John Carney

The analgesic efficacy of transversus abdominis plane block after cesarean delivery: a randomized controlled trial.

BACKGROUND:The transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing midline abdominal wall incisions. We evaluated its analgesic efficacy over the first 48 postoperative hours after cesarean delivery performed through a Pfannensteil incision, in a randomized controlled, double-blind, clinical trial. METHODS:Fifty women undergoing elective cesarean delivery were randomized to undergo TAP block with ropivacaine (n = 25) versus placebo (n = 25), in addition to standard postoperative analgesia comprising patient-controlled IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a standard spinal anesthetic, and at the end of surgery, a bilateral TAP block was performed using 1.5 mg/kg ropivacaine (to a maximal dose of 150 mg) or saline on each side. Each patient was assessed postoperatively by a blinded investigator: in the postanesthesia care unit and at 2, 4, 6, 12, 24, 36, and 48 h postoperatively. RESULTS:The TAP block with ropivacaine compared with placebo reduced postoperative visual analog scale pain scores. Mean (± sd) total morphine requirements in the first 48 postoperative hours were also reduced (66 ± 26 vs 18 ± 14 mg, P < 0.001), as was the 12-h interval morphine consumption up to 36 h postoperatively. The incidence of sedation was reduced in patients undergoing TAP blockade. There were no complications attributable to the TAP block. CONCLUSIONS:The TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia when compared with placebo block up to 48 postoperative hours after elective cesarean delivery.

The Transversus Abdominis Plane Block Provides Effective Postoperative Analgesia in Patients Undergoing Total Abdominal Hysterectomy

BACKGROUND:Patients undergoing total abdominal hysterectomy suffer significant postoperative pain. The transversus abdominis plane (TAP) block is a recently described approach to providing analgesia to the anterior abdominal wall. We evaluated the analgesic efficacy of the TAP block in patients undergoing total abdominal hysterectomy via a transverse lower abdominal wall incision, in a randomized, controlled, double-blind clinical trial. METHODS:Fifty females undergoing elective total abdominal hysterectomy were randomized to undergo TAP block with ropivacaine (n = 24) versus placebo (n = 26) in addition to standard postoperative analgesia comprising patient-controlled IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a general anesthetic and, before surgical incision, a bilateral TAP block was performed using 1.5 mg/kg ropivacaine (to a maximal dose of 150 mg) or saline on each side. Each patient was assessed postoperatively by a blinded investigator in the postanesthesia care unit and at 2, 4, 6, 12, 24, 36, 48 h postoperatively. RESULTS:The TAP block with ropivacaine reduced postoperative visual analog scale pain scores compared to placebo block. Mean (±sd) total morphine requirements in the first 48 postoperative hours were also reduced (55 ± 17 mg vs 27 ± 20 mg, P < 0.001). The incidence of sedation was reduced in patients undergoing TAP blockade. There were no complications attributable to the TAP block. CONCLUSIONS:The TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia when compared to placebo block up to 48 postoperative hours after elective total abdominal hysterectomy.

Studies on the spread of local anaesthetic solution in transversus abdominis plane blocks.

The extent of analgesia provided by transversus abdominis plane blocks depends upon the site of injection and pattern of spread within the plane. There are currently a number of ultrasound‐guided approaches in use, including an anterior oblique‐subcostal approach, a mid‐axillary approach and a more recently proposed posterior approach. We wished to determine whether the site of injection of local anaesthetic into the transversus abdominis plane affects the spread of the local anaesthetic within that plane, by studying the spread of a local anaesthetic and contrast solution in four groups of volunteers. The first group underwent the classical landmark‐based transversus abdominis plane block whereby two different volumes of injectate were studied: 0.3 ml.kg−1 vs 0.6 ml.kg−1. The second group underwent transversus abdominis plane block using the anterior subcostal approach. The third group underwent transversus abdominis plane block using the mid‐axillary approach. The fourth group underwent transversus abdominis plane block using the posterior approach, in which local anaesthetic was deposited close to the antero‐lateral border of the quadratus lumborum. All volunteers subsequently underwent magnetic resonance imaging at 1, 2 and 4 h following each block to determine the spread of local anaesthetic over time. The studies demonstrated that the anterior subcostal and mid‐axillary ultrasound approaches resulted in a predominantly anterior spread of the contrast solution within the transversus abdominis plane and relatively little posterior spread. There was no spread to the paravertebral space with the anterior subcostal approach. The mid‐axillary transversus abdominis plane block gave faint contrast enhancement in the paravertebral space at T12‐L2. In contrast, the posterior approaches, using both landmark and ultrasound identifications, resulted in predominantly posterior spread of contrast around the quadratus lumborum to the paravertebral space from T5 to L1 vertebral levels. We concluded that the pattern of spread of local anaesthetic differs depending on the site of injection into the transversus abdominis plane. This may have important implications for the extent of analgesia produced with each approach.

Ipsilateral transversus abdominis plane block provides effective analgesia after appendectomy in children: a randomized controlled trial.

BACKGROUND:The transversus abdominis plane (TAP) block provides effective postoperative analgesia in adults undergoing major abdominal surgery. Its efficacy in children remains unclear, with no randomized clinical trials in this population. In this study, we evaluated its analgesic efficacy over the first 48 postoperative hours after appendectomy performed through an open abdominal incision, in a randomized, controlled, double-blind clinical trial. METHODS:Forty children undergoing appendectomy were randomized to undergo unilateral TAP block with ropivacaine (n = 19) versus placebo (n = 21) in addition to standard postoperative analgesia comprising IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a standard general anesthetic, and after induction of anesthesia, a TAP block was performed using the landmark technique with 2.5 mg · kg−1 ropivacaine 0.75% or an equal volume (0.3 mL · kg−1) of saline on the ipsilateral side to the incision. RESULTS:The TAP block with ropivacaine reduced mean (±SD) morphine requirements in the first 48 postoperative hours (10.3 ± 12.7 vs 22.3 ± 14.7 mg; P < 0.01) compared with placebo block. The TAP block also reduced postoperative visual analog scale pain scores at rest and on movement compared with placebo. Interval morphine consumption was reduced over the first 24 postoperative hours. There were no between-group differences in the incidence of sedation or nausea and vomiting. There were no complications attributable to the TAP block. CONCLUSIONS:Unilateral TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia compared with placebo in the first 48 postoperative hours after appendectomy in children.

A comparison of the Glidescope®, Pentax AWS®, and Macintosh laryngoscopes when used by novice personnel: a manikin study

PurposeDirect laryngoscopic tracheal intubation is a potentially lifesaving procedure, but a difficult skill to acquire and maintain. The consequences of poorly performed intubation attempts are potentially severe. The Pentax AWS® and the Glidescope® are indirect laryngoscopes that may require less skill to use. We therefore hypothesized that AWS® and Glidescope® would prove superior to the Macintosh laryngoscope when used by novices in the normal and simulated difficult airway.MethodsIn this prospective randomized crossover trial following standardized didactic instruction, medical students with no prior experience of laryngoscopy performed tracheal intubation using each device. Each student was allowed up to three attempts to intubate in a Laerdal® Intubation Trainer in two laryngoscopy scenarios and in a Laerdal® SimMan® manikin in one scenario. The students then performed tracheal intubation of the normal airway a second time to characterize the learning curve for each device.ResultsThe Pentax AWS® provided better intubation conditions than the Glidescope® or the Macintosh, resulting in greater success of intubation, particularly in the difficult laryngoscopy scenarios. The Glidescope® demonstrated advantages over the Macintosh, particularly in the more difficult scenarios. Both the AWS® and the Glidescope® decreased the duration of intubation attempts, reduced the number of maneuvers required, and reduced the potential for dental trauma. In direct comparisons, the AWS® provided the best intubation conditions.ConclusionsThe Pentax AWS® appears to constitute a better alternative to the Macintosh for novice personnel to acquire the skills of tracheal intubation.RésuméObjectifL’intubation trachéale par laryngoscopie directe est une procédure potentiellement salutaire, mais il s’agit également d’une compétence difficile à acquérir et à maintenir. Les conséquences de tentatives d’intubation mal réalisées sont potentiellement graves. Le Pentax AWS® et le Glidescope® sont des laryngoscopes indirects qui pourraient nécessiter une compétence moindre. Ainsi, nous avons émis l’hypothèse que l’AWS® et le Glidescope® donneraient de meilleurs résultats que le laryngoscope Macintosh lors de leur utilisation par du personnel inexpérimenté pour l’intubation de voies aériennes normales ou rendues difficiles par simulation.MéthodeDans cette étude croisée randomisée et prospective qui a été menée à la suite d’une formation didactique standard, des étudiants en médecine n’ayant pas d’expérience antérieure en matière de laryngoscopie ont réalisé une intubation trachéale à l’aide de chacun des appareils. Chaque étudiant avait droit à un maximum de trois tentatives d’intubation sur un simulateur d’intubation Laerdal® dans le cadre de deux scénarios de laryngoscopie, dont l’un sur un mannequin Laerdal® SimMan®. Les étudiants ont ensuite réalisé une seconde intubation trachéale dans une voie aérienne normale afin de déterminer la courbe d’apprentissage de chaque appareil.RésultatsLe Pentax AWS® a procuré de meilleures conditions d’intubation que le Glidescope® ou le Macintosh, ce qui a eu pour résultat un taux de réussite de l’intubation plus élevé et ce, particulièrement dans les situations de laryngoscopie difficile. Le Glidescope® a démontré des avantages par rapport au Macintosh, notamment dans les situations de laryngoscopie plus difficile. L’AWS® et le Glidescope® ont permis de réduire la durée des tentatives d’intubation, le nombre de manœuvres nécessaires, ainsi que le potentiel d’un traumatisme dentaire. En comparaison directe, l’AWS® était le laryngoscope procurant les meilleures conditions d’intubation.ConclusionLe laryngoscope Pentax AWS® semble constituer une meilleure alternative au Macintosh pour permettre au personnel inexpérimenté d’acquérir les compétences nécessaires à l’intubation trachéale.

Effects and mechanisms of action of sildenafil citrate in human chorionic arteries

ObjectivesSildenafil citrate, a specific phosphodiesterase-5 inhibitor, is increasingly used for pulmonary hypertension in pregnancy. Sildenafil is also emerging as a potential candidate for the treatment of intra-uterine growth retardation and for premature labor. Its effects in the feto-placental circulation are not known. Our objectives were to determine whether phosphodiesterase-5 is present in the human feto-placental circulation, and to characterize the effects and mechanisms of action of sildenafil citrate in this circulation.Study DesignEx vivo human chorionic plate arterial rings were used in all experiments. The presence of phosphodiesterase-5 in the feto-placental circulation was determined by western blotting and immunohistochemical staining. In a subsequent series of pharmacologic studies, the effects of sildenafil citrate in pre-constricted chorionic plate arterial rings were determined. Additional studies examined the role of cGMP and nitric oxide in mediating the effects of sildenafil.ResultsPhosphodiesterase-5 mRNA and protein was demonstrated in human chorionic plate arteries. Immunohistochemistry demonstrated phosphodiesterase-5 within the arterial muscle layer. Sildenafil citrate produced dose dependent vasodilatation at concentrations at and greater than 10 nM. Both the direct cGMP inhibitor methylene blue and the cGMP-dependent protein kinase inhibitor Rp-8-Br-PET-cGMPS significantly attenuated the vasodilation produced by sildenafil citrate. Inhibition of NO production with L-NAME did not attenuate the vasodilator effects of sildenafil. In contrast, sildenafil citrate significantly enhanced the vasodilation produced by the NO donor sodium nitroprusside.ConclusionPhosphodiesterase-5 is present in the feto-placental circulation. Sildenafil citrate vasodilates the feto-placental circulation via a cGMP dependent mechanism involving increased responsiveness to NO.