ABSTRACT
To investigate the effects of quinine on the electroretinograms (ERGs) of children with cerebral malaria (CM), we recruited subjects during a single malaria season in Blantyre, Malawi. Seventy ERG investigations were performed, on 34 children with CM. Time recorded from completion of the most recent quinine infusion was termed "quinine elapsed time" (QET). In a subgroup of 16 children, whole-blood quinine concentrations were estimated in a sample of capillary blood, for validation. A significant positive association was found between QET and both maximal-response A-wave amplitude (MRAWA; P=.03) and cone A-wave amplitude (P=.04). Longitudinal analysis demonstrated a significant trend of increasing MRAWA with increasing QET (P=.03). Parenteral quinine administered in therapeutic doses to a pediatric population appears to cause a transient depression in photoreceptor function. No evidence of ocular quinine toxicity was found at the therapeutic doses used.
Subject(s)
Antimalarials/pharmacology , Electroretinography , Malaria, Cerebral/drug therapy , Quinine/pharmacology , Retina/drug effects , Retina/physiopathology , Antimalarials/administration & dosage , Antimalarials/adverse effects , Antimalarials/therapeutic use , Child , Female , Humans , Linear Models , Malaria, Cerebral/complications , Male , Quinine/administration & dosage , Quinine/adverse effects , Quinine/therapeutic use , Retina/pathology , Retinal Diseases/complications , Retinal Diseases/pathology , Retinal Diseases/physiopathology , Time FactorsABSTRACT
The pathogenesis of cerebral malaria (CM), a significant cause of death in the tropics, is still not understood. Cerebral blood flow measurements would be important but are difficult under the conditions prevailing in CM clinics in the tropics. With the goal of using optic nerve head (ONH) blood flow (F(onh)) instead of cerebral blood flow to help outcome prediction, we have tested the feasibility of performing F(onh) measurements in comatose CM children, using a portable ocular laser Doppler flowmeter (LDF). Measurements were performed in one eye of each of 13 children (2.7 +/- 1.1 years) during a period of about 8 min. The Vel(onh) (the relative blood velocity), Vol(onh) (the relative blood volume), and F(onh) values were determined for each child from three to five measurements of 2 to 20 s. Average Vel(onh), Vol(onh), and F(onh) values were 0.49 +/- 0.08 kHz, 2.4 +/- 1.06 arbitrary units (a.u.), and 89 +/- 16.8 a.u., respectively. The average coefficients of variation of the flow parameters based on all segments in each child were 13 +/- 9% (range 1-29%) for Vel(onh), 27 +/- 13% (range 3-65%) for Vol(onh), and 23 +/- 12% (range 5-42%) for F(onh). This study demonstrates the feasibility of LDF measurements in CM children. The large range of these coefficients of variations could be due to the presence of fluctuations of ONH blood flow on a short time scale in these neurologically unstable children.
Subject(s)
Laser-Doppler Flowmetry/instrumentation , Laser-Doppler Flowmetry/methods , Malaria, Cerebral/diagnosis , Malaria, Cerebral/pathology , Optic Nerve/blood supply , Child, Preschool , Humans , Infant , Time FactorsABSTRACT
BACKGROUND: In healthy subjects, choroidal blood flow is regulated when the mean ocular perfusion pressure increases. Since capillary vascular beds are altered in diabetic patients, the regulation of choroidal blood flow could be affected by this pathology. PATIENTS AND METHODS: 10 type I diabetic patients without retinopathy (DNR group) and 7 type I diabetic patients with retinopathy (DR group) participated in the study. In NDR and DR groups, choroidal blood flow was measured while patients raised their mean arterial blood pressure by squatting. The results were compared to those of a previous study in normals. Pupillometry was performed at rest on the two diabetic groups and on seven normals during a modification of illumination (white/black screen transition). RESULTS: In the NDR and DR groups, mean ocular perfusion pressure raised by 61 and 50 % during squatting, respectively. Consecutively, choroidal blood flow did not change in NDR as in normals, but increased linearly in DR patients. The white/black screen transition produced an increase of the pupil diameter of 52 and 49 % in normals and NDR patients, respectively, while it increased by only 16 % in the DR patients. CONCLUSIONS: As already shown in healthy subjects, choroidal blood flow is regulated in NDR patients when the ocular perfusion pressure increases. In DR patients, the absence of this control could be due to a failure of the autonomic nervous system, as suggested by pupillometry results.
