Cardiopulmonary exercise testing: arm crank vs cycle ergometry

This pilot study compared oxygen consumption during arm crank and cycle ergometer tests in 15 women. The mean (SD) peak oxygen consumption was less with arm cranking (25 (5) ml.kg^?1.min^?1) than with cycling (40 (7) ml.kg^?1.min^?1), p < 0.0001. The mean (SD) anaerobic threshold was less with arm cranking (13 (2) ml.kg^?1.min^?1) than with cycling (20 (4) ml.kg^?1.min^?1), p < 0.0001. There was moderate correlation, r² = 0.60, between the anaerobic thresholds determined by arm and leg exercise, p = 0.0007. This study suggests that arm crank cardiopulmonary exercise testing could be used for pre‐operative assessment in those unable to cycle.     

What is the clinically significant ideal mesenchymal stromal cell count in the management of osteoarthritis of the knee? – Meta-analysis of randomized controlled trials

Study designMeta-analysis.ObjectivesWe aim to identify the clinically significant ideal Mesenchymal Stem Cell (MSC) count in the management of osteoarthritis of knee from Randomized Controlled Trials (RCTs) available in the literature.Materials and methodsWe conducted independent and duplicate electronic database searches including PubMed, Embase, Web of Science, and Cochrane Library till August 2021 for RCTs conducted in the management of knee osteoarthritis using MSC therapy specifying the quantity of MSCs delivered. We categorized the studies based on the MSC count utilized in them into four groups namely <1 × 10⁷ MSCs (Group I), 1-5x10⁷ MSCs (Group II), 5-10 × 10⁷ MSCs (Group III), and >10 × 10⁷ MSCs (Group IV). Visual Analog Score (VAS) for Pain, Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, Knee Osteoarthritis Outcome Score (KOOS), and adverse events were the outcomes analyzed. Analysis was performed in R-platform using OpenMeta [Analyst] software.Results14 studies involving 564 patients were included for analysis. We noted incremental decrease in the VAS with increasing dosage of MSCs at 12 months [Group I,WMD = 2.641(p = 0.854); Group II, WMD = −4.853(p = 0.379); Group III, WMD = −12.154 (p = 0.316); Group IV, WMD = −15.935(p = 0.116)], and 24 months [Group I,WMD = −6(p = 0.001); Group II, WMD = −15(p = 0.001); Group IV, WMD = −20(p = 0.001)]. We also noted incremental improvement in the WOMAC, KOOS with increasing dosage of MSCs at 12 months [Group I, WMD = 7(p = 0.001); Group II, WMD = 28(p = 0.001); Group IV, WMD = 30(p = 0.001)] and [Group II, WMD = −2.562(p = 0.676); Group III, WMD = 7.670(p = 0.099); Group IV, WMD = 13.475(p = 0.261)] respectively. However, we noted significant reduction in the Lysholm score in Group IV, compared to the others at 12 months (WMD = −12.5, 95%CI[-25.883,0.883]) and 24 months (WMD = −6.6, 95%CI[-23.596,10.396]). We did not find any significant increase in the adverse events with incremental dosage of MSCs in any of the groups compared.ConclusionCompared to the four dosage groups of MSCs analyzed, Group III showed consistent significant improvement in pain and functional outcomes analyzed compared to the other groups. Hence, we recommend a cell volume of 5-10 × 10⁷ cells to be delivered to the target site to obtain superior benefits out of the procedure. However, we urge future trials of sufficient quality to validate our findings to arrive at a consensus on the ideal count of MSCs to be delivered in the cellular therapy for knee osteoarthritis.     

Prediction of organ‐specific complications following abdominal aortic aneurysm repair using cardiopulmonary exercise testing

This study aimed at assessing whether measures of aerobic fitness can predict postoperative cardiac and pulmonary complications, 30‐day mortality and length of hospital stay following elective abdominal aortic aneurysm repair. We prospectively collected cardiopulmonary exercise testing data over two years for 130 patients. Upon multivariate analysis, a decreased anaerobic threshold (OR (95% CI) 0.55 (0.37–0.84); p = 0.005) and open repair (OR (95% CI) 6.99 (1.56–31.48); p = 0.011) were associated with cardiac complications. Similarly, an increased ventilatory equivalent for carbon dioxide (OR (95% CI) 1.18 (1.05–1.33); p = 0.005) and open repair (OR (95% CI) 14.29 (3.24–62.90); p < 0.001) were associated with pulmonary complications. Patients who had an endovascular repair had shorter hospital and critical care lengths of stay (p < 0.001). Measures of fitness were not associated with 30‐day mortality or length of hospital stay. Cardiopulmonary exercise testing variables, therefore, seem to predict different postoperative complications following abdominal aortic aneurysm repair, which adds value to their routine use in risk stratification and optimisation of peri‐operative care.     

A randomised controlled trial of the analgesia nociception index for intra-operative remifentanil dose and pain after gynaecological laparotomy

We aimed to investigate the effect of the analgesia nociception index on postoperative pain. We randomly allocated 170 women scheduled for gynaecological laparotomy and analysed results from 159: in 80 women, remifentanil was infused to maintain analgesia nociception indices 50–70; and in 79 women, remifentanil was infused to maintain systolic blood pressure < 120% of baseline values. The primary outcome was the proportion of women with pain scores ≥ 5 (scale 0–10) within 40 min of admission to recovery. The proportion of women with pain scores ≥ 5 was 62/80 (78%) vs. 64/79 (81%), p = 0.73. Mean (SD) doses of fentanyl in recovery were 53.6 (26.9) μg vs. 54.8 (20.8) μg, p = 0.74. Intra-operative remifentanil doses were 0.124 (0.050) μg.kg⁻¹.min⁻¹ vs. 0.129 (0.044) μg.kg⁻¹.min⁻¹, p = 0.55.     

Validity and Reproducibility of an Incremental Sit-To-Stand Exercise Test for Evaluating Anaerobic Threshold in Young,Healthy Individuals

Sit-to-stand exercise (STS) is a common activity of daily living. The objectives of the present study were: 1) to assess the validity of aerobic fitness measurements based on anaerobic thresholds (ATs), during incremental sit-to-stand exercise (ISTS) with and without arm support compared with an incremental cycle-ergometer (CE) test; and 2) to examine the reproducibility of the AT measured during the ISTSs. Twenty-six healthy individuals randomly performed the ISTS and CE test. Oxygen uptakes at the AT (AT-VO₂) and heart rate at the AT (AT-HR) were determined during the ISTSs and CE test, and repeated-measures analyses of variance and Tukey’s post-hoc test were used to evaluate the differences between these variables. Pearson correlation coefficients were used to assess the strength of the relationship between AT-VO₂ and AT-HR during the ISTSs and CE test. Data analysis yielded the following correlations: AT-VO₂ during the ISTS with arm support and the CE test, r = 0.77 (p < 0.05); AT-VO₂ during the ISTS without arm support and the CE test, r = 0.70 (p < 0.05); AT-HR during the ISTS with arm support and the CE test, r = 0.80 (p < 0.05); and AT-HR during the ISTS without arm support and the CE test, r = 0.66 (p < 0.05). The AT-VO₂ values during the ISTS with arm support (18.5 ± 1.9 mL·min^-1·kg^-1) and the CE test (18.4 ± 1.8 mL·min^-1·kg^-1) were significantly higher than those during the ISTS without arm support (16.6 ± 1.8 mL·min^-1·kg^-1; p < 0.05). The AT-HR values during the ISTS with arm support (126 ± 10 bpm) and the CE test (126 ± 13 bpm) were significantly higher than those during the ISTS without arm support (119 ± 9 bpm; p < 0.05). The ISTS with arm support may provide a cardiopulmonary function load equivalent to the CE test; therefore, it is a potentially valid test for evaluating AT-VO2 and AT-HR in healthy, young adults.

Key points

• The ISTS is a simple test that varies only according to the frequency of standing up, and requires only a small space and a chair.
• The ISTS with arm support is valid and reproducible, and is a safe test for evaluating AT in healthy young adults.
• For evaluating the AT, the ISTS may serve as a valid alternative to conventional CPX, using either a cycle ergometer or treadmill, in cases where the latter methods are difficult to implement.

Key words: Sit-to-stand, cycle ergometer, anaerobic threshold, correlations, reproducibility, validity     

Postoperative microcirculatory perfusion and endothelial glycocalyx shedding following cardiac surgery with cardiopulmonary bypass

We investigated microcirculatory perfusion disturbances following cardiopulmonary bypass in the early postoperative period and whether the course of these disturbances mirrored restoration of endothelial glycocalyx integrity. We performed sublingual sidestream dark field imaging of the microcirculation during the first three postoperative days in patients who had undergone on-pump coronary artery bypass graft surgery. We calculated the perfused vessel density, proportion of perfused vessels and perfused boundary region. Plasma was obtained to measure heparan sulphate and syndecan-1 levels as glycocalyx shedding markers. We recruited 17 patients; the mean (SD) duration of non-pulsatile cardiopulmonary bypass was 103 (18) min, following which 491 (29) ml autologous blood was transfused through cell salvage. Cardiopulmonary bypass immediately decreased both microcirculatory perfused vessel density; 11 (3) vs. 16 (4) mm.mm⁻², p = 0.052 and the proportion of perfused vessels; 92 (5) vs. 69 (9) %, p < 0.0001. The proportion of perfused vessels did not increase after transfusion of autologous salvaged blood following cardiopulmonary bypass; 72 (7) %, p = 0.19 or during the first three postoperative days; 71 (5) %, p < 0.0001. The perfused boundary region increased after cardiopulmonary bypass; 2.2 (0.3) vs. 1.9 (0.3) μm, p = 0.037 and during the first three postoperative days; 2.4 (0.3) vs. 1.9 (0.3) μm, p = 0.003. Increased plasma heparan sulphate levels were inversely associated with the proportion of perfused vessels during cardiopulmonary bypass; R = −0.49, p = 0.02. Plasma syndecan-1 levels were inversely associated with the proportion of perfused vessels during the entire study period; R = −0.51, p < 0.0001. Our study shows that cardiopulmonary bypass-induced acute microcirculatory perfusion disturbances persist in the first three postoperative days, and are associated with prolonged endothelial glycocalyx shedding. This suggests prolonged impairment and delayed recovery of both microcirculatory perfusion and function after on-pump cardiac surgery.     

Comparison of portable blood-warming devices under simulated pre-hospital conditions: a randomised in-vitro blood circuit study

Pre-hospital transfusion of blood products is a vital component of many advanced pre-hospital systems. Portable fluid warmers may be utilised to help prevent hypothermia, but the limits defined by manufacturers often do not reflect their clinical use. The primary aim of this randomised in-vitro study was to assess the warming performance of four portable blood warming devices (Thermal Angel, Hypotherm X LG, °M Warmer, Buddy Lite) against control at different clinically-relevant flow rates. The secondary aim was to assess haemolysis rates between devices at different flow rates. We assessed each of the four devices and the control, at flow rates of 50 ml.min⁻¹, 100 ml.min⁻¹ and 200 ml.min⁻¹, using a controlled perfusion circuit with multisite temperature monitoring. Free haemoglobin concentration, a marker of haemolysis, was measured at multiple points during each initial study run with spectrophotometry. At all flow rates, the four devices provided superior warming performance compared with the control (p < 0.001). Only the °M Warmer provided a substantial change in temperature at all flow rates (mean (95%CI) temperature change of 21.1 (19.8–22.4) °C, 20.4 (19.1–21.8) °C and 19.4 (17.7–21.1) °C at 50 ml.min⁻¹, 100 ml.min⁻¹ and 200 ml.min⁻¹, respectively). There was no association between warming and haemolysis with any device (p = 0.949) or flow rate (p = 0.169). Practical issues, which may be relevant to clinical use, also emerged during testing. Our results suggest that there were significant differences in the performance of portable blood warming devices used at flow rates encountered in clinical practice.     

Maximal Fat Oxidation: Comparison between Treadmill,Elliptical and Rowing Exercises

Fat oxidation during exercise is associated with cardio-metabolic benefits, but the extent of which whole-body exercise modality elicits the greatest fat oxidation remains unclear. We investigated the effects of treadmill, elliptical and rowing exercise on fat oxidation in healthy individuals. Nine healthy males participated in three, peak oxygen consumption tests, on a treadmill, elliptical and rowing ergometer. Indirect calorimetry was used to assess maximal oxygen consumption (V̇O_2peak), maximal fat oxidation (MFO) rates, and the exercise intensity MFO occurred (Fat_max). Mixed venous blood was collected to assess lactate and blood gases concentrations. While V̇O_2peak was similar between exercise modalities, MFO rates were higher on the treadmill (mean ± SD; 0.61 ± 0.06 g·min^-1) compared to both the elliptical (0.41 ± 0.08 g·min^-1, p = 0.022) and the rower (0.40 ± 0.08 g·min^-1, p = 0.017). Fat_max values were also significantly higher on the treadmill (56.0 ± 6.2 %V̇O_2peak) compared to both the elliptical (36.8 ± 5.4 %V̇O_2peak, p = 0.049) and rower (31.6 ± 5.0 %V̇O_2peak, p = 0.021). Post-exercise blood lactate concentrations were also significantly lower following treadmill exercise (p = 0.021). Exercising on a treadmill maximizes fat oxidation to a greater extent than elliptical and rowing exercises, and remains an important exercise modality to improve fat oxidation, and consequently, cardio-metabolic health.Key points

• The ability to oxidize fat has been associated with improved oxidative enzymes activity and mitochondrial biogenesis.
• The present study examined the effects of treadmill, elliptical, and rower exercises on maximal fat oxidation rates (MFO), the intensity were MFO was observed (Fat_max) and on fat oxidation curves in healthy and young participants.
• Both MFO and Fat_max were higher during treadmill exercise. Multiple linear mixed-effects regression analyses further revealed an effect of exercise modality on fat oxidation curves.
• Adequate selection of exercise modality during training may have a meaningful impact on substrate oxidation. Treadmill exercise should be considered in training design for those looking to maintain or improve metabolic profiling.

Key words: Substrate oxidation, indirect calorimetry, exercise modality, metabolism     

The association of pre‐operative home accelerometry with cardiopulmonary exercise variables

We investigated the association of pre‐operative activity, reported by the Duke Activity Score Index, Short Form‐12 and measured by an accelerometer worn at home, with five cardiopulmonary exercise variables: peak power; peak oxygen consumption; anaerobic threshold; and ventilatory equivalents for oxygen and carbon dioxide. Fifty patients scheduled for major surgery underwent a standard pre‐operative cardiopulmonary exercise test and wore a chest‐mounted triaxial accelerometer for a mean (SD) duration of 3.2 (0.4) days. The Duke Activity Score Index and six accelerometer variables were significantly correlated with all five cardiopulmonary exercise variables, Pearson correlation coefficients 0.5–0.7, p = 0.02 to p < 0.001. Our results can guide future studies that measure physical activity for pre‐operative assessment and interventions.     

A physiological study to determine the mechanism of carbon dioxide clearance during apnoea when using transnasal humidified rapid insufflation ventilatory exchange (THRIVE)

Clinical observations suggest that compared with standard apnoeic oxygenation, transnasal humidified rapid-insufflation ventilatory exchange using high-flow nasal oxygenation reduces the rate of carbon dioxide accumulation in patients who are anaesthetised and apnoeic. This suggests that active gas exchange takes place, but the mechanisms by which it may occur have not been described. We used three laboratory airway models to investigate mechanisms of carbon dioxide clearance in apnoeic patients. We determined flow patterns using particle image velocimetry in a two-dimensional model using particle-seeded fluorescent solution; visualised gas clearance in a three-dimensional printed trachea model in air; and measured intra-tracheal turbulence levels and carbon dioxide clearance rates using a three-dimensional printed model in air mounted on a lung simulator. Cardiogenic oscillations were simulated in all experiments. The visualisation experiments indicated that gaseous mixing was occurring in the trachea. With no cardiogenic oscillations applied, mean (SD) carbon dioxide clearance increased from 0.29 (0.04) ml.min⁻¹ to 1.34 (0.14) ml.min⁻¹ as the transnasal humidified rapid-insufflation ventilatory exchange flow rate was increased from 20 l.min⁻¹ to 70 l.min⁻¹ (p = 0.0001). With a cardiogenic oscillation of 20 ml.beat⁻¹ applied, carbon dioxide clearance increased from 11.9 (0.50) ml.min⁻¹ to 17.4 (1.2) ml.min⁻¹ as the transnasal humidified rapid-insufflation ventilatory exchange flow rate was increased from 20 l.min⁻¹ to 70 l.min⁻¹ (p = 0.0014). These findings suggest that enhanced carbon dioxide clearance observed under apnoeic conditions with transnasal humidified rapid-insufflation ventilatory exchange, as compared with classical apnoeic oxygenation, may be explained by an interaction between entrained and highly turbulent supraglottic flow vortices created by high-flow nasal oxygen and cardiogenic oscillations.     

Associations of nadir haemoglobin level and red blood cell transfusion with mortality and length of stay in surgical specialties: a retrospective cohort study

Few studies have investigated if, and how, red cell transfusion and anaemia interact. We analysed 60,955 admissions to three metropolitan hospitals in Western Australia between 2008 and 2017 to determine whether the relationship between red cell transfusion and outcomes in surgical patients differed by lowest (nadir) level of haemoglobin. At levels above 100 g.l⁻¹, in-hospital, 30-day and 1-year mortality were higher with transfusion, the adjusted odds ratios (ORs) (95%CI) being 8.80 (4.43–17.45) p < 0.001 and 3.68 (1.93–7.02) p < 0.001 and the adjusted hazard ratio (95%CI) being 1.83 (1.28–2.61) p = 0.001, respectively. Likewise, between 90 g.l⁻¹ and 99 g.l⁻¹, in-hospital, 30-day and 1-year mortality were higher with transfusion, the adjusted odds ratio (95%CI) being 3.76 (2.23–6.34) p < 0.001 and 1.96 (1.23–3.12) p < 0.001 and the adjusted hazard ratio (95%CI) being 1.34 (1.05–1.70) p = 0.017, respectively. Length of stay was longer with transfusion at nadir haemoglobin levels above 100 g.l⁻¹ and in the following ranges: 90–99 g.l⁻¹, 80–89 g.l⁻¹, 70–79 g.l⁻¹ and 60–69 g.l⁻¹, the adjusted rate ratio (95%CI) being 1.38 (1.25–1.53) p < 0.001, 1.18 (1.10–1.27) p < 0.001, 1.17 (1.13–1.22) p < 0.001, 1.07 (1.02–1.12) p = 0.003 and 1.24 (1.13–1.36) p < 0.001, respectively. Mortality was higher with red cell transfusion at haemoglobin levels greater than 90 g.l⁻¹, whereas at all levels below 90 g.l⁻¹ mortality was not significantly higher or lower. Length of stay was longer with transfusion at nadir haemoglobin levels of 60 g.l⁻¹ or above. Our results suggest that nadir haemoglobin modified the relationship between red cell transfusion and outcomes and adds to the evidence recommending caution before transfusing red cells.     

Remifentanil for labour analgesia: a double‐blinded,randomised controlled trial of maternal and neonatal effects of patient‐controlled analgesia versus continuous infusion

This trial aimed to compare the maternal and neonatal effects of remifentanil given by patient‐controlled analgesia (PCA) or continuous infusion for labour analgesia. Patient controlled analgesia was administered using increasing stepwise boluses from 0.1 to 0.4 μg.kg^?1 (0.1 μg.kg^?1 increment, 2 min lockout, n = 30). Continuous infusion used rates from 0.05 to 0.2 μg.kg^?1.min^?1 (0.05 μg.kg^?1.min^?1 increment, n = 30). Dose increments were given on request. Women reported lowest pain scores (median (IQR [range]) of 3 (2–4 [2–5]) for PCA and 4 (3–5.25 [3–7]) for continuous infusion (p = 0.004) at 60 min after the beginning of analgesia. The mean (SD) remifentanil umbilical vein/maternal artery ratio in the PCA and infusion groups were 0.74 (0.45) vs 0.70 (0.52), respectively (p = 0.776). The mean (SD) umbilical artery/umbilical vein ratios were 0.31 (0.12) vs 0.26 (0.07), respectively (p = 0.088). Maternal and neonatal adverse reactions of remifentanil were similar between the two groups. The total remifentanil consumption (median (IQR [range]) during PCA administration was lower than continuous infusion, 1.34 (1.22–1.48 [0.89–1.69]) mg vs 1.49 (1.35–1.61 [1.12–1.70] mg; p = 0.011). The results suggest that remifentanil PCA provides better pain relief and similar placental transfer compared with continuous infusion.     

A randomised controlled trial of dexmedetomidine for delirium in adults undergoing heart valve surgery

Dexmedetomidine might reduce delirium after cardiac surgery. We allocated 326 participants to an infusion of dexmedetomidine at a rate of 0.6 μg kg⁻¹ for 10 min and then at 0.4 μg.kg⁻¹.h⁻¹ until the end of surgery; 326 control participants received comparable volumes of saline. We detected delirium in 98/652 (15%) participants during the first seven postoperative days: 47/326 after dexmedetomidine vs. 51/326 after placebo, p = 0.62, adjusted relative risk (95%CI) 0.86 (0.56–1.33), p = 0.51. Postoperative renal impairment (Kidney Disease Improving Global Outcomes stages 1, 2 and 3) was detected in 46, 9 and 2 participants after dexmedetomidine and 25, 7 and 4 control participants, p = 0.040. Intra-operative dexmedetomidine infusion did not reduce the incidence of delirium after cardiac valve surgery but might impair renal function.     

Effect of intra-operative intravenous lidocaine on opioid consumption after bariatric surgery: a prospective,randomised, blinded,placebo-controlled study

Peri-operative lidocaine infusion warrants investigation in bariatric surgery because obese patients present different physiological and pharmacological risks. This single-centre, prospective, randomised double-blind placebo-controlled study enrolled obese patients scheduled for laparoscopic bariatric surgery using an enhanced recovery protocol. Patients received either lidocaine (bolus of 1.5 mg.kg⁻¹, then a continuous infusion of 2 mg.kg⁻¹.h⁻¹ until the end of the surgery, then 1 mg.kg⁻¹.h⁻¹ for 1 h in the recovery area) or identical volumes and rates of 0.9% saline. The primary outcome was the consumption of the equivalent of oxycodone consumption over the first 3 postoperative days. Secondary outcomes were: postoperative pain; incidence of nausea and vomiting; bowel function recovery; and lengths of stay in the recovery area and in hospital. Plasma concentrations of lidocaine were measured. On the 178 patients recruited, data were analysed from 176. The median (IQR [range]) equivalent intravenous oxycodone consumption was 3.3 mg (0.0–6.0 [0.0–14.5]) and 5.0 mg (3.3–7.0 [3.3–20.0]) in the lidocaine and saline groups, respectively (difference between medians (95%CI): 1.7 (0.6–3.4) mg; p = 0.004). Length of stay in the recovery area, postoperative pain, nausea and vomiting, day of recovery of bowel function, and length of stay in hospital were not different between groups. Mean (SD) lidocaine plasma concentrations were 2.44 (0.70) µg.ml⁻¹ and 1.77 (0.51) µg.ml⁻¹ at the end of surgery and 1 hour after the end of infusion, respectively. Lidocaine infusion during bariatric surgery resulted in a clinically non-relevant difference in postoperative oxycodone consumption.     

Adaptation to reduced lung function in children and young people with spinal deformity

BackgroundSevere scoliosis can affect respiratory function in growing patients and produce cardiopulmonary complications, leading to significant morbidity. The development of spinal deformity may impact on young patients’ level of function and reported quality of life (QOL). The aim of this study was to investigate the relationship between lung function, exercise capacity and quality of life in young patients with spinal deformity.MethodsThis is a retrospective analysis of 104 patients (31% male, 69% female with mean age 14.9yrs). 77% of patients had an adolescent idiopathic scoliosis, with the remainder having other scoliosis diagnoses or Scheuermann’s kyphosis. Principal outcomes included Spirometry [FEV₁, FVC], Whole Body Plethysmography, Cardiopulmonary Exercise Testing [CPET] and patient outcome questionnaires (with SRS-22). CPET measures included maximal exercise capacity [VO_2peak] as well as VO₂ at ventilatory threshold [VT] expressed as %predicted VO_2max-a measure of physical conditioning, and minute ventilation [V_E] from which breathing reserve [BR] could be calculated.ResultsMean (±SD) main thoracic scoliosis was 59.9⁰ (±15.2⁰), and mean kyphosis in those with Scheuermann’s condition was 95.3⁰ (±11.5⁰). No correlation was elicited between FEV₁ or FVC (%predicted) and VO_2peak (%predicted) in this patient cohort. Greater thoracic curves were associated with lower FEV₁ (%predicted), r = −0.343, p = 0.001, FVC (%predicted), r = −0.307, p = 0.003 and BR (%) at the end of exercise (r = −0.-0.459, p < 0.001). The patient cohort had a mean (sd) VO₂peak of 98(17) %predicted, with greater VO₂peak levels recorded in female subjects, those of younger age and those with higher scoliosis angles. Those with better lung function [FEV₁ (%predicted)] had better BR (%) at the end of exercise (r = 0.483, p < 0.001). SRS-22 scores correlated significantly with VO_2peak (%predicted) (total SRS-22 versus VO_2peak (%predicted), r = 0.336, p = 0.002).ConclusionLarger thoracic scoliotic curves are associated with poorer lung function but better exercise capacity, likely related to higher levels of physical conditioning. Higher QOL scores were recorded in patients who had greater VO_2peak levels, suggesting that exercise capacity may be a protective factor for emotional well-being in patients with spinal deformity.     

The effect of a low-dose naloxone infusion on the incidence of respiratory depression after intrathecal morphine administration for major open hepatobiliary surgery: a randomised controlled trial

Intrathecal morphine is an analgesic option for major hepatopancreaticobiliary procedures but is associated with a risk of respiratory depression. We hypothesised that a postoperative low-dose naloxone infusion would reduce the incidence of respiratory depression without an increase in pain scores. Patients scheduled for major open hepatopancreaticobiliary surgery and who were receiving 10 μg.kg⁻¹ intrathecal morphine were eligible for inclusion. Patients were allocated randomly to receive a postoperative infusion of naloxone 5 μg.kg⁻¹.h⁻¹ (naloxone group) or saline at an identical infusion rate (control group) until the morning after surgery. Clinicians, nursing staff and patients were blinded to group allocation. The primary outcome measure was the incidence of respiratory depression (respiratory rate < 10 breaths.min⁻¹ and/or oxygen saturation < 90%). Secondary outcome measures included: arterial partial pressure of carbon dioxide; pain score; requirement for supplemental analgesic; and incidence of nausea and vomiting, pruritus and sedation. In total, data from 95 patients (48 in the naloxone group and 47 in the control group) were analysed. The incidence of respiratory depression was lower in the naloxone group compared with the control group (10/48 vs. 21/47 patients, respectively; p = 0.037, relative risk 0.47 (95%CI 0.25–0.87). Maximum pain scores were greater for patients allocated to the naloxone group compared with control (median 5 (95%CI 4–6) vs. 4 (95%CI 2–4), respectively; p < 0.001). A low-dose naloxone infusion decreases the incidence of respiratory depression following intrathecal morphine administration in patients having major hepatopancreaticobiliary surgery at the expense of a small increase in postoperative pain.     

A randomised controlled trial of intravenous dexmedetomidine added to dexamethasone for arthroscopic rotator cuff repair and duration of interscalene block

Prolongation of peripheral nerve blockade by intravenous dexamethasone may be extended by intravenous dexmedetomidine. We randomly allocated 122 participants who had intravenous dexamethasone 0.15 mg.kg⁻¹ before interscalene brachial plexus block for day-case arthroscopic rotator cuff repair to intravenous saline (62 participants) or intravenous dexmedetomidine 1 μg.kg⁻¹ (60 participants). The primary outcome was time from block to first oral morphine intake during the first 48 postoperative hours. Fifty-nine participants reported taking oral morphine, 25/62 after placebo and 34/60 after dexmedetomidine, p = 0.10. The time to morphine intake was shorter after dexmedetomidine, hazard ratio (95%CI) 1.68 (1.00–2.82), p = 0.049. Median (IQR [range]) morphine doses were 0 (0–12.5 [0–50]) mg after control vs. 10 (0–30 [0–50]) after dexmedetomidine, a difference (95%CI) of 7 (0–10) mg, p = 0.056. There was no effect of dexmedetomidine on pain at rest or on movement. Intra-operative hypotension was recorded for 27/62 and 50/60 participants after placebo vs. dexmedetomidine, respectively, p < 0.001. Other outcomes were similar, including durations of sensory and motor block. In conclusion, dexmedetomidine shortened the time to oral morphine consumption after interscalene block combined with dexamethasone and caused intra-operative hypotension.     

Evaluating the ventilatory effect of transnasal humidified rapid insufflation ventilatory exchange in apnoeic small children with two different oxygen flow rates: a randomised controlled trial*

Transnasal humidified rapid insufflation ventilatory exchange prolongs safe apnoeic oxygenation time in children. In adults, transnasal humidified rapid insufflation ventilatory exchange is reported to have a ventilatory effect with PaCO₂ levels increasing less rapidly than without it. This ventilatory effect has yet to be reproduced in children. In this non-inferiority study, we tested the hypothesis that children weighing 10–15 kg exhibit no difference in carbon dioxide clearance when comparing two different high-flow nasal therapy flow rates during a 10-min apnoea period. Following standardised induction of anaesthesia including neuromuscular blockade, patients were randomly allocated to high-flow nasal therapy of 100% oxygen at 2 or 4 l.kg⁻¹.min⁻¹. Airway patency was ensured by continuous jaw thrust. The study intervention was terminated for safety reasons when SpO₂ values dropped < 95%, or transcutaneous carbon dioxide levels rose > 9.3 kPa, or near-infrared spectroscopy values dropped > 20% from their baseline values, or after an apnoeic period of 10 min. Fifteen patients were included in each group. In the 2 l.kg⁻¹.min⁻¹ group, mean (SD) transcutaneous carbon dioxide increase was 0.46 (0.11) kPa.min⁻¹, while in the 4 l.kg⁻¹.min⁻¹ group it was 0.46 (0.12) kPa.min⁻¹. The upper limit of a one-sided 95%CI for the difference between groups was 0.07 kPa.min⁻¹, lower than the predefined non-inferiority margin of 0.147 kPa.min⁻¹ (p = 0.001). The lower flow rate of 2 l.kg⁻¹.min⁻¹ was non-inferior to 4 l.kg⁻¹.min⁻¹ relative to the transcutaneous carbon dioxide increase. In conclusion, an additional ventilatory effect of either 2 or 4 l.kg⁻¹.min⁻¹ high-flow nasal therapy in apnoeic children weighing 10–15 kg appears to be absent.     

Variables associated with survival in patients with invasive bladder cancer with and without surgery

We recorded the survival of 141 patients assessed for radical cystectomy, which included cardiopulmonary exercise testing. The median Kaplan-Meier survival estimates were: 1540 days for the whole cohort; 2200 days after cystectomy scheduled (n = 108); and 843 days without surgery. The mortality hazard remained double that expected for a matched general population, but survival was better in patients scheduled for surgery than those who were not: the mortality hazard ratio (95%CI) after cystectomy was 0.43 (0.26–0.73) the mortality hazard without surgery, p = 0.001. The mortality hazard ratios for the three-variable Bayesian Model Averaging survival model for all 141 patients were: referral for surgery (0.5); haemoglobin concentration (0.98); and efficiency of carbon dioxide output (1.05). Efficiency of carbon dioxide output was the single variable in the postoperative model (n = 108), mortality hazard 1.08 (per unit increase). The ratio of observed to expected peak oxygen consumption associated best with mortality in 33 patients not referred for surgery, hazard ratio 0.001. Our results can inform consultations with patients with invasive bladder cancer and suggest that interventions to increase fitness and haemoglobin may improve survival in patients who do and who do not undergo radical cystectomy.     

A randomised study of intranasal dexmedetomidine and oral ketamine for premedication in children

We studied the effects of intranasal dexmedetomidine combined with oral ketamine for premedication in children. One hundred and sixty children aged between 2 and 6 years were randomly allocated to one of four groups: 1 μg.kg^?1 intranasal dexmedetomidine with 3 mg.kg^?1 oral ketamine (Group 1); 1 μg.kg^?1 intranasal dexmedetomidine with 5 mg.kg^?1 oral ketamine (Group 2); 2 μg.kg^?1 intranasal dexmedetomidine with 3 mg.kg^?1 oral ketamine (Group 3); and 2 μg.kg^?1 intranasal dexmedetomidine with 5 mg.kg^?1 oral ketamine (Group 4). Sedation levels 10, 20 and 30 min after premedication were evaluated using a 5‐point sedation scale. A 4‐point emotional state score was used to evaluate patients when they were separated from their parents and their response to intravenous cannulation or facemask application. Approximately 90% of patients readily accepted premedication and onset times of acceptable sedation were similar in all four groups. Patients in Group 4 were significantly more sedated than those in Group 1 after 30 min (p = 0.036). A significantly higher proportion of patients in Group 3 (84%) and Group 4 (87%) accepted intravenous cannulation compared with those in Group 1 (40%) and Group 2 (54%) (p = 0.001). We conclude that the administration of 2 μg.kg^?1 intranasal dexmedetomidine and 3 mg.kg^?1 oral ketamine was the optimal combination, with children being easily separated from their parent, accepting intravenous cannulation and without causing excessive side‐effects or postoperative complications.