Measurement of Auto-PEEP in Anesthetized Patients Using a Laser-Flex Endotracheal Tube with Changes in Respiratory Rates and Tidal Volume / 대한마취과학회지

BACKGROUND: The aim of the present study was to detect and quantify auto-positive end-expiratory pressure (auto-PEEP) in anesthetized patients using a Laser-Flex endotracheal tube (Mallincrodt, ID, 6.0 mm), by comparing the effects of changes in tidal volume and respiratory rate. METHODS: All patients (n = 30) undergoing elective surgery were anesthetized, paralyzed and intubated with a ID 8.0 mm endotracheal tube (n = 10, control), ID 6.0 mm endotracheal tube (n = 10, group S), or ID 6.0 mm Laser-Flex endotracheal tube (n = 10, group L), respectively. After anesthetic induction, ventilator settings using a Siemens Servo 900C were changed for a tidal volume of 8, 10 ml/kg, respiratory rates of 10, 12 or 14 breaths/min. Peak airway pressure was measured and auto-PEEP was quantified using an end-expiratory occlusion method. Data recorded on the Bicore CP-100 pulmonary monitor was transfered to a PC and analyzed by processing software (ANADAT). RESULTS: In group S and L, peak airway pressure and auto-PEEP were higher than control group and increased during an increase in tidal volume (P < 0.05). But they were increased significantly during an increase of respiratory rate, only when the tidal volume was 10 ml/kg (P < 0.05). CONCLUSIONS: There was an increase of auto-PEEP in anesthetized patients using a Laser-Flex endotracheal tube during incremental changes of tidal volume and respiratory rates.

Comparison between Laryngeal Mask Airway and Uncuffed Tracheal Tube for Positive Pressure Ventilation in Paralyzed Pediatric Patients: A Randomized Crossover Study / 대한마취과학회지

BACKGROUND: This randomized cross over study was performed to compare the effect of positive pressure ventilation (PPV) through a laryngeal mask airway (LMA) with that through an uncuffed endotracheal tube (ETT) in paralyzed pediatric patients. Additionally, this study was to determine the protective effect of LMA for the aspiration of oral secretion. METHODS: Pediatric patients (n = 158) weighing less than 30 kg, of ASA physical status 1 or 2 were studied. LMA or ETT was randomly selected and connected to a volume-type ventilator. After measurement and extubation, the other that was not initially used was inserted. Expiratory tidal volume (VT) and airway pressure were measured at the same ventilator setting by a simple pneumo-tachometer, and the expiratory tidal volume ratio (VTR) was calculated as expiratory VT of LMA/expiratory VT of ETT. In randomly selected 39 patients out of 158, methylene blue diluted 1:10 with saline was injected into the oral cavity during PPV through an LMA. At the end of the surgery, fiberoptic bronchoscopy was performed to observe any staining of methylene blue in the trachea. RESULTS: Successful placement of the LMA was achieved in 98% (155/158) of the cases. Expiratory VT through the LMA 1 or 1.5 was decreased if compared with that through the ETT. Leaking pressure of the LMA was lower than that of the ETT except LMA 2.5. VTR of the LMA size 1, 1.5, 2 and 2.5 (mean +/- SD) was respectively 0.94 +/- 0.22, 0.94 +/- 0.14, 1.02 +/- 0.18 and 1.06 +/- 0.19. There was no patient whose trachea was soiled with methylene blue. CONCLUSIONS: Only in older children who are indicated for LMA 2.5, did LMA have the same leakage and the same leaking pressure as ETT during PPV. LMA may not be recommended for the maintenance of PPV in young children less than 10 kg. Inflated LMA seems to have a protective effect against oral secretion.

Effect of Saline-Filled or Viscous Lidocaine-Filled Cuff on the Laser-Induced Polyvinyl Chloride Endotracheal Tube Fires and Tidal Volume / 대한마취과학회지

BACKGROUND: There have been a lot of methods that prevent catatrophic airway fires during laser surgery, but none of them can protect endotracheal tube cuff exposed directly to laser beam. This study was performed to know the preventive effect of viscous lidocaine-filled cuffs on laser-induced combustion, and to know how long we can maintain positive pressure ventilation if laser beam broke out cuff perforation. METHODS: Transparent acrylic trachea attached to artificaial lung was intubated with 8.0 ID polyvinylchloride endotracheal tube. Cuff was filled with 8ml of saline or saline and viscous lidocaine mixture with 2:1 or 4:1 ratio. Positive pressure ventilation with air in tidal volume of 500 ml was begun. The laser output was set to 10 watt/sec in the continuous mode with beam diameter of 1 mm. Laser beam was directed perpendicularly at the part of the cuff protruding between endotracheal tube shaft and acrylic trachea, and laser emission was continued until the cuff was perforated or combusted. RESULTS: There was no case of laser-induced fires. After the perforation of cuff, the tidal volume was slowly decreased in 2:1 mixture of saline and viscous lidocaine filled cuff compared to others (P<0.05). CONCLUSION: 2:1 mixture of saline and viscous lidocaine may be used as an efficient inflating material of endotracheal tube cuffs on laser airway surgery.

Differences of Incidence and Severity of Sore Throat and Hoarseness between the Methods of Airway Security / 대한구급학회지

Introduction: The sore throat and hoarseness are common complications during the postoperative period. We investigated differences of incidence and severity of sore throat and hoarseness according to methods of airway security. METHODS: One hundred twelve patients, in ASA physical status class 1~2, were included in this study (58 males and 54 females). They were divided into three groups: group 1 (n=42), intubated with endotracheal tube lubricated with normal saline; group 2 (n=40), intubated with endotracheal tube lubricated with 5% lidocaine ointment; group 3 (n=30), inserted with laryngeal mask airway (LMA) for airway security. RESULTS: The incidence of sore throat and hoarseness were 78.6% and 54.8% in group 1, 35% and 30% in group 2, and 33.3% and 20.0% in group 3. CONCLUSIONS: Both 5% lidocaine-lubricated endotracheal tube and laryngeal mask airway showed tendency of decreased incidence of postoperative sore throat and hoarseness but there are no statistical significance.

Displacement of the Endotracheal Tube is not Related to Its Fixation or Unflxation When the Neck is Extended or Flexed / 대한마취과학회지

BACKGROUND: Endobroncheal intubation or extubation may occur accidentally when the patient's neck is flexed or extended even in the appropriate endotracheal intubation. The purpose of this study is to examine the effect of fixation or unfixation of the endotracheal tube at the teeth level on the displacement of its distal end when the patient's neck is extended or flexed. METHODS: This study was conducted in 37 patients who underwent endotracheal general anesthesia. The patients with the evidence of pathology in head, neck and chest were excluded from the study. Individual patient's displacement in endotracheal tube tip compared unfixed cases with fixed cases when the change of neck position. The moved distance was measured by fiberoptic bronchoscope. The data were statistically analyzed by Student's paired t-test. RESULTS: The endotracheal tube moved away from the carina when the patient's neck was extended, while it moved toward the carina when flexed in all cases. When the patient's neck was extended the average distance displaced 1.2 0.7 cm in fixed cases and 1.1 0.9 cm in unfixed cases. when the neck was flexed, they were 1.2 0.5 cm and 1.0 0.8 cm respectively. There were not statistically significant between the fixed and the unfixed cases. CONCLUSIONS: It is concluded that the displacement of the endotracheal tube is not related to its fixation or unfixation at the teeth level and therefore, unfixation does not provide any benefits in terms of the displacement of the distal end of the tube in adult trachea.

The Effect of Endotracheal Tube Cuff Filled with Lidocaine and Sodium Bicarbonate Mixture on Postoperative Sore Throat and Hoarseness Following General Endotracheal Anesthesia / 대한마취과학회지

BACKGROUND: Postintubational sore throat and hoarseness are usually mild symptoms but they are very common complaints among the patients after endotracheal general anesthesia. In addition, some might have severe discomfort and need invasive procedure to relieve these problems. We tried new method of endotracheal tube cuff filling with local anesthetics to reduce postoperative sore throat and hoarseness and evaluated the results. METHODS: Endotracheal cuff filling was done with air 5 ml in healthy 20 patients (ASA I-II, control group). And in another healthy (ASA I-II) 35 patients, the cuffs were filled with 4% lidocaine 3.5 ml and 8.4% sodium bicarbonate 1.5 ml mixture. After 24 hours following general anesthesia, patients were visited and asked whether there were sore throat or hoarseness, if any, how the degree was. RESULTS: In lidocaine-treated group, the incidence of postintubational sore throat was less compared to control group significantly. There was no difference in incidence of hoarseness between two groups. CONCLUSION: Endotracheal cuff filled with lidocaine and sodium bicarbonate mixture is suggested as an effective protective method that reduces the frequency of postintubational sore throat.

A Case of Endotracheal Tube Injury during Maxillofacial Surgery: Case report / 대한마취과학회지

An endotracheal tube provides patent airway during general anesthesia. We experienced the cutting of an endotracheal tube during surgical procedure. The patient with bimaxillary protrusion was operated for cosmetic bimaxillary surgery. The patient was intubated via nasotracheal route with a reinforced endotracheal tube. During surgical procedure, we found air bubbles from the nostril in which the entotracheal tube was inserted. Several milliliters of air was infused into the pilot balloon to inflate the cuff, but air bubbles was noticed continuously. We exchanged the endotracheal tube using a tube exchanger. The removed endotracheal tube was partially cut at 22cm from the tip, probably due to the air-driven saw.