In the beginning of anesthetic training, one of the clinical practices that anesthetists have to learn is manually controlled ventilator techniques. The popularity of manually controlled ventilatory techniques has been gradually decreased with increased use for anesthetic ventilators. However it is important and basic for the anesthetists to master manually controlled ventilator techniques skillfully. Recently, we analyzed the arterial blood gas in 30 cases before and during general anesthesia, and studied the effects of the manually controlled ventilation on the pulmonary gas exchange. The results were as follow; 1) Mean value of PaCO₂ during the manually controlled ventilation, 29.9±2.0 mmHg was decreased statistically comparing with that of PaCO₂ before the anesthesia, 39.8±2.8 mmHg. 2) Mean values of pH and HCO₃⁻ during the manually controlled ventilation were 7.48±0.03, 22.2±2.4 mEq/1, respectively and values before the anesthesia were 7.41±0.02, 25.2±1.8 mEq/1, respectively. 3) Mean value of PaO₂ and O₂ saturation during the manually controlled ventilation were 270.0±28.8 mmHg, 99.6±0.2%, respectively and values before the anesthesia were 92.5±4.0 mmHg, 96.9±1.0%, respectively. These results indicates that manually controlled ventilation at our department of anesthesiology produced mild hyperventilatory state. However these were no significant changes in cerebral blood flow and other biochemical parameters.
Anesthesia ; Anesthesia, General* ; Anesthesiology ; Cerebrovascular Circulation ; Hydrogen-Ion Concentration ; Pulmonary Gas Exchange ; Ventilation* ; Ventilators, Mechanical

Two case reports of emergent anesthesia of critical tracheal stenosis are presented. The use of extracorporeal circulation may be a lifesaving method for these patients. Two patients both with severe lower tracheal stenosis were admitted with severe inspiratory dyspnea. The first patient had a tracheal tube inserted above the stenosis in the operating room, but ventilation was unsatisfactory, high airway pressure and severe hypercarbia developed, therefore extracorporeal circulation was immediately initiated. For the second patient, we established femoral-femoral cardiopulmonary bypass prior to induction of anaesthesia, and intubated above the tracheal tumor orally under general anesthesia, then adjusted the endotracheal tube to appropriate depth after the tumor had been resected. The patient was gradually weaned from cardiopulmonary bypass. The two patients all recovered very well after surgery. Surgery is lifesaving for patients with critical tracheal stenosis, but how to ensure effective gas exchange is crucial to the anesthetic management. Extracorporeal circulation by the femoral artery and femoral vein cannulation can gain good gas exchange even if the trachea is totally obstructed. Therefore, before the induction of anesthesia, we should assess the site and degree of obstruction carefully and set up cardiopulmonary bypass to avoid exposing the patient to unexpected risks and the anesthesiologist to unexpected challenges.
Adult ; Anesthesia, General ; methods ; Emergencies ; Extracorporeal Circulation ; Humans ; Male ; Pulmonary Gas Exchange ; Tracheal Stenosis ; surgery

Traditionally, adequate tidal volume is considered to be a necessary condition to support respiratory patient breathing. But the high frequency ventilation (HFV) with a small tidal volume can still support the respiratory patient breathing well. In order to further explore the mechanisms of HFV, the pendelluft ventilation between left and right lungs was proposed in this paper. And a test platform by using two fresh sheep lungs was developed for investigating the pendelluft ventilation between the left and right lungs. Furthermore, considering the viscous resistance ( ), inertance ( ) and lung compliance ( ) in the lung, a second-order lung ventilation model was designed to inspect and evaluate the pendelluft ventilation between left lung and right lungs. On referring to both results of experiments in practice and simulation in MATLAB Simulink, between the left and right lungs, the phase difference in their airflow happens during HFV at some frequencies. And the pendelluft ventilation between the left and right lungs is resulted by the phase difference, even if the total airflow entering a whole lung is 0. Under HFV, the pendelluft ventilation between left and right lungs will benefit the lungs being more adequately ventilated, and will be improve the utilization rate of oxygen in the lungs.
Animals ; High-Frequency Ventilation ; Humans ; Lung ; physiology ; Pulmonary Gas Exchange ; Respiration, Artificial ; Sheep ; Tidal Volume

OBJECTIVETo evaluate the effects of continuous blood purification on the hemodynamics and oxygenation in patients with acute respiratory distress syndrome (ARDS).

METHODSTwenty-one patients with ARDS were treated with continuous veno-venous hemofiltration (CVVH) combined with plasma exchange. Hemodynamics and oxygenation were measured or calculated at scheduled intervals using Swan-Ganz catheters.

RESULTSThe mean arterial pressure, partial pressure of arterial oxygen, oxygen delivery, oxygen consumption increased, heart rate, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, blood lactate concentration all decreased significantly after the treatment, and the oxygen extraction ratio underwent no obvious changes.

CONCLUSIONSContinuous blood purification can increase blood and oxygen supply but has no significant effects on oxygen extraction ratio in ARDS patients.

Adult ; Female ; Hemodynamics ; Hemofiltration ; methods ; Humans ; Male ; Middle Aged ; Oxygen ; blood ; Oxygen Consumption ; physiology ; Partial Pressure ; Plasma Exchange ; methods ; Pulmonary Gas Exchange ; Respiratory Distress Syndrome, Adult ; therapy

The effect of sodium nitroprusside(SNP) on arterial oxygen tension in 20 neurosurgical patients with normal lung function was studied under general anesthesia. Blood gas, heart rate, mean arterial pressure and central venous pressure were measured before, during and after SNP infusion. The results were as follows:1) Arterial oxygen tension significantly decreased from 177+/-40.6 mmHg before SNP to 138+/-50.1 mmHg during SNP(p<0.005), and increased again to 168+/-44.4 mmHg after SNP. 2) Mixed venous oxygen tension decreased 47+/-8.2 mmHg to 40+/-7.3 mmHg(p<0.005), and increased again to 44+/-10.3 mmHg. 3) Heart rate significantly increased from 92+/-24.6 beats/min to 118+/-27.4 beats/min(p<0.005), and decreased again to 94+/-18.6 beats/min. The above findings have shown a marked reduction in PaO2 when SNP was administered during general anesthesia. After SNP, PaO2, returned to the previous values. It is suggested that the reduction in PaO2, is the result of an increased scatter of ventilation/perfusion relationships in the lung and inhibition of hypoxic pulmonary vasoconstriction by SNP. These results provide evidence that SNP induced hypotension may cause significant impairment in pulmonary gas exchange in patients with normal lung function.
Anesthesia, General ; Arterial Pressure ; Central Venous Pressure ; Heart Rate ; Humans ; Hypotension* ; Lung ; Nitroprusside* ; Oxygen* ; Pulmonary Gas Exchange ; Sodium* ; Vasoconstriction

BACKGROUND: Introduction of a pneumoperitoneum using CO2 is accompanied by significant alterations in respiratory function and pulmonary gas exchange during laparoscopic cholecystectomy. Previous studies have shown differing results concerning pulmonary gas exchange: a significant decrease of PaO2 was induced with isoflurane. In contrast, no significant changes were observed with propofol. The purpose of the present study was to compare the effects of propofol vs isoflurane on pulmonary gas exchange during general anesthesia for laparoscopic cholecystectomy. METHODS: Forty patients were divided randomly between isoflurane and propofol groups. After induction of anesthesia, ventilation was controlled and intra-abdominal pressure was maintained automatically at 12 mmHg by a CO2 insufflator. After the measuring of baseline values of blood pressure, heart rate, PaO2, PaCO2 and PetCO2 before CO2 insufflation, measurements were also made immediately, 30min after CO2 insufflation and 5 min after CO2 exsufflation. RESULTS: In the isoflurane group, PaCO2, PetCO2, PaO2, and P(a-et)CO2 changed significantly 30 min after CO2 insufflation and 5 min after CO2 exsufflation (P < 0.05). In the propofol group, PaCO2 and PetCO2 increased significantly 30 min after CO2 insufflation and 5 min after CO2 exsufflation (P < 0.05), but PaO2 and P(a-et)CO2 remained constant. When the two groups were compared, there were significant differences in PaO2, PaCO2, PetCO2 and P(a-et)CO2 at 30min after CO2 insufflation and 5 min after CO2 exsufflation (P < 0.05). CONCLUSIONS: These results indicate that during laparoscopic cholecystectomy the PaO2 was significantly lower and PaCO2 and P(a-et)CO2 were significantly higher in the isoflurane group compared with the propofol group.
Anesthesia* ; Anesthesia, General ; Blood Pressure ; Cholecystectomy, Laparoscopic* ; Heart Rate ; Humans ; Insufflation ; Isoflurane* ; Pneumoperitoneum ; Propofol* ; Pulmonary Gas Exchange ; Ventilation

In 7 apneic dogs, pulmonary gas exchange was compared between the supine and prone position during constant flow ventilantion (CFV) with room air or 100% oxygen at the different flow rate (5, 10, 15, 20 L/min). CFV was performed through two catheter (I.D. 2.0 mm) inserted into both main stem bronchi. The body position of the dogs was changed alternately and the order of flow rate selection was randomized. After 10 min. of each run of CFV, arterial blood gases were measured and alveolar arterial oxygen partial pressure difference (AaDO2) was calculated. AaDO2 with room air under the prone position was significantly smaller than that under the supine position at the flow rate of 5, 15 and 20 L/min. with increasing flow rate, AaDO2 with room air increased significantly regardless body position. No significant difference of AaDO2 with 100% oxygen were observed between the flow rate. The present study shows that ventilation perfusion (V/Q) mismatching during CFV in apneic dogs improved by changing the supine position to the prone position and deteriorated by increasing flow rates, which fact suggests that the impaired oxygenation during CFV is associated with the changes of the status of ventilation perfusion relationship, airway geometry and relative position of intrathoracic organ.
Animals ; Apnea ; Bronchi ; Catheters ; Dogs* ; Gases ; Oxygen ; Partial Pressure ; Perfusion ; Prone Position ; Pulmonary Gas Exchange ; Supine Position ; Ventilation*

Sodium nitroprusside hart become increasingly popular as a vasodilator due to its high potency, rapid onset and reversibility. However, it has some untoward effects including cyanide toxicity, tachyphylaxis, and rebound phenomenon. Accordingly, several attempts to dimmish such complications have been tried including the use propranolol, a possible direct cardiovascular depressant. Therefore, to determine whether propranolol makes a deleterious contribution to hemodynamic responses and impaired in pulmonary gas exchange during SNP in patients anesthetized with halothane-N2O (FiO2; 0.5), experiments were performed on 25 patients with deliberate hypotension scheduled for elective surgery. Thirteen patients were pretreated with divided doses of propranolo (320mg, b.i.d po) and the other twelve were controls. The results were as follows. 1) Cardiac index was significantly lower in pretreated with propranolol than the untreated control in the hypotensive period (3.45+/-0.16 vs 2.97+/-7.141/min/m2, p<0.05). 2) Heart rate increased by 20% in control group during the hypotensive period, but it remained unaltered in propranolol group at all times. 3) Hypotension induced by SNP, resulted from a marked decrease in systemic vascular resistance in both groups. 4) MPAP, PCWP, CVP, SVR, PVR significantly decreased after SNP infusion in both groups, but , they did not differ significantly between the groups at all times. 5) SNP caused a significant increase in intrapulmonary shunt fraction from 8.26+/-0.51 to 10.11+/-0.92%, but propranolo prevented it. 6) Mixed venous oxygen tension was significantly lower in propranolol group than in untreated control group at all times. 7) Patients who .received propranolo required less SNP than the untreated control. (2.51+/-0.22 vs 5.95+/-0.75 mcg/kg/min, p<0.001) These results indicate that propranolol required does not produce any unfavorable hemodynamic event and, furthermore, prevents impairment of pulmonary gas exchange during SNP induced hypotension in patients anesthetized with halothane and nitrous oxide. Therefore, premfdication with propranolol should be considered for patients who are supposed to receive SNP for deliberate hypotension.
Halothane* ; Heart Rate ; Hemodynamics* ; Humans ; Hypotension* ; Nitroprusside ; Nitrous Oxide* ; Oxygen ; Propranolol* ; Pulmonary Gas Exchange ; Sodium* ; Tachyphylaxis ; Vascular Resistance

Sodium nitroprusside hart become increasingly popular as a vasodilator due to its high potency, rapid onset and reversibility. However, it has some untoward effects including cyanide toxicity, tachyphylaxis, and rebound phenomenon. Accordingly, several attempts to dimmish such complications have been tried including the use propranolol, a possible direct cardiovascular depressant. Therefore, to determine whether propranolol makes a deleterious contribution to hemodynamic responses and impaired in pulmonary gas exchange during SNP in patients anesthetized with halothane-N2O (FiO2; 0.5), experiments were performed on 25 patients with deliberate hypotension scheduled for elective surgery. Thirteen patients were pretreated with divided doses of propranolo (320mg, b.i.d po) and the other twelve were controls. The results were as follows. 1) Cardiac index was significantly lower in pretreated with propranolol than the untreated control in the hypotensive period (3.45+/-0.16 vs 2.97+/-7.141/min/m2, p<0.05). 2) Heart rate increased by 20% in control group during the hypotensive period, but it remained unaltered in propranolol group at all times. 3) Hypotension induced by SNP, resulted from a marked decrease in systemic vascular resistance in both groups. 4) MPAP, PCWP, CVP, SVR, PVR significantly decreased after SNP infusion in both groups, but , they did not differ significantly between the groups at all times. 5) SNP caused a significant increase in intrapulmonary shunt fraction from 8.26+/-0.51 to 10.11+/-0.92%, but propranolo prevented it. 6) Mixed venous oxygen tension was significantly lower in propranolol group than in untreated control group at all times. 7) Patients who .received propranolo required less SNP than the untreated control. (2.51+/-0.22 vs 5.95+/-0.75 mcg/kg/min, p<0.001) These results indicate that propranolol required does not produce any unfavorable hemodynamic event and, furthermore, prevents impairment of pulmonary gas exchange during SNP induced hypotension in patients anesthetized with halothane and nitrous oxide. Therefore, premfdication with propranolol should be considered for patients who are supposed to receive SNP for deliberate hypotension.
Halothane* ; Heart Rate ; Hemodynamics* ; Humans ; Hypotension* ; Nitroprusside ; Nitrous Oxide* ; Oxygen ; Propranolol* ; Pulmonary Gas Exchange ; Sodium* ; Tachyphylaxis ; Vascular Resistance

BACKGROUND: Laparoscopic gynecologic surgery is a standard procedure today for its small skin incision and short hospital admission stay. However pneumoperitoneum (PP) and Trendelenberg position induce adverse effects in hemodynamics and pulmonary gas exchange. The purpose of this study is to evaluate the effects of propofol compared with enflurane for pulmonary gas exchange in the Trendelenberg position and pneumoperitoneum. METHODS: Twenty women were randomly allocated to either the enflurane (n = 10) or propofol (n = 10) with fentanyl-N2O/O2 anesthesia. PaCO2, PaO2, PETCO2 were checked at pre-PP, 10 min after PP, 30 min after PP, and 10 min after CO2 deflation. In addition the Vd/Vt ratio was calculated according to the Bohr equation. Vital sign and peak airway pressure were checked at each stage. RESULTS: PaCO2 and PETCO2 increased and PaO2 decreased significantly during PP in both groups. Vd/Vt increased significantly in the enflurane group at 30 min after PP. Peak airway pressure increased significantly in both groups. Blood preassure and heart rate were not changed significantly. All of the parameters were not significantly different between groups. CONCLSIONS: Propofol compared with enflurane did not show any advantage in gas exchange during gynecologic laparoscopic surgery under Trendelenberg position and PP.
Anesthesia* ; Enflurane* ; Female ; Gynecologic Surgical Procedures ; Heart Rate ; Hemodynamics ; Humans ; Laparoscopy* ; Pneumoperitoneum ; Propofol* ; Pulmonary Gas Exchange ; Skin ; Vital Signs