Systemic Absorption and Block after Epidural Injection of Ropivacaine in Healthy Volunteers

Background: For local anesthetics, the process of removal from the site of administration influences the duration of anesthesia and the risk for systemic toxicity to develop. The systemic absorption of epidural ropivacaine and the time profile of sensory and motor block were studied in healthy volunteers.

Methods: Nine persons simultaneously received 150 mg ropivacaine hydrochloride (7.5 mg/ml) epidurally and 40 mg deuterium-labeled (sup 2 H sub 3)ropivacaine hydrochloride (0.25 mg/ml) intravenously. Peripheral arterial and venous plasma samples were collected, and assessments of sensory and motor block were made.

Results: The arterial plasma concentrations increased faster than the venous concentrations, with 50% higher maximum concentrations after both intravenous and epidural administration. The absorption was biphasic. A correlation was seen between the duration of sensory block and the slower absorption half-life; that is, the longer the half-life, the longer the duration. The extent of spread varied among the volunteers, with the median upper block level not exceeding T12. The motor block (Bromage score 1) was of slower onset (median, 0.4 h) and of shorter duration (median, 4.1 h) than the sensory block (onset, 0.2 h; duration, 6.5 h at L2 medians).     

Effects of residence and race on burden of travel for care: cross sectional analysis of the 2001 US National Household Travel Survey

Background  

Travel burden is a key element in conceptualizing geographic access to health care. Prior research has shown that both rural and minority populations bear disproportionate travel burdens. However, many studies are limited to specific types of patient or specific locales. The purpose of our study was to quantify geographic and race-based differences in distance traveled and time spent in travel for medical/dental care using representative national data.     

A critical period for functional vestibular development in zebrafish.

We have determined a critical period for vestibular development in zebrafish by using a bioreactor designed by NASA to simulate microgravity for cells in culture. A critical period is defined as the briefest period of time during development when stimulus deprivation results in long lasting or permanent sensory deficits. Zebrafish eggs were collected within 3 hours of being laid and fertilized. In experiment 1, eggs were placed in the bioreactor at 3, 24, 30, 36, 48, or 72 hours postfertilization (hPF) and maintained in the bioreactor until 96 hPF. In experiment 2, eggs were placed in the bioreactor immediately after they were collected and maintained in the bioreactor until 24, 36, 48, 60, 66, 72, or 96 hPF. Beginning at 96 hPF, all larvae had their vestibulo-ocular reflexes (VOR) evaluated once each day for 5 days. Only larvae that hatched from eggs that were placed in the bioreactor before 30 hPF in experiment 1 or removed from the bioreactor later than 66 hPF in experiment 2 had VOR deficits that persisted for at least 5 days. These data suggest a critical period for vestibular development in the zebrafish that begins before 30 hPF and ends after 66 hPF. To confirm this, zebrafish eggs were placed in the bioreactor at 24 hPF and removed at 72 hPF. VORs were evaluated in these larvae once each day for 5 days beginning at 96 hPF. These larvae had VOR deficits that persisted for at least 5 days. In addition, larvae that had been maintained in the bioreactor from 24 to 66 hPF or from 30 to 72 hPF, had only temporary VOR deficits. In a final experiment, zebrafish eggs were placed in the bioreactor at 3 hPF and removed at 96 hPF but the bioreactor was turned off from 24 hPF to 72 hPF. These larvae had normal VORs when they were removed from the bioreactor at 96 hPF. Taken as a whole, these data support the idea that there is a critical period for functional maturation of the zebrafish vestibular system. The developmental period identified includes the timeframe during which the vestibular primary afferent neurons are born, innervate their central and peripheral targets, and remodel their central projections.     

Tachycardia''s toll: tachycardia induced cardiomyopathy — a case study

Cardiac arrhythmias are a well known cause of mortality for patients with heart disease. However, sinus tachycardia is a more unusual arrhythmia which can lead to serious heart damage or death. Even young patients with structurally normal hearts may become gravely ill.

This case study outlines the condition of sinus tachycardia, and associated changes in heart function, altered cellular structure of the myocardium and compensatory mechanisms in the body. Treatment modalities, including electro-physiological studies and drug therapies to moderate the tachycardia and myocardial oxygen demand of the heart, are discussed. Fourteen year old ‘Ben’ was previously a well, active and outgoing youth who suddenly became critically ill. He endured weeks of hospitalisation, numerous serious complications including Torsade de pointes arrhythmia, Cheyne-Stokes respirations, nausea and dizziness during this acute phase. Despite challenges, Ben's severely compromised heart muscle recovered at a remarkable rate.     

Traditional Practices of Women From India: Pregnancy, Childbirth, and Newborn Care

This article describes maternal and child care practices among women from India. As in all cultures, certain beliefs exist surrounding what facilitates a good pregnancy and its outcome, as well as negative sanctions. These practices continue to influence many immigrant women to whom western practices are either unknown or unacceptable. An understanding of the traditional belief system of such women can ease their adaptation into the Canadian and U.S. health care systems.