Wendy H. L. Teoh

Colloid Preload Versus Coload for Spinal Anesthesia for Cesarean Delivery : The Effects on Maternal Cardiac Output

BACKGROUND: Spinal anesthesia for cesarean delivery may cause severe maternal hypotension, and a decrease in cardiac output (CO) and blood flow to the placenta. Fluid preloading with crystalloid is ineffective due to rapid redistribution. A “coload” given at the time of cerebrospinal fluid identification may be more effective. Our null hypothesis was that there would be no difference between the effect of a colloid preload (15 mL/kg hydroxyethyl starch (HES) 130/0.4 [Voluven® 6%]) and an identical coload on maternal CO and the incidence of hypotension after spinal anesthesia for cesarean delivery. Secondary outcomes studied were neonatal acid- base status and predelivery vasopressor requirements. METHODS: Forty ASA PS I and II women scheduled for elective cesarean delivery were recruited. Patients were randomized to Group P (preload of 15 mL/kg HES) or Group C (coload, given when cerebrospinal fluid identified). Heart rate, arterial blood pressure, stroke volume and CO measurements were recorded at baseline, every minute for 10 min, and every 2.5 min interval for 10 min with the USCOM™ ultrasonic CO monitor. Spinal anesthesia was performed at the L3/4 interspace in the right lateral position. Arterial blood pressure was maintained at 90%–100% of baseline values using IV phenylephrine boluses. RESULTS: Demographic, anesthetic, and surgical characteristics were similar. There were no between-group differences in baseline systolic blood pressure, heart rate, and colloid volume. CO and stroke volume were significantly increased in Group P (P = 0.01) in the 5 min after spinal anesthesia. This increase in CO was not sustained at 10 min. There were no significant between-group differences in the incidence of hypotension, absolute arterial blood pressure values (P = 0.73), predelivery median (range) phenylephrine requirements (300[0–1000] in Group P versus 150 [0–850]&mgr;g in Group C, P = 0.24), or neonatal outcome as measured by Apgar scores and umbilical arterial and venous blood gas values. CONCLUSION: Intravascular volume expansion with 15 mL/kg HES 130/0.4 given as a preload, but not coload, significantly increased maternal CO for the first 5 min after spinal anesthesia for cesarean delivery, however, maternal and neonatal outcomes were not different.

A randomised trial of the analgesic efficacy of ultrasound-guided transversus abdominis plane block after caesarean delivery under general anaesthesia.

Context Previous studies examining the efficacy of transversus abdominis plane block after caesarean section have mostly been in parturients under spinal anaesthesia. Objectives We postulated that the advantage of performing transversus abdominis plane block after caesarean section might be even more obvious after general anaesthesia, resulting in reduced 24-h consumption of morphine. Design, setting, patients and interventions In this single centre, randomised double-blind controlled trial, 40 women who underwent caesarean delivery under general anaesthesia were allocated randomly to receive a transversus abdominis plane block or no block. In those who received the block, 20 ml of levobupivacaine 2.5 mg ml−1 was deposited bilaterally into the transversus abdominis plane under ultrasound guidance using a Sonosite Titan (SonoSite, Bothell, Washington, USA) 7–13 MHz linear transducer at the end of surgery when the patient was still anaesthetised. Main outcome measures We recorded patient-controlled intravenous morphine use for 24 h, pain scores at rest and activity, sedation, nausea and vomiting, use of antiemetic medication and overall maternal satisfaction. The primary outcome was 24-h morphine consumption. Results Patients who received the transversus abdominis plane block used significantly less morphine in 24 h than those in the control group [12.3 (2.6) vs. 31.4 mg (3.1), P < 0.001) and had higher satisfaction scores [16 (80%) vs. 5 (25%), P = 0.012). There were no differences between groups in the visual analogue pain scores, sedation level, nausea and vomiting or the use of antiemetic medication. Conclusion Ultrasound-guided transversus abdominis plane block reduced morphine consumption following caesarean section under general anaesthesia, with increased maternal satisfaction.

A randomized controlled trial of three patient-controlled epidural analgesia regimens for labor.

BACKGROUND:Patient-controlled epidural analgesia (PCEA) is a safe and effective mode of maintaining labor analgesia; however, the ideal PCEA regimen is controversial. METHODS:In this prospective, randomized, double-blind study, we examined the analgesic efficacy of demand-only PCEA and PCEA with background infusion. We recruited 300 nulliparous parturients. Analgesia was initiated with intrathecal ropivacaine 2 mg and fentanyl 15 μg and maintained with epidural ropivacaine 0.1% with fentanyl 2 μg/mL. Parturients were randomized to one of three groups. Group 0: demand-only PCEA, bolus of 5 mL, lockout interval of 15 min. Group 5: background infusion of 5 mL/h, bolus of 5 mL, lockout interval of 12 min. Group 10: background infusion of 10 mL/h, bolus of 5 mL, lockout interval of 10 min. The maximum dose of all groups was 20 mL/h. The primary outcome was incidence of breakthrough pain. Secondary outcomes included intrapartum pain scores, neuraxial blockade characteristics, side effects, the total and hourly volume of ropivacaine, neonatal outcomes, and obstetric outcomes. RESULTS:The incidence of breakthrough pain and the maximum visual analog scale (0–100 mm scale) pain scores were higher in Group 0 versus Groups 5 and 10 (43% vs 17% and 11%, P < 0.001 and 37 ± 28 vs 22 ± 26 and 16 ± 25 [mean ± sd], P < 0.001), respectively. Group 10 had a longer duration of effective analgesia compared with Group 0 (mean 895 min, 95% CI 823–966 vs 565 min, 95% CI 454–677, P < 0.001) and increased ropivacaine consumption, and was associated with a longer duration of the second stage of labor. CONCLUSION:Demand-only PCEA (5-mL bolus, 15-min lockout interval) resulted in less local anesthetic consumption but an increased incidence of breakthrough pain, higher pain scores, shorter duration of effective analgesia, and lower maternal satisfaction, when compared with PCEA with background infusion (5-mL bolus, 10–12-min lockout interval, and 5–10 mL/h infusion).

Comparison of the GlideScope ® video laryngoscope vs. the intubating laryngeal mask for females with normal airways

Background and objective: In this randomized clinical study, we compared the intubation success rates of the intubating laryngeal mask airway with the GlideScope® in patients with normal airways. The primary hypothesis was that the intubating laryngeal mask airway was equally effective as the GlideScope® in terms of successful intubation times. Methods: Sixty ASA I and II adult patients undergoing elective gynaecological surgery were randomly allocated into either the intubating laryngeal mask airway group or the GlideScope® group. After a standard anaesthetic intravenous induction, orotracheal intubation was performed. Time taken for successful tracheal intubation, ease of device insertion, difficulty of tracheal intubation, manoeuvres needed to aid tracheal intubation, number of intubation attempts, haemodynamic changes every 2.5 min interval for 5 min and complications during tracheal intubation were recorded. Results: Time to successful intubation was longer (mean 68.4 s ± 23.5 vs. 35.7 s ± 10.7; P < 0.05), mean difficulty score was higher (mean 16.7 ± 16.3 vs. 7.3 ± 13.1; P < 0.05) and more intubation attempts were required in the intubating laryngeal mask airway group. Conclusion: The GlideScope® improved intubation time and difficulty score for tracheal intubation when compared with the intubating laryngeal mask airway in our patients. Blind intubation through the intubating laryngeal mask airway offers no advantages over the GlideScope® in patients with normal airways. Despite its limitations, the intubating laryngeal mask airway is a valuable adjunct, especially in cases of difficult airway management when it can provide ventilation in between intubation attempts.

Hyperbaric Bupivacaine 2.5 mg Prolongs Analgesia Compared with Plain Bupivacaine When Added to Intrathecal Fentanyl 25 g in Advanced Labor

We investigated the effect of sequential administration of intrathecal (IT) hyperbaric bupivacaine (after the initial administration of IT hypobaric fentanyl) on the duration of spinal analgesia. Thirty-seven nulliparous parturients with a cervical dilation ≥5 cm were randomized to receive either IT fentanyl 25 &mgr;g and plain bupivacaine 2.5 mg (group P; n = 19) or IT fentanyl 25 &mgr;g and hyperbaric (with 8% glucose) bupivacaine 2.5 mg (group H; n = 18). The two components of the IT injectate were administered sequentially (fentanyl 25 &mgr;g diluted in 2 mL of normal saline, immediately followed by 0.5 mL of 0.5% bupivacaine). Patients were then positioned with their torso elevated at 30° for 30 min. Pain scores using 0–100 visual analog scales were collected before combined spinal/epidural analgesia and at 5, 15, and 30 min after the block. Patients in Group H had a longer median duration of analgesia (122 min; range, 80–210 min) than Group P (95 min; range, 75–125 min) (P < 0.01). Group H also had a more limited dermatomal spread (median highest sensory level of T8 versus T4 in group P; P < 0.05). The side-effect profile was similar. Under these circumstances, hyperbaric bupivacaine conferred an increased duration of IT analgesia compared with plain bupivacaine.

Essential ultrasound techniques of the pediatric airway.

Ultrasound of the airways is a technique which has been described in a number of recent articles and reviews highlighting the diagnostic possibilities and simple methodology. However, there is a paucity of information focusing specifically on such methods in children where equipment, technique, and challenges are different. This review article gives a general overview of the equipment considerations, scanning protocols, and clinical applications in children.

Comparison of an equal-dose spinal anesthetic for cesarean section and for post partum tubal ligation

BACKGROUND We postulated that a spinal dose of hyperbaric bupivacaine 12 mg and morphine 100 microg administered for cesarean section would yield an equivalent sensory block height and provide sufficient analgesia if administered within 48 h of delivery for postpartum tubal ligation. METHOD 20 women undergoing postpartum tubal ligation (PPTL) within 48 h of vaginal delivery and 20 undergoing cesarean section (CS) were recruited. Spinal anesthesia was induced with intrathecal hyperbaric bupivacaine 12 mg and morphine 100 microg at L3/4 with patients in the right lateral position. RESULTS Baseline demographics of groups were comparable, but tubal ligation patients had greater parity, with a mean+/-SD 14.5+/-7.5 h from delivery to spinal anesthesia, and shorter duration of surgery, 21.4+/-7.6 vs. 35.3+/-11.3 min. Maximal sensory block was higher in group CS than PPTL, T2 (T1-T4) vs. T3 (T2-T5), P=0.001; time to reach maximal level did not differ significantly, (6.9+/-3.9 vs. 8.7+/-2.8 min, P=0.091). There was no difference in time for spinal block to recede two segments or to T10, and for motor block recovery to Bromage 2, all P>0.05. More CS patients were hypotensive (80% vs. 45%, P=0.048) and had intraoperative nausea (25% vs. 0%, P=0.047), but mean phenylephrine and ephedrine usage did not differ significantly. CONCLUSION An equivalent dose of hyperbaric bupivacaine 12 mg and morphine 100 microg for both CS and PPTL resulted in a higher sensory block, more hypotension and nausea in CS patients. The studied regimen might be appropriate for PPTL, but appears excessive for CS.

Use of extraglottic airways in patients undergoing ambulatory laparoscopic surgery without the need for tracheal intubation

Background: Second generation extraglottic airway devices with gastric access and separate breathing channels have ushered in a new era where their use is increasingly prevalent in surgical patients who would have been traditionally intubated for general anesthesia. New innovations like the i-gel, which is constructed of a thermoplastic elastomer, provide an airtight seal around patients perilaryngeal anatomy without the inflatable cuff mechanism found in the laryngeal mask airway supreme (LMAS). Methods: We conducted a randomized controlled trial comparing the LMAS with the i-gel in 70 anesthetized paralyzed patients undergoing laparoscopic female sterilization. Our primary outcome measure was the oropharyngeal leak pressure (OLP). We studied secondary outcomes of successful first attempt insertion rates, time and ease of the airway and gastric tube insertion, leak fractions and pharyngeal morbidity. Results: We found no difference in the OLP between LMAS and i-gel, 25.9 (4.2) versus 24.4 (4.3) s, P=0.153. Both devices had similar first attempt insertion rates (LMAS 94% vs. i-gel 91%) with similar ease and comparable times to achieve an effective airway, LMAS 14.7 (2.7) versus i-gel 16.5 (9.6) s, P=0.306, although gastric tube insertion was easier and faster for the LMAS, 7.9 (1.9) versus i-gel 14.8 (7.7) s, P<0.005. Intraoperatively, there was a significantly greater leak fraction with the i-gel of 0.06 (0.03) versus 0.04 (0.02) with the LMAS, P=0.013. Three patients (8.6%) with LMAS had mild sore throat; one patient (2.9%) had mucosal injury. No complications were documented in the i-gel group. Conclusions: Both these extraglottic airway devices offer similar OLPs, high insertion success rates at the first attempt with similar ease and insertion times (albeit longer gastric tube insertion with i-gel). Both provided effective ventilation despite a higher leak fraction with i-gel that was clinically inconsequential.

Ultrasonography: Heralding a New Era in Airway Management

Ultrasound (US) can help anesthesiologists locate the cricothyroid membrane before managing a difficult airway, rule out an intraoperative pneumothorax, locate the optimal level for elective dilatational tracheostomy, distinguish between tracheal and esophageal intubation before initiation of ventilation, and help clinicians overcome many other challenges related to the upper and lower airways. Indeed, the availability of easily transportable ultrasound machines, combined with increasing familiarity with the use of this technology, now makes ultrasonography a fundamental tool in airway management.

Videolaryngoscopy and Indirect Intubating Aids in Airway Management

The use of videolaryngoscopy has been incorporated into the latest revised 2013 American Society of Anesthesiologists Difficult Airway Algorithm, not only as a rescue device, but also as an initial approach to intubation. This chapter provides an overview of some popular videolaryngoscopes and indirect intubating aids which a body of evidence in the literature supports. We outline how videolaryngoscopy differs from direct laryngoscopy, the advantages and disadvantages, tips on how to improve the success of intubation, and how to document when using a videolaryngoscope. The individual characteristics of the Glidescope, CMAC, Pentax Airway Scope, McGrath MAC and McGrath series 5, Airtraq, King Vision, Venner AP Advance, intubating LMA Fastrach and C-Trach, Bonfils, Shikani, Levitan optical stylets are further expounded, with instruction and clinical tips for usage. Their clinical efficacy in the literature, problems and complications, and keypoints are summarized.