Clinical experience with microdialysis catheters in pediatric liver transplants.

Ischemic vascular complications and rejection occur more frequently with pediatric liver transplants versus adult liver transplants. Using intrahepatic microdialysis catheters, we measured lactate, pyruvate, glucose, and glycerol values at the bedside for a median of 10 days in 20 pediatric liver grafts. Ischemia (n = 6), which was defined as a lactate level > 3.0 mM and a lactate/pyruvate ratio > 20, was detected without a measurable time delay with 100% sensitivity and 86% specificity. Rejection (n = 8), which was defined as a lactate level > 2.0 mM and a lactate/pyruvate ratio < 20 lasting for 6 or more hours, was detected with 88% sensitivity and 45% specificity. With additional clinical criteria, the specificity was 83% without a decrease in the sensitivity. Rejection was detected at a median of 4 days (range = 1-7 days) before alanine aminotransferase increased (n = 5, P = 0.11), at a median of 4 days (range = 2-9 days) before total bilirubin increased 25% or more (n = 7, P = 0.04), and at a median of 6 days (range = 4-11 days) before biopsy was performed (n = 8, P = 0.05). In conclusion, microdialysis catheters can be used to detect episodes of ischemia and rejection before current standard methods in pediatric liver transplants with clinically acceptable levels of sensitivity and specificity. The catheters were well tolerated by the children, and no major complications related to the catheters were observed.

Washout of 133-xenon as an objective assessment of paranasal sinus ventilation in endoscopic sinus surgery.

Endoscopic sinus surgery (ESS) is today a common method for the treatment of chronic rhinosinusitis. Assessment of the results has been based mainly upon subjective evaluation, and only a few reports present objective measurements. In the present study, the 133-xenon washout technique was used for preoperative and postoperative evaluation of paranasal sinus ventilation in 12 patients selected for ESS. The postoperative half-times (T1/2) of 133-xenon washout were lower in the sinuses with abnormal preoperative half-times (T1/2), especially in the maxillary sinuses, where the postoperative T1/2 was 44 (22 to 150) minutes (median and quartiles, Q1-Q3) as compared with a preoperative T1/2 of 202 (94 to 278) minutes. The postoperative evaluation included a questionnaire and a follow-up visit with endoscopy and measurements of nasal nitric oxide. The results showed that patients who declared a marked reduction in symptoms exhibited significantly improved sinus ventilation. However, no direct correlation was found between improvement in ventilation and symptom improvement. Nine of the 12 patients showed improvement on endoscopy, and these patients also exhibited improved sinus ventilation. The postoperative nasal nitric oxide levels were within the normal range in 11 of the 12 patients; the other patient showed pathological T1/2 values for all paranasal sinuses. The 133-xenon washout technique is thus a method that can be used for objective evaluation of the ventilation of the paranasal sinuses before and after ESS procedures. However, the technique cannot be used to evaluate sinuses with totally obstructed ostia or postoperative sinuses with very wide neoostia, as rapid washout may lead to no activity remaining at the time of measurement.

Effects of oxymetazoline on the ventilation of paranasal sinuses in healthy subjects.

BACKGROUND: Impairment of sinus ostial function is considered an important factor in the pathophysiology of sinus disease. The use of the decongestants such as alpha2-agonists is thought to improve sinus ostial function. Previous studies have shown an effect of alpha2-agonists on maxillary sinus ostial function only when administered in nasal bellows, but not as a nasal spray or nasal drops. The effect of decongestants on ventilation of the frontal and posterior ethmoidal and sphenoidal sinuses has not been studied to date. METHODS: In this study, the 133-xenon washout method was used to determine ventilation for all paranasal sinuses before and after administration of oxymetazoline as nasal drops in eight subjects and from nasal bellows in nine healthy subjects. RESULTS: No significant effect of oxymetazoline on sinus ventilation was seen in either group. CONCLUSIONS: The results indicate that alpha2-agonists do not have any effect on sinus ventilation in healthy subjects. However, one cannot exclude that decongestants improve sinus ventilation in patients suffering from sinus disease and this requires further studies.