Alex Tiong Heng Sia

Comparison of the LMA Supreme vs the i‐gel™ in paralysed patients undergoing gynaecological laparoscopic surgery with controlled ventilation*

We compared the efficacy of the inflatable cuff of the LMA Supreme™ against the non‐inflatable i‐gel™ cuff in providing an adequate seal for laparoscopic surgery in the Trendelenburg position in 100 female patients. There was no difference in our primary outcome, oropharyngeal leak pressure, between the LMA Supreme and the i‐gel (mean (SD) 26.4 (5.1) vs 25.0 (5.7) cmH2O, respectively; p = 0.18). Forty‐seven (94%) LMA Supremes and 48 (96%) i‐gels were successfully inserted on the first attempt, with similar ease, and comparable times to the first capnograph trace (mean (SD) 14.3 (4.7) s for the LMA Supreme vs 15.4 (8.2) s for the i‐gel; p = 0.4). Gastric tube insertion was easier and achieved more quickly with the LMA Supreme vs the i‐gel (9.0 (2.5) s vs 15.1 (7.3) s, respectively; p < 0.001). After creation of the pneumoperitoneum, there was a smaller difference between expired and inspired tidal volumes with the LMA Supreme (21.5 (15.2) ml) than with the i‐gel (31.2 (23.5) ml; p = 0.009). There was blood on removal of two LMA Supremes and one i‐gel. Four patients in the LMA Supreme group and one patient in the i‐gel group experienced mild postoperative sore throat.

Comparison of three videolaryngoscopes: Pentax Airway Scope, C‐MAC™, Glidescope® vs the Macintosh laryngoscope for tracheal intubation

We compared the intubating characteristics of the Pentax Airway Scope, the C‐MAC™ and the Glidescope® with those of the Macintosh laryngoscope in 400 patients without predictors of difficult intubation. We found shorter intubation times with the Airway Scope (mean (SD) 20.6 (11.5) s) compared with the C‐MAC (31.9 (17.6) s) and Glidescope (31.2 (15.0) s), p < 0.001. The median (IQR [range]) score for ease of intubation was significantly lower (better) with the Airway Scope (0 (0–8.75 [0–60])) than with the C‐MAC (10 (0–20 [0–90])) or Glidescope (0 (0–20 [0–80])), p < 0.001. Ease of blade insertion in the C‐MAC (0 (0–0 [0–30])) was superior to that of the Airway Scope (0 (0–0 [0–70])), Macintosh (0 (0–0 [0–80])) or Glidescope (0 (0–10 [0–60])), p = 0.006. More patients had a grade 1 laryngeal view with the Airway Scope (97%) compared with the C‐MAC (87%), Glidescope (78%), or Macintosh (58%), p < 0.001. There were no grade 3 laryngeal views with the Airway Scope. The three videolaryngoscopes had comparable first attempt successful intubation rates: 95% for the Airway Scope, 93% for the C‐MAC and 91% for the Glidescope.

A randomized comparison of automated intermittent mandatory boluses with a basal infusion in combination with patient-controlled epidural analgesia for labor and delivery

BACKGROUND Automated mandatory boluses (AMB), when used in place of a continuous basal infusion, have been shown to reduce overall local anesthetic consumption without compromising analgesic efficacy in patient-controlled epidural analgesia (PCEA). We hypothesized that our PCEA+AMB regimen could result in a reduction of breakthrough pain requiring epidural supplementation in comparison with PCEA with a basal infusion (PCEA+BI). METHODS We recruited sixty-two healthy ASA I nulliparous parturients in early labor. The parturients were randomized to receive 0.1% ropivacaine+fentanyl 2 μg/mL either via PCEA+BI (PCEA with basal continuous infusion of 5mL/h) or PCEA+AMB (PCEA with AMB of 5 mL every hour instead of a basal infusion) immediately following successful induction of combined spinal-epidural (CSE) analgesia. Block characteristics, incidence of breakthrough pain requiring epidural supplementation, side effects, obstetric outcomes, Apgar scores and overall maternal satisfaction with analgesia were noted. RESULTS The time-weighted hourly consumption of ropivacaine (PCEA and clinician supplementation for breakthrough pain) was significantly lower in the PCEA+AMB group (mean=7.6 mL, SD 3.2) compared to the PCEA+BI group (mean=9.3 mL, SD 2.5; P<0.001). The mean time to first PCEA self-bolus following CSE was significantly longer in the PCEA+AMB group compared to the PCEA+BI group (268 min vs. 104 min; P<0.001). Parturients in Group PCEA+AMB also gave higher satisfaction scores. The incidence of breakthrough pain was similar in both groups. CONCLUSION PCEA+AMB, when compared to PCEA+BI, confers greater patient satisfaction and a longer duration of effective analgesia after CSE despite reduced analgesic consumption.

Optimal dose of intrathecal clonidine added to sufentanil plus bupivacaine for labour analgesia

Purpose: The combination of intrathecal (IT) 5µg sufentanil plus 1.25 mg bupivacaine is useful for inducing labour analgesia, albeit of short duration and slow onset. As a supplementation to this regimen, the effect of IT clonidine on the duration of analgesic action was investigated.Methods: Forty-eight healthy parturients were randomly assigned into three groups to receive 0µg (group C0), 15µg (C15) or 30µg (C30) of clonidine IT in addition to 5µg sufentanil plus 1.25 mg bupivacaine IT for labour analgesia. The quality of pain relief was assessed on 0-100 visual analogue scale by the author. The occurrence of side effects was also evaluated before the request for additional analgesia.Results: Clonidine (C15 and C30), produced a longer duration of analgesia than C0 (mean 144±sd 27.9, 165±31.8 vs 111±21.9 min,P<0.01). Also, C15 and C30 produced a more rapid onset and a higher quality of analgesia than C0, (P<0.01). The most cephalad level of sensory block was higher in C30 than C15 (median T3 vs T4,P<0.05) but lowest in C0 (median T7 vs T3,T4,P , 0.01). Side effects, sedation and hypotension, occurred more frequently in C30 than in either C0 or C15, (9 vs 2,5 and 9 vs 1,3, respectively,P<0.05).Conclusion: The optimal dose of intrathecal clonidine to enhance labour analgesia with the current sufentanil-bupivacaine regimen is 15µg. In view of the side effect profile, doses greater than 30µg clonidine are unlikely to be useful.RésuméObjectif: La combinaison de l’administration intrathécale (IT) de 5µg de sufentanil et de 1,25 mg de bupivacaïne est utile pour induire l’analgésie du travail obstétrial, quoique de courte durée et d’un lent délai d’installation. Comme apport complémentaire à ce régime, de la clonidine IT a été administrée et son effet sur la durée de l’action analgésique a été mesuré.Méthode: L’étude a porté sur 48 parturientes en bonne santé, réparties de façon aléatoire en trois groupes et qui ont reçu 0µg (groupe C0), ou 15µg (C15) ou 30µg (C30) de clonidine IT en plus de 5µg de sufentanil et de 1,25 mg de bupivacaïne IT comme analgésie pendant le travail. La qualité de l’analgésie a été évaluée par l’auteur sur une échelle visuelle analogique de 0–100. L’occurrence d’effets secondaires a aussi été notée avant la demande d’analgésie additionnelle.Résultats: Les doses de clonidine C15 et C30 ont produit une analgésie plus longue que la C0 (moyenne 144 ± écart type 27,9; 165±31,8 vs 111±21,9 min;P<0,01). De plus, C15 et C30 ont provoqué un début d’action plus rapide et une meilleure qualité d’analgésie que C0, (P<0,01). Le bloc sensitif le plus haut, en direction céphalique, a été obtenu avec C30 comparé à C15 (médiane T3 vs T4,P<0,05) et a étét plus bas avec C0 (médiane T7 vs T3, T4,P<0,01). Les effets secondaires, la sédation et l’hypotension, sont survenus plus souvent avec C30 qu’avec C0 ou C15, (9 vs 2,5 et 9 vs 1,3 respectivement,P<0,05).Conclusion: La dose optimale de clonidine intrathécale, nécessaire pour améliorer l’analgésie pendant le travail, combinée au régime habituel de sufentanil-bupivacaïne est de 15µg. En regard des effets secondaires, des doses de clonidine plus élevées que 30µg ne sont pas vraiment utiles.

A comparison between remifentanil and meperidine for labor analgesia: a systematic review.

BACKGROUND:Remifentanil is an ultrashort-acting opioid with favorable pharmacokinetic properties that make it suitable as a labor analgesic. Although it crosses the placenta freely, it is eliminated quickly in the neonate by rapid metabolism and redistribution. We aimed to determine whether remifentanil compared with meperidine is effective in reducing pain scores in laboring parturients. Other effects on the mother, the labor process, and the neonate were also examined. METHODS:MEDLINE, CINAHL, Embase, Cochrane CENTRAL, and Maternity and Infant Care databases were searched without language restriction using multiple keywords for labor analgesia, remifentanil, and meperidine. Published abstracts from 5 key research meetings and references from retrieved articles were examined for additional studies. Randomized controlled trials in laboring parturients comparing remifentanil with meperidine were selected. Risk of bias was assessed using criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We assessed for adequacy of sequence generation, allocation concealment, blinding, and completeness of follow-up. Data were extracted from each study using a standardized data collection form. The primary outcome was reduction in pain scores (visual analog scale [VAS], 0–100 mm). We also evaluated maternal side effects (sedation, oxygen desaturation, and bradypnea) and effects on the neonate (Apgar scores, umbilical cord pH, and Neurologic and Adaptive Capacity Scores). RESULTS:Seven studies (349 patients) were identified for inclusion; only 3 studies were suitable for quantitative synthesis in a meta-analysis (233 patients). We found that remifentanil reduces the mean VAS score at 1 hour by 25 mm more than meperidine (P < 0.001) (95% confidence interval = 19–31 mm). Limited conclusions can be made regarding the side-effect profile of remifentanil because of insufficient data. CONCLUSION:Compared with meperidine, remifentanil is superior in reducing mean VAS scores for labor pain after 1 hour.

Closed-loop double-vasopressor automated system vs manual bolus vasopressor to treat hypotension during spinal anaesthesia for caesarean section: a randomised controlled trial.

Hypotension necessitating vasopressor administration occurs commonly during caesarean section under spinal anaesthesia. We developed a novel vasopressor delivery system that automatically administers phenylephrine or ephedrine based on continuous non‐invasive arterial pressure monitoring. A phenylephrine bolus of 50 μg was given at 30‐s intervals when systolic blood pressure fell < 90% of baseline; an ephedrine bolus of 4 mg was given instead if systolic pressure fell < 90% of baseline together with a heart rate < 60 beats.min−1. The control group used manual boluses of either phenylephrine 100 μg or ephedrine 8 mg, administered at 1‐min intervals based on the same thresholds for systolic pressure and heart rate. This randomised, controlled, double‐blinded trial involved 213 healthy women who underwent elective caesarean delivery under spinal anaesthesia using 11 mg hyperbaric bupivacaine with 15 μg fentanyl and 100 μg morphine. The automated vasopressor group had better systolic pressure control, with 37/106 (34.9%) having any beat‐to‐beat systolic pressure reading < 80% of baseline compared with 63/107 (58.9%) in the control group (p < 0.001). There was no difference in the incidence of reactive hypertension, defined as systolic pressure > 120% of baseline, with 8/106 (7.5%) in the automated vasopressor group vs 14/107 (13.1%) in the control group, or total dose of vasopressors. The automated vasopressor group had lower median absolute performance error of 8.5% vs control of 9.8% (p = 0.013), and reduced incidence of nausea (1/106 (0.9%) vs 11/107 (10.3%), p = 0.005). Neonatal umbilical cord pH, umbilical lactate and Apgar scores were similar. Hence, our system afforded better control of maternal blood pressure and reduced nausea with no increase in reactive hypertension when compared with manual boluses.

The influence of ATP-binding cassette sub-family B member -1 (ABCB1) genetic polymorphisms on acute and chronic pain after intrathecal morphine for caesarean section: a prospective cohort study

BACKGROUND Polymorphisms of the ATP-binding cassette sub-family B member -1 (ABCB1) gene that codes for P-glycoprotein could influence the efflux of morphine from the central nervous system affecting its analgesic action. We investigated the effect of ABCB1 gene polymorphisms on analgesia and the development of persistent pain in post caesarean patients. METHODS Women of Chinese descent who received spinal anaesthesia with intrathecal morphine for elective caesarean section were recruited. They were given intravenous morphine via a patient-controlled analgesia pump for postoperative analgesia. Blood samples were collected and analysed for the presence of C1236T, G2677T/A and C3435T single nucleotide polymorphisms of the ABCB1 gene. We primarily investigated the association between ABCB1 polymorphisms and the effect of morphine. In a postpartum phone survey of the subjects six months after surgery, the occurrence of persistent abdominal wound scar pain was established. RESULTS We found no significant statistical difference in total morphine consumption, pain scores and side effects among the various genotypes. For C3435T polymorphism, there was a trend towards the association of the T allele and persistent pain for three months after surgery but this did not reach statistical significance (P=0.07). The TT genotype had the longest mean survival time of wound pain in comparison with CT and CC genotypes (P=0.004 and P=0.014, respectively). CONCLUSION Polymorphisms of ABCB1 were not associated with differences in morphine use in the first 24h after surgery. Women with the T allele of C3435T polymorphism showed a trend towards a higher risk of developing persistent postoperative pain.

Alkalinization of lidocaine does not hasten the onset of axillary brachial plexus block.

We assessed the onset of sensory and motor blockade as well as the distribution of sensory blockade after axillary brachial plexus block with 1.5% lidocaine hydrochloride 1:200,000 epinephrine with and without sodium bicarbonate in 38 patients. The onset of analgesia and anesthesia was recorded over the distributions of the median, ulnar, radial, and medial cutaneous nerves of the forearm, medial cutaneous and lateral cutaneous nerves of the arm, and musculocutaneous nerve. The onset of motor blockade of elbow and wrist movements was also recorded. Data were analyzed by using survival techniques and compared by using log rank tests. Only the onset of analgesia in the medial cutaneous nerves of the arm and forearm, and the onset of anesthesia in the medial cutaneous nerve of the arm were significantly faster (P < 0.05) with alkalinization of lidocaine. Our study showed that alkalinization of lidocaine does not significantly hasten block onset in most terminal nerve distributions. Implications: We examined whether alkalinizing a local anesthetic would quicken the onset of a regional upper limb nerve blockade. We found that alkalinization of lidocaine did not offer a significant clinical advantage in axillary brachial plexus blockade. (Anesth Analg 1998;86:566-8)

Randomised comparison of Pentax AirwayScope and Glidescope for tracheal intubation in patients with normal airway anatomy

We compared intubating characteristics of the Pentax AirwayScope and Glidescope in a randomised controlled trial involving 140 patients. We found significantly shorter intubation times with mean (SD) 21.3 (12.3) vs 30.2 (13.2) s, lower intubating difficulty scores 4.4 (10.4) vs 12.8 (16.3) p < 0.001, and better grade 1 laryngeal views with the Pentax AirwayScope (95.7 vs 81.4%, p = 0.015). Significantly more optimisation manoeuvres were needed to successfully intubate with the Glidescope, with significant inability to align the tip of the tracheal tube with the glottic opening with the Glidescope in 9 (13%) vs no patients, p = 0.013. There was more mucosal bleeding (4 (5.7%) vs 1 (1.4%), p = 0.366), more lip bleeding (3 (4.3%) vs 1 (1.4%), p = 0.620) and significantly more postoperative sorethroat, 13 (18.6%) vs 0, p < 0.001 associated with the Glidescope.

Closed‐loop double‐vasopressor automated system to treat hypotension during spinal anaesthesia for caesarean section: a preliminary study

Hypotension occurs in most caesarean sections under spinal anaesthesia, necessitating vasopressor administration. However, the optimal dosing regimen remains unclear. We have developed a novel vasopressor delivery system that automatically administers phenylephrine or ephedrine based on continuous non‐invasive blood pressure monitoring. This prospective cohort study recruited 55 healthy women under standardised spinal anaesthesia with 2.2 ml hyperbaric bupivacaine 0.5%, 15 μg fentanyl and 100 μg morphine. A 50‐μg phenylephrine bolus was given at 1‐min intervals when systolic blood pressure fell below 90% of baseline, and a 4‐mg ephedrine bolus was given when hypotension developed with bradycardia (heart rate <60 beats.min−1). Systolic blood pressure was within 20% of baseline in 88% of all measurements. Six patients (11%) had one or more measurements above 120% of baseline (1% of all measurements), whereas 36 (65%) had at least one reading below 80% of baseline (11% of total measurements). The system maintained systolic blood pressure at a mean (SD) of −9.1 (7.0)% below baseline, with 5.4 (2.5)% fluctuation. Two patients (4%) experienced pre‐delivery nausea. All 5‐min Apgar scores were 9.