Temporary arterial shunting is an established method to prevent tissue ischaemia. Although less well established, shunting might also be achieved through endovascular and hybrid techniques, known as ...endoshunting. Endoshunting offers advantages, for example, enabling minimally invasive access and avoiding complete occlusion of the donor artery. In an ex vivo bench test, volume flow in various interconnected endoshunt systems has been tested previously. This study aimed to investigate the capacity of the best performing endoshunt system in vivo.
Six anaesthetised pigs had their common iliac arteries (CIAs) explored, with the left CIA serving as the experimental and the right CIA as the control. Mean arterial pressure, regional blood flow, endoshunt flow, and regional oxygen extraction and lactate production were recorded. Distal muscle perfusion was monitored using near infrared spectroscopy (NIRS). Each experiment involved baseline registration, cross clamping of the left CIA, a 120 minute endoshunt session, and restoration of native flow.
During cross clamping, NIRS values on the experimental side reached the lowest measurable value. Following endoshunt activation, there were no NIRS value differences between the experimental and control extremities whereas the average arterial flow decreased in both the experimental (270–140 mL/min, p = .028) and control extremities (245–190 mL/min, p = .25), with a greater drop on the endoshunted side (48% vs. 22%, respectively). Lactate levels temporarily increased by 42% in the endoshunted limb on endoshunt activation but were normalised within an hour. Oxygen extraction remained constant at 55% on the control side but increased to 70% on the endoshunted side (p = .068).
In this animal model, a flow optimised endoshunt system appeared to provide sufficient blood flow and restored stable tissue perfusion. Although arterial flow was slightly lower and oxygen extraction slightly higher on the endoshunted side, the endoshunt seemed to deliver adequate perfusion to prevent significant ischaemia.
•Endoshunting is an alternative to conventional arterial shunting.•This study investigated the performance of a flow optimised endoshunt in vivo.•The endoshunt delivered sufficient tissue perfusion to avoid significant ischaemia.•Endoshunting may be used in various clinical situations to avoid distal ischaemia.
Acute tissue ischaemia may arise due to arterial emergencies or during more complex vascular procedures and may be mitigated by temporary shunting techniques. Endovascular shunting (ES) techniques ...enable percutaneous access and shunting from the donor artery without the need to completely interrupt the arterial flow in the donor artery. An endoshunt system may also cover longer distances than most conventional shunts. The aim was to investigate and optimise the flow rates in different endovascular shunt systems.
Step 1: The flow capacity of different ES configurations was compared with the flow capacity of a 9 Fr Pruitt–Inahara shunt (PIS). An intravenous bag with 0.9% NaCl, pressurised to 90 mmHg, was connected simultaneously to a PIS and to one of the tested ES configurations. The two shunt systems were then opened at the same time. The delivered fluid volumes from the shunt systems were collected and measured. The volume flow rate was subsequently calculated. Steps 2 and 3: Within a heart lung machine circuit, pressure–flow charts were constructed for the individual ES components and for the fully connected optimised endoshunt systems. The flow rate was increased in steps of 40–50 mL/min while monitoring the driving pressure, enabling the creation and comparison of the pressure–flow charts for the individually tested components. In total, seven individual inflow and outflow potential ES components were investigated with inflow and outflow diameters ranging from 6 to 15 Fr.
ES systems based on standard donor introducers led to substantially lower volume flow than the corresponding PIS volume flow, whereas ES systems based on dedicated 6 or 8 Fr dialysis access introducers (Prelude Short Sheath, Merit Medical) matched PIS flow rates. The introduction of 30 cm long ¼′′ perfusion tubing within the ES system did not affect volume flow for any of the tested ES configurations.
Endoshunting techniques can match PIS volume flow rates over short and long distances. The achieved ES flow rate is highly dependent on the components used within the ES system.
Acute tissue ischaemia may arise due to arterial emergencies or during more complex vascular procedures and may be mitigated by temporary shunting techniques. Endovascular shunting (ES) techniques ...enable percutaneous access and shunting from the donor artery without the need to completely interrupt the arterial flow in the donor artery. An endoshunt system may also cover longer distances than most conventional shunts. The aim was to investigate and optimise the flow rates in different endovascular shunt systems.
Step 1: The flow capacity of different ES configurations was compared with the flow capacity of a 9 Fr Pruitt–Inahara shunt (PIS). An intravenous bag with 0.9% NaCl, pressurised to 90 mmHg, was connected simultaneously to a PIS and to one of the tested ES configurations. The two shunt systems were then opened at the same time. The delivered fluid volumes from the shunt systems were collected and measured. The volume flow rate was subsequently calculated. Steps 2 and 3: Within a heart lung machine circuit, pressure–flow charts were constructed for the individual ES components and for the fully connected optimised endoshunt systems. The flow rate was increased in steps of 40–50 mL/min while monitoring the driving pressure, enabling the creation and comparison of the pressure–flow charts for the individually tested components. In total, seven individual inflow and outflow potential ES components were investigated with inflow and outflow diameters ranging from 6 to 15 Fr.
ES systems based on standard donor introducers led to substantially lower volume flow than the corresponding PIS volume flow, whereas ES systems based on dedicated 6 or 8 Fr dialysis access introducers (Prelude Short Sheet, Merit Medical) matched PIS flow rates. The introduction of 30 cm long ¼′′ perfusion tubing within the ES system did not affect volume flow for any of the tested ES configurations.
Endoshunting techniques can match PIS volume flow rates over short and long distances. The achieved ES flow rate is highly dependent on the components used within the ES system.
•Endovascular shunting techniques have emerged as versatile approaches to manage ischaemia during vascular emergencies and procedures but remain poorly studied.•In this study the flow rates in different endovascular shunt systems were investigated. Flow capacity differences were noted both between individual devices and different endoshunt systems.•Only optimised endoshunt circuits matched or outperformed the corresponding flow capacity of a commercially available conventional vascular shunt.•These observations may guide vascular surgeons to select more optimised endoshunting approaches that ultimately may limit end organ damage in many clinical scenarios.
Both greenhouse gas (GHG) emissions and local emissions from heavy duty (HD) Diesel engines must be greatly reduced to make transportation sustainable and comply with increasingly stringent emissions ...regulations. The fuel flexible engine concept for HD Diesel engines uses a dual fuel direct injection system in which ignition of the main alcohol fuel, either methanol or ethanol, is induced by a small Diesel pilot injection delivered via a separate direct injector. The objective of this investigation was to find ways to combine the advantages of conventional Diesel engines with the advantages of low carbon fuels and to thereby bypass the soot-NOx-trade-off. Experiments were conducted using a modified single-cylinder HD engine and three fuels (methanol, ethanol, and a reference Diesel fuel) to determine how the choice of fuel affected the engine’s combustion behaviour, emissions and fuel efficiency. Injection pressures on the alcohol side were varied up to 1500 bar and the investigation was carried out at low, medium and high speed-load points. The alcohol fuels significantly outperformed Diesel fuel under all tested conditions (with and without exhaust gas recirculation (EGR)). Indicated thermal efficiency was increased by up to 3.5%-points and simultaneously soot emissions were lowered by a factor of 40 or more and NOx by 20%. Combustion stability and emissions were in the same range as for Diesel but replacing more than 95 % of the fossil Diesel with an alcohol fuel.
With great interest we read the clinical report regarding the effect of blood pressure on plasma volume (PV), atrial natriuretic peptide (ANP) and glycocalyx by Damén et al.
. Twenty-four patients ...underwent cardiac surgery were divided into two groups, 90 mmHg of mean artery pressure (MAP) (the intervention group) or 60 mmHg of MAP (the control group) by titration of norepinephrine.
We thank Dr Saito for the interest in our paper "Effects of different mean arterial pressure targets on plasma volume, ANP and glycocalyx-A randomized trial" where cardiac surgery patients were ...randomised to a mean arterial pressure (MAP) of 60 or 90 mm Hg using norepinephrine (NE) infusion.
The plasma volume (PV) and the Mid Regional-pro Atrial Natriuretic Peptide (MR-proANP) increased in the group randomised to lower MAP. All patients had a normal left ventricular ejection fraction of 45% or more.
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