Delivery and monitoring of inhaled nitric oxide

Inhaled nitric oxide is rapidly gaining popularity as a selective pulmonary vasodilator in patients with acute lung injury and pulmonary hypertension. The development of nitric oxide as a drug has bypassed the usual regulatory and commercial processes, and as a result clinicians have devised a wide range of delivery and monitoring systems. This review describes these systems, and discusses their advantages, disadvantages and safety. The monitoring of nitric oxide metabolites is also discussed.     

Determination of free valproic acid: evaluation of the Centrifree system and comparison between high-performance liquid chromatography and enzyme immunoassay.

Valproic Acid (VPA) is an important drug for the treatment of several types of seizures because it has a wide spectrum of activity. Since VPA has an unusual nonlinear binding characteristic and a wide interindividual variation, monitoring of its free concentration can be helpful in patient management. The determination of unbound VPA is more difficult because an extra sample preparation step is needed and the concentration of free VPA is low. Free drug monitoring can assume a more important role if there is a refinement in the technology. A high-performance liquid chromatography (HPLC) method with isocratic elution has been established for the analysis of the 4-bromomethyl-7-methoxycoumarin (BrMMC) derivative of free VPA. This method has a better sensitivity, linearity, and precision than enzyme immunoassay (EIA). Ultrafiltration with the Centrifree system was evaluated for the sample preparation. The influence of centrifuge times, relative centrifugal forces, and the starting sample amounts on the final results of the ultrafiltration were investigated. There was a satisfactory correlation between the free VPA levels determined by the HPLC method and the concentrations obtained by EIA. The total and free VPA were determined on 100 samples from 36 patients. The total VPA levels were in a range of 25 to 208 micrograms/ml, free VPA concentrations ranged from 1.92 to 55.75 micrograms/ml with the free fractions from 7 to 37%.     

Use of breath hydrogen to quantify carbohydrate malabsorption: Lack of effect of soluble fibre (guar)

Breath H2 has been used for several years to quantify carbohydrate malabsorption. Dietary fibre, particularly fermentable fibres such as guar, may influence breath hydrogen and reduce the validity of this test. Therefore we studied, in healthy subjects over 12 hour periods, the effect on breath hydrogen of taking 15g guar either alone, with food, or with lactulose. Guar alone did not significantly increase breath H2 levels compared to fasting, nor did it increase breath H2 responses when added to test meals of white bread or lactulose. However, guar delayed mouth to caecum transit time from 2.25±0.37 hrs for lactulose alone to 4.0±0.53 hrs for guar plus lactulose (p<0.05). After 15g lactulose was consumed in divided doses over 5 hrs to mimic the delayed transit caused by guar, the peak breath H2 level was reduced by 32% (p<0.02), but total breath H2 was no different from 15g guar added to 15g lactulose. We conclude that guar is not likely to have a significant impact on carbohydrate malabsorption calculations based on the breath H2 technique.     

Laboratory analysis of cerebrospinal fluid.

OBJECTIVE. To review the physiology of cerebrospinal fluid (CSF), normal laboratory reference values, and key aspects of CSF sample collection, gross and microscopic examination, microbiologic testing, and chemical analysis. DATA SOURCES. Recent professional literature. STUDY SELECTION. Selected manually by the authors. DATA EXTRACTION. Articles manually by the authors. DATA SYNTHESIS. CSF is formed by a combined process of plasma ultrafiltration and active secretion. Mechanical and osmotic barriers exist between plasma and CSF and between CSF and brain. Lumbar puncture is the preferred technique for CSF sampling. Normal CSF should be clear, colorless, and free of clotted material. CSF can be examined for presence of microbes using stains. Additionally, the chemical composition of CSF can be examined; tests of interest include glucose, protein, lactate, enzymes, glutamine, specific amino acids, biogenic amines, and various drugs. CONCLUSION. Visual, microscopic, and chemical examination of CSF is essential to the clinical management of patients with CNS disease.     

Evaluation of the prognostic value of the health assessment form among patients clinically ready for discharge

The aim of the study was to identify patterns of physical, psychological, and social conditions that may be of prognostic value when it comes to assessing continued care of patients clinically ready for discharge; a related aim was to evaluate instruments used for this identification, especially a Swedish version of the health assessment form. The sample consisted of 53 consecutive patients (mean age 82.8 years, SD = 6.6 years) All patients came from their own homes and were admitted to surgical and orthopaedic departments. Interviews were carried out on the day the patients were assessed as medically ready for discharge, and a second time 1 month later. The health assessment form measured the persons' social and environmental situation, health history, and functional health status, and another instrument measured the persons' sense of coherence. Few significant differences in functional health status were noted between persons who could return to their homes (n =25) and persons who were referred to institutions after discharge (n = 17). However, the persons being referred to institutions showed less favourable scores within the areas of mood, sense of coherence, and worries about their home accommodation situation. When another sub-group was included (patients who died between the interview occasions; n = 8), significant differences were also noted in the health functions breathing, digestion, elimination, and body movement. Sense of coherence had a significant prognostic value for the continued care after discharge irrespective of whether the deceased patients were included or not.     

Maternal and neonatal characteristics following exposure to cocaine in Toronto

We prospectively ascertained gestational cocaine use by neonatal urine and hair tests in 600 mother infant pairs in 3 nurseries in Toronto. The 37 (6.25%) babies who tested positive for cocaine and their mothers were compared to the 563 nonexposed with regard to pregnancy outcome and neonatal complications. Mothers using cocaine were not different in their ages, racial distribution, and obstetric history from those nonexposed. Cocaine-using women had significantly higher risk for vaginal bleeding (16% vs 6%, P < 0.05), hepatitis B carrier state (8% vs 0.8%, P < 0.005), and perhaps more urinary tract infections (8% vs 2.5%, P = 0.08). cocaine-using mothers were significantly more likely to smoke cigarettes (29% vs 10%, P < 0.001). Infants exposed to cocaine in utero were of lower birth weight (3162 ± 645 [SD] g vs 3391 ± 573, P < 0.05) and birth length (49.9 ± 2.9 cm vs 51.1 ± 3.1 cm, P < 0.05). Further stratification of babies exposed to cocaine by maternal cigarette smoking suggests that cigarette smoking accounted for most of this variability [birth weight of babies exposed to cocaine and cigarettes 2899 ± 7.50 g (and 50% of them weighed less than 2500 g), vs 3423 ± 612 (and only 8% less than 2500 g) in those exposed to cocaine only (P < 0.05). Babies exposed to cocaine in utero were significantly more likely to need initial medical support or resuscitation (52% vs 30%, P < 0.05). We conclude that gestational exposure to cocaine, ascertained by a sensitive biologic marker, is associated with substantial perinatal risks. It is probable that some of these risks are caused by clustering of other risk factors such as maternal smoking and hepatitis carrier state. Because routine clinical markers and urine testing often fail to distinguish fetal exposure to cocaine, more common use of the hair test should be considered, especially for babies with complicated perinatal courses.