[Design and evaluation of the quality of information written for scanner and magnetic resonance imaging in neuropediatrics]. / Conception et évaluation de la qualité d'une information écrite sur le scanner et l'imagerie par résonance magnétique en neuropédiatrie.

INTRODUCTION: We designed written information concerning two medical imaging techniques: the computed tomography scanner and the magnetic resonance imaging (MRI), and we evaluated the quality of the information in particular its readability. METHODS: Written information concerning scanner and MRI were elaborate starting from a reference frame based on a lexicon of the good practices. The written information sheets were initially reviewed by eight doctors, 45 nurses and by 26 couples of parents of hospitalized children, and finally by the communication and juridical services of our hospital. They were asked to improve the lexico-syntactic readability in order to increase the comprehension of the written information. Seventy-two couples of parents of hospitalized children who had not taken part of the protocol before evaluated the final version of the documents. The quality of the documents was evaluated using the scores of readability of Flesch and the Flesch-Kincaid, and a questionnaire of comprehension, managed before and after the delivery of written information. RESULTS: A total of 144 persons participated in the study. The number of right answers after reading written information increased by 38 % and by 35 % for the scanner and MRI information's respectively. Flesch and Flesch-Kincaid scores were not improved in the revised version of the written information compared to the first version. CONCLUSION: Although readability scores for information sheets were low, our results suggest that they brought information, which contributed to a better understanding of these two medical imaging techniques by parents.

Assessing erectile neurogenic dysfunction from heart rate variability through a Generalized Linear Mixed Model framework.

BACKGROUND: The low (LF) vs. high (HF) frequency energy ratio, computed from the spectral decomposition of heart beat intervals, has become a major tool in cardiac autonomic system control and sympatho-vagal balance studies. The (statistical) distributions of response variables designed from ratios of two quantities, such as the LF/HF ratio, are likely to non-normal, hence preventing e.g., from a relevant use of the t-test. Even using a non-parametric formulation, the solution may be not appropriate as the test statistics do not account for correlation and heteroskedasticity, such as those that can be observed when several measures are taken from the same patient. OBJECTIVES: The analyses for such type of data require the application of statistical models which do not assume a priori independence. In this spirit, the present contribution proposes the use of the Generalized Linear Mixed Models (GLMMs) framework to assess differences between groups of measures performed over classes of patients. METHODS: Statistical linear mixed models allow the inclusion of at least one random effect, besides the error term, which induces correlation between observations from the same subject. Moreover, by using GLMM, practitioners could assume any probability distribution, within the exponential family, for the data, and naturally model heteroskedasticity. Here, the sympatho-vagal balance expressed as LF/HF ratio of patients suffering neurogenic erectile dysfunction under three different body positions was analyzed in a case-control protocol by means of a GLMM under gamma and Gaussian distributed responses assumptions. RESULTS: The gamma GLMM model was compared with the normal linear mixed model (LMM) approach conducted using raw and log transformed data. Both raw GLMM gamma and log transformed LMM allow better inference for factor effects, including correlations between observations from the same patient under different body position compared to the raw LMM. The gamma GLMM provides a more natural distribution assumption of a response expressed as a ratio. CONCLUSIONS: A gamma distribution assumption intrinsically models quadratic relationships between the expected value and the variance of the data avoiding prior data transformation. SAS and R source code are available on request.

[From the creation to the appreciation of a personal digital assistant-based clinical decision-support system for the management of artificial nutrition]. / De la conception à l'évaluation d'un programme d'aide à la prescription en nutrition artificielle sous Palm OS.

OBJECTIVES: The aim of our study was to assess the effect of NutriPDA, a personal digital assistant (PDA)-based clinical decision-support system (CDSS) for the management of artificial nutrition. A CDSS was developed and implemented on a handheld computer for use in the ICU after cardiovascular and thoracic surgery. STUDY DESIGN: System impact was assessed in a prospective "before/after" cohort trial. METHODS: After informed consent we studied 61 patients in the postcardiovascular and thoracic surgery ICU (age > 17 years, duration of artificial nutrition > 3 days, length of stay > 8 days). Patients were divided into two groups (before and after the use of NutriPDA: Group A: 32 patients (4-month period in 2005); group B: 29 patients (4-month period in 2006). RESULTS: There were no significant differences in anthropometric and clinical parameters between the 2 groups. Energetic intakes were < 80% of basal energetic expenditures in 21% and 1% of patients, respectively (P < 0.01). Caloric and nitrogen intakes were below international recommendation in Group A: 20+/-4 kcal/kg/d (mean+/-SD), 104+/-30 mg/kg/d, but not in Group B: 26+/-5 kcal/kg/d, 196+/-41 mg/kg/d (P < 0.01). CONCLUSION: NutriPDA was found to be able to optimize artificial nutrition by improving caloric intake in ICU. This new software has potential clinical applications.

[From the creation to the appreciation of a pedagogic Internet site in anaesthesia and intensive care]. / De la création à l'évaluation d'un site Internet pédagogique en anesthésie-réanimation.

OBJECTIVES: The aim of this study was to conceive, create, validate and assess a pedagogic site to teach students. STUDY DESIGN: Survey with questionnaires. METHODS: First, we performed an educational need assessment in that field, conducting a review of legal regulations and international guidelines and a survey of 91 students. Afterwards, we drew up a reference document based on proven scientific data, with selected bibliography and we wrote a list of specific teaching objectives. We then created a pedagogic Web site including illustrated references, documents, a selected bibliography and useful Internet links. These pedagogic Web sites could be associated to well-conducted tutorial sites by qualified senior physicians in an academic process to improve procedural skill teaching. After internal and external validation, this educational Web site was evaluated by students. This evaluation used the questionnaire proposed by "Régie Régionale de la Santé et des Services Sociaux de Montréal" (regional authority control of health and social services of Montreal). Our pedagogic Web site obtained 76 out of 100 and can be considered satisfactory. CONCLUSION: This study demonstrated that adapted multimedia tools can improve procedural skill teaching in anaesthesia and intensive care.

Assessment of cardiovascular autonomic control by the empirical mode decomposition.

OBJECTIVES: Heart-rate variability (HRV) is an interesting tool for assessing cardiac autonomic system control, but nonstationarities raise problematic issues. The objective of this paper is to show that adapted signal processing tools may cope with nonstationary situations and improve the analysis of HRV. METHODS: We propose to use the recent method of Empirical Mode Decomposition (EMD), so as to analyze the cardiac sympatho-vagal balance on automatically extracted modes. The method, which is fully data-adaptive, consists in an iterative decomposition based on the idea that any signal can be locally represented as an oscillation superimposed to a more regular trend. When a signal is composed of distinct nonstationary components, EMD therefore achieves a time-varying filtering which effectively separates them. RESULTS: The method has been applied to situations where postural changes occur, provoking instantaneous changes in heart rate as a result of autonomic modifications. In the considered application where the sympatho-vagal balance is quantified by comparing the low-frequency (LF) and high-frequency (HF) components of RR intervals, EMD automatically achieves a separation of these components upon which further processing can be carried. Visualizing the decomposition in the time-frequency plane, we can identify local events due to the postural changes, and we can assess a (time-varying) HF vs. LF discrimination without resorting to some fixed high-pass/low-pass filtering. CONCLUSION: Assessing cardiovascular autonomic control by resorting to LF/HF measurements may prove difficult in nonstationary situations where the use of a priori fixed filters can be questioned. Because it is both local and fully data-adaptive, EMD appears as an appealing and versatile pre-processing technique for overcoming some of the limitations that conventional spectral methods are faced with in nonstationary situations.

[To understand blood pressure and heart rate variability]. / Comprendre la variabilité de la pression artérielle et de la fréquence cardiaque.

OBJECTIVES: To review current data on the heart rate and blood pressure variability. DATA SOURCES: Search through Medline databases of articles in french or english. DATA SELECTION: Original articles and case reports were selected according to their quality and main advances. The articles were analysed in order to obtain current data about the methods of study and clinical application of blood pressure and heart rate variability. DATA SYNTHESIS: Various regulatory systems in the cardiovascular system play crucial roles in controlling and assuring adequate perfusion of the peripheral tissues. Among them the baroreceptor reflex is the most important regulatory mechanism in the short-term control of the heart rate and blood pressure, and operates through the autonomic nervous system. The gain of the cardiac baroreflex further referred to, as baroreflex sensitivity is an interesting way to study this system. Unfortunately, with our current knowledge, it is not possible to predict the instantaneous output of the baroreceptor in response to instantaneous changes in input within a frequency range of physiological importance. The fast Fourier transform can describe variables as the sum of elementary oscillatory components and it has been established as practical clinical methods for detecting abnormalities in cardiovascular control. A time-frequency distribution provides an indication of how the spectral energy distribution varies with time and it is an interesting tool in non-stationary data. One of the major motivations behind spectral analysis is the hope that the combination of time-domain and frequency-domain analyses will provide dynamical informations about the relation between blood pressure and heart rate.

[Fulminant mediastinitis from Streptococcus pneumoniae following cardiac surgery]. / Médiastinite fulminante à Streptococcus pneumoniae après chirurgie cardiaque.

A 62-year-old patient was scheduled for coronary artery bypass surgery because of tritroncular coronary artery disease. The early postoperative period was uncomplicated until the 10th postoperative day when purulent fluid appeared from the sternal wound. Cultures of blood, wound and mediastinal tissues yielded Streptococcus pneumoniae with decreased susceptibility to penicillin G. Despite prompt surgical debridement and appropriate antibiotics, a septic shock with multiorgan failure occurred and the patient died on the 19th postoperative day. Although Streptococcus pneumoniae is uncommonly implicated in postoperative mediatinitis, it frequently leads to multiple organ failure and death.

Effect of alpha-adrenoceptor blockade on the 0.4 Hz sympathetic rhythm in conscious rats.

1. The present study examined the origin of the 0.4 Hz rhythm in renal sympathetic nerve activity (RSNA) in rats. It was anticipated that, after elimination of 0.4 Hz oscillations of arterial pressure (AP) by alpha-adrenoceptor blockade, the persistence or disappearance of a 0.4 Hz rhythm in RSNA would point to an endogenous (central oscillator) or baroreflex origin, respectively. 2. Arterial pressure and RSNA were recorded in seven conscious rats, before and after acute alpha-adrenoceptor blockade with phentolamine (5 mg/kg, i.v.). In each condition, power and coherence spectra were calculated over 15 min periods of rest. 3. In control conditions, highly coherent AP and RSNA oscillations were observed near 0.4 Hz. After phentolamine administration, spectral power in the mid-frequency (0.27-0.74 Hz) band was significantly reduced for both AP and RSNA and maximum power was shifted towards 0.7 Hz. 4. The disappearance of the RSNA rhythm at 0.4 Hz after phentolamine administration favours the hypothesis of a baroreflex origin. The new oscillation near 0.7 Hz can derive either from the activity of a previously unrecognized central oscillator or from a faster feedback mechanism involving cotransmitters of noradrenaline acting with shorter time constants (e.g. ATP).

Influence of temperature on tracheal tube cuff pressure during cardiac surgery.

BACKGROUND: Lateral wall pressure may cause tracheal injury by affecting tracheal capillary blood flow. Damage to the trachea is less severe when lateral wall pressure exerted by the endotracheal tube cuff does not exceed the mean capillary perfusion pressure of the mucosa. The purpose of this study was to determine the effects of hypothermic and normothermic cardiopulmonary bypass (CPB) on tracheal tube cuff pressure dynamics. METHODS: Twenty-two patients were studied during normothermic CPB (pulmonary artery blood temperature in the CPB period between 36 and 35 degrees C), and 22 patients during hypothermic CPB (pulmonary artery temperature in the CPB period between 32 and 28 degrees C). A Mallinckrodt Medical Lo-Contour Murphy tracheal tube, with high-volume, low-pressure cuff was used without lubricant. Intracuff pressure (ITCP) was recorded at end-expiration before, during and after cardiopulmonary bypass. RESULTS: ITCP measurements were different between groups during CPB at aortic cross-clamping (13.9 +/- 0.8 mmHg in the normothermic group versus 11.3 +/- 0.4 mmHg in the hypothermic group, P < 0.05), and respectively during CPB after aortic declamping (15.3 +/- 0.8 mmHg and 12.6 +/- 0.8 mmHg, P < 0.05) and after CPB at the end of surgery (16.8 +/- 0.7 mmHg and 18.6 +/- 0.3 mmHg, P < 0.05). CONCLUSION: We conclude that the ITCP is higher in normothermic CPB than in hypothermic CPB; however, the clinical significance of this observation needs further investigation.

Brachial plexus injury during cardiac catheterisation in children. Report of two cases.

The arm is particularly vulnerable to neurological injury, due to the intimate anatomical relationship between the brachial plexus and the traction zones. Severe injuries of the brachial plexus can be caused by compression, traction or laceration. Fortunately, many deficits are superficial and permanent neurovascular deficits are rare. Nevertheless, it is important to identify the probable cause of the injury since the prognosis for recovery directly depends on the underlying nature of the neurological deficit. Two anaesthetised children who suffered brachial plexus injury during cardiac catheterisation are reported. The first, with Ebstein's anomaly and significant pulmonary valve stenosis, presented, after the procedure, with a right arm motor deficit with proximal predominance. The second patient, with tetralogy of Fallot and pulmonary atresia, presented difficulty in left arm abduction and external rotation on awakening. The risk factors for brachial plexus lesions during anaesthesia are discussed. These include improper positioning, anaesthetic agents, extreme variations of body mass index and anatomical anomalies. Prevention, evolution and treatment of the brachial plexus injury are also considered. With proper care by the cardio-radiologist and anaesthesiologist the frequency of this injury can be reduced.