Major Abdominal Vascular Surgery Research Articles

Perioperative humoral stress response to laparoscopic versus open aortobifemoral bypass surgery

Minimally invasive surgery seems to reduce hormonal stress response to surgery, but has not previously been examined in major abdominal vascular surgery. Aortic cross-clamping time and operation time is known to be longer in the totally laparoscopic aortobifemoral bypass (LABF) as compared to open aortobifemoral bypass (OABF). The main objective of our study was to measure the hormonal stress response during surgery and aortic cross-clamping in patients undergoing a totally laparoscopic versus an open aortobifemoral bypass. This was a sub-study of a larger randomized controlled multicentre trial. Thirty consecutive patients with severe aortoiliac occlusive disease were randomized to either a laparoscopic (LABF) or an open (OABF) procedure. The surgical stress response was measured by perioperative monitoring of adrenocorticotropic hormone (ACTH), aldosterone, metanephrine and cortisol at eight different time-points. During surgery. there was an increase in all humoral stress markers in both groups. The analysis of covariance showed increased levels of cortisol and ACTH in open group at 24 h time-point as compared to the baseline and this difference was statistically significant between the two groups, which indicate an earlier return to baseline levels in the laparoscopic group. Results from the General Estimated Equations (GEE) model indicate that LABF generates a lower level of metanephrine and higher level of aldosterone as compared to OABF. In conclusion, although they have higher levels of ACTH, aldosterone and cortisol during surgery, the patients operated with a laparoscopic aortobifemoral bypass achieve earlier hormonal homeostasis after surgery compared to open aortobifemoral bypass.

Arterio-Ureteral Fistula: 11 New Cases of a Wolf in Sheep’s Clothing

We provide insight into the presentation, diagnostics, treatment, and accompanying clinical difficulties and complications of an arterio-ureteral fistula and add 11 patients with arterio-ureteral fistula to the 90 described in the literature. A retrospective search was done for confirmed cases of arterio-ureteral fistula that were treated at 3 medical centers. A total of 11 cases of arterio-ureteral fistula were reviewed from 1980 to 2006. A history of major abdominal surgery had an essential role in 10 of the 11 cases, especially vascular intervention in 8. All patients presented with varying manifestations of hematuria. Ureteral contrast studies and nonprovocative angiography provided the most valuable diagnostic information with all 5 and 3 of 5 showing positive results, respectively. In 4 of 11 patients (36%) the diagnosis of arterio-ureteral fistula was only made during laparotomy. Ten patients were treated with a classic open surgical approach (vascular and urological) and in 1 endovascular stents were inserted. Two of 11 patients (18%) needed acute surgical intervention because of hemodynamic instability. The in hospital mortality rate was 9%. At a mean followup of 17 months 3 other patients (27%) had died of causes unrelated to the arterio-ureteral fistula. The diagnosis of arterio-ureteral fistula should be considered in patients with persistent hematuria who have a history of major abdominal vascular surgery even when diagnostic test results are negative for a fistula, because in 36% of our patients the diagnosis could only be made at operation. The in hospital morbidity and mortality rates are considerable and, therefore, a timely diagnosis and elective multidisciplinary treatment are preferred.

Bilateral paravertebral analgesia for major abdominal vascular surgery: a preliminary report

Paravertebral analgesia is highly effective in blocking unilateral afferent input from the trunk, but its bilateral use does not appear to have been described. Eight patients undergoing major abdominal vascular surgery had pre-operative bilateral paravertebral catheters inserted. A dose of 25 ml of bupivacaine 0.5% divided between the two catheters provided the basis of an effective intra-operative analgesic regimen which was continued postoperatively by infusion of bupivacaine for 4 days. Diclofenac and morphine completed a balanced analgesic regimen which was started pre-operatively and continued for 5 and 3 days respectively. Cardiovascular stability was notable throughout surgery, even with aortic clamping and all patients were extubated at the end of surgery. Good quality analgesia was obtained as assessed by low postoperative pain scores at rest and on movement. Three patients were not admitted to the intensive care unit, where mean stays for the group was 10 h (range 0-24 h) and mean hospital stay was 10 days (range 7-14). There were no additional demands made on the nursing staff and no postoperative pain-related complications occurred. We conclude that bilateral paravertebral analgesia, as part of a balanced analgesic technique, is an alternative method of providing effective afferent blockage for major abdominal surgery.

Anaesthesia for abdominal vascular surgery in patients with coronary artery disease (CAD), part I: isoflurane produces dose-dependent coronary vasodilation

The effects of anaesthesia for major abdominal vascular surgery on coronary flow regulation and mechanisms of myocardial ischaemia were studied in 56 patients with CAD, using a randomized, partly double-blinded protocol. After induction with fentanyl (3 micrograms.kg-1) and thiopentone (2-4 mg.kg-1) and tracheal intubation, principal anaesthetics were nitrous oxide/oxygen (60/40) with isoflurane (n = 20), halothane (n = 19) or fentanyl (15-20 micrograms.kg-1) (n = 17). Conventional invasive techniques and coronary venous retrograde thermodilution were used to assess systemic and coronary haemodynamics. Coronary vascular resistance was estimated from myocardial oxygen extraction. Myocardial ischaemia was diagnosed by 12-lead ECG and/or anterior wall motion abnormalities by cardiokymography and/or myocardial lactate production. When adjustment of anaesthetic dose was insufficient for haemodynamic control, i.v. phenylephrine and nitroglycerine were administered to treat hypotension and hypertension or cardiac failure respectively. Measurements were performed at four specific intervals; awake, before surgery and 10 and 30 min after abdominal incision. Comparable changes of systemic haemodynamics and myocardial oxygen consumption were observed in the three groups. Coronary vasodilation was evidenced in isoflurane patients only and was linearly dose-dependent (P < 0.001). Partial Least Squares Projections to Latent Structures modelling with cross validation confirmed this dose-dependency and ruled out a clinically measurable influence by intervention drugs or simultaneous systemic haemodynamic abnormalities. The incidence of myocardial ischaemia during anaesthesia and surgery was comparable in the three groups (35, 37 and 24%, respectively) and there was an association with systemic haemodynamic aberrations in 19 of the 27 ischaemic episodes. In contrast to ischaemic halothane and fentanyl patients, isoflurane patients with ischaemia had significantly lower myocardial oxygen extraction (P = 0.008 and P = 0.001, respectively), indicating that the oxygen extraction reserve was not utilized in a normal way during ischaemia.

Preoperative and Intraoperative Factors Associated With Prolonged Mechanical Ventilation: A Study in Patients Following Major Abdominal Vascular Surgery

A study of 51 patients undergoing elective major abdominal surgery was carried out to determine the incidence of postoperative respiratory failure requiring mechanical ventilation for more than 24 h and which preoperative and intraoperative factors are associated with this respiratory complication. Mechanical ventilation for more than 24 h was required in 12 of the 51 patients. These 12 patients had a significantly longer stay in the intensive care unit and in the hospital than the patients who were successfully extubated in the postoperative period. Also, there was a trend for a higher mortality in the ventilated group compared to the group of patients who did not require postoperative ventilation. Preoperative abnormalities in FEV1 did not identify which patients were destined to require postoperative ventilation. Significant differences for the ventilated versus the nonventilated patients included a longer history of cigarette smoking, a lower preoperative PaO2, and a large intraoperative blood loss.

Deep vein thrombosis prophylaxis: a survey of current practice in Australia and New Zealand.

A survey of current practice for deep vein thrombosis (DVT) prophylaxis was undertaken in Australia and New Zealand. The most common indications for prophylaxis were a history of thrombo-embolism, the type and length of surgery and obesity. Prophylaxis was used in 65% of patients having hip surgery and in 39% undergoing knee surgery. In general surgery the corresponding rate was around 67% for colorectal surgery, hepatobiliary, upper gastrointestinal and major abdominal vascular surgery. Apart from open-heart cardiothoracic surgery (66%), use in other specialties was less than 50%. Physical methods (anti-embolism stockings, calf stimulation and calf compression devices) were most commonly used for prophylaxis (46%) with heparin being used by 40%. The main side effect reported with heparin was bleeding (18%). The estimated incidence of DVT and pulmonary embolus (PE) was 2.8 and 0.4% for general surgery, 2.7 and 0.7% for orthopaedic surgery and 6.6 and 1.3% for hip surgery. Intravenous heparin followed by oral anticoagulants was the most commonly used treatment for established DVT and nearly all respondents used intravenous heparin and oral anticoagulants for treatment of PE. Venography was the favoured objective test for diagnosing DVT. The principal reason for considering a change in prophylactic policy was the potential availability of an agent with increased efficacy and a reduced incidence of haemorrhagic complications.

Late postoperative nocturnal dips in oxygen saturation in patients undergoing major abdominal vascular surgery. Predictive value of pre-operative overnight pulse oximetry.

Twenty-four patients (23 male) who presented for aortic reconstructive surgery were studied with pulse oximetry on a pre-operative night and during the first five postoperative nights. Patients with five or more dips in oxygen saturation of greater than 4% (with a prompt recovery back toward baseline of 3% or more) per hour of monitoring were classified as having a significant abnormality of respiration. Pre-operatively, four of 24 patients (17%) demonstrated such an abnormality. Postoperatively, 12 patients (50%) met these criteria on at least one of the first five postoperative nights and six of these had two or more nights with severe episodic hypoxaemia. Frequent severe episodic dips in arterial oxygen saturation (to less than 85% saturation) occurred in the late postoperative period at a time when oxygen therapy would usually have been discontinued. Pre-operative overnight pulse oximetry studies fail to predict the development of abnormal respiratory patterns in the postoperative period in the majority of patients.

POSTOPERATIVE HYPOXAEMIA AFTER MAJOR ABDOMINAL VASCULAR SURGERY

We have studied the severity and duration of nocturnal hypoxaemia before operation and for the first five nights after operation after elective major abdominal vascular surgery. Oxygen supplementation was almost 100% effective in keeping oxygen saturation greater than 90% during the early postoperative period; however, 50% of patients spent prolonged periods with an SpO2 less than 85% during at least one night after operation. The risk of severe hypoxaemia persists well beyond the current prescription of supplementary oxygen in these high risk patients. A significant association exists between the mean preoperative overnight saturation value and the nocturnal saturation observed subsequently in the later postoperative period.

Ascorbic acid prevents cimetidine-induced decrease of serum hydrocortisone concentrations

A blind, parallel, prospective, clinical study was conducted to investigate the effect of ascorbic acid on human serum hydrocortisone concentrations which were decreased by the administration of cimetidine. The study population included 16 male adults scheduled for major abdominal vascular surgery. The study was conducted in surgical patients under anaesthesia, in which steroidogenesis was inhibited by cimetidine. The results showed a reduction in serum hydrocortisone concentrations in patients receiving a placebo. In patients receiving ascorbic acid, there was a significant increase in serum hydrocortisone concentration. This reflects the normal serum hydrocortisone profile for this operation and anaesthetic technique. Cimetidine can bind to cytochrome P-450 covering the active haem group, the cytochrome proves to be of vital importance for hydroxylation reactions, involved in human steroidogenesis. Serum hydrocortisone concentrations will decrease when cytochrome P-450 becomes blocked. Intravenous administration of ascorbic acid was supposed to cause relief for this decrease. The reasons are undetermined yet. This investigation proved that ascorbic acid can prevent cimetidine-induced decrease of human serum hydrocortisone concentrations.

Inhibition of Steroidogenesis by Cimetidine in Man: A Double-Blind, Prospective Study

This article concerns a double-blind, prospective, study. The experiments were performed in 10 adult male volunteers, scheduled for major abdominal vascular surgery. The effect of cimetidine on the steroidogenesis was compared with the effect of ranitidine. There proved to be a 40% reduction in the serum Cortisol concentration in the group of patients treated with cimetidine. In the ranitidine group it was not possible to demonstrate a significant decrease of the serum Cortisol concentration. Cimetidine is a drug containing a free imidazole ring. Imidazoles can bind to the cytochrome P-450. The lack of clinical phenomena caused by a blockade of the cytochrome P-450 is not exactly understood. For that reason, this study was extended. At the end of the first study, ascorbic acid was administered, as in case of etomidate. The reversibility of the blockade could be demonstrated also in the case of cimetidine. The serum Cortisol concentrations increased only in the case of cimetidine. This was not seen in the ...