[Prescription of methylphenidate for children: importance of recommendations to limit misuse]

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder appearing during childhood. Multimodal strategies have been developed to treat this disorder, some of them including medication. To this day in France, prescriptions are mainly based on methylphenidate. Ever since this drug was marketed in France in 1995, it has been subject to enhanced monitoring, mainly because of the risk of dependence, abuse, and misuse. The present study aims at assessing (1) whether the recommendations on methylphenidate use for children are being respected, (2) the extent of problematic use of methylphenidate, and (3) the impact of said recommendations being respected on the development of problematic consumption. We studied patients who were treated with methylphenidate in an academic child psychiatry department. We specifically developed a semistructured interview grid for this study. Both parents and children were interviewed. In almost three out of four cases, at least one recommendation had not been followed (52% of patients did not follow the recommendation of stopping use during weekends and holidays). We found an average of 1.6 (range, 0-5) recommendations that were not respected. In almost two out of three cases, the consumption of methylphenidate was problematic; for 40% of children, this meant the search for at least one effect other than the expected therapeutic effects, such as an intellectual, creative, or athletic boosting effect. Approximately one-third of parents also sought an effect other than therapeutic for their child. Conversely, if all of the prescription recommendations were followed, less problematic consumption was observed. Methylphenidate-based treatments must therefore be implemented after a specialist has evaluated the patient and be prescribed following the recommendations. In this context, the treatment's benefits are undeniable.

Mechanical ventilation and clinical practice heterogeneity in intensive care units: a multicenter case-vignette study

BACKGROUND

Observational studies on mechanical ventilation (MV) show practice variations across ICUs. We sought to determine, with a case-vignette study, the heterogeneity of processes of care in ICUs focusing on mechanical ventilation procedures, and whether organizational patterns or physician characteristics influence practice variations.

METHODS

We conducted a cross-sectional multicenter study using the case-vignette methodology. Descriptive analyses were calculated for each organizational pattern and respondent characteristics. An Index of Qualitative Variation (IQV, from 0, no heterogeneity, to a maximum of 1) was calculated.

RESULTS

Forty ICUs from France (N = 33) and Switzerland (N = 7) participated; 396 physicians answered our case-vignettes. There was major heterogeneity of management processes related to MV within and across centers (mean IQV per center 0.51, SD 0.09). We observed the lowest variability (mean IQV per question < 0.4) for questions related to intubation procedure, ventilation of acute respiratory distress syndrome and the use of the semirecumbent position. We observed a high variability (mean IQV per question > 0.6) for questions related to management of endotracheal tube or suctioning, management of sedation and analgesia, and respect of autonomy. Heterogeneity was independent of respondent characteristics and of the presence of written procedures. There was a correlation between the processes associated with the highest variability (mean IQV per question > 0.6) and the annual volume of ICU admission (r = 0.32 (0.01 to 0.58)) and MV (r = 0.38 (0.07 to 0.63)). Within ICUs there was a large heterogeneity regarding knowledge of a local written procedure.

CONCLUSIONS

Large clinical practice variations were found among ICUs. High volume centers were more likely to have heterogeneous practices. The presence of a local written procedure or respondent characteristics did not influence practice variation.

Automated detection of patient-ventilator asynchrony: new tool or new toy?

Although severe patient-ventilator asynchrony is frequent during invasive and non-invasive mechanical ventilation, diagnosing such asynchronies usually requires the presence at the bedside of an experienced clinician to assess the tracings displayed on the ventilator screen, thus explaining why evaluating patient-ventilator interaction remains a challenge in daily clinical practice. In the previous issue of Critical Care, Sinderby and colleagues present a new automated method to detect, quantify, and display patient-ventilator interaction. In this validation study, the automatic method is as efficient as experts in mechanical ventilation. This promising system could help clinicians extend their knowledge about patient-ventilator interaction and further improve assisted mechanical ventilation.

Melanoma and rituximab: an incidental association?

Rituximab is an anti-CD20 monoclonal antibody increasingly used in haematology and rheumatology, but also in internal medicine and dermatology. It has a good tolerance profile without known increased risk of cancer. We report a case of nodular melanoma with a 4.8 mm Breslow thickness that appeared after 2 years of rituximab in a 45-year-old patient with non-Hodgkin lymphoma. Fifteen additional rituximab-associated melanoma cases in 13 patients have been identified in the literature and in the EudraVigilance database. These patients were treated for various indications and had melanomas, often aggressive, initially diagnosed at a metastatic stage in 31% of cases. Our work raises the question of rituximab accountability in melanoma onset in these immunosuppressed patients. A dermatological monitoring seems necessary in patients treated with rituximab, especially in case of risk factors for melanoma. In case of individual melanoma history, the benefit/risk ratio of initiating rituximab therapy should be carefully assessed.

Pharmacokinetics of ertapenem in burns patients

The aims of this study were to evaluate pharmacokinetic (PK) parameters of total and unbound ertapenem (ERT) in burns patients and to identify which covariates influence these PK parameters. ERT plasma concentrations were measured in burns patients (n = 8) who received a 0.5-h infusion of ERT (1000 mg) every 24 h. PK parameters were estimated by a non-compartmental approach and the influence of covariates was estimated by multivariate analysis using a population approach. Clearance (CL) and the volume of distribution (V) of total ERT were lower than the results for unbound ERT [CL, 22.2 ± 5.6 mL/min vs. 279.4 ± 208.2 mL/min; V, 9.7 ± 1.4L vs. 120.6 ± 130.6L (mean ± standard deviation)]. Creatinine clearance (CL(Cr)) and the burned surface area (BSA) were the covariates identified that significantly (P<0.01) affected the pharmacokinetics of total ERT [CL (L/h)=0.373 +{0.00666 x CL(Cr) (mL/min)}] and unbound ERT [peripheral volume of distribution (L) = 3.05 + {0.959 x BSA (% of the total body surface)}], respectively. The influences of albuminaemia, glomerular filtration and burn wound on ERT pharmacokinetics are proposed to explain these results. These first results support that the ERT plasma concentration should be closely monitored particularly for patients with high values of BSA and/or CL(Cr) to avoid suboptimal exposure.

Patient-ventilator asynchrony during noninvasive ventilation: a bench and clinical study

BACKGROUND

Different kinds of ventilators are available to perform noninvasive ventilation (NIV) in ICUs. Which type allows the best patient-ventilator synchrony is unknown. The objective was to compare patient-ventilator synchrony during NIV between ICU, transport—both with and without the NIV algorithm engaged—and dedicated NIV ventilators.

METHODS

First, a bench model simulating spontaneous breathing efforts was used to assess the respective impact of inspiratory and expiratory leaks on cycling and triggering functions in 19 ventilators. Second, a clinical study evaluated the incidence of patient-ventilator asynchronies in 15 patients during three randomized, consecutive, 20-min periods of NIV using an ICU ventilator with and without its NIV algorithm engaged and a dedicated NIV ventilator. Patient-ventilator asynchrony was assessed using flow, airway pressure, and respiratory muscles surface electromyogram recordings.

RESULTS

On the bench, frequent auto-triggering and delayed cycling occurred in the presence of leaks using ICU and transport ventilators. NIV algorithms unevenly minimized these asynchronies, whereas no asynchrony was observed with the dedicated NIV ventilators in all except one. These results were reproduced during the clinical study: The asynchrony index was significantly lower with a dedicated NIV ventilator than with ICU ventilators without or with their NIV algorithm engaged (0.5% [0.4%-1.2%] vs 3.7% [1.4%-10.3%] and 2.0% [1.5%-6.6%], P < .01), especially because of less auto-triggering.

CONCLUSIONS

Dedicated NIV ventilators allow better patient-ventilator synchrony than ICU and transport ventilators, even with their NIV algorithm. However, the NIV algorithm improves, at least slightly and with a wide variation among ventilators, triggering and/or cycling off synchronization.

Neurally adjusted ventilatory assist (NAVA) improves patient-ventilator interaction during non-invasive ventilation delivered by face mask

PURPOSE

To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation with an oronasal face mask.

METHODS

In this prospective interventional study we compared patient-ventilator synchrony between PS (with ventilator settings determined by the clinician) and NAVA (with the level set so as to obtain the same maximal airway pressure as in PS). Two 20-min recordings of airway pressure, flow and electrical activity of the diaphragm during PS and NAVA were acquired in a randomized order. Trigger delay (T(d)), the patient's neural inspiratory time (T(in)), ventilator pressurization duration (T(iv)), inspiratory time in excess (T(iex)), number of asynchrony events per minute and asynchrony index (AI) were determined.

RESULTS

The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T(d) was reduced with NAVA: median 35 ms (IQR 31-53 ms) versus 181 ms (122-208 ms); p = 0.0002. NAVA reduced both premature and delayed cyclings in the majority of patients, but not the median T(iex) value. The total number of asynchrony events tended to be reduced with NAVA: 1.0 events/min (0.5-3.1 events/min) versus 4.4 events/min (0.9-12.1 events/min); p = 0.08. AI was lower with NAVA: 4.9 % (2.5-10.5 %) versus 15.8 % (5.5-49.6 %); p = 0.03. During NAVA, there were no ineffective efforts, or late or premature cyclings. PaO(2) and PaCO(2) were not different between ventilatory modes.

CONCLUSION

Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T(d) and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent.

Clinical review: Update on neurally adjusted ventilatory assist--report of a round-table conference

Conventional mechanical ventilators rely on pneumatic pressure and flow sensors and controllers to detect breaths. New modes of mechanical ventilation have been developed to better match the assistance delivered by the ventilator to the patient's needs. Among these modes, neurally adjusted ventilatory assist (NAVA) delivers a pressure that is directly proportional to the integral of the electrical activity of the diaphragm recorded continuously through an esophageal probe. In clinical settings, NAVA has been chiefly compared with pressure-support ventilation, one of the most popular modes used during the weaning phase, which delivers a constant pressure from breath to breath. Comparisons with proportional-assist ventilation, which has numerous similarities, are lacking. Because of the constant level of assistance, pressure-support ventilation reduces the natural variability of the breathing pattern and can be associated with asynchrony and/or overinflation. The ability of NAVA to circumvent these limitations has been addressed in clinical studies and is discussed in this report. Although the underlying concept is fascinating, several important questions regarding the clinical applications of NAVA remain unanswered. Among these questions, determining the optimal NAVA settings according to the patient's ventilatory needs and/or acceptable level of work of breathing is a key issue. In this report, based on an investigator-initiated round table, we review the most recent literature on this topic and discuss the theoretical advantages and disadvantages of NAVA compared with other modes, as well as the risks and limitations of NAVA.

Perception of non-invasive ventilation in adult Swiss intensive care units

The real utilisation scenario of non-invasive ventilation (NIV) in Swiss ICUs has never been reported. Using a survey methodology, we developed a questionnaire sent to the directors of the 79 adult ICUs to identify the perceived pattern of NIV utilisation. We obtained a response rate of 62%. The overall utilisation rate for NIV was 26% of all mechanical ventilations, but we found significant differences in the utilisation rates among different linguistic areas, ranging from 20% in the German part to 48% in the French part (p <0.01). NIV was mainly indicated for the acute exacerbations of COPD (AeCOPD), acute cardiogenic pulmonary edema (ACPE) and acute respiratory failure (ARF) in selected do-not-intubate patients. In ACPE, CPAP was much less used than bi-level ventilation and was still applied in AeCOPD. The first line interface was a facial mask (81%) and the preferred type of ventilator was an ICU machine with an NIV module (69%). The perceived use of NIV is generally high in Switzerland, but regional variations are remarkable. The indications of NIV use are in accordance with international guidelines. A high percentage of units consider selected do-not-intubate conditions as an important additional indication.

A statement on cefazolin immediate hypersensitivity: data from a large database, and focus on the cross-reactivities

BACKGROUND

More perioperative cefazolin use has resulted in an increased risk of cefazolin-associated reactions.

OBJECTIVE

The aim of this article is to study immediate reactions to cefazolin and attempt to determine possible allergic cross-reactivity with other ß-lactams using data from the Drug Allergy and Hypersensitivity Database (DAHD).

METHODS

All 25 cefazolin-associated reactions in the DAHD were reviewed. The cases identified were then investigated according to the European Network for Drug Allergy (ENDA) recommendations by skin testing and challenges.

RESULTS

A total of 10 individuals with proven IgE-mediated cefazolin hypersensitivity were identified between January 1999 and July 2009. All the index reactions were compatible with an acute IgE-mediated process, six with anaphylaxis, two with systemic allergic reactions without hypotension, and two with urticaria/angioedema. Cefazolin skin tests were positive in seven individuals and cefazolin challenges were positive in three more individuals. In the eight cefazolin allergic patients who had challenges with other ß-lactams, there was no positive reaction noted.

CONCLUSION AND CLINICAL RELEVANCE

In this cohort of patients with IgE-mediated reactions to cefazolin, a majority tolerated amoxicillin and several patients tolerated other cephalosporins. This implies that the R1 side-chain may play an essential role in IgE-mediated reactions to cefazolin. No clear rule to predict cross-reactivity with other ß-lactams could be determined. More research on IgE-mediated hypersensitivity to cefazolin and other cephalosporins is needed.