material and methods

We performed a prospective physiological study including adult critically ill patients. Respiratory and hemodynamic parameters were recorded before helmet application (PRE step), after helmet application without PEEP (ZEEP step) and after the application of the PEEP valve (PEEP step), while maintaining a constant FiO2. We defined as "PEEP responders" patients showing a PaO2/FiO2 ratio improvement ≥10% after PEEP application.

Results

93 patients were enrolled. Compared to the PRE step, PaO2/FiO2 ratio was significantly improved during helmet CPAP both at ZEEP and PEEP step (189 ± 55, 219 ± 74 and 241 ± 82 mmHg, respectively, p < 0.01). Both PEEP responders (41%) and non-responders showed a significant improvement of PaO2/FiO2 ratio after the application of helmet at ZEEP, PEEP responders also showed a significant improvement of oxygenation after PEEP application (208 ± 70 vs 267 ± 85, p < 0.01).

Conclusions

Helmet CPAP improved oxygenation. This improvement was not only due to the PEEP effect, but also to the increase of the effective inspired FiO2. Performing the ZEEP-PEEP test may help to identify patients who benefit from PEEP.

Midline catheters for blood gas and acid/base monitoring in critical patients: A prospective observational study

Background:

Arterial lines and central venous catheter (CVC) allow to monitor patients’ acid-base status and gas exchange. Their placement and maintenance may however be burdened by severe complications. Midline Catheters (MC) are peripheral venous accesses that are less invasive and easier to insert compared to CVC and arterial lines.

Methods:

A prospective observational study was performed including stabilized critical patients with clinical indication to midline positioning before intensive care unit (ICU) discharge. The primary aim was to assess if venous sampling from MCs can be a reliable alternative to CVC for pH and CO2 monitoring. The secondary aim was to evaluate the correlation between samplings from MC, CVC and arterial line with regards to pH, carbon dioxide tension (pCO2), lactates and electrolytes. Three samples from CVC, arterial line and MC were collected simultaneously. Agreement and correlation of the studied parameters between different sampling sites were explored.

Results:

40 patients were included in the analysis. A good agreement for pH and pCO2 was recorded between MC and CVC: mean differences were 0.001 (95% CI −0.006 to 0.007) and 0.7 (−0.1 to 1.5), percentage error 0.4% and 11.2%, respectively. Correlation between MC and both central venous and arterial samples for pH, pCO2, lactates and electrolytes was found to be moderate-to-strong (Pearson’s R coefficient range 0.59–0.99, p < 0.001 for all these parameters).

Conclusions:

In stabilized critical patients, midline catheters represent a reliable alternative to CVC and arterial lines to monitor acid-base disturbances, CO2 levels and electrolytes. The present findings add to the known advantages of MC, which might be considered a first-line vascular access for non-critical or stabilized patients who do not require infusion of vesicant or irritant drugs.

Role of Complete Duplex Ultrasound to Diagnose Deep Vein Thrombosis in COVID-19 Critical Patients

An increased risk of deep vein thrombosis (DVT) has been reported in critical COVID-19 patients, despite adequate thromboprophylaxis, and most of DVT are probably asymptomatic. As a screening approach has been advocated, the best examination protocol is unknown. The objective of this study is to assess the role of a Complete Duplex Ultrasound (CDUS) examination in detecting DVT in a large population of COVID-19 patients admitted to intensive care unit (ICU) for respiratory failure. Single-center retrospective study of 145 COVID-19 patients admitted to ICU. DVT was assessed with a CDUS performed by experienced radiologist after ICU admission. DVT was confirmed in 38 patients (26%). Most DVT were distal to the knee (66%), while only 16% were proximal. At the time of the examination, 55% of the patients received full-dose anticoagulation, while 45% received thromboprophylaxis, and there were no differences in anticoagulation regimen between positive and negative patients. Patients with DVT had higher dimers compared with those with negative CDUS (P < .002). The observed frequency of DVT is high despite adequate anticoagulation. A comprehensive and experienced ultrasound examination protocol can allow to recognize a large number of distal DVT otherwise missed, albeit their clinical significance is unknown.

Volatile Sedation for Acute Respiratory Distress Syndrome Patients on Venovenous Extracorporeal Membrane Oxygenation and Ultraprotective Ventilation

Supplemental Digital Content is available in the text.

Patients on extracorporeal support for severe acute respiratory distress syndrome may require a prolonged period of deep sedation. In these patients, volatile sedation may represent a valid alternative to IV drugs. The aim of our study was to describe the feasibility of volatile sedation in a large cohort of acute respiratory distress syndrome patients undergoing venovenous extracorporeal membrane oxygenation and ultraprotective ventilation.

[Performance studies of 6 new anesthesia ventilators: bench tests]

OBJECTIVE

To assess the pneumatic performances of six new anaesthesia ventilators.

STUDY DESIGN

Bench test study.

MATERIAL

The study included one ventilator operated by an electric motor: ABT 5300 (Kontron); four ventilators of "bellows-in-bottle" category: ADU version 97 (Datex-Ohmeda); Aestiva 3000 (Datex-Ohmeda), Kion (Siemens), the two versions of Julian (Dräger); and an original ventilator devised for quantitative, or self-regulating target controlled inhalation anaesthesia, with a totally closed circuit, made of four ventilating chambers: PhysioFlex (Dräger).

METHODS

The bench test included a passive lung model with adjustable compliance and resistances, and flow and pressure gauges. The accuracy of volume and pressure measurements was tested in various conditions of resistance and compliance.

RESULTS

Pneumatic performance and accuracy were satisfactory, even in severe ventilatory conditions. All the ventilators, except ABT 5300 and Julian 1, have a compliance compensation system permitting to deliver and to maintain a constant tidal volume under various conditions of downstream load, particularly under maximal load condition. Variations of tidal volume with the increase of the fresh gas flow are negligible.

CONCLUSION

Recent technological progress has improved pneumatic performance of anaesthesia ventilators and the marketed models are more homogeneous at present. Ergonomics and training for the use of the machine are becoming major criteria for the global assessment and the choice of a ventilator.