pHi monitoring of the sigmoid colon after aortoiliac surgery. A five-year prospective study

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Surveillance to detect colonic ischemia with extraluminal pH measurement after open surgery for abdominal aortic aneurysm

OBJECTIVE

Colonic ischemia (CI) is a life-threatening complication after aortic surgery. Postoperative surveillance of colonic perfusion might be warranted. The aim of the present study was to evaluate the safety and feasibility of postoperative extraluminal pH measurement (pHe) using colonic tonometry after open abdominal aortic aneurysm (AAA) repair.

METHODS

Before closing the abdomen after open AAA repair, a tonometric catheter was placed transabdominally in contact with the sigmoid colon serosa, similar to a drainage catheter. Extraluminal partial pressure of carbon dioxide was measured postoperatively and combined with arterial blood gas analysis to calculate the pHe. The measurements were repeated every 4 hours with simultaneous intra-abdominal pressure measurements. The threshold for colonic malperfusion was set at pHe <7.2.

RESULTS

A total of 27 patients were monitored, 12 had undergone surgery for ruptured AAAs and 15 for intact AAAs. Of the 27 patients, 4 developed clinically significant CI requiring surgery. All four cases were preceded by a prolonged (>5 hours) pHe <7.2 indicating malperfusion. A fifth patient, who, during monitoring, had had the lowest pHe of 7.21, developed mild CI with the onset after completion of monitoring, which was successfully managed conservatively. Seven patients who had had brief durations (<5 hours) of pHe <7.2 did not develop clinical signs of CI or any related adverse events.

CONCLUSIONS

Measurements of pHe using colonic tonometry indicated malperfusion in all four patients who had developed clinically significant CI. A shorter duration of low pHe was well tolerated without any signs of CI. Measurement of pHe was safe and reliable for the surveillance of colonic perfusion after open aortic surgery, indicating a promising technique. However, larger studies are needed.

Perfusion of the gastric conduit during esophagectomy

In esophageal cancer surgery, perfusion of the gastric conduit is a critical issue. Measurement of gastric intramucosal pH (pHi) is a method to identify anaerobic metabolism as a sign of impaired perfusion. In this study we aimed to monitor changes in the perfusion of the gastric conduit at key steps during and after esophagectomy. pHi was measured per- and postoperatively using intermittent gastric tonometry in 32 patients undergoing open, 65%, or video-assisted thoracoscopic esophagectomy for esophageal cancer. Measurements focused on the surgical steps when the vascular supply to the gastric conduit was altered. A tonometry catheter was successfully placed in all patients and a decrease in pHi (mean ± SD) was observed from baseline to after the division of the short gastric vessels (7.33 ± 0.07 to 7.29 ±  0.07, P  = 0.005). A further reduction after the ligation of the left gastric artery (7.26 ± 0.08, P  < 0.001) and after final linear stapling the gastric conduit (7.15 ± 0.13, P  < 0.001) was observed. Two hours after surgery, pHi increased (7.24 ± 0.09, P  = 0.002). In contrast to open surgery, a trend towards less reduction in pHi was seen in thoracoscopic surgery. Patients with anastomotic leaks had lower pHi on the first postoperative day (7.12 ± 0.05 vs. 7.27 ± 0.08, P  = 0.040). It can be concluded that each surgical step altering the vascular supply to the gastric conduit resulted in detectable changes, however transient, in pHi. Patients with low pHi on the first postoperative day were more prone to have clinically relevant anastomotic leaks.

Outcomes of regional transfers of ruptured abdominal aortic aneurysm in a UK vascular network

INTRODUCTION Rupture of abdominal aortic aneurysm is a surgical emergency. In order to improve operative outcomes, vascular services have been centralised in the United Kingdom. This means that a patient may present to a hospital with a ruptured aneurysm, but require transfer to a vascular centre for definitive treatment. METHODS This retrospective cohort study identified patients who underwent surgery for ruptured abdominal aortic aneurysm in a tertiary vascular centre over a 2-year period. Data on demographics and originating unit were recorded. Outcomes assessed included 30-day mortality, operative mortality and postoperative morbidity. RESULTS We identified 70 patients who underwent surgery for ruptured abdominal aortic aneurysm in the 2-year period; 36 presented directly to the vascular unit (VU), 14 to referral unit 1 (RU1) and 20 to referral unit 2 (RU2); 30-day mortality rates were 27.7% (VU), 35.5% (RU1) and 30.0% (RU2), respectively. There was no statistical difference in mortality between units. Postoperative complications were seen in 35.9% of VU patients, 78.6% of RU1 patients and 70% of RU2 patients. This was statistically significant between VU and RU1 (P = 0.006) and VU and RU2 (P = 0.02). Direct operative complications were seen in 9 patients, gastrointestinal complications in 9, limb complications in 6 and systemic complications in 40. CONCLUSION This study found that site of presentation does not affect mortality but is associated with increased morbidity. This is a complex issue, which will require a prospective multicentre study to investigate further.

Risk factors for ischaemic colitis after surgery for abdominal aortic aneurysm: a systematic review and observational meta-analysis

BACKGROUND

Ischaemic colitis is an infrequent but serious complication following repair of abdominal aortic aneurysm (AAA), with high mortality rates. This systematic review set out to identify risk factors for the development of ischaemic colitis after AAA surgery.

METHODS

A systematic search of the MEDLINE, EMBASE and CINAHL databases was performed. This search was limited to studies published in the English language after 1990. Abstracts were screened by two authors. Eligible studies were obtained as full text for further examination. Data was extracted by two authors, and any disputes were resolved via consensus. Extracted data was pooled using Mantel-Haenszel random effects models. Bias was assessed using two Cochrane-approved tools. Effect sizes are expressed as relative risk ratios alongside the 95 % confidence interval. Statistical significance was defined at the level of p < 0.05.

RESULTS

From 388 studies identified in the initial search, 33 articles were included in the final synthesis and analysis. Risk factors were grouped into patient (female gender, disease severity) and operative factors (peri-procedural hypotension, operative modality). The risk of ischaemic colitis was significantly higher when undergoing emergency repair versus elective (risk ratio (RR) 7.36, 3.08 to 17.58, p < 0.001). Endovascular repair reduced the likelihood of ischaemic colitis (RR 0.22, 0.12 to 0.39, p < 0.001).

DISCUSSION

The quality of published evidence on this subject is poor with many retrospective datasets and inconsistent reporting across studies. Despite this, emergency presentation and open repair should prompt close monitoring for the development of IC.

Management of abdominal compartment syndrome and the open abdomen

OBJECTIVES

The management of the abdominal compartment syndrome (ACS) and the open abdomen (OA) are important to improve survival after major vascular surgery, in particular ruptured abdominal aortic aneurysm (RAAA). The aim is to summarize contemporary knowledge in this field.

METHODS

The consensus definitions of the World Society of the Abdominal Compartment Syndrome (WSACS) that were published in 2006 and the clinical practice guidelines published in 2007 were updated in 2013. Structured clinical questions were formulated (modified Delphi method), and the evidence base to answer those questions was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines.

RESULTS

Most of the previous definitions were kept untouched, or were slightly modified. Four new definitions were added, including a definition of OA and of lateralization of the abdominal wall, an important clinical problem to approach during prolonged OA treatment. A classification system of the OA was added. Seven recommendations were formulated, in summary: Trans-bladder intra-abdominal pressure (IAP) should be monitored in patients at risk. Protocolized monitoring and management are recommended, and decompression laparotomy if ACS. When OA, protocolized efforts to obtain an early abdominal fascial closure, and strategies utilizing negative pressure wound therapy should be used, versus not. In most cases the evidence was graded as weak or very weak. In six of the structured clinical questions, no recommendation could be made.

CONCLUSION

This review summarizes changes in definitions and management guidelines of relevance to vascular surgery, and data on the incidence of ACS after open and endovascular aortic surgery.

Early detection of gut ischemia-reperfusion injury during aortic abdominal aneurysmectomy: a pilot, observational study

OBJECTIVE

D-lactate is the enantiomer of L-lactate, which is measured routinely in clinical practice to assess cell hypoxia. D-lactate has been proposed as a specific marker of gut ischemia-reperfusion (IR), particularly during surgery for ruptured abdominal aortic aneurysms. The aim of this study was to compare the use of D-lactate measurement and colonic tonometry (taken as a reference method) for gut IR detection during elective infrarenal aortic aneurysm (IrAA) surgery.

DESIGN

Prospective, monocenter, observational study.

SETTING

Vascular surgery unit, university hospital.

PARTICIPANTS

Candidates for elective IrAA surgery.

INTERVENTIONS

Patients without (controls) and with gut IR (defined as ΔCO2>2.6 kPa) were compared retrospectively.

MEASUREMENT AND MAIN RESULTS

D-lactate levels were compared with colonic perfusion levels (ΔCO2), as assessed by colonic tonometry, at 7 time points during surgery and until 24 hours after surgery. D-lactate also was measured in mesenteric vein blood before and after gut reperfusion. Plasma TNF-α level was measured at the same time points to assess systemic inflammatory response. Eighteen patients requiring elective IrAA surgery were included. The ΔCO2 and TNF-α level varied significantly over time. There was a significant ΔCO2 peak at the end of clamping (2.6±1.8 kPa, p = 0.006) and a significant peak in TNF-α level after 1 hour of reperfusion (183±53 ng/L, p = 0.05). D-lactate levels were undetectable in systemic and mesenteric blood in all the patients throughout the study period. Gut IR patients (n = 6) experienced a longer overall duration of intraoperative hypotensive episodes and received more catecholamines than the controls (n = 12).

CONCLUSIONS

Compared with colonic tonometry, D-lactate was not a reliable biomarker of gut IR during elective IrAA surgery.

Nonocclusive mesenteric hypoperfusion syndromes: recognition and treatment

The main focus when discussing acute or chronic mesenteric ischemia is on occlusive disease, arterial or venous. This article reviews present knowledge on mesenteric nonocclusive hypoperfusion syndromes. The following three clinical entities are reviewed: (1) Intraabdominal hypertension (IAH), or abdominal compartment syndrome (ACS), is important after ruptured abdominal aortic aneurysm repair. IAH >20 mm Hg occurs in approximately 50% of patients after open repair and in 20% after endovascular repair of ruptured abdominal aortic aneurysm, but these patients are different and no randomized data exists yet. A consensus issued by the World Society of Abdominal Compartment Syndrome provides guidance. Early conservative treatment of IAH and, alternatively, abdominal closure devices for leaving the abdomen partially open temporarily are discussed and a treatment algorithm is suggested. (2) Colonic ischemia after abdominal aortic surgery, its risk factors, clinical presentation, and treatment are discussed. A significant number of such patients develop IAH and reducing the abdominal perfusion pressure affects the left colon, the sentinel organ in these patients. (3) Nonocclusive mesenteric ischemia (NOMI); most often such patients suffer from severe cardiac failure requiring massive inotropic support. The condition is difficult to define. Early diagnosis with multidetector row computed tomography is a worthwhile alternative when angiography presents difficulties. A stenosis of the superior mesenteric artery is frequently enough that it should be ruled out because endovascular treatment can be lifesaving. New knowledge on these three different mesenteric hypoperfusion syndromes is reviewed. Success in treating these difficult patients is benefited from a multidisciplinary approach.

Colonic ischaemia and intra-abdominal hypertension following open repair of ruptured abdominal aortic aneurysm

Background

The aim was to investigate the association between colonic ischaemia and intra-abdominal pressure (IAP) after surgery for ruptured abdominal aortic aneurysm (rAAA).

Methods

Sigmoid colon perfusion was monitored with an intramucosal pH (pHi) tonometer. Patients with a pHi of 7·1 or less were treated for suspected hypovolaemia with intravenous colloids and colonoscopy. IAP was measured every 4 h. Patients with an IAP of 20 mmHg or more had neuromuscular blockade, relaparotomy or both.

Results

A total of 52 consecutive patients had open rAAA repair; 30-day mortality was 27 per cent. Eight patients died shortly after surgery. Fifteen were not monitored for practical reasons; mortality in this group was 33 per cent. IAP and pHi were measured throughout the stay in intensive care in the remaining 29 patients. Monitoring led to volume resuscitation in 25 patients, neuromuscular blockade in 16, colonoscopy in 19 and relaparotomy in two. One patient died in this group. Twenty-three of 29 patients had a pHi of 7·1 or less, of whom 15 had a pHi of 6·9 or less. Sixteen had an IAP of 20 mmHg or more, of whom ten also had a pHi below 6·90. Peak IAP values correlated with the simultaneously measured pHi (r = –0·39, P = 0·003).

Conclusion

Raised IAP is an important mechanism behind colonic hypoperfusion after rAAA repair. Monitoring IAP and timely intervention may improve outcome.

The Clinical Importance of Monitoring Intra Abdominal Pressure after Ruptured Abdominal Aortic Aneurysm Repair

Aim:

The aim of this paper was to review the literature on the clinical importance of monitoring intra-abdominal pressure (IAP) after ruptured abdominal aortic aneurysm (rAAA) repair.

Method:

The literature was searched for abdominal compartment syndrome (ACS) or intra-abdominal pressure and aortic aneurysm. Original articles were studied. Personal experiences were reported.

Results:

The consensus documents of the World society on the abdominal compartment syndrome ( wsacs.org ), with their definitions and guidelines, constitute an important step forward for the possibilities to study this clinical entity. Few papers were published describing the problem specifically in the patient population operated on for ruptured abdominal aortic aneurysm (rAAA). The incidence was approximately 5% when the patients were not monitored with IAP, and above 10% when IAP was monitored. The incidence seems to be similar irrespective if open or endovascular repair is performed, though comparative prospective studies were not published. Patients with intra-abdominal hypertension (IAH) or ACS have higher mortality and more complications. If IAH is recognized early conservative treatment may be effective to prevent development of ACS. After ACS has developed, surgical decompression is usually required. A proposed algorithm on how to act on different levels of IAH is presented.

Conclusions:

IAH/ACS is an important complication after operation on patients with rAAA. Monitoring IAP may be associated with improved outcomes.

Predictors for Outcome after Open and Endovascular Repair of Ruptured Abdominal Aortic Aneurysms

OBJECTIVES

The aims of the present study were to analyze patient- and management-related predictors for outcome after open (OR) and endovascular repair (EVAR) of ruptured abdominal aortic aneurysm (rAAA).

DESIGN

Retrospective study.

MATERIALS

The in-hospital registry of Malmö University Hospital identified 162 patients operated on due to rAAA between 2000 and 2004.

METHODS

Patient- and management-related predictors for outcome were analysed.

RESULTS

Preoperative CT in 39 out of 62 circulatory unstable patients was not associated with increased mortality (p=0.60). There was a significant increase in repairs performed by EVAR during the study period (p<0.001), and in 2004 EVAR exceeded the annual rate of OR. Patients in the EVAR group were older (p=0.025), whereas patients in the OR group more often suffered from unconsciousness after presentation (p=0.004). Age, unconsciousness after presentation and haemoglobin were significantly associated with in-hospital mortality when tested in a multivariate logistic regression model (p=0.002, p=0.003 and p<0.001, respectively). The in-hospital mortality for patients undergoing OR and EVAR was 45% (48/106) and 34% (19/56), respectively (p=0.16). Diagnosis of abdominal compartment syndrome (p=0.005) and intestinal infarction (p=0.002) was associated with poor survival.

CONCLUSIONS

Patient-related factors such as age, loss of consciousness and haemoglobin predicts outcome in a population where both emergency OR and EVAR for the treatment of rAAA is feasible.

Fatal colonic ischemia: A population-based study

OBJECTIVES

To estimate the incidence of fatal colonic ischaemia (CI) and the cause-specific mortality of CI, and to describe the localization and extension of colonic infarction and quantify the risk factors associated with CI.

MATERIAL AND METHODS

Between 1970 and 1982 the autopsy rate in Malmö, Sweden, was 87%, creating the possibilities for a population-based study. Out of 23,446 clinical autopsies, 997 cases were coded for intestinal ischaemia in a database. In addition, 7569 forensic autopsy protocols were analysed. In a case-control study nested in the clinical autopsy cohort, four CI-free controls, matched for gender, age at death and year of death, were identified for each fatal CI case in order to evaluate the risk factors.

RESULTS

The cause-specific mortality ratio was 1.7/1000 autopsies. The overall incidence of autopsy-verified fatal CI was 1.7/100,000 person years, increasing with age up to 23/100,000 person years in octogenarians. Fatal cardiac failure (odds ratio (OR) 5.2), fatal valvular disease (OR 4.3), previous stroke (OR 2.5) and recent surgery (OR 3.4) were risk factors for fatal CI. Narrowing/occlusion of the inferior mesenteric artery (IMA) at the aortic origin was present in 68% of the patients. The most common segments affected by transmural infarctions were the sigmoid (83%) and the descending (77%) colon.

CONCLUSIONS

Heart failure, atherosclerotic occlusion/stenoses of the IMA and recent surgery were the main risk factors causing colonic hypoperfusion and infarction. Segments of transmural infarctions were observed within the left colon in 94% of the patients. Awareness of the diagnosis and its associated cardiac comorbidities might help to improve survival.

Intraoperative colon mucosal oxygen saturation during aortic surgery

BACKGROUND

Colonic ischemia after aortic reconstruction is a devastating complication with high mortality rates. This study evaluates whether Colon Mucosal Oxygen Saturation (CMOS) correlates with colon ischemia during aortic surgery.

MATERIALS AND METHODS

Aortic reconstruction was performed in 25 patients, using a spectrophotometer probe that was inserted in each patient's rectum before the surgical procedure. Continuous CMOS, buccal mucosal oxygen saturation, systemic mean arterial pressure, heart rate, pulse oximetry, and pivotal intra-operative events were collected.

RESULTS

Endovascular aneurysm repair (EVAR) was performed in 20 and open repair in 5 patients with a mean age of 75 +/- 10 (+/-SE) years. CMOS reliably decreased in EVAR from a baseline of 56% +/- 8% to 26 +/- 17% (P < 0.0001) during infrarenal aortic balloon occlusion and femoral arterial sheath placement. CMOS similarly decreased during open repair from 56% +/- 9% to 15 +/- 19% (P < 0.0001) when the infrarenal aorta and iliac arteries were clamped. When aortic circulation was restored in both EVAR and open surgery, CMOS returned to baseline values 56.5 +/- 10% (P = 0.81). Mean recovery time in CMOS after an aortic intervention was 6.4 +/- 3.3 min. Simultaneous buccal mucosal oxygen saturation was stable (82% +/- 6%) during aortic manipulation but would fall significantly during active bleeding. There were no device related CMOS measurement complications.

CONCLUSIONS

Intra-operative CMOS is a sensitive measure of colon ischemia where intraoperative events correlated well with changes in mucosal oxygen saturation. Transient changes demonstrate no problem. However, persistently low CMOS suggests colon ischemia, thus providing an opportunity to revascularize the inferior mesenteric artery or hypogastric arteries to prevent colon infarction.

Intensive care of the patient following open abdominal aortic surgery

PURPOSE OF REVIEW

Abdominal aortic aneurysms still require open repair despite the advances that endovascular aneurysm repair has made in treating patients with significant operative risk. Older patients with significant comorbidities require open repair of their complex aneurysms when they fail to meet anatomic criteria for endovascular aneurysm repair. This review discusses the physiologic insult of abdominal aortic surgery. It aims to address which patients are the highest risk of postoperative morbidity, and advances in their intensive care unit management to reduce such morbidity.

RECENT FINDINGS

Advanced age, chronic health dysfunction, emergency surgery, and multiple organ failure are independent predictors of postoperative mortality. Myocardial ischemia is the largest contributor to patient morbidity, with any rise in postoperative cardiac troponin I predicting increased in-hospital myocardial infarction and mortality. Highest-risk patients benefit most from optimizing perioperative cardiac status with beta-blockade. Perioperative treatment with fenoldopam may improve renal outcome. Tracheostomy to aid in weaning is associated with increased mortality but may improve outcome in patients with preoperative chronic obstructive pulmonary disease.

SUMMARY

Demographic trends indicate that open aortic surgery will continue to be performed on older patients with complex aneurysms. Identifying patients at risk and optimizing their postoperative risk factors will improve outcomes.

A comparison among portal lactate, intramucosal sigmoid Ph, and deltaCO2 (PaCO2 - regional Pco2) as indices of complications in patients undergoing abdominal aortic aneurysm surgery

Our aim in this observational, prospective, noncontrolled study was to detect, in 29 patients who underwent abdominal aortic aneurysm (AAA) surgery, correlations between the incidence of postoperative organ failure and intraoperative changes in arterial and portal blood lactate; changes in intramucosal sigmoid pH (pHi); differences between sigmoid Pco(2) and arterial Pco(2) (DeltaCO(2)); and hemoglobin (Hb). Hb, arterial blood lactate concentrations, pHi, and DeltaCO(2) (air tonometry) were recorded at the start of anesthesia (T0), before aorta clamping (T1), 30 minutes after clamping (T2), and at the end of surgery (T3). Portal venous lactate concentrations were recorded at T1 and T2. Patients were stratified into two groups: group A patients had no postoperative organ failure, and group B patients had one or more organ failures. As compared with group A (n = 16), group B patients (n = 13) had a lower pHi value at T2 and T3 and a higher DeltaCO(2) at T3. A pHi value of <7.15 was a predictor of organ failure, with a sensitivity of 92.3%, a specificity of 68.8%, and positive and negative predictive values of 70.6% and 91.7%, respectively, whereas a DeltaCO(2) value of >28 mm Hg predicted later organ failure with a sensitivity of 92.3%, a specificity of 62.5%, and positive and negative predictive values of 66.6% and 90.9%, respectively. Portal venous lactate concentrations were larger in group B at T2 (P < 0.001), and an increase >or=5 g/dL predicted later postoperative organ failure with a sensitivity of 92.3%, a specificity of 100%, and positive and negative predictive values of 100% and 94.1%, respectively. The comparison of the receiving operator characteristic curves to test the discrimination of each variable and the logistic regression analysis revealed that the increase in portal lactate was the best predictor for the development of postoperative organ failure. Hb concentration was significantly smaller in group B at T0 (13.8 +/- 1.0 g/dL versus 12.2 +/- 2.2 g/dL) and T2 (10.9 +/- 1.2 g/dL versus 9.1 +/- 1.9 g/dL). In conclusion, both pHi and DeltaCO(2) are reasonably sensitive prognostic indices of organ failures after AAA surgery, but they are less specific and accurate than portal venous lactate.

Ischaemia-Reperfusion Injury and Regional Inflammatory Responses in Abdominal Aortic Aneurysm Repair

OBJECTIVES

The inflammatory response to abdominal aortic aneurysm repair is likely to result in response to an ischaemia-reperfusion injury (IRI) to the lower-limbs and gastrointestinal tract. This paper reviews the pathogenesis of the inflammatory response to abdominal aortic aneurysm repair, with specific reference to the levels of evidence in the current literature regarding the potential origin of the inflammatory response.

DESIGN

Review article.

METHODS

The current literature (1966 to August 2003) was reviewed specifically for all articles employing techniques of regional blood sampling from the venous drainage of the lower limbs or gastrointestinal tract during abdominal aortic aneurysm repair.

RESULTS

Ten relevant studies were identified. These demonstrated that regional blood sampling techniques could be easily performed, and provided useful information regarding the potential sites of origin of the inflammatory response.

CONCLUSIONS

Regional blood sampling techniques provide useful information regarding the potential sites of origin of the inflammatory response. Current evidence suggests that both the lower limbs and gastrointestinal tract are clearly important in their roles, however more work is now required to compare directly the roles and contributions of the lower limbs and gastrointestinal tract to the inflammatory response during abdominal aortic aneurysm repair.

Non-occlusive mesenteric ischaemia: a common disorder in gastroenterology and intensive care

Non-occlusive mesenteric ischaemia is characterized by gastrointestinal ischaemia with normal vessels. In gastroenterology it is recognized as rare disease occasionally causing acute bowel infarction or ischaemic colitis. From intensive care literature this disorder is recognized as an early phenomenon during circulatory stress. This early mucosal ischaemia then leads to increased permeability, bacterial translocation, and further mucosal hypoperfusion. The damage is produced mainly during reperfusion following ischaemia with fresh inflow of oxygen and outflow of waste products into the systemic circulation. The mechanisms underlying non-occlusive mesenteric ischaemia include macrovascular vasoconstriction, hypoperfusion of the tips of the villi and shunting. It is very common in critically ill and perioperative patients, but also occurs in pancreatitis, renal failure and sepsis. Treatment options include aggressive fluid resuscitation and careful choice of vasoactive drugs. Control of reperfusion damage and new endothelin-antagonists are potentially useful new treatment options.

Gastric hypercarbia and adverse outcome after cardiac surgery

OBJECTIVE

It has been postulated that splanchnic ischemia, as manifested by gastric hypercarbia, helps to trigger excessive systemic inflammation, which has been linked to the development of adverse postoperative outcome. This study examined whether gastric PCO(2) values are associated with adverse outcome in cardiac surgical patients.

DESIGN AND SETTING

Prospective cohort study in a tertiary-care hospital.

PATIENTS

43 patients undergoing elective cardiac surgery.

INTERVENTIONS

Simultaneous measurements of gastric PCO(2) (using automated air tonometry) and arterial PCO(2) were obtained at the beginning and end of surgery. The difference (gap) between regional PCO(2) and arterial PCO(2) (corrected for temperature) was calculated. Adverse outcome was defined as in-hospital death or prolonged (>10 days) postoperative hospitalization.

MEASUREMENTS AND RESULTS

Fourteen patients fulfilled the predefined definition for adverse outcome. Postoperative ICU stay and postoperative hospital length of stay were significantly longer in these patients. At the end of surgery gastric minus arterial PCO(2) gap was significantly larger in patients with adverse outcome. Global hemodynamic and perfusion related variables were not associated with adverse outcome (cardiac index, mean arterial pressure, mixed venous oxygen saturation, arterial lactate, arterial base excess).

CONCLUSIONS

Gastric minus arterial PCO(2) gap after surgery is larger in patients with adverse postoperative outcome, which supports the theory that gastrointestinal reduced perfusion is relevant to the pathogenesis of postoperative morbidity.

Influence of diagnostic criteria on the prevalence of abdominal aortic aneurysm

PURPOSE

We studied the prevalence of abdominal aortic aneurysm (AAA) in a population with high incidences of cardiovascular diseases and analyzed how the prevalence varies according to methodology and criteria.

METHODS

All men and women aged 65 to 75 years who lived in the Norsjö municipality in northern Sweden were invited to undergo an ultrasound scanning (US) examination. Those with an aortic diameter of 28 mm or more or with poor visibility on US were examined with computed tomography scanning (CT). Various recommended AAA definitions, two diagnostic methods (US and CT), and two diameters (maximum and anteroposterior) were analyzed.

RESULTS

Of 555 people invited to participate in the study, 504 accepted (248 men and 256 women; 91%). Eight subjects had undergone surgery for an AAA. Ninety-two subjects underwent CT. The mean maximum infrarenal aortic diameter was 24.6 mm (by means of US). Depending on diagnostic criteria, the AAA prevalence was 3.6% to 16.9% in men and 0.8% to 9.4% in women. Depending on which previous study was used as a comparison and the definition of AAA and diagnostic technique used, the prevalence in this study was 1.3 to 4.0 times higher for men and 2.0 to 5.8 times higher for women.

CONCLUSION

In a region in which residents have a high risk for cardiovascular disease, we found the highest prevalence of AAA ever reported within a population. The prevalence highly depends on methodology and diagnostic criteria, with a 10-fold variation. Detailed defined criteria are necessary to permit comparisons between studies: the number of individuals who have undergone surgery for AAA and whether they are included, the prevalence in 5- and 10-year age intervals, attendance rate, visibility, which diameter(s) is measured, and the prevalences with as many as possible of the four described definitions of AAA. The etiology of the high prevalence of AAA in this population needs to be investigated further.