Use of a disposable vascular pressure device to guide balloon inflation of resuscitative endovascular balloon occlusion of the aorta: a bench study

Resuscitative endovascular balloon occlusion of the aorta (REBOA) for rapid hemorrhage control is increasingly being used in trauma management. Its beneficial hemodynamic effects on unstable patients beyond temporal hemostasis has led to growing interest in its use in other patient populations, such as during cardiac arrest from nontraumatic causes. The ability to insert the catheters without fluoroscopic guidance makes the technique available in the prehospital setting. However, in addition to correct positioning, challenges include reliably achieving aortic occlusion while minimizing the risk of balloon rupture. Without fluoroscopic control, inflation of the balloon relies on estimated aortic diameters and on the disappearing pulse in the contralateral femoral artery. In the case of cardiac arrest or absent palpable pulses, balloon inflation is associated with excess risk of overinflation and adverse events (vessel damage, balloon rupture). In this bench study, we examined how the pressure in the balloon is related to the surrounding blood pressure and the balloon's contact with the vessel wall in two sets of experiments, including a pulsatile circulation model. With this data, we developed a rule of thumb to guide balloon inflation of the ER-REBOA catheter with a simple disposable pressure-reading device (COMPASS). We recommend slowly filling the balloon with saline until the measured balloon pressure is 160 mmHg, or 16 mL of saline have been used. If after 16 mL the balloon pressure is still below 160 mmHg, saline should be added in 1-mL increments, which increases the pressure target about 10 mmHg at each step, until the maximum balloon pressure is reached at 240 mmHg (= 24 mL inflation volume). A balloon pressure greater than 250 mmHg indicates overinflation. With this rule and a disposable pressure-reading device (COMPASS), ER-REBOA balloons can be safely filled in austere environments where fluoroscopy is unavailable. Pressure monitoring of the balloon allows for recognition of unintended deflation or rupture of the balloon.

A bench-to-bedside study about trigger asynchronies induced by the introduction of external gas into the non-invasive mechanical ventilation circuit

Treatments that require the introduction of external gas into the non-invasive ventilation (NIV) circuit, such as aerosol and oxygen therapy, may influence the performance of the ventilator trigger system. The aim of the study was to determine the presence and type of asynchronies induced by external gas in the NIV circuit in a bench model and in a group of patients undergoing chronic NIV. Bench study: Four ventilators (one with two different trigger design types) and three gas sources (continuous flow at 4 and 9 l/min and pulsatile flow at 9 l/min) were selected in an active simulator model. The sensitivity of the trigger, the gas introduction position, the ventilatory pattern and the level of effort were also modified. The same ventilators and gas conditions were used in patients undergoing chronic NIV. Bench: the introduction of external gas caused asynchronies in 35.9% of cases (autotriggering 73%, ineffective effort 27%). Significant differences (p < 0.01) were detected according to the ventilator model and the gas source. In seven patients, the introduction of external gas induced asynchrony in 20.4% of situations (77% autotriggering). As in the bench study, there were differences in the occurrence of asynchronies depending on the ventilator model and gas source used. The introduction of external gas produces alterations in the ventilator trigger. These alterations are variable, and depend on the ventilator design and gas source. This phenomenon makes it advisable to monitor the patient at the start of treatment.

Trigger Asynchronies Induced by the Introduction of External Gas Into the Non-Invasive Mechanical Ventilation Circuit: A Bench-to-Bedside Study

Background and objective: Treatments that require the introduction of external gas into the non-invasive ventilation (NIV) circuit, such as aerosol and oxygen therapy, may influence the performance of the ventilator trigger system. The aim of the study was to determine the presence and type of asynchronies induced by external gas in the NIV circuit in a bench model and in a group of patients undergoing chronic NIV.Methods: Bench study: Four ventilators (one with two different trigger design types) and three gas sources (continuous flow at 4 and 9 l/min and pulsatile flow at 9 l/min) were selected in an active simulator model. The sensitivity of the trigger, the gas introduction position, the ventilatory pattern and the level of effort were also modified.Clinical study: The same ventilators and gas conditions were used in patients undergoing chronic NIV.Results: Bench: The introduction of external gas caused asynchronies in 35.9% of cases (autotriggering 73%, ineffective effort 27%). Significant differences (p<0.01) were detected according to the ventilator model and the gas source.Clinical study: In seven patients, the introduction of external gas induced asynchrony in 20.4% of situations (77% autotriggering). As in the bench study, there were differences in the occurrence of asynchronies depending on the ventilator model and gas source used.Conclusion: The introduction of external gas produces alterations in the ventilator trigger. These alterations are variable, and depend on the ventilator design and gas source. This phenomenon makes it advisable to monitor the patient at the start of treatment.