Pharmacokinetics of intraperitoneally instilled aminophylline, terbutaline and tobramycin in pigs.

INTRODUCTION: Venous catheters are sometimes difficult or even impossible to insert and may also be associated with serious complications. This study was carried out to investigate whether intraperitoneal administration of drugs may be an alternative to the intravenous route in patients with limited vascular access. MATERIALS AND METHODS: Three drugs commonly in use in clinical practise, aminophylline, terbutaline and tobramycin, were administered to pigs intravenously and intraperitoneally in small volumes. Serum concentrations were analysed over a period of 6 h and pharmacokinetic key variables for each drug were calculated. RESULTS: Aminophylline (theophylline), terbutaline and tobramycin were absorbed from the peritoneal space and into systemic circulation. For theophylline, the concentration/time profiles after intraperitoneal and after intravenous administration were almost identical, and the intraperitoneal bioavailability was calculated to 0.94. For terbutaline and tobramycin, the intraperitoneal absorption was delayed without any initial peak. Moreover, the intraperitoneal bioavailability was lower than for theophylline (0.71 and 0.65, respectively). CONCLUSION: The pharmacokinetic properties after intraperitoneal administration differed among the three drugs, but the results are encouraging and provide a basis for further investigation in humans.

Regional distribution of blood flow during proximal aortic cross-clamping: an experimental study using coloured microspheres.

OBJECTIVE: To investigate the effect of thoracic aortic cross-clamping on blood perfusion of the brain, spinal cord, heart, muscular tissue and visceral organs. MATERIAL AND METHODS: Nine pigs underwent 30 min cross-clamping of the descending thoracic aorta. Multiple coloured microspheres (15.0 microm +/- 0.1) were infused into the left ventricle before and during aortic cross-clamping (XC) and after declamping (DC). Tissue samples were analysed by spectrophotometry. RESULTS: Blood perfusion of the middle and lower segments of the spinal cord was significantly reduced during aortic XC. Perfusion of the brain was not significantly altered by aortic XC, while perfusion of myocardium increased 3-fold. During XC, perfusion of the deltoid muscle and diaphragm increased 5-fold and 13-fold, respectively, while a decrease was found in the gluteus muscle. Renal blood flow was significantly reduced during XC. Finally, XC induced a significant decrease of perfusion in the bowel, spleen, liver and pancreas. CONCLUSION: During XC of the thoracic aorta, the perfusion of the muscular tissue was significantly increased proximal to the level of XC. The circulation of the brain was unchanged, probably because of autoregulatory mechanisms. Blood perfusion of the myocardium increased 3-fold during XC.

Side-branched AAA stent graft insertion using navigation technology: a phantom study.

OBJECTIVE: To evaluate the feasibility of a side-branched stent graft inserted in an artificial abdominal aortic aneurysm (AAA), using navigation technology, and to compare procedure duration and dose of radiation with control trials. METHODS: A custom-made stent graft was inserted into an artificial AAA using navigation technology in combination with fluoroscopy. The navigation technology was based on three-dimensional visualization of computed tomography data and electromagnetic tracking of microposition sensors. The stent graft had integrated position sensors in side branch and introducer and was guided into proper position with the aid of three-dimensional images. Control trials were performed with fluoroscopy alone. RESULTS: It was feasible to insert a side-branched stent graft using three-dimensional navigation technology. The navigation-guided trials had a significantly lower X-ray load (p < 0.001), but showed no difference in the duration of the procedures (p = 0.34) as compared with controls. CONCLUSIONS: Inserting a side-branched stent graft in an artificial AAA using navigation technology is feasible. Side-branched stent grafts and navigation systems may become useful in the endovascular treatment of complicated aortic aneurysms.

Overtriage in trauma - what are the causes?

BACKGROUND: Different criteria are employed to activate trauma teams. Because of a growing concern about overtriage, the objective of this study was to investigate the performance of our trauma team's activation protocol. METHODS: Injured patients with trauma team activation (TTA), admission to an intensive care unit or surgical intermediate care unit with a trauma diagnosis, or trauma-related death in the emergency department were investigated retrospectively from 1 January 2004 to 31 December 2005. Different TTA criteria were analysed with respect to sensitivity, positive predictive value (PPV) and overtriage (1 - PPV). RESULTS: Eight hundred and nine patients were included, 185 (23%) of whom had an Injury Severity Score (ISS) of more than 15. The performance of our protocol showed a sensitivity of 87%, PPV of 22% and overtriage of 78%. The mechanism of injury as a TTA criterion had a sensitivity of 14%, PPV of 7% and overtriage of 93%. Physiological/anatomical criteria and interfacility transfer showed higher PPV and less overtriage. Undertriage (no TTA despite ISS > 15) was identified in 23 patients (13%), 18 of whom were hospital transfers. CONCLUSION: A TTA protocol based on physiological, anatomical and interfacility transfer criteria seems to yield a higher precision than, in particular, that based on mechanism of injury criteria. Because of substantial overtriage in our hospital, the TTA protocol needs to be re-evaluated.

Lactate and glycerol released to the intestinal lumen reflect mucosal injury and permeability changes caused by strangulation obstruction.

BACKGROUND: The present study evaluates whether microdialysis of glycerol and lactate reflects mucosal injury and permeability changes after strangulation obstruction of the pig small intestine. METHODS: Strangulation obstruction was induced by tightening a rubber band around a small bowel loop until its venous pressure increased to a level just below diastolic aortic pressure (partial strangulation), or further until cessation of flow in the main feeding artery (total strangulation). Mucosal injury and permeability of marker molecules from blood to lumen and vice versa was compared to release of glycerol and lactate to the intestinal lumen. RESULTS: Mucosal injury, hyperpermeability, and release of glycerol were more pronounced after total than after partial strangulation. In animals with partial strangulation there was a complete restitution of the surface epithelium, and luminal glycerol and lumen-to-blood permeability of polyethylene glycol 4000 remained low. Such animals showed a sustained elevation of lactate and blood-to-lumen permeability of fluorescein isothiocyanate dextran after 2 h of partial strangulation, but a decline to baseline levels of these parameters in animals with 1 h partial strangulation. CONCLUSION: Microdialysis of lactate and glycerol in the intestinal lumen may be used to assess structural and functional changes of the intestinal mucosa after strangulation obstruction.

Rectal lactate levels in endoluminal microdialysate during routine coronary surgery.

The aim of this prospective study was to determine the feasibility of intestinal endoluminal microdialysis as a new method for clinical monitoring of the adequacy of splanchnic perfusion in the large bowel. A microdialysis catheter for continuous lactate, glycerol, glucose and pyruvate measurements attached to a tonometric catheter was placed into the lumen of the recto-sigmoid junction prior to surgery in 13 patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB). Lactate was also measured in blood and muscle. CPB was associated with a 10-fold increase in luminal lactate from 0.16 (0.01) to 1.67 (0.38) mmol x l(-1) (p < 0.001). Muscular lactate increased from baseline levels 1.20 (0.21) to 1.77 (0.36) mmol x l(-1) during CPB (p = 0.01), but the muscular lactate-pyruvate ratio remained unchanged. Arterial lactate increased only slightly from 0.9 (0.05) to 1.1 (0.06) mmol x l(-1) (p = 0.027) during CPB. Increased lactate concentrations in the large bowel during CPB are suggestive of local lactate production consistent with impaired oxygen delivery. Intestinal endoluminal microdialysis is a potential clinically applicable method for monitoring intestinal metabolism. Combined with tonometry, microdialysis provides the opportunity to monitor both circulation and metabolism in the rectal mucosa.

Hemodynamic and tissue blood flow responses to long-term pneumoperitoneum and hypercapnia in the pig.

BACKGROUND: Increased peritoneal blood flow may influence the ability of cancer cells to adhere to and survive on the peritoneal surface during and after laparoscopic cancer surgery. Carbon dioxide (CO2) pneumoperitoneum is associated with a marked blood flow increase in the peritoneum. However, it is not clear whether the vasodilatory effect in the peritoneum is related to a local or systemic effect of CO2. METHODS: In this study, 21 pigs were exposed to pneumoperitoneum produced with either CO2 (n = 7) or helium (He) (n = 7) insufflation at 10 mmHg for 4 h, or to two consecutive levels of hypercapnia (7 and 11 kPa) (n = 7) produced by the addition of CO2 to the inhalational gas mixture. Tissue blood flow measurements were performed using the colored microsphere technique. RESULTS: Blood flow in peritoneal tissue increased during CO2, but not He, pneumoperitoneum, whereas it did not change at any level of hypercapnia alone. There was no change in blood flow in most organs at the partial pressure of CO2 (PaCO2) level of 7 kPa. However, at a PaCO2 of 11 kPa, blood flow was increased in the central nervous system, myocardium, and some gastrointestinal organs. The blood flow decreased markedly in all striated muscular tissues during both levels of hypercapnia. CONCLUSION: The effect of CO2 on peritoneal blood flow during laparoscopic surgery is a local effect, and not attributable to central hemodynamic effects of CO2 pneumoperitoneum or high systemic levels of CO2.

Intraperitoneal fluid therapy: an alternative to intravenous treatment in a patient with limited vascular access.

We describe a 58-year-old female with Crohn's disease and short bowel syndrome after repeated intestinal resections, with only 90 cm of small intestine left. She had been dependent on vascular access for total parenteral nutrition for 16 years. Due to intravascular complications after numerous long-term central venous catheters, her vascular accessibility became limited. During the course of a year she was fed enterally through a gastrostomy, but required supplementary fluid therapy through peripheral venous route. Because of extremely limited venous access, we decided to implant an intraperitoneal catheter for administration of crystalloid fluid. The first intraperitoneal catheter had to be removed because of a postoperative infection, but after antibiotic treatment, a second intraperitoneal catheter was implanted without complications, through which the patient is now fully provided with crystalloid fluid (Ringer's acetate). Abdominal ultrasound examination shows good absorption of the fluid, and for the first time in 16 years the patient does not need intravascular access. We suggest that intraperitoneal administration of fluid may be an alternative for patients with limited vascular access.

Spinal fluid dynamics during thoracic- and thoracoabdominal aortic surgery.

AIM: The intention was to investigate cerebrospinal fluid pressure (CSFP) and volume of cerebrospinal fluid (CSF) drained during and after thoracic- and thoracoabdominal aneurysm repair. The findings were related to the occurrence of postoperative neurologic deficits. METHODS: Twenty-nine patients (12 with thoracic and 17 with thoracoabdominal aortic aneurysm) were operated without shunting or extracorporeal circulation. For monitoring of CSFP an intrathecal catheter was placed in all patients. The volume of CSF withdrawn intraoperatively, on the day of operation as well as on the 1st and 2nd postoperative day was recorded. RESULTS: Twenty-six patients had no postoperative neurologic sequelae. One patient had postoperative paraplegia while 2 had paraparesis. The three patients with neurologic sequelae had higher CSFP intraoperatively than those without neurologic symptoms (P=0.04). Median CSFP during aortic cross-clamping was 19 mmHg and 10 mmHg and the median volumes of CSF drained on the day of operation 210 and 85 mL in the two groups, respectively. There was a significant positive correlation between CSFP and central venous pressure. CONCLUSIONS: A higher intraoperative CSFP was observed in patients with neurologic sequelae following thoracic- and thoracoabdominal aneurysm repair. Further, there was a tendency of higher volumes of CSF drained in this group of patients. Although, the series is too small to allow firm conclusions, it supports the view that CSFP monitoring and drainage is beneficial during thoracic- and thoracoabdominal aneurysm repair.

Recovery following treatment of descending thoracic aortic disease. A comparison between endovascular repair and open surgery.

AIM: The aim of this study was to compare the postoperative course in patients treated by endovascular repair (endo) with patients treated by open surgery (open) for descending thoracic aortic disease. METHODS: Twenty-five patients treated with stent grafting for aneurysmal disease or type B dissection were compared with 35 historical controls treated by open surgery. Stay in the intensive care unit, need for artificial ventilation and to where the patient had been discharged, were noted. Pain medication, use of nasogastric tube, time until total oral nutrition, mobilization and the patients' mental condition in the postoperative period, were studied in the patients charts and the nursing reports. RESULTS: Time on the intensive care unit or intermediate care unit was median 45 h in the endo group compared with 192 h in the open group. Eighty percent of the patients in the endo group were discharged directly to their homes in contrast to 23% after open surgery. In the endo group 67% of the patients started oral nutrition on the 1st postoperative day compared to 10% in the open group. There was a significantly faster mobilization in the endo group. CONCLUSIONS: There was a significantly shorter recovery after stent grafting for descending thoracic aortic disease compared to patients operated with open surgical technique.

Changes in hemodynamics and acid-base balance during cross-clamping of the descending thoracic aorta. A study in patients operated on for thoracic and thoracoabdominal aortic aneurysm.

AIM OF THE STUDY: In the clinical situation there is discrepancy between various investigations regarding the cardiac response of thoracic aortic cross-clamping. The aim was therefore to investigate the hemodynamic response and blood gases during proximal aortic cross-clamping (XC) in patients operated for descending thoracic and thoracoabdominal aortic aneurysm without circulatory support. PATIENTS AND METHODS: Altogether 51 patients operated on for thoracoabdominal (n=31) or descending thoracic aortic aneurysm (n=20) were included in the investigation. All patients were operated with aortic XC, but no circulatory support was applied. Hemodynamic variables and blood gases were recorded before and during XC. RESULTS: A significant increase in cardiac output during XC from 4.7 to 6.0 liters/min was observed (p<0.01). There was a similar percentual increase in heart rate and also the proximal systolic blood pressure increased. A metabolic acidosis occurred during XC. CONCLUSION: Cardiac output was significantly increased during XC in patients operated on for thoracoabdominal or descending thoracic aneurysm using direct aortic XC without circulatory support. Simultaneously, the heart rate was increased and there was a hyperdynamic circulatory state proximal to the aortic clamp. Redistribution of the blood volume in addition to catecholamine release may be responsible for the observed changes. These observations may influence the selection of operative strategy for some of these patients.

Emergency non-ruptured abdominal aortic aneurysm.

OBJECTIVES: To investigate symptoms and early mortality (<30 days) following open surgery for emergency, symptomatic non-ruptured abdominal aortic aneurysm (AAA). DESIGN: Retrospective cohort study. PATIENTS AND METHODS: During the period 1983-1994, 129 patients had an emergency admission, followed by surgery, for symptomatic non-ruptured AAA. Sixty-one received surgery within 24 h of admission and 68 received surgery more than 24 h after admission (median 135 h, inter-quartile range: 51-239 h). During the same period 239 patients had elective surgery for non-ruptured AAA. Early mortality (<30 days), symptoms and co-morbidities were recorded. Data were retrieved from the patient records. RESULTS: Mortality (30 days) was 18% in the 61 patients having surgery within 24 h of emergency admission for non-ruptured AAA. Mortality following either delayed surgery (semi-elective) after emergency admission or elective surgery was 4.2% (p=0.0002). Four out of 11 patients who died within 30 days following an acute operation had previously been declared unfit for elective surgery. One additional emergency patient had been found unfit for open surgery, but survived a delayed operation. CONCLUSION: The high mortality rate of patients with non-ruptured, symptomatic AAA undergoing surgery within 24 h of admission appears to be influenced by several factors, including co-morbidities and the acute operation. We propose that the 30-day mortality for non-ruptured AAA should be reported in two categories: mortality rate for elective surgery and mortality for surgery performed within 24 h of emergency admission. The term 'emergency non-ruptured' is a suitable term for the latter group.

A strategy for treatment of type III and IV thoracoabdominal aortic aneurysm.

The aim of this study was to describe the results of resection and graft replacement for type III and IV thoracoabdominal aortic aneurysm repair. In this retrospective study, 27 patients underwent resection and graft replacement for type III (10) or type IV (17) thoracoabdominal aortic aneurysms. Nine patients had rupture, 12 were symptomatic, and 6 were operated on electively. The "clamp-and-sew" technique was applied in six cases. In 12 patients with type IV aneurysm the proximal part of the vascular graft was beveled, including the orifices of the celiac, superior mesenteric, and one or both renal arteries in the proximal anastomosis. Finally, eight patients underwent surgical application of a shunt for perfusion of the celiac and superior mesenteric arteries. One patient was treated with a combination of open and endovascular surgery. There were four early deaths (14.8%), all following operations for rupture, which represents a 45% mortality rate in this subgroup of patients. Two patients with type III aneurysm had postoperative paraparesis. One was symptomatic whereas the other was operated on electively. Excluding the patients with rupture, the accumulated 5-year survival rate was 65%. These results indicate that direct cross-clamping of the aorta gives limited time for performing the necessary anastomoses without inducing mesenteric ischemia. Inclusion of the orifices of the visceral arteries in the upper anastomosis is a feasible method during surgery for type IV aneurysms. Finally, shunting of the celiac and the superior mesenteric arteries seems to be useful, especially during surgery for type III aneurysms.

Shunting of the coeliac and superior mesenteric arteries during thoracoabdominal aneurysm repair.

OBJECTIVES: To describe our experience with shunting of the coeliac and superior mesenteric arteries during thoracoabdominal aneurysm repair. DESIGN: Retrospective study. MATERIAL: Eight patients undergoing resection and graft replacement of Crawford type III (5) and type IV (3) thoracoabdominal aortic aneurysms were included in this series. One patient had rupture, four were symptomatic and three were operated on electively. METHODS: A vascular graft with a sidearm was applied for the reconstructions. A T-shunt was connected to the sidearm. Following completion of the proximal anastomosis the shunt was inserted into the coeliac and superior mesenteric arteries. The anastomoses to these arteries and the renal arteries were then completed. Finally the distal anastomosis was performed. RESULTS: There was no early mortality (30 days). One patient had postoperative paraparesis, but recovered quite well. Reoperation became necessary due to sigmoid necrosis in one patient and due to haemorrhage in another. During the follow-up period four patients died but the other patients are alive between 3 and 8 years after surgery. CONCLUSION: The application of shunting of the superior mesenteric and coeliac arteries during thoracoabdominal aortic surgery is feasible and the results have been acceptable. Further investigation of the optimal blood flow needed to avoid intestinal ischaemia in a larger series of patients is desirable.

Ultrasound-guided central venous cannulation in infants and children.

BACKGROUND: Percutaneous central venous cannulation in infants and children is a challenging procedure. Traditionally, an external landmark technique has been used to identify puncture site. An ultrasound-guided technique is now available and we wanted to evaluate this method in children and infants, looking specifically at the ease of use, success rate and complications. METHODS: Forty-two consecutive infants and children (median 16.5 [0-177] months and 10 [3-45] kg) scheduled for central venous catheter placement were registered. An ultrasound scanner made for guiding puncture of vessels was used. After locating the puncture site, a sterile procedure was performed using an accompanying kit to aid puncture of the vessel. RESULTS: Cannulation was successful in all patients and we had no complications during insertion of the catheters. The right internal jugular vein was preferred in most patients, and in 95% of the patients the vein was punctured at the first attempt. The median time from start of puncture to aspiration of blood was 12 (3-180) seconds. CONCLUSION: The ultrasound-guided technique for placement of central venous catheters was easy to apply in infants and children. It is our impression that it increased the precision and safety of the procedure in this group of patients.

Spinal cord metabolism during thoracic aortic cross-clamping in pigs with special reference to the effect of allopurinol.

OBJECTIVE: investigate the metabolic response of the spinal cord and the effect of allopurinol following cross clamping of the descending thoracic aorta in a porcine model. DESIGN: experimental animal study. MATERIALS: twelve domestic swine. Six pigs were pre-treated with allopurinol, while six pigs served as controls. METHODS: measurement of extracellular concentrations of glucose, pyruvate, lactate, glycerol and glutamate using microdialysis in the lumbar spinal cord. Measurement of lumbar spinal blood flow using laser Doppler technique. RESULTS: for all animals there was a significant decrease in concentrations of glucose and pyruvate together with a significant increase in the lactate-pyruvate ratio during aortic cross clamping. There was also a significant increase in glycerol concentrations 60 min after cross clamping, and a significant decrease in glutamate concentrations after 50 min. No differences in concentrations of glucose, pyruvate, lactate and glutamate or the glutamate-pyruvate ratio were observed between animals used as controls and those treated with allopurinol. The laser Doppler flux decreased to 40% of pre cross-clamp level, returning to normal values at declamping. CONCLUSION: the changes in energy-related metabolites reflect a considerable ischaemia in the spinal cord tissue but there was no convincing effect of allopurinol on the lumbar spinal cord metabolism during thoracic aortic cross clamping in this model.

Endovascular treatment of type B aortic dissections.

The purpose is to describe our experience with endovascular treatment of type B aortic dissections. Five patients were treated for complications following type B dissections like, false channel aneurysm formation, rupture and arterial obstruction. They were treated in general anaesthesia using a 'homemade' endoprosthesis or a commercially available endoprosthesis (Excluder) deployed during fluoroscopy. The patients have been followed at regular intervals with a median observation time of 18 months (range 12--36). One patient needed a secondary intervention due to dislodgement of the proximal stentgraft with haemorrhage into both the false and the true lumen. Otherwise there have been no early or late mortality or major complications in this series. Even if our experience with endovascular treatment of type B dissections is rather limited, the results so far are promising. Open surgery in many of these cases is complicated with high morbidity and mortality rate and the endovascular technique offers great advantages. A longer follow-up period is necessary to define the place of endovascular treatment.

Life-threatening upper airway obstruction in a child caused by retropharyngeal emphysema.

A 2 1/2-year-old boy with acute obstructive lung disease from adenovirus infection developed cough-induced paroxysms of intense dyspnoea leading to respiratory failure. Chest x-ray and fluoroscopy demonstrated retropharyngeal air occluding the airway. The clinical management of this and similar air-leak problems is discussed.

The inflammatory response following treatment of abdominal aortic aneurysms: a comparison between open surgery and endovascular repair.

OBJECTIVES: to compare the inflammatory response following endovascular and conventional AAA repair. DESIGN: prospective study. PATIENTS AND METHODS: ten patients were selected for open surgery (OPEN) and ten for endovascular (ENDO) AAA repair. Leukocytes, platelets, myeloperoxidase, lactoferrin, beta-thromboglobulin, C-reactive protein (CRP), interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and complement activation products were measured before, during and after surgery. RESULTS: in the OPEN group the median hospital stay was longer (6 vs. 12 days, p=0.001) and more patients required transfusion (p=0.02). IL-6 and CRP increased postoperatively, most in OPEN (p<0.01). Platelet counts decreased after the first angiography in ENDO (p<0.01) and before aortic cross-clamping in OPEN (p<0.05). The decrease was larger in OPEN (p=0.02). Leukocyte counts decreased after the first angiography in ENDO, and thereafter increased (p=0.001). An equivalent increase was observed in OPEN after declamping (p=0.001). Leukocyte and platelet degranulation products increased after the first angiography in ENDO and after declamping in OPEN. Changes in complement activation products were small. TNF-alpha did not change significantly. CONCLUSION: endovascular AAA repair caused significant leukocyte and platelet activation. Based on the timing of activation this could be caused by radiographic contrast media.