Factorial validity and measurement invariance of the Athlete Burnout Questionnaire (ABQ)

The Athlete Burnout Questionnaire (ABQ) is the gold standard measure for burnout in athletes. However, previous assessments of factorial validity have: (a) tested overly restrictive measurement models; (b) provided mixed support for factorial validity; and (c) not been applied to assess measurement invariance across gender, sport type, or age. To address these issues, we used ABQ data provided by 914 athletes (Mage = 21.75 years, SD = 8.79) and examined factorial validity using confirmatory factor analysis (CFA) and exploratory structural equation modelling (ESEM) techniques. We also examined measurement invariance of the ABQ data across reported gender (female, male), sport type (individual, team), and age (≤18 years, >18 years) groups. The analyses revealed that an ESEM model provided superior fit over the corresponding CFA model. In terms of measurement invariance, support was provided for the equivalence of the ABQ across each group. This means that researchers using the ABQ can collect data across these groups and examine potential differences with confidence that the ABQ is approximately invariant. In all, we provide evidence that the majority of ABQ items are key target construct indicators and the burnout construct (as measured by the ABQ) has the same structure and meaning to different athlete groups.

Psychometric properties of the Cystic Fibrosis Eating Attitudes and Behaviours scale (CFEAB) in an adult population

OBJECTIVES

Individuals with Cystic Fibrosis (CF) may be at an increased risk of developing a range of eating difficulties. Scales designed to measure disordered eating in the general population do not cover CF-specific behaviours resulting in a knowledge gap. The CFEAB was developed as a CF-specific measure assessing eating behaviours and attitudes however little evidence exists regarding its psychometric quality. The aim of this cross-sectional study was to provide a robust assessment of its internal consistency, structural validity, and criterion validity.

METHODS

One-hundred and thirty-two people with CF completed self-report scales pertaining to mental health, eating disorders, and the Cystic Fibrosis Eating Attitudes and Behaviours (CFEAB).

RESULTS

Results of exploratory structural equation modelling indicated that a three-factor structure produced good fit with the 24-item CFEAB but a purified 12-item CFEAB displayed superior fit and internal consistency. Also, the 12-item scale predicted significant amounts of variance for anxiety, depression, and eating disorders showing enhanced relevance for clinical use. Conclusions These findings add emphasis to the importance of the validation and development of CF-specific measures and the possible inclusion at clinics to help improve CF patient care.

Don't look back in anger: A cross-sectional and dyadic examination of the Dark Triad, anger, and aggression in athletes

OBJECTIVES

The Dark Triad (psychopathy, Machiavellianism, and narcissism) has been linked to anti-social behaviour in sport, and while anti-social behaviour often involves aggression and violence, no research to date has examined the relationship between the Dark Triad and anger and aggression in athletes. The current two-sample study sought to address this gap.

DESIGN

Multi-sample cross-sectional design.

METHOD

Sample 1 included 224 athletes (MAGE = 23.85) and Sample 2 included 98 coach-athlete dyads (196 total; athlete MAGE = 18.15, coaches MAGE = 34.84). In both samples, facets of the Dark Triad were related to anger and aggression.

RESULTS

In Sample 1, regression analyses indicated that psychopathy positively predicted both anger and aggression and Machiavellianism positively predicted aggression. In Sample 2, actor-partner interdependence models indicated a combination of dyadic relationships (i.e., both actor [coach and athlete personality predicted their own anger and aggression] and partner effects [coach and athlete personality predicted the other's anger and aggression]). In this regard, actor effects were found between psychopathy and both anger and aggression and narcissism and aggression. Coach to athlete partner effects were found for narcissism and anger and Machiavellianism and aggression.

CONCLUSIONS

Overall, the findings provide evidence for personal and interpersonal relationships between the Dark Triad and anger and aggression and highlight the potential for the darker side of both athlete and coach personality to influence athlete emotions.

Explaining individual differences in cognitive performance: The role of anxiety, social support and living arrangements during COVID-19

The present study investigated the relationship between anxiety, social support, living arrangements and cognitive performance of university students during the global pandemic. Two hundred and fifteen students participated by completing online questionnaires. Separate moderated multiple regression models were used to test whether social support (Family, Friends, Significant Other subscales of the Multidimensional Scale of Perceived Social Support) moderated the relationship between anxiety (Anxiety subscale of Depression, Anxiety Stress Scale), living arrangements (Living Alone vs Living with Friends and Family) and cognitive performance (Cognitive Failures Questionnaire), after controlling for comorbid depression. The results for each level of perceived social support suggested that anxiety was negatively associated with cognitive performance. Our most significant finding was that for students living alone, social support from a significant other offered a protective factor, whereby buffering the anxiety related cognitive deficits prevalent in those who reported lower social support. These data have important practical implications for supporting the social-emotional and academic needs of university students during the global pandemic.

Inhibitory Control Across Athletic Expertise and Its Relationship With Sport Performance

Inhibitory control may be vital in elite sport. The authors examined the link between athletic expertise, inhibitory control, and sport performance in a two-part quasi experiment. Inhibitory control was indexed using the Stop-Signal Task, athlete expertise was categorized on literary recommendations, and sport performance was assessed using athlete and coach ratings. Study 1 examined cross-sectional and longitudinal patterns of inhibitory control across athletic expertise. Study 2 investigated whether the inhibitory control-sport performance relationship was moderated by expertise. Study 1 showed that expertise was linked to greater inhibitory control cross-sectionally and longitudinally. Study 2 revealed that expertise was related to superior performance on the Stop-Signal Task and athlete and coach performance ratings, and this relationship was moderated by athletic expertise. Inhibitory control relates to sport performance, increases with greater athlete expertise, and develops longitudinally. Long-term participation in sport may bring about changes in inhibitory control, which may lead to improved sport performance.

Emotional Intelligence Training: Influence of a Brief Slow-Paced Breathing Exercise on Psychophysiological Variables Linked to Emotion Regulation

Designing emotional intelligence training programs requires first testing the effectiveness of techniques targeting its main dimensions. The aim of this study was to investigate the effects of a brief slow-paced breathing (SPB) exercise on psychophysiological variables linked to emotion regulation, namely cardiac vagal activity (CVA), as well as perceived stress intensity, emotional arousal, and emotional valence. A total of 61 participants completed a 5-min SPB exercise and a control condition of a 5-min rest measurement. CVA was indexed with the root mean square of successive differences (RMSSD). Participants were also asked to rate their perceived stress intensity, emotional arousal, and emotional valence. Results showed that CVA was higher during SPB in comparison to the control condition. Contrary to our hypothesis, perceived stress intensity and emotional arousal increased after SPB, and perceived emotional valence was less positive after SPB. This could be explained by experiencing dyspnea (i.e., breathing discomfort), and the need to get acclimatized to SPB. Consequently, we may conclude that although physiological benefits of SPB on CVA are immediate, training may be required in order to perceive psychological benefits.

Executive Function and Mood: The Moderating Role of Athletic Expertise

Executive function (EF) is known to be influenced by mood, but whether this relationship holds for populations of athletes and whether athletic expertise moderates it is uncertain. Thus, in the current study, we examined relationships between positive and negative affect (i.e., mood), the lower-order cortical aspects of executive function (i.e., inhibition, shifting and updating), and athletic expertise. A sample of 256 participants (55.08% male; M_age = 20.69) completed a self-report mood measure and computerized tests of EF. Individuals with more athletic expertise reported higher positive affect and better EF scores, whereas those with less athletic expertise reported higher negative affect. Structural equation modelling indicated that positive affect was related to better inhibition, shifting, and updating performance but was not related to performance errors. Similarly, negative affect was related to better EF, except for the inhibition latency score. Athletic expertise moderated all significant associations between mood and EF and higher expertise facilitated higher EF performance. Together, athletic expertise is an important individual differences factor in understanding the influence of mood on EF performance.

Reflection-impulsivity in athletes: A cross-sectional and longitudinal investigation

Reflection-impulsivity is a dimension of cognitive or decision-making style. We conducted two quasi-experimental studies to examine reflection-impulsivity in athletes using an information sampling task. In Study 1 (n = 108; M_age= 22.7 ± SD_age = 1.42; 50% female), we used a cross-sectional design to compare performance across athletic expertise (super-elite, elite, amateur, novice or non-athlete) and sport type (external-paced or self-paced). In Study 2 (Time 1 n = 106; M_age= 21.32 ± SD_age = 5.77; 53% female and Time 2 n = 64; M_age= 21.19 ± SD_age = 5.12; 44% female), we examined changes in reflection-impulsivity across a 16-week playing season. Study 1 showed more accurate and more efficient performance as athletic expertise increased. Study 2 revealed better effectiveness and efficiency following sport participation, a 16-week playing season, most notably in elite-level performers. No sport-type differences were noted. Taken together, the studies demonstrate an association between reflection-impulsivity and athletic expertise, while also providing evidence that competitive sports participation leads to efficient decisions based on reflection, without sacrificing accuracy, which is often a consequence of impulsive decision-making.

The effect of trait emotional intelligence on working memory across athletic expertise

Research attests to the important contributions of emotional, athletic, and cognitive expertise for sport performance. However, little is known regarding the interplay between trait emotional intelligence, athletic expertise, and working memory. The aim of this research was to examine the interplay between working memory (emotional, capacity and ability), trait emotional intelligence and athletic expertise. In total, 437 participants aged between 18 and 27 years with a range of athletic expertise (i.e., non-athlete n = 96, novice n = 92, amateur n = 85, elite n = 83, and super-elite n = 81) completed the Trait Emotional Intelligence Questionnaire Short Form, an Emotion Recognition Task (i.e., working memory-emotional), a Spatial Span Task (i.e., working memory-capacity), and a Spatial Working Memory Test (i.e., working memory-ability). Structural equation modelling indicated a significant positive relationship between trait emotional intelligence and all three components of working memory (i.e., emotional, capacity and ability). Also, this differed over athletic expertise whereby those with more expertise reported larger effects than those with less expertise. These findings suggest that trait emotional intelligence is important for working memory in athletes. Moreover, the link between cognitive and affective processes are increasingly relevant as athletes develop expertise levels.

Mental Health Measurement in a Post Covid-19 World: Psychometric Properties and Invariance of the DASS-21 in Athletes and Non-athletes

Psychological science faces a call to action researching the implications of the corona virus disease 2019 (Covid-19) pandemic. Rapid reviews have reported that maintaining rigorous research standards is a priority for the field, such as ensuring reliable and valid measurement, when investigating people’s experience of Covid-19 (O’Connor et al., 2020). However, no research to date has validated a measure mental health symptomology for an athlete population. The current research addresses this gap by examining the internal consistency, factor structure, invariance, and convergent validity of the Depression Anxiety and Stress Scale (DASS-21; Lovibond and Lovibond, 1995) in two athlete samples. Participants completed the DASS-21 and sport-specific measures of mental health such as the Profile of Mood States – Depression subscale (POMS-D), Sport Anxiety Scale-2 (SAS-2), Athlete Burnout Questionnaire (ABQ), and Athlete Psychological Strain Questionnaire (APSQ). In sample one (n = 894), results of exploratory structural equation modeling indicated that a three-factor model provided good fit to the data, but a bifactor model provided better fit. Factor loadings indicated minimal misspecification and higher loadings on the general-factor. Invariance testing suggested equivalence across gender, athletic expertise, sport type, and injury status. Further, latent mean differences analyses indicated that females and injured athletes scored higher than male and non-injured athletes on all DASS-21 factors reporting higher mental health symptomology, those with more expertise scored higher on the general-factor and depression and those with less expertise scored higher on anxiety and stress, and no differences between team and individual athletes. In sample two (n = 589), the bifactor structure was replicated. Results largely supported the scales convergent validity with depression predicting POMS-D scores, whereas all three subscales predicted the SAS-2, ABQ, and APSQ scores. Internal consistency was acceptable in both samples. The current work provides initial support for use of the DASS-21 as an operationalisation of mental health symptomology in athletes. Theoretical and practical implications of these results are discussed.

The winner takes it all: The mediating role of competitive orientations in the Dark Triad and sport task performance relationship

The Dark Triad traits (Machiavellianism, narcissism, and psychopathy) are prevalent in athletes. However, currently, we do not know whether the Dark Triad confers any competitive advantages in sport. To address this issue, the present study had two aims. First, to examine whether the Dark Triad predicted task performance in a basketball free throw task. Second, to examine whether competitive orientations explained (i.e. mediated) this relationship. A sample of 189 athletes (mean age = 19.11 years) completed measures of the Dark Triad, competitive orientations, and task performance (basketball free throw task). Regression analyses indicated that the Dark Triad predicted better task performance. In addition, mediation analyses indicated that the Dark Triad-performance relationship was explained by both hypercompetitive and self-developmental competitive orientations. The present study provides the first evidence that the Dark Triad may lead to better task performance in sport, and that this effect may be driven by athletes' competitive orientations.

Attention, working-memory control, working-memory capacity, and sport performance: The moderating role of athletic expertise

The aim of this research was to detangle the association between attention, working-memory (focusing on both control and capacity functions), and sport performance across athletic expertise. Specifically, the mediating effect of working-memory-control and working-memory-capacity on the attention and performance relationship will be investigated, and whether this effect differs across athlete expertise. A sample of 359 athletes (M_age = 18.91 ± SD = 1.01; 54.87% male) with a range of athletic expertise (novice n = 99, amateur n = 92, elite n = 87, and super-elite n = 81) completed a battery of neurocognitive tasks assessing attention, working-memory-control, working-memory-capacity, and a cognitively engaging motor task (e.g. basketball free-throw task). Athletes with more expertise performed better on tasks of attention, working-memory-control and working-memory-capacity. Results of structural equation modelling indicated a positive association between the cognitive measures and sport performance. Specifically, working-memory-control and working-memory-capacity mediated the attention and sport performance relationship. Additionally, invariance testing indicated larger effects for those with more athletic expertise. These findings provide a better understanding of how attention and the control and capacity functions of working-memory interact to predict performance. Theoretical and practical implications of these results are discussed.

Airway management before, during and after extubation: a survey of practice in the United Kingdom and Ireland

Summary Complications at extubation remain an important risk factor in anaesthesia. A postal survey was conducted on extubation practice amongst consultant anaesthetists in the United Kingdom and Ireland. The use of short acting drugs encourages anaesthetists to extubate the trachea at lighter levels of anaesthesia. The results show that oxygen (100%) is not routinely administered either before extubation or en route to the recovery area. A trend towards a head up or sitting position at extubation is emerging. However, further research into the use of these positions is required. Airway related complications at extubation are relatively frequent but are usually dealt with by simple basic measures. The role of drugs such as propofol in decreasing the incidence of these complications needs further evaluation. Some of these results give concern for patient safety and for training. The importance of teaching and adherence to continued oxygenation until complete recovery is strongly emphasised. Nerve stimulators should be used continually as standard monitoring throughout the anaesthetic period when muscle-relaxing drugs are part of the anaesthetic technique.

Changes in cerebral oxygenation during cold (28 degrees C) and warm (34 degrees C) cardiopulmonary bypass using different blood gas strategies (alpha-stat and pH-stat) in patients undergoing coronary artery bypass graft surgery

BACKGROUND

Impaired cerebral oxygenation, which is reflected by measuring jugular bulb oxygenation, is thought to play an important role in the development of neurological injury after cardiac operations with cardiopulmonary bypass (CPB). The effects of cardiopulmonary temperature and blood gas strategy on cerebral oxygenation are not fully appreciated.

METHODS

Sixty patients were randomly allocated into four equal groups (cold alpha-stat, cold pH-stat, warm alpha-stat and warm pH-stat) to compare the effect of these perfusion strategies on cerebral oxygenation monitored by jugular bulb oximetry [jugular bulb oxygen saturation (SjO(2)) and arterial-jugular bulb oxygen content difference (AjDO(2))]. Jugular bulb oxygen saturation and AjDO(2) were measured before CPB, after 5, 20, 40 min on CPB, at start and end of rewarming, 5 min before the end of CPB and 10 min after CPB. Two-way analysis of variance was used to model the lowest SjO(2) and highest AjDO(2) during CPB, with CPB temperature and blood gas management as contributing factors.

RESULTS

Significant changes in SjO(2) were only related to the type of blood gas management, with no significant difference between warm and cold CPB patients. In addition, during rewarming, desaturation (SjO(2) </= 50%) occurred in seven patients of 30 in the alpha-stat groups and in one patient of 30 in the pH-stat groups (P = 0.021), and in five patients of 30 in the cold groups vs. three of 30 in the warm groups (P = 0.434). However, no significant changes were found in the highest AjDO(2) between the four groups.

CONCLUSION

Cold CPB failed to offer any further brain protection in terms of better preservation of cerebral oxygenation than warm CPB. Therefore, warm CPB (34 degrees C) with different blood gas strategies appears to be a satisfactory alternative to cold CPB (28 degrees C).

A comparison of the forces exerted during laryngoscopy using disposable and non-disposable laryngoscope blades

The concern that re-usable equipment may be a source of cross-infection has prompted the increased use of disposable laryngoscope blades. We conducted a study investigating the duration of laryngoscopy and the peak force generated using various laryngoscope blades. Five blades were studied: one reusable Macintosh 3 blade, one disposable metal blade and three plastic disposable blades. Sixty anaesthetists performed laryngoscopy on a mannequin using each of the five blades presented in a random order. This was then repeated with a rigid collar applied to the mannequin. The mean force applied with the collar off with the metal blades was 32.8 and 30.8 N, and with the plastic blades 37.3, 39.6 and 41.5 N, respectively (p < 0.0001). The mean force applied with the collar on with the metal blades was 30.5 and 32.5 N, and with the plastic blades 35.5, 34.9 and 31.4 N, respectively (p < 0.0001). The mean duration of laryngoscopy with the collar off for the metal blades was 5.6 and 5.4 s, and with the plastic blades 10, 7.2 and 7.5 s (p < 0.0001). The duration of laryngoscopy with the collar applied for the metal blades was 7.1 and 7.5 s, and with the plastic blades 11.8, 9.7 and 9.0 s (p < 0.0001). The use of plastic blades results in both greater peak force and duration of laryngoscopy.

An unusual case of stridor after thyroidectomy

Twelve days after subtotal thyroidectomy, an air pocket developed in a patient's neck. The pressure in this pocket had gradually increased as small amounts of air, probably associated with coughing, came out of a tiny hole in the trachea to form a pneumocoele. This produced limited surgical emphysema, causing venous congestion and oedema of the soft tissues of the larynx, which in turn led to increasing airway obstruction. We believe that this is the first reported case of a pneumocoele that gradually increased in size, causing airway obstruction that was almost certainly due to secondary laryngeal oedema.

Survey of the use of the gum elastic bougie in clinical practice

Data were collected prospectively on the use of the gum elastic bougie in 200 patients. The bougie was successfully inserted into the trachea and tracheal intubation was accomplished in 199 cases. The bougie was inserted into the trachea at the first attempt in 178 cases. In nine cases (4.5%) a second, more experienced, clinician was required. In 173 cases, the grades of view were recorded before and after the application of laryngeal pressure; pressure improved the view in 80 cases (46%), had no effect in 89 (51%) and worsened the view in four cases (2%). Various recommendations for optimal external laryngeal pressure and use of the bougie were not followed on 15-64% of occasions. There is a need for better education in these techniques.

Anions and the anaesthetist

Anions are the negative components of most chemical structures and play many important physiological and pharmacological roles that are of interest to the anaesthetist. Their relevance is reviewed with a particular emphasis on the inorganic anions (halides, bicarbonate, phosphate and sulphate) and the significance and limitations of the anion gap. Organic anions (albumin, lactate) are also discussed, albeit briefly. The suitability of anions for their role in neurotransmission and acid-base balance is outlined.

Changes in serum S100beta protein and Mini-Mental State Examination after cold (28 degrees C) and warm (34 degrees C) cardiopulmonary bypass using different blood gas strategies (alpha-stat and pH-stat)

BACKGROUND

The effect of cardiopulmonary bypass temperature and blood gas management on the brain is still controversial. This study was designed to compare the changes in S100beta protein concentration and Mini-Mental State Examination in patients undergoing cold (28 degrees C) vs. warm (34 degrees C) cardiopulmonary bypass using different blood gas strategies (alpha-stat and pH-stat).

METHODS

Sixty patients were randomly allocated to one of four equal groups (cold alpha-stat, cold pH-stat, warm alpha-stat, warm pH-stat). Serum S100beta concentrations were measured before CPB, directly after CPB, at 4.5 h and at 24 h after CPB. Mini-Mental State Examination was performed one day before surgery and on day five after the operation. Antegrade warm blood cardioplegia (37 degrees C) was used in all patients.

RESULTS

There was no significant difference in postoperative S100beta protein levels between the four groups. Also, there was no interaction between bypass temperature and type of blood gas strategy on S100beta levels after bypass (directly after bypass, 4.5 h and 24 h after bypass). Mini-Mental State Examination score was not affected by blood gas strategy but it was significantly lower in patients undergoing cold cardiopulmonary bypass surgery: median (range), 26 (12-29) vs. 27 (23-30) in warm patients, P = 0.014. There was no significant correlation between Mini-Mental State Examination score 5 days after CPB and S100beta levels at any of the studied time-points after CPB.

CONCLUSION

These results support the use of warm CPB (34 degrees C) in patients undergoing coronary artery bypass surgery regardless of the type of blood gas strategy.

Spatially resolved spectroscopy (NIRO-300) does not agree with jugular bulb oxygen saturation in patients undergoing warm bypass surgery

PURPOSE

Near infrared spectroscopy (NIRS) is a promising non-invasive method for continuous monitoring of cerebral oxygenation during cardiac surgery with cardiopulmonary bypass (CPB). This study was designed to study the agreement between tissue oxygen index (TOI) measured by spatially resolved spectroscopy (NIRO-300) and jugular bulb oxygen saturation (SjO2) in patients undergoing warm coronary bypass surgery.

METHODS

Seventeen patients undergoing warm coronary artery bypass surgery were studied. NIRS was continuously monitored and was averaged before CPB, five, 20, 40, 60 min on CPB, five minutes before end of CPB and ten minutes after CPB to coincide with SjO2 measurements. Bypass temperature was maintained at 34-37 degrees C.

RESULTS

Bland and Altman analysis showed a bias (TOI-SjO2) of -6.7%, and wide limits of agreement (from 16% to -28%) between the two methods. In addition, mean TOI was lower than mean SjO2 during and after CPB. We observed a statistically significant correlation between arterial carbon dioxide and SjO2 measurements (r2=0.33; P=0.0003), but the former did not correlate with TOI values (r2=0.001; P=0.7).

CONCLUSION

Our results demonstrate a lack of agreement between SjO2 and TOI for monitoring cerebral oxygenation during cardiac surgery. We conclude that the two methods are not interchangeable.

Changes in jugular bulb oxygenation in patients undergoing warm coronary artery bypass surgery (34-37 degrees C)

BACKGROUND AND OBJECTIVE

Imbalance between cerebral oxygen supply and demand is thought to play an important role in the development of cerebral injury during cardiac surgery with cardiopulmonary bypass.

METHODS

We studied jugular bulb oxygen saturation, jugular bulb oxygen tension, arterial-jugular bulb oxygen content difference and oxygen extraction ratio in 20 patients undergoing warm coronary artery bypass surgery (34-37 degrees C) with pH-stat blood gas management.

RESULTS

Only two patients showed desaturation (jugular bulb oxygen saturation < 50%) at 5 min on bypass, and none from 20 min onwards. Multiple regression models were performed after using bypass temperature, mean arterial pressure, cerebral perfusion pressure, haemoglobin concentration and arterial carbon dioxide tension as independent variables, and arterial-jugular bulb oxygen content difference, jugular bulb oxygen saturation, oxygen extraction ratio and jugular bulb oxygen tension as individual dependent variables.

CONCLUSIONS

We found that jugular bulb oxygen saturation, jugular bulb oxygen tension and oxygen extraction ratio are mainly dependent on arterial carbon dioxide tension, and arterial-jugular bulb oxygen content difference is dependent on arterial carbon dioxide tension and the bypass temperature. Our results suggest jugular bulb oxygenation is mainly dependent on arterial carbon dioxide tension during warm cardiopulmonary bypass.

Evaluation of the use of the Flexiblade

The Flexiblade is a laryngoscope which has a 'flexible' blade. The 'front' half of the blade can be moved in an anterior direction during laryngoscopy, enhancing the view of the glottis. The degree of movement can be controlled with the lever. We studied 200 ASA 1 and 2 adult patients requiring tracheal intubation and the patients acted as their own controls. The view of the larynx was improved in 93% of the cases when the vocal cords were not completely visible at laryngoscopy with the lever in the neutral position. Ninety-seven per cent of patients with a Cormack and Lehane grading of 2 at normal laryngoscopy were transformed to grade 1 when the lever of the Flexiblade was depressed and 84% of cases with a grading of 3 were transformed to grade 2 or 1. In four patients, there was deterioration in the view of the cords: three patients with grade 1 were transformed to grade 2 and one with grade 2 to grade 3. There was no improvement in one case with grade 2 and three with grade 3.

Early release pattern of S100 protein as a marker of brain damage after warm cardiopulmonary bypass

Warm blood cardioplegia may be more beneficial to the heart than cold cardioplegia, but the effects of warm cardiopulmonary bypass and warm blood cardioplegia on the brain are controversial. S100 protein is an early marker of brain damage and has been detected after cold cardiopulmonary bypass. We studied S100 concentrations in 20 patients undergoing coronary artery bypass surgery before and after warm cardiopulmonary bypass (34-37 degrees C) using warm blood cardioplegia (37 degrees C) for all patients. The peak level of S100 protein occurred immediately after warm cardiopulmonary bypass, then decreased progressively until the last measurement at 4.5 h after bypass. The peak level appears to be dependent upon the age of the patient, with the following regression equation: y = -3.2 + 0.08x, where y is S100 protein concentration in microg.l-1 and x is patient age in years. Further studies are needed to investigate the clinical significance of this early release pattern. Patient age should be taken into account when studying S100 protein levels after cardiopulmonary bypass.

Calcium and the anaesthetist

Calcium plays a central role in a large number of physiological actions that are essential for life. It is important therefore that the anaesthetist understands calcium pathophysiology. In this review, the physiology, regulation, clinical features, causes and treatment of alterations in circulating calcium will be discussed. In addition, the effects that acid-base status, massive blood transfusion and cardiopulmonary bypass may have on circulating calcium will be highlighted. Finally, the role that calcium plays in ischaemic/reperfusion injury and myocardial stunning will be summarised.

Acute cardiac herniation after radical pleuropneumonectomy

Acute cardiac herniation after radical pneumonectomy is extremely rare and is associated with an immediate mortality greater than 50%. We report a patient in whom cardiac herniation produced no signs or symptoms. The heart was returned to its correct position and the pericardial defect was repaired.

The use of breathing system filters as oxygen-delivery devices

A breathing system filter can remain connected to a laryngeal mask airway during recovery from anaesthesia. The Luer-lock monitoring port on the filter could be used for the delivery of supplementary oxygen. The efficacy of this technique was assessed in vitro by comparing the performance of two filters with four other devices, including a T-piece with a 40% oxygen injector. The minimum inspired oxygen fraction and pressure drop were measured over a range of ventilatory conditions and oxygen flows. The minimum inspired oxygen fraction measured with the remaining devices was greater than with the T-piece at an oxygen flow of 10 l.min-1. The pressure drop was greater with the breathing system filters than with the T-piece. A potential advantage in using filters is that no additional equipment is required. However, if using the filters as oxygen supplementation devices, there is only one port open to the atmosphere in the system and inadvertent obstruction of this port could cause barotrauma. It must be remembered that the nonstandard use of such equipment contravenes the recently introduced Medical Device Directive regulations.

The cuffed oropharyngeal airway. Its clinical use in 100 patients

We studied the efficacy of the cuffed oropharyngeal airway in 100 patients. Insertion of the airway after induction of anaesthesia with propofol was easy in 95 of 100 patients, moderately difficult in four patients and failed in one patient. Complications, such as coughing, gagging or body movement, occurred during induction and insertion in 15 patients. Insertion of the airway was not associated with tachycardia or hypertension. Manual ventilation through the airway was easy in less than 30% of patients immediately after insertion. Manual ventilation became easier after adjusting the position of the patient's head, neck or jaw. During spontaneous breathing, adjustment of the head, neck or jaw was required in 30% of patients. Complete airway obstruction occurred in one patient after insertion of the device and in two patients during maintenance of anaesthesia. The airway was left in place during emergence from anaesthesia in the remaining 97 patients. No complications occurred in 91 patients and coughing occurred in the remaining six patients before or during removal of the airway. No regurgitation, vomiting or laryngospasm occurred in any patient at any time. Therefore, the cuffed oropharyngeal airway has a potential use in anaesthetised patients who are breathing spontaneously.

Respiratory complications associated with tracheal intubation and extubation

We conducted a prospective survey on the incidence of respiratory complications associated with tracheal intubation and extubation in 1005 patients who underwent elective general anaesthesia over a 4-month period. During induction of anaesthesia, respiratory complications occurred in 46 patients (4.6%; 95% confidence limits (CL): 3.3, 5.9%). The common complications were coughing (1.5%) and difficult ventilation through a facemask (1.4%). Tracheal intubation was difficult in eight patients (0.8%). Complications occurred immediately after tracheal extubation in 127 patients (12.6%; 95% CL: 10.6, 14.7) and in the recovery room in 95 patients (9.5%; 95% CL: 7.6, 11.3%). The common complications immediately after extubation were coughing (6.6%) and oxygen desaturation (SaO2 < 90%) (2.4%), and in the recovery room, airway obstruction (3.8%) and coughing (3.1%). The incidence of complications was significantly higher immediately after tracheal extubation than during induction of anaesthesia (P << 0.001). Even when all incidents of coughing that occurred after tracheal extubation were disregarded as a complication, the overall incidence was still higher immediately after extubation (7.4%) than during induction of anaesthesia (P < 0.01). We conclude that the incidence of respiratory complications associated with tracheal extubation may be higher than that during tracheal intubation.

Respiratory complications associated with tracheal extubation. Timing of tracheal extubation and use of the laryngeal mask during emergence from anaesthesia

Sixty patients were randomly allocated to one of three groups and the incidences of respiratory complications which occurred during emergence from anaesthesia were compared under the following three circumstances: tracheal extubation after the patient had regained consciousness (awake group); tracheal extubation while the patient was still anaesthetised (anaesthetised group); and the use of the laryngeal mask during emergence from anaesthesia (mask group). In the mask group, the laryngeal mask was inserted under deep anaesthesia before tracheal extubation and the lungs were ventilated through the laryngeal mask after tracheal extubation. In the awake group, straining (bucking) occurred in 18 patients and desaturation (arterial oxygen haemoglobin saturation < 95%) in two patients. In the anaesthetised group, airway obstruction occurred in 17 patients and desaturation in one of these patients. In the mask group, ventilation through the laryngeal mask was temporarily difficult immediately after tracheal extubation in one patient and coughing occurred before removal of the mask in three patients. No respiratory complications occurred in two patients in the awake group, three patients in the anaesthetised group and 16 patients in the mask group. The incidence of respiratory complications during recovery from anaesthesia was significantly lower in the mask group than in the other two groups (pooled) (p << 0.001). Therefore, the use of the laryngeal mask after tracheal extubation decreases the incidence of respiratory complications during recovery from anaesthesia.

Ease of insertion of the laryngeal mask airway by inexperienced personnel when using an introducer

The Portex introducer for the laryngeal mask airway was designed as an aid to successful insertion, acting as an idealised 'artificial hard palate' to guide the tip of the laryngeal mask into the correct position. A number of authors have investigated laryngeal mask insertion by unskilled personnel in certain situations, one example being nurses during in-hospital cardiopulmonary resuscitation. We investigated whether the introducer had any effect on the incidence of first-time successful LMA placement by unskilled personnel. These were nonanaesthetist doctors, randomly assigned to have one attempt at LMA insertion in an anaesthetised patient, with and without the introducer. In 44 patients with the LMA being inserted according to the manufacturer's instructions, there was a 68% success rate (14 failures). In 45 patients with the LMA being inserted with the aid of a Portex introducer, there was a 96% success rate (two failures). This was a highly significant improvement (p < 0.001).

Effect of the size of a tracheal tube and the efficacy of the use of the laryngeal mask for fibrescope-aided tracheal intubation

We randomly allocated 60 patients with normal airways into three groups to compare the ease of fibrescope-aided tracheal intubation using 8.0-mm internal diameter (group F8) and 6.0-mm (group F6) reinforced tracheal tubes and to evaluate the efficacy of the laryngeal mask as an aid for fibreoptic tracheal intubation (group L). In group F8 tracheal intubation was optimal in 2 of 20 patients and in two patients in whom intubation over the fibrescope was difficult the attempts resulted in inadvertent oesophageal intubation. In group F6 intubation was always successful and significantly easier than in group F8 (p < 0.005; 95% confidence interval for the difference in the proportion of the optimal intubation grade: 20-70%). In group L tracheal intubation was optimal in 18 of 20 patients and easier than in group F6 (p = 0.014; 95% confidence interval for difference: 10-60%). In both groups F6 and L tracheal intubation was completed within less than about 1 min. We conclude that conventional fibrescope-aided tracheal intubation with a 6.0-mm tracheal tube is easier than with an 8.0-mm tube and that the laryngeal mask facilitates fibrescope-aided tracheal intubation.

Effect of clonidine on gastric emptying of liquids

We have investigated the effects of clonidine on gastric emptying of liquids in 30 patients. In a double-blind, randomized design, clonidine 150 micrograms, morphine 10 mg or saline in 1 ml was given i.m. One hour later, the patient drank a paracetamol solution (1.5 g in 50 ml water). Venous blood samples were obtained every 15 min for 90 min thereafter. Plasma paracetamol concentrations were measured using high-pressure liquid chromatography and the area under the concentration-time curve was calculated. The degree of sedation and complications were recorded. The area under the curve for 0-60 min was significantly smaller in the morphine group than in the saline group (P = 0.002; 95% confidence interval (CI) for difference -1237 to -502 micrograms min ml-1), whereas it was greater in the clonidine group compared with the saline group, although this was not significant (95% CI for difference -423 to 1264 micrograms min ml-1). Arterial pressure was significantly lower in the clonidine group compared with the saline group. Both clonidine and morphine appeared to cause mild sedation. We conclude that clonidine 150 micrograms i.m. does not delay gastric emptying of liquids in a similar manner to morphine.

Jaw thrusting as a clinical test to assess the adequate depth of anaesthesia for insertion of the laryngeal mask

We have studied the efficacy of the loss of response to jaw thrust as a clinical test to assess adequate depth of anaesthesia for insertion of the laryngeal mask in 60 patients. After induction of anaesthesia with propofol (infused using a syringe driver), the patients were randomly allocated to one of two groups. In one group, insertion of the laryngeal mask was attempted immediately after the loss of verbal contact and in the other group, after the loss of motor response to a jaw thrust. Conditions for insertion of the laryngeal mask were assessed. The mean dose of propofol required to obtain loss of verbal contact was 1.94 mg.kg-1 (SD 0.39, 95% confidence intervals (CI) 1.79-2.08 mg.kg-1) and that for the loss of response to jaw thrust was 2.55 mg.kg-1 (SD 0.46, 95% CI 2.38-2.72 mg.kg-1). When depth of anaesthesia was assessed using jaw thrusting, it was always possible to insert the mask and the conditions were optimal in 87% (95% CI 72-95%) of patients. Neither coughing nor gagging occurred. In contrast, conditions were almost always less than optimal when insertion was attempted after the loss of verbal contact. Conditions were significantly better when jaw thrust was used as a clinical test compared with loss of verbal contact (p < < 0.001). No marked haemodynamic depression occurred in any patient. Thus, jaw thrust is a reliable clinical test to assess the adequate depth of anaesthesia for uncomplicated insertion of the laryngeal mask after induction of anaesthesia with propofol.

Simulated difficult intubation. Comparison of the gum elastic bougie and the stylet

A randomised study was carried out to compare the efficacy of the gum elastic bougie and the stylet in a simulated difficult intubation. A laryngoscopic assessment, as described by Cormack and Lehane, was made in 100 patients. A Grade 3 view was then simulated. In the Bougie First Group (50 patients) two attempts were made to pass a gum elastic bougie and a tracheal tube into the trachea. If these first two attempts were not successful, two further attempts at intubation were allowed with a stylet placed in the tracheal tube. In the Stylet First Group (50 patients) the order was reversed. After two attempts the tube was correctly placed in the trachea in 96% of cases in the Bougie First Group compared to only 66% of cases in the Stylet First Group (p < 0.001). We recommend that a gum elastic bougie should be readily available and that anaesthetists should use it in preference to a stylet whenever a good view of the glottis is not immediately available.

The use of a non-invasive method to measure intrapulmonary shunt during one-lung anaesthesia

The Non Invasive Virtual Shunt computer program has previously been described and validated. The system has subsequently been developed to give a real time, continuous trace of virtual shunt. A portable computer connected to routine monitoring equipment displays a plot of virtual shunt updated every 10 s. A practical use of this device in the clinical setting of one-lung anaesthesia is described. The equipment was used to monitor shunt before, during and after surgery in three patients. In one case, a displaced double lumen bronchial tube was detected before there was any other indication of the problem.

Cricoid pressure applied after placement of the laryngeal mask prevents gastric insufflation but inhibits ventilation

We studied 50 patients, in a blind, crossover study, to assess if cricoid pressure applied after placement of the laryngeal mask prevented gastric insufflation without affecting ventilation. After induction of anaesthesia and neuromuscular block, a laryngeal mask was inserted and confirmed to be placed correctly. The lungs were ventilated with a maximum inflation pressure of 15 cm H2O. In the first 25 patients, expiratory volumes were measured with and without cricoid pressure (30 N). On both occasions, a free hand was placed under the patient's neck. In the next 25 patients, the effect of cricoid pressure on ventilation without support of the neck was also studied. The effect of cricoid pressure with support of the neck on gastric insufflation was then assessed using a stethoscope in all 50 patients, while the lungs were ventilated with a maximum inflation pressure of 30 cm H2O. At the end of the study, the position of the mask was re-assessed. Cricoid pressure significantly decreased mean expiratory volume (P << 0.001). This inhibitory effect was significantly greater when the pressure was applied without support of the neck (P << 0.001). Cricoid pressure significantly reduced the incidence of gastric insufflation (12 patients vs one patient; P << 0.001; 95% CI for difference 10.5-33.5%). In no patient was the mask dislodged after these procedures. Thus, although cricoid pressure applied after insertion of the laryngeal mask prevented gastric insufflation, it also decreased ventilation. The inhibitory effect of cricoid pressure on ventilation without support of the neck was greater than cricoid pressure with support of the neck.

The use of bromothymol blue and sodium thiopentone to confirm tracheal intubation

The possibility of using chemical changes to confirm correct tracheal tube placement was investigated with a view to their use in developing countries where more sophisticated methods are unavailable. The effect of bubbling expired gases through a 10% solution of bromothymol blue and a 0.25% solution of thiopentone led to chemical changes producing, in the case of bromothymol blue, a colour change and in that of thiopentone, precipitation, probably due to a change in pH caused by carbon dioxide. We also discovered that the time to precipitation of the thiopentone could be greatly reduced if it was mixed with a precise quantity of lignocaine. These simple end points can reliably confirm the correct placement of a tracheal tube at least as rapidly as the correct use of capnography.

Effects of magnesium sulphate on suxamethonium-induced complications during rapid-sequence induction of anaesthesia

Twenty patients were studied in a double-blind manner to investigate whether magnesium sulphate, when given during a rapid-sequence induction of anaesthesia, lessens the side effects caused by suxamethonium. Patients were randomly allocated to two groups; equal volumes of either magnesium sulphate (40 mg.kg-1) or saline were given during rapid-sequence induction of anaesthesia, after thiopentone but before the administration of suxamethonium (1.5 mg.kg-1). The changes in the serum potassium concentration, the degree of muscle fasciculations and the presence of postoperative myalgia were recorded. The mean serum potassium concentration increased by 0.08 mmol.l-1 in the magnesium group and by 0.1 mmol.l-1 in the control group at 2 min after injection of suxamethonium; in neither group was there a significant increase from baseline values. The systolic blood pressure and heart rate increased in both groups after tracheal intubation. The incidence of fasciculations was significantly lower in the magnesium group. Magnesium did not clinically prolong muscle relaxation. There was no difference between the groups in the incidence of myalgia after surgery (one patient in each group). Since no significant increase in the serum potassium concentration was demonstrated, no assessment could be made of the effect of magnesium sulphate on the serum potassium concentration after administration of suxamethonium.