[External Quality Assessment of Thick and Thin Blood Smear Slides for the Diagnosis of Malaria in the Lomé and Gulf Health Districts of Togo]

Objective

In sub-Saharan Africa where 90% of malaria cases are concentrated, the control of this disease constitutes a major challenge whose diagnosis by thick and thin smear deserves to be exact and reproducible. The purpose of this study is to assess the performance of thick/thin blood smear in order to improve its implementation process.

Material and methods

This was a descriptive and analytical study that took place from May to June 2017 and involved participating laboratories (PL) coming from public, liberal and confessional sectors in Lomé. A set of 13 blood smear slides of variable parasite densities (PD) with assigned values (AV) of parasite densities and the Plasmodium species assigned was used. The criterion for establishing the parasite densities compliance interval was assigned values ± 25% and the performance rates were compared to the 80% recommended by the WHO for Africa region.

Results

41.9% (13/31) of the PLs had a compliance rate greater than 80% including four with a performance of 100% for the ability to identify the Plasmodium species. For the parasitaemia < 100/μl, 51.6% of participating laboratories had a performance rate less than 80% and for parasitaemia > 2000/μl, 100% of these laboratories had a performance rate greater than 80%.

Conclusion

The evaluated laboratories had insufficient ability for the identification of Plasmodium falciparum and the correct estimation of low parasitaemia. A need to strength the technical skills, adapted to the context of low parasitaemia are essential to improve the biological diagnosis of malaria in Togo.

[Serologic markers used for hepatitis B surveillance in Togo: status report and action proposals]

The hepatitis B surface antigen (HBsAg) is the only marker used for diagnosis and follow-up of hepatitis B infection in Togo. The purpose of this study was to evaluate the use of HBsAg testing for follow-up of hepatitis B infection. This study was conducted in 230 patients referred to the National Institute of Hygiene for HBsAg testing. In all cases the requested test was performed and the request and results were evaluated.

RESULTS

The study group included 159 women (69%) and 71 men (31%). The overall prevalence of HBsAg was 10.87%. Prevalence was higher in men than in women. Highest prevalence rates were observed in the age groups 20 to 50, which corresponds to the peak period of sexual activity. The indication for testing was often not clearly specified by Laboratory engineers (85.71%), Clinical officers (73.68%) and physicians (61.24%). When mentioned, the indication was suspicion of hepatitis B (20.87%), work-up for pregnancy (8.70%), testing prior to vaccination (8.26%) and surveillance of an infected patient (1.30%). The prevalence of HBsAg was 0.00% in prevaccination tests, 5% in pregnancy workup tests, and 10.42% in hepatitis B suspicion tests. Test results were negative in one infected patient referred for follow-up. None of the patients with positive results returned for therapeutic follow-up testing and no marker other than HBsAg was requested regardless the indication.

CONCLUSION

the laboratory of serology is under-used for hepatitis B surveillance. Hepatitis B follow-up using antigen HBsAg alone is inadequate and the equipment required for testing other markers is the same.

[Effectiveness of a short-stay observation unit in a pediatric emergency department]

Short-Stay Observation Units (SSOUs) in paediatric emergency departments are effective in reducing inpatient admissions but can also generate excessive short-stay hospitalisations. The aim of the study was to evaluate both these consequences and the different missions of SSOUs.

METHODS

This prospective study included all children admitted in a 10-bed-medico-surgical SSOU of a tertiary-care paediatric emergency department from September 4, to October 31, 2001. At the time of SSOU admission, the physician indicated the purpose of the admission and which decision he would have made in the absence of a SSOU.

RESULTS

Five hundred and nine children (median age = 4 years, chronic disease: 26%, trauma: 34%) were included, accounting for 15% of admissions. The mean length of stay was 14 +/- 8h. The decision in the absence of a SSOU would have been: inpatient hospitalization (77%), transfer to another hospital in the absence of inpatient room vacancy (7%), discharge home (10%), prolonged waiting in the emergency ward (4%), do not know or not indicated (2%). The SSOU admission was deemed appropriate in 81%: discharge home within 24h was likely in 65% and the final orientation of the child was uncertain in 16%. The admission was debatable in 13% and inappropriate in 6%. Sixty six per cent of children were discharged home.

CONCLUSION

The SSOU reduced inpatient hospitalisations, generated few inappropriate short stay hospitalisations, and seemed particularly efficient for paediatric diseases. Proposed indicators should allow inter-hospital comparisons.

Plastic bronchitis mimicking foreign body aspiration that needs a specific diagnostic procedure

OBJECTIVE

To report two children admitted to our emergency department with respiratory failure, one for status asthmaticus with pneumomediastinum and requiring mechanical ventilation and the other for high suspicion of foreign body aspiration.

INTERVENTIONS

Bronchoscopy revealed obstructive plugs and permitted their extraction and their identification as bronchial casts after the immersion in normal saline. Allergy was suspected in the first one, and Hemophilus influenzae infection was present in the second. The outcome was favorable.

CONCLUSIONS

Plastic bronchitis is an infrequent cause of acute life-threatening respiratory failure that can mimic foreign body aspiration or status asthmaticus. Bronchoscopic extraction must be performed urgently in the case of severe obstruction. This entity is probably underestimated as the casts with their specific ramifications are difficult to recognize. We recommend the immersion in normal saline of all plugs discovered in children with predisposing diseases mainly represented by infections, allergy, acute chest syndrome, and congenital cardiopathies.

[Life-threatening Plasmodium falciparum parasitemia, in an infant returning from the tropics]

INTRODUCTION

Severe falciparum malaria is a polymorphous life-threatening disease. Hyperparasitemia is rare among non-immune children returning from tropical areas. CARE REPORT: We report a case of an infant returning from Ivory Coast who presented with fever, prostration and marked thrombocytopenia (22,000 platelets/mm(3)). Blood slide showed Plasmodium falciparum ring forms. Parasite density dramatically increased from 1.7% to 45%, and the child developed several features of severe malaria, according to WHO definition.

CONCLUSION

In this non-immune infant, prostration and thrombopocytopenia seemed to be earlier predictors of severity than hyperparasitemia and other WHO criteria, which have not been yet validated in travelling children.

[Multi-parameter indices of weaning from mechanical ventilation in children]

Simple clinical markers have poor sensitivity; specificity and predictive value in both infants and adults when predicting the success of weaning from mechanical ventilation. Recently, multi-parametric indices, such as the CROP (Compliance-Respiratory Rate-Oxygenation-Pressure) and the RSB (Rapid-Shallow-Breathing) have been used in adults and subsequently in children. The aim of this study was to test the value of the pediatric CROP and RSB (CROPp, RSBp) and the accuracy of a simplified pediatric CROP (CROPpS) that does not require an arterial blood gas sample.

MATERIALS AND METHODS

This prospective study was conducted in a pediatric ICU which does not admit neonates. All infants were intubated and ventilated at the time of entry. Spontaneous tidal volume and maximal negative inspiratory pressure, that are required to assess and calculate the indices, were measured using a Fleish pneumotachograph and a unidirectional valve. The other parameters were recorded or calculated. A maximum 4 hour-duration trial of spontaneous ventilation was then performed. Weaning failure was defined as the requirement of re-ventilation within 48 hours of extubation. The discriminant power of CROPp and RSBp was determined by calculating the area under the receiver operating characteristic (ROC) curve. The best cut-off value of the CROPpS was determined by chi2 optimisation.

RESULTS

39 children (20 males) were included in the trial. They had a median age of 3.2 years and a median duration of mechanical ventilation of 1.3 days. 89.7% of children were successfully weaned of mechanical ventilation. Sensitivity of CROP, and RSB, was 97% and 94%, specificity was 0% and 0%, positive predictive value was 89% and 89%, and negative predictive value was 0% and 0% respectively; the area under the ROC curve was 0.57 and 0.74. The CROP,S was found to be as accurate as the CROP, index using the same cut-off value. Comparison of the 2 groups (success, failure) revealed a significant difference in duration of ventilation (longer in the failure group).

CONCLUSION

Even though they correctly classified 87% and 85% of patients respectively, the CROPp and RSBp are not good predictors of weaning from mechanical ventilation as the area under the ROC curve is less than 0.80. Other indices need to be evaluated.

[Treatment of meningococcal purpura fulminans]

In France, the incidence of meningococcal infections is increasing. The most severe presentation, called purpura fulminans, has a death rate of 20-25%; 5 to 20% of the survivors need skin grafts and/or amputations. Diagnosis of invasive meningococcal infection is very difficult when purpura and "toxic" appearance are absent: one should take into account parents' impression of their ill child. This diagnosis must be evoked in any child presenting with febrile purpura (like in the United Kingdom, parents should be encouraged to use the "tumbler test" to identify a vasculitic rash); a fulminant form is to be suspected in the presence of only one ecchymosis and signs of infection, remembering that recognition of shock is difficult in children. Recently, the Health Authority has recommended to administer a third generation cephalosporin promptly (before biological investigations) for any child with signs of infection and a necrotic or ecchymotic purpura (> 3 mm of diameter), and then to refer the patient to the hospital. By grouping the patients from 7 studies, it can be observed that preadmission antibiotic administration has a protective effect on mortality (odds ratio: 0.36; 95% confidence interval: 0.23-0.56); a negative effect was observed in only one of these series. Children with purpura fulminans should be referred to a paediatric intensive care unit. Management includes antibiotics, steroids, fluid resuscitation and catecholamines (be aware of hypoglycaemia, particularly in infants, and hypocalcaemia). Treatment of cutaneous necrosis and distal ischemia is difficult and still controversial: antithrombin, protein C, tissue plasminogen activator and vasodilator infusion have no proven efficacy. Cases must be rapidly notified to the Public Health Service who will institute chemoprophylaxis for close contacts. Given the predominance of serogroup B in France, we hope that an efficient vaccine will soon become available.

Mechanical ventilatory support in infants with respiratory syncytial virus infection

OBJECTIVE: To present a review of current knowledge of the use of mechanical ventilatory support in the management of infants with respiratory failure secondary to infection with respiratory syncytial virus (RSV). DATA SOURCES: MEDLINE and manual search for case reports and clinical trials that address management strategies for respiratory support of infants with RSV infection. Data Extraction and Synthesis: Critical appraisal of reported epidemiologic and clinical data regarding risk factors, pathophysiology, and efficacy of respiratory therapy. There is an increasing number of hospital admissions for RSV infection with a variable proportion of infants who need mechanical ventilatory support. The mortality rate is estimated to be <1% in infants without preexisting respiratory or cardiac disorders vs. <5% in those with preexisting respiratory or cardiac disorders. Optimal ventilator settings need to be refined according to the dominant obstructive or restrictive pattern with the aim to avoid barovolutrauma. The role of noninvasive ventilation and additional therapies (heliox, beta(2) agonists, surfactant) is not conclusively established. The indications for high-frequency oscillatory ventilation with the possible adjunction of inhaled nitric oxide deserve further study. Extracorporeal membrane oxygenation plays a minor role in severe cases that are refractory to conventional treatment. CONCLUSIONS: Conventional ventilation strategies are usually adequate for treating infants with severe RSV infection. Particular attention must be paid to the dominant pathophysiologic mechanism in a given condition. Prospective trials are needed to validate alternative therapeutic options and to improve the outcome of the rare but most severe cases that are difficult to control.

Ventilator-induced overdistension in children: dynamic versus low-flow inflation volume-pressure curves

We applied to 20 paralyzed ventilated children (0.15 to 14.3 yr, six with acute respiratory distress syndrome [ARDS]) the low-flow inflation (LFI) technique providing quasi-static volume-pressure (V-P) curves and compared the assessment of overdistension (OD) on dynamic and LFI (reference) inspiratory V-P curves. Dynamic curves were obtained at the airway opening during regular constant flow ventilation (Servo 300). Then LFI curves were obtained. Two analyses were performed: First, the nonlinear coefficient c of a second order polynomial equation (SOPE) fitted to dynamic data obtained during constant flow was compared with the c of SOPE fitted to LFI curve (within tidal volume [VT]). Second, the dynamic C20/C (ratio of compliance of the last 20% of the curve (C20) to total compliance [C]) was compared with the determination of the upper inflection point (UIP) on the LFI curve. OD was defined as a negative value of c, a C20/C < 0.80, an UIP included within the VT range for that child during regular ventilation. Using LFI V-P curves as reference, SOPE offered a better detection of OD than dynamic C20/C or the determination of the UIP by graphical means. Indeed the first analysis showed a substantial agreement (kappa 0.75) between dynamic c and LFI c detection of OD whereas the second analysis showed a poor agreement (kappa 0.22) between C20/ C and LFI detection of the UIP. In conclusion, quasi-static V-P curves can easily be obtained in children with the LFI technique. SOPE offers a good detection of OD on dynamic and LFI V-P curves but the C20/C index seems to be an inadequate measure of OD.

[Upper airway obstruction (foreign bodies excluded)]

Upper airway obstruction is a frequent cause of admission to the emergency department and the intensive care unit. Symptoms are mainly represented by dyspnea and stridor. Severity must be rapidly assessed to allow adapted treatment and avoid cardiac arrest and hypoxic encephalopathy. The possible etiologies are numerous, with acquired and congenital ones, but the majority is represented by laryngitis, lymphoid hypertrophy and laryngotracheomalacia. In case of respiratory failure, treatment must first establish airway patency with bag and mask ventilation, and then intubation. If vital prognosis is not threatened, biologic, radiologic or endoscopic examination can be performed to identify the cause of the obstruction and treat it.