P. Aadahl

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.

Gut luminal microdialysis of glycerol as a marker of intestinal ischemic injury and recovery

Objective:To evaluate microdialysis as a method to assess different degrees of intestinal damage and recovery during ischemia and reperfusion; to evaluate information obtained from microdialysis catheters in the peritoneum, the gut wall, and the gut lumen. Design:Randomized, controlled animal experiment. Setting:University laboratory animal center. Subjects:Twenty-seven domestic pigs. Interventions:The superior mesenteric artery was cross-clamped for 60 mins (n = 14) or 120 mins (n = 10) followed by 2 or 4 hrs of reperfusion. Three pigs served as controls. Measurements and Main Results:Intestinal mucosal integrity was assessed by morphometry, adenosine triphosphate in the gut wall, and permeability of 14C-polyethylene glycol. Lactate, glycerol, pyruvate, and glucose were measured by microdialysis. Changes in adenosine triphosphate, permeability, or lactate did not correlate to different extents of intestinal damage caused by 60 or 120 mins of ischemia. During the reperfusion period, pigs with 60 mins of intestinal ischemia showed a faster recovery of these variables than pigs with 120 mins of intestinal ischemia. Glycerol increased with increasing duration of the ischemic insult. After 60 mins of intestinal ischemia, glycerol in the gut lumen decreased toward baseline but remained high after 120 mins of intestinal ischemia. There was a good correlation between gut luminal glycerol and recovery of mucosal damage throughout the reperfusion period. In the peritoneal cavity, both glycerol and lactate decreased to baseline relatively shortly after onset of reperfusion independent of the duration of intestinal ischemia. Conclusions:Microdialysis of glycerol provides information about the extent and severity of intestinal damage after ischemia and about the ensuing recovery. The gut lumen is to be preferred as a site for placement of microdialysis catheters.

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.

A Validated Method for Rapid Analysis of Ethane in Breath and its Application in Kinetic Studies in Human Volunteers

Oxidative stress may initiate lipid peroxidation that generates ethane. Ethane, at low concentrations, is eliminated by pulmonary exhalation. Previous methods have not allowed frequent sampling, thus ethane kinetics has not been studied in man. A validated method over the range 3.8-100,000 ppb with a limit of quantitation of 3.8 ppb (CV 9.3%) based on cryofocusing technique of a 60 ml breath sample allowed frequent sampling. Due to a rapid analytical procedure batches of more than 100 samples may be analyzed. In human volunteers (24-55 years) uptake was studied for up to 23 min <formula>(<italic>n</italic>=9)</formula>, elimination was studied for 210 min <formula>(<italic>n</italic>=9).</formula> Ethane was inhaled (concentrations varied from 16 to 29 ppm (parts per million)) through a non-rebreathing system; sampling was performed with short intervals from the expiratory limb. Samples were also drawn from the inhalatory limb. Ninety-five percent of steady state (inspired) concentration was reached within 1.75 min. Five percent of the initially inhaled concentrations was found in exhaled air 1.5 min after termination of inhalation. A terminal mean half life of 31 min for ethane was also observed. The data indicate that frequent sampling will be necessary to capture relevant changes in breath ethane.

A closed-chest pulmonary artery occlusion/reperfusion model in the pig: detection of experimental pulmonary embolism with MR angiography and perfusion MR imaging.

RATIONALE AND OBJECTIVES To establish a pig model suitable for imitating pulmonary emboli to facilitate research in the diagnosis of pulmonary embolism. METHODS Thirteen animals were anesthetized, mechanically ventilated, and subjected to pulmonary artery catheterization initiated from the right external jugular vein. With the use of a Swan-Ganz catheter, repetitive occlusion/reperfusion maneuvers were done at different locations of the pulmonary arterial tree. Conventional pulmonary angiography, MR angiography, and perfusion MR imaging were performed. RESULTS The model remained hemodynamically stable throughout the 13 experiments, without any significant difference between the blood pressure measurements at the start and at the end of the right-heart and pulmonary artery catheterizations. In each of the nine animal experiments that investigated MR imaging, four of four using perfusion MR imaging (proximal and distal occlusions) and five of five using MR angiography (larger pulmonary artery occlusions), all repeated pulmonary artery occlusions were successfully performed (reproducibility of 100%). CONCLUSIONS The closed-chest pulmonary artery occlusion/reperfusion model in the pig allowed repetitive, controlled imitations of pulmonary emboli at different levels of the pulmonary artery in the same experiment. MR angiography and perfusion MR imaging were adequate to detect the pulmonary artery occlusions and the nonperfused lung regions, respectively. The model may be a helpful tool for future research in this field.

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.

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

A 21/2‐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.

Microdialysis of the spinal cord during thoracic aortic cross-clamping in a porcine model.

Objective: Utilising microdialysis to measure the changes of glucose, lactate, pyruvate and glutamate levels in the spinal cord after cross-clamping of the thoracic aorta in an established porcine model to monitor the degree of ischaemia. Design: Experimental study with a porcine model. Setting: University Hospital, Trondheim. Subjects: Six pigs. Main outcome measure: Lactate, pyruvate and glutamate concentrations in the microdialysis perfusate from the spinal cord. Results: A significant increase of the lactate-pyruvate ratio during the last 30 min of the 1 h clamping period, with a maximum increase of 169% from the basal value the last 10 min before declamping. No evident change in this ratio between the clamping and the reperfusion period. No significant change in glutamate levels during clamping or reperfusion period. Conclusion: Microdialysis reflects the ischaemic state of the spinal cord during cross-clamping of the thoracic aorta in pigs, and is well suited to study each phenomena. Spinal Cord (2000) 38, 153–157.

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

We describe a 58‐year‐old female with Crohns 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 (Ringers 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.

Cardiac output measurements during cross‐clamping of the descending thoracic aorta in pigs

Background: Cross‐clamping of the descending thoracic aorta (XC) induces an increase in cardiac output (CO). The intention of this study was to evaluate the high CO during XC by the use of clinically available methods (thermodilution and pulsed Doppler ultrasound) compared to transit‐time ultrasound flowmetry of the ascending aorta as the gold standard.