Abdominal hypertension and decompression: the effect on peritoneal metabolism in an experimental porcine study.

OBJECTIVE: The aim of this study was to investigate the abdominal metabolic response and circulatory changes after decompression of intra-abdominal hypertension in a porcine model. METHODS: This was an experimental study with controls. Three-month-old domestic pigs of both sexes were anesthetized and ventilated. Nine animals had a pneumoperitoneum-induced IAH of 30 mmHg for 6 hours. Twelve animals had the same IAH for 4 hours followed by decompression, and were monitored for another 2 hours. Hemodynamics, including laser Doppler-measured mucosal blood flow, urine output, and arterial blood samples were analyzed every hour along with glucose, glycerol, lactate and pyruvate concentrations, and lactate-pyruvate (l/p) ratio, measured by microdialysis. RESULTS: Laser Doppler-measured mucosal blood flow and urine output decreased with the induction of IAH and showed a statistically significant resolution after decompression. Both groups developed distinct metabolic changes intraperitoneally on induction of IAH, including an increased l/p ratio, as signs of organ hypoperfusion. In the decompression group the intraperitoneal l/p ratio normalized during the second decompression hour, indicating partially restored perfusion. CONCLUSION: Decompression after 4 hours of IAH results in an improved intestinal blood flow and a normalized intraperitoneal l/p ratio.

Intra-peritoneal microdialysis and intra-abdominal pressure after endovascular repair of ruptured aortic aneurysms.

OBJECTIVES: This study aims to evaluate intra-peritoneal (ip) microdialysis after endovascular aortic repair (EVAR) of ruptured abdominal aortic aneurysm (rAAA) in patients developing intra-abdominal hypertension (IAH), requiring abdominal decompression. DESIGN: Prospective study. MATERIAL AND METHODS: A total of 16 patients with rAAA treated with an emergency EVAR were followed up hourly for intra-abdominal pressure (IAP), urine production and ip lactate, pyruvate, glycerol and glucose by microdialysis, analysed only at the end of the study. Abdominal decompression was performed on clinical criteria, and decompressed (D) and non-decompressed (ND) patients were compared. RESULTS: The ip lactate/pyruvate (l/p) ratio was higher in the D group than in the ND group during the first five postoperative hours (mean 20 vs. 12), p = 0.005 and at 1 h prior to decompression compared to the fifth hour in the ND group (24 vs. 13), p = 0.016. Glycerol levels were higher in the D group during the first postoperative hours (mean 274.6 vs. 121.7 µM), p = 0.022. The IAP was higher only at 1 h prior to decompression in the D group compared to the ND group at the fifth hour (mean 19 vs. 14 mmHg). CONCLUSIONS: Ip l/p ratio and glycerol levels are elevated immediately postoperatively in patients developing IAH leading to organ failure and subsequent abdominal decompression.

Complete replacement of open repair for ruptured abdominal aortic aneurysms by endovascular aneurysm repair: a two-center 14-year experience.

OBJECTIVE: To present the combined 14-year experience of 2 university centers performing endovascular aneurysm repair (EVAR) on 100% of noninfected ruptured abdominal aortic aneurysms (RAAA) over the last 32 months. BACKGROUND: Endovascular aneurysm repair for RAAA feasibility is reported to be 20% to 50%, and EVAR for RAAA has been reported to have better outcomes than open repair. METHODS: We retrospectively analyzed prospectively gathered data on 473 consecutive RAAA patients (Zurich, 295; Örebro, 178) from January 1, 1998, to December 31, 2011, treated by an "EVAR-whenever-possible" approach until April 2009 (EVAR/OPEN period) and thereafter according to a "100% EVAR" approach (EVAR-ONLY period).Straightforward cases were treated by standard EVAR. More complex RAAA were managed during EVAR-ONLY with adjunctive procedures in 17 of 70 patients (24%): chimney, 3; open iliac debranching, 1; coiling, 8; onyx, 3; and chimney plus onyx, 2. RESULTS: Since May 2009, all RAAA but one have been treated by EVAR (Zurich, 31; Örebro, 39); 30-day mortality for EVAR-ONLY was 24% (17 of 70). Total cohort mortality (including medically treated patients) for EVAR/OPEN was 32.8% (131 of 400) compared with 27.4% (20 of 73) for EVAR-ONLY (P = 0.376). During EVAR/OPEN, 10% (39 of 400) of patients were treated medically compared with 4% (3 of 73) of patients during EVAR-ONLY. In EVAR/OPEN, open repair showed a statistically significant association with 30-day mortality (adjusted odds ratio [OR] = 3.3; 95% confidence interval [CI], 1.4-7.5; P = 0.004). For patients with no abdominal decompression, there was a higher mortality with open repair than EVAR (adjusted OR = 5.6; 95% CI, 1.9-16.7). In patients with abdominal decompression by laparotomy, there was no difference in mortality (adjusted OR = 1.1; 95% CI, 0.3-3.7). CONCLUSIONS: The "EVAR-ONLY" approach has allowed EVAR treatment of nearly all incoming RAAA with low mortality and turndown rates. Although the observed association of a higher EVAR mortality with abdominal decompression needs further study, our results support superiority and more widespread adoption of EVAR for the treatment of RAAA.

The use of aortic balloon occlusion in traumatic shock: first report from the ABO trauma registry.

PURPOSE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a technique for temporary stabilization of patients with non-compressible torso hemorrhage. This technique has been increasingly used worldwide during the past decade. Despite the good outcomes of translational studies, clinical studies are divided. The aim of this multicenter-international study was to capture REBOA-specific data and outcomes. METHODS: REBOA practicing centers were invited to join this online register, which was established in September 2014. REBOA cases were reported, both retrospective and prospective. Demographics, injury patterns, hemodynamic variables, REBOA-specific data, complications and 30-days mortality were reported. RESULTS: Ninety-six cases from 6 different countries were reported between 2011 and 2016. Mean age was 52 ± 22 years and 88% of the cases were blunt trauma with a median injury severity score (ISS) of 41 (IQR 29-50). In the majority of the cases, Zone I REBOA was used. Median systolic blood pressure before balloon inflation was 60 mmHg (IQR 40-80), which increased to 100 mmHg (IQR 80-128) after inflation. Continuous occlusion was applied in 52% of the patients, and 48% received non-continuous occlusion. Occlusion time longer than 60 min was reported as 38 and 14% in the non-continuous and continuous groups, respectively. Complications, such as extremity compartment syndrome (n = 3), were only noted in the continuous occlusion group. The 30-day mortality for non-continuous REBOA was 48%, and 64% for continuous occlusion. CONCLUSIONS: This observational multicenter study presents results regarding continuous and non-continuous REBOA with favorable outcomes. However, further prospective studies are needed to be able to draw conclusions on morbidity and mortality.

3D Image Fusion to Localise Intercostal Arteries During TEVAR.

PURPOSE: Preservation of intercostal arteries during thoracic aortic procedures reduces the risk of post-operative paraparesis. The origins of the intercostal arteries are visible on pre-operative computed tomography angiography (CTA), but rarely on intra-operative angiography. The purpose of this report is to suggest an image fusion technique for intra-operative localisation of the intercostal arteries during thoracic endovascular repair (TEVAR). TECHNIQUE: The ostia of the intercostal arteries are identified and manually marked with rings on the pre-operative CTA. The optimal distal landing site in the descending aorta is determined and marked, allowing enough length for an adequate seal and attachment without covering more intercostal arteries than necessary. After 3D/3D fusion of the pre-operative CTA with an intra-operative cone-beam CT (CBCT), the markings are overlaid on the live fluoroscopy screen for guidance. The accuracy of the overlay is confirmed with digital subtraction angiography (DSA) and the overlay is adjusted when needed. Stent graft deployment is guided by the markings. The initial experience of this technique in seven patients is presented. RESULTS: 3D image fusion was feasible in all cases. Follow-up CTA after 1 month revealed that all intercostal arteries planned for preservation, were patent. None of the patients developed signs of spinal cord ischaemia. CONCLUSION: 3D image fusion can be used to localise the intercostal arteries during TEVAR. This may preserve some intercostal arteries and reduce the risk of post-operative spinal cord ischaemia.

A small case series of aortic balloon occlusion in trauma: lessons learned from its use in ruptured abdominal aortic aneurysms and a brief review.

BACKGROUND: EndoVascular and Hybrid Trauma Management (EVTM) is an emerging concept for the early treatment of trauma patients using aortic balloon occlusion (ABO), embolization agents and stent grafts to stop ongoing traumatic bleeding. These techniques have previously been implemented successfully in the treatment of ruptured aortic aneurysm. AIMS: We describe our very recent experience of EVTM using ABO in bleeding patients and lessons learned over the last 20 years from the endovascular treatment of ruptured abdominal aortic aneurysms (rAAA). We also briefly describe current knowledge of ABO usage in trauma. METHODS: A small series of educational cases in our hospital is described, where endovascular techniques were used to gain temporary hemorrhage control. The methods used for rAAA and their applicability to EVTM with a multidisciplinary approach are presented. RESULTS: Establishing femoral arterial access immediately on arrival at the emergency room and use of an angiography table in the surgical suite may facilitate EVTM at an early stage. ABO may be an effective method for the temporary stabilization of severely hemodynamically unstable patients with hemorrhagic shock, and may be useful as a bridge to definitive treatment of the bleeding patients. CONCLUSION: EVTM, including the usage of ABO, can be initiated on patient arrival and is feasible. Further data need to be collected to investigate proper indications for ABO, best clinical usage, results and potential complications. Accordingly, the ABOTrauma Registry has recently been set up. Existing experiences of EVTM and lessons from the endovascular treatment of rAAA may be useful in trauma management.

One hundred percent of ruptured aortic abdominal aneurysms can be treated endovascularly if adjunct techniques are used such as chimneys, periscopes and embolization.

Observational studies comparing endovascular aneurysm repair (EVAR) with open repair (OR) in ruptured abdominal aortic aneurysms (AAA) have suggested a benefit for EVAR but have been questioned recently by randomized controlled trials (RCT). A low eligibility for endovascular repair is a main limitation of these RCTs. In contrast, data from 473 patients from 1998 to 2011 in the Örebro/Zurich series show that nearly all AAA patients presenting with rupture can in fact be treated with EVAR with a low 30-day mortality rate (24%) and a minimal exclusion rate (4%). By using different adjunct techniques, such as chimneys and periscopes, also juxtarenal aneurysms can be treated even if simultaneous aortic balloon occlusion is necessary. OnyxTM embolization of the internal iliac artery in patients with aortoiliac aneurysms prevents back flow, thus avoiding an endoleak type. From May 2009 until December 2013, 70 patients arrived at Örebro University Hospital with a ruptured AAA diagnose. Nine percent were considered unfit for any intervention (including OR) and were treated medically. All of the 64 patients that underwent surgery were treated with EVAR and 30-day mortality in this group was 17 of 64 patients (27%). The mortality for patients treated with adjunct techniques was not significantly increased compared with patients treated with standard EVAR. In conclusion, our data support that open repair of ruptured AAA can be replaced by EVAR with appropriate management of existing adjunct techniques.

Naloxone and haemorrhagic hypotension in rats. Evidence against sympathetic nervous system as the primary mediator of improved cardiovascular haemodynamics.

Release of endogenous opiate-like substances seem to occur in different forms of stress. Earlier studies have shown that the opiate antagonist, naloxone, has a positive effect on cardiac performance and blood pressure in animals with haemorrhagic shock. In the present study, we have examined the involvement of the sympathetic nervous system in this response. Two groups of anaesthetized normotensive Wistar-Kyoto rats were studied. Both groups were bled rapidly (about 5 min) down to an arterial pressure of 50 mmHg and were kept at that level for 30 min. At the end of the 30-min bleeding period, naloxone 1, 2, or 5 mg kg-1 was injected i.v. in a small volume of saline. In the first group of rats (n = 6), the aortic pressure was kept constant at 50 mmHg by further bleedings after naloxone. In the other group (n = 7), the arterial pressure was allowed to rise after naloxone. As reported earlier, haemorrhagic hypotension caused a pronounced inhibition of renal sympathetic nerve activity. Naloxone injected after 30 min of hypotension caused an immediate rise in blood pressure, followed 1-2 min later by a rise in sympathetic nerve activity (SNA). In animals in which pressure was held constant by further bleeding after naloxone, only small and insignificant changes in SNA were observed. The conclusions are the following: injection of naloxone increases blood pressure in rats exposed to severe haemorrhage (Faden & Holiday 1979). The rise in aortic pressure is followed 1-2 min later by a rise in SNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in renal sympathetic outflow during hypotensive haemorrhage in rats.

The goal of this study was to investigate changes in renal sympathetic outflow during hypotensive haemorrhage. Normotensive Wistar-Kyoto rats were anaesthetized with chloralose (50 mg kg-1) and bled to an arterial blood pressure of 50 mmHg for 30 min. Changes in heart rate (HR) and renal nerve activity (RNA) were registered. The hypotensive haemorrhage induced a short-lasting sympathetic excitation that was followed within 5-10 min by a powerful sympathetic inhibition and bradycardia. The average maximal decrease in sympathetic activity was 65% and the maximal decrease in heart rate was 45 beats min-1. There was a close correlation between changes in heart rate and renal sympathetic activity. The marked depressor response was due at least in part to activation of vagal afferents because the depressor responses were acutely reversed by bilateral cervical vagotomy. As cardiac afferents are known to be activated by prostaglandins and bradykinins, and these agents are released by myocardial ischaemia, haemorrhage was repeated after use of indomethacin and aprotinin (a protein inhibitor decreasing bradykinin formation), and a marked sympathetic inhibition could still be elicited upon haemorrhage. We therefore suggest that the likely mechanism for activation of the vagal afferents is a squeezing of the myocardium when the heart has to contract around an almost empty chamber. In conclusion, this study demonstrated that hypotensive haemorrhage triggers profound inhibition of RNA in rats and that this sympathoinhibition is mediated primarily by mechanically sensitive cardiac vagal afferents.

Optimal felodipine dose when combined with metoprolol in arterial hypertension: a Swedish multicenter study within primary health care. Swedish General Practitioner Felodipine Study Group.

In a multicenter study comprising 23 Swedish primary health care centers, felodipine extended-release (ER) tablets in doses of 5, 10, and 20 mg were compared double-blind with placebo when given in addition to metoprolol controlled-release (CR) tablets 100 mg. All medication was given once daily in the morning. Altogether, 251 hypertensive patients with a diastolic blood pressure greater than 95 mm Hg after 4 weeks of treatment with placebo in combination with metoprolol CR 100 mg were randomized to four parallel groups. After 4 weeks of treatment, there were significantly greater reductions in blood pressure with all doses of felodipine ER than with placebo, both 2 and 24 h after intake of the tablets. Twelve patients were withdrawn because of adverse reactions. Of these, one patient was taking placebo, one 5 mg of felodipine ER, four 10 mg of felodipine ER, and six patients 20 mg of felodipine ER. When combined with metoprolol, 5 mg of felodipine ER seemed to be less effective than higher doses, but was very well tolerated. Adding 10 mg of felodipine ER to the basal metoprolol appeared to be optimal if both the effect and adverse reactions were taken into consideration.