An evaluation of the Laryngeal Tube during general anesthesia using mechanical ventilation

The Laryngeal Tube is a new supraglottic ventilatory device for airway management. It has been developed to secure a patent airway during either spontaneous or mechanical ventilation. In this study, we sought to determine the effectiveness of the Laryngeal Tube for primary airway management during routine surgery with mechanical ventilation. One-hundred-seventy-five subjects classified as ASA physical status I and II, scheduled for elective surgery, were included in the study. After the induction of general anesthesia and insertion of a Size 4 Laryngeal Tube, measurements of oxygen saturation, end-tidal CO(2) and isoflurane concentration, and breath-by-breath spirometry data were obtained every 5 min throughout surgery. The lungs were ventilated with volume-controlled mechanical ventilation. The number of attempts taken to insert the Laryngeal Tube and the insertion time were recorded. In 96.6% of patients, it was possible to maintain oxygenation, ventilation, and respiratory mechanics by using mechanical ventilation throughout the surgical procedure. The results of this study suggest that the Laryngeal Tube is an effective and safe airway device for airway management in mechanically ventilated patients during elective surgery. IMPLICATIONS: In 96.6% of patients intubated with the Laryngeal Tube, it was possible to maintain oxygenation, ventilation, and respiratory mechanics during mechanical ventilation.     

全麻期间机械通气对患者心功能的影响

目的 评价全麻期间机械通气对患者心功能的影响.方法 选择鼓室成形术ASA Ⅰ或Ⅱ级患者53例,随机分为机械通气组(M组,n=28)和自主呼吸组(S组,n=25).M组麻醉诱导气管插管后行机械通气;S组采取麻醉慢诱导气管插管后保留自主呼吸.术中维持BIS 40～60.于气管插管前、气管插管后1、5、10、20、40、60、90、120及150 min时记录心率(HR)、平均动脉压(MAP)、脉搏血氧饱和度(SpO2)、心输出量(CO)及每搏量(SV);并于气管插管后各时点记录呼气末二氧化碳分压(PETCO2)、潮气量(VT)、呼吸频率(RR)及气道峰压(Ppeak).结果 与S组比较,M组CO、SV、HR及MAP差异无统计学意义(P>0.05),SpO2、Vr及Ppeak较高,RR较慢,PETCO2较低(P<0.05),但均在正常范围.结论 临床麻醉中短时间机械通气对患者的心功能无明显影响.     

Aspects of mechanical ventilation affecting interatrial shunt flow during general anesthesia.

Intraoperative transesophageal echocardiography was used to study the incidence of flow-patent foramen ovale in 33 normal, healthy patients (ASA physical status I) undergoing general anesthesia in the supine position for nonthoracic surgical procedures. Echocardiographic contrast was injected intravenously during mechanical ventilation in the presence of 0, 5, 10, 15, or 19 cm H2O positive end-expiratory pressure (PEEP). A final test was performed during the release of 19 cm H2O PEEP. The presence of a flow-patent foramen ovale was detected when the injected echo targets were observed crossing the interatrial septum from right to left. Most interesting, 3 of 33 patients developed a right-to-left shunt that was first detected with the steady application of 10 (1 patient) or 15 cm H2O PEEP (2 patients). In all three cases, the shunt flow was accentuated on the release of PEEP; however, no additional cases were detected using this respiratory maneuver. These cases represent the first demonstration of right-to-left interatrial shunting evoked as the result of the sustained application of PEEP. This study also revealed a lower than expected incidence of flow-patent foramen ovale (9%) when measured during general anesthesia and positive pressure ventilation with or without PEEP.     

欧普乐喉罩在全麻下气道管理中的应用

目的 探讨欧普乐喉罩(Oro-Pharyngeal airway cap OPLAC)在全麻患者气道管理中的安全性和可行性.方法 60例择期手术患者,ASAⅠ-Ⅱ级.常规麻醉诱导后,根据患者口腔大小选择合适型号欧普乐喉罩,置入喉罩,接吸呼机行正压通气.记录喉罩首次插管成功率,完成操作时间、经喉罩纤维喉镜位置评分,插管即时和插管后3min的平均动脉压(MAP)和心率(HR),气道峰压(Ppeak)和平均气道压(Pmean)及机械通气开始时、30min喉罩密闭压力(Ppeak),机械通气20min、60min、自主呼吸恢复时动脉血气分析,喉罩应用中常见并发症及发生率.结果 60例患者全部成功完成喉罩置入,其中徒手完成操作55例,一次插管成功率75%,二次成功率17%,喉镜辅助置入5例占8%.完成操作时间最短10s,最长130s,平均(33±29)s.机械通气时气道峰压、平均气道压在临床正常数值范围内,其喉罩密闭压力分别为(24±3)cm H2O、(29±3)cm H2O前后比较差异有统计学意义(P＜0.01),机械通气和自主呼吸时的动脉血气分析无异常,总并发症发生率20%,为术中喉罩移位、咽痛和/喉罩带血.结论 OPLAC喉罩是一种安全有效的声门上气道的工具.     

One-lung ventilation of a preterm newborn during esophageal atresia and tracheoesophageal fistula repair

In this paper, we assessed the anesthesia management of a male, a 34-week gestation age newborn, weighing 1500 g, who has esophageal atresia and tracheoesophageal fistula localized just above the carina. Endotracheal intubation and intermittent positive pressure ventilation caused air leakage through the fistula into the stomach, causing abdominal distention. One-lung ventilation by left main bronchus intubation eliminated this problem.     

校正体重设置肥胖患者全身麻醉机械通气潮气量的可行性

目的 评价校正体重设置肥胖患者全身麻醉机械通气潮气量的可行性.方法 肥胖患者60例,拟全麻下择期手术,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其分成3组(n=20):实际体重潮气量组(A组)、理想体重潮气量组(I组)和校正体重潮气量组(C组).麻醉诱导后气管插管,根据相应体重水平,按8 ml/kg设置机械通气初始潮气量,呼吸频率15次/min.于机械通气开始后10min记录气道峰压(Ppeak)、气道平台压(Pp1at)和气道阻力(Raw),机械通气30 min时采集动脉血行血气分析,并记录PaO2、PaCO2及患者需调整潮气量的发生情况.结果 与A组比较,I组和C组PaCO2升高,Ppeak、Pplat、Raw降低(P＜0.01);与I组比较,C组PaCO2降低,Ppeak、Pplat、Raw升高(P＜0.01或0.05);患者需调整潮气量的发生率,C组为0,而A组(95％)和I组(80％)明显升高(P＜0.01).结论 肺功能正常的肥胖患者全身麻醉机械通气时,根据校正体重8 ml/kg设置潮气量是可行的.     

Use of a modified endobronchial tube for mechanical ventilation of patients with bronchopleural fistula.

Mechanical ventilation in patients with bronchopleural fistula after lung resection is a major problem, as it causes increase of the air-leak, complicates the healing process and makes residual lung tissue ventilation difficult. We present two cases in which the use of a modified double lumen endobronchial tube improved ventilation and eliminated the fistula air-leak. We used a right-sided double lumen sher-i-bronch tube (Sheridan Catheter Corp., USA). This method, by blocking the airflow through the fistula, may facilitate the expansion of the residual lung parenchyma. In both the patients treated with this technique, we obtained a good expansion of the residual parenchyma. Despite the procedure, the first patient died of septic shock; in the second patient, we achieved improvement of the respiratory function, the weaning from the mechanical ventilation, and thereafter, the healing of the fistula. The use of a modified double lumen sher-i-bronch tube in mechanically ventilated patients with post-resection bronchopleural fistula allows the anaesthesiologist to suction separately the two lungs and to ventilate adequately the remaining lung tissue, thus obtaining the lung reexpansion and the consequent reduction of the residual pleural space, and facilitating the healing of the fistula.     

Pulmonary perfusion during anesthesia and mechanical ventilation

Cardiac output and the pulmonary perfusion can be affected by anesthesia and by mechanical ventilation. The changes contribute to impeded oxygenation of the blood. The major determinant of perfusion distribution in the lung is the relation between alveolar and pulmonary capillary pressures. Perfusion increases down the lung, due to hydrostatic forces. Since atelectasis is located in dependent lung regions, perfusion of non-ventilated lung parenchyma is common, producing shunt of around 8-10% of cardiac output. In addition, non-gravitational inhomogeneity of perfusion, that can be greater than the gravitational inhomogeneity, adds to impeded oxygenation of blood. Essentially all anaesthetics exert some, although mild, cardiodepressant action with one exception, ketamine. Ketamine may also increase pulmonary artery pressure, whereas other agents have little effect on pulmonary vascular tone. Mechanical ventilation impedes venous return and pushes blood flow downwards to dependent lung regions, and the effect may be striking with higher levels of PEEP. During one-lung anesthesia, there is shunt blood flow both in the non-ventilated and the ventilated lung, and shunt can be much larger in the ventilated lung than thought of. Recruitment manoeuvres shall be directed to the ventilated lung and other physical and pharmacological measures can be taken to manipulate blood flow in one lung anesthesia.     

Nasogastric tube knotting with tracheoesophageal fistula - a rare association

The nasogastric tube is used extensively in medical practice. However, this innocent-looking tube can at times cause unexpected complications especially in patients with preexisting risk factors. A 25-year-old male was referred to our hospital with a blocked and impacted nasogastric tube which had been inserted to maintain his nutritional status after he sustained a caustic injury to the esophagus in an attempted suicide. Esophagoscopy was done, the knotted nasogastric tube was retrieved and a tracheoesophageal fistula was detected at the site of impacted knot. However, the patient succumbed to ARDS and sepsis before definitive surgery could be done. Nasogastric intubation is not a simple procedure as is the general concept and it should not be done in cases of caustic injury to the esophagus because of increased risk of complications in the face of preexisting inflammation. To our knowledge, this is the first case report of its kind in the literature review.     

Esophageal bypass using a gastric tube for a malignant tracheoesophageal/bronchoesophageal fistula: a report of 4 cases

Tracheoesophageal/bronchoesophageal fistulas are often caused by locally advanced esophageal cancer and lung cancer, and result in life-threatening conditions such as severe cough and dyspnea due to pneumonia. We herein report the clinical characteristics of 4 patients with tracheoesophageal/bronchoesophageal fistulas. All patients were men, and ranged in age from 40-69 years. Three patients had esophageal cancer and 1 had lung cancer. All 4 underwent esophageal bypass using a gastric tube with tube drainage of the distal side of the esophagus. Three patients died at 3, 4, and 5 months after surgery. However, these patients were allowed to enjoy food orally up until the last few days of life. One patient who underwent esophageal bypass and chemoradiotherapy has remained well for 5 years without any evidence of recurrence. This bypass procedure is therefore considered to be a feasible treatment choice for patients with tracheoesophageal/bronchoesophageal fistulas.     

QRS-activated ventilation during general anesthesia for extracorporeal shock wave lithotripsy

High frequency ventilation has been claimed to improve the efficiency of extracorporeal shock wave lithotripsy (ESWL) by minimizing the movement of urinary stones during the procedure. A ventilatory mode, QRS-activated ventilation, was developed in which the stones remain motionless during the delivery of shock waves. As the shock wave is triggered to occur approximately 20 milliseconds after the R wave of the QRS complex, the mechanical breath was synchronized to occur approximately 150 ms later. QRS-activated ventilation is used in 16 patients undergoing ESWL under general anesthesia. Tidal volume was set at 3 ml/kg (234 +/- 36 ml; mean +/- SD) at a rate that equaled the heart rate (71 +/- 9 beats/min). The time between the R wave and the initiation of mechanical breath (T1) was 124 +/- 25 ms, time of mechanical breath itself (T2) was 431 +/- 67 ms, and time between end of T2 and next R wave (T3) was 264 +/- 84 ms. End-tidal CO2 measured by the large breath technique was 28.1 +/- 4.8 mmHg. During the clinical use of QRS-activated ventilation and during earlier studies using an EKG simulator and a test lung, the shock wave occurred invariably at end-expiration even at high heart rates.