Impact on the medical decision-making process of multiplex PCR assay for respiratory pathogens.

The objective of this study was to determine how clinicians make use of the modern multiplex PCR assays (MPAs) to manage patients hospitalized for community-acquired pneumonia (CAP). We studied the use of MPAs in 1648 patients hospitalized for CAP over a 3-year period at the moment of the setup of the new PCR assay. We observed that the use of MPAs for the identification of multiple respiratory pathogens marks a radical change in the investigation of CAP etiology. Surprisingly, the contribution of MPAs to the medical decision-making process varies drastically according to the units of care.

Pharmacokinetics of high-dose nebulized amikacin in ventilated critically ill patients.

BACKGROUND: Antibiotic nebulization theoretically allows the delivery of high doses to the lungs together with limited systemic exposure and toxicity. This study aimed to describe amikacin pharmacokinetics, and especially its absorption, in patients treated with high-dose nebulized amikacin. PATIENTS AND METHODS: Twenty critically ill patients experiencing ventilator-associated pneumonia received a 20 mg/kg infusion of amikacin, followed by either three other infusions or three nebulizations of 60 mg/kg amikacin. An extensive sampling regimen allowed measurement of amikacin serum concentrations at 0.5, 1, 1.5, 2, 3, 4, 6, 10 and 24 h after each administration. Amikacin pharmacokinetics was studied by population compartmental modelling. RESULTS: Amikacin pharmacokinetics was best described using a two-compartment structural model with first-order distribution and elimination, in which lung absorption was described using a transit model. Estimated means (interindividual variability) of the main parameters were: bioavailability F = 2.65% (22.1%); transit compartments n = 1.58 (fixed); transit constant ktr = 1.38 h-1 (33.4%); central volume Vc = 10.2 L (10.5%); and elimination constant k10 = 0.488 h-1 (35.8%). The addition of interoccasion variability on F (44.0%) and k10 (41.7%) allowed the description of intraindividual variability of bioavailability and elimination. Amikacin clearance was positively correlated with baseline creatinine clearance. CONCLUSIONS: Our pharmacokinetic model provided an accurate description of amikacin concentrations following nebulization. There was wide interindividual and interoccasion variability in the absorption and elimination of amikacin. Nevertheless, systemic exposure after nebulization was always much lower than after infusion, an observation suggesting that nebulized high doses are safe in this regard and may be used to treat ventilator-associated pneumonia.

Predicting arterial blood gas and lactate from central venous blood analysis in critically ill patients: a multicentre, prospective, diagnostic accuracy study.

BACKGROUND: The estimation of arterial blood gas and lactate from central venous blood analysis and pulse oximetry [Formula: see text] readings has not yet been extensively validated. METHODS: In this multicentre, prospective study performed in 590 patients with acute circulatory failure, we measured blood gases and lactate in simultaneous central venous and arterial blood samples at 6 h intervals during the first 24 h after insertion of central venous and arterial catheters. The study population was randomly divided in a 2:1 ratio into model derivation and validation sets. We derived predictive models of arterial pH, carbon dioxide partial pressure, oxygen saturation, and lactate, using clinical characteristics, [Formula: see text], and central venous blood gas values as predictors, and then tested their performance in the validation set. RESULTS: In the validation set, the agreement intervals between predicted and actual values were -0.078/+0.084 units for arterial pH, -1.32/+1.36 kPa for arterial carbon dioxide partial pressure, -5.15/+4.47% for arterial oxygen saturation, and -1.07/+1.05 mmol litre(-1) for arterial lactate (i.e. around two times our predefined clinically tolerable intervals for all variables). This led to ∼5% (or less) of extreme-to-extreme misclassifications, thus giving our predictive models only marginal agreement. Thresholds of predicted variables (as determined from the derivation set) showed high predictive values (consistently >94%), to exclude abnormal arterial values in the validation set. CONCLUSIONS: Using clinical characteristics, [Formula: see text], and central venous blood analysis, we predicted arterial blood gas and lactate values with marginal accuracy in patients with circulatory failure. Further studies are required to establish whether the developed models can be used with acceptable safety.

Diagnosis of community-acquired acute respiratory illness: From conventional microbiological methods to molecular detection (multiplex).

Investigations of the etiologic agents of community-acquired acute respiratory illness may lead to better treatment decisions and patient outcomes. In a routine care setting, we assessed the diagnostic performance of a multiplex PCR assay with respect to conventional microbiological methods, in a continuous series of adult cases of community-acquired acute respiratory illness. We enrolled 279 adult patients hospitalised for community-acquired acute respiratory illness at Tours University Hospital during the winter of 2011-2012. Respiratory samples (mostly nasopharyngeal aspirates) were studied prospectively by indirect immunofluorescence assay and multiplex PCR, that enable detection of 8 viruses and 21 respiratory pathogens respectively. In total, 255 of the 279 (91.4%) samples had interpretable results by both methods. At least one respiratory pathogen was detected by multiplex PCR in 171 specimens (65%). Overall, 130 (76%) of the 171 positive samples were positive for only one respiratory pathogen, 37 (22%) samples were positive for two pathogens and four (2%) were positive for three pathogens. With indirect immunofluorescence assay, a respiratory virus was detected in 27 of the 255 (11%) specimens. Indirect immunofluorescence assay detected some of the influenza virus A (15/51, 29%) infections identified by multiplex PCR and some (7/15, 47%) human metapneumovirus and (5/12, 42%) respiratory syncytial virus infections, but it did not detect all the adenovirus infections. Thus, access to multiplex molecular assays improves the diagnostic spectrum and accuracy over conventional methods, increasing the frequency of identification of the respiratory pathogens involved in community-acquired acute respiratory illness.

Hashimoto's encephalopathy in the intensive care unit.

BACKGROUND: Since the first description of Hashimoto's Encephalitis (HE) in 1966 by Lord Brain, the number of reported cases has continued to increase. In addition, cases of status epilepticus have been reported, suggesting a role for intensive care unit (ICU) practitioners in taking care of patients with HE. METHODS: A retrospective cohort study in ICU patients with HE was performed at the University Hospital of Tours, France. RESULTS: Eight HE cases were admitted to the ICU between 1/1/2000 and 1/1/2012. Herein, we describe the characteristics of the patients, with an emphasis on ICU disease management and its outcome. CONCLUSION: ICU practitioners should be aware of this disease, since it can include life-threatening presentations.

[Cutaneous periarteritis nodosa: diagnostic and therapeutic aspects of 9 cases]. / Périartérite noueuse cutanée. Particularités diagnostiques et thérapeutiques de 9 cas.

BACKGROUND: Cutaneous periarteritis nodosa (PAN) is distinguished from systemic PAN by the lack of visceral involvement. The aim of this study was to describe the clinical presentation, laboratory findings, clinical course, and treatment in cutaneous PAN. PATIENTS AND METHODS: We retrospectively reviewed the files of patients hospitalized for vasculitis in our Dermatology unit where approximately 20 cases of vasculitis are seen each year. Inclusion criteria were skin signs suggestive of PAN and a histological image of leukocytoclastic vasculitis of an arteriole. RESULTS: Nine cases of cutaneous PAN were treated in our unit between 1976 and 1997. Follow-up ranged from 32 months to 22 years. No cases of systemic PAN had been diagnosed during this period. These 9 cases of cutaneous PAN all had the same clinical presentation: nodules on the lower limbs in all cases associated with nodules on the upper limbs in half of the cases. Neuropathy was found in 3 of the 9 cases. No systemic involvement was observed. The most frequently used treatment protocol was general corticosteroid therapy (0.5 mg/kg/d prednisone or prednisolone). Immunosuppressive drugs, colchicine, dapsone, non-steroidal anti-inflammatory drugs and intravenous immunoglobulins were also used with efficacy. DISCUSSION: Cutaneous PAN is a particular form of vasculitis associating skin signs with locoregional neuromuscular involvement. The differential diagnosis with other types of vasculitis is sometimes a difficult task. The clinical course is the fundamental diagnostic clue in cutaneous PAN. A benign course and the absence of visceral involvement allow initiating a symptomatic treatment such as colchicine. The development of neuromuscular signs may warrant the use of general corticosteroid therapy.

[Crossed spinach-latex allergy revealed by exercise-induced anaphylaxis]. / Allergie croisée épinard-latex révélée par une anaphylaxie induite par l'exercice.

Diagnosis of exercise-induced anaphylaxis is based on conjunction between a specific factor: a specific or nonspecific food allergy and exercise. The authors report observation of a patient who presented with exercise-induced anaphylaxis associated with food allergy to spinach, but also with a cross reaction with latex.

Airway obstruction by an aortic false aneurysm.

Aortic false aneurysms are rare complications of aortic valve replacement and cardiac surgical procedures in general. Aortic false aneurysms can also presents as a mediastinal mass. A false aneurysm etiology should always be considered in mediastinal mass exploration of patients with a cardiac surgery history. Although, a computed tomography (CT) scan can detect a mediastinal mass, it can equally misdiagnose an aneurysm in the absence of tumour contrast enhancement. We present the case of a 60-year-old woman who was hospitalized for a laryngeal dyspnea. She had undergone aortic valve replacement 3 years earlier and had no other relevant medical history. In the last 3 months, she presented a progressively worsening dyspnea and cough. A chest radiograph showed a large mass in the superior mediastinum. A contrast-enhanced CT-scan showed an anterior mediastinal mass (9 cm × 8 cm × 9 cm) not enhanced by contrast product, suggestive of a tissue density tumour. The mass was in fact an aortic false aneurysm where the communication with the aorta was too narrow to be filled by the contrast product in arterial phase imaging. The aneurysm was excised and successfully replaced with a prosthetic graft during deep hypothermic and circulatory arrest. In this case report, we discuss the unusual clinical presentation of this pseudoaneurysm and the absence of contrast enhancement during CT-scan, which could have lead to a catastrophic error.