Prospective pilot study for evaluation of high-flow oxygen therapy in dyspnoeic dogs: the HOT-DOG study

OBJECTIVES

To describe the use, effectiveness and tolerance of high-flow oxygen therapy in dyspnoeic dogs.

MATERIALS AND METHODS

Prospectively, dogs in acute respiratory distress admitted to an intensive care unit between January and May 2018 that failed to respond to nasal oxygen therapy and medical stabilisation after 30 minutes were transitioned to high-flow oxygen therapy. High-flow oxygen therapy, delivered an inspired oxygen fraction of 100% using an air/oxygen blender, active humidifier, single warmed tube and specific nasal cannula. Respiratory rate, pulse oximetry (SpO₂ ), heart rate and a tolerance score were assessed every 15 minutes from T₀ (under nasal oxygen) to 1 hour (T₆₀ ), and PaO₂ and PaCO₂ at T₀ and T₆₀ . Complications were recorded for each dog.

RESULTS

Eleven dogs were included. At T₆₀ , PaO₂ , flow rate and SpO₂ were significantly greater than at T₀ (171 ± 123 versus 73 ± 24 mmHg; P=0.015; 18 ±12 L/minute versus 3.2 ± 2.0 L/minute, P<0.01; 97.7 ±2.3% versus 91.6 ±7.2%, P=0.03, respectively). There was no significant difference in PaCO₂ , respiratory rate or heart rate between T₀ and T₆₀ . Tolerance was excellent, and there were no complications.

CLINICAL SIGNIFICANCE

High-flow oxygen therapy improves markers of oxygenation in dyspnoeic dogs and is an effective means to deliver oxygen with comfort and minimal complications.

[Evaluation of spinal anesthesia in urological outpatient surgery, comparison between two local anesthetics (Chloroprocaine/Bupivacaine)]

INTRODUCTION

Spinal anesthesia in outpatient urology is controversial (longer hospital stay, risk of urinary retention). The main goal was to evaluate outpatient spinal anesthesia and to compare 2 local anesthetics secondarily.

MATERIAL

Monocentric retrospective study including all patients undergoing surgery in urological ambulatory surgery under spinal anesthesia between December 2011 and May 2015, split into two groups according to the local anesthetic used: bupivacaine (BP) and chloroprocaine (CP). Quantitative variables were compared by Student's t-test, qualitative variables by χ² test.

RESULTS

Seventy-one (95%) out of the 75 patients included have been discharged the same day. Discharge was impossible in these cases: patient alone at home (1), bladder clot (1), JJ intolerance (1), delayed micturition (1). The mean duration of the procedure was 27±19min, the SSPI's was 55±31min, the stay's was 360±91min. A total of 45 patients (60%) received BP and 30 (40%) received CP. The mean residence time in SSPI was significantly reduced in the CP group (47±24min vs. 61±34min, P=0.04). One patient experienced urination delay in the BP group with no significant difference. No significant difference for the other criteria studied despite the mean age, which is higher in the CP group (P=0.02).

CONCLUSION

Spinal anesthesia is adapted to ambulatory urology, and does not increase the risk of urinary retention, especially with CP that would decrease the length of stay in SSPI compared to BP.

LEVEL OF EVIDENCE

4.

Comparison of piperacillin exposure in the lungs of critically ill patients and healthy volunteers

Background

Severe infections of the respiratory tracts of critically ill patients are common and associated with excess morbidity and mortality. Piperacillin is commonly used to treat pulmonary infections in critically ill patients. Adequate antibiotic concentration in the epithelial lining fluid (ELF) of the lung is essential for successful treatment of pulmonary infection.

Objectives

To compare piperacillin pharmacokinetics/pharmacodynamics in the serum and ELF of healthy volunteers and critically ill patients.

Methods

Piperacillin concentrations in the serum and ELF of healthy volunteers and critically ill patients were compared using population methodologies.

Results

Median piperacillin exposure was significantly higher in the serum and the ELF of critically ill patients compared with healthy volunteers. The IQR for serum piperacillin exposure in critically ill patients was six times greater than for healthy volunteers. The IQR for piperacillin exposure in the ELF of critically ill patients was four times greater than for healthy volunteers. The median pulmonary piperacillin penetration ratio was 0.31 in healthy volunteers and 0.54 in critically ill patients.

Conclusions

Greater variability in serum and ELF piperacillin concentrations is observed in critically ill patients compared with healthy adult subjects and must be considered in the development of dosage regimens. Pulmonary penetration of antimicrobial agents should be studied in critically ill patients, as well as healthy volunteers, during drug development to ensure appropriate dosing of patients with pneumonia.

Physiological Signal Processing for Individualized Anti-nociception Management During General Anesthesia: a Review

OBJECTIVE

The aim of this paper is to review existing technologies for the nociception / anti-nociception balance evaluation during surgery under general anesthesia.

METHODS

General anesthesia combines the use of analgesic, hypnotic and muscle-relaxant drugs in order to obtain a correct level of patient non-responsiveness during surgery. During the last decade, great efforts have been deployed in order to find adequate ways to measure how anesthetic drugs affect a patient's response to surgical nociception. Nowadays, though some monitoring devices allow obtaining information about hypnosis and muscle relaxation, no gold standard exists for the nociception / anti-nociception balance evaluation. Articles from the PubMed literature search engine were reviewed. As this paper focused on surgery under general anesthesia, articles about nociception monitoring on conscious patients, in post-anesthesia care unit or in intensive care unit were not considered.

RESULTS

In this article, we present a review of existing technologies for the nociception / anti-nociception balance evaluation, which is based in all cases on the analysis of the autonomous nervous system activity. Presented systems, based on sensors and physiological signals processing algorithms, allow studying the patients' reaction regarding anesthesia and surgery.

CONCLUSION

Some technological solutions for nociception / antinociception balance monitoring were described. Though presented devices could constitute efficient solutions for individualized anti-nociception management during general anesthesia, this review of current literature emphasizes the fact that the choice to use one or the other mainly relies on the clinical context and the general purpose of the monitoring.

The use of ultrasound in France: a point of view from experienced regional anesthesiologists

A cross-sectional survey study on French practice in ultrasound-guided regional anesthesia was carried out. A questionnaire (demographic data, assessment of the likely benefits of ultrasonography, and its use in daily practice: blocks and hygiene) was emailed to all members of the French-speaking association of anesthesiologists involved in regional anesthesia. The questionnaire was filled out and returned by 634 experienced anesthesiologists. An ultrasound machine was available in 94% of cases. Ultrasound-guided regional anesthesia has become the gold standard technique for three-quarters of responders. Axillary, interscalene, popliteal sciatic and femoral nerve blocks were performed by more than 90% of responders, most frequently under ultrasound supervision. Conversely, ultrasound guidance was rarely used for spinal or deep nerve blocks. A specific sterile sheath was used in only 43% of cases. The present study confirms that ultrasound guidance has gained in popularity for many superficial, but not deep, regional anesthesia procedures in France.

Prediction of hemodynamic reactivity using dynamic variations of Analgesia/Nociception Index (∆ANI)

The Analgesia/Nociception Index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anesthesia. We hypothesized that dynamic variations of ANI (∆ANI) would provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. One hundred and twenty-eight patients undergoing ear-nose-throat or lower limb orthopedic surgery were analyzed in this prospective observational study. The ANI, heart rate and systolic blood pressure were recorded before induction, at skin incision, during procedure and at emergence from general anesthesia. Changes in these variables were recorded after 1 min for ANI (ANI_1min) and 5 min for heart rate and systolic blood pressure. The dynamic variation of ANI at the different time points was defined as: ∆ANI = (ANI_1min - ANI)/([ANI + ANI_1min]/2). Receiver-operating characteristic (ROC) curves were built to evaluate the performance of ANI, ANI1 min and ∆ANI to predict hemodynamic reactivity (increase by more than 20 % in heart rate and/or systolic blood pressure within 5 min). For the prediction of hemodynamic reactivity, better performance was observed with ∆ANI (area under ROC curve (AUC ROC) = 0.90) in comparison to ANI (ROC AUC = 0.50) and ANI_1min (ROC AUC = 0.77). A ∆ANI threshold of -19 % predicts hemodynamic reactivity with 85 % [95 % CI 77-91] sensitivity and 85 % [95 % CI 81-89] specificity. Dynamic variations of ANI provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. These findings may be of interest for the individual adaptation of remifentanil doses guided by ∆ANI during general anesthesia, although this remains to be demonstrated.

Prediction of hemodynamic reactivity during total intravenous anesthesia for suspension laryngoscopy using Analgesia/Nociception Index (ANI): a prospective observational study

BACKGROUND

The Analgesia/Nociception Index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anesthesia. The principal objective of this study was to evaluate the performance of ANI to predict hemodynamic reactivity during suspension laryngoscopy. The secondary objectives were to investigate the performances of ANI and bispectral index (BIS) to assess sedation and of BIS to predict hemodynamic reactivity during the procedure.

METHODS

Fifty patients undergoing suspension laryngoscopy with total intravenous anesthesia using propofol and remifentanil were analysed in this prospective observational study. The ANI, BIS and Observer's Assessment of Alertness/Sedation (OAA/S) scale were measured at predefined time-points during the procedure. Receiver-operating characteristic (ROC) curves were built to evaluate the performance of ANI and BIS to predict hemodynamic reactivity (increase by more than 20% of heart rate and/or systolic blood pressure within 5 min) and assess sedation (OAA/S ≤ 2) during the procedure.

RESULTS

For the prediction of hemodynamic reactivity, better performance was observed with ANI in comparison to BIS (ROC curve AUC [95% CI] = 0.88 [0.83-0.92] vs. 0.73 [0.66-0.79], P < 0.05). The sensitivity and specificity of ANI ≤ 55 to predict hemodynamic reactivity within 5 min were 88% and 83%, respectively. For the assessment of sedation, a better performance was observed with BIS in comparison to ANI (ROC curve AUC [95% CI] = 0.91 [0.86-0.94] vs. 0.68 [0.61-0.74], respectively, P < 0.05).

CONCLUSION

ANI exhibits good performance for the prediction of hemodynamic reactivity and BIS exhibits good performance for the assessment of sedation during suspension laryngoscopy with propofol/remifentanil total intravenous anesthesia.

Prediction of immediate postoperative pain using the analgesia/nociception index: a prospective observational study

BACKGROUND

The analgesia/nociception index (ANI) is derived from heart rate variability, ranging from 0 (maximal nociception) to 100 (maximal analgesia), to reflect the analgesia/nociception balance during general anaesthesia. This should be correlated with immediate postoperative pain in the post-anaesthesia care unit (PACU). The aim of this study was to evaluate the performance of ANI measured at arousal from general anaesthesia to predict immediate postoperative pain on arrival in PACU.

METHODS

Two hundred patients undergoing ear, nose, and throat or lower limb orthopaedic surgery with general anaesthesia using an inhalational agent and remifentanil were included in this prospective observational study. The ANI was measured immediately before tracheal extubation and pain intensity was assessed within 10 min of arrival in PACU using a 0-10 numerical rating scale (NRS). The relationship between ANI and NRS was assessed using linear regression. A receiver-operating characteristic (ROC) curve was used to evaluate the performance of ANI to predict NRS>3.

RESULTS

A negative linear relationship was observed between ANI immediately before extubation and NRS on arrival in PACU. Using a threshold of <50, the sensitivity and specificity of ANI to discriminate between patients with NRS≤3 and NRS>3 were both 86% with 92% negative predictive value, corresponding to an area under the ROC curve of 0.89.

CONCLUSIONS

The measurement of ANI immediately before extubation after inhalation-remifentanil anaesthesia was significantly associated with pain intensity on arrival in PACU. The performance of ANI for the prediction of immediate postoperative pain is good and may assist physicians in optimizing acute pain management.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01796249.

Prospective observational study of the non-invasive assessment of immediate postoperative pain using the analgesia/nociception index (ANI)

BACKGROUND

The analgesia/nociception index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anaesthesia. The aim of this study was to evaluate the ANI in the assessment of immediate postoperative pain in adult patients undergoing general anaesthesia.

METHODS

Two-hundred patients undergoing scheduled surgery or endoscopy with general anaesthesia were included in this prospective observational study. Pain intensity was assessed using a 0-10 numerical rating scale (NRS) after arousal from general anaesthesia. Receiver-operating characteristic (ROC) curves were built to assess the performance of ANI to detect patients with NRS>3 and NRS ≥ 7 on arrival in the postoperative care unit.

RESULTS

A negative linear relationship was observed between ANI and NRS (ANI=-5.2 × NRS+77.9, r(2)=0.41, P<0.05). At the threshold of 57, the sensitivity and specificity of ANI to detect patients with NRS>3 were 78 and 80%, respectively, with a negative predictive value of 88%, corresponding to an area under the ROC curve (AUC) of 0.86. At the threshold of 48, the sensitivity and specificity of ANI to detect NRS ≥ 7 were 92 and 82%, respectively, with a negative predictive value of 99%, corresponding to a ROC curve AUC of 0.91.

CONCLUSIONS

A measurement of ANI during the immediate postoperative period is significantly correlated with pain intensity. The measurement of ANI appears to be a simple and non-invasive method to assess immediate postoperative analgesia.

Immediate allergic cross-reactivity to levobupivacaine and ropivacaine

Allergic reactions to amide local anaesthetic agents are rare. We report the case of a 74-year-old man who suffered anaphylaxis, presenting with cardiovascular collapse, immediately after receiving regional anaesthesia on two separate occasions, the first involving the use of levobupivacaine and the second using ropivacaine. Skin testing revealed positive reactions to both levobupivacaine and ropivacaine, and negative reactions to articaine and lidocaine. Severe allergic reactions can be caused by the amide local anaesthetic drugs, levobupivacaine and ropivacaine.

Pharmacokinetics of free ertapenem in critically ill septic patients: intermittent versus continuous infusion

BACKGROUND

The aim of this paper was to compare the pharmacokinetic and pharmacodynamic (PK/PD) parameters of continuous (CI) and intermittent infusion (ITI) of ertapenem into critically ill patients with severe abdominal infections.

METHODS

Twenty septic patients hospitalized in a university hospital intensive care unit were enrolled in the study. Half of the patients received ertapenem as an ITI 1 g bolus once daily, and the other half of the patients received the same dose via CI over 24 h following a 1-g loading dose. Blood was drawn 1, 12 and 24 h after terminating ITI or on days 2, 3 and 5 after starting CI for each patient. After centrifugation, the drawn blood was frozen at -80 °C until being examined by high-performance liquid-chromatography analysis.

RESULTS

Median serum-free ertapenem concentrations were as follows: ƒCmax = 98.9 mg/L and ƒCmin = 2.5 mg/L for ITI, and ƒCss=15.9 mg/L for CI. The ITI and CI median total clearance and volumes of distribution were 2.2 L/h vs. 2.5 L/h and 15.4 L vs. 21.0 L, respectively. The ertapenem MIC ranges were as follows: Escherichia coli (0.006 to 0.5 mg/L), Enterobacter cloacae (0.023 to 0.5 mg/L), Klebsiella oxytoca (0.023 to 0.5 mg/L), Staphylococcus aureus (0.38 to 3 mg/L), Streptococcus viridians (0.38 to 3 mg/L) and Enterococcus faecalis (0.38 to 3 mg/L). ITI and CI provided steady-state serum-free ertapenem concentrations constantly above the MIC for all bacteria.

CONCLUSION

Ertapenem exhibited satisfactory PK/PD parameters and achieved serum-free concentrations 100% of the time, above even the high MIC of extracellular pathogens normally encountered during severe abdominal infections. CI administration resulted in equally effective PK/PD parameters as ITI in normal weight, good renal-function patients.

Diffusion of ertapenem into bone and synovial tissues

OBJECTIVES

The degree of penetration of an antibiotic into the infected site is an important criterion for therapeutic success. Ertapenem is a new carbapenem, exhibiting activity against most Gram-positive and Gram-negative aerobic and anaerobic bacteria commonly recovered from community-acquired infections. However, no studies concerning its diffusion into bone and synovial tissue are available. Our objective was to quantify ertapenem bone and synovial tissue penetration and to compare our data with the MIC(90)s for causative pathogens.

PATIENTS AND METHODS

In an open-label study, 18 patients who were undergoing elective total hip replacement received a single, parenteral, 1 g dose of ertapenem. One serum, one cortical and cancellous bone and one synovial tissue sample was collected per patient a median [interquartile range (IQR)] of 1.6 (1.5-1.7), 12.4 (11.9-13.1) or 23.8 h (22.6-25.2) later and analysed by HPLC.

RESULTS

The median (IQR) serum concentrations of ertapenem were 70.1 (56.1-75.9), 10.0 (9.1-11.2) and 2.6 mg/L (2.3-3.0), respectively, at the different time points. The median (IQR) cancellous bone tissue concentrations were 13.2 (10.2-14.8), 1.9 (1.7-2.1) and 0.6 microg/g (0.4-0.6) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.19 (0.18-0.23). The median (IQR) cortical bone tissue concentrations were 8.0 (6.5-9.5), 1.3 (1.2-1.3) and 0.3 microg/g (0.3-0.4) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.13 (0.12-0.14). The median (IQR) synovial tissue concentrations were 26.2 microg/g (22.7-28.4), 4.0 mg/L (3.7-4.4) and 1.0 mg/L (0.9-1.2) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.41 (0.39-0.42).

CONCLUSIONS

The concentrations after an ertapenem 1 g dose achieved in cancellous and cortical bone tissue and in synovial tissue were greater than the MIC(90)s for most aerobic organisms for 24 h, and for 12 to 24 h for anaerobic bacteria in healthy volunteers undergoing total hip replacement.

Flow rate, syringe size and architecture are critical to start-up performance of syringe pumps

BACKGROUND AND OBJECTIVES

Levobupivacaine in combination with sufentanil may be used for labour or postoperative regional analgesia. The risk of bacterial growth within these contained solutions for several hours at room temperature is unknown. We investigated the in vitro antimicrobial effect of levobupivacaine and sufentanil against common micro-organisms encountered during regional anaesthesia.

METHODS

Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated for 1, 3, 6 and 24 h at 25 degrees C, with saline (as control), sufentanil 0.5 or 0.75 microg mL-1, levobupivacaine hydrochloride 5.6 mg mL-1 and concentrations of 1.4, 2.8 and 5 mg mL-1 of levobupivacaine hydrochloride with sufentanil 0.5 microg mL-1. Colony counts were compared after 24 h incubation at 37 degrees C.

RESULTS

No bacterial growth was observed on any bacterial strain for any solution tested throughout the experiment.

CONCLUSIONS

Our results suggest that solutions of levobupivacaine combined with sufentanil may be used for 24 h at room temperature during regional anaesthesia with no risk of bacterial growth.

Diffusion of levofloxacin into bone and synovial tissues

OBJECTIVES

The degree of penetration of an antibiotic into the infected site is an important determinant of therapeutic success. Levofloxacin is widely used in the treatment of serious infections. However, there are only few studies concerning its diffusion into bone tissue and none concerning its diffusion into synovial tissue. Our objective was to quantify levofloxacin bone and synovial tissue penetration and to compare our data with the breakpoint for susceptible organisms.

PATIENTS AND METHODS

In an open-label study, 12 subjects who were undergoing elective total hip replacement received a single, parenteral, 500 mg dose of levofloxacin. Plasma, cortical and cancellous bone, and synovial tissue samples were collected a mean of 1.2 h later and analysed by a validated HPLC method.

RESULTS

The mean +/- S.D. plasma concentration of levofloxacin at the time of bone removal was 7.5 +/- 1.3 mg/L. The levofloxacin concentrations were 7.4 +/- 2.2 mg/kg in cancellous bone tissue and 3.9 +/- 1.2 mg/kg in cortical bone tissue. The levofloxacin concentration was 8.9 +/- 2.1 mg/kg in synovial tissue. The mean +/- S.D. ratios of levofloxacin concentration in bone and plasma (bone/plasma) were 1.0 +/- 0.4 for cancellous bone tissue and 0.5 +/- 0.1 for cortical bone tissue. The ratio of levofloxacin concentration in synovial tissue and plasma (synovial tissue/plasma) was 1.2 +/- 0.4.

CONCLUSIONS

The concentrations of levofloxacin achieved in cancellous and cortical bone tissue and in synovial tissue are greater than the breakpoint for susceptible organisms, which is < or =2 mg/L.

Determination of levofloxacin in plasma, bronchoalveolar lavage and bone tissues by high-performance liquid chromatography with ultraviolet detection using a fully automated extraction method

The aim of this study was to develop a specific and sensitive high-performance liquid chromatographic (HPLC) assay for the determination of levofloxacin in human plasma, bronchoalveolar lavage and bone tissues. The sample extraction was based on a fully automated liquid-solid extraction with an OASIS cartridge. The method used ultraviolet detection set at a wavelength of 299 nm and a separation with a Supelcosil ABZ+ column. The assay has been found linear over the concentration range 0.25-25 microg/ml for levofloxacin in plasma, 1-6 microg/ml in bronchoalveolar lavage and 0.5-10 microg/g for bone tissues and it provided good validation data for accuracy and precision. The assay will be applied to determine the penetration of levofloxacin in human bronchoalveolar lavage (BAL) and bone tissues during pharmacokinetic steady state.

Diffusion of cefepime into cancellous and cortical bone tissue

The degree of penetration of an antibiotic into the infection site is an important factor in its therapeutic efficacy, particularly in bone and joint infections. In the present study, we examined the bone tissue penetration of cefepime at a dose of 2 g, and the results were correlated to microbiological data to estimate the clinical efficacy of cefepime in bone infections. In this open-label, single-arm, noncomparative study, subjects of similar age, body weight, height and creatinine clearance who were undergoing elective total hip replacement received a single, parenteral 2 g dose of cefepime. Plasma samples were collected simultaneously with bone tissue samples 1.5 hours later, on average, and analyzed by a validated high performance liquid chromatography assay. Ten patients (7 women and 3 men; mean age, 78 years; mean body weight, 57 Kg; mean creatinine clearance, 56 mL/min) were enrolled. The mean +/- SD plasma concentration of cefepime at the time of bone removal was 72.9 +/- 24.4 microg/mL. The mean +/- SD cefepime concentrations were 73.5 +/- 16.2 microg/mL in cancellous bone tissue and 67.7 +/- 17.0 microg/mL in cortical bone tissue. The mean +/- SD ratios of cefepime concentration in bone and plasma (bone/plasma) were 1.06 +/- 0.23 for cancellous bone tissue and 0.87 +/- 0.37 for cortical bone tissue. Cefepime exhibits an excellent diffusion into bone tissue, with concentrations achieved in both cancellous and cortical bone tissue greater than the minimum concentrations required to inhibit the growth of 90% of strains (MIC90) of most of the susceptible pathogens commonly involved in bone infections.

Intrathecal morphine overdose during combined spinal-epidural block for Caesarean delivery

We describe a 25 mg intrathecal morphine overdose during a combined spinal-epidural block for a Caesarean delivery. Naloxone infusion (5.24 mg over 24 h) was started prior to the patient becoming symptomatic and almost immediately after the overdose. Invasive therapeutics such as mechanical ventilation were avoided.

Diffusion of isepamicin into cancellous and cortical bone tissue

The degree of penetration of an antibiotic into the infection site is an important factor in its therapeutic efficacy, particularly in bone and joint infections. In the present study, we examined the bone tissue penetration of isepamicin at a dose of 15 mg/Kg, and the results were correlated to microbiologic data to estimate the clinical efficacy of isepamicin in bone infections. In this open-label, single-arm, noncomparative study, subjects of similar age, body weight, height and creatinine clearance who were undergoing elective total hip replacement received a single, parenteral 15 mg/Kg dose of isepamicin. Plasma and bone tissue samples were collected a mean 1.3 hours later and analyzed by a high-pressure liquid chromatography method. Twelve patients (3 men and 9 women; mean age, 73.5 years; mean body weight, 53.5 Kg, mean creatinine clearance, 58.5 mL/min) were enrolled. The mean +/- SD plasma concentration of isepamicin at the time of bone removal was 43.0 +/- 10.4 microg/mL. The mean +/- SD isepamicin concentrations were 11.6 +/- 7.1 microg/mL in cancellous bone tissue and 12.0 +/- 7.3 microg/mL in cortical bone tissue. The mean +/- SD ratios of isepamicin concentration in bone and plasma (bone/plasma) were 0.28 +/- 0.14 for cancellous bone tissue and 0.31 +/- 0.20 for cortical bone tissue. The concentrations achieved in both cancellous and cortical bone tissue were greater than the minimum concentrations required to inhibit the growth of 90% of strains (MIC90) of most of the susceptible pathogens commonly involved in bone infections.

Pharmacokinetic parameters of ciprofloxacin (500 mg/5 mL) oral suspension in critically ill patients with severe bacterial pneumonia: a comparison of two dosages

The authors determined the pharmacokinetic parameters of a new immediate-release ciprofloxacin suspension in tube-fed intensive care patients with bacterial pneumonia, to compare two dosage regimens: 500 mg b.i.d and 750 mg b.i.d. in this prospective clinical trial. The 20 patients were critically ill and on mechanical ventilation and enteral feeding with bacterial pneumonia. They were randomized to receive two different ciprofloxacin dosages: 500 mg b.i.d (group 1) versus 750 mg b.i.d. (group 2). Blood samples were collected from these patients after reaching steady-state and the pharmacokinetic parameters were determined. The mean (range) serum steady-state concentration at 2 h after enteral administration was: C(max 500) = 2.6 (1.2-4.3) mg/L in group 1 and C(max 750) = 3.5 (1.5-5.9) mg/L in group 2. The mean (range) calculated 12-h area under the serum concentration was high in both groups: AUC(0-12 (500)) = 24.7 (12.9-36.2) mg.h/L in group 1 and AUC(0-12 (750)) = 28.9 (18.3-47.5) mg.h/L in group 2. In conclusion, ciprofloxacin oral suspension was well absorbed via nasogastric route in intensive care patients with severe pneumonia, achieving reliable pharmacokinetic parameters for most of the pathogens and important cost reduction compared to intravenous delivery. However, with less susceptible pathogens such as Staphylococcus aureus or Pseudomonas aeruginosa, higher dosages than 750 mg b.i.d. should be given.

Penetration of piperacillin/tazobactam (4 g/500 mg) into synovial tissue

The degree of penetration of an antibiotic into the infected site is an important criterion for therapeutic success. This is particularly true for bone and joint infections. The association of piperacillin and tazobactam has been widely used in the treatment of serious infections including bone infections, but no study has been devoted to the subject of its diffusion into synovial tissue. Our objective was to quantify piperacillin/tazobactam synovial tissue penetration and to estimate the efficacy of the association against the microorganisms usually encountered in joint infections. In an open-label study, 6 subjects with similar age, weight, height and creatinine clearance, who were undergoing elective total hip replacement, received a single, parenteral, 4 g/500 mg dose of piperacillin/tazobactam. Plasma and synovial tissue samples were collected and analyzed by a validated HPLC method. The mean concentrations of piperacillin and tazobactam 1.5 h after the initiation of infusion were 69.9 +/- 4.9 microg/mL and 7.7 +/- 0.3 microg/mL, respectively, in plasma and 37.1 +/- 2.1 microg/g and 2.8 +/- 0.4 microg/g, respectively, in synovial tissue. The synovial tissue/plasma ratios were 0.5 +/- 0.0 for piperacillin and 0.4 +/- 0.0 for tazobactam. The piperacillin/tazobactam ratios were 9.1:1 in plasma and 13.5:1 in synovial tissue. The concentrations achieved in synovial tissue are above the MICs of most of the susceptible pathogens usually involved in joint infections, which suggests that the piperacillin/tazobactam combination should be effective in the treatment of most joint infections caused by susceptible microorganisms.

[Pulmonary diffusion of antibiotics. Critical analysis of the literature]

OBJECTIVES

Collect exhaustive data from the literature concerning the diffusion of antibiotics into lung tissue and calculate their inhibitory quotient towards the germs most frequently encountered in pulmonary infections.

DATA SOURCES

Review of the literature. Data collected from the Medline database with the key words: lung, diffusion, disposition, antibiotics. Inhibitory quotients calculated from these data.

RESULTS

The results were relatively similar for the different types of samples, though some differences existed between the studies. These differences were caused in particular by methodological difficulties for the tissue dosage of antibiotics.

CONCLUSION

Further standardized studies, measuring in particular the antibiotic concentration in the epithelial lining fluid and in the alveolar macrophages, are necessary to obtain more reliable results in terms of inhibitory quotients. Only clinical studies, perhaps with the help of these data, could establish the real efficiency of antibiotics in lung infections.

Pressurized liquid extraction of lipids for the determination of oxysterols in egg-containing food

Pressurized liquid extraction (PLE, ASE) was compared with the Folch procedure (a solid-liquid extraction with chloroform/methanol 2:1, v/v) for the lipid extraction of egg-containing food; the accuracy of PLE for the quantitative determination of oxysterols in whole egg powder was evaluated. Samples of spray-dried whole egg, an Italian vanilla cake (Pandoro) and egg noodles were used. Two different extraction solvents (chloroform/methanol 2:1, v/v, and hexane/isopropanol 3:2, v/v) were tested at different extraction temperatures and pressures (60 degrees C at 15 MPa, 100 degrees C at 15 MPa, 120 degrees C at 20 MPa). No significant differences in the lipid recovery of the egg powder sample using PLE were found. However, PLE of the vanilla cake and egg noodles with the chloroform/methanol mixture was not selective enough and led to the extraction of a non-lipid fraction, including nitrogen-containing compounds. In the same samples, the pressurized hexane/isopropanol mixture gave a better recovery result, comparable to that obtained using the Folch method. Cholesterol oxidation products of the Folch extract and the pressurized liquid extract of spray dried egg powder (obtained with hexane/isopropanol 3:2, v/v, at 60 degrees C and 15 MPa) were determined by gas chromatography. PLE performed under these conditions is suitable to replace the Folch extraction, because the differences between the two methods tested were not statistically significant. Moreover, PLE shows important advantages, since the analysis time was shortened by a factor of 10, the solvent costs were reduced by 80% and the use of chlorinated solvents was avoided.

The analgesic effect of sufentanil combined with ropivacaine 0.2% for labor analgesia: a comparison of three sufentanil doses

The combination of opioids with local anesthetics is commonly used for epidural labor analgesia. We examined whether increasing sufentanil in doses of 5, 10, and 15 microg prolonged the duration of labor analgesia produced by ropivacaine. One hundred healthy parturients in the first stage of labor who requested epidural analgesia were enrolled. Parturients were randomized to receive 12 mL ropivacaine 0.2% alone or with sufentanil 5 microg, sufentanil 10 microg, or sufentanil 15 microg. The duration of analgesia, pain score, degree of motor blockade (using a four-point Bromage scale), heart rate, blood pressure, respiratory rate, oxygen saturation, and incidence of nausea and pruritus were recorded. The mean duration of epidural analgesia was 96 +/- 32 min for patients without sufentanil, 134 +/- 27 min for Group 5 (p < 0.01 versus control), 135 +/- 33 min for Group 10 (p < 0.01 versus control), 130 +/- 33 min for Group 15 (p < 0.01 versus control) without differences among sufentanil groups. Between 30 and 90 min, the sufentanil groups (5 microg, 10 microg, and 15 microg) had lower pain scores than the control group (p < 0.01 versus control) but there were no differences among the sufentanil groups. No patient in any group had a Bromage score more than 1. No significant difference was found for opioid-related side effects. We conclude that 5-10 or 15 microg sufentanil induced a similar prolongation of analgesia when combined with ropivacaine 0.2% for initiation of labor analgesia.

IMPLICATIONS

We studied the effect of adding one of three possible sufentanil doses to epidural ropivacaine 0.2% for labor analgesia. Adding sufentanil increased the duration of analgesia but there was no advantage in adding more than 5 microg of sufentanil.

Determination of furan fatty acids in extra virgin olive oil

The presence of 4 different furan fatty acids (F-acids) was detected in 18 samples of transmethylated monovarietal extra virgin olive oil: methyl 10,13-epoxy-11,12-dimethyloctadeca-10,12-dienoate [diMeF(9,5)], methyl 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoate [diMeF(11,5)] and both olefinic derivatives of diMeF(11,5) with one unsaturation on the side chains conjugated with the furan ring. Transmethylated oils were analyzed by normal phase high-performance liquid chromatography coupled on-line with capillary gas chromatography. After the gas chromatographic separation step, a more selective detection of F-acids was achieved by using a photoionization detector mounted in series with a flame ionization detector. The concentration of F-acids ranged between 50 ppb (detection limit of the method) and 2.1 ppm in the oil. The olefinic derivatives of diMeF(11,5) acids detected were not artifacts created during the sample preparation or during the chromatographic analysis.

[Diffusion in bone tissue of antibiotics]

DIFFICULT ASSESSMENT: Bone and joint infections are difficult to treat. Therapeutic success depends greatly on the diffusion of antibiotics into bone tissue. Few studies have been devoted to this subject and the variable nature of those reported hinders interpretation. Bone biopsies are generally obtained during orthopedic procedures. Antibiotic administration routes vary although intravenous infusion predominates. Agar gel diffusion is generally used for antibiotic assays but methodology varies depending of the study. The most recent reports use high-performance liquid chromatography. DIFFUSION STUDIES: The different studies examining antibiotic diffusion in bone tissue describe three classes: good diffusion (greater than 30%), moderate diffusion (between 15% and 30%), and low diffusion (less than 15%). Antibiotics in the good diffusion class include fluoroquinolones, teicoplanin, macrolides, rifampicin and trimethoprime. Antibiotics with moderate bone diffusion are ureidopenicillins, second and third generation cephalosporins, aminoglycosides, clindamycin, fosfomycin and vancomycin. Those with low bone diffusion are aminopenicillins, penicillin M and first generation cephalosporins. No data is available on the bone diffusion of pristinamycin. DATA INTERPRETATION: The clinical impact of these classifications must be interpreted with precaution when considering bone and joint infections as they were established on the basis of pharmacokinetic studies and not clinical trials. They would however appear to be useful in guiding antibiotic prophylaxis for orthopedic surgery in protocols with administration conditions and concentration goals similar to the experimental conditions. PRACTICAL ATTITUDES: These laboratory results could be used in clinical practice by comparing the MIC50 of the germs regularly encountered in bone infections (staphylococci, streptococci including enterococci, Gram negative bacilli including P. aeruginosa and H. influenzae) with concentrations obtained in the different studies, i.e. by calculating the inhibitor coefficient (IQ) of each antibiotic for each susceptible germ. This gives a classification by efficacy (excellent IQ > 10, good 1 < IQ < 10, poor IQ < 1) useful for guiding antibiotic choice in the difficult situation of bone and joint infection.

Determination of imidazole antimycotics in creams by supercritical fluid extraction and derivative UV spectroscopy

A supercritical fluid extraction (SFE) method was developed for the isolation of imidazole antimycotic drugs (miconazole, econazole, clotrimazole and bifonazole) from cream preparations. The SFE process involved static (1 min) and dynamic (4 min) extraction steps using pure and 10% methanol modified carbon dioxide. The SFE step was then followed by derivative UV spectrophotometric analysis. The method proved to be suitable for quality control assays of the examined antimycotics in commercial cream formulations.