A tube in the pharynx for emergency ventilation

BACKGROUND: If the endotracheal placement of a nasal advanced tube fails, ventilation via this tube could bridge the time until a fibreoptic bronchoscope is available. This study investigates the efficiency of ventilation via a tube resting with its tip in the pharynx near the glottis. METHODS: In 20 patients respiratory data during ventilation via a pharyngeally placed tube were recorded by means of pulse oximetry, capnometry and side-stream spirometry. Results were compared with those measured previously in the same patients during conventional facemask ventilation. RESULTS: Oxygen saturation and end-tidal carbon dioxide concentration remained unchanged using ventilation via facemask (SO2 98.5 +/- 0.9%, FECO2 4.5 +/- 0.7 vol%) or pharyngeal tube (SO2 98.6 +/- 0.7%, FECO2 4.8 +/- 0.4 vol%). No significant differences were found between the two groups with regard to peak airway pressure, tidal volume leakage, compliance and resistance of the respiratory system. CONCLUSIONS: Our results suggest an effective ventilation and oxygenation via a tube placed with its tip in the pharynx. This technique may be helpful during difficult and prolonged nasal intubation.     

The Melkersson Rosenthal syndrome--a differential diagnosis of facial sarcoidosis

Patients with Turner's syndrome present a multiplicity of cardiovascular and airway abnormalities. We describe a case of Turner's syndrome with pericardial effusion who experienced an inadvertent endobronchial intubation due to displacement of the endotracheal tube immediately after the pericardial drainage. A sudden increase of airway pressure and decrease of oxygen saturation in the presence of breathing sound audible via the chest piece placed on the left hemithorax first misled us to call our attention to sputum impaction. No sputum was obtainable from airway suction. Inadvertent bronchial intubation was highly suspected at the post-anesthesia room when a decrease of right side breathing sound was noted together with a progressive fall of oxygen saturation. Emergent chest x-ray confirmed the diagnosis. It was thought that the mishap took place early in the act of or following the pericardial drainage. Our case serves as evidence once again to emphasize the possibility of endobronchial intubation due to displacement of endotracheal tube during anesthesia and the importance of monitoring to guard against inadvertent bronchial intubation, particularly in patients with associated problems such as Turner's syndrome with huge pericardial effusion.     

支气管阻塞器用于胸腔镜下肺癌术患者单肺通气的效果

Objective: The aim of this study was to observe the effect of endobronchial blocker tube in the pulmonary carcinoma with video-assisted thoracic surgery. Methods: Forty patients of pulmonary carcinoma with video-assisted thoracic surgery were randomly assigned into two groups with twenty cases each : endobronchial blocker tube group (group 1) and double-lumen endobronchial tube group (group 2). After anesthesia was induced, in group 1, single lumen tube was intubated at first, and then endobronchial blocker tube intubated to left or right primary bronchus under the guidance of fiber-optic bronchoscope according to operational necessary, injected 2–4 mL air to blocker balloon and blocker one lateral primary bronchus for one-lung ventilation necessarily; while in group 2, the position of double-lumen endobronchial tube was confirmed with fiber-optic bronchoscope after intubation. Blood samples were collected before anesthesia induction, double lumen ventilation, at the one-lung ventilation of 5 min, 30 min, 60 min, 120 min and 180 min, SBP, DBP, HR, SpO2, partial pressure of end tidal carbon dioxide (PetCO2), pH, PaO2, PaCO2,PaO2/FiO2 were recorded. Results: Forty cases' intubations were all successful. There were no differences in SBP, DBP, HR, SpO2, PetCO2, pH, PaCO2 between two groups in different points (P > 0.05). Paw in group 1 was lower than group 2, PaO2 and PaO2/FiO2 in group 1 was higher than group 2 in the one lung ventilation of 5 min, 30 min, 60 min, 120 min and 180 min. Conclusion: The endobronchial blocker tube can meet the request of video-assisted thoracic surgery, with the special advantages of simple insertion, lower airway and better oxygenation. Endobronchial blocker tube offer a new way for one-lung ventilation in the pulmonary carcinoma with video-assisted thoracic surgery.     

Development, characterization and application of an antibody against 5-fluoro-2''deoxyuridine-5''monophosphate, the active metabolite of 5-fluorouracil

To assess the distribution of ventilation to each lung, we measured ventilation and maximum negative airway pressure during occluded inspiratory effort (Pmax) of the individual lungs in eight male patients immediately before and after right upper lobectomy using a double-lumen endotracheal tube at a constant depth of enflurane anesthesia (end-tidal concentration 1.7%). Compared with the breathing pattern observed immediately before surgery, minute ventilation, Pmax, and respiratory frequency significantly increased immediately after the surgery, whereas tidal volume was unchanged. Bronchospirometry revealed that tidal volumes on the nonoperated side significantly increased after the operation. In contrast, tidal volumes on the operated side significantly decreased after the operation and were associated with significantly smaller Pmax obtained from unilateral airway than those of the nonoperated side postoperatively. These results indicate that there are considerable differences in ventilatory function between the lungs on the operated side and nonoperated side. The lung on the nonoperated side can partially compensate for the impaired ventilatory function on the operated side.     

Women are at greater risk than men for malpositioning of the endotracheal tube after emergent intubation

OBJECTIVES: To investigate the occurrence of endotracheal tube malpositioning after emergent intubation in critically ill adults and to determine the need for a routine postintubation chest radiography to assess endotracheal tube position. DESIGN: Prospective study. SETTING: All adult critical care and acute care units of a 560-bed university teaching hospital. PATIENTS: Study of 297 consecutive intubations (185 intubations in males and 112 intubations in females) in 238 adult patients. METHODS: Emergent endotracheal intubations were performed by resident physicians with supervision from an intensive care unit (ICU) or anesthesia attending physician or an anesthesia resident. After intubation, proper positioning of the endotracheal tube was verified by the intubating physician using clinical criteria, including auscultation of bilateral breath sounds, symmetric chest expansion, and palpation of the endotracheal tube cuff in the suprasternal notch. The endotracheal tube position relative to the lower anterior incisors or alveolar ridge was recorded using the centimeter markings printed on the endotracheal tube. A chest radiograph was obtained after intubation to verify endotracheal tube position. Appropriate endotracheal tube position on chest radiograph was defined as between > 2 and < or = 6 cm above the carina. MEASUREMENTS AND MAIN RESULTS: Of the 297 intubations, 26 were excluded from analysis because a chest radiograph was not obtained or the patient was not of normal stature. For the remaining 271 intubations, 42 (15.5%) endotracheal tubes were inappropriately placed, according to the radiographic assessment. The percentage of malpositioned endotracheal tubes was significantly higher in women than in men (61.9% vs. 38.1%, respectively; chi-square: p < .001). Thirty-three (78.6%) of 42 malpositioned endotracheal tubes were placed < 2 cm from the carina, with the highest occurrence (24/33) of proximal malposition occurring in women. Positioning of endotracheal tubes using the centimeter markings printed on the tube referenced to the lower incisors did not accurately identify malposition as documented by chest radiograph. CONCLUSIONS: Emergent endotracheal intubations result in a significant occurrence of malpositioned endotracheal tubes that are undetected by clinical evaluation. Malpositioning is not detected by routine clinical assessment, but only by chest radiograph. Women are at greater risk than men for endotracheal tube malpositioning after emergent intubation; in women, the endotracheal tube is more likely to be positioned too close to the carina. A chest radiograph for confirmation of endotracheal tube position after emergent intubation should remain the standard of practice.     

Comparison of alveolar ventilation, oxygenation, pressure support, and respiratory system resistance in response to noninvasive versus conventional mechanical ventilation in foals

OBJECTIVE: To compare the efficacy of positive pressure ventilation applied through a mask versus an endotracheal tube, using anesthetized/paralyzed foals as a model for foals with hypoventilation. ANIMALS: Six 1-month-old foals. PROCEDURE: A crossover design was used to compare the physiologic response of foals to 2 ventilatory techniques, noninvasive mask mechanical ventilation (NIMV) versus endotracheal mechanical ventilation (ETMV), during a single period of anesthesia and paralysis. Arterial pH, PaO2, PaCO2, oxygen saturation, end-tidal CO2 tension, airway pressures, total respiratory system resistance, resistance across the upper airways (proximal to the midtracheal region), and positive end-expiratory pressures (PEEP) were measured. Only tidal volume (VT; 10, 12.5, and 15 ml/kg of body weight) or PEEP (7 cm of H2O) varied. RESULTS: Compared with ETMV, use of NIMV at equivalent VT resulted in PaCO2 and pH values that were significantly higher, but PaO2 was only slightly lower. Between the 2 methods, peak airway pressure was similar, but peak expiratory flow was significantly lower and total respiratory resistance higher at each VT for NIMV. Delivery of PEEP (7 cm of H2O) was slightly better for ETMV (7.1 +/- 1.3 cm of H2O) than for NIMV (5.6 +/- 0.6 cm of H2O). CONCLUSION: These data suggest that use of NIMV induces similar physiologic effects as ETMV, but the nasal cavities and mask contribute greater dead space, manifesting in hypercapnia. Increasing the VT used on a per kilogram of body weight basis, or the use of pressure-cycled ventilation might reduce hypercapnia during NIMV. CLINICAL RELEVANCE: Use of NIMV might be applicable in selected foals, such as those with hypoventilation and minimal changes in lung compliance, during weaning from endotracheal mechanical ventilation, or for short-term ventilation in weak foals.     

Tracheal pressure triggering a demand-flow continuous positive airway pressure system decreases patient work of breathing

OBJECTIVES: Triggering a ventilator "ON" at the carinal end of the endotracheal tube decreases imposed work of breathing by bypassing the resistance imposed by the breathing circuit and the endotracheal tube. We compared work of breathing during spontaneous ventilation between three methods of triggering the ventilator "ON": a) conventional pressure triggering from inside the ventilator; b) flow-by triggering; or c) tracheal pressure triggering at the carinal end of the endotracheal tube. We hypothesized that the work of breathing would be substantially decreased with tracheal pressure triggering compared with conventional pressure and flow-by methods in patients receiving continuous positive airway pressure. DESIGN: Clinical, prospective study. SETTING: University teaching hospital. PATIENTS: Fourteen adults diagnosed with acute respiratory failure. INTERVENTIONS: All patients were breathing spontaneously at an FIO2 of 0.30 to 0.40 and received 5 cm H2O of continuous positive airway pressure. Three different methods of triggering the ventilator while set in the continuous positive airway pressure mode were administered in random order. MEASUREMENTS AND MAIN RESULTS: Real-time measurements of esophageal pressure and tidal volume were integrated with a respiratory monitor (CP-100, Bicore, Riverside, CA) that uses the Campbell diagram to calculate total work of breathing. Imposed work of breathing was calculated by integrating tidal volume with the pressure at the carinal end of the endotracheal tube. Physiologic work of breathing was calculated by subtracting imposed work of breathing from the total work of breathing. Breathing frequency, the index of rapid shallow breathing (breathing frequency/tidal volume), peak inspiratory flow rate demand, exhaled minute ventilation, and the duration of respiratory muscle contraction assessed by the ratio of inspiratory time to total cycle time were also measured. Data were analyzed by Friedman's repeated-measures analysis of variance on ranks. Alpha was set at .05 for statistical significance. Imposed work of breathing decreased to approximately zero during tracheal pressure triggering. As a result, total work of breathing decreased by approximately 40% compared with the flow-by and conventional methods. During tracheal pressure triggering only, airway pressure increased above baseline pressure to approximately 11 cm H2O, which resembled pressure-support ventilation. Also, during tracheal pressure triggering, tidal volume and peak inspiratory flow rate were significantly increased, while the pressure-time product and the index of rapid shallow breathing were significantly decreased. Hemodynamic status and oxygen saturation were not clinically affected. CONCLUSIONS: The tracheal pressure triggering of a demand-flow continuous positive airway pressure system creates an effect similar to pressure-support ventilation that significantly decreases imposed work of breathing and, thus, total work of breathing. We recommend moving the triggering site of the ventilator to the carinal end of the endotracheal tube.     

Alterations of normal left ventricular performance by general anesthesia

Serial invasive and noninvasive (systolic time interval) measurements of left ventricular performance were obtained in six healthy volunteers during general anesthesia employing the following sequence: thiopental induction, succinylcholine (prior to endotracheal intubation), and halothane--100 per cent oxygen at 1.25 and 1.75 MAC. Heart rate (HR), mean pulmonary arterial "wedge" pressure (PAW) and mean systemic arterial pressure (MAP) were measured continuously; cardiac index and systolic time intervals (STI's) were measured during each intervention. At both levels of halothane, MAP and stroke work index decreased (both P less than 0.02), while HR and systemic vascular resistance did not change. At 1.25 MAC halothane PAW was unchanged, but at 1.75 MAC PAW increased from 8 +/- 4 (SD) to 11 +/- 5 torr (P less than 0.02). Preload was altered at 1.25 MAC by administration of 600-1,000 ml lactated Ringer's solution; PAW increased from 9 +/- 4 to 17 +/- 3 torr (P less than 0.01). At 1.75 MAC halothane, volume expansion increased PAW in a similar manner, but the resultant ventricular function curve was depressed compared with 1.25 MAC halothane. In additon, at each level of halothane anesthesia, the ventricular function curve was depressed compared with results obtained in awake normal subjects. Afterload was altered at 1.25 MAC halothane by infusion of phenylephrine sufficient to raise MAP by 30 per cent. This intervention resulted in a greater depression of cardiac performance than that observed at 1.75 MAC halothane alone. Although alterations in STI's were directionally similar to changes observed in invasive hemodynamic measurements, STI's were sensitive to acute alternations in loading conditions. It is concluded that the levels of halothane commonly employed for general anesthesia significantly depress left ventricular performance in normal subjects, as evidenced by abnormal responses to alterations in preload and afterload, and that STI's should not be employed for routine measurement of left ventricular performance during anesthesia unless both the afterload and the preload on the myocardium are known.     

Fetal unilateral cleft lip and palate: detection of enzymic anomalies in the amniotic fluid

BACKGROUND: Tracheal intubation frequently results in an increase in respiratory system resistance that can be reversed by inhaled bronchodilators. The authors hypothesized that insertion of a laryngeal mask airway would be less likely to result in reversible bronchoconstriction than would insertion of an endotracheal tube. METHODS: Fifty-two (45 men, 7 women) patients were randomized to receive a 7.5-mm (women) or 8-mm (men) endotracheal tube or a No. 4 (women) or No. 5 (men) laryngeal mask airway. Anesthesia was induced with 2 microg/kg fentanyl and 5 mg/kg thiopental, and airway placement was facilitated with 1 mg/kg succinylcholine. When a seal to more than 20 cm water was verified, respiratory system resistance was measured immediately after airway placement. Inhalation anesthesia was begun with isoflurane to achieve an end-tidal concentration of 1% for 10 min. Respiratory system resistance was measured again during identical conditions. RESULTS: Among patients receiving laryngeal mask airways, the initial respiratory system resistance was significantly less than among patients with endotracheal tubes (9.2+/-3.3 cm water x 1(-1) x s(-1) [mean +/- SD] compared with 13.4+/-9.6 cm water x 1(-1) x s(-1); P < 0.05). After 10 min of isoflurane, the resistance decreased to 8.6+/-3.6 cm water x 1(-1) x s(-1) in the endotracheal tube group but remained unchanged at 9.1+/-3.3 cm water x 1(-1) x s(-1) in the laryngeal mask airway group. The decrease in respiratory system resistance in the endotracheal tube group of 4.7+/-7 cm water x 1(-1) x s(-1) was highly significant compared with the lack of change in the laryngeal mask airway group (P < 0.01). CONCLUSIONS: Resistance decreased rapidly only in patients with endotracheal tubes after they received isoflurane, a potent bronchodilator, suggesting that reversible bronchoconstriction was present in patients with endotracheal tubes but not in those with laryngeal mask airways. A laryngeal mask airway is a better choice of airway to minimize airway reaction.     

Respiratory effects of desflurane anesthesia on spontaneous ventilation in infants and children

Volatile anesthetics depress spontaneous ventilation in a dose-dependent manner with variations in effects among different drugs. The goal of this prospective study was to assess respiratory changes during spontaneous ventilation using desflurane/O2/N2O anesthesia in two groups of children. Both groups were undergoing minor surgery and consisted of children < 2 yr old (Group I) and children > 2 yr old (Group II). They were examined at 0.5, 1, and 1.5 minimum alveolar anesthetic concentration desflurane anesthesia. Induction of anesthesia was performed via a face mask and a mixture of O2/N2O (40:60) with halothane. At lease 20 min after stopping halothane, the respiratory variables were recorded on desflurane anesthesia. Tidal volume and minute ventilation decreased significantly (P <0.05) as desflurane increased from 0.5 to 1.5 MAC in both groups. At 1.5 MAC, the respiratory rate was greater in Group II than in Group I (P <0.05). In both groups, the increase in end-tidal CO2 was significant at 1.5 MAC versus 1 and 0.5 MAC (P <0.05). Apnea, i.e., no respiratory movement for 20 s, occurred at 1.5 MAC in one patient in each group. The respiratory duty cycle did not change in any of the groups. Both indices of paradoxical respiration--amplitude index and delay index--did not change. IMPLICATIONS: Desflurane induces respiratory depression at concentrations higher than 1 minimum alveolar anesthetic concentration mainly due to a decrease in tidal volume. Therefore, desflurane at high concentrations should be used cautiously in infants and children with spontaneous ventilation.     

In vivo selectivity of nonsteroidal anti-inflammatory drugs on COX-1-COX-2 and gastrointestinal ulcers, in rats]

BACKGROUND: General anaesthesia affects lung volume and pulmonary gas exchange. What role is played by mechanical stimulation by the endotracheal tube? METHODS: We investigated the effects of intubation on arterial oxygenation and lung volume in rats. RESULTS: Endotracheal intubation caused an increase in PA-aO2 and volume of trapped gas in the lung. This was accompanied by a reduction in neuropeptides and calcitonin gene-related peptide (CGRP) in trachea, bronchi and lung, and in vasoactive intestinal peptide (VIP) in the trachea. The increase in PA-aO2 and volume of trapped gas due to intubation was not altered in the animals given capsaicin, in which neuropeptide levels were reduced. CONCLUSIONS: These data suggest that the decrease in CGRP and VIP content in the airway tissues may be one of the consequences, but not the cause, of impaired gas exchange by endotracheal intubation. The increase in volume of trapped gas in the lung is apparently not mediated by activation of capsaicin-sensitive sensory nerves.     

Collapse of the nasal endotracheal tube in the nasal cavity

A 27-year-old female with maxillary maldevelopment was admitted for mandibular sagittal splitting osteotomy with mandibular progeny. General anesthesia was induced with 100 mg of propofol and 8 mg of vecuronium. When a soft and preformed 7.0 mm North-Polar-nasotracheal tube (Portex) was inserted into the nasopharynx through the left nasal cavity, it was very difficult to advance beyond the choana. After nasotracheal intubation, the buking became harder than before when she had been ventilated with a face mask. The peak airway pressure had reached higher than 50 cmH2O with ventilation of 500 ml tidal volume. Bronchoscopy revealed that the fiberscope (3.5 mm O.D.) could not go through the choanal stenosis, because it was too narrow. Therefore, she had to be intubated by a spiral tube, 6.0 mm I.D., through the other nasal cavity with assistance of bronchoscopy, instead of the North-Polar-tube. So, we have to pay attention to the possibility of compression and collapse of a soft nasotracheal tube in the nose of the patient with choanal stenosis due to maxillary maldevelopment.     

Effects of endotracheal intubation on normal cough performance

To assess the effects of endotracheal intubation on normal cough function, the tracheas of eight healthy volunteers were intubated with a standard 8.0-mm-I.D. tube. Measurements were made of expiratory flow, transpulmonary pressure, and expired volume during a cycle of three successive bursts of maximum voluntary coughing initiated after inspiration to total lung capacity. Results following intubation were compared with findings with subjects breathing through a 25-mm-I.D. mouthpiece (control). Maximum cough pressures (Pmax) following tracheal intubation were similar to control values, but with the tube in place, airflow began well before Pmax was reached and did not cease fully between cough bursts. Flows at Pmax declined with each successive burst of coughing during both experimental conditions, but with tracheal intubation, the flows were significantly lower than control. Resistance to flow at Pmax increased with each successive cough and increased significantly above control during the third burst of coughing while the subjects' tracheas were intubated. The total volume of the three control coughs was 76 +/- 3 per cent of vital capacity. This was similar following intubation, although cough duration was significantly longer. These findings indicate that tracheal intubation does not impair ability to develop normal cough pressures despite preventing glottic closure. The normal timing of flow and pressure is disrupted such that flow occurs early--as in a forced expiratory maneuver, and the flow is not fully interrupted during the cough sequence. Flows are submaximal as a result of the resistance of the tube and continue to decline as the lung volume decreases and airways are compressed. Because the tube is noncollapsible, high flow rates may be necessary to achieve the linear velocities requireed for normal airway cleansing through the tube. Such flows may be achieved only during the initial cough after full inspiration.     

Glottic positioning of the endotracheal tube tip: a diagnostic dilemma

Distal placement of the endotracheal tube tip in the glottic opening is rarely discussed in most emergency medicine, surgery, and prehospital medicine texts. We report three cases of glottic intubation recognized after the patients were thought to have been successfully intubated. Glottic positioning of the endotracheal tube tip went unrecognized initially because of the absence of air heard over the epigastrium, the presence of bilateral breath sounds, and acceptable readings by both pulse oximetry and capnography. Recognition of this complication is aided by the use of radiographic findings, inappropriate endotracheal tube depth, and the presence of inadequate ventilatory volumes. Potential complications of glottic intubation include dislodgement of the endotracheal tube, kinking of the tube, and inadequate protection of the airway.     

Cardiopulmonary effects of rebreathing and nonrebreathing systems during halothane anesthesia in the cat

Cardiopulmonary variables were measured in 3 groups of halothane-oxygen anesthetized cats. The groups, each containing 6 animals, were treated similarly except for maintenance anesthetic systems, and system variation was the basis for comparison. Groups were maintained, using a pediatric circle CO2 absorption system with an O2 flow of 0.5 L/minute, an Ayre's T-piece system with an O2 flow of 3 L/minute, and an adult circle CO2 absorption system with an O2 flow of 0.5 L/minute. Anesthesia was induced by mask, endotracheal intubation was done, and end-expired halothane was maintained at 1.4%. Measurements of cardiopulmonary variables were reported at 30-minute intervals for 135 minutes, the first measurements being made 15 minutes after induction. Control data were similar for all groups. Measured variables were not statistically or clinically different among groups, and change from control within groups was related to halothane anesthesia. The 3 systems produced similar cardiovascular and respiratory effects. Consequently, none of the systems proved superior to the other 2 on the basis of measured variables. Halothane anesthesia produced cardiopulmonary changes comparable to changes reported in other species anesthetized and maintained by similar techniques.     

Propofol and alfentanil prevent the increase in intraocular pressure caused by succinylcholine and endotracheal intubation during a rapid sequence induction of anesthesia

The increase in intraocular pressure (IOP) associated with succinylcholine (Sch) has made its use in patients with open globe injuries controversial. Studies that have examined techniques to prevent the increase in IOP due to Sch have shown a larger increase in IOP from the stimulus of laryngoscopy and endotracheal intubation. The purpose of our study was to examine whether the combination of propofol and alfentanil would prevent the increase in IOP due to Sch as well as endotracheal intubation during a rapid sequence induction of anesthesia. Sixty patients were randomized to receive either thiopental 5 mg/kg and Sch 1.5 mg/kg (Group I), propofol 2 mg/kg and Sch 1.5 mg/kg (Group II), or propofol 2 mg/kg, alfentanil 40 micrograms/kg, and Sch 1.5 mg/kg (Group III). The IOP was measured continuously from baseline awake (control) values until 15 s after successful intubation. All three groups had a significant decrease in IOP with the induction of anesthesia. Succinylcholine produced a consistent increase in IOP from the postinduction low in Groups I and II, but this increase was not significantly higher than baseline. The postintubation IOPs in Groups I and II were significantly higher than baseline (P < 0.001). During the entire study period, the IOP in Group III never increased above baseline. The IOP in Groups I and II had already begun to decline by 15 s postintubation, suggesting that laryngoscopy and intubation have the greatest effect on increasing IOP. We conclude that the combination of propofol and alfentanil prevents the increase in IOP from Sch as well as the increase associated with endotracheal intubation during a rapid sequence induction of anesthesia.     

Circulatory changes at the time of anesthetic induction and endotracheal intubation--comparison of thiamylal induction group and propofol induction group

We examined the circulatory changes after intravenous thiamylal with additional injection of thiamylal 1 minute before intubation and after propofol at the time of anesthetic induction and endotracheal intubation. Sixty ASA I or II patients were studied after the institutional and informed consents. We compared the following three groups. Group I (n = 20): Anesthesia was induced with thiamylal 5 mg.kg-1 and intubation with the aid of vecuronium 0.1 mg.kg-1. Group II (n = 20): Anesthesia was induced with thiamylal 3 mg.kg-1 and vecuronium 0.1 mg.kg-1. One minute before the intubation, the patients received additional thiamylal 4 mg.kg-1. Group III (n = 20): Anesthesia was induced with propofol 2.5 mg.kg-1 and intubation was performed with the aid of vecuronium 0.1 mg.kg-1. We examined the systolic, diastolic and mean blood pressures, heart rate, and rate pressure product (RPP) in the three groups. The examinations were performed before and after induction, soon after intubation, and every one minute after intubation for 5 minutes. After the endotracheal intubation, the systolic blood pressure and heart rate increased in Group I. But the systolic and diastolic pressures were significantly more stable in Group II and Group III. The change of the RPP was slight and most stable in Group II compared with the other two groups. We conclude that additional injection of thiamylal 4 mg.kg-1 following induction of anesthesia with thyamylal 3 mg.kg-1 1 minute before endotracheal intubation is an effective method for minimizing the increase in blood pressure and circulatory changes at the time of rapid induction of anesthesia and endotracheal intubation.     

Carboxyeosin decreases the rate of decay of the [Ca2+]i transient in uterine smooth muscle cells isolated from pregnant rats

We assessed whether using the tracheal diameter to predict the correct size of the left double-lumen endobronchial tube (DLT) could be used for our generally smaller sized Asian patients. Sixty-six consecutive adult patients under anesthesia for elective surgery requiring the use of a DLT were studied. The size of the left-sided DLT used was based on the width of patients' trachea measured from the preoperative posterior-anterior chest radiograph. The placement of the DLT was standardized and confirmed with fiberoptic bronchoscopy. The correct size of the DLT was the largest size tube inserted into the left bronchus with a small air leak detectable when the endobronchial cuff was deflated but not exceeding the recommended resting volume when inflated for lung isolation. Using this method of choosing our DLT, we found that an oversized DLT was often chosen especially among our female Asian patients. The overall positive predictive values for the male and female patients were 77.3% and 45.5%, respectively. We postulate that this could be due to our criteria for correct DLT size or that our local Asian patients, especially the females, were smaller and shorter. IMPLICATIONS: This study assessed whether the correct double-lumen endobronchial tube size could be predicted from tracheal diameter measurements taken from the chest radiograph. We found that this method of choosing the double-lumen endobronchial tubes was not always reliable.     

The effect of magnesium sulphate on hemodynamics and its efficacy in attenuating the response to endotracheal intubation in patients with coronary artery disease

Laryngoscopy and endotracheal intubation may produce adverse hemodynamic effects. Magnesium has direct vasodilating properties on coronary arteries and inhibits catecholamine release, thus attenuating the hemodynamic effects during endotracheal intubation. We studied 36 patients with coronary artery disease (CAD) scheduled for elective coronary artery bypass grafting to evaluate the hemodynamic effects of magnesium and its efficacy in attenuating the response to endotracheal intubation. Patients received either 0.1 mL/kg (50%) magnesium sulfate (50 mg/kg) (Group A, n = 19) or isotonic sodium chloride solution (Group B, n = 17) before the induction of anesthesia and 0.05 mL/kg of isotonic sodium chloride solution (Group A) or lidocaine 2% (1 mg/kg) (Group B) before intubation. The hemodynamic variables were recorded before induction, after the trial drug, after induction, and after endotracheal intubation. Automatic ST segment analysis was performed throughout the study period. Magnesium sulfate administration was associated with increased cardiac index (P < 0.01), a minimal increase in heart rate, and a significant decrease in mean arterial pressure (MAP) and systemic vascular resistance (SVR) (P < 0.001). None of the patients in the magnesium group had significant ST depression compared with three patients in the control group. The magnesium group patients had a significantly lesser increase in MAP (P < 0.05) and SVR (P < 0.01) compared with the control group patients who received lidocaine before endotracheal intubation. Thus, magnesium is an useful adjuvant to attenuate endotracheal intubation response in patients with CAD. IMPLICATIONS: Endotracheal intubation produces adverse hemodynamic effects, which may be more detrimental in patients with coronary artery disease than in healthy patients. The present study shows that magnesium administered before endotracheal intubation can attenuate this response better than lidocaine.     

Intraoperative vascular monitoring of ipsilateral vs. contralateral TRAM flaps

The effects of halothane and isoflurane followed by subsequent administration of vecuronium on the QT interval have been investigated during the induction of anaesthesia. Fifty-eight children, ASA I, without cardiovascular and electrolyte abnormalities and not receiving any medication were studied. Anaesthesia was induced with either halothane (n = 28) or isoflurane (n = 30), and was maintained until the end of the study with end-tidal concentrations of 2.5-3%. Recordings of ECG, heart rate and systolic arterial pressure were obtained at the following times: prior to induction of anaesthesia; 1 and 3 min after stable end-tidal concentrations of the induction agent had been reached; 1 and 3 min following vecuronium administration; at the time of tracheal intubation; 1 and 3 min later. Halothane significantly shortened the QTc interval (P < 0.05); isoflurane prolonged it (P < 0.001). Heart rate decreased significantly after halothane administration (P < 0.01); in contrast, heart rate increased after induction of anaesthesia with isoflurane (P < 0.05), increasing further after laryngoscopy and tracheal intubation (P < 0.001). Systolic arterial pressure decreased significantly (P < 0.001) in both groups after induction of anaesthesia and remained decreased until the end of the study. It is concluded that halothane may be a better choice than isoflurane for children with a long QT interval.