The Ventilatory Effect of Hybrid Ventilation in Rabbits

PURPOSE: Intratracheal pulmonary ventilation (ITPV) is developed to decrease dead space ventilation. A reverse thrust catheter (RTC) is introduced into an endotracheal tube through an adapter. Bias gas through the RTC exits from the catheter tip. The flow of gas is redirected outward away from the lung. Gas is intermittently introduced into the lung as tidal volume (VT) by an expiratory valve. ITPV can be combined with pressure control mode, resulting in hybrid ventilation (HV). We hypothesized that HV might decrease VT, compared with volume controlled ventilation (VCV) or pressure controlled ventilation (PCV) alone. METHODS: HV was compared with VCV and PCV in 7 tracheostomized rabbits. We aimed at maintaining PaCO2 levels normal as the respiratory rates (RR) were set at 20, 40, 80, and 120/min. Blood pressure and airway pressures were monitored and dead space ratio was calculated. RESULTS: The dead spaces (VD) of VCV are 30+/-4 mL, 18+/-4 mL, 14+/-4 mL, and 12+/-5 mL and the VD of PCV are 24+/-6 mL, 16+/-3 mL, 15+/-4 mL and 12+/-4 mL at the respiratory rates of 20/min, 40/min, 80/min, and 120/min, respectively. The VD of HV are 13+/-6 mL, 9+/-3 mL, 7+/-2 mL, and 5+/-1 mL, respectively. The VT and PIP of HV are significantly lower than those of VCV and PCV at the same RR. CONCLUSION: It can be concluded that HV can be applied to minimize the airway pressures and dead space ventilation of VCV and PCV.

Effects of Sodium Nitroprusside-induced Hypotension under Acute Normovolemic Hemodilution on the Cardiovascular System and Systemic Oxygen Balance in Dogs / 대한마취과학회지

BACKGROUND: To decrease homologuous transfusion and bleeding, Acute Normovolemic Hemodilution (ANH) may be combined with induced hypotension. Tissue oxygen balance may be in danger because of decreased tissue perfusion pressure by induced hypotension and reduced arterial oxygen content by ANH. Thus it is necessary to evaluate effects of induced hypotension combined with ANH on hemodynamics and systemic oxygen balance. METHODS: In 6 mongrel dogs anesthetized with N2O-O2-enflurane and paralyzed with vecuronium, ANH was performed up to half of initial level of hemoglobin with isovolemic pentastarch infusion, and then mean arterial pressure (MAP) was lowered by 30% of the initial value by intravenous administration of Sodium Nitroprusside (SNP). Various hemodynamic parameters were measured before and after ANH and 15, 30, 45 and 60 minutes after induction of hypotension and 15 minutes after the end of hypotension. RESULTS: Heart rate was not changed significantly throughout the study. Central venous pressure increased significantly after ANH but decreased to the initial value after induced hypotension. Systemic vascular resistance showed significant decrease after ANH, more significant decrease after induced hypotension and slight increase after discontinuation of SNP. Cardiac output increased markedly by ANH and maintained during induced hypotension. Oxygen flux decreased significantly after ANH but slightly increased after induced hypotension. Oxygen consumption and Oxygen extraction ratio were maintained throughout the study. There were no acidemia and hypoxemia throughout the study. CONCLUSION: The combined use of ANH and induced hypotension with SNP is safe in the aspect of cardiovascular system and systemic oxygen balance.

An Analysis of Blood Transfusion Practice in Total Knee Arthroplasty / 대한마취과학회지

BACKGROUND: Almost all of the blood loss occurring postoperatively in total knee arthroplasty (TKA) is due to the use of an intraoperative tourniquet in all cases. So we tried having blood transfusions done, not by anesthesiologists intraoperatively but by orthopedic surgeons postoperatively. The purpose of this study is to analyze postoperative blood loss and transfusion practice in TKAs. METHODS: We analyzed retrospectively the medical records of 64 TKAs in 40 patients between March, 1997 and February, 1999. RESULTS: Six male and fifty-eight female patients were enrolled. Their mean preoperative, immediate postoperative, and post-transfusion hematocrit were 37.1+/- 3.4, 34.4+/- 3.3, and 34.4+/-3.9, respectively. The preoperative and post-transfusion hematocrit were measured in all cases, but immediate postoperative hematocrit was measured in only 21 cases, and the hematocrit of 17 among the 21 cases was over 32 percent. Drainage amount, for the 1st postoperative day were 843 328 ml, and the total drainage amount was 993+/-362 ml. The blood transfusion amount was 2.6+/-0.9 units. There were no statistically significant differences in preoperative hematocrit, immediate postoperative hematocrit, postoperative drainage amount and postoperative transfusion amount between the general and regional anesthetic group; Preoperative hematocrit did not statistically affect the postoperative transfusion amount, but the postoperative drainage amount was statistically associated with an increased postoperative transfusion amount. CONCLUSIONS: Based on these results, it was concluded that postoperative blood transfusion in TKA was to be done on the basis of clinical impressions of orthopedic surgeons in which postoperative drainage amount was the most important consideration. Therefore, postoperative transfusion should be based on appropriate transfusion guidelines and a careful clinical examination of the patient.

A Comparison of the Effects of Ondansetron and Granisetron on the Prevention of Postoperative Nausea and Vomiting after Gynecologic Surgery / 대한마취과학회지

BACKGROUND: The purpose of this study was to compare the effects of ondansetron and granisetron on the prevention of postoperative nausea and vomiting (PONV) in gynecologic patients. METHODS: In a randomized placebo-controlled study, 200 gynecologic patients were divided into 5 groups. Each patient received one of 5 medications: placebo (saline 3 ml), ondansetron 4 mg (O4), ondansetron 8 mg (O8), granisetron 1.5 mg (G1.5) and granisetron 3 mg (G3). They were administered intravenously immediately before the induction of anesthesia. A standardized inhalation anesthesia and a postoperative intravenous patient-controlled analgesia were applied. Twenty four hours after anesthesia, the incidence and severity of PONV and other adverse effects were assessed. RESULTS: The incidence of PONV was 88%, 83%, 75%, 70% and 60% in the placebo, O4, O8, G1.5 and G3 groups, respectively, which showed significantly lower value in the G3 group than in the placebo and O4 groups (P< 0.05). The severity of PONV was also significantly lower in the G3 group than in the placebo group (P < 0.05). CONCLUSIONS: In this study, granisetron 3 mg showed a better prophylactic effect in the mitigation of PONV in gynecologic patients then a placebo or ondansetron 4 mg.

Clinical Study on Fiberoptic Awake Intubation and Self Pronation in Cervical Spine Disease Patients / 대한마취과학회지

In cervical spine disease patients, the authors performed awake intubation with a flexible fiberscope under local anesthetic preparation to avoid insult to the cervical spine during intubation, and had patients self pronate for positioning to prevent possible complications durings the turning from cart to operating table. We performed this method in 25patients(age15-68 years,19male female6). For oral anesthesia we used 15-20cc of 4% lidocaine in a divided dose. We injected 2 cc of 2% lidocaine for each superior laryngeal nerve block and injected 4-6 cc of 2 to 4% lidocaine through the cricothyroid membrane for transtracheal nerve block with a 22-gauge intravenous catheter. It took 5-10 minutes in 23 patients and over 10 minutes in 2 patients for local anesthetic preparation. It took less than 1 minute in 15 patients, 1-4 minutes in 6 patients and more than 4 minutes in 4 patients for fiberoptic awake intubation. We observed vocal cord movement in 6 patients and blood clot in the trachea in 7 patients. Seventeen patients did pronate without help, 5 patients needed some help and 3 patients needed full support. Among the 3 patients who needed full support, 2 patients were in a halo traction state and one was in deep sedation. Ten patients complained of pain or discomfort during intubation. This complaint may be related which the time taken for intubation and inadequate local anesthesia. There were no complications related to positioning. We concluded that fiberoptic awake intubation and self pronation for positioning is a safe and useful method for anesthetic mnagement in cervical spine disease patients.