In vitro comparison of epidural bacteria filters permeability and screening scanning electron microscopy / Comparação in vitro da permeabilidade de filtros epidurais antibacterianos e triagem por microscopia eletrônica de varredura

BACKGROUND AND OBJECTIVES: Epidural catheter bacteria filters are barriers in the patient-controlled analgesia/anaesthesia for preventing contamination at the epidural insertion site. The efficiency of these filters varies according to pore sizes and materials. METHOD: The bacterial adhesion capability of the two filters was measured in vitro experiment. Adhesion capacities for standard Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853) strains of the two different filters (Portex and Rusch) which have the same pore size were examined. Bacterial suspension of 0.5 Mc Farland was placed in the patient-controlled analgesia pump, was filtered at a speed of 5 mL/h. in continuous infusion for 48 h and accumulated in bottle. The two filters were compared with colony counts of bacteria in the filters and bottles. At the same time, the filters and adhered bacteria were monitored by scanning electron microscope. RESULTS: Electron microscopic examination of filters showed that the Portex filter had a granular and the Rusch filter fibrillary structure. Colony counting from the catheter and bottle showed that both of the filters have significant bacterial adhesion capability (p < 0.001). After the bacteria suspension infusion, colony countings showed that the Portex filter was more efficient (p < 0.001). There was not any difference between S. aureus and P. aeruginosa bacteria adhesion. In the SEM monitoring after the infusion, it was physically shown that the bacteria were adhered efficiently by both of the filters. CONCLUSION: The granular structured filter was found statistically and significantly more successful than the fibrial. Although the pore sizes of the filters were same - of which structural differences shown by SEM were the same - it would not be right to attribute the changes in the efficiencies to only structural differences. Using microbiological and physical proofs with regard to efficiency at the same time has been another important aspect of this experiment.

JUSTIFICATIVA E OBJETIVOS: Os filtros antibacterianos para cateter epidural são barreiras da analgesia/anestesia controlada pelo paciente para evitar a contaminação do local de inserção epidural. A eficácia desses filtros varia de acordo com o material e o tamanho dos poros. MÉTODO: A capacidade de aderência bacteriana dos dois filtros foi medida em experimento in vitro. Avaliamos a capacidade de aderência das cepas padrão de Staphylococcus aureus (ATCC 25923) e Pseudomonas aeruginosa (ATCC 27853) de dois filtros diferentes (Portex e Rusch), mas com poros do mesmo tamanho. Uma suspensão bacteriana grau 0,5 de McFarland foi colocada na bomba de analgesia controlada pelo paciente e filtrada a uma velocidade de 5 mL/h em infusão contínua por 48 horas e acumulada em frasco. Os dois filtros foram comparados com contagens de colônias de bactérias nos filtros e frascos. Ao mesmo tempo, os filtros e as bactérias aderidas foram monitorados com microscópio eletrônico de varredura. RESULTADOS: O exame dos filtros por microscópico eletrônico mostrou que a estrutura do filtro Portex era granulada e a do filtro Rusch fibrilar. A contagem de colônias do cateter e do frasco mostrou que ambos os filtros tinham uma capacidade de adesão bacteriana significativa (p < 0,001). Após a infusão da suspensão bacteriana, as contagens de colônias mostraram que o filtro Portex foi mais eficiente (p < 0,001). Não houve qualquer diferença entre as adesões de bactérias S. aureus e P. aeruginosa. Na monitoração por MEV após a infusão, ficou fisicamente evidente que as bactérias foram aderidas de modo eficaz por ambos os filtros. CONCLUSÃO: O filtro com estrutura granular foi estatística e significativamente mais bem- sucedido do que o filtro com estrutura fibrilar. Embora o tamanho dos poros dos filtros fosse igual - as diferenças estruturais mostradas pelo MEV eram semelhantes -, não seria justo atribuir as alterações de eficiência apenas às diferenças estruturais. O uso ao mesmo tempo de provas microbiológicas e físicas para avaliar a eficácia foi outro aspecto importante deste experimento.

In vitro comparison of epidural bacteria filters permeability and screening scanning electron microscopy.

BACKGROUND AND OBJECTIVES: Epidural catheter bacteria filters are barriers in the patient-controlled analgesia/anaesthesia for preventing contamination at the epidural insertion site. The efficiency of these filters varies according to pore sizes and materials. METHOD: The bacterial adhesion capability of the two filters was measured in vitro experiment. Adhesion capacities for standard Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853) strains of the two different filters (Portex and Rusch) which have the same pore size were examined. Bacterial suspension of 0.5 Mc Farland was placed in the patient-controlled analgesia pump, was filtered at a speed of 5 mL/h. in continuous infusion for 48 h and accumulated in bottle. The two filters were compared with colony counts of bacteria in the filters and bottles. At the same time, the filters and adhered bacteria were monitored by scanning electron microscope. RESULTS: Electron microscopic examination of filters showed that the Portex filter had a granular and the Rusch filter fibrillary structure. Colony counting from the catheter and bottle showed that both of the filters have significant bacterial adhesion capability (p<0.001). After the bacteria suspension infusion, colony countings showed that the Portex filter was more efficient (p<0.001). There was not any difference between S. aureus and P. aeruginosa bacteria adhesion. In the SEM monitoring after the infusion, it was physically shown that the bacteria were adhered efficiently by both of the filters. CONCLUSION: The granular structured filter was found statistically and significantly more successful than the fibrial. Although the pore sizes of the filters were same - of which structural differences shown by SEM were the same - it would not be right to attribute the changes in the efficiencies to only structural differences. Using microbiological and physical proofs with regard to efficiency at the same time has been another important aspect of this experiment.

[In vitro comparison of epidural bacteria filters permeability and screening scanning electron microscopy]. / Comparação in vitro da permeabilidade de filtros epidurais antibacterianos e triagem por microscopia eletrônica de varredura.

BACKGROUND AND OBJECTIVES: Epidural catheter bacteria filters are barriers in the patient-controlled analgesia/anaesthesia for preventing contamination at the epidural insertion site. The efficiency of these filters varies according to pore sizes and materials. METHOD: The bacterial adhesion capability of the two filters was measured in vitro experiment. Adhesion capacities for standard Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853) strains of the two different filters (Portex and Rusch) which have the same pore size were examined. Bacterial suspension of 0.5 Mc Farland was placed in the patient-controlled analgesia pump, was filtered at a speed of 5mL/h. in continuous infusion for 48h and accumulated in bottle. The two filters were compared with colony counts of bacteria in the filters and bottles. At the same time, the filters and adhered bacteria were monitored by scanning electron microscope. RESULTS: Electron microscopic examination of filters showed that the Portex filter had a granular and the Rusch filter fibrillary structure. Colony counting from the catheter and bottle showed that both of the filters have significant bacterial adhesion capability (p<0.001). After the bacteria suspension infusion, colony countings showed that the Portex filter was more efficient (p<0.001). There was not any difference between S. aureus and P. aeruginosa bacteria adhesion. In the SEM monitoring after the infusion, it was physically shown that the bacteria were adhered efficiently by both of the filters. CONCLUSION: The granular structured filter was found statistically and significantly more successful than the fibrial. Although the pore sizes of the filters were same - of which structural differences shown by SEM were the same - it would not be right to attribute the changes in the efficiencies to only structural differences. Using microbiological and physical proofs with regard to efficiency at the same time has been another important aspect of this experiment.

A possible perianesthetic serotonin syndrome related to intrathecal fentanyl.

Serotonin syndrome occurs with selective serotonin reuptake inhibitors, opioids, and other serotonergic agents. We describe a possible serotonin syndrome related to intrathecal fentanyl in a patient taking multiple drugs and substances such as ergot alkaloids, marijuana, methylenedioxy-N-methylamphetamine, and ephedrine.

The safe limits of mechanical factors in the apnea testing for the diagnosis of brain death.

Apneic oxygenation is an apnea testing method in the diagnosis of brain death. In this method, oxygen (O2) is delivered into the trachea via an O2 catheter (O2C). However, barotrauma may develop during O2 insufflation into the trachea. Oxygen catheter diameters, O2 catheter tip position in the trachea, and O2 flow rate have been proposed as causes of barotrauma. This study was designed to highlight the airway pressure changes during apneic oxygenation in a model consisting of an anesthesia bag, which was connected to a pressure transducer and to an endotracheal tube (ETT). The pressure of the system was monitored while delivering O2 continuously to the system through O2C of different diameters, which were placed in the ETT. Tested variables were ETT/O2C ratio, O2C tip position in ETT (proximal 1/3 of the ETT, mid point of the ETT, and distal 1/3 of the ETT) and O2 flow rate (6, 8, and 10 L min(-1)). The increase in the airway pressure significantly correlated with O2C tip position in ETT (p = 0.017). ETT/O2C ratio smaller than 1.75 caused significantly high airway pressures (p < 0.05). The pressure was significantly higher at the flow rate of 10 L min(-1) O2 compared with the flow rate of 6 L min(-1) O2 (p < 0.01). Thus, ETT/O2C ratio, O2C tip position in ETT and O2 flow rate are the important factors that determine the airway pressure in the trachea during O2 insufflation. In conclusion, overlooked mechanical factors dangerously increase airway pressure during apnea testing.

A new method for estimating arterial occlusion pressure in optimizing pneumatic tourniquet inflation pressure.

To reduce pressure-related injuries resulting from pneumatic tourniquet use, the lowest possible inflation pressure is recommended. Arterial occlusion pressure (AOP) is a measure of the cuff pressure required to maintain a bloodless surgical field. However, its determination method is time consuming, requires operator skill, and is therefore seldom used in current practice. An AOP estimation can be made by knowing the pressure transmitted to the underlying soft tissues. We measured upper and lower extremity tissue pressures under the tourniquet cuff at 100, 200, and 300 mm Hg of tourniquet inflation pressures in 30 anesthetized living adult patients. All patients received general anesthesia with neuromuscular relaxation. A Stryker intra-compartmental pressure monitor was used to measure tissue pressures under the tourniquet cuff. In all patients, the soft tissue pressures were consistently lower than the applied tourniquet inflation pressures. Our results revealed tissue padding coefficients for extremities 20 to 75 cm in circumferences. An estimation method of AOP was developed [AOP = (systolic blood pressure + 10)/Tissue padding coefficient]. The new AOP estimation method may be a simple, rapid, and clinically practical alternative to the AOP determination method.

The effects of gender and menopause on serum lidocaine levels in smokers.

It has been established that human cytochrome P450 (CYP) enzymatic activity is affected by gender, or by hormonal factors such as the menopause in women. Gender differences have a more pronounced effect on cytochrome (CYP) 3A4 isoenzyme activity, whereas cytochrome (CYP) 1A2 isoenzyme activity is mainly induced by chronic smoking. Lidocaine is frequently used in the treatment of hemodynamic changes following laryngoscopy and tracheal intubation during general anesthesia, and is metabolized by CYP3A4 and CYP1A2 isoenzymes in the liver. The aim of this study was investigate the effects of gender and menopause on serum lidocaine levels in smokers under general anesthesia. Six men, six premenopausal women and six postmenopausal women were enrolled in the study and received i.v. lidocaine (1 mg/kg) 1 minute before they underwent general anesthesia. Serum lidocaine concentrations were measured using the EMIT method at 1, 5, 10, 20, 40 and 60 minutes post-administration. Statistical analyses were performed using the Mann-Whitney U-test. No statistically significant differences were found regarding the area under curve (AUC(0-60) microg/mL/min), elimination half-life (t1/2 [min]) of lidocaine and in the measured levels of serum lidocaine at any time point between the study groups (p > 0.05). These results suggest that gender and menopause may have no significant effect on serum lidocaine levels in smokers.

Propofol and sevoflurane during epidural/general anesthesia: comparison of early recovery characteristics and pain relief.

We investigated the early recovery characteristics and pain relief of adult patients during combined anesthesia with (epidural and general), either with propofol or sevoflurane for maintenance in major abdominal surgery. Twenty-two patients (ASA I-III) were enrolled in this randomized, prospective study. After fluid preloading, 10 ml of bupivacaine 0.5% + 5 ml of prilocaine 0.5% + 1 ml of fentanyl 50 microg mL(-1) were administered via an epidural catheter. General anesthesia was induced with fentanyl and propofol after T6 sensorial blockade. Propofol group (n = 11) received propofol (2-5 mg kg(-1) h(-1)), sevoflurane group (n = 11) received sevoflurane (1-2%) for maintenance. Anesthesia was supplemented with N2O in O2 and intravenous fentanyl. Continuous epidural infusion of 0.125% bupivacaine + 1 microg fentanyl (5-7 mL h(-1)) was started forty-five min after the epidural bolus dose and 5 ml of it was given at the start of the wound closure. All anesthetics were discontinued except epidural infusion during the last suture. After emergence time was determined, the patients were transferred to the PACU. They were observed for orientation times of person and place. The pain scores (verbal analogue scale, 0-10) were assessed with 30 min intervals. When the patient's pain score was >3, rescue analgesic protocol (diclofenac Na 75 mg im followed by meperidine HCI approximately 0.25 mg kg(-1) iv at the latter period) was applied. In the case of inadequate pain relief during the latter assessment periods, meperidine HCI approximately 0.25 mg kg(-1) was administered. Mann-Whitney U test and Fisher's exact test were used for the statistical analysis. A value of p<0.05 was considered significant. Between the groups no statistical differences were observed in the emergence time (5 vs. 6 min, median) and in the orientation time to person (6 vs. 10 min). Recovery of orientation to place was found faster in propofol group (7 vs. 12 min, p = 0.041). Pain scores of the patients between the groups were not statistically different at 0, 30, 60, 90, 120 min postoperatively (3, 2, 3, 2, 2, and 2, 4, 4, 3, 3, respectively). Rescue analgesic protocol and additional meperidine HCI were applied to 63.6% and 45.4% of patients in the propofol group, 54.5% and 36.3% of patients in the sevoflurane group, respectively. There weren't any statistical differences in regard to these, either. Except orientation time to place, the times of emergence and orientation to person, the pain scores and the analgesic requirements of the patients in both groups were similar. Propofol or sevoflurane did not offer any advantages for postoperative pain relief on behalf of either one when combined with epidural anesthesia.

Dilution of rocuronium to 0.5 mg/mL with 0.9% NaCl eliminates the pain during intravenous injection in awake patients.

In a randomized, double-blinded, controlled study, we evaluated the effect of diluting rocuronium 10 mg/mL to 1 or 0.5 mg/mL with 0.9% NaCl on the pain associated with IV administration of rocuronium with small doses given before succinylcholine or nondepolarizing agent administration. One hundred fifty patients undergoing surgical procedures that required general anesthesia were randomized into three groups. Group 1 received rocuronium 10 mg/mL. Groups 2 and 3 received 1 and 0.5 mg/mL of rocuronium, respectively. Patient demographics, pain scores, osmolality, and the pH of the solutions were recorded. Group 1 had the most intense and frequent pain response. Eighty percent of patients in this group reported pain on injection. In Group 2, the incidence and intensity of pain were significantly less when compared with those of Group 1. In this group, 38% of patients reported pain during injection. In Group 3, none of the patients experienced pain on injection. The pH values and osmolalities of study solutions were not significantly different among groups. In conclusion, in awake patients, dilution of rocuronium 10 mg/mL at small doses given before succinylcholine or nondepolarizing agent administration of 0.06 mg/kg to 0.5 mg/mL with 0.9% NaCl is a simple and cost-effective strategy for preventing pain during IV rocuronium injection.

Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions.

BACKGROUND: In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures. METHODS: Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg x kg(-1). Following atropine 10 microg x kg(-1), remifentanil infusion 0.5 microg x kg(-1) x min(-1) was started. After 60 s, anesthesia was induced with propofol 2.5 mg x kg(-1). Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg x kg(-1) (group I, n = 22) or 0.3 mg x kg(-1) (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg x kg(-1) h(-1) was added to the infusion of remifentanil 0.5 microg x kg(-1) min(-1) for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals. RESULTS: Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity. CONCLUSIONS: The results suggest that 0.3 mg x kg(-1) of rocuronium may be a better low dose than 0.15 mg x kg(-1) of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.

Diltiazem provides higher internal mammary artery flow than nitroglycerin during coronary artery bypass grafting surgery.

OBJECTIVES: Perioperative internal mammary artery (IMA) vasospasm in patients undergoing coronary artery bypass grafting (CABG) surgery may lead to morbidity and mortality. Surgical stimulus is one of the common causes of IMA vasospasm. Preventive measures, beside treatment should be taken into consideration to obtain vasospasm free IMA. The effect of a pharmacologic agent on IMA flow when it is administered before harvesting the artery has not been documented. We designed a prospective randomized clinical study to compare the IMA free blood flows in patients receiving either diltiazem or nitroglycerin, starting infusion of study drugs before a surgical stimulus was applied to the IMA region and continuing throughout the isolation period. METHODS: Sixty patients undergoing elective CABG surgery with the left IMA received diltiazem (n=30, 0.05-0.1 mg/kg per hour) or nitroglycerin (n=30, 0.25-2.5 microg/kg per minute) in a randomized manner. Infusions of study drugs were started before applying a surgical stimulus to the IMA region and continued throughout the harvesting period. The first free flow was measured after IMA was cut above its bifurcation and the second after its distal segment was resected. Heart rate, temperature, mean arterial and central venous pressures were recorded. Data were analyzed with Student's t-test and Fischer's exact test. RESULTS: Preoperative and hemodynamic data were similar between the groups. The means of first and second IMA flows in patients treated with diltiazem (53.8+/-30.1 and 72.3+/-35.4 ml/min) were significantly higher than in those treated with nitroglycerin (25.7+/-16.2 and 48.9+/-23.8 ml/min; P=0.000, 0.004, respectively). IMA flows significantly increased after distal segment resection both in diltiazem (34%) and nitroglycerin groups (90%; P= 0.000, 0.000, respectively). CONCLUSIONS: Diltiazem infusion which started prior to harvesting provided higher IMA blood flow compared to nitroglycerin infusion. Considering the percentage of increases in flows after resection of distal segment, the most prone part to vasospasm, we assume that a certain amount of spasm occurred in IMA in spite of infusion of study drugs, such that less with diltiazem and more with nitroglycerin. Diltiazem plays more important role than nitroglycerin in the prevention of vasospasm.

Preemptive diclofenac reduces morphine use after remifentanil-based anaesthesia for tonsillectomy.

BACKGROUND: We investigated the effect of preincisional rectal diclofenac on pain scores and postoperative morphine requirements of children undergoing tonsillectomy after remifentanil-propofol anaesthesia in a randomized clinical trial. METHODS: Induction and maintenance of anaesthesia were with remifentanil and propofol. Forty children were randomly assigned into two groups before incision. The diclofenac group (n=20) received diclofenac suppositories (approximately 1 mg x kg(-1)) and the control group (n=20) received no treatment. Following discontinuation of remifentanil, patient-controlled analgesia (PCA) with morphine (a loading dose 50 micro g x kg(-1), a background infusion 4 micro g x kg(-1) x h(-1) and a demand dose 20 micro g x kg(-1) with 5-min intervals) was started. We assessed pain score [verbal analogue scales (VAS), 0-10] and sedation level at 5-min intervals and recorded the total morphine consumption of the first hour in the PACU. Patients were discharged to the ward with a new PCA morphine programme (a demand dose 20 micro g.kg-1 with a lockout time of 30 min, for 4 h), and total morphine consumption was recorded. RESULTS: The mean VAS score of the diclofenac group was significantly lower than the control group on arrival in the PACU (2.85 +/- 0.77, 7.60 +/- 0.83, respectively, P < 0.01) and it remained significantly lower in the PACU stay of the children. The mean total morphine consumption of the diclofenac group was less than the control group in the PACU (130.33 +/- 11.26 and 169.92 +/- 9.22, respectively, P=0.012) and the ward (50.80 +/- 11.38 and 87.77 +/- 10.55, respectively, P=0.021). CONCLUSIONS: Preemptive diclofenac given rectally reduced pain intensity and morphine requirements of children anaesthetized with remifentanil for tonsillectomy.