B. Debaene

Accuracy of respiratory rate monitoring using a non-invasive acoustic method after general anaesthesia

BACKGROUNDnRespiratory rate should be monitored continuously in the post-anaesthesia care unit (PACU) to avoid any delay in the detection of respiratory depression. Capnometry is the standard of care but in extubated patients requires a nasal cannula or a face mask that may be poorly tolerated or can be dislodged, leading to errors in data acquisition and false alarms. The value of a new non-invasive acoustic monitor in this setting has not been fully investigated.nnnMETHODSnAdult patients admitted to the PACU after general anaesthesia were included. After tracheal extubation, an adhesive sensor with an integrated acoustic transducer (RRa™) was placed on the patients throat and connected to its monitor while the patient breathed through a face mask with a carbon dioxide sampling port (Capnomask™) connected to a capnometer. Both the acoustic monitor and the capnometer were connected to a computer to record one pair of data per second for up to 60 min.nnnRESULTSnFifty-two patients, mean (range) age 54 (22-84) yr and BMI 26 (19-39) kg m(-2), were studied. Compared with capnometry, the bias and limits of agreement of the acoustic method were 0 (-1.4-1.4) bpm. The acoustic sensor was well tolerated while the face mask was removed by eight patients, leading to study discontinuation in two patients.nnnCONCLUSIONSnIn extubated patients, continuous assessment of respiration rate with an acoustic monitor correlated well with capnometry.

Effects of Ketamine, Halothane, Enflurane, and Isoflurane on Systemic and Splanchnic Hemodynamics in Normovolemic and Hypovolemic Cirrhotic Rats

The effects of ketamine, halothane, enflurane, and isoflurane on systemic and splanchnic hemodynamics in cirrhotic rats that were either normovolemic or hypovolemic following hemorrhage were characterized. Rats received at random either ketamine (30 mg/kg iv, 1.5 mg.kg-1.min-1 iv), halothane, enflurane, or isoflurane (1 MAC). Conscious rats were considered the control group. Four weeks before hemodynamic studies bile duct ligation was performed in all rats to induce cirrhosis. Hemodynamic measurements were performed using the radioactive microsphere method 1 h after the onset of anesthesia and 30 min after hemorrhage. Anesthetized rat lungs were mechanically ventilated with room air. Before hemorrhage cardiac index was higher in conscious rats and in rats receiving isoflurane than in the other groups (P less than 0.001). Hepatic arterial blood flow was similar in conscious rats and in those receiving isoflurane or halothane and was higher than in those receiving ketamine or enflurane. The lowest splanchnic and portal venous tributary blood flows were observed in rats receiving enflurane. After hemorrhage cardiac index was significantly less than before hemorrhage in all groups, except in rats receiving enflurane. After hemorrhage portal venous tributary blood flow decreased significantly in all groups except in enflurane group. During halothane and enflurane anesthesia hepatic arterial blood flow and hepatic arterial fraction of cardiac output decreased (P less than 0.01) and they were maintained in the other groups. After hemorrhage hepatic arterial fraction of cardiac output in conscious rats was higher than in those receiving ketamine, halothane, or enflurane (P less than 0.05) and was similar to those receiving isoflurane.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of haemoglobin measurement methods in the operating theatre

BACKGROUNDnVarious methods of haemoglobin (Hb) measurement are available to guide transfusion including several methods that allow for measurement at the bedside. This study directly compared their absolute and trend accuracy compared with values from the central lab (reference method).nnnMETHODSnAdult patients undergoing surgery with expected blood loss wore a rainbow ReSposable sensor connected to a Radical-7 Pulse CO-Oximeter (SpHb). Arterial samples were analysed with a haematology analyser (HbLab), a satellite CO-Oximeter (HbSat), and a point-of-care haemoglobinometer (HemoCue; HcueArt). Concomitantly, ear capillary blood was tested using the same haemoglobinometer (HcueCap). Absolute accuracy and the clinical significance of error were assessed with Bland-Altman plots and three-zone error grids. Trend analysis was performed using a modified polar plot, testing both directionality and magnitude of Hb changes compared with the reference.nnnRESULTSnTwo hundred and nineteen measurements from 53 patients with HbLab ranging between 6.8 and 16.3 g dl(-1) (4.2 and 10.1 mmol litre(-1)) were recorded. Compared with the reference method, bias (precision) was 0.2 (0.2) g dl(-1) [0.1 (0.1) mmol litre(-1)] for HcueArt, 0.8 (0.3) g dl(-1) [0.5 (0.2) mmol litre(-1)] for HbSat, 0.5 (0.5) g dl(-1) [0.3 (0.3) mmol litre(-1)] for HcueCap and 1.0 (1.2) g dl(-1) [0.6 (0.7) mmol litre(-1)] for SpHb. None of the devices tested would have led to unnecessary or delayed transfusion according to 2006 ASA transfusion criteria. Trend accuracy was better for HcueArt and HbSat than for HcueCap and SpHb.nnnCONCLUSIONnBedside Hb measurement methods differ in their agreement to a laboratory haematology analyser but none would have led to transfusion errors. Trial Registry Number RCB 2009-AO1144-53.

Accuracy of respiratory rate monitoring by capnometry using the Capnomask® in extubated patients receiving supplemental oxygen after surgery

BACKGROUNDnRespiratory monitoring is standard after anaesthesia and surgery. Abnormal respiratory rate is a sensitive indicator of respiratory problems, even in patients receiving supplemental oxygen, but the best method for its continuous measurement in spontaneously breathing patients is unclear. This study compared respiratory rate assessment by capnometry using a new oxygen mask with a carbon dioxide sampling port (Capnomask(®)) and thoracic impedance pneumography with clinical measurement (used as a reference method) in extubated patients receiving supplemental oxygen.nnnMETHODSnAdult males admitted to the post-anaesthesia care unit after general anaesthesia were studied. Immediately after extubation, a Capnomask(®) connected to a capnometer was positioned appropriately. Respiratory rate was measured by visual inspection of chest movement for 1 min, by capnometry, and thoracic impedance pneumography. One set of measurements was obtained for every patient receiving supplemental oxygen at different flow rates.nnnRESULTSnTwenty men, mean (inter-quartile range) age 54 (23-66) yr and BMI 25 (21-31) kg m(-2), were studied. Compared with visual inspection, the bias and limits of agreement were 0.0 (1.0 to -1.0) bpm for the Capnomask(®) and -2.2 (2.0 to -6.5) bpm for the impedance pneumography. The accuracy of respiratory rate assessment using Capnomask(®) was not influenced by the supplemental oxygen flow rate.nnnCONCLUSIONSnIn extubated patients, continuous assessment of respiratory rate with the Capnomask(®) is more accurate than by thoracic impedance pneumography even when supplemental oxygen is delivered at a high flow rate.

Indwelling time and risk of colonization of peripheral arterial catheters in critically ill patients

ObjectiveDespite the lack of evidence to support routine scheduled replacement of peripheral arterial catheters this practice continues to be widely used in many intensive care units (ICU). This study evaluated whether additional risks of catheter colonization are incurred with a conservative attitude in severely ill patients.Design and settingObservational study over a 18-month period in a 15-bed surgical ICU of a 1,000-bed French university-affiliated hospital.CathetersA total of 295 peripheral arterial catheters were inserted in 295 patients.Measurements and main resultsHazard rates of catheters colonization (defined as quantitative culture of a catheter tip showing at least one microorganism at a concentration of 1,000 or more colony-forming units per milliliter) according to indwelling time were determined over 5-day periods by survival analysis. The mean indwelling time was 8xa0±xa06xa0days (median 6xa0days). Overall, 47 (16%) colonization episodes were diagnosed, leading to catheter colonization incidence density of 19.9 per 1,000 catheter-days. Risk factors for catheters colonization increase in proportion to the duration of catheter use. Hazard rates of catheter colonization were 1.0, 1.9, 3.5, 7.0, 6.0 and 5.7%, for the 111 arterial catheters left in place for 4xa0days or less, 5–9xa0days (87 catheters), 10–14xa0days (55 catheters), 15–19xa0days (27 catheters), 20–24xa0days (10 catheters) and more than 24xa0days (5 catheters).ConclusionsSystematic replacement of peripheral arterial catheters might be useful in preventing catheter-related colonization, especially after 2xa0weeks of use.

Evaluation of acoustic respiration rate monitoring after extubation in intensive care unit patients

1 Bellomo R, Bion J, Finfer S, Myburgh J, Perner A, Reinhart K. Open letter to the Executive Director of the European Medicine Agency concerning the licensing of hydroxyethyl starch solutions for fluid resuscitation. Br J Anaesth 2014; 112: 595–600 2 Brunkhorst FM, Engel C, Bloos F, et al. Intensive insulin therapy and pentastarch resuscitation in severe sepsis. N Engl J Med 2008; 358: 125–39 3 Perner A, Haase N, Guttormsen AB, et al. Hydroxyethyl starch 130/ 0.42 versus Ringer’s acetate in severe sepsis. N Engl J Med 2012; 367: 124–34 4 Myburgh JA, Finfer S, Bellomo R, et al. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med 2012; 367: 1901–11 and Supplement to: Myburgh JA, Finfer S, Bellomo R, et al. Hydroxyethyl starch or saline for fluid resuscitation in intensive care. N Engl J Med 2012. doi:10.1056/ NEJMoa1209759 5 Van Der Linden P, James M, Mythen M, et al. Safety of modern starches used during surgery. Anesth Analg 2013; 116: 35–48 6 Martin C, Jacob M, Vicaut E, et al. Effect of waxy maize-derived hydroxyethyl starch 130/0.4 on renal function in surgical patients. Anesthesiology 2013; 118: 387–94 7 Annane D, Siami S, Jaber S, et al. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock—the CRISTAL randomized trial. J Am Med Assoc 2013; 310: 1809–17 8 James MF, Michell WL, Joubert IA, et al. Resuscitation with hydroxyethyl starch improves renal function and lactate clearance in penetrating trauma in a randomized controlled study: the FIRST trial (Fluids in Resuscitation of Severe Trauma). Br J Anaesth 2011; 107: 693–702 9 Cittanova ML, Leblanc I, Legendre C, et al. Effect of hydroxyethylstarch in brain-dead kidney donors on renal function in kidneytransplant recipients. Lancet 1996; 348: 1620–22 10 Rational fluid therapy in Germany (RaFTinG). Available on ClinicalTrials.gov (NCT01122277) last updated on 7 July 2011. http://clinical trials.gov/ct2/show/NCT01122277?term1⁄4NCT01122277&rank1⁄41 11 Meybohm P, Van Aken H, De Gasperi A, et al. Re-evaluating currently available data and suggestions for planning randomised controlled studies regarding the use of hydroxyethyl-starch in critically ill patients—a multidisciplinary statement. Crit Care 2013; 17: R166 (Epub ahead of print)

Microdialysis Study of Cefotaxime Cerebral Distribution in Patients with Acute Brain Injury

ABSTRACT Central nervous system (CNS) antibiotic distribution was described mainly from cerebrospinal fluid data, and only few data exist on brain extracellular fluid concentrations. The aim of this study was to describe brain distribution of cefotaxime (2 g/8 h) by microdialysis in patients with acute brain injury who were treated for a lung infection. Microdialysis probes were inserted into healthy brain tissue of five critical care patients. Plasma and unbound brain concentrations were determined at steady state by high-performance liquid chromatography. In vivo recoveries were determined individually using retrodialysis by drug. Noncompartmental and compartmental pharmacokinetic analyses were performed. Unbound cefotaxime brain concentrations were much lower than corresponding plasma concentrations, with a mean cefotaxime unbound brain-to-plasma area under the curve ratio equal to 26.1 ± 12.1%. This result was in accordance with the brain input-to-brain output clearances ratio (CLin,brain/CLout,brain). Unbound brain concentrations were then simulated at two dosing regimens (4 g every 6 h or 8 h), and the time over the MICs (T>MIC) was estimated for breakpoints of susceptible and resistant Streptococcus pneumoniae strains. T>MIC was higher than 90% of the dosing interval for both dosing regimens for susceptible strains and only for 4 g every 6 h for resistant ones. In conclusion, brain distribution of cefotaxime was well described by microdialysis in patients and was limited.

Prevention of drug delivery disturbances during continuous intravenous infusion: an in vitro study on a new multi-lumen infusion access device.

OBJECTIVEnStopping and restarting carrier fluid flow and performing simultaneous drug infusions can lead to hazardous disturbances in drug delivery. The present study was designed to assess in vitro whether using a multi-lumen infusion access device could prevent noradrenaline disturbances.nnnSTUDY DESIGNnIn vitro laboratory work.nnnMETHODSnTwo infusion devices were studied: a standard device with a four-port manifold and a 150cm extension line and a nine-lumen infusion device (Edelvaiss-Multiline(®)) with eight accesses connected to nine separate lumens in a single tube of 150cm: seven accesses connected to seven peripheral lumens and one for the carrier fluid access connected to two lumens. Two experimental protocols of noradrenaline infusion were made: (a) drug flow rate change and (b) stop-and-go carrier fluid flows. Two parameters were studied: drug mass flow rate and flow change efficiency (FCE) calculated from the ratio of the area under the experimental mass flow rate curve to the area under the theoretical instantaneous mass flow rate curve.nnnRESULTSnVariations in noradrenaline mass flow rate were more rapid with the Edelvaiss-Multiline(®) when the noradrenaline infusion rate was increased or decreased. FCE was significantly different from one infusion device to the other during both noradrenaline flow rate increase (standard vs. nine-lumen: 58% vs. 84%; P=0.008) and decrease (175% vs. 108%; P=0.008). Decreased drug delivery after stopping carrier fluid flow (standard vs. nine-lumen: 21% vs. 98%; P=0.008) and sudden temporary increases on resumption (253% vs. 103%; P=0.008) were reduced in magnitude and duration when using the Edelvaiss-Multiline(®) with a significant difference in FCE between the two infusion devices.nnnCONCLUSIONSnUsing the nine-lumen infusion device reduces drug delivery disturbances during continuous intravenous infusion.

Case Report: Perioperative immediate hypersensitivity involves not only allergy but also mastocytosis

PurposeWe report a case of drug-induced immediate hypersensitivity occurring after atracurium injection in a patient with cutaneous mastocytosis.Clinical featuresA 69-yr-old woman was scheduled for hysterectomy. She was premedicated with hydroxyzine, and anesthesia was induced with sufentanil, propofol, and atracurium. Within two to three minutes following the injection of atracurium, the patient experienced an episode of generalized erythema and arterial hypotension associated with tachycardia. No bronchospasm was observed. Her cardiovascular signs resolved spontaneously within five minutes, while her cutaneous signs disappeared within 30xa0min. Anesthesia and surgery remained uneventful. The patient’s serum tryptase levels were measured at different time points following the clinical reaction. An in vitro flow cytometry-based basophil activation test was performed with atracurium, and in vivo skin tests to latex and all drugs which were administered just before the clinical reaction were also done. The serum tryptase showed increased concentrations that remained elevated for 24 hr, 48 hr, and even four weeks after the clinical reaction. Atracurium did not induce either CD63 or CD203c upregulation, and the skin tests were negative in response to the medications received (propofol, sufentanil, and atracurium) as well as to latex.ConclusionsAllergic hypersensitivity to atracurium was ruled out. Increased tryptase concentrations following the clinical reaction, persistent increased levels of basal serum tryptase, and negative skin tests suggested the onset of mast cell degranulation in a patient with mastocytosis. Immediate reaction occurring in patients with mastocytosis should be investigated in order to identify the mechanism of the reaction, either histamine release due to the disease itself or due to a concurrent drug/agent-induced IgE-mediated mechanism.RésuméObjectifNous rapportons une réaction d’hypersensibilité immédiate documentée survenue après injection d’atracurium chez une patiente atteinte de mastocytose cutanée.Éléments cliniquesUne hystérectomie était programmée chez une patiente âgée de 69 ans, prémédiquée par hydroxyzine. L’induction anesthésique associait sufentanil, propofol et atracurium. Un érythème généralisé suivi d’une hypotension artérielle associée à une tachycardie est survenu deux à trois minutes aprèsxa0l’injection d’atracurium. Aucun bronchospasme n’a été observé. Les signes cardiovasculaires étaient résolutifs en moins de cinq minutes et les signes cutanés ont disparu en 30xa0min. La chirurgie et l’anesthésie ont eu lieu sans incidents. La concentration de tryptase sérique a été mesurée à différents moments après la réaction clinique. Un test d’activation in vitro des basophiles avec atracurium ainsi que des tests cutanés avec le latex et les médicaments injectés juste avant la réaction clinique ont été réalisés.RésultatsLes concentrations de tryptase sérique étaient augmentées immédiatement après la réaction clinique ainsi que 24xa0h, 48xa0h et quatre semaines après. Aucune expression à la hausse des récepteurs CD63 ou CD203c n’a été observée en présence d’atracurium. Les tests cutanés sont demeurés négatifs aux médicaments (propofol, sufentanil et atracurium) et avec le latex.ConclusionUne hypersensibilité allergique à l’atracurium a été écartée. L’augmentation des concentrations de tryptase immédiatement après la réaction clinique et leur persistance à distance, associée à la négativité des tests cutanés, suggéraient une dégranulation mastocytaire chez une patiente atteinte de mastocytose. Une réaction immédiate chez un patient atteint de mastocytose doit être documentée afin d’identifier le mécanisme de la réaction (histaminolibération non spécifique imputable à la maladie elle-même ou bien anaphylaxie IgE-médiée à un médicament/agent).

Enquête nationale sur le marquage des seringues d’anesthésie en France

INTRODUCTIONnThe French Society of Anaesthesiology (SFAR) recommends the use of pre printed self-stick syringe labels. However, French anaesthesia-syringe labelling customs is yet unknown.nnnSTUDY DESIGNnTherefore, a national phone survey was performed in order to investigate this issue.nnnRESULTSnForty-five percent of the answering centers (324/722) used colour self-stick labels, with a larger proportion in public centers and a large regional variability. The kind of colour code differed from an area to another. Among centers using colour labels, the international recommended colour code was used in only 36% of them. The majority of health care providers declare to be favourable to the use of the colour self-stick labels and the standardization of the colour code as well. A relationship between the University hospital and the surrounded area has been observed for the use of the colour labels and the choice of the colour code.nnnCONCLUSIONnColour labels are used in France by nearly half of the centers, but international colour code is less spread.