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Biomedical subjects

A C Webster

Publications and source records attributed to A C Webster.

At least 19 recordsLinked to original sources

Target of rapamycin inhibitors (TOR-I; sirolimus and everolimus) for primary immunosuppression in kidney transplant recipients.

BACKGROUND: Target of rapamycin inhibitors (TOR-I) (sirolimus, everolimus) are immunosuppressive agents with a novel mode of action but an uncertain clinical role. OBJECTIVES: To investigate the benefits and harms of immunosuppressive regimens containing TOR-I when compared to other regimens as initial therapy for kidney transplant recipients. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library, issue 2, 2005), MEDLINE (1966-June 2005), EMBASE (1980-June 2005), the specialised register of the Cochrane Renal Group (June 2005)., and contacted authors and pharmaceutical companies to identify relevant studies. SELECTION CRITERIA: All randomised controlled trials (RCTs) and quasi-RCTs where drug regimens containing TOR-I were compared to alternative drug regimens in the immediate post-transplant period were included, without age restriction, dosage or language of report. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trials for eligibility and quality, and extracted data. Results are expressed as relative risk (RR) or weight mean difference (MD) with 95% confidence intervals (CI). MAIN RESULTS: Thirty three trials (142 reports) were included (sirolimus (27), everolimus (5), head-to-head (1)). When TOR-I replaced CNI there was no difference in acute rejection, but serum creatinine was lower (MD -18.31 micromol/L, -30.96 to -5.67), and bone marrow more suppressed (leucopenia: RR 2.02 1.12 to 3.66; thrombocytopenia: RR 6.97 2.97 to 16.36; anaemia: RR 1.67, 1.27 to 2.20). When TOR-I replaced antimetabolites, acute rejection (RR 0.84, 0.71 to 0.99) and cytomegalovirus infection (CMV) (RR 0.49; 0.37 to 0.65) were reduced, but hypercholesterolaemia was increased (RR 1.65, 1.32 to 2.06). For low versus high-dose TOR-I, with equal CNI dose, rejection was increased (RR 1.23, 1.06 to 1.43) but calculated GFR higher (MD 4.27 mL/min, 1.12 to 7.41), and for low-dose TOR-I/standard-dose CNI versus higher-dose TOR-I/reduced CNI, acute rejection (RR 0.67, 0.52 to 0.88) and calculated GFR (MD -9.46 mL/min, -12.16 to -6.76) were reduced. There was no significant difference in mortality, graft loss or malignancy risk for TOR-I in any comparison. AUTHORS' CONCLUSIONS: TOR-I have been evaluated in four different primary immunosuppressive algorithms; as replacement for CNI and for antimetabolites, in combination with CNI at low and high dose and with variable dose of CNI. Generally, surrogate endpoints for graft survival favour TOR-I (lower risk of acute rejection and higher GFR) and surrogate endpoints for patient outcomes are worsened by TOR-I (bone marrow suppression, lipid disturbance). Long-term hard-endpoint data from methodologically robust RCTs are still needed.

Everolimus↗

Antifungal agents for preventing fungal infections in non-neutropenic critically ill patients.

BACKGROUND: Invasive fungal infections, important causes of morbidity and mortality in critically ill patients, may be preventable with the prophylactic administration of antifungal agents. OBJECTIVES: This study aims to systematically identify and summarize the effects of antifungal prophylaxis in non-neutropenic critically ill adult patients on all-cause mortality and the incidence of invasive fungal infections. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 3, 2005), MEDLINE (1966 to 2 September 2005), and EMBASE (1980 to week 36, 2005). We also handsearched reference lists, abstracts of conference proceedings and scientific meetings (1998 to 2004), and contacted authors of included studies and pharmaceutical manufacturers. SELECTION CRITERIA: We included randomized controlled trials in all languages comparing the prophylactic use of any antifungal agent or regimen with placebo, no antifungal, or another antifungal agent or regimen in non-neutropenic critically ill adult patients. DATA COLLECTION AND ANALYSIS: Two authors independently applied selection criteria, performed quality assessment, and extracted data using an intention-to-treat approach. We resolved differences by discussion. We synthesized data using the random effects model and expressed results as relative risk with 95% confidence intervals. MAIN RESULTS: We included 12 unique trials (eight comparing fluconazole and four ketoconazole with no antifungal or a nonabsorbable agent) involving 1606 randomized patients. For both outcomes of total mortality and invasive fungal infections, almost all trials of fluconazole and ketoconazole separately showed a non-significant risk reduction with prophylaxis. When combined, fluconazole/ketoconazole reduced total mortality by about 25% (relative risk 0.76, 95% confidence interval 0.59 to 0.97) and invasive fungal infections by about 50% (relative risk 0.46, 95% confidence interval 0.31 to 0.68). We identified no significant increase in the incidence of infection or colonization with the azole-resistant fungal pathogens Candida glabrata or C. krusei, although the confidence intervals of the summary effect measures were wide. Adverse effects were not more common amongst patients receiving prophylaxis. Results across all trials were homogeneous despite considerable heterogeneity in clinical and methodological characteristics. AUTHORS' CONCLUSIONS: Prophylaxis with fluconazole or ketoconazole in critically ill patients reduces invasive fungal infections by one half and total mortality by one quarter. Although no significant increase in azole-resistant Candida species associated with prophylaxis was demonstrated, trials were not powered to exclude such an effect. In patients at increased risk of invasive fungal infections, antifungal prophylaxis with fluconazole should be considered.

Adult↗

Systematic review and meta-analysis of antifungal agents for preventing fungal infections in liver transplant recipients.

A systematic review and meta-analysis was performed to evaluate the benefits and harms of antifungal prophylaxis in liver transplant recipients. Ten randomised trials comparing any prophylactic antifungal regimen with no antifungal agent or with another antifungal regimen were identified from Medline, EMBASE, the Cochrane Library, and other sources. Together, the studies included a total of 1,106 patients. In general, results were consistent across trials despite clinical and methodological heterogeneity. Antifungal prophylaxis did not reduce total mortality (RR 0.84, 95% CI: 0.54-1.3). Fluconazole prophylaxis reduced invasive fungal infections by about 75% (RR 0.28, 95% CI: 0.13-0.57). Although fewer data on prophylactic itraconazole and liposomal amphotericin B were available, indirect comparisons and three direct comparative trials suggested similar efficacy. Fluconazole prophylaxis did not significantly increase colonisation or infection with azole-resistant fungi, although data were limited. A subgroup analysis suggested a dose and duration effect. In conclusion, fluconazole prophylaxis significantly reduces invasive fungal infections in liver transplant recipients and should be instituted in patients at increased risk in the early postoperative period.

Antifungal Agents↗

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients.

BACKGROUND: The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis with the aim of preventing the clinical syndrome associated with CMV infection. OBJECTIVES: To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause mortality in solid organ transplant recipients. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, reference lists and abstracts from conference proceedings without language restriction. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing antiviral medications with placebo or no treatment, trials comparing different antiviral medications and trials comparing different regimens of the same antiviral medications in recipients of any solid organ transplant. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data from each trial. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) for dichotomous outcomes with 95% confidence intervals (CI). Subgroup analysis and univariate meta-regression were performed using restricted maximum-likelihood to estimate the between study variance. Multivariate meta-regression was performed to investigate whether the results were altered after allowing for differences in drugs used, organ transplanted and recipient CMV serostatus at the time of transplantation. MAIN RESULTS: Thirty two trials (3737 participants) were identified. Prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment significantly reduced the risk for CMV disease (19 trials; RR 0.42, 95% CI 0.34 to 0.52), CMV infection (17 trials; RR 0.61, 95% CI 0.48 to 0.77), and all-cause mortality (17 trials; RR 0.63, 95% CI 0.43 to 0.92) primarily due to reduced mortality from CMV disease (seven trials; RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduced the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but not fungal infection, acute rejection or graft loss. Meta-regression showed no significant difference in the risk of CMV disease or all-cause mortality by organ transplanted or CMV serostatus; no conclusions were possible for CMV negative recipients of negative organs. In direct comparison trials, ganciclovir was more effective than aciclovir in preventing CMV disease (seven trials; RR 0.37, 95% Cl 0.23 to 0.60). Valganciclovir and intravenous ganciclovir were as effective as oral ganciclovir. AUTHORS' CONCLUSIONS: Prophylaxis with antiviral medications reduces CMV disease and CMV-associated mortality in solid organ transplant recipients. They should be used routinely in CMV positive recipients and in CMV negative recipients of CMV positive organ transplants.

Acyclovir↗

Interleukin 2 receptor antagonists for kidney transplant recipients.

BACKGROUND: Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily, with 38% of new kidney transplant recipients in the United States, and 23% in Australasia receiving IL2Ra in 2002. OBJECTIVES: This study aims to systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to other antibody therapy. SEARCH STRATEGY: The Cochrane Renal Group's specialised register (June 2003), the Cochrane Controlled Trials Register (in The Cochrane Library issue 3, 2002), MEDLINE (1966-November 2002) and EMBASE (1980-November 2002). Reference lists and abstracts of conference proceedings and scientific meetings were hand-searched from 1998-2003. Trial groups, authors of included reports and drug manufacturers were contacted. SELECTION CRITERIA: Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy. DATA COLLECTION AND ANALYSIS: Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) with 95% confidence intervals (CI). MAIN RESULTS: One hundred and seventeen reports from 38 trials involving 4893 participants were included. Where IL2Ra were compared with placebo (17 trials; 2786 patients), graft loss was not significantly different at one (RR 0.83, 95% CI 0.66 to 1.04) or three years (RR 0.88, 95% CI 0.64 to 1.22). Acute rejection (AR) was significantly reduced at six months (RR 0.66, 95% CI 0.59 to 0.74) and at one year (RR 0.67, 95% CI 0.60 to 0.75). At one year, cytomegalovirus (CMV) infection (RR 0.82, 95% CI 0.65 to 1.03) and malignancy (RR 0.67, 95% CI 0.33 to 1.36) were not significantly different. Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra. REVIEWER'S CONCLUSIONS: Given a 40% risk of rejection, seven patients would need treatment with IL2Ra to prevent one patient having rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects

Graft Rejection↗

Antifungal agents for preventing fungal infections in solid organ transplant recipients.

BACKGROUND: Invasive fungal infections (IFIs) are important causes of morbidity and mortality in solid organ transplant recipients. OBJECTIVES: This study aims to systematically identify and summarise the effects of antifungal prophylaxis in solid organ transplant recipients. SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (Issue 3, 2003), MEDLINE (1966-June 2003), and EMBASE (1980-June 2003) were searched. Reference lists, abstracts of conference proceedings and scientific meetings (1998-2003) were handsearched. Authors of included studies and pharmaceutical manufacturers were contacted. SELECTION CRITERIA: Randomised controlled trials (RCTs) in all languages comparing the prophylactic use of any antifungal agent or regimen with placebo, no antifungal, or another antifungal agent or regimen. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied selection criteria, performed quality assessment, and extracted data using an intention-to-treat approach. Differences were resolved by discussion. Data were synthesised using the random effects model and expressed as relative risk (RR) with 95% confidence intervals (95% CI). MAIN RESULTS: Fourteen unique trials with 1497 randomised participants were included. Antifungal prophylaxis did not reduce mortality (RR 0.90, 95% CI 0.57 to 1.44). In liver transplant recipients, a significant reduction in IFIs was demonstrated for fluconazole (RR 0.28, 95% CI 0.13 to 0.57). Although less data were available for itraconazole and liposomal amphotericin B, indirect comparisons and one direct comparative trial suggested similar efficacy. Fluconazole prophylaxis did not significantly increase invasive infections or colonisation with fluconazole-resistant fungi. In renal and cardiac transplant recipients, neither ketoconazole nor clotrimazole significantly reduced invasive infections. Overall, the strength and precision of comparisons however were limited by a paucity of data. REVIEWERS' CONCLUSIONS: For liver transplant recipients, antifungal prophylaxis with fluconazole significantly reduces the incidence of IFIs with no definite mortality benefit. Given a 10% incidence of IFI, 14 liver transplant recipients would require fluconazole prophylaxis to prevent one infection. In transplant centres where the incidence of IFIs is high, or in situations where the individual risk is great, antifungal prophylaxis should be considered.

Antifungal Agents↗

Cloning and characterization of vuuA, a gene encoding the Vibrio vulnificus ferric vulnibactin receptor.

The ability of Vibrio vulnificus to acquire iron from the host has been shown to correlate with virulence. Many iron transport genes are regulated by iron, and in V. vulnificus, transcriptional regulation by iron depends on the fur gene. The N-terminal amino acid sequence of a 72-kDa iron-regulated outer membrane protein purified from a V. vulnificus fur mutant had 53% homology with the first 15 amino acids of the mature protein of the Vibrio cholerae vibriobactin receptor, ViuA. In this report, we describe the cloning, DNA sequence, mutagenesis, and analysis of transcriptional regulation of the structural gene for VuuA, the vulnibactin receptor of V. vulnificus. Analysis of the DNA sequence of the vuuA promoter region demonstrated a sequence identical to the upstream Fur box of V. cholerae viuA. Northern blot analysis showed that the transcript was strongly regulated by iron. The amino acid sequence of VuuA was 74% identical to the sequence of V. cholerae ViuA and was homologous to those of several TonB-dependent outer membrane receptors. An internal deletion of the V. vulnificus vuuA gene resulted in the loss of expression of the 72-kDa protein and the loss of the ability to use transferrin or vulnibactin as a source of iron. This mutant showed reduced virulence in an infant mouse model. Introduction of a plasmid containing the complete viuA coding sequence and 342 bp of upstream DNA into the mutant restored ferric vulnibactin and ferric transferrin utilization to the mutant.

Amides↗

Anesthesia for intranasal surgery: a comparison between tracheal intubation and the flexible reinforced laryngeal mask airway.

UNLABELLED: The purpose of the study was to assess the suitability and safety of the flexible reinforced laryngeal mask airway (FRLMA) for intranasal surgery (INS) anesthesia. A secondary objective was to compare the incidence of complications of removal of the FRLMA with tracheal extubation in awake and anesthetized patients. One hundred fourteen ASA physical status I and II patients requiring INS were randomly assigned into three groups: Group I = FRLMA, Group II = endotracheal tube (ET) extubated awake, and Group II = ET extubated deeply anesthetized. In Group I, the incidence of coughing and oxyhemoglobin desaturation at removal was significantly reduced compared with that in Groups II and III (P < 0.05). There were no episodes of postremoval laryngospasm in Group I; in Group III, the incidence was 19% (P < 0.05), whereas in Group II, it was 6% (not significantly different). The number of patients with oxyhemoglobin desaturation < or = 92% on admission to the postanesthesia care unit was 0% in Group I, 26% in Group II (P < 0.05), and 16% in Group III (not significantly different). At bronchoscopy, the incidence of blood visible in the airway was low and similar among the three groups (3%, 6%, and 3%, respectively). There were no significant differences in the incidence of airway complications between Groups II and III. IMPLICATIONS: We compared airway management for intranasal surgery anesthesia using a new device, the flexible reinforced laryngeal mask airway, with the current standard of tracheal intubation. The study demonstrates that the flexible reinforced laryngeal mask airway can provide a safe, protected airway with a smoother emergence from anesthesia than tracheal intubation.

Adult↗

Laryngeal mask airway in paediatric otolaryngologic surgery.

The laryngeal mask airway (LMA) is a relatively recent development that fills the gap in airway management between endotracheal intubation and the use of a face mask. The device is inserted blindly into the pharynx, forming a low-pressure seal around the laryngeal inlet permitting gentle positive-pressure ventilation. It allows the administration of inhaled anaesthetic agents through a minimally stimulating airway. This factor, combined with its ease of insertion, suggested that the laryngeal mask airway might offer some distinct advantages in otolaryngologic paediatric surgery. Our experience in utilizing the laryngeal mask in tonsillectomy and adenoidectomy, and in myringotomies with insertion of ventilating tubes is described, and its advantages and disadvantages are discussed.

Adenoidectomy↗

Anaesthesia for adenotonsillectomy: a comparison between tracheal intubation and the armoured laryngeal mask airway.

A prototype armoured laryngeal mask airway (LMA) was compared with tracheal intubation (ETT) for anaesthesia for adenotonsillectomy. Fifty-five children were randomised into the LMA group and 54 into the ETT group. During insertion of the LMA, peripheral oxyhaemoglobin desaturation (SpO2) < 94% occurred in ten patients (18.2%) and in seven patients (13%) during tracheal intubation (NS). After opening the Boyle-Davis gag, airway obstruction occurred in ten patients (18.2%) in the LMA group and in three patients (6%) in the ETT group (P = 0.07). In five patients (9%) the LMA was abandoned in favour of tracheal intubation. In all others (91%), when the need for adequate depth of anaesthesia was realized, a satisfactory airway was achieved more rapidly than with tracheal intubation (P < 0.001), and maintained throughout surgery. Manually assisted ventilation was required in all patients in the ETT group, mean duration 373 +/- 385 sec, and in 26 patients (52%) in the LMA group, mean duration 134 +/- 110 sec, P < 0.001. Mean end-tidal CO2 (PetCO2) was 45.5 +/- 6.21 mmHg in the ETT group and 46.6 +/- 6.09 in the LMA group (NS). The LMA did not limit surgical access. Heart rate, MAP and blood loss in the LMA group were 110 +/- 21, 74 +/- 9 mmHg and 1.92 +/- 1.22 ml.kg-1 respectively, compared with 143 +/- 13 (P < 0.001), 85 +/- 12 mmHg (P < 0.001) and 2.62 +/- 1.36 ml.kg-1 (P < 0.05) with tracheal intubation. Fibreoptic laryngoscopy at the end of surgery in 19 patients in the LMA group revealed no blood in the larynx.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoidectomy↗

Lumbar epidural anaesthesia for inguinal hernia repair in low birth weight infants.

In view of the complications of general, spinal, and caudal anaesthesia for inguinal hernia repair in high-risk neonates, an evaluation of lumbar epidural anaesthesia (LEA) was undertaken to assess its technical feasibility, effectiveness and incidence of complications. In 18 consecutive cases, gestational age 26 +/- 2.6 wk, birth weight 877 +/- 310 g, 16 (89%) had bronchopulmonary dysplasia and 12 (67%) were oxygen-dependent at the time of surgery. Using a standard loss of resistance technique and a 4.0 cm 20 G epidural needle, the epidural space was positively identified on the first attempt in 16 (89%), and on the second attempt in 2 patients (11%). Reflux of 0.9% saline used to identify the epidural space was blood tinged in two cases. Epidural analgesia was achieved in all cases with bupivacaine 0.25% with and without 1:200,000 epinephrine, 0.75 ml.kg-1 for the first two cases, and subsequently 1.0 ml.kg-1. In 15 patients (83%), good operating conditions were achieved with epidural analgesia alone. Inhalational anaesthesia supplementation was necessary in three cases (17%). In the first two patients, the level of analgesia (T8) was insufficient to control the response to traction on the hernial sac. In one infant, analgesic to T4, whose surgery was inadvertently delayed for four hours, inhalation anaesthesia was needed to control restlessness rather than pain. Ten infants were analgesic to T2, four to T4, two to T6 and two to T8. Intraoperative periodic breathing was seen in seven infants (39%), four with oxyhaemoglobin desaturation to 75%, and two to 85%. All responded to increased FIO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia, Epidural↗

Spinal anaesthesia for inguinal hernia repair in high-risk neonates.

To avoid the high incidence of respiratory complications associated with general anaesthesia in premature neonates, 44 spinal anaesthetics for inguinal hernia repair in very low birthweight infants were administered in 47 attempts. Hyperbaric tetracaine with epinephrine 1:200,000 was administered in a dose range of 0.27-1.10 mg.kg-1. Attempted lumbar puncture failed in three infants. In 24 procedures, spinal anaesthesia alone provided satisfactory operating conditions; in 20, supplementary inhalational general anaesthesia or iv ketamine was necessary. Perioperative apnoeic episodes requiring bag/mask assisted ventilation occurred in six infants. In five infants, apnoeic spells occurred in the postoperative period. No infant required tracheal intubation; there was no haemodynamic instability. Twenty-four infants required no postoperative analgesia. Our experience suggests that spinal anaesthesia for inguinal hernia repair in very low birth weight infants reduces but does not eliminate the risk of respiratory instability, and that supplementary anaesthesia is often necessary to provide satisfactory operating conditions.

Anesthesia, Inhalation↗

Regional blood flow change in the lamb during the perinatal period.

Regional blood flow distribution was studied with a radioactive-labeled microsphere technique in 11 unanesthetized fetal sheep (139 to 143 days' gestation). After cesarean delivery each neonatal lamb was studied at 2 and 24 hours of age. Blood flow to the cerebral hemispheres and adrenal glands decreased progressively after birth and correlated inversely with the postnatal rise in arterial oxygen content (r = -0.77, p less than 0.001 and r = -0.52, p less than 0.01, respectively). Blood flow to the gastrointestinal tract and kidneys changed little despite the known increase in blood flow from the late fetal to the early neonatal period. Skeletal muscle and brown fat blood flow were both increased when measured at 2 hours after birth, with an even greater increase in their respective oxygen deliveries presumably reflecting their increased metabolic activity with thermogenesis at this time. Variable blood flow changes are thus evident over the immediate perinatal period. In some cases these changes reflect birth-related changes in either blood gases or functional activity whereas in others the changes simply reflect a continuum from the late fetal to the early neonatal period.

Animals↗

Haemodynamic effects of induction of epidural analgesia in labour.

The effect of induction of epidural analgesia with 0.5 per cent bupivacaine on maternal haemodynamics was investigated in 21 patients with uncomplicated full-term pregnancies in early labour. Stroke volume, heart rate, and cardiac output (SV, HR, and CO) were measured by transcutaneous aortovelography (TAV). Systolic, diastolic, and mean arterial blood pressures (SBP, DNP, and MAP) were measured by indirect automatic oscillometry. Measurements were made with the patient in the left lateral decubitus position before and after an intravenous bolus of 500 ml of lactated Ringer's solution preceding induction of epidural analgesia, and again 30 and 45 minutes after induction. The 500 ml bolus of lactated Ringer's solution did not prevent fall of CO and BP measured 30 minutes after induction, when there were statistically significant decreases in CO and cardiac index (-10.2 and -10.6 per cent, p less than 0.05), and in SBP, DBP, and MAP (-9.7, -12.5, and -11.9 per cent, p less than 0.005, p less than 0.005 and p less than 0.01 respectively). At 45 minutes after induction, CO and cardiac index had returned to baseline values. Although the decreases in SDP and DBP persisted, the change in MAP was not statistically significant.

Adult↗