Pre-apneic capnography waveform abnormalities during procedural sedation and analgesia.

Capnography monitoring is recommended for use during procedural sedation. This study examined associations between capnography waveform abnormalities and the onset of apnea. Capnography waveforms from a sample of 102 participants undergoing moderate procedural sedation with bolus doses of midazolam and fentanyl were analyzed using a mixed effects Cox model. Patients were at increased risk of apnea (classified as end-tidal carbon dioxide concentration of zero) while demonstrating a capnography waveform abnormality classified as hypopnea (more than 10% increase or decrease from baseline end-tidal carbon dioxide concentration) (Hazard Ratio 2.14; 95% CI 1.75 to 2.62). Risk of apnea was not increased during capnography waveform abnormalities classified as bradypnea (capnography-derived respiratory rate less than 8 breaths/min) (Hazard Ratio 0.64; 95% CI 0.33 to 1.25). These estimates were similar when apneic episodes were defined as only those that lasted more than 20 s duration. Deciphering which capnography waveform abnormalities should promote intervention (and therefore alarms to signal the event to clinicians) from those that do not is an essential step towards successful implementation of this technology into practice. Our results indicate that using information about the history of previous capnography waveform abnormalities may be a promising solution to assist prediction of apneic episodes.

Accuracy and precision of transcutaneous carbon dioxide monitoring: a systematic review and meta-analysis.

BACKGROUND: Transcutaneous carbon dioxide (TcCO2) monitoring is a non-invasive alternative to arterial blood sampling. The aim of this review was to determine the accuracy and precision of TcCO2 measurements. METHODS: Medline and EMBASE (2000-2016) were searched for studies that reported on a measurement of PaCO2 that coincided with a measurement of TcCO2. Study selection and quality assessment (using the revised Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2)) were performed independently. The Grading Quality of Evidence and Strength of Recommendation approach was used to summarise the strength of the body of evidence. Pooled estimates of the mean bias between TcCO2 and PaCO2 and limits of agreement with outer 95% CIs (termed population limits of agreement) were calculated. RESULTS: The mean bias was -0.1 mm Hg and the population limits of agreement were -15 to 15 mm Hg for 7021 paired measurements taken from 2817 participants in 73 studies, which was outside of the clinically acceptable range (7.5 mm Hg). The lowest PaCO2 reported in the studies was 18 mm Hg and the highest was 103 mm Hg. The major sources of inconsistency were sensor location and temperature. The population limits of agreement were within the clinically acceptable range across 3974 paired measurements from 1786 participants in 44 studies that applied the sensor to the earlobe using the TOSCA and Sentec devices (-6 to 6 mm Hg). CONCLUSION: There are substantial differences between TcCO2 and PaCO2 depending on the context in which this technology is used. TcCO2 sensors should preferentially be applied to the earlobe and users should consider setting the temperature of the sensor higher than 42°C when monitoring at other sites. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO; CRD42017057450.

Cost-effectiveness of forced air warming during sedation in the cardiac catheterisation laboratory.

AIM: The aim of this study was to determine the cost-effectiveness of forced air warming (FAW) during sedation in a cardiac catheterisation laboratory. BACKGROUND: Forced air warming improves thermal comfort in comparison with standard care. It is not known whether the extra costs required for FAW are good value. DESIGN: Cost-effectiveness analysis alongside a randomized controlled trial conducted in 2016-2017. METHODS: A cost-effectiveness analysis was undertaken using Monte Carlo simulations from input distributions to estimate costs and effects associated with using FAW to reduce risk of thermal discomfort for patients receiving sedation in a cardiac catheterisation laboratory. A range of willingness to pay threshold values were tested with results plotted on a cost-effectiveness acceptability curve. Costs were calculated in Australian currency ($AUD). RESULTS: Estimated total costs were $5.21 (SD 3.26) higher per patient for FAW in comparison to standard care. Estimated probability of success (rating of thermal comfort) was 0.16 (0.06) higher for FAW. Forced air warming becomes more likely to result in a net benefit than standard care at a willingness to pay threshold of $34. CONCLUSION: Forced air warming could be considered cost-effective for procedures performed with sedation in a cardiac catheterisation laboratory if the extra cost of an incremental gain in thermal comfort is less than the decision maker's willingness to pay for it. Therefore, those responsible for decision-making regarding use of FAW in the cardiac catheterisation laboratory can use results of our model to decide if it represents good value for their organisation.

High quality of evidence is uncommon in Cochrane systematic reviews in Anaesthesia, Critical Care and Emergency Medicine.

BACKGROUND: The association between the quality of evidence in systematic reviews and authors' conclusions regarding the effectiveness of interventions relevant to anaesthesia has not been examined. OBJECTIVE: The objectives of this study were: to determine the proportion of systematic reviews in which the authors made a conclusive statement about the effect of an intervention; to describe the quality of evidence derived from outcomes in reviews that used the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) working group system for grading the quality of evidence; and to identify review characteristics associated with conclusiveness. DESIGN: Cross-sectional analysis of Cochrane systematic reviews from the Anaesthesia, Critical Care and Emergency Review Group was undertaken. DATA SOURCES: The Cochrane webpage was used to identify reviews for inclusion (http://.ace.cochrane.org/). ELIGIBILITY CRITERIA: New and updated versions of systematic reviews published up to 17 September 2015 were eligible. Protocols for systematic reviews were excluded. RESULTS: A total of 159 reviews were included. GRADE was used in 103 reviews (65%). Of these, high-level evidence for the primary outcome was identified in 11 reviews (10%). The main reasons that quality of evidence for the primary outcome was downgraded were risk of bias (n = 44; 43%) and imprecision (n = 36; 35%). Authors of 47% (n = 75) of the total number of reviews made conclusive statements about the effects of interventions. Independent predictors of conclusiveness in the subgroup of reviews with GRADE assessments were quality of evidence for the primary outcome (odds ratio 2.03; 95% confidence interval: [1.18 to 3.52] and an increasing number of studies included in reviews (OR 1.05; 95% CI: [1.01 to 1.09]). CONCLUSION: It was common for conclusive statements to be made about the effects of interventions despite evidence for the primary outcome being rated less than high quality. Improving methodological quality of trials would have the greatest impact on improving the quality of evidence.

The role of emotion in clinical decision making: an integrative literature review.

BACKGROUND: Traditionally, clinical decision making has been perceived as a purely rational and cognitive process. Recently, a number of authors have linked emotional intelligence (EI) to clinical decision making (CDM) and calls have been made for an increased focus on EI skills for clinicians. The objective of this integrative literature review was to identify and synthesise the empirical evidence for a role of emotion in CDM. METHODS: A systematic search of the bibliographic databases PubMed, PsychINFO, and CINAHL (EBSCO) was conducted to identify empirical studies of clinician populations. Search terms were focused to identify studies reporting clinician emotion OR clinician emotional intelligence OR emotional competence AND clinical decision making OR clinical reasoning. RESULTS: Twenty three papers were retained for synthesis. These represented empirical work from qualitative, quantitative, and mixed-methods approaches and comprised work with a focus on experienced emotion and on skills associated with emotional intelligence. The studies examined nurses (10), physicians (7), occupational therapists (1), physiotherapists (1), mixed clinician samples (3), and unspecified infectious disease experts (1). We identified two main themes in the context of clinical decision making: the subjective experience of emotion; and, the application of emotion and cognition in CDM. Sub-themes under the subjective experience of emotion were: emotional response to contextual pressures; emotional responses to others; and, intentional exclusion of emotion from CDM. Under the application of emotion and cognition in CDM, sub-themes were: compassionate emotional labour - responsiveness to patient emotion within CDM; interdisciplinary tension regarding the significance and meaning of emotion in CDM; and, emotion and moral judgement. CONCLUSIONS: Clinicians' experienced emotions can and do affect clinical decision making, although acknowledgement of that is far from universal. Importantly, this occurs in the in the absence of a clear theoretical framework and educational preparation may not reflect the importance of emotional competence to effective CDM.

Midazolam for sedation before procedures.

BACKGROUND: Midazolam is used for sedation before diagnostic and therapeutic medical procedures. It is an imidazole benzodiazepine that has depressant effects on the central nervous system (CNS) with rapid onset of action and few adverse effects. The drug can be administered by several routes including oral, intravenous, intranasal and intramuscular. OBJECTIVES: To determine the evidence on the effectiveness of midazolam for sedation when administered before a procedure (diagnostic or therapeutic). SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL to January 2016), MEDLINE in Ovid (1966 to January 2016) and Ovid EMBASE (1980 to January 2016). We imposed no language restrictions. SELECTION CRITERIA: Randomized controlled trials in which midazolam, administered to participants of any age, by any route, at any dose or any time before any procedure (apart from dental procedures), was compared with placebo or other medications including sedatives and analgesics. DATA COLLECTION AND ANALYSIS: Two authors extracted data and assessed risk of bias for each included study. We performed a separate analysis for each different drug comparison. MAIN RESULTS: We included 30 trials (2319 participants) of midazolam for gastrointestinal endoscopy (16 trials), bronchoscopy (3), diagnostic imaging (5), cardioversion (1), minor plastic surgery (1), lumbar puncture (1), suturing (2) and Kirschner wire removal (1). Comparisons were: intravenous diazepam (14), placebo (5) etomidate (1) fentanyl (1), flunitrazepam (1) and propofol (1); oral chloral hydrate (4), diazepam (2), diazepam and clonidine (1); ketamine (1) and placebo (3); and intranasal placebo (2). There was a high risk of bias due to inadequate reporting about randomization (75% of trials). Effect estimates were imprecise due to small sample sizes. None of the trials reported on allergic or anaphylactoid reactions. Intravenous midazolam versus diazepam (14 trials; 1069 participants)There was no difference in anxiety (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.39 to 1.62; 175 participants; 2 trials) or discomfort/pain (RR 0.60, 95% CI 0.24 to 1.49; 415 participants; 5 trials; I² = 67%). Midazolam produced greater anterograde amnesia (RR 0.45; 95% CI 0.30 to 0.66; 587 participants; 9 trials; low-quality evidence). Intravenous midazolam versus placebo (5 trials; 493 participants)One trial reported that fewer participants who received midazolam were anxious (3/47 versus 15/35; low-quality evidence). There was no difference in discomfort/pain identified in a further trial (3/85 in midazolam group; 4/82 in placebo group; P = 0.876; very low-quality evidence). Oral midazolam versus chloral hydrate (4 trials; 268 participants)Midazolam increased the risk of incomplete procedures (RR 4.01; 95% CI 1.92 to 8.40; moderate-quality evidence). Oral midazolam versus placebo (3 trials; 176 participants)Midazolam reduced pain (midazolam mean 2.56 (standard deviation (SD) 0.49); placebo mean 4.62 (SD 1.49); P < 0.005) and anxiety (midazolam mean 1.52 (SD 0.3); placebo mean 3.97 (SD 0.44); P < 0.0001) in one trial with 99 participants. Two other trials did not find a difference in numerical rating of anxiety (mean 1.7 (SD 2.4) for 20 participants randomized to midazolam; mean 2.6 (SD 2.9) for 22 participants randomized to placebo; P = 0.216; mean Spielberger's Trait Anxiety Inventory score 47.56 (SD 11.68) in the midazolam group; mean 52.78 (SD 9.61) in placebo group; P > 0.05). Intranasal midazolam versus placebo (2 trials; 149 participants)Midazolam induced sedation (midazolam mean 3.15 (SD 0.36); placebo mean 2.56 (SD 0.64); P < 0.001) and reduced the numerical rating of anxiety in one trial with 54 participants (midazolam mean 17.3 (SD 18.58); placebo mean 49.3 (SD 29.46); P < 0.001). There was no difference in meta-analysis of results from both trials for risk of incomplete procedures (RR 0.14, 95% CI 0.02 to 1.12; downgraded to low-quality evidence). AUTHORS' CONCLUSIONS: We found no high-quality evidence to determine if midazolam, when administered as the sole sedative agent prior to a procedure, produces more or less effective sedation than placebo or other medications. There is low-quality evidence that intravenous midazolam reduced anxiety when compared with placebo. There is inconsistent evidence that oral midazolam decreased anxiety during procedures compared with placebo. Intranasal midazolam did not reduce the risk of incomplete procedures, although anxiolysis and sedation were observed. There is moderate-quality evidence suggesting that oral midazolam produces less effective sedation than chloral hydrate for completion of procedures for children undergoing non-invasive diagnostic procedures.

Inadvertent Hypothermia After Procedural Sedation and Analgesia in a Cardiac Catheterization Laboratory: A Prospective Observational Study.

OBJECTIVES: To identify the prevalence of and risk factors for inadvertent hypothermia after procedures performed with procedural sedation and analgesia in a cardiac catheterization laboratory. DESIGN: A single-center, prospective observational study. SETTING: A tertiary-care private hospital in Australia. PARTICIPANTS: 399 patients undergoing elective procedures with procedural sedation and analgesia were included. Propofol infusions were used when an anesthesiologist was present. Otherwise, bolus doses of either midazolam or fentanyl or a combination of these medications was used. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Hypothermia was defined as a temperature<36.0°C. Multivariate logistic regression was used to identify risk factors. Hypothermia was present after 23.3% (n = 93; 95% confidence interval [CI] 19.2%-27.4%) of 399 procedures. Sedative regimens with the highest prevalence of hypothermia were any regimen that included propofol (n = 35; 40.2%; 95% CI 29.9%-50.5%) and the use of fentanyl combined with midazolam (n = 23; 20.3%; 95% CI 12.9%-27.7%). Difference in mean temperature from pre-procedure to post-procedure was -0.27°C (standard deviation 0.45). Receiving propofol (odds ratio [OR] 4.6 95% CI 2.5-8.6), percutaneous coronary intervention (OR 3.2; 95% CI 1.7-5.9), body mass index<25 (OR 2.5; 95% CI 1.4-4.4) and being hypothermic prior to the procedure (OR 4.9; 95% CI 2.3-10.8) were independent predictors of post-procedural hypothermia. CONCLUSIONS: A moderate prevalence of hypothermia was observed. The small absolute change in temperature observed may not be a clinically important amount. More research is needed to increase confidence in the authors' estimates of hypothermia in sedated patients and its impact on clinical outcomes.

Prevalence and predictors of opioid use before orthopaedic surgery in an Australian setting: A multicentre, cross-sectional, observational study.

Opioid analgesics are commonly used by patients awaiting orthopaedic surgery, and preoperative opioid use is associated with a greater burden of postoperative pain, suboptimal surgical outcomes and higher healthcare costs. This study aimed to examine the prevalence of total opioid use before elective orthopaedic surgery with a focus on regional and rural hospitals in New South Wales, Australia. This was a cross-sectional, observational study of patients undergoing orthopaedic surgery conducted between April 2017 and November 2019 across five hospitals that included a mix of metropolitan, regional, rural, private and public settings. Preoperative patient demographics, pain scores and analgesic use were collected during pre-admission clinic visits, held between two and six weeks before surgery. Of the 430 patients included, 229 (53.3%) were women and the mean age was 67.5 (standard deviation 10.1) years. The overall prevalence of total preoperative opioid use was 37.7% (162/430). Rates of preoperative opioid use ranged from 20.6% (13/63) at a metropolitan hospital to 48.8% (21/43) at an inner regional hospital. Multivariable logistic regression showed that the inner regional setting was a significant predictor of opioid use before orthopaedic surgery (adjusted odds ratio 2.6; 95% confidence interval 1.0 to 6.7) after adjusting for covariates. Opioid use prior to orthopaedic surgery is common and appears to vary by geographical location.

Prevalence and predictors of long-term opioid use following orthopaedic surgery in an Australian setting: A multicentre, prospective cohort study.

Opioid analgesics prescribed for the management of acute pain following orthopaedic surgery may lead to unintended long-term opioid use and associated patient harms. This study aimed to examine the prevalence of opioid use at 90 days after elective orthopaedic surgery across major city, regional and rural locations in New South Wales, Australia. We conducted a prospective, observational cohort study of patients undergoing elective orthopaedic surgery at five hospitals from major city, regional, rural, public and private settings between April 2017 and February 2020. Data were collected by patient questionnaire at the pre-admission clinic 2-6 weeks before surgery and by telephone call after 90 days following surgery. Of the 361 participants recruited, 54% (195/361) were women and the mean age was 67.7 years (standard deviation 10.1 years). Opioid use at 90 or more days after orthopaedic surgery was reported by 15.8% (57/361; 95% confidence interval (CI) 12.2-20%) of all participants and ranged from 3.5% (2/57) at a major city location to 37.8% (14/37) at an inner regional location. Predictors of long-term postoperative opioid use in the multivariable analysis were surgery performed at an inner regional location (adjusted odds ratio 12.26; 95% CI 2.2-68.24) and outer regional location (adjusted odds ratio 5.46; 95% CI 1.09-27.50) after adjusting for known covariates. Long-term opioid use was reported in over 15% of patients following orthopaedic surgery and appears to be more prevalent in regional locations in Australia.

Development and validation of the nursing confidence in managing sedation complications scale.

AIM: To develop the Nursing Confidence in Managing Sedation Complications Scale. DESIGN: A multi-phased approach was used. METHODS: An initial bank of items was created based on the authors' experience and clinical practice guidelines. An expert panel assessed content validity. Exploratory factor analysis was used for item reduction and regression was used to explore construct validity. Responsiveness was evaluated using a pre-test post-test design. RESULTS: Criteria for content validity was met for 34 items. An 18-item, three-factor solution was identified from exploratory factor analysis performed using Nursing Confidence in Managing Sedation Complications Scale scores from 228 nurses. Subscales accounted for 66% of the variance. Cronbach's alpha for the scale (0.95) and subscales was high (>0.85). There were differences (p < .001) in Nursing Confidence in Managing Sedation Complications Scale scores relative to years of experience and work environment. NC-MSCS scores increased significantly from before to after sedation training (mean difference = 31.8; 95% CI = 24.4-39; N = 31).

Midazolam for sedation before procedures in adults and children: a systematic review update.

BACKGROUND: Midazolam is used for sedation before diagnostic and therapeutic medical procedures by several routes including oral, intravenous, intranasal and intramuscular. This is an update of a Cochrane review published in 2016, which aimed to determine the evidence on the effectiveness of midazolam for sedation when administered before a diagnostic or therapeutic procedure in adults and children. METHODS: We searched CENTRAL, MEDLINE, Embase and two trials registers up to May 2020 together with reference checking to identify additional studies. We imposed no language restrictions. Randomized controlled trials of midazolam in comparison with placebo or other medications used for sedation were included. Two authors independently extracted data and assessed risk of bias for each included study. RESULTS: Eight new trials were included in this update, which resulted in changed conclusions for the intravenous midazolam versus placebo, oral midazolam versus chloral hydrate and oral midazolam versus placebo comparisons. Effect estimates for all outcomes within the intravenous midazolam versus placebo (7 trials; 633 adults and 32 children) are uncertain due to concerns about imprecision and risk of bias. Midazolam resulted in a higher level of sedation than placebo (mean difference (MD) 1.05; 95% confidence interval (95% CI) 0.69 to 1.41; 1 study; 100 adults). There was no difference in anxiety (RR 0.43, 95% CI 0.09 to 1.99; I2 = 75%; 2 studies; 123 adults). Risk of difficulty performing procedures was lower in the midazolam group (RR 0.5; 95% CI 0.29 to 0.86; I2 = 45%; 3 studies; 191 adults and 32 children). There was no difference in discomfort (RR 0.51; 95% CI 0.25 to 1.04; I2 = 0%; 2 studies; 190 adults). Five trials with 336 children were included in the oral midazolam versus chloral hydrate comparison. Midazolam was less likely to result in moderate sedation (RR 0.30, 95% CI 0.11 to 0.82; I2 = 64%; 2 studies, 228 participants). This effect estimate is highly uncertain due to concerns about the risk of bias, imprecision and inconsistency. There was no difference in ratings of anxiety (SMD - 0.26; 95% CI - 0.75 to 0.23; I2 = 0%; 2 studies; 68 participants). Midazolam increased risk of incomplete procedures (RR 4.01; 95% CI 1.92 to 8.40; I2 = 0%; 4 studies, 268 participants). This effect estimate is uncertain due to concerns about the risk of bias. There were four trials with 359 adults and 77 children included in the oral midazolam versus placebo comparison. Midazolam reduced ratings of anxiety (SMD - 1.01; 95% CI - 1.86 to - 0.16; I2 = 92%; 4 studies; 436 participants). It is unclear if midazolam has an effect on difficulty performing procedures. Meta-analysis was not performed because there was only one incomplete procedure in the midazolam group in one of the trials. Midazolam reduced pain in one study with 99 adults (MD - 2; 95% CI - 2.5 to - 1.6; moderate quality). The effect estimate is uncertain due to concerns about the risk of bias. CONCLUSION: The additional evidence arising from inclusion of new studies in this updated review has not produced sufficient high-quality evidence to determine whether midazolam produces more effective sedation than other medications or placebo in any specific population included in this review. For adults, there was low-quality evidence that intravenous midazolam did not reduce the risk of anxiety or discomfort/pain in comparison to placebo, but the sedation level was higher. By combining results from adults and children, there was low-quality evidence of a large reduction in the risk of procedures being difficult to perform with midazolam in comparison to placebo. The effect estimates for this comparison are uncertain because there was concern about risk of bias and imprecision. There is moderate-quality evidence suggesting that oral midazolam produces less-effective sedation than chloral hydrate for completion of procedures for children undergoing non-invasive diagnostic procedures. Ratings of anxiety were not different between oral midazolam and chloral hydrate. The extent to which giving oral midazolam to adults or children decreases anxiety during procedures compared with placebo is uncertain due to concerns about risk of bias and imprecision. There was moderate-quality evidence from one study that oral midazolam reduced the severity of discomfort/pain for adults during a brief diagnostic procedure in comparison with placebo.

Predicting Prolonged Apnea During Nurse-Administered Procedural Sedation: Machine Learning Study.

BACKGROUND: Capnography is commonly used for nurse-administered procedural sedation. Distinguishing between capnography waveform abnormalities that signal the need for clinical intervention for an event and those that do not indicate the need for intervention is essential for the successful implementation of this technology into practice. It is possible that capnography alarm management may be improved by using machine learning to create a "smart alarm" that can alert clinicians to apneic events that are predicted to be prolonged. OBJECTIVE: To determine the accuracy of machine learning models for predicting at the 15-second time point if apnea will be prolonged (ie, apnea that persists for >30 seconds). METHODS: A secondary analysis of an observational study was conducted. We selected several candidate models to evaluate, including a random forest model, generalized linear model (logistic regression), least absolute shrinkage and selection operator regression, ridge regression, and the XGBoost model. Out-of-sample accuracy of the models was calculated using 10-fold cross-validation. The net benefit decision analytic measure was used to assist with deciding whether using the models in practice would lead to better outcomes on average than using the current default capnography alarm management strategies. The default strategies are the aggressive approach, in which an alarm is triggered after brief periods of apnea (typically 15 seconds) and the conservative approach, in which an alarm is triggered for only prolonged periods of apnea (typically >30 seconds). RESULTS: A total of 384 apneic events longer than 15 seconds were observed in 61 of the 102 patients (59.8%) who participated in the observational study. Nearly half of the apneic events (180/384, 46.9%) were prolonged. The random forest model performed the best in terms of discrimination (area under the receiver operating characteristic curve 0.66) and calibration. The net benefit associated with the random forest model exceeded that associated with the aggressive strategy but was lower than that associated with the conservative strategy. CONCLUSIONS: Decision curve analysis indicated that using a random forest model would lead to a better outcome for capnography alarm management than using an aggressive strategy in which alarms are triggered after 15 seconds of apnea. The model would not be superior to the conservative strategy in which alarms are only triggered after 30 seconds.

Sequence analysis of capnography waveform abnormalities during nurse-administered procedural sedation and analgesia in the cardiac catheterization laboratory.

Identifying common patterns in capnography waveform abnormalities and the factors that influence these patterns could yield insights to optimize responses to sedation-induced respiratory depression. Respiratory state sequences for 102 patients who had a procedure in a cardiac catheterisation laboratory with procedural sedation and analgesia were developed by classifying each second of procedures into a state of normal breathing or other capnography waveform abnormalities based on pre-specified cut-offs for respiratory rate and end-tidal CO2 concentration. Hierarchical clustering identified four common patterns in respiratory state sequences, which were characterized by a predominance of the state assigned normal breathing (n = 42; 41%), hypopneic hypoventilation (n = 38; 38%), apnea (n = 15; 15%) and bradypneic hypoventilation (n = 7; 7%). A multivariable distance matrix regression model including demographic and clinical variables explained 28% of the variation in inter-individual differences in respiratory state sequences. Obstructive sleep apnea (R2 = 2.4%; p = 0.02), smoking status (R2 = 2.8%; p = 0.01), Charlson comorbidity index score (R2 = 2.5%; p = 0.021), peak transcutaneous carbon dioxide concentration (R2 = 4.1%; p = 0.002) and receiving an intervention to support respiration (R2 = 5.6%; p = 0.001) were significant covariates but each explained only small amounts of the variation in respiratory state sequences. Oxygen desaturation (SpO2 < 90%) was rare (n = 3; 3%) and not associated with respiratory state sequence trajectories.

Forced air warming during sedation in the cardiac catheterisation laboratory: a randomised controlled trial.

OBJECTIVE: Forced air warming (FAW) during general anaesthesia is a safe and effective intervention used to reduce hypothermia. The objective of this study was to determine if FAW reduces hypothermia when used for procedures performed with sedation in the cardiac catheterisation laboratory. METHODS: A parallel-group randomised controlled trial was conducted. Adults receiving sedation in a cardiac catheterisation laboratory at two sites were randomised to receive FAW or usual care, which involved passive warming with heated cotton blankets. Hypothermia, defined as a temperature less than 36°C measured with a sublingual digital thermometer after procedures, was the primary outcome. Other outcomes were postprocedure temperature, shivering, thermal comfort and major complications. RESULTS: A total of 140 participants were randomised. Fewer participants who received FAW were hypothermic (39/70, 56% vs 48/69, 70%, difference 14%; adjusted RR 0.75, 95% CI=0.60 to 0.94), and body temperature was 0.3°C higher (95% CI=0.1 to 0.5, p=0.004). FAW increased thermal comfort (63/70, 90% vs51/69, 74% difference 16%, RR 1.21, 95% CI=1.04 to 1.42). The incidence of shivering was similar (3/69, 4% vs 0/71 0%, difference 4%, 95% CI=-1.1 to 9.8). One patient in the control group required reintervention for bleeding. No other major complications occurred. CONCLUSION: FAW reduced hypothermia and improved thermal comfort. The difference in temperature between groups was modest and less than that observed in previous studies where use of FAW decreased risk of surgical complications. Therefore, it should not be considered clinically significant. TRIAL REGISTRATION NUMBER: ACTRN12616000013460.