Biomedical subjects

M C Guertin

Publications and source records attributed to M C Guertin.

6 recordsLinked to original sources

PubMed1997

Should we patch corneal erosions?

OBJECTIVE: To study the effect of patching on the speed of reepithelialization, slit-lamp signs of epithelial wound healing, and patient discomfort following a corneal abrasion. METHODS: Forty-eight eyes of 46 patients with corneal erosion sparing Bowman membrane were randomized into 2 groups: with or without patching. Slit-lamp examination and photographs of the fluorescein-stained cornea were performed on a daily basis until reepithelialization was complete. Photographs were analyzed using computer-assisted planimetry. RESULTS: No statistically significant difference was found between patched (n = 25) and nonpatched (n = 22) eyes for the mean size of the initial erosion (patched eyes, 23.7 mm2; nonpatched eyes, 18.9 mm2; P = .42), linear speed of reepithelialization (reduction over time of the radius of the largest circle included in the erosion: patched eyes, 0.0375 mm/h; nonpatched eyes, 0.0353 mm/h; P = .78), and surface speed of reepithelialization (reduction over time of the erosion area: patched eyes, 0.6510 mm2/h; nonpatched eyes, 0.5657 mm2/h; P = .60). The power to detect a 12-hour delay of epithelial closure was 95%. There were no significant differences between the 2 groups for pain, analgesia, insomnia, aspect of the epithelial border, intensity and duration of stromal edema, Descemet folds, anterior uveitis, and filaments. CONCLUSIONS: Patching a corneal erosion does not significantly accelerate reepithelialization and does not alter the epithelial wound healing pattern. It does not reduce the incidence and severity of inflammation nor relieve pain when compared with treatment without patching.

Adult↗

PubMed1997

Study of psychosocial parameters related to the survival rate of renal transplantation in children.

The purpose of the present study was to assess the effect of intelligence, schooling, psychomotor, emotional, and social status on renal graft survival in children. Sixty-two cadaver renal transplant recipients were evaluated retrospectively and the influence of sex, age, weight, and the use of cyclosporin A (CyA) on the success rate of the graft from 1 to 5 years later was analyzed. Psychological and social scores were devised and included as factors predictive of survival of the graft. Univariate analysis showed that the following variables predicted renal graft survival: the use of CyA (P = 0.0002), pre-transplant dialysis (P = 0.04), weight at the time of transplantation (P = 0.072), and psychological scores (P = 0.064). Association analysis demonstrated that pre-transplantation dialysis was only a chance association and therefore the parameter was discarded. Multivariate analysis showed that the predictive parameters were the use of CyA, sex, weight in kilograms, and the psychological score. An equation was then derived from variables that predict the probability that a specific patient's graft will survive more than t months. This equation is the estimated survival distribution function and is as follow: S (t) = Exp {-Exp[-(0.8882x1 - 1.827x2 + 0.037x3 - 0.1746x4) + ln t - 4.7862]} where S (t) = the survival at t months post transplantation, x1 = sex (male 1, female 2), x2 = CyA (yes 1, no 2), x3 = weight in kilograms, and x4 = psychological score. The major impact of psychological factors on renal graft survival was surprising.

Adolescent↗

PubMed1996

Anterior stromal punctures for bullous keratopathy.

OBJECTIVE: To evaluate the therapeutic effects of anterior stromal punctures (ASP) in patients with bullous keratopathy (BK). PATIENTS AND METHODS: Twenty-seven patients awaiting penetrating keratoplasty with a diagnosis of BK were examined. They were seen before treatment with ASP and 1, 4, and 12 weeks after treatment. The examination included slit-lamp examination, photography of the cornea, ultrasonic pachymetry, central esthesiometry, and pneumotonometry. Subjective evaluations of pain, discomfort, and photophobia were also done using a visual scale model. Photographs were analyzed by computer-assisted planimetry and used to measure the corneal surface covered by bullae and microcysts. Pretreatment and posttreatment values (mean +/- SEM) were compared using the Student paired t test. RESULTS: At 3 months, a significant reduction in pain was noted. A decrease in the mean corneal surface covered by bullae (BKPreASP = 2733 +/- 553 microns2; BK3mo = 1006 +/- 356 microns2, P = .004) was observed. A decrease in the esthesiometry (E) measurement (EPreASP = 3.5 +/- 0.4 cm; E3mo = 1.3 +/- 0.3 cm, P < .001), an increase in corneal thickness ([CT] CTPreASP = 869 +/- 24 microns; CT3mo = 902 +/- 21 microns, P < .001), and a decrease in the number of quadrants through which iris (I) details could be seen (IPreASP = 1.7 +/- 0.3; I3mo = 1.2 +/- 0.3, P = .015) were also noted. These findings corroborate the clinical observation of increased subepithelial fibrosis following ASP. CONCLUSIONS: Anterior stromal punctures reduce bullae formation and alleviate pain in patients with BK, and they constitute a valuable alternative to penetrating keratoplasty should surgery be delayed or contraindicated.

Adult↗

PubMed1995

Reference values obtained by kernel-based estimation of quantile regressions.

In this paper, we study the problem of estimating non-parametrically a quantile regression curve as it applies to computing reference values. We propose an automatic procedure that uses a symmetrized nearest-neighbor kernel estimator of conditional distributions. We also discuss ways of measuring the dispersion of quantile regression estimator. One is based on the asymptotic distribution of such quantiles, while the other relies on the bootstrap method. The results of a small simulation study show that the methods of the paper perform rather well even in a situation where a good parametric solution is available. As an example, we analyze a small part of a data set that was collected to establish reference values for blood velocity in different parts of the umbilical cord of human fetuse as they grow toward birth.

Biometry↗

PubMed1994

Predicting blood loss in surgery for idiopathic scoliosis.

The authors attempted to determine the relative importance of factors that influence bleeding during and after spinal fusion. Data from 30 ASA I patients with idiopathic scoliosis were prospectively collected and analyzed. Intraoperative bleeding was 1971 +/- 831 ml (mean +/- SD) (61.5 +/- 27% of estimated blood volume (EBV) and correlated with the number of fused vertebrae (r = 0.66, P < 0.0001) and the duration of surgery (r = 0.46, P = 0.0105). There was no correlation between intraoperative bleeding and the Cobb curve angle (43 to 86 degrees), the mean arterial blood pressure (MAP) (63 to 86 mmHg), the central venous pressure (CVP), the quantity of epinephrine infiltrated, muscle relaxants or opioids used, nor in the type of opioids used, the minimal body temperature or whether stored or autologous blood was used. Postoperative bleeding was 1383 +/- 369 ml (43.1 +/- 11.7% of EBV) and correlated with the length of time the Hemovac drain was in place (r = 0.40, P = 0.0285) and MAP (r = 0.40, P = 0.0285). There was no correlation between postoperative and intraoperative bleeding nor in the number of fused vertebrae. Six patients had greater postoperative than intraoperative bleeding. The total bleeding (intra- plus postoperative) was 3347 +/- 920 ml (104.2 +/- 30.6 of EBV) and correlated with the number of fused vertebrae (r = 0.63, P = 0.0001) and with the duration of surgery (r = 0.42, P = 0.0208). We conclude that the number of fused vertebrae is the key factor in predicting intraoperative and total bleeding. Postoperative bleeding is considerable (up to 76.9% of EBV).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Reference values for Doppler velocimetric indices from the fetal and placental ends of the umbilical artery during normal pregnancy.

A range-gated Doppler ultrasound system combined with a real-time imaging system was used to determine arterial blood velocity values from the fetal and placental ends of the umbilical cord in 269 normal pregnancies between 17 and 40 weeks, menstrual age. The systolic-diastolic ratio (S/D), pulsatility index (PI), and resistance index (RI) were higher at the fetal end compared to the placental end of the cord. The individual differences in these Doppler indices, obtained between the fetal and placental recording sites, were inversely related to menstrual age: S/D: r = -0.38, p < 0.001; PI: r = -0.25, p < 0.001; and RI: r = -0.15, p < 0.01. After normalization for the angle of insonation, the peak systolic velocity was higher and the end-diastolic velocity was lower at the fetal than at the placental end of the cord. It is concluded that routine recordings for Doppler velocimetric indices should take into account the recording site on the umbilical cord in order to reduce methodological sources of variance, especially during midgestation. Furthermore, the data presented here in the form of the median and percentile values are proposed as normal reference values to facilitate this procedure.

Blood Flow Velocity↗