Elevated β-lactam concentrations associated with neurological deterioration in ICU septic patients

BACKGROUND

Although β-lactams are considered to have a safe therapeutic profile, neurotoxicity has been reported. The aim of this study was to assess the association between β-lactam concentrations and neurological alterations in septic ICU patients.

METHODS

Retrospective study on all ICU patients who were treated with meropenem (MEM), piperacillin-tazobactam (TZP) or ceftazidime/cefepime (CEF) and in whom at least one β-lactam trough concentration (C min) was determined. Drug levels were measured using high-performance liquid chromatography; C min was normalized to the clinical breakpoint of Pseudomonas aeruginosa (as determined by EUCAST) for each drug (C min/MIC). Changes in neurological status were evaluated using changes in the neurological sequential organ failure assessment score (ΔnSOFA) using the formula: ΔnSOFA = nSOFA(day of TDM) - nSOFA(ICU admission). Worsening neurological status (NWS) was defined as a ΔnSOFA ≥ 1 for an nSOFA on admission of 0-2.

RESULTS

We collected 262 C min in 199 patients (130 MEM, 85 TZP, 47 CEF). Median APACHE II score and GCS on admission were 17 and 15, respectively. Overall ICU mortality was 27 %. There were no differences in the occurrence of NWS between antibiotics (39% for MEM, 32% for TZP and 35% for CEF). The occurrence of NWS increased with increasing C min/MIC ranges (P = 0.008); this correlation was found for TZP (P = 0.05) and MEM (P = 0.01), but not for CEF. C min/MIC was an independent predictive factor for NWS (OR 1.12 [1.04-1.20]).

CONCLUSION

We found a correlation between high β-lactam trough concentrations and increased occurrence of neurological deterioration in septic ICU patients. Although our data cannot determine causality, monitoring of β-lactam levels should be considered when deterioration of neurological status occurs during critical illness.

[Recurrent episodes of brushite nephrolithiasis revealing primary hyperparathyroidism]

INTRODUCTION

Nephrolithiasis is a frequent disease observed in 1 to 20 % of the general population. This disease predominates in male patients (2:1) and is characterized by a high rate of recurrences (about 50 %).

CASE REPORT

We report the case of a 45-year old male patient who experienced during about ten years recurrent bilateral renal colic episodes due to brushite lithiasis. These stones were treated with multiple extracorporeal shock wave lithotripsy sessions. A pyeloureteral junction syndrome predisposing to bulky stones formation has been put in evidence and required a pyeloplasty. After more than ten years of disease activity, a biochemical screening diagnosed primary hyperparathyroidism (PHPT). Radiological assessment identified a parathyroid gland adenoma. Successful surgical removal of this lesion was followed by resolution of the symptomatic kidney stones formation.

DISCUSSION

PHPT is associated with kidney stones in about 20 % of the patients. Hypercalciuria is the main risk factor of stones formation but other predisposing factors are also probably involved. Patients carrying a polymorphism located in the coding sequence of the calcium-sensing receptor gene or in the regulatory region of this gene seem to experience an increased occurrence of urinary lithiasis.

CONCLUSION

The present case stresses the importance of a metabolic assessment in all patients with recurrent nephrolithiasis, especially in case of bilateral episodes.

Written production in a case of locked-in syndrome with bilateral corticopontic degeneration

Patients in locked-in syndrome show normal or near normal mental abilities that contrast with the limited motor capacity that hinders voluntary communication. However, eye movements and blinking are usually preserved and can be used to establish a communication system. We report an exceptional case of locked-in syndrome. The aetiology was basilar thrombosis consecutive to a cervical manipulation. In addition, brain MRI performed 23 years later showed a ventral pontine stroke with bilateral corticopontic degeneration. In this study the patient was able to produce written output using a chin-controlled Morse system decoded by a computer. A detailed linguistic analysis of text written over 20 years by the patient was carried out. The data demonstrate that improvements in language performance can be observed even in patients with brain lesions in areas associated with high-level cognitive processes. The data show a decrease of typing, grammatical and lexical errors over time, use of less frequent words, and an increase of more complex linguistic structures. This paper adds to previous findings confirming the value of daily practice and rehabilitation to enhance quality of life in this group of patients.

[Contribution of clinical biology in the etiological exploration and follow-up of urolithiasis]

Urolithiasis is a frequent pathology with a constantly increasing prevalence in industrial countries. The relapse frequency is around 50 % with a risk of complications. The laboratory input is essential in the determination of the etiology and in the therapeutic monitoring. The morphoconstitutional analysis of the stone is the most important element. It comprises the examination of the stone with binocular loupes and the simultaneous analysis of its crystalline composition. This can be done by different techniques but infrared spectrophotometry is the most powerful. The chemical analysis should be definitely proscribed. The analysis of crystalluria includes the search, the identification and the counting of crystals in fresh morning urines. It is useful for the diagnosis and for the patient follow-up. Finally, the biochemical analyses in urine and serum, in first line or on the basis of the stone composition, are an important part of the etiological exploration and therapeutic monitoring.

Lesions of the ovary with T1-hypersignal

Pelvic magnetic resonance imaging (MRI) has been used successfully to diagnose ovarian masses that cannot be adequately evaluated using pelvic ultrasound. T1 hyperintensity is a common finding in an ovarian mass and has important diagnostic implications. The aims of this review are to list the substances that may produce high signal intensity on T1-weighted MRI, to explain the physical basis for causes of the high T1 signal intensity, and to describe common and uncommon T1 hyperintense ovarian lesions. The morphological findings, the imaging features of the additional sequences, and clinical variables can help in the differential diagnosis, and in some cases, enable a specific diagnosis, leading to appropriate management of the patient.

β-lactam antibiotic concentrations during continuous renal replacement therapy

Introduction

The use of standard doses of β-lactam antibiotics during continuous renal replacement therapy (CRRT) may result in inadequate serum concentrations. The aim of this study was to evaluate the adequacy of unadjusted drug regimens (i.e., similar to those used in patients with normal renal function) in patients treated with CRRT and the influence of CRRT intensity on drug clearance.

Methods

We reviewed data from 50 consecutive adult patients admitted to our Department of Intensive Care in whom routine therapeutic drug monitoring (TDM) of broad-spectrum β-lactam antibiotics (ceftazidime or cefepime, CEF; piperacillin/tazobactam; TZP; meropenem, MEM) was performed using unadjusted β-lactam antibiotics regimens (CEF = 2 g q8h; TZP = 4 g q6h; MEM = 1 g q8h). Serum drug concentrations were measured twice during the elimination phase by high-performance liquid chromatography (HPLC-UV). We considered therapy was adequate when serum drug concentrations were between 4 and 8 times the minimal inhibitory concentration (MIC) of Pseudomonas aeruginosa during optimal periods of time for each drug (≥70% for CEF; ≥ 50% for TZP; ≥ 40% for MEM). Therapy was considered as early (ET) or late (LT) phase if TDM was performed within 48 hours of antibiotic initiation or later on, respectively.

Results

We collected 73 serum samples from 50 patients (age 58 ± 13 years; Acute Physiology and Chronic Health Evaluation II (APACHE II) score on admission 21 (17–25)), 35 during ET and 38 during LT. Drug concentrations were above 4 times the MIC in 63 (90%), but above 8 times the MIC in 39 (53%) samples. The proportions of patients with adequate drug concentrations during ET and LT were quite similar. We found a weak but significant correlation between β-lactam antibiotics clearance and CRRT intensity.

Conclusions

In septic patients undergoing CRRT, doses of β-lactam antibiotics similar to those given to patients with normal renal function achieved drug levels above the target threshold in 90% of samples. Nevertheless, 53% of samples were associated with very high drug levels and daily drug regimens may need to be adapted accordingly.

Can changes in renal function predict variations in β-lactam concentrations in septic patients?

This study investigated whether variations in creatinine clearance (CLCr) are correlated with changes in β-lactam concentrations or pharmacokinetics in septic patients. Data for 56 adult patients admitted to the ICU in whom routine therapeutic drug monitoring (TDM) of broad-spectrum β-lactams (ceftazidime, cefepime, piperacillin or meropenem) was performed were reviewed. Patients were included if they had at least two TDM during their ICU stay for the same antibiotic and were not concomitantly treated with any extracorporeal replacement therapy. Serum drug concentrations were measured by HPLC-UV. Antibiotic pharmacokinetics were calculated using a one-compartment model and the percentage of time spent above four times the MIC (%T>4×MIC) for Pseudomonas aeruginosa and the antibiotic clearance (ATB-CL) were obtained. CLCr was measured on the same day as the TDM using 24-h urine collection. The %T>4×MIC and ATB-CL were significantly correlated with CLCr at the first (r=-0.41, P=0.002; r=0.56, P<0.001, respectively) and second (r=-0.61, P<0.001; r=0.63, P<0.001, respectively) TDM. However, changes in ATB-CL were only weakly correlated with changes in CLCr (r=0.34, P=0.01). The proportion of patients with insufficient β-lactam concentrations at the first and second TDM were 39% and 30%, respectively, and increased proportionally to CLCr. Although CLCr was significantly correlated with concentrations and clearance of broad-spectrum β-lactams, changes in CLCr did not reliably predict variations in drug pharmacokinetics/pharmacodynamics. Routine TDM should be considered to adapt β-lactam doses in this setting.

[Giant ameloblastoma of the mandible]

INTRODUCTION

Giant ameloblastomas are more common in developing countries. They raise a serious problem of management. We present the case of one of the largest ameloblastoma ever reported.

CASE REPORT

A 48-year-old Congolese female patient was referred for mandibular swelling having begun 23 years before and now inducing severe functional disorders. A cephalic CT scan revealed a multicystic mass, 30×18×10cm in size, with a typical "soap bubble" presentation, and with thinned and inflated cortical bone. The treatment was sub-total segmental mandibulectomy with immediate reconstruction using a fibular free flap, modeled on the sampling site by four ostectomies. The pathological examination confirmed the diagnosis of a benign follicular and plexiform ameloblastoma. The excess of soft tissue was treated with a right commissuroplasty on the 15th postoperative day. There was no complication.

DISCUSSION

Radical treatment followed by immediate reconstruction using a free flap is the treatment of choice for giant mandibular ameloblastomas, when considering immediate functional and esthetic benefits. This is a prime concern for patients with a difficult access to health care and for whom long-term follow-up is not feasible.

Time course of iron metabolism in critically ill patients

BACKGROUND

Altered iron metabolism plays a central role in the development of anaemia in critically ill patients but the time course of iron status in septic and non-septic critically ill patients has not been well defined.

METHODS

Prospective study in a 34-bed medico-surgical ICU. The complete blood count, iron, ferritin, transferrin, and transferrin receptor concentrations, transferrin saturation and C-reactive protein (CRP) concentrations were measured on days 1, 3 and 5 of the ICU stay in 95 consecutive ICU patients (33 with sepsis and 62 without).

RESULTS

Despite an identical complete blood count on day 1, septic patients had significantly lower iron concentrations (21 [13-34] vs 50[28-75] microg/dL, p<0.001), transferrin concentrations (169[121-215] vs 214[173-247] mg/dL; p=0.003), and transferrin saturation (11[7-15] vs 19[11-25]%; p= 0.004), and higher ferritin concentrations (432[184-773] vs 204[78-354] ng/mL; p=0.002) than non-septic patients. These alterations were associated with a lower reticulocyte count (42[29-61] vs 58[48-77] x 10(3)/mm3; p=0.028). On day 1, CRP concentrations, which were higher in septic than in non-septic patients (20.0[13.5-27.5] vs 2.3[0.7-5.9] mg/dL; p<0.001), were directly correlated with ferritin concentrations (rho=0.55, p<0.001) and inversely correlated with transferrin concentrations (rho=-0.49, p=0.0001) and transferrin saturation (rho=-0.49, p=0.0001). After 3 days, iron and transferrin concentrations were identical in septic and non-septic patients. Iron metabolism remained altered in both populations until the 5th day.

CONCLUSIONS

Iron status is rapidly altered in critically ill patients, especially in septic patients. These alterations persist during the course of the disease and are associated with decreased erythropoiesis.

Reliability of longitudinal brain volume loss measurements between 2 sites in patients with multiple sclerosis: comparison of 7 quantification techniques

BACKGROUND AND PURPOSE

Brain volume loss is currently a MR imaging marker of neurodegeneration in MS. Available quantification algorithms perform either direct (segmentation-based techniques) or indirect (registration-based techniques) measurements. Because there is no reference standard technique, the assessment of their accuracy and reliability remains a difficult goal. Therefore, the purpose of this work was to assess the robustness of 7 different postprocessing algorithms applied to images acquired from different MR imaging systems.

MATERIALS AND METHODS

Nine patients with MS were followed longitudinally over 1 year (3 time points) on two 1.5T MR imaging systems. Brain volume change measures were assessed using 7 segmentation algorithms: a segmentation-classification algorithm, FreeSurfer, BBSI, KN-BSI, SIENA, SIENAX, and JI algorithm.

RESULTS

Intersite variability showed that segmentation-based techniques and SIENAX provided large and heterogeneous values of brain volume changes. A Bland-Altman analysis showed a mean difference of 1.8%, 0.07%, and 0.79% between the 2 sites, and a wide length agreement interval of 11.66%, 7.92%, and 11.94% for the segmentation-classification algorithm, FreeSurfer, and SIENAX, respectively. In contrast, registration-based algorithms showed better reproducibility, with a low mean difference of 0.45% for BBSI, KN-BSI and JI, and a mean length agreement interval of 1.55%. If SIENA obtained a lower mean difference of 0.12%, its agreement interval of 3.29% was wider.

CONCLUSIONS

If brain atrophy estimation remains an open issue, future investigations of the accuracy and reliability of the brain volume quantification algorithms are needed to measure the slow and small brain volume changes occurring in MS.