Yong Beom Kim

Acid–base alterations during laparoscopic abdominal surgery: a comparison with laparotomy

BACKGROUND Carbon dioxide insufflation during laparoscopic surgery results in an acid-base imbalance. The purpose of this study was to investigate the effect of pneumoperitoneum on the acid-base status using Stewarts approach. METHODS Thirty patients undergoing abdominal surgery were allocated to the laparotomy group (n=15) or the laparoscopy group (n=15). The acid-base parameters were measured 10 min after the induction (T1), 40 min after opening the peritoneum or pneumoperitoneum according to the group (T2), at the end of the surgery (T3), and 1 h after the surgery (T4). RESULTS There were no significant differences in the standard base excess (SBE), strong ion gap, or anion gap between the two groups. In both groups, the SBE decreased at T2, T3, and T4 compared with baseline value. At T3 and T4 in the laparotomy group, the apparent strong ion difference (SIDa) and pH were decreased whereas the lactate and chloride were increased compared with their baseline values. At T2 in the laparoscopy group, the pH was decreased whereas Pa(CO(2)) was increased compared with their baseline values. CONCLUSIONS The decrease in the pH during the pneumoperitoneum was affected by the increase in Pa(CO(2)), which promptly returned to a normal value after the desufflation. On the other hand, the decrease in the pH after laparotomy was affected by the metabolic factors, which persisted an hour after the surgery.

The optimum bolus dose of remifentanil to facilitate laryngeal mask airway insertion with a single standard dose of propofol at induction in children.

The purpose of this study was to determine the optimal bolus dose of remifentanil required for the successful insertion of the laryngeal mask airway during propofol induction in children without a neuromuscular blocking agent. Twenty‐six paediatric patients, aged 3–10 years, requiring anaesthesia for short ambulatory surgery were recruited. A predetermined bolus dose of remifentanil was injected over 30 s, followed by propofol 2.5 mg.kg−1 over 10 s. The bolus dose of remifentanil was determined by a modified Dixon’s up‐and‐down method, starting from 0.5 μg.kg−1 (0.1 μg.kg−1 as a step size). Laryngeal mask insertion was attempted 90 s after the end of remifentanil injection and the response of patients was classified as either ‘movement’ or ‘no movement’. The bolus dose of remifentanil at which there was a 50% probability of successful laryngeal mask insertion (ED50) during induction with 2.5 mg.kg−1 propofol was 0.56 (0.07) μg.kg−1 in children without a neuromuscular blocking agent. From probit analysis, the ED50 and ED95 of remifentanil were 0.52 μg.kg−1 (95% confidence limits, 0.42–0.62 μg.kg−1) and 0.71 μg.kg−1 (95% confidence limits, 0.61–1.40 μg.kg−1), respectively.

The effect of pressure-controlled ventilation on pulmonary mechanics in the prone position during posterior lumbar spine surgery: a comparison with volume-controlled ventilation.

Background: When an anesthetized patient is turned to the prone position using the Wilson frame, dynamic compliance (Cdyn) decreases and peak airway pressure (Ppeak) increases. As pressure-controlled ventilation (PCV) decreases the Ppeak, this prospective, randomized study was designed to compare the effect of PCV and volume-controlled ventilation (VCV) on lung mechanics in the prone position using the Wilson frame during posterior lumbar spine surgery. Methods: Forty patients scheduled for posterior lumbar spine surgery were randomly allocated to receive mechanical ventilation using either the VCV (n=20) or PCV (n=20) mode. Respiratory variables (including Ppeak and Cdyn) and oxygenation parameters were recorded at the supine position (Tsupine) and 30 minutes after prone positioning (Tprone). Results: During the study period, tidal volume, minute volume, end-tidal carbon dioxide tension, and positive end-expiratory pressure were comparable between the 2 groups. The Ppeak in the PCV group was lower than that in the VCV group throughout the study period (P=0.007 and 0.003 at Tsupine and Tprone, respectively) and was increased at Tprone compared with Tsupine in both groups. Cdyn was decreased from Tsupine to Tprone in both groups. However, the Cdyn in the PCV group was higher than that in the VCV group during the study period. The arterial oxygen tension was comparable between the 2 groups during the study period. Conclusions: PCV provides lower Ppeak compared with VCV when the ventilator is set to deliver the same tidal volume and variable respiratory rate to maintain a constant end-tidal carbon dioxide tension in patients undergoing posterior lumbar spine surgery in the prone position using the Wilson frame.

Extrapyramidal side effects after metoclopramide administration in a post-anesthesia care unit -A case report-

Although the incidence of extrapyramidal reactions associated with metoclopramide has been reported to be approximately 0.2%, such reactions are rare in the anesthetic field. Several anesthetic adjuvants, including ondansetron and pregabalin, have also been associated with extrapyramidal side effect. Here, the authors report the case of a 47-year-old patient, previously administered pregabalin and ondansetron, who developed extrapyramidal side effects after a single injection of metoclopramide (10 mg) in a post-anesthesia care unit.

Intubation without use of stylet for McGrath videolaryngoscopy in patients with expected normal airway: A randomized noninferiority trial

Background:During McGrath videolaryngoscope (VL) intubation, a styletted endotracheal tube maintaining an upward distal tip angle is recommended by some manufacturers. However, a styletted endotracheal tube can elicit rare but potentially serious complications. The purpose of this study was to demonstrate that a nonstyletted tube with exaggerated curvature would be noninferior to a styletted tube for orotracheal intubation using McGrath VL in patients with expected normal airway, by comparing the time to intubation and ease of intubation. Methods:One hundred forty patients, ages 19 to 70 years (American Society of Anesthesiologists physical status I–II), undergoing tracheal intubation for elective surgery were randomly allocated to the nonstylet group (n = 70) or the stylet group (n = 70). Anesthesia induction consisted of propofol, remifentanil, and rocuronium. The primary outcome was time to intubation assessed by a blind observer. Cormack and Lehane glottic grade, easy of intubation, and intubation difficulty score (IDS) were also assessed. Results:Median time to intubation [interquartile range] was not different between the nonstylet group and the stylet group (26 [24–32.5] s vs 27 [25–31] s, P = 0.937). There was no significant in median IDS between the nonstylet group and the stylet group (P = 0.695). Conclusion:This study shows that a nonstyletted endotracheal tube with exaggerated curvature has a similar performance to a styletted tube with a hockey-stick curvature during intubation using McGrath VL regarding time taken to successful intubation and easiness of intubation.

Effects of Presynaptic Muscarinic Receptor Blockade on Neuromuscular Transmission as Assessed by the Train-of-Four and the Tetanic Fade Response to Rocuronium

This study investigated the effect of muscarinic M1 and M2 receptor antagonists on the rocuronium‐induced train of four (TOF) fade and tetanic fade, respectively. Ex‐vivo phrenic nerves and diaphragms were obtained from adult Sprague‐Dawley rats and stabilized in Krebs buffer; the nerve‐stimulated muscle TOF fade was observed at 20 s intervals. For the TOF study, phrenic nerves and diaphragms were incubated with pirenzepine (an M1 blocker) at concentrations of 0 nmol L−1 (control), 10 nmol L−1 (PZP10), or 100 nmol L−1 (PZP100). Rocuronium was then administered incrementally until the first twitch tension had depressed by >95% during TOF stimulation. The mean TOF ratios were compared when the first twitch tensions were depressed by 40%‐50%. For the tetanic fade study, 50 Hz/5 s tetani was applied initially, 30 min after the administration of a loading dose of rocuronium and methoctramine (an M2 receptor blocker, loaded at 0 μmol L−1 [control], 1 μmol L−1 [MET1], or 10 μmol L−1 [MET10]). The EC95 of rocuronium was significantly lower in the PZP10 group than in the control group. In the PZP10 group, the TOF ratios at 50% and first twitch tension depression were significantly lower than those in the control group (P=.02). During tetanic stimulation, the tetanic fade was significantly enhanced in the MET10 group compared to the other groups. This study shows that antagonists of muscarinic M1 and M2 receptors affect the rocuronium‐induced neuromuscular block as demonstrated by the reduced EC95 and TOF ratios (M1 antagonist, pirenzepine) or the enhanced 50‐Hz tetanic fade (M2 antagonist, methoctramine).

Effect of pneumoperitoneum on the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic surgery.

Background This study investigated the effect of pneumoperitoneum on the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic abdominal surgery. Methods Thirty adult patients undergoing laparoscopic abdominal surgery were studied. Anesthesia was induced with 1.5 mg/kg of propofol, 12 ug/kg of alfentanil and 0.6 mg/kg of rocuronium and maintained with 2 vol% of sevoflurane and 0.05-0.2 µg/kg/min remifentanil. The neuromuscular relaxation was monitored by Train-of-Four (TOF) and post-tetanic count (PTC). Additional rocuronium of 0.2 mg/kg was administered for deep neuromuscular blockade at 30 min after pneumoperitoneum. Before (PPpre) and 30 min after pneumoperitoneum (PPpost), PTC was measured at 6 min intervals. The relationship between PTC and the time interval to reappearance of T1 response was observed. Results The mean ± SD of the intervals between the detection of 4 counts of the PTC and the first response to TOF stimulation was 13.0 ± 1.1 min and 16.4 ± 6.3 min PPpre and PPpost, respectively (P = 0.20). There were significant negative relationships between PTC observed and the time interval to reappearance of T1 response (adjusted R2 = 0.869, P < 0.001 for PPpre data, and adjusted R2 = 0.561, P < 0.001 for PPpost data). Comparing the difference of regression equation between PPpre and PPpost data using a parallelism test, there was no statistically significant difference (P = 0.193). Conclusions This study showed that PP with intra-abdominal pressure at the level of 13-14 mmHg did not affect the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic abdominal surgery.

Effects of adenosine receptor agonist on the rocuroniuminduced neuromuscular block and sugammadex-induced recovery

Background Several types of receptors are found at neuromuscular presynaptic membranes. Presynaptic inhibitory A1 and facilitatory A2A receptors mediate different modulatory functions on acetylcholine release. This study investigated whether adenosine A1 receptor agonist contributes to the first twitch tension (T1) of train-of-four (TOF) stimulation depression and TOF fade during rocuronium-induced neuromuscular blockade, and sugammadex-induced recovery. Methods Phrenic nerve-diaphragm tissues were obtained from 30 adult Sprague-Dawley rats. Each tissue specimen was randomly allocated to either control group or 2-chloroadenosine (CADO, 10 μM) group. One hour of reaction time was allowed before initiating main experimental data collection. Loading and boost doses of rocuronium were sequentially administered until > 95% depression of the T1 was achieved. After confirming that there was no T1 twitch tension response, 15 min of resting time was allowed, after which sugammadex was administered. Recovery profiles (T1, TOF ratio [TOFR], and recovery index) were collected for 1 h and compared between groups. Results There were statistically significant differences on amount of rocuronium (actually used during experiment), TOFR changes during concentration-response of rocuronium (P = 0.04), and recovery profiles (P < 0.01) of CADO group comparing with the control group. However, at the initial phase of this experiment, dose-response of rocuronium in each group demonstrated no statistically significant differences (P = 0.12). Conclusions The adenosine A1 receptor agonist (CADO) influenced the TOFR and the recovery profile. After activating adenosine receptor, sugammadex-induced recovery from rocuronium-induced neuromuscular block was delayed.

The effect of magnesium sulfate concentration on the effective concentration of rocuronium, and sugammadex-mediated reversal, in isolated left phrenic nerve hemi-diaphragm preparations from the rat

Background Perioperative magnesium sulfate (MgSO4) is used for analgesic, anti-arrhythmic, and obstetric purposes. The effects of MgSO4 on the neuromuscular blockade (NMB) induced by rocuronium, and the sugammadex reversal thereof, have not been clearly quantified. We investigated the effect of various MgSO4 concentrations on the NMB by rocuronium, and sugammadex reversal, in isolated left phrenic nerve hemi-diaphragm (PNHD) preparations from the rat. Methods Rat PNHD preparations were randomly allocated to one of four groups varying in terms of MgSO4 concentration (1, 2, 3, and 4 mM, each n = 10, in Krebs solution). The train-of-four (TOF) and twitch height responses were recorded mechanomyographically. The preparations were treated with incrementally increasing doses of rocuronium and each group’s effective concentration (EC)50, EC90, and EC95 of rocuronium were calculated via nonlinear regression. Then, sugammadex was administered in doses equimolar to rocuronium. The recovery index, time to T1 height > 95% of control, and the time to a TOF ratio > 0.9 after sugammadex administration were measured. Results The EC50, EC90, and EC95 of rocuronium fell significantly as the magnesium level increased. The EC50, EC90, and EC95 of rocuronium did not differ between the 3 and 4 mM groups. The recovery index, time to T1 height > 95% of control, and time to a TOF ratio > 0.9 after sugammadex administration did not differ among the four groups. Conclusions Increases in the magnesium concentration in rat PNHD preparations proportionally enhanced the NMB induced by rocuronium but did not affect reversal by equimolar amounts of sugammadex.

Effects of neuromuscular presynaptic muscarinic M1 receptor blockade on rocuronium-induced neuromuscular blockade in immobilized tibialis anterior muscles

This in vivo study tested the hypothesis that the modulation of acetylcholine (ACh) release by the M1 muscarinic receptor (mAChR) in the neuromuscular junction of disused muscles may affect the tensions of the muscles during the neuromuscular monitoring of a rocuronium‐induced neuromuscular block and compared the results with those obtained from normal muscles. A total of 20 C57BL/6 (wild‐type) and 10 α7 knock out (α7KO) mice were used in this experiment. As a pre‐experimental procedure, knee and ankle joints of right hind limbs were fixed by needle pinning at the 90° flexed position. After 2 weeks, the main experiment was performed. Both tendons of the tibialis anterior (TA) muscles were obtained, and the muscle tensions were recorded while the dose‐responses of rocuronium were measured three times in the same mouse by the serial administration of pirenzepine (0, 0.001 and 0.01 μg/g). Weight losses were observed after 2 weeks of immobilization in both groups, and a decrease in the mass of TA muscles at the immobilized side was observed compared to those of the contralateral nonimmobilized side. Tension depression of the TA muscles at immobilized side of the α7KO group was faster than those of the wild‐type group, but these differences decreased after the administration of pirenzepine. The tension depressions were similar regardless of the pirenzepine doses at the same side in the group. Tension depression may become more rapid in the α7 AChR‐expressed disused muscles by the decreased release of ACh release upon neuronal firing by the blockade of facilitatory M1 mAChR