Sang Kyi Lee

Isoflurane cracks the polycarbonate connector of extra-corporeal circuit -A case report-.

Cardiopulmonary bypass (CPB) is widely used for cardiac surgery by virtue of its proven safety over the course of its use during the past half century. Even though perfusion is safer, incidents still occur. During the repair of a ventricular-septal defect in an 11-month-old infant, we experienced a critical incident related to the potential hazardous effect of volatile anesthetics on the polycarbonate connector of extra-corporeal circuit. The damage to the polycarbonate connector had occurred after spillage of isoflurane during the filling of the vaporizer, causing it to crack and leak. The incident was managed by replacement of the cracked connector during a temporary circulatory arrest. The patient was hypothermic and the time off bypass was less than 1.5 min. There were no neurologic sequelae, the patient made an uneventful recovery. In conclusion, the spillage of volatile anesthetics can cause cracks in the polycarbonate connector of the extra-corporeal circuit, leading to potentially interruption of CPB.

A comparison of the consumption of inhaled anesthetics according to fresh gas flow and anesthetic circuits

BACKGROUND In the Korean National Health Insurance Corporation (KNHIC), payment for inhaled anesthetics are made according to the simulated dose and not the consumed dose. We compare the consumption of inhaled anesthetics according to fresh gas flow (FGF) and anesthetic circuits to compare the consumption of anesthetics and the guidelines for KNHIC payments. METHODS 161 patients were randomized into six groups who received isoflurane using a closed circuit (group I-C), a semi-closed circuit with FGF 3 L/min (group I-3), or 4 L/min (group I-4), as for the sevoflurane group (group S-C, S-3, and S-4). Mean arterial pressure (MAP) and heart rate (HR) were maintained within +/- 20% of baseline. Minimum alveolar concentration (MAC) and consumption of inhaled anesthetics were recorded by a new anesthetic machine. RESULTS There were no significant differences among the groups for MAP, HR, and MAC. During anesthesia maintenance, the mean consumption per 15 minutes of inhaled anesthetics was significantly lower in group I-C (1.0 +/- 0.3 ml) than in group I-3 (3.5 +/- 0.7 ml) and than group I-4 (4.9 +/- 0.9 ml) and similar to the sevoflurane groups (group S-C [1.3 +/- 0.4 ml] vs group S-3 [5.3 +/- 1.0 ml] vs group S-4 [6.9 +/- 1.3 ml], respectively; P < 0.05). CONCLUSIONS In sevoflurane groups, inhaled anesthetics were consumed more than in isoflurane groups. The KNHIC payment guidelines were close to the actual consumption of inhaled anesthetics under using a semi-closed circuit with FGF 3 L/min in sevoflurane and FGF 4 L/min in isoflurane.

A comparison of the temperature difference according to the placement of a nasopharyngeal temperature probe

Background The purpose of this study was to compare temperatures measured at three different sites where a nasopharyngeal temperature probe is commonly placed. Methods Eighty elective abdominal surgical patients were enrolled. After anesthesia induction, four temperature probes were placed at the nasal cavity, upper portion of the nasopharynx, oropharynx, and the esophagus. The placement of the nasopharyngeal temperature probes was evaluated using a flexible nasendoscope, and the depth from the nares was measured. The four temperatures were simultaneously recorded at 10-minute intervals for 60 minutes. Results The average depths of the probes that were placed in the nasal cavity, upper nasopharynx, and the oropharynx were respectively 5.7 ± 0.9 cm, 9.9 ± 0.7 cm, and 13.6 ± 1.7 cm from the nares. In the baseline temperatures, the temperature differences were significantly greater in the nasal cavity 0.32 (95% CI; 0.27-0.37)℃ than in the nasopharynx 0.02 (0.01–0.04)℃, and oropharynx 0.02 (−0.01 to 0.05)℃ compared with the esophagus (P < 0.001). These differences were maintained for 60 minutes. Twenty patients showed a 0.5℃ or greater temperature difference between the nasal cavity and the esophagus, but no patient showed such a difference at the nasopharynx and oropharynx. Conclusions During general anesthesia, the temperatures measured at the upper nasopharynx and the oropharynx, but not the nasal cavity, reflected the core temperature. Therefore, the authors recommend that a probe should be placed at the nasopharynx (≈ 10 cm) or oropharynx (≈ 14 cm) with mucosal attachment for accurate core temperature measurement.

Comparison between the index finger insertion and catheter-guided insertion techniques for airway placement of a ProSeal TM laryngeal mask by inexperienced personnel

BACKGROUND Insertion of a ProSeal(TM) laryngeal mask airway (PLMA(TM)) by experienced users was more successful with using a catheter-guided (CG) technique than a digital technique. The purpose of this study is to assess the efficacy of the CG insertion technique for a PLMA(TM) by inexperienced personnel. METHODS Forty patients aged 18-65 yr and who were undergoing general anesthesia were randomly allocated to the index finger (IF) or CG insertion techniques for PLMA(TM) insertion. The IF technique was performed with the routine insertion technique. The CG technique was performed using a catheter inserted PLMA(TM), which was primed into the drain tube of the PLMA(TM) with using a soft flexible catheter. Successful insertion was primarily judged by the clinical function of the airway. The number of insertion attempts and the insertion time were recorded. Postoperative airway morbidity (sore throat, dysphonia, dysphagia) was assessed at 24 hr postoperatively. RESULTS The success rate was similar between the groups (IF, 18/20; CG, 15/20). The successful insertion time (the time to provide an effective airway) was similar between the groups but the insertion time at the first attempt was shorter for the IF technique (IF, 21.6 +/- 5.3 s; CG, 27.4 +/- 10.3 s). There were no differences between the groups for the postoperative airway morbidity. CONCLUSIONS This study suggests that the CG insertion technique is not a useful alternative technique for inexperienced personnel.

Desflurane-induced hemodynamic changes in patients with diabetic cardiovascular autonomic neuropathy

BACKGROUND Diabetic cardiovascular autonomic neuropathy (CAN) causes perioperative cardiovascular instability. A rapid increase in the desflurane concentration induces tachycardia and hypertension (HTN). This study examined the effects of the cardiovascular response to desflurane on patients with diabetic CAN. METHODS Forty diabetes mellitus (DM) patients with CAN were divided two groups: one with HTN (DM+HTN group, n = 17) and one without HTN (DM group, n = 23). The control group (n = 20) was composed of healthy patients without DM or HTN. In each group, the concentration of desflurane inspired was increased abruptly to 12.0 vol% 2 minutes after a thiopental injection. The target was to produce an end-tidal concentration of desflurane of 10.0 vol%, which was maintained until the end of the study by adjusting the vaporizer dial setting. The heart rate (HR), mean arterial pressure (MAP), and cardiac index (CI) were measured. RESULTS The HR, MAP and CI increased significantly in all three groups when compared with the baseline (P<0.05). Additionally, the HR and MAP showed did not differ among the three groups at any of sampling times. However, the CI of the DM group and the DM+HTN group differed when compared with the control group at 90 and 120 seconds after intubation (P<0.05). CONCLUSIONS In diabetic patients with CAN, the hemodynamic responses to a rapid increase in desflurane concentration are similar to those in non-diabetic patients before endotracheal intubation. However, after endotracheal intubation, increments in CI are blunted in diabetic patients with CAN.