Microsynt: exploring the syntax of EEG microstates

Microstates represent electroencephalographic (EEG) activity as a sequence of switching, transient, metastable states. Growing evidence suggests the useful information on brain states is to be found in the higher-order temporal structure of these sequences. Instead of focusing on transition probabilities, here we propose "Microsynt", a method designed to highlight higher-order interactions that form a preliminary step towards understanding the syntax of microstate sequences of any length and complexity. Microsynt extracts an optimal vocabulary of "words" based on the length and complexity of the full sequence of microstates. Words are then sorted into classes of entropy and their representativeness within each class is statistically compared with surrogate and theoretical vocabularies. We applied the method on EEG data previously collected from healthy subjects undergoing propofol anaesthesia, and compared their "fully awake" (BASE) and "fully unconscious" (DEEP) conditions. Results show that microstate sequences, even at rest, are not random but tend to behave in a more predictable way, favoring simpler sub-sequences, or "words". Contrary to high-entropy words, lowest-entropy binary microstate loops are prominent and favored on average 10 times more than what is theoretically expected. Progressing from BASE to DEEP, the representation of low-entropy words increases while that of high-entropy words decreases. During the awake state, sequences of microstates tend to be attracted towards "A - B - C" microstate hubs, and most prominently A - B binary loops. Conversely, with full unconsciousness, sequences of microstates are attracted towards "C - D - E" hubs, and most prominently C - E binary loops, confirming the putative relation of microstates A and B to externally-oriented cognitive processes and microstate C and E to internally-generated mental activity. Microsynt can form a syntactic signature of microstate sequences that can be used to reliably differentiate two or more conditions.

Reviewing next of kin regrets in surgical decision-making: cross-sectional analysis of systematically searched literature

BACKGROUND

Decision-making concerning relatives undergoing surgery is challenging. It remains unclear to what extent implicated next of kin eventually regret their decisions and how this regret is assessed. Our aim was to systematically review the literature on decisional regret of next of kin and to describe the assessment tools used and the surgical populations studied.

METHODS

We included interventional or observational, quantitative or qualitative studies reporting the measurement of decisional regret of next of kin concerning relatives undergoing surgery. We searched a variety of databases without restriction on publication year. We assessed the quality of reporting of quantitative studies using the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies and of qualitative studies using the Critical Appraisal Skills Program Checklist.

RESULTS

Thirteen cross-sectional, five prospective cohorts and five qualitative studies matched our inclusion criteria. In 18 studies (78%), patients were children, in five (22%), young or middle-aged adults. No study included elderly or frail patients. Thirteen studies (57%) used the original Decision Regret Scale which was validated for patients, but not for next of kin. Only 3 of the 18 (17%) quantitative studies and only one of the 4 (25%) qualitative studies were rated as "good" in the quality assessment.

CONCLUSION

None of the retrieved studies used validated tools to assess the decisional regret of next of kin and none of them examined this issue in elderly or frail surgical patients.

EEG microstate dynamics indicate a U-shaped path to propofol-induced loss of consciousness

Evidence suggests that the stream of consciousness is parsed into transient brain states manifesting themselves as discrete spatiotemporal patterns of global neuronal activity. Electroencephalographical (EEG) microstates are proposed as the neurophysiological correlates of these transiently stable brain states that last for fractions of seconds. To further understand the link between EEG microstate dynamics and consciousness, we continuously recorded high-density EEG in 23 surgical patients from their awake state to unconsciousness, induced by step-wise increasing concentrations of the intravenous anesthetic propofol. Besides the conventional parameters of microstate dynamics, we introduce a new implementation of a method to estimate the complexity of microstate sequences. The brain activity under the surgical anesthesia showed a decreased sequence complexity of the stereotypical microstates, which became sparser and longer-lasting. However, we observed an initial increase in microstates' temporal dynamics and complexity with increasing depth of sedation leading to a distinctive "U-shape" that may be linked to the paradoxical excitation induced by moderate levels of propofol. Our results support the idea that the brain is in a metastable state under normal conditions, balancing between order and chaos in order to flexibly switch from one state to another. The temporal dynamics of EEG microstates indicate changes of this critical balance between stability and transition that lead to altered states of consciousness.

Genetic Susceptibility Toward Nausea and Vomiting in Surgical Patients

Postoperative nausea and vomiting (PONV) are frequently occurring adverse effects following surgical procedures. Despite predictive risk scores and a pallet of prophylactic antiemetic treatments, it is still estimated to affect around 30% of the patients, reducing their well-being and increasing the burden of post-operative care. The aim of the current study was to characterize selected genetic risk factors of PONV to improve the identification of at risk patients. We genotyped 601 patients followed during the first 24 h after surgery for PONV symptoms in the absence of any antiemetic prophylaxis. These patients were recruited in the frame of a randomized, placebo controlled clinical study aiming to test the efficacy of dexamethasone as a treatment of established PONV. We examined the impact of selected single nucleotide polymorphisms (SNPs) located around 13 different genes and the predicted activity of 6 liver drug metabolizing enzymes from the cytochromes P450 family (CYP) on the occurrence and recurrence of PONV. Our genetic study confirms the importance of genetic variations in the type 3B serotonin receptor in the occurrence of PONV. Our modelling shows that integration of rs3782025 genotype in preoperative risk assessments may help improve the targeting of antiemetic prophylaxis towards patients at risk of PONV.

Rapid Sequence Induction With a Standard Intubation Dose of Rocuronium After Magnesium Pretreatment Compared With Succinylcholine: A Randomized Clinical Trial

BACKGROUND

Succinylcholine remains the muscle relaxant of choice for rapid sequence induction (RSI) but has many adverse effects. High-dose rocuronium bromide may be an alternative to succinylcholine for RSI but recovery times are nearly doubled compared with a standard intubating dose of rocuronium. Magnesium sulfate significantly shortens the onset time of a standard intubating dose of rocuronium. We set out to investigate whether intravenous (IV) pretreatment with MgSO4 followed by a standard intubating dose of rocuronium achieved superior intubation conditions compared with succinylcholine.

METHODS

Adults were randomized to receive a 15-minute IV infusion of MgSO4 (60 mg·kg-1) immediately before RSI with propofol 2 mg·kg-1, sufentanil 0.2 μg·kg-1 and rocuronium 0.6 mg·kg-1, or a matching 15-minute IV infusion of saline immediately before an identical RSI, but with succinylcholine 1 mg·kg-1. Primary end point was the rate of excellent intubating conditions 60 seconds after administration of the neuromuscular blocking agent and compared between groups using multivariable log-binomial regression model. Secondary end points were blood pressure and heart rate before induction, before and after intubation, and adverse events up to 24 hours postoperatively.

RESULTS

Among 280 randomized patients, intubating conditions could be analyzed in 259 (133 MgSO4-rocuronium and 126 saline-succinylcholine). The rate of excellent intubating conditions was 46% with MgSO4-rocuronium and 45% with saline-succinylcholine. The analysis adjusted for gender and center showed no superiority of MgSO4-rocuronium compared with saline-succinylcholine (relative risk [RR] 1.06, 95% confidence interval [CI], 0.81-1.39, P = .659). The rate of excellent intubating conditions was higher in women (54% [70 of 130]) compared with men (37% [48 of 129]; adjusted RR 1.42, 95% CI, 1.07-1.91, P = .017). No significant difference between groups was observed for systolic and diastolic blood pressures. Mean heart rate was significantly higher in the MgSO4-rocuronium group. The percentage of patients with at least 1 adverse event was lower with MgSO4-rocuronium (11%) compared with saline-succinylcholine (28%) (RR 0.38, 95% CI, 0.22-0.66, P < .001). With saline-succinylcholine, adverse events consisted mainly of postoperative muscle pain (n = 26 [19%]) and signs of histamine release (n = 13 [9%]). With MgSO4-rocuronium, few patients had pain on injection, nausea and vomiting, or skin rash during the MgSO4-infusion (n = 5 [4%]).

CONCLUSIONS

IV pretreatment with MgSO4 followed by a standard intubating dose of rocuronium did not provide superior intubation conditions to succinylcholine but had fewer adverse effects.

The optimal dose of succinylcholine for rapid sequence induction: a systematic review and meta-analysis of randomized trials

Background

The evidence base for the widely accepted standard regimen of succinylcholine for rapid sequence induction (1.0 mg kg^− 1) remains unclear.

Methods

We performed a systematic review and meta-analysis of randomized trials comparing any succinylcholine regimen with the standard regimen (1.0 mg kg^− 1) and reporting on intubating conditions and/or apnoea times. Results were expressed as absolute risk differences (ARD) for dichotomous data and mean differences (MD) for continuous data.

Results

We retrieved six trials with relevant data of 864 patients (ASA 1 or 2, aged 18–65 years, body mass index < 30 kg m^− 2). Four regimens (0.3, 0.4, 0.5, 0.6 mg kg^− 1) were compared with 1.0 mg kg^− 1 in at least three trials each, and three (0.8, 1.5, 2 mg kg^− 1) in one each. With 0.3 to 0.5 mg kg^− 1, the likelihood of excellent intubating conditions was significantly decreased (ARD − 22% to − 67%). With 0.3 and 0.4 mg kg^− 1, but not with 0.5, 0.6, 0.8, 1.5 and 2.0 mg kg^− 1, the likelihood of unacceptable intubating conditions was significantly increased (ARD + 22% and + 32%, respectively). With 2.0 mg kg^− 1, but not with 0.8 or 1.5 mg kg^− 1, the likelihood of excellent intubating conditions was significantly increased (ARD + 23%). Apnoea times were significantly shorter with regimens ≤0.8 mg kg^− 1 (MD − 1.0 to − 3.4 min) but were not reported with 1.5 or 2.0 mg kg^− 1.

Conclusions

With succinylcholine regimens ≤0.5 mg kg^− 1, excellent intubating conditions are less likely and apnoea times are shorter, compared with 1 mg kg^− 1. With 0.3 and 0.4 mg kg^− 1, unacceptable intubating conditions are more common. Succinylcholine 1.5 mg kg^− 1 does not produce more often excellent conditions compared with 1 mg kg^− 1, while 2.0 mg kg^− 1 does, but the database with these regimens is weak and apnoea times remain unknown. Limited information size and strong statistical heterogeneity decrease the certainty of the evidence.

Assessment of spontaneous neuromuscular recovery: A comparison of the TOF-Cuff® with the TOF Watch SX®

BACKGROUND

TOF-Cuff^® is a modified blood pressure cuff used to monitor neuromuscular block. We compared the assessment of spontaneous neuromuscular recovery between TOF-Cuff^® (test device) and TOF Watch SX^® (reference device).

METHODS

Forty patients aged 18-65 years undergoing elective surgery were enrolled. TOF-Cuff^® was installed on an upper arm and the TOF Watch SX^® on the thumb of the opposite side. Anaesthesia was induced and maintained with intravenous propofol and sufentanil. After induction, the devices were calibrated and continuous train-of-four (TOF) stimulation was started. A single intravenous dose of rocuronium (0.6 mg kg^-1 ) was administered for intubation. The primary outcome was total recovery time (time in minutes from the injection of rocuronium to a normalized TOF ratio of 90%). Agreement between the two devices was calculated using mean difference and limits of agreement.

RESULTS

The primary outcome could be analysed in 27 patients because of 13 exclusions due to neuromuscular block reversal for shorter procedure surgical time, necessity of reinjection of rocuronium or technical failures of one of the two devices. Median total recovery time with the test device was 45 minutes (interquartile range [IQR] 38.5-61.5) and 63 minutes (IQR 51.1-74.5) with the reference device. Total recovery time with the test device was on average 16.4 minutes shorter (limits of agreement, -6.1 to 39); increasing total recovery time was associated with increasing difference. The TOF ratio of the reference device was on average 0.59 (SD 0.23) when the test device indicated complete recovery. The TOF ratio of the test device was on average 0.98 (SD 0.03) when the reference device indicated complete recovery.

CONCLUSION

When compared with the TOF Watch SX^® , TOF-Cuff^® overestimates spontaneous recovery of a rocuronium-induced neuromuscular block.

Patient-Controlled Versus Clinician-Controlled Sedation With Propofol: Systematic Review and Meta-analysis With Trial Sequential Analyses

BACKGROUND

Sedation with propofol is frequently used to facilitate diagnostic and therapeutic procedures. Propofol can be administrated by the patient (patient-controlled sedation [PCS]) or by a clinician (clinician-controlled sedation [CCS]). We aimed to compare these 2 techniques.

METHODS

PubMed, Embase, CENTRAL, and trial registries were searched up to October 2017 for randomized controlled trials comparing PCS with CCS with propofol. The primary end points were the risks of presenting at least 1 episode of oxygen desaturation, arterial hypotension, and bradycardia, and the risk of requiring a rescue intervention (pharmacologic therapies or physical maneuvers) for sedation-related adverse events. Secondary end points were the dose of propofol administrated, operator and patient satisfaction, and the risk of oversedation. A random-effects model and an α level of .02 to adjust for multiple analyses were used throughout. Trial sequential analyses were performed for primary outcomes. Quality of evidence was assessed according to the Grades of Recommendation, Assessment, Development, and Evaluation system.

RESULTS

Thirteen trials (1103 patients; median age, 47 years; American Society of Anesthesiologists physical status I-III) describing various diagnostic and therapeutic procedures with propofol sedation were included. PCS had no impact on the risk of oxygen desaturation (11 trials, 31/448 patients [6.9%] with PCS versus 46/481 [9.6%] with CCS; risk ratio, 0.74 [98% confidence interval, 0.35-1.56]) but decreased the risk of requiring a rescue intervention for adverse events (11 trials, 29/449 patients [6.5%] with PCS versus 74/482 [15.4%] with CCS; risk ratio, 0.45 [98% confidence interval, 0.25-0.81]). For both outcomes, Trial sequential analyses suggested that further trials were unlikely to change the results, although the quality of evidence was graded very low for all primary outcomes. For the risk of arterial hypotension and bradycardia, the required sample size for a definitive conclusion had not been reached. Analysis of secondary outcomes suggested that PCS decreased the risk of oversedation and had no impact on propofol dose administrated, or on operator or patient satisfaction.

CONCLUSIONS

PCS with propofol, compared with CCS with propofol, had no impact on the risk of oxygen desaturation, but significantly decreased the risk of rescue interventions for sedation-related adverse events. Further high-quality trials are required to assess the risks and benefits of PCS.

Reporting of conflicts of interest and of sponsorship of guidelines in anaesthesiology. A cross-sectional study

Guideline recommendations may be biased due to conflicts of interest (COI) of panel members and sponsorship of the guideline. Potential impact of COI, and their management, should be transparently reported. We analysed 110 guidelines published in ten anaesthesia journals from 2007 to June 2018. We report on the number (%) that 1) published COI disclosures; 2) in a distinct paragraph; 3) described and explained the COI of panel members, and 4) of the Chairperson; 5) reported and described the presence or absence and potential impact of a sponsor of the guideline on the recommendations; and 6) reported how COI were managed. COI were published in 70/110 (64%) guidelines; in a distinct paragraph in 25/70 (36%). Panel members reported having no COI in 27/70 (39%) guidelines, disclosed COI without describing their potential impact in 41/70 (59%), and described their potential impact in 2/70 (3%). Chairpersons were identified in 50 guidelines, 32 of which published COI disclosures; 16/32 (50%) reported having no COI, 14/32 (44%) disclosed COI without describing their potential impact, 1/32 (3%) described their impact and 1/32 (3%) made no statement regarding COI. Presence or absence of a sponsor of the guideline was reported in 40 guidelines; 12/40 (30%) declared none, 24/40 (60%) reported sponsoring without explanation of the potential impact, and 4/40 (10%) described the potential influence of the sponsor on the guideline recommendations. Seventy-five guidelines reported COI of panel members and/or sponsorship of the guideline but only seven described how the COI had been managed. Disclosures of COI of panel members and of sponsors of guidelines have increased over the 12 year period, but remain insufficiently described and their potential influence on the guidelines' recommendations is poorly documented.

Identification of ethics committees based on authors' disclosures: cross-sectional study of articles published in the European Journal of Anaesthesiology and a survey of ethics committees

Background

Since 2010, the European Journal of Anaesthesiology has required the reporting of five items concerning ethical approval in articles describing human research: ethics committee’s name and address, chairperson’s name, study’s protocol number and approval date. We aimed to assess whether this requirement has helped to identify and to contact the referenced ethics committees.

Methods

In this cross-sectional study, we analysed articles requiring ethical approval, according to the Swiss federal law for human research and published in the European Journal of Anaesthesiology in 2011. Ethics committees were searched through our institutional Internet access based on information provided in the articles. The last search was performed in November 2015. Numbers (%) of items reported, of ethics committees identified, and of those that confirmed having provided ethical approval are reported.

Results

Of 76 articles requiring ethical approval, 74 (97%) declared it. Ethics committees’ names and addresses were mentioned in 63/74 (85%), protocol numbers in 51/74 (69%), approval dates in 48/74 (65%), and chairpersons’ names in 45/74 (61%). We could identify 44/74 (59%) committees; 36/74 (49%) answered our inquiry and 24/74 (32%) confirmed their role. Thirty-four of 74 articles (46%) reported all five items; in 25/34 (74%), we were able to identify an ethics committee, 18/34 (53%) answered our inquiry, and 15/34 (44%) confirmed their role. Forty of 74 articles (54%) reported ≤4 items; in 19/40 (48%), we were able to identify an ethics committee, 18/40 (45%) answered our inquiry, and 9/40 (23%) confirmed their role. Reporting five items significantly increased identification of ethics committees (p = 0.023) and their confirmation of ethical approval (p = 0.048). Twelve of 74 ethics committees (16%) were unable to confirm their role in approving the study.

Conclusions

Even when details concerning ethical approval were reported in these studies of human research, we were unable to identify almost half of the ethics committees concerned. The reporting of five items, compared with reporting ≤4, was associated with facilitated identification of ethics committees, and increased the likelihood that they would be able to confirm the study’s approval. Future research should identify which information facilitates identification of, and contact with, ethics committees.

Electronic supplementary material

The online version of this article (10.1186/s12910-018-0289-y) contains supplementary material, which is available to authorized users.

Effect of sufentanil on bispectral index in the elderly

We examined the impact of adding sufentanil during anaesthesia induction with propofol on bispectral index values in elderly patients (≥ 65 years). Patients were randomly assigned to receive a target-controlled sufentanil infusion (effect-site concentration of 0.3 ng.ml^-1 ) or matching placebo, followed by a target-controlled propofol induction (initial effect-site concentration of 0.5 μg.ml^-1 ; step-wise increase of 0.5 μg.ml^-1 ) until loss of consciousness defined as an Observer's Assessment of Alertness/Sedation score < 2. Seventy-one patients (sufentanil 35, placebo 36) completed the study. Mean (SD) age was 72.3 (5.8) years; 41% were women. At loss of consciousness, mean (SD) bispectral index value was 75.0 (8.6) with sufentanil and 70.0 (8.0) with placebo; mean difference -5.0 (95% confidence interval -8.9 to -1.1), p = 0.013. Post-hoc analyses suggest that the difference was significant in men only (mean difference -7.3 (-11.8 to -2.6), p = 0.003). Sufentanil co-induction with propofol results in higher bispectral index values at loss of consciousness in elderly patients.

Contraction response to muscle percussion: A reappraisal of the mechanism of this bedside test

OBJECTIVE

To study whether the contraction evoked by muscle percussion stems from the excitation of the muscle or of the nerve and to discuss the changes of this response in neuromuscular disorders.

METHODS

In 30 neurologically healthy patients undergoing surgery (for ear, nose, or throat problems unrelated to the study) under general anesthesia with propofol and sufentanil we measured with an electrogoniometer the maximal dorsiflexion of the ankle evoked by reflex hammer percussion of the tibialis anterior muscle before and under neuromuscular junction blockade with rocuronium bromide. In 3 additional healthy volunteers we searched for F-waves to disclose whether percussion excites axons within the muscle.

RESULTS

Responses from 28 neurologically healthy patients (15 women) were analyzed after exclusion of 2 due to technical problems. Mean age (SD) was 28 (9) years. Maximal dorsiflexion of the ankle was not significantly modified by neuromuscular junction blockade (mean difference 0.01 mV [95%CI, -0.07 to 0.08], p=0.879). Muscle percussion evoked F-waves in the 3 healthy volunteers tested.

CONCLUSIONS

Maximal contraction response to muscle percussion has a muscular rather than a neural origin. However, percussion also excites axons within the muscle.

SIGNIFICANCE

These findings may provide clues to understand the changes observed in neuromuscular disorders.

How do authors of systematic reviews deal with research malpractice and misconduct in original studies? A cross-sectional analysis of systematic reviews and survey of their authors

OBJECTIVES

To study whether systematic reviewers apply procedures to counter-balance some common forms of research malpractice such as not publishing completed research, duplicate publications, or selective reporting of outcomes, and to see whether they identify and report misconduct.

DESIGN

Cross-sectional analysis of systematic reviews and survey of their authors.

PARTICIPANTS

118 systematic reviews published in four journals (Ann Int Med, BMJ, JAMA, Lancet), and the Cochrane Library, in 2013.

MAIN OUTCOMES AND MEASURES

Number (%) of reviews that applied procedures to reduce the impact of: (1) publication bias (through searching of unpublished trials), (2) selective outcome reporting (by contacting the authors of the original studies), (3) duplicate publications, (4) sponsors' and (5) authors' conflicts of interest, on the conclusions of the review, and (6) looked for ethical approval of the studies. Number (%) of reviewers who suspected misconduct are reported. The procedures applied were compared across journals.

RESULTS

80 (68%) reviewers confirmed their data. 59 (50%) reviews applied three or more procedures; 11 (9%) applied none. Unpublished trials were searched in 79 (66%) reviews. Authors of original studies were contacted in 73 (62%). Duplicate publications were searched in 81 (69%). 27 reviews (23%) reported sponsors of the included studies; 6 (5%) analysed their impact on the conclusions of the review. Five reviews (4%) looked at conflicts of interest of study authors; none of them analysed their impact. Three reviews (2.5%) looked at ethical approval of the studies. Seven reviews (6%) suspected misconduct; only 2 (2%) reported it explicitly. Procedures applied differed across the journals.

CONCLUSIONS

Only half of the systematic reviews applied three or more of the six procedures examined. Sponsors, conflicts of interest of authors and ethical approval remain overlooked. Research misconduct is sometimes identified, but rarely reported. Guidance on when, and how, to report suspected misconduct is needed.

Interventions for treating bisphosphonate-related osteonecrosis of the jaw (BRONJ)

BACKGROUND

Bisphosphonate drugs can be used to prevent and treat osteoporosis and to reduce symptoms and complications of metastatic bone disease; however, they are associated with a rare but serious adverse event: osteonecrosis of the maxillary and mandibular bones. This condition is called bisphosphonate-related osteonecrosis of the jaw or BRONJ. BRONJ is diagnosed when people who are taking, or have previously taken, bisphosphonates have exposed bone in the jaw area for more than eight weeks in the absence of radiation treatment. There is currently no "gold standard" of treatment for BRONJ. The three broad categories of intervention are conservative approaches (e.g. mouth rinse, antibiotics), surgical interventions and adjuvant non-surgical strategies (e.g. hyperbaric oxygen therapy, platelet-rich plasma), which can be used in combination.

OBJECTIVES

To determine the efficacy and safety of any intervention aimed at treating BRONJ.

SEARCH METHODS

We searched the following databases to 15 December 2015: the Cochrane Oral Health Group Trials Register, the Cochrane Breast Cancer Group Trials Register (20 September 2011), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via Ovid, EMBASE via Ovid, CancerLit via PubMed, CINAHL via EBSCO and AMED via Ovid. We scanned the references cited in retrieved articles and contacted experts in the field, the first authors of included papers, study sponsors, other bisphosphonates investigators and pharmaceutical companies. We searched for ongoing trials through contact with trialists and by searching the US National Institutes of Health Trials Register (clinicaltrials.gov) and the World Health Organization Clinical Trials Registry Platform. We also conducted a grey literature search to September 2015.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the effects of any treatment for BRONJ with another treatment or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, assessed the risk of bias in the included trials and extracted data. When in dispute, we consulted a third review author.

MAIN RESULTS

One small trial at high risk of bias met the inclusion criteria. The trial randomised 49 participants, most of whom had cancer. It compared standard care (defined as surgery, antibiotics and oral rinses at the discretion of the oral-maxillofacial surgeon) to standard care plus hyperbaric oxygen therapy (2 atmospheres twice a day for 40 treatments). The trial measured the percentage of participants who improved or healed at three, six, 12 and 18 months and last contact. It also measured mean weekly pain scores.At three months, the study found that the participants in intervention group were more likely to have an improvement in their osteonecrosis than the standard care group participants (risk ratio (RR) 1.94, 95% confidence interval (CI) 1.01 to 3.74). There was no clear difference between the groups for the outcome 'healed' at three months (RR 3.60, 95% CI 0.87 to 14.82). There was no clear difference between the groups for improvement or healing when they were evaluated at six, 12 and 18 months and last contact.The study did not give any information on adverse events.Although the findings suggest adjunctive hyperbaric oxygen improved BRONJ, the quality of the evidence is very low since the only study was underpowered and was at high risk of bias due to lack of blinding, cross-over of participants between groups and very high attrition (50% at 12 months and 80% at 18 months in this study, which was designed for an intended follow-up of 24 months).

AUTHORS' CONCLUSIONS

There is a lack of evidence from randomised controlled trials to guide treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ). One small trial at high risk of bias evaluated hyperbaric oxygen therapy (HBO) as an adjunct to "standard" care and could not confirm or refute the effectiveness of HBO. There are two ongoing trials of teriparatide treatment for BRONJ. We found no randomised controlled trials of any other BRONJ treatments. High quality randomised controlled trials are needed. We provide recommendations for their focus and design.

Erythromycin for Gastric Emptying in Patients Undergoing General Anesthesia for Emergency Surgery: A Randomized Clinical Trial

IMPORTANCE

Patients undergoing emergency procedures under general anesthesia have impaired gastric emptying and are at high risk for aspiration of gastric contents. Erythromycin has strong gastric prokinetic properties.

OBJECTIVE

To evaluate the efficacy of erythromycin lactobionate in gastric emptying in patients undergoing emergency surgery.

DESIGN, SETTING, AND PARTICIPANTS

The Erythro-Emerge trial was a single-center, randomized, double-blinded, placebo-controlled clinical trial in patients undergoing emergency surgery under general anesthesia at Geneva University Hospitals. We included 132 patients from March 25, 2009, through April 10, 2013, and all patients completed the study. Randomization was stratified for trauma and nontrauma procedures. The randomization code was opened on April 23, 2013, and analyses were performed through July 26, 2013. We performed an intention-to-treat analysis.

INTERVENTIONS

Patients were randomized to intravenous erythromycin lactobionate, 3 mg/kg, or placebo 15 minutes before tracheal intubation. Patients were followed up for 24 hours.

MAIN OUTCOMES AND MEASURES

The primary outcome was a clear stomach, defined as less than 40 mL of liquids and no solids and identified through endoscopy immediately after intubation. The secondary outcome was the pH level of residual gastric content.

RESULTS

A clear stomach was diagnosed in 42 of 66 patients (64%) receiving placebo compared with 53 of 66 patients (80%) receiving erythromycin (risk ratio, 1.26 [95% CI, 1.01-1.57]). In the population undergoing surgery for nontrauma, the association between receipt of erythromycin and having a clear stomach (adjusted odds ratio [95% CI]) was statistically significant (13.4 [1.49-120]; P = .02); in the population undergoing surgery for trauma, it was not (1.81 [0.64-5.16]; P = .26). Median (interquartile range) pH of the residual gastric liquid was 2 (1-4) in 36 patients receiving placebo and 6 (3-7) in 16 receiving erythromycin (P = .002). Patients receiving erythromycin had nausea (20 [30%] vs 4 [6%]) and stomach cramps (15 [23%] vs 2 [3%]) more often than those receiving placebo. One patient receiving erythromycin vomited before induction of anesthesia.

CONCLUSIONS AND RELEVANCE

In patients undergoing general anesthesia for emergency procedures, erythromycin administration increased the proportion with a clear stomach and decreased the acidity of residual gastric liquid. Erythromycin was particularly efficacious in the nontrauma population. Adverse effects were minor. Further large-scale studies are warranted to confirm the potential of erythromycin to reduce the incidence of bronchoaspiration in patients undergoing emergency surgery.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00827216.

Alternative intubation techniques vs Macintosh laryngoscopy in patients with cervical spine immobilization: systematic review and meta-analysis of randomized controlled trials

Background. Immobilization of the cervical spine worsens tracheal intubation conditions. Various intubation devices have been tested in this setting. Their relative usefulness remains unclear.

Methods. We searched MEDLINE, EMBASE, and the Cochrane Library for randomized controlled trials comparing any intubation device with the Macintosh laryngoscope in human subjects with cervical spine immobilization. The primary outcome was the risk of tracheal intubation failure at the first attempt. Secondary outcomes were quality of glottis visualization, time until successful intubation, and risk of oropharyngeal complications.

Results. Twenty-four trials (1866 patients) met inclusion criteria. With alternative intubation devices, the risk of intubation failure was lower compared with Macintosh laryngoscopy [risk ratio (RR) 0.53; 95% confidence interval (CI) 0.35–0.80]. Meta-analyses could be performed for five intubation devices (Airtraq, Airwayscope, C-Mac, Glidescope, and McGrath). The Airtraq was associated with a statistically significant reduction of the risk of intubation failure at the first attempt (RR 0.14; 95% CI 0.06–0.33), a higher rate of Cormack–Lehane grade 1 (RR 2.98; 95% CI 1.94–4.56), a reduction of time until successful intubation (weighted mean difference −10.1 s; 95% CI −3.2 to −17.0), and a reduction of oropharyngeal complications (RR 0.24; 95% CI 0.06–0.93). Other devices were associated with improved glottis visualization but no statistically significant differences in intubation failure or time to intubation compared with conventional laryngoscopy.

Conclusions. In situations where the spine is immobilized, the Airtraq device reduces the risk of intubation failure. There is a lack of evidence for the usefulness of other intubation devices.

Ability of a meta-analysis to prevent redundant research: systematic review of studies on pain from propofol injection

OBJECTIVE

To examine whether, according to the conclusions of a 2000 systematic review with meta-analysis on interventions to prevent pain from propofol injection that provided a research agenda to guide further research on the topic, subsequently published trials were more often optimally blinded, reported on children, and used the most efficacious intervention as comparator; and to check whether the number of new trials published each year had decreased and whether the designs of trials that cited the review differed from those that did not.

STUDY DESIGN

Systematic review comparing old trials (published before, and included in, the review) with new trials (published afterwards).

DATA SOURCES

Medline, Cochrane, Embase, and bibliographies to January 2013.

ELIGIBILITY CRITERIA FOR STUDY SELECTION

Randomised studies testing any intervention to prevent pain from propofol injection in humans.

RESULTS

136 new trials (19,778 patients) were retrieved. Compared with the 56 old trials (6264 patients), the proportion of optimally blinded trials had increased from 10.7% to 38.2% (difference 27.5%, 95% confidence interval 16.0% to 39.0%, P<0.001), and the proportion of trials that used the most efficacious intervention as comparator had increased from 12.5% to 27.9% (difference 15.4%, 4.0% to 26.9%, P=0.022). The proportion of paediatric trials had increased from 5.4% to 12.5%, although this was not significant (difference 7.1%, -1.0% to 15.2%, P=0.141). The number of new trials published each year was significantly higher (median number/year 12 (range 7-20) v 2.5 (0-9), P<0.001) with no obvious decreasing trend. 72.8% (n=99) of the new trials cited the review, with their designs similar to trials not citing the review. Only 36.0% (n=49) of the new trials were considered clinically relevant since they used the most efficacious intervention as comparator or included a paediatric population.

CONCLUSIONS

The impact of the systematic review on the design of subsequent research was low. There was an improvement in the reporting of optimal blinding procedures and a tendency towards an increase in the proportion of paediatric trials. The most efficacious intervention was more often chosen as comparator but remained marginally used, and the number of trials published per year had not decreased. The use of systematic reviews should be encouraged to inform rational, and thus ethical, trial design and improve the relevance of new research.

Fate of articles that warranted retraction due to ethical concerns: a descriptive cross-sectional study

Objective

To study journals' responses to a request from the State Medical Association of Rheinland-Pfalz, Germany, to retract 88 articles due to ethical concerns, and to check whether the resulting retractions followed published guidelines.

Design

Descriptive cross-sectional study.

Population

88 articles (18 journals) by the anaesthesiologist Dr. Boldt, that warranted retraction.

Method

According to the recommendations of the Committee on Publication Ethics, we regarded a retraction as adequate when a retraction notice was published, linked to the retracted article, identified the title and authors of the retracted article in its heading, explained the reason and who took responsibility for the retraction, and when the retracted article was freely accessible and marked using a transparent watermark that preserved original content. Two authors extracted data independently (January 2013) and contacted editors-in-chief and publishers for clarification in cases of inadequate retraction.

Results

Five articles (6%) fulfilled all criteria for adequate retraction. Nine (10%) were not retracted (no retraction notice published, full text article not marked). 79 (90%) retraction notices were published, 76 (86%) were freely accessible, but only 15 (17%) were complete. 73 (83%) full text articles were marked as retracted, of which 14 (16%) had an opaque watermark hiding parts of the original content, and 11 (13%) had all original content deleted. 59 (67%) retracted articles were freely accessible. One editor-in-chief stated personal problems as a reason for incomplete retractions, eight blamed their publishers. Two publishers cited legal threats from Dr. Boldt's co-authors which prevented them from retracting articles.

Conclusion

Guidelines for retracting articles are incompletely followed. The role of publishers in the retraction process needs to be clarified and standards are needed on marking retracted articles. It remains unclear who should check that retractions are done properly. Legal safeguards are required to allow retraction of articles against the wishes of authors.

Ventilation strategies in obese patients undergoing surgery: a quantitative systematic review and meta-analysis

BACKGROUND

Pathophysiological changes due to obesity may complicate mechanical ventilation during general anaesthesia. The ideal ventilation strategy is expected to optimize gas exchange and pulmonary mechanics and to reduce the risk of respiratory complications.

METHODS

Systematic search (databases, bibliographies, to March 2012, all languages) was performed for randomized trials testing intraoperative ventilation strategies in obese patients (BMI ≥ 30 kg m(-2)), and reporting on gas exchange, pulmonary mechanics, or pulmonary complications. Meta-analyses were performed when data from at least three studies or 100 patients could be combined.

RESULTS

Thirteen studies (505 obese surgical patients) reported on a variety of ventilation strategies: pressure- or volume-controlled ventilation (PCV, VCV), various tidal volumes, and different PEEP or recruitment manoeuvres (RM), and combinations thereof. Definitions and reporting of endpoints were inconsistent. In five trials (182 patients), RM added to PEEP compared with PEEP alone improved intraoperative PaO2/FIO2 ratio [weighted mean difference (WMD), 16.2 kPa; 95% confidence interval (CI), 8.0-24.4] and increased respiratory system compliance (WMD, 14 ml cm H(2)O(-1); 95% CI, 8-20). Arterial pressure remained unchanged. In four trials (100 patients) comparing PCV with VCV, there was no difference in PaO2/FIO2 ratio, tidal volume, or arterial pressure. Comparison of further ventilation strategies or combination of other outcomes was not feasible. Data on postoperative complications were seldom reported.

CONCLUSIONS

The ideal intraoperative ventilation strategy in obese patients remains obscure. There is some evidence that RM added to PEEP compared with PEEP alone improves intraoperative oxygenation and compliance without adverse effects. There is no evidence of any difference between PCV and VCV.

Controversies in altitude medicine

Two areas of controversy in altitude medicine are briefly reviewed. The first area concerns the prevention of acute mountain sickness (AMS) with acetazolamide. It is argued that for full prevention of AMS symptoms 500-750mg a day is necessary, but that symptom attenuation may be possible with lower doses. The second concerns the study of the relationship between cerebral blood flow and acute mountain sickness. Multiple methodological problems can be identified; some are related to the experimental settings and some to limitations of the technical tools that are used to estimate cerebral blood flow. For the moment it remains unknown whether or not a change in cerebral blood flow is an etiological factor for the development of acute mountain sickness.

Intravenous buspirone for the prevention of postoperative nausea and vomiting

RATIONALE

Buspirone, a partial 5HT(1A) agonist and D₂ and D₃ antagonist, has shown promising antiemetic efficacy when given parenterally in animal models, but its efficacy for the prevention of postoperative nausea and vomiting (PONV) is unknown.

OBJECTIVE

To study the efficacy and dose-responsiveness of intravenous buspirone for the prevention of PONV.

METHODS

A randomised, double-blind, placebo-controlled study was performed in adults at moderate to high PONV risk undergoing surgery with a general anaesthetic. Patients were randomised to receive an intravenous dose of buspirone (0.3, 1.0, 2.0, 3.0 mg) or placebo at the end of surgery. The primary endpoint was the cumulative 24-h PONV incidence (i.e. any nausea and/or vomiting). Vomiting included retching. Nausea was defined as a score of ≥ 4 on an 11-point verbal rating scale running from zero (no nausea) to ten (the worst nausea imaginable).

RESULTS

A total of 257 patients received the study drug and fulfilled the criteria for inclusion in the primary efficacy and safety analyses. With placebo, the mean 24-h PONV incidence was 49.0 % (90 % confidence interval [CI] 37.5-60.5 %). With buspirone, that incidence ranged from a mean of 40.8 % (29.3-52.4 %) in the 1 mg arm to 58.0 % (46.5-69.5 %) in the 0.3 mg arm (P > 0.05 for all comparisons). There was no difference between placebo and buspirone at any dose for any other efficacy endpoint, nor in the number or severity of adverse events or any other safety measures.

CONCLUSION

We were unable to show that intravenous single-dose buspirone, at the tested dose-range, was effective at preventing PONV in surgical adult patients. The present study emphasises the difficulty in extrapolating from animal models of emesis to clinical efficacy in PONV.

Transcutaneous nicotine does not prevent postoperative nausea and vomiting: a randomized controlled trial

AIMS

There is empirical evidence that smokers are less likely to suffer from postoperative nausea and vomiting (PONV). We sought to investigate whether transcutaneus nicotine prevents PONV.

METHODS

Non-smokers receiving general anaesthesia for surgery were randomly allocated to Nicotinell Patch 10cm(2) (TTS 10), containing 17.5mg of nicotine (average delivery rate, 7mg 24h(-1) ) or matching placebo patch. Patches were applied 1h before surgery and were left in situ until 24h after surgery (or until the first PONV symptoms occurred).

RESULTS

We randomized 90 patients (45 nicotine, 45 placebo). In the post-anaesthetic care unit, the incidence of nausea was 22.2% with nicotine and 24.4% with placebo (P= 0.80), and the incidence of vomiting was 20.0% with nicotine and 17.8% with placebo (P= 0.78). Cumulative 24h incidence of nausea was 42.2% with nicotine and 40.0% with placebo (P= 0.83), and of vomiting was 31.1% with nicotine and 28.9% with placebo (P= 0.81). PONV episodes tended to occur earlier in the nicotine group. Postoperative headache occurred in 17.8% of patients treated with nicotine and in 15.6% with placebo (P= 0.49). More patients receiving nicotine reported a low quality of sleep during the first postoperative night (26.7% vs. 6.8% with placebo; P= 0.01).

CONCLUSIONS

Non-smokers receiving a prophylactic nicotine patch had a similar incidence of PONV during the first 24h and tended to develop PONV symptoms earlier compared with controls. They had a significantly increased risk of insomnia during the first postoperative night.

Time course of rocuronium-induced neuromuscular block after pre-treatment with magnesium sulphate: a randomised study

BACKGROUND

A previously published study suggested that pre-treatment with magnesium sulphate (MgSO(4)) had no impact on the speed of onset of rocuronium-induced neuromuscular block. We set out to verify this assumption.

METHODS

Eighty patients (18-60 years) were randomly allocated to MgSO(4) 60 mg/kg or placebo (saline). Study drugs were given intravenously for 15 min before induction of anaesthesia with propofol, sufentanil and rocuronium 0.6 mg/kg. Anaesthesia was maintained with a target-controlled propofol infusion. Neuromuscular transmission was measured using train-of-four (TOF)-Watch SX acceleromyography.

RESULTS

Onset was analysed in 37 MgSO(4) and 38 saline patients, and recovery in 35 MgSO(4) and 37 saline patients. Onset time (to 95% depression of T1) was on average 77 [SD=18] s with MgSO(4) and 120 [48] s with saline (P<0.001). The total recovery time (DurTOF0.9) was on average 73.2 [22] min with MgSO(4) and 57.8 [14.2] min with saline (P<0.003). The clinical duration (Dur25%) was on average 44.7 [14] min with MgSO(4) and 33.2 [8.1] min with saline (P<0.0002). The recovery index (Dur25-75%) was on average 14.0 [6] min with MgSO(4) and 11.2 [5.2] min with saline (P<0.02). The recovery time (Dur25%TOF0.9) was on average 28.5 [11.7] min with MgSO(4) and 24.7 [8.4] min with saline (P=0.28).

CONCLUSION

Magnesium sulphate given 15 min before propofol anaesthesia reduces the onset time of rocuronium by about 35% and prolongs the total recovery time by about 25%.

Benefit and risk of intrathecal morphine without local anaesthetic in patients undergoing major surgery: meta-analysis of randomized trials

Intrathecal morphine without local anaesthetic is often added to a general anaesthetic to prevent pain after major surgery. Quantification of benefit and harm and assessment of dose-response are needed. We performed a meta-analysis of randomized trials testing intrathecal morphine alone (without local anaesthetic) in adults undergoing major surgery under general anaesthesia. Twenty-seven studies (15 cardiac-thoracic, nine abdominal, and three spine surgery) were included; 645 patients received intrathecal morphine (dose-range, 100-4000 microg). Pain intensity at rest was decreased by 2 cm on the 10 cm visual analogue scale up to 4 h after operation and by about 1 cm at 12 and 24 h. Pain intensity on movement was decreased by 2 cm at 12 and 24 h. Opioid requirement was decreased intraoperatively, and up to 48 h after operation. Morphine-sparing at 24 h was significantly greater after abdominal surgery {weighted mean difference, -24.2 mg [95% confidence interval (CI) -29.5 to -19.0]}, compared with cardiac-thoracic surgery [-9.7 mg (95% CI -17.6 to -1.80)]. The incidence of respiratory depression was increased with intrathecal morphine [odds ratio (OR) 7.86 (95% CI 1.54-40.3)], as was the incidence of pruritus [OR 3.85 (95% CI 2.40-6.15)]. There was no evidence of linear dose-responsiveness for any of the beneficial or harmful outcomes. In conclusion, intrathecal morphine decreases pain intensity at rest and on movement up to 24 h after major surgery. Morphine-sparing is more pronounced after abdominal than after cardiac-thoracic surgery. Respiratory depression remains a major safety concern.

Dexamethasone and risk of nausea and vomiting and postoperative bleeding after tonsillectomy in children: a randomized trial

CONTEXT

Dexamethasone is widely used to prevent postoperative nausea and vomiting (PONV) in pediatric tonsillectomy.

OBJECTIVE

To assess whether dexamethasone dose-dependently reduces the risk of PONV at 24 hours after tonsillectomy.

DESIGN, SETTING, AND PATIENTS

Randomized placebo-controlled trial conducted among 215 children undergoing elective tonsillectomy at a major public teaching hospital in Switzerland from February 2005 to December 2007.

INTERVENTIONS

Children were randomly assigned to receive dexamethasone (0.05, 0.15, or 0.5 mg/kg) or placebo intravenously after induction of anesthesia. Acetaminophen-codeine and ibuprofen were given as postoperative analgesia. Follow-up continued until the 10th postoperative day.

MAIN OUTCOME MEASURES

The primary end point was prevention of PONV at 24 hours; secondary end points were decrease in the need for ibuprofen at 24 hours and evaluation of adverse effects.

RESULTS

At 24 hours, 24 of 54 participants who received placebo (44%; 95% confidence interval [CI], 31%-59%) had experienced PONV compared with 20 of 53 (38%; 95% CI, 25%-52%), 13 of 54 (24%; 95% CI, 13%-38%), and 6 of 52 (12%; 95% CI, 4%-23%) who received dexamethasone at 0.05, 0.15, and 0.5 mg/kg, respectively (P<.001 for linear trend). Children who received dexamethasone received significantly less ibuprofen. There were 26 postoperative bleeding episodes in 22 children. Two of 53 (4%; 95% CI, 0.5%-13%) children who received placebo had bleeding compared with 6 of 53 (11%; 95% CI, 4%-23%), 2 of 51 (4%; 95% CI, 0.5%-13%), and 12 of 50 (24%; 95% CI, 13%-38%) who received dexamethasone at 0.05, 0.15, and 0.5 mg/kg, respectively (P = .003). Dexamethasone, 0.5 mg/kg, was associated with the highest bleeding risk (adjusted relative risk, 6.80; 95% CI, 1.77-16.5). Eight children had to undergo emergency reoperation because of bleeding, all of whom had received dexamethasone. The trial was stopped early for safety reasons.

CONCLUSION

In this study of children undergoing tonsillectomy, dexamethasone decreased the risk of PONV dose dependently but was associated with an increased risk of postoperative bleeding.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00403806.

Protective effects of epidural analgesia on pulmonary complications after abdominal and thoracic surgery: a meta-analysis

OBJECTIVE

To review the impact of epidural vs systemic analgesia on postoperative pulmonary complications.

DATA SOURCES

Search of databases (1966 to March 2006) and bibliographies.

STUDY SELECTION

Inclusion criteria were randomized comparison of epidural vs systemic analgesia lasting 24 hours or longer postoperatively and reporting of pulmonary complications, lung function, or gas exchange. Fifty-eight trials (5904 patients) were included.

DATA EXTRACTION

Articles were reviewed and data extracted. Data were combined using fixed-effect and random-effects models.

DATA SYNTHESIS

The odds of pneumonia were decreased with epidural analgesia (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.43-0.68), independent of site of surgery or catheter insertion, duration of analgesia, or regimen. The effect was weaker in trials that used patient-controlled analgesia in controls (OR, 0.64; 95% CI, 0.49-0.83) compared with trials that did not (OR, 0.30; 95% CI, 0.18-0.49) and in larger studies (OR, 0.62; 95% CI, 0.47-0.81) compared with smaller studies (OR, 0.37; 95% CI, 0.23-0.58). From 1971-2006, the incidence of pneumonia with epidural analgesia remained about 8% but decreased from 34% to 12% with systemic analgesia (P < .001); consequently, the relative benefit of epidural analgesia decreased also. Epidural analgesia reduced the need for prolonged ventilation or reintubation, improved lung function and blood oxygenation, and increased the risk of hypotension, urinary retention, and pruritus. Technical failures occurred in 7%.

CONCLUSION

Epidural analgesia protects against pneumonia following abdominal or thoracic surgery, although this beneficial effect has lessened over the last 35 years because of a decrease in the baseline risk.

Clonidine as an adjuvant to intrathecal local anesthetics for surgery: systematic review of randomized trials

BACKGROUND AND OBJECTIVES

Clonidine is added to intrathecal local anesthetics to improve intraoperative analgesia and to increase the duration of sensory and motor block. The aim of this systematic review is to quantify beneficial and harmful effects of clonidine when used as an adjuvant to intrathecal local anesthetics for surgery.

METHODS

We included data from 22 randomized trials (1,445 patients) testing a large variety of doses of clonidine, added to intrathecal bupivacaine, mepivacaine, prilocaine, or tetracaine.

RESULTS

Clonidine 15 to 150 microg prolonged in a linear, dose-dependent manner, the time to 2 segment regression (range of means, 14 to 75 minutes) and the time to regression to L2 (range of means, 11 to 128 minutes). The time to first analgesic request (median 101 minutes, range 35 to 310) and of motor block (median 47 minutes, range 6 to 131) was prolonged without evidence of dose-responsiveness. Time to achieve complete sensory or motor block, and extent of cephalic spread remained unchanged. There were fewer episodes of intraoperative pain with clonidine (relative risk, 0.24; 95% confidence interval [CI], 0.09-0.64; number needed to treat, 13) but more episodes of arterial hypotension (relative risk, 1.81; 95% CI 1.44-2.28; number needed to harm, 8) without evidence of dose-responsiveness. The risk of bradycardia was unchanged.

CONCLUSIONS

This study may serve as a rational basis to help clinicians decide whether or not to combine clonidine with an intrathecal local anesthetic for surgery. The optimal dose of clonidine, however, remains unknown.

Impact of the intubation model on the efficacy of rocuronium during rapid sequence intubation: systematic review of randomized trials

BACKGROUND

Propofol-rocuronium is thought to be superior to thiopental-rocuronium for rapid sequence intubation (RSI). The role of the intubation model per se has never been investigated.

METHODS

Randomized comparisons of rocuronium with succinylcholine for true RSI (administration of muscle relaxant immediately after the hypnotic, intubation within 60 s) or modified RSI (delay between administration of the hypnotic and the muscle relaxant, intubation within 60 s) were sought. Good or excellent intubation conditions were expressed as relative risks (RR) with 95% confidence intervals (CI).

RESULTS

Twelve trials (1,471 patients) used a true RSI. With propofol for induction, RR for good or excellent intubation conditions with conventional rocuronium doses (0.6-0.7 mg/kg) was 0.95 (95%CI, 0.90-1.00), with high doses (0.9-1.2 mg/kg) was 0.96 (0.92-1.01) compared with succinylcholine. With thiopental for induction, RR with conventional rocuronium doses was 0.69 (0.61-0.78) and with high doses was 0.99 (0.95-1.03). Nine trials (340 patients) used a modified RSI. With propofol for induction, RR with conventional rocuronium doses was 0.98 (0.91-1.06); data on high rocuronium doses were lacking. With thiopental for induction, RR with conventional rocuronium doses was 0.97 (0.92-1.02) and with high doses was 1.0. There was no evidence that concomitantly used opioids or the dose of the induction agent had an impact on intubation conditions, independent of the intubation model.

CONCLUSION

The efficacy of rocuronium for RSI is influenced by both, the induction agent and the intubation model. To test the clinical usefulness of alternatives to succinylcholine for RSI, a true RSI model should be used.

Klinische Pharmakologie

The rule of three describes three steps which are needed for an optimal control of postoperative nausea and vomiting (PONV). Firstly, patients at high risk of PONV need to be identified. Knowledge about predictive factors may help to identify patients who may best profit from prophylaxis and those where prophylaxis is not worthwhile since the baseline risk is too low. Secondly, for high-risk patients a low emetogenic anaesthesia technique should be chosen, and thirdly, these patients should additionally receive a prophylactic antiemetic cocktail. At present, butyrophenones (e.g. droperidol), 5-HT(3) receptor antagonists ("setrons") and steroids (e.g. dexamethasone) are the most rational choices for the antiemetic cocktail. Although there is strong evidence that there is an additive effect when these antiemetics are combined, economic constraints may influence the number of antiemetics that are eventually chosen. Identification of high-risk patients remains the most difficult part of the rule of three. Risk scores have been proposed and have been widely implemented in clinical practice. The sensitivity and specificity of such scores, however, remain particularly unsatisfactory. Unless more reliable risk scores are developed, aggressive treatment of established PONV symptoms may be more useful and more cost-effective than prophylaxis for many patients.

Algorithms for the prevention of postoperative nausea and vomiting: an efficacy and efficiency simulation

BACKGROUND AND OBJECTIVE

A number of algorithms for the prevention of postoperative nausea and vomiting have been proposed. Their efficacy and efficiency remains unclear.

METHODS

We assumed that four antiemetic interventions were similarly effective and achieved additive effects when combined. We applied published and hypothetical algorithms for the prevention of postoperative nausea and vomiting to patient populations with different baseline risks. As indicators of efficacy and efficiency we computed for each baseline risk and each algorithm the total number of patients receiving prophylaxis, the total number of administered interventions, the cumulative 24 h incidence of postoperative nausea and vomiting, and an Efficiency Index (i.e. the number of administered interventions divided by the achieved absolute risk reduction). This was done for cohorts of 100 patients.

RESULTS

Ten algorithms were tested in seven populations with different baseline risks. Algorithms were fixed (> or = 1 intervention given to all patients, independent of baseline risk) or risk-adapted (> or = 1 intervention administered depending on the presumed baseline risk). Risk-adapted algorithms were escalating (the greater the baseline risk, the more interventions are given) or dichotomous (a fixed number of interventions is given to high-risk patients only). With some algorithms, when applied to selected patient populations, the average postoperative nausea and vomiting incidence could be decreased below 15%; however, none produced consistent postoperative nausea and vomiting incidences below 20% across all populations. With all, the number of administered antiemetic interventions was the major factor for improved efficacy. Depending on the baseline risk, some algorithms offered potential towards improved efficiency.

CONCLUSIONS

Despite improved knowledge on risk factors and antiemetic strategies, none of the tested algorithms completely prevents postoperative nausea and vomiting and none is universally applicable. Anesthesiologists should try to identify the most useful antiemetic strategy for a specific setting. That strategy may be prophylactic or therapeutic or a combination of both, and it should consider institutional policies and individual baseline risks.

An evaluation of a single dose of magnesium to supplement analgesia after ambulatory surgery: randomized controlled trial

BACKGROUND

Previous studies have suggested that magnesium may be a useful adjuvant to postoperative analgesia.

METHODS

We randomized adults undergoing ambulatory ilioinguinal hernia repair or varicose vein operation under general anesthesia (propofol, fentanyl, isoflurane-N2O) to receive magnesium sulfate 4 g IV or physiological saline after induction. All patients preoperatively received diclofenac 100 mg rectally and those undergoing hernia repair had a postoperative ilioinguinal-iliohypogastric nerve block done. Pain, analgesic consumption, and adverse effects were recorded in the recovery room and, using a questionnaire, up to 3 days postoperatively.

RESULTS

We randomized 200 patients (101 magnesium, 99 placebo). There were no differences in hemodynamic variables before and immediately after study drug injection. Pain intensity at rest and on movement after 1, 2, and 4 h, time to first rescue analgesic, and cumulative numbers of non-opioid and opioid analgesics were similar among groups. There was no difference in the incidence of postoperative nausea and vomiting, dizziness, headache, or fainting. The incidence of postoperative shivering was significantly lower in the magnesium group (4% vs 13.1%, P = 0.0232). Adequately completed questionnaires were returned by 84 placebo and 82 magnesium patients. There was no difference between groups for any of the analyzed outcomes during the first three postoperative days, neither for patients undergoing inguinal hernia repair nor for those undergoing varicose vein stripping.

CONCLUSIONS

In patients undergoing ambulatory ilioinguinal hernia repair or varicose vein operations under general anesthesia supplemented with other analgesic adjuvants, pretreatment with IV magnesium sulfate 4 g has no impact on postoperative pain and analgesic consumption.

Magnesium as an adjuvant to postoperative analgesia: a systematic review of randomized trials

BACKGROUND

Randomized trials have reached different conclusions as to whether magnesium is a useful adjuvant to postoperative analgesia.

METHODS

We performed a comprehensive search (electronic databases, bibliographies, all languages, to 4.2006) for randomized comparisons of magnesium and placebo in the surgical setting. Information on postoperative pain intensity and analgesic requirements was extracted from the trials and compared qualitatively. Dichotomous data on adverse effects were combined using classic methods of meta-analysis.

RESULTS

Fourteen randomized trials (778 patients, 404 received magnesium) tested magnesium laevulinate, gluconate or sulfate. With magnesium, postoperative pain intensity was significantly decreased in four (29%) trials, was no different from placebo in seven (50%), and was increased in one (7%); two trials (14%) did not report on pain intensity. With magnesium, postoperative analgesic requirements were significantly reduced in eight (57%) trials, were no different from placebo in five (36%), and were increased in one (7%). Magnesium-treated patients had less postoperative shivering (relative risk 0.38, 95% confidence interval 0.17-0.88, number-needed-to-treat 14). Seven trials reported on magnesium serum levels. In all, serum levels were increased in patients who received magnesium; in six, serum levels were decreased in those who received placebo.

CONCLUSIONS

These trials do not provide convincing evidence that perioperative magnesium may have favorable effects on postoperative pain intensity and analgesic requirements. Perioperative magnesium supplementation prevents postoperative hypomagnesemia and decreases the incidence of postoperative shivering. It may be worthwhile to further study the role of magnesium as a supplement to postoperative analgesia, since this relatively harmless molecule is inexpensive, and the biological basis for its potential antinociceptive effect is promising.

Do we need preemptive analgesia for the treatment of postoperative pain?

Preemptive analgesia means that an analgesic intervention is started before the noxious stimulus arises in order to block peripheral and central nociception. This afferent blockade of nociceptive impulses is maintained throughout the intra-operative and post-operative period. The goals of preemptive analgesia are, first, to decrease acute pain after tissue injury, second, to prevent pain-related pathologic modulation of the central nervous system, and third, to inhibit the persistence of postoperative pain and the development of chronic pain. So far, the promising results from animal models have not been translated into clinical practice. Therefore, clinicians should rely on conventional anaesthetic and analgesic methods with proven efficacy, i.e. a multimodal approach including the combination of strong opioids, non-opioid analgesics, and peripheral or neuraxial local anaesthetics that act at different sites of the pain pathways.

Are self-collected samples comparable to physician-collected cervical specimens for human papillomavirus DNA testing? A systematic review and meta-analysis

OBJECTIVE

To compare the detection rate of genital human papillomavirus (HPV) infection in self- and physician-obtained samples.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Studies published between 1966 and November 2005 identified through Medline and Embase that compared both sampling methods.

MAIN OUTCOME MEASURES

We calculated the concordance and kappa statistic between physician- and self-sampling and the difference between proportions of HPV positive samples. Weighted averages were reported with 95% confidence intervals (CI) using a random-effects model.

RESULTS

Eighteen studies (5441 participants) were included that evaluated broad HPV type categories, 10 (3688 patients) that of high-risk (HR) HPV and three (530) that of low-risk (LR) HPV. A high level of concordance of 0.87 (95%CI, 0.82 to 0.91) between self- and physician-sampling was obtained for detection of HPV DNA (kappa 0.66, 95%CI, 0.56 to 0.76). The prevalence difference of HPV DNA between sampling methods was -0.5 (95%CI, -2.8 to 1.8). Results were similar when restricting the analysis to HR-HPV but the prevalence of LR-HPV types was higher in self-collected samples.

CONCLUSION

Self-sampling was as sensitive as physician-obtained sampling to detect HR-HPV or HPV DNA. Self-sampling may be a suitable alternative method for studies on HPV transmission and vaccine trials.

Respiratory physiotherapy to prevent pulmonary complications after abdominal surgery: a systematic review

OBJECTIVES

To examine the efficacy of respiratory physiotherapy for prevention of pulmonary complications after abdominal surgery.

METHODS

We searched in databases and bibliographies for articles in all languages through November 2005. Randomized trials were included if they investigated prophylactic respiratory physiotherapy and pulmonary outcomes, and if the follow-up was at least 2 days. Efficacy data were expressed as risk differences (RDs) and number needed to treat (NNT), with 95% confidence intervals (CIs).

RESULTS

Thirty-five trials tested respiratory physiotherapy treatments. Of 13 trials with a "no intervention" control group, 9 studies (n = 883) did not report on significant differences, and 4 studies (n = 528) did: in 1 study, the incidence of pneumonia was decreased from 37.3 to 13.7% with deep breathing, directed cough, and postural drainage (RD, 23.6%; 95% CI, 7 to 40%; NNT, 4.3; 95% CI, 2.5 to 14); in 1 study, the incidence of atelectasis was decreased from 39 to 15% with deep breathing and directed cough (RD, 24%; 95% CI, 5 to 43%; NNT, 4.2; 95% CI, 2.4 to 18); in 1 study, the incidence of atelectasis was decreased from 77 to 59% with deep breathing, directed cough, and postural drainage (RD, 18%; 95% CI, 5 to 31%; NNT, 5.6; 95% CI, 3.3 to 19); in 1 study, the incidence of unspecified pulmonary complications was decreased from 47.7% to 21.4 to 22.2% with intermittent positive pressure breathing, or incentive spirometry, or deep breathing with directed cough (RD, 25.5 to 26.3%; NNT, 3.8 to 3.9). Twenty-two trials (n = 2,734) compared physiotherapy treatments without no intervention control subjects; no conclusions could be drawn.

CONCLUSIONS

There are only a few trials that support the usefulness of prophylactic respiratory physiotherapy. The routine use of respiratory physiotherapy after abdominal surgery does not seem to be justified.

Pharmacological prevention of serious anaphylactic reactions due to iodinated contrast media: systematic review

OBJECTIVE

To review the efficacy of pharmacological prevention of serious reactions to iodinated contrast media.

DESIGN

Systematic review.

DATA SOURCES

Systematic search (multiple databases, bibliographies, all languages, to October 2005) for randomised comparisons of pretreatment with placebo or no treatment (control) in patients receiving iodinated contrast media. Review methods Trial quality was assessed by all investigators. Information on trial design, population, interventions, and outcomes was abstracted by one investigator and cross checked by the others. Data were combined by using Peto odds ratios with 95% confidence intervals.

RESULTS

Nine trials (1975-96, 10 011 adults) tested H1 antihistamines, corticosteroids, and an H1-H2 combination. No trial included exclusively patients with a history of allergic reactions. Many outcomes were not allergy related, and only a few were potentially life threatening. No reports on death, cardiopulmonary resuscitation, irreversible neurological deficit, or prolonged hospital stays were found. In two trials, 3/778 (0.4%) patients who received oral methylprednisolone 2x32 mg or intravenous prednisolone 250 mg had laryngeal oedema compared with 11/769 (1.4%) controls (odds ratio 0.31, 95% confidence interval 0.11 to 0.88). In two trials, 7/3093 (0.2%) patients who received oral methylprednisolone 2x32 mg had a composite outcome (including shock, bronchospasm, and laryngospasm) compared with 20/2178 (0.9%) controls (odds ratio 0.28, 0.13 to 0.60). In one trial, 1/196 (0.5%) patients who received intravenous clemastine 0.03 mg/kg and cimetidine 2-5 mg/kg had angio-oedema compared with 8/194 (4.1%) controls (odds ratio 0.20, 0.05 to 0.76).

CONCLUSIONS

Life threatening anaphylactic reactions due to iodinated contrast media are rare. In unselected patients, the usefulness of premedication is doubtful, as a large number of patients need to receive premedication to prevent one potentially serious reaction. Data supporting the use of premedication in patients with a history of allergic reactions are lacking. Physicians who are dealing with these patients should not rely on the efficacy of premedication.