Once-daily gentamicin dosing for the preterm and term newborn: proposal for a simple regimen that achieves target levels.

OBJECTIVE: Based on recent safety and efficacy data, combined with the known pharmacokinetic parameters of aminoglycosides in the newborn, once-daily gentamicin should be preferable to the many other dosing regimens currently in use. Although there are growing data to support its use in term newborns, experience with preterm infants is more limited. In our Neonatal Intensive Care Unit, we experienced difficulties regarding complicated dosing regimens, actual dosing errors, and the tendency to check trough and peak levels around the third dose for infants receiving only a 48 hour course. Therefore, we conducted a quality improvement initiative in which we developed and tested a clinical practice guideline for the use of once-daily gentamicin for preterm and term infants that we hoped would yield trough and peak levels in our target range. METHODS: We combined a review of the published English language literature with pharmacokinetic analysis of our own data prior to initiation of this new regimen to design the following dosing regimen: <35 weeks gestation: 3 mg/kg q 24 hours, > or =35 weeks gestation: 4 mg/kg q 24 hours. Our goal serum levels were a trough < or =2 microg/ml and a peak between 6 and 12 microg/ml. We collected and analyzed trough and peak levels from all infants receiving this dosing regimen in the first week of life for at least 72 hours between 3/1/99 and 12/31/00. RESULTS: In total, 214 babies met our inclusion criteria, 75 of whom were <35 weeks gestation. 100% of babies of all gestational ages had a nontoxic trough level. For infants <35 weeks gestation, 79% had a therapeutic peak level, with a mean value of 6.8 microg/ml. For infants of at least 35 weeks gestation, 93% had a therapeutic peak level, with a mean value of 8.4 microg/ml. 92% of nontherapeutic peaks were too low. CONCLUSION: This study of once-daily gentamicin represents the largest sample size of pre-term infants published to date. The proposed regimen is simple and yields a high proportion of desirable levels. We recommend it for use in preterm and term newborns.     

Heart rate and blood pressure variability as markers of sensory blockade with labour epidural analgesia

PURPOSE: To evaluate the correlation between the progression of somatosensory blockade and changes in autonomic outflow following the onset of labour epidural analgesia. METHODS: Twelve labouring parturients consented to participate in the study. Baseline electrocardiogram, blood pressure (BP) and respiratory rate were recorded for ten minutes. The epidural consisted of 0.125% bupivacaine with 50 microg of fentanyl (total volume 20 mL). Measurements were repeated for ten minutes after initiation of the block. The level of sensory block was measured bilaterally with loss of sensation to ice at two-minute intervals. Wavelet transform was used to obtain heart rate (HR) and BP variability every two minutes following the loading dose of epidural medication. High frequency power of HR variability was used to assess changes in parasympathetic activity. The total power of BP variability was used to assess changes in sympathetic activity. A nonparametric repeated measures ANOVA was used for the variability data, and a Spearman rank correlation test was used to evaluate the relationship between the sensory block and HR and BP variability. RESULTS: The sensory block progressed to T9 at ten minutes post-epidural and was the mirror image of the decrease in total power of BP variability. High frequency power of HR variability increased to a plateau at six minutes post-epidural. A significant correlation was found between the increase in sensory block and the observed decrease in BP variability (r = -1.000, P = 0.0028). CONCLUSION: In this study of labouring parturients, BP variability correlated with the progression of both sympathetic and somatosensory block following epidural anesthesia, while HR variability was shown to be a surrogate marker of increased parasympathetic activity.     

THE RELATIONSHIPS BETWEEN SERUM T3 INDEX, THYROID VOLUME, AND THYROID STIMULATING, TSH RECEPTOR BINDING AND THYROID GROWTH STIMULATING ANTIBODIES IN UNTREATED GRAVES'' DISEASE

High plasma concentrations of neuropeptide Y (NPY) were found in a patient with bilateral adrenal phaeochromocytomas and medullary thyroid carcinoma associated with MEN IIa (32 pmol/l, normal less than 3.5 pmol/l). Both adrenal tumours contained and secreted NPY. Manipulation at operation produced a remarkable increase in plasma NPY concentrations (peak = 1631 pmol/l) coinciding with increases in plasma levels of catecholamines and arterial pressure. NPY was also shown to be present in thyroid tumour tissue: the concentration of NPY in tumour was 50-fold higher (0.9 nmol/g vs 0.004 nmol/g) than in adjacent normal thyroid tissue. It is possible that NPY from some phaeochromocytomas may contribute to hypertension during surgery.     

Autoimmune reactions in patients with M-component and peripheral neuropathy.

A study of 17 patients with autoimmune axonal or demyelinating peripheral neuropathy in combination with M-component is described. The M-component was associated with MGUS (monoclonal gammopathy of undetermined significance) in 12 patients, CLL in one patient, WaldenstrÖm's disease in one patient, and myeloma in three patients. Immunohistological examination with direct and indirect fluorescence showed binding of antibodies to nerve structures of the same class and light chain as seen in the M-component. In five cases of IgM M-component, the demyelinating neuropathy was caused by binding of the IgM M-protein and complement C3b to myelin-associated glycoproteins (MAG). In 12 cases with axonal neuropathy, binding of IgG to the connective tissue of the peri- and endoneurium was found in 50% of cases, IgM in five cases, and IgD in one case. None of the patients had central nervous system (CNS) symptoms. The clinical and therapeutic difficulties are discussed; only two patients with an acute course responded to immunosuppression. A marked co-expression of other autoimmune phenomena is interpreted in the light of cross-reactions between the autoantibody and similar tissue autoantigens.     

Self-Concept and Satisfaction With Physical Appearance in Youth With and Without Oral Clefts

This study investigated relationships between child/parent dissatisfaction with child facial appearance and the self-concept/social competence of 8- to 15-year-old children with (N = 34) and without (N = 34) oral clefts. Children in both groups had normative psychosocial adjustment, but also reported moderate dissatisfaction with facial appearance. Cleft group parents were more likely to agree with their child's dissatisfaction. When cleft group parents were more dissatisfied with child facial appearance, their children reported better quality of life. Results suggest that parents of children with clefts reporting greater dissatisfaction may respond in positive ways that enhance quality of life.     

Evaluation of a single-tube multiplex polymerase chain reaction screen for detection of common alpha-thalassemia genotypes in a clinical laboratory

We prospectively compared a single-tube multiplex polymerase chain reaction (PCR) for detecting alpha-thalassemia with our current approach using 452 blood samples. Initial evaluation of 89 specimens revealed sensitivity and specificity, respectively, for the hemoglobin H inclusion body test (HbH prep) vs PCR for detecting alpha0-thalassemia carriers of 0.79 and 0.96 and for a mean corpuscular volume (MCV) of 82 microm3 (82 fL) or less, 1.0 and 0.45. Detection of all alpha-thalassemia genotypes was significantly lower for HbH prep and MCV (sensitivity and specificity, respectively: HbH prep, 0.48 and 0.96; MCV, 0.87 and 0.47). In a follow-up evaluation of patients with positive HbH prep results or suspected alpha-thalassemia prescreened by low MCV, the sensitivity and specificity, respectively, of HbH prep vs PCR increased to 0.97 and 0.93 for alpha0-thalassemia and 0.83 and 0.92 for any alpha-thalassemia. PCR detected alpha-thalassemia in 37.2% of 298 suspected alpha-thalassemia cases with suggestive indices but negative HbH prep results and no detectable hemoglobinopathy. This multiplex approach was more sensitive than the HbH prep for detecting all alpha-thalassemia genotypes, particularly alpha+-thalassemia; was particularly valuable for identifying carriers of alpha0-thalassemia at risk for offspring with hemoglobin Bart hydropsfetalis, regardless of other diagnosed hemoglobinopathies; and is an ideal adjunct to standard clinical screening protocols for detecting alpha-globin deletions.