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.     

Postoperative morphine concentration in infants with or without biliary atresia and its association with hepatic blood flow

We measured pre‐operative hepatic blood flow and postoperative morphine concentration in infants with or without biliary atresia. Thirty‐four infants (0–3 months) with biliary atresia undergoing portoenterostomy (Kasai operation) were included and hepatic blood flow was assessed by magnetic resonance imaging before surgery in 12 of them. Sixteen subjects (0–3 months) without liver disease undergoing abdominal or pelvic surgery acted as controls and six of them had hepatic blood flow assessed. Intravenous morphine (8 μg.kg^?1.h^?1) was administered to all patients postoperatively. The median (IQR [range]) relative hepatic blood flow was 3.51 (2.72–3.88 [1.68–4.43]) with and 3.15 (2.66–4.42 [2.30–5.01]) without biliary atresia (p = 0.851). The median (IQR [range]) morphine concentration after 24 h infusion was 5.9 (4.5–16.4 [2.9–42.2]) ng.ml^?1 and 6.4 (3.2–12.0 [1.9–48.6]) ng.ml^?1, respectively (p = 0.460). An inverse regression relation was found between the morphine concentration and the hepatic perfusion index (R² = 0.519, p = 0.001). Compensatory increases in hepatic arterial blood flow maintain the total hepatic blood flow in infants with biliary atresia.     

Onset of labour epidural analgesia with low‐dose bupivacaine and different doses of fentanyl

This study investigated the effects of different doses of epidural fentanyl on the time to onset of epidural analgesia in women in early labour. We hypothesised that onset of epidural labour analgesia (the primary outcome defined as time in minutes from completion of epidural bolus to the first uterine contraction with a numeric pain rating scale [NPRS] score ≤ 3) would be faster with 100 μg of fentanyl epidural bolus compared with 20 μg or 50 μg. Epidural labour analgesia was initiated with 20 μg of fentanyl (F20 group), 50 μg (F50 group) or 100 μg (F100 group) along with 10 ml bupivacaine 0.08% as the loading dose. We randomly allocated 105 patients, with 35 patients in each group. Median (IQR [range]) time to achieve NPRS ≤ 3 was 18 (11–30 [6–20]) min in F20, 10 (8–19 [4–30]) min in F50 and 10 (6–16 [3–30]) min in F100 groups. There was a significant difference in onset times comparing F100 with F20 (p < 0.001) and F50 with F20 (p = 0.007), but not significantly different comparing F100 with F50 (p = 0.19). The median (IQR [range]) time from the epidural loading dose to first patient controlled epidural analgesia bolus was 61 min (20–165 [20–420]) in F20, 118 min (66–176 [20–396]) in F50 and 150 min (66–214 [30‐764]) in F100 groups. This was not statistically significant (p = 0.16) comparing the F20 with the F100 group. There were no significant differences in maternal side‐effects, mode of delivery, patient satisfaction scores or neonatal Apgar scores between all groups. We conclude that the 50 μg and 100 μg fentanyl doses were associated with reduced onset times to effective analgesia compared with the 20 μg dose.     

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.     

A randomised controlled trial of the non-inferiority of erector spinae plane block vs. thoracic paravertebral block for laparoscopic nephro-ureterectomy

Erector spinae plane block and paravertebral block can provide analgesia for abdominal surgery. It is unclear whether erector spinae block is inferior to paravertebral block. We aimed to determine whether sufentanil dose and pain intensity (11-point scale) to 24 h after erector spinae block exceeded those after paravertebral block by no more than 5 μg and 1 point, respectively. We randomly allocated 166 adults to 0.4 ml.kg⁻¹ ropivacaine 0.375% before scheduled laparoscopic nephroureterectomy, 83 each to erector spinae or paravertebral injection. We measured incision pain and intra-abdominal pain at rest and on movement 0.5 h, 2 h, 6 h, 18 h, 24 h and 48 h after surgery. Median (IQR [range]) cumulative sufentanil dose after erector spinae block was 15 (5–30 [0–105]) μg vs. 20 (10–50 [0–145]) μg after paravertebral block, median (95%CI) difference 5 μg (0–10), erector spinae non-inferiority p < 0.001. Median (IQR [range]) pain were 1.5 (1.0–2.0 [0.0–5.3]) after erector spinae block vs. 2.0 (1.0–2.5 [0.0–6.0]) after paravertebral block, median (95% CI) difference 0.3 (0.0–0.5), erector spinae non-inferiority p < 0.001. Adverse events did not differ between groups. Erector spinae block analgesia was not inferior to paravertebral block analgesia after laparoscopic nephroureterectomy.     

Effect of magnesium sulphate on sugammadex reversal time for neuromuscular blockade: a randomised controlled study

Magnesium potentiates neuromuscular blockade. Sugammadex reverses rocuronium‐induced blockade. The aim of this study was to determine the effect of pre‐treatment with magnesium sulphate on sugammadex reversal time for neuromuscular blockade. Seventy‐three patients were randomly assigned to receive magnesium sulphate (40 mg.kg^?1) or saline intravenously. After anaesthetic induction, continuous train‐of‐four monitoring was performed and rocuronium was administered (0.6 mg.kg^?1). When a second twitch appeared, the patients received sugammadex (2 mg.kg^?1). The median (IQR [range]) reversal time of moderate neuromuscular blockade to a train‐of‐four ratio of 0.9 facilitated by sugammadex was 115 (93?177.5 [68?315]) s in the magnesium group and 120 (105?140 [70?298]) s in the saline group (p = 0.79). The median (IQR [range]) clinical duration was 45 (35.5?53 [22?102]) min in the magnesium group and 37 (31?43 [19?73]) min in the saline group (p = 0.031). Pre‐treatment with magnesium did not significantly affect sugammadex reversal time of moderate neuromuscular blockade induced by rocuronium.     

Forces generated by Macintosh and GlideScope® laryngoscopes in four airway‐training manikins

We measured forces generated by Macintosh and GlideScope^® laryngoscope blades during airway intubation by 16 participants in four manikins: Laerdal^® SimMan; TruCorp AirSim? Advance; Laerdal^® Airway Management Trainer; and Ambu^® Airway Man. Both laryngoscopes generated the least force in the Laerdal Airway Management Trainer and the most in the Ambu Airway Man. The respective median (IQR [range]) forces generated by the Macintosh blade were 2 (1–4 [1–7]) N vs 9 (7–13 [5–16]) N, p = 0.00004, with peak forces 9 (5–11 [3–16]) N vs 18 (12–22 [3–31]) N, p = 0.0004. The respective average and peak forces generated by the GlideScope blade were 1 (1–2 [0–3]) N vs 4 (3–5 [2–6]) N, p = 0.00001, and 4 (2–7 [0–12]) N vs 7 (4–9 [3–18]) N, p = 0.054.     

Induction of general anaesthesia by effect‐site target‐controlled infusion of propofol: influence of pharmacokinetic model and ke0 value

We studied the use of a new k_e0 value (0.6 min^?1) for the Marsh pharmacokinetic model for propofol. Speed of induction and side‐effects produced were compared with three other target‐controlled infusion systems. Eighty patients of ASA physical status 1–2 were studied in four groups in a prospective, randomised study. Median (IQR [range]) induction times were shorter with the Marsh model in effect‐site control mode with a k_e0 of either 0.6 min^?1 (81 (61–101 [49–302])s, p < 0.01), or 1.2 min^?1 (78 (68–208 [51–325])s, p < 0.05), than with the Marsh model in blood concentration control (132 (90–246 [57–435])). The Schnider model in effect‐site control produced induction times that were longer (298 (282–398 [58–513])s) than those observed with the Marsh model in blood control (p < 0.05), or either effect‐site control mode (p < 0.001). There were no differences in the magnitude of blood pressure changes or frequency of apnoea between groups.     

The effect of intrathecal bupivacaine/morphine on quality of recovery in robot-assisted radical prostatectomy: a randomised controlled trial

Robot-assisted radical prostatectomy causes discomfort in the immediate postoperative period. This randomised controlled trial investigated if intrathecal bupivacaine/morphine, in addition to general anaesthesia, could be beneficial for the postoperative quality of recovery. One hundred and fifty-five patients were randomly allocated to an intervention group that received intrathecal 12.5 mg bupivacaine/300 μg morphine (20% dose reduction in patients > 75 years) or a control group receiving a subcutaneous sham injection and an intravenous loading dose of 0.1 mg.kg⁻¹ morphine. Both groups received standardised general anaesthesia and the same postoperative analgesic regimen. The primary outcome was a decrease in the Quality of Recovery-15 (QoR-15) questionnaire score on postoperative day 1. The intervention group (n = 76) had less reduction in QoR-15 on postoperative day 1; median (IQR [range]) 10% (1–8 [−60% to 50%]) vs. 13% (5–24 [−6% to 50%]), p = 0.019, and used less morphine during the admission; 2 mg (1–7 [0–41 mg]) vs. 15 mg (12–20 [8–61 mg]), p < 0.001. Furthermore, they perceived lower pain scores during exertion; numeric rating scale (NRS) 3 (1–6 [0–9]) vs. 5 (3–7 [0–9]), p = 0.001; less bladder spasms (NRS 1 (0–2 [0–10]) vs. 2 (0–5 [0–10]), p = 0.001 and less sedation; NRS 2 (0–3 [0–10]) vs. 3 (2–6 [0–10]), p = 0.005. Moreover, the intervention group used less rescue medication. Pruritus was more severe in the intervention group; NRS 4 (1–7 [0–10]) vs. 0 (0–1 [0–10]), p = 0.000. We conclude that despite a modest increase in the incidence of pruritus, multimodal pain management with intrathecal bupivacaine/morphine remains a viable option for robot-assisted radical prostatectomy.     

Quadratus lumborum block for analgesia after caesarean section: a randomised controlled trial

Quadratus lumborum block has been shown to provide satisfactory analgesia after caesarean section performed under neuraxial anaesthesia. However, its efficacy has not been demonstrated in patients who have received intrathecal morphine. The aim of this study was to assess the efficacy of quadratus lumborum block as part of a multimodal analgesic regimen including intrathecal morphine. This was a prospective, double-blind, placebo-controlled trial. Participants were randomly allocated to receive bilateral quadratus lumborum block (40 ml levobupivacaine 0.25%) or sham block (control) after undergoing elective caesarean section under spinal anaesthesia. The primary outcome was 24-h morphine consumption measured by patient-controlled analgesia. Secondary outcomes included pain scores and quality of recovery. Data from 86 women were analysed. Median (IQR [range]) 24-h morphine consumption was similar in patients receiving quadratus lumborum block and sham block (12 (8–29 [0–68]) mg vs. 14 (5–25 [0–90]) mg, respectively; p = 0.986). There was a reduction in median (IQR [range]) visual analogue scale pain scores at 6 h with quadratus lumborum block compared with sham block both at rest (6 (0–14 [0–98]) mm vs. 14 (3–23 [0–64]) mm (p = 0.019); and on movement: 23 (10–51 [0–99]) mm vs. 44 (27–61 [2–94]) mm; (p = 0.014)). There was no difference in pain scores at any other time-point up to 48 h. When used in conjunction with intrathecal morphine and spinal anaesthesia, bilateral quadratus lumborum block does not reduce 24-h morphine consumption after caesarean section.     

The combined effects of midazolam and propofol sedation on muscle power

We performed a randomised, crossover study to investigate the effects of intravenous sedation on grip strength and bite force. Twenty male volunteers received a bolus intravenous injection of midazolam (0.02 mg.kg^?1) together with a 30‐min propofol infusion designed to achieve an effect‐site concentration of 1.0 μg.ml^?1. Observed variables included bispectral index, observer's assessment of alertness/sedation, correct answer rate of Stroop colour‐word test, grip strength and bite force. Grip strength decreased from a median (IQR [range]) of 483 (443–517 [380–586]) N to 358 (280–405 [108–580]) N (p < 0.001) during sedation and recovered following flumazenil administration, while bite force increased from 818 (593–1026 [405–1406]) N to 1377 (1243–1585 [836–2357]) N (p < 0.001) during sedation. Although bite force gradually returned to baseline following flumazenil administration, it remained increased throughout the experimental period. We conclude that bite force increased during intravenous sedation and that this may have clinical implications.     

A randomised controlled trial of fibrinogen concentrate during scoliosis surgery

Bleeding and blood transfusion are common after scoliosis surgery. Fibrinogen is essential for blood clot formation and depletes quickly during haemorrhage. We randomly allocated 102 children 12–18 years old having surgery for idiopathic scoliosis, 51 to intra-operative fibrinogen concentrate 30 mg.kg⁻¹ (maximum 2 g) and 51 to saline placebo. Fibrinogen reduced peri-operative blood loss by a median (95%CI) volume of 155 (5–320) ml, from a median (IQR [range]) of 1035 (818–1420 [400–3030]) ml to 885 (755–1155 [270–2645]) ml, p = 0.04. Seven and four children received allogeneic red blood cell transfusion after fibrinogen and placebo, respectively, p = 0.34. There were no side-effects.     

The ability of bispectral index to detect intra‐operative wakefulness during total intravenous anaesthesia compared with the isolated forearm technique

It has been suggested that monitoring during total intravenous anaesthesia should include aspects of brain function. The current study used a manually adjusted target‐controlled infusion of propofol for anaesthesia, guided to a bispectral index range of 55–60. Intra‐operative responsiveness, as assessed by the isolated forearm technique, was compared with whether the bispectral index predicted/identified a patient's appropriate hand movements in responses to commands. Twenty‐two women underwent major gynaecological surgery with total intravenous anaesthesia, propofol, remifentanil and atracurium. Sixteen women responded, on 80 occasions, with appropriate hand movements to commands during surgery, of which the bispectral index detected 47 (sensitivity 59%). The bispectral index suggested consciousness 220 times in the absence of movement responses (specificity 85%). The positive predictive value of a bispectral index response was 18%. While two women had vague recall about squeezing fingers, none had recall of surgery. For patients who responded more than once during surgery the bispectral index value associated with a response was not constant. Although there was no difference in the median (IQR [range]) effect site propofol concentration between intra‐operative responses (2.0 (1.5–2.3 [1.2–4.0]) μg.ml^?1) and eye opening after surgery (2.1 (1.7–2.8 [1.5–3.9]) μg.ml^?1), the median (IQR [range]) bispectral index value at eye opening after surgery was significantly higher than that associated with responses during surgery: 75 (70–78 [51–93]) vs 61 (52–67 [37–80]) respectively, (p < 0.001). The manual control of propofol intravenous anaesthesia to target a bispectral index range of 55–60 may result in an unacceptable number of patients who are conscious during surgery (albeit without recall).     

Microcirculation and haemodynamics after infraclavicular brachial plexus block using adrenaline as an adjuvant to lidocaine: a randomised,double-blind,crossover study in healthy volunteers

We evaluated the effect of adrenaline on human skin microcirculation (nutritive and sub-papillary) and systemic cardiovascular variables after it was added to lidocaine in infraclavicular brachial plexus blocks. Twelve healthy, non-smoking male volunteers were included, each attending two study sessions 2 weeks apart, and they were studied using a crossover design. In both sessions, they received an ultrasound-guided infraclavicular brachial plexus block in the non-dominant arm with 0.4 ml.kg⁻¹ lidocaine, 15 mg.ml⁻¹ with or without adrenaline 5 μg.ml⁻¹. Microcirculation was assessed by laser Doppler fluxmetry (sub-papillary blood flow), capillary video microscopy (nutritive blood flow) and continuous temperature measurements. Heart rate and arterial pressure were recorded continuously and non-invasively. Median (IQR [range]) sub-papillary blood flow increased substantially 30 min after the brachial plexus block, from 8.5 (4.4–13.5 [2.9–28.2]) to 162.7 (111.0–197.8 [9.5–206.7]) arbitrary units with adrenaline (p = 0.017), and from 6.9 (5.3–28.5 [1.8–42.1] to 133.7 (16.5–216.7 [1.0–445.0] arbitrary units without adrenaline (p = 0.036). Nutritive blood flow (functional capillary density, capillaries.mm⁻², measured at the dorsal side of the hand) decreased in the blocked extremity when adrenaline was used as adjuvant, from median (IQR [range]) 45 (36–52 [26–59]) to 38 (29–41 [26–42]), p = 0.028, whereas no significant change occurred without adrenaline. Median finger skin temperature (°C) increased by 44% (data pooled) with no significant differences between the groups. No significant changes were found in the systemic cardiovascular variables with or without adrenaline. We conclude that lidocaine infraclavicular brachial plexus blocks caused an increase in skin sub-papillary blood flow. The addition of adrenaline produced stronger and longer lasting blocks, but decreased the nutritive blood flow.     

Effects of ropivacaine concentration on the spread of sensory block produced by continuous thoracic paravertebral block: a prospective,randomised, controlled,double‐blind study

Factors affecting the distribution of continuous thoracic paravertebral block have never been examined. We designed this prospective, double‐blind study to check whether continuous thoracic paravertebral block with a higher ropivacaine concentration would provide a wider segmental sensory block spread. Sixty consecutive patients undergoing pulmonary lobectomy or segmentectomy were randomly allocated to receive continuous paravertebral infusion of either 0.2% or 0.5% ropivacaine (6 ml.h^?1). The primary outcome was the number of anaesthetised dermatomes as determined by loss of cold sensation 24 h after surgery. Twenty‐seven patients per group were included in the final analysis. The median (IQR [range]) number of anaesthetised dermatomes 24 h after surgery was 4 (3–6 [1–9]) with ropivacaine 0.2% and 4 (3–6 [2–11]) with ropivacaine 0.5% (p = 0.66). Contrary to our expectation, the segmental spread of sensory block produced by continuous thoracic paravertebral block does not depend on ropivacaine concentration.     

Comparison of analgesic efficacy of four‐quadrant transversus abdominis plane (TAP) block and continuous posterior TAP analgesia with epidural analgesia in patients undergoing laparoscopic colorectal surgery: an open‐label,randomised, non‐inferiority trial

Posterior transversus abdominis plane blocks have been reported to be an effective method of providing analgesia after lower abdominal surgery. We compared the efficacy of a novel technique of providing continuous transversus abdominis plane analgesia with epidural analgesia in patients on an enhanced recovery programme following laparoscopic colorectal surgery. A non‐inferiority comparison was used. Adult patients undergoing elective laparoscopic colorectal surgery were randomly assigned to receive continuous transversus abdominis plane analgesia (n = 35) vs epidural analgesia (n = 35), in addition to a postoperative analgesic regimen comprising regular paracetamol, regular diclofenac and tramadol as required. Sixty‐one patients completed the study. The transversus group received four‐quadrant transversus abdominis plane blocks and bilateral posterior transversus abdominis plane catheters that were infused with levobupivacaine 0.25% for 48 h. The epidural group received an infusion of bupivacaine and fentanyl. The primary outcome measure was visual analogue scale pain score on coughing at 24 h after surgery. We found no significant difference in median (IQR [range]) visual analogue scores during coughing at 24 h between the transversus group 2.5 (1.0–3.0 [0–5.5]) and the epidural group 2.5 (1.0–5.0 [0–6.0]). The one‐sided 97.5% CI was a 0.0 (∞–1.0) difference in means, establishing non‐inferiority. There were no significant differences between the groups for tramadol consumption. Success rate was 28/30 (93%) in the transversus group vs 27/31 (87%) in the epidural group. Continuous transversus abdominis plane infusion was non‐inferior to epidural infusion in providing analgesia after laparoscopic colorectal surgery.     

A randomised controlled trial comparing the GlideScope® and the Macintosh laryngoscope for double‐lumen endobronchial intubation

Double‐lumen endobronchial tubes are the most common method of achieving lung isolation and one‐lung ventilation during thoracic anaesthesia and surgery. We compared the clinical performance of the Macintosh laryngoscope and the GlideScope^® during endobronchial intubation with a double‐lumen tube. Seventy patients with no predictors for difficult laryngoscopy were allocated randomly to the Macintosh laryngoscope or GlideScope. The time taken for endobronchial intubation with the Macintosh laryngoscope was significantly shorter compared with that taken for the GlideScope, median (IQR [range]) 33 (22–52 [11–438]) s vs 70 (39–129 [21–242]) s, respectively, p = 0.0013. There was no statistical difference in the rate of success at the first attempt (91% vs 83%, respectively). On a numerical rating scale (scored from 0 to 10), the 30 anaesthetists who took part in the study rated endobronchial intubation overall as easier using the Macintosh compared with the GlideScope, 2 (1–3 [0–8]) vs 3 (2–6 [0–10]), respectively, p = 0.003. Postoperative voice changes were also less common in the Macintosh group (8 (22%) vs 17 (58%), p = 0.045). Anaesthetists found the GlideScope more difficult to use than the Macintosh laryngoscope and endobronchial intubation took longer; therefore, we cannot recommend its routine use with double‐lumen tubes in patients who are predicted to have a normal airway.     

The effects of prolonged inspiratory time during one‐lung ventilation: a randomised controlled trial

We evaluated the effects of a prolonged inspiratory time on gas exchange in subjects undergoing one‐lung ventilation for thoracic surgery. One hundred patients were randomly assigned to Group I:E = 1:2 or Group I:E = 1:1. Arterial blood gas analysis and respiratory mechanics measurements were performed 10 min after anaesthesia induction, 30 and 60 min after initiation of one‐lung ventilation, and 15 min after restoration of conventional two‐lung ventilation. The mean (SD) ratio of the partial pressure of arterial oxygen to fraction of inspired oxygen after 60 min of one‐lung ventilation was significantly lower in Group I:E = 1:2 compared with Group I:E = 1:1 (27.7 (13.2) kPa vs 35.2 (22.1) kPa, respectively, p = 0.043). Mean (SD) physiological dead space‐to‐tidal volume ratio after 60 min of one‐lung ventilation was significantly higher in Group I:E = 1:2 compared with Group I:E = 1:1 (0.46 (0.04) vs 0.43 (0.04), respectively, p = 0.008). Median (IQR [range]) peak inspiratory pressure was higher in Group I:E = 1:2 compared with Group I:E = 1:1 after 60 min of one‐lung ventilation (23 (22–25 [18–29]) cmH₂O vs 20 (18–21 [16–27]) cmH₂O, respectively, p < 0.001) and median (IQR [range]) mean airway pressure was lower in Group I:E = 1:2 compared with Group I:E = 1:1 (10 (8–11 [5–15]) cmH₂O vs 11 (10–13 [5–16]) cmH₂O, respectively, p < 0.001). We conclude that, compared with an I:E ratio of 1:2, an I:E ratio of 1:1 resulted in a modest improvement in oxygenation and decreased shunt fraction during one‐lung ventilation.     

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.     

Pulse pressure variation to predict fluid responsiveness in spontaneously breathing patients: tidal vs forced inspiratory breathing

We evaluated whether pulse pressure variation can predict fluid responsiveness in spontaneously breathing patients. Fifty‐nine elective thoracic surgical patients were studied before induction of general anaesthesia. After volume expansion with hydroxyethyl starch 6 ml.kg^?1, patients were defined as responders by a ≥ 15% increase in the cardiac index. Haemodynamic variables were measured before and after volume expansion and pulse pressure variations were calculated during tidal breathing and during forced inspiratory breathing. Median (IQR [range]) pulse pressure variation during forced inspiratory breathing was significantly higher in responders (n = 29) than in non‐responders (n = 30) before volume expansion (18.2 (IQR 14.7–18.2 [9.3–31.3])% vs 10.1 (IQR 8.3–12.6 [4.8–21.1])%, respectively, p < 0.001). The receiver‐operating characteristic curve revealed that pulse pressure variation during forced inspiratory breathing could predict fluid responsiveness (area under the curve 0.910, p < 0.0001). Pulse pressure variation measured during forced inspiratory breathing can be used to guide fluid management in spontaneously breathing patients.