Laryngeal resistance before and after minor surgery: endotracheal tube versus Laryngeal Mask Airway

BACKGROUND: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway trade mark (LMA). METHODS: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs (the LMA group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis. RESULTS: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups. CONCLUSIONS: Postoperative laryngeal resistance increases at least in part because of laryngeal swelling in patients with ETT placement, whereas alteration of laryngeal neural control mechanisms has been also indicated. The use of the LMA trade mark has an advantage over ETT placement in order to avoid postoperative laryngeal swelling.     

Laryngeal Reflex before and after Placement of Airway Interventions: Endotracheal Tube and Laryngeal Mask Airway™

Background: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway(TM).

Methods: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway(TM) groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis.

Results: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway(TM) placement.     

Laryngeal reflex before and after placement of airway interventions: endotracheal tube and laryngeal mask airway

BACKGROUND: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway. METHODS: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis. RESULTS: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway placement. CONCLUSIONS: With either airway intervention, laryngeal defensive reflexes are depressed immediately after surgery even without visible laryngeal swelling. The sensory impairment attributable to the presence of an ETT cannot be the solo factor responsible for the modification of the defensive airway reflexes elicited from the larynx.     

SLIPA~(TM)喉罩与普通喉罩用于全麻气道管理的比较

目的 比较SLIPA~(TM)喉罩(slieamlined pharynx airway liner,SLIPA~(TM))与普通喉罩(1aryngeal mask airway,LMA)用于全麻短小手术气道管理的性能.方法 选择60例ASA Ⅰ或Ⅱ级择期全麻下短小手术的成年患者,随机分为2组,分别建立SLIPA~(TM)通气道(SLIPA~(TM)组)或LMA通气道(LMA组).从通气道的操作、咽密封性、正压通气的维持以及剐作用等方面对通气道的性能进行评估.结果 SLIPA~(TM)与LMA插入操作的成功率和难易程度差异无统计学意义.SLIPA~(TM)组最大密封压(22±5)cm H_2O与LMA组(24±6)cm H_2O差异无统计学意义(P>0.05).通气道插入后SLIPA~(TM)组1例患者(3.3%)、LMA组6例患者(20%)需进一步调整位置方可行间歇正压通气;术中lJMA组5例患者(16.7%)需重新调整方可维持间歇正压通气,SLIPA~(TM)组均顺利完成手术全程间歇正压通气(P<0.05).2种喉罩通气道喉损伤的发生率差异无统计学意义.结论 SLIPA~(TM)喉罩的临床性能与LMA相似,是一种可替代LMA的通气道.SLIPA~(TM)喉罩操作简便,对咽喉损伤较小,维持间歇正压通气较LMA更为稳定.     

Randomized controlled trial comparing the laryngeal tube and the laryngeal mask in pediatric patients

BACKGROUND: The laryngeal tube (LT) is a supraglottic ventilatory device used in adults. However, there is limited information about LT use in pediatric patients. This randomized controlled study compares LT with laryngeal mask (LMA) for airway management during spontaneous or assisted ventilation and during fiberoptic laryngoscopy in children. METHODS: Thirty children under 10-years old, ASA I-II, scheduled for minor general surgery, Mallampati score I-II, fasted and premedicated were included. Patients with upper respiratory infection, craniofacial malformation, intracranial hypertension, emergency surgery were excluded. The primary outcome measure was the proportion of patients in whom effective spontaneous or assisted ventilation [Vt > or = 4 ml.kg(-1), SpO2 > or = 95% with FiO2 0.4, P(E)CO2 < or = 7.2 kPa (55 mmHg)] was achieved after 3 min of LT or LMA cuff inflation. The secondary endpoint was the proportion of patients in whom fiberoptic laryngoscopy resulted in identification of the vocal cords. RESULTS: Eleven children with LMA and two children in LT group had adequate spontaneous or assisted ventilation after initial positioning (P < 0.01). After head extension or device repositioning 15 of 15 patients in LMA group had adequate ventilation compared with 11 of 15 patients in LT group (P < 0.05). The vocal cords could be observed with fiberoptic laryngoscopy in 11 LMA group patients compared with no patients in the LT group (P < 0.001). CONCLUSIONS: The LT is less effective than the LMA to allow adequate spontaneous or assisted ventilation and for fiberoptic evaluation of the airway in children under 10 years old.     

ProSeal喉罩用于体外循环心内直视术患儿气道管理的效果

目的 评价ProSeal喉罩用于体外循环心内直视术患儿气道管理的效果.方法 择期拟行心内直视术患儿76例,年龄3月～8岁,体重3.3～34.5 kg,性别不限,ASA分级Ⅱ级,心功能分级Ⅰ或Ⅱ级,随机分为2组(n=38):气管导管组(T组)和ProSeal喉罩组(P组).麻醉诱导后,T组置入气管导管,P组置入ProSeal喉罩,行机械通气.记录气管导管和喉罩的置入情况、置入时间、最高气道压、术中低氧血症、心动过速、心动过缓、低血压和高血压的发生情况、术后喉头水肿、吞咽困难、呛咳、呼吸困难、声音嘶哑的发生情况.结果 气管导管和ProSeal喉罩全部置入成功.两组术中均未见低氧血症、心动过速、心动过缓、低血压和高血压的发生.与T组比较,P组置入时间缩短,喉头水肿和吞咽困难的发生率降低(P＜0.05),最高气道压、呛咳、呼吸困难和声音嘶哑的发生率差异无统计学意义(P＞0.05).结论ProSeal喉罩置入简单易行,可有效保证通气,对咽喉部刺激较小,用于体外循环心内直视术患儿的气道管理安全可靠.     

喉罩通气全麻联合硬膜外阻滞在腹腔镜胆囊切除术中应用

目的 观察喉罩通气全麻联合硬膜外阻滞在腹腔镜胆囊切除术中的可行性.方法 选择140例择期行腹腔镜胆囊切除的患者,行T8～T9间隙穿刺置管,用1.5%利多卡因行硬膜外阻滞,阻滞平面在T4以下.常规麻醉诱导后,置入4#或5#喉罩,气囊注气20～30 mL,手控通气,观察呼吸道阻力和胸廓起伏状况.结果 本组患者硬膜外穿刺置管均顺利,阻滞效果满意,麻醉平面均在T4以下,插入喉罩时血压、心率无明显变化.气腹后血压均回升(20.6±5.0)mm Hg,心率变化不明显,气道压力均升高(5.7±1.6)cm H2O,手术过程顺利,术后苏醒迅速,在取胆囊时所有患者均恢复自主呼吸.结论 喉罩通气全麻联合硬膜外阻滞,不会造成声带和气道机械损伤,应激反应轻,意识恢复快,是一种安全可行的麻醉方法.     

Airway management in spontaneously breathing anaesthetized children: comparison of the Laryngeal Mask Airway with the cuffed oropharyngeal airway

BACKGROUND: The efficacy and safety of the smallest size of the cuffed oropharyngeal airway (COPA) for school age, spontaneously breathing children was investigated and compared with the Laryngeal Mask Airway (LMA). METHODS: Seventy children of school age (7-16 years) were divided into two groups: the COPA (n=35) and the LMA (n=35). Induction was with propofol i.v. or halothane, nitrous oxide, oxygen and fentanyl. After depression of laryngopharyngeal reflexes, a COPA size 8 cm or an LMA was inserted. Ventilation was manually assisted until spontaneous breathing was established. For maintenance, propofol i.v. and fentanyl or halothane with nitrous oxide were used. Local anaesthesia or peripheral blocks were also used. RESULTS: Both extratracheal airways had a highly successful insertion rate, but more positional manoeuvres to achieve a satisfactory airway were required with the COPA, 28.6% versus LMA 2.9%. The need to change the method of airway management was higher (8.6%) in the COPA group. After induction, the need for assisted ventilation was higher in the LMA group 54.3% versus 20% in the COPA group. Airway reaction to cuff inflation was higher in the LMA group 14.3% versus COPA 5.7%. Problems during surgery were similar, except continuous chin support to establish an effective airway was more frequent (11.4%) in the COPA group. In the postoperative period, blood on the device and incidence of sore throat were detected less in the COPA group. CONCLUSIONS: The COPA is a good extratracheal airway that provides new possibilities for airway management in school age children with an adequate and well sealed airway, during spontaneous breathing or during short-term assisted manual ventilation.     

A comparison between the PLA Cobra and the Laryngeal Mask Airway Unique during spontaneous ventilation: a randomized prospective study

The Laryngeal Mask (LMA) Unique and the Cobra Perilaryngeal Airway (PLA) are single-use supraglottic devices. There are no published studies comparing these devices during spontaneous ventilation. We compared the LMA Unique and the Cobra PLA with respect to 1) ventilatory variables during spontaneous ventilation, 2) time to achieve an effective airway, 3) airway intervention requirements, 4) cuff seal pressures, 5) fiberoptic score, and 6) perioperative adverse events. Eighty adult ASA physical status I-II patients undergoing general anesthesia for minor routine surgery were randomly allocated to LMA Unique or PLA Cobra for airway management. No statistically significant differences were found between the devices with respect to inspiratory tidal volume, expiratory tidal volume, end-tidal CO2 concentration, respiratory rate, number and type of airway interventions required with placement, the fiberoptic score, and the incidence of perioperative adverse events. The oropharyngeal leak (seal) pressure was higher for the CobraPLA (27 +/- 7 versus 21 +/- 4 cm H2O; P < 0.001). The oxygen saturation was higher (98.1% +/- 1% versus 97.3% +/- 2%; P = 0.02) in the LMA group. Time of insertion was shorter for LMA (23.7 +/- 2 s versus 26.6 +/- 7 s; P = 0.02) and insertion difficulty was less for LMA (P = 0.03). As these differences were not judged to be clinically important, both devices appear to be effective in establishing an adequate airway in patients who are spontaneously breathing under general anesthesia.     

Recurrent Laryngeal Nerve Identification and Assessment during Thyroid Surgery: Laryngeal Palpation

Electrical identification and monitoring of the recurrent laryngeal nerve (RLN) has been proposed as an adjunct to standard visual identification of the nerve during thyroid and parathyroid surgery. This study was undertaken to assess laryngeal palpation as an intraoperative technique for identifying and assessing the RLN during surgery and to investigate the relation between laryngeal palpation and associated laryngeal electromyographic (EMG) activity. The postcricoid region of the larynx during surgery was palpated through the posterior hypopharyngeal wall to sense posterior cricoarytenoid muscle contraction in response to ipsilateral RLN stimulation (i.e., the laryngeal twitch response.) Laryngeal palpation was performed in a series of 449 consecutive thyroid and parathyroid surgeries with 586 RLNs at risk. All patients underwent preoperative and postoperative laryngoscopy to assess vocal cord mobility. In a subset of patients, laryngeal palpation and simultaneous laryngeal EMG recordings were compared during intraoperative RLN stimulation. In this series, there was no permanent RLN paralysis. There was one case of temporary RLN paralysis secondary to neural stretch that resolved 6 weeks postoperatively (temporary paralysis rate: 0.2% of patients, 0.2% of nerves at risk). Intraoperative laryngeal palpation of the laryngeal twitch response reliably correlated with normal postoperative vocal cord function. Loss of the laryngeal twitch response occurred in the single case of temporary paralysis in the setting of an anatomically intact nerve. Laryngeal palpation correlated well with simultaneous laryngeal EMG activity. There were no palpation-induced laryngeal injuries or laryngeal edema. There were also no RLN injuries due to repetitive neural stimulation. Intraoperative laryngeal palpation during RLN stimulation is a safe, reliable method for neural monitoring that can assist in RLN identification and assessment during thyroid and parathyroid surgery. Most importantly, it provides important prognostic information regarding ipsilateral vocal cord function at the completion of the initial side of the thyroid or parathyroid surgery. Intraoperative laryngeal palpation allows the surgeon to stage contralateral surgery if RLN damage is diagnosed, thereby avoiding the potential for bilateral vocal cord paralysis. We believe that laryngeal palpation is useful as an adjunct to formal EMG monitoring during thyroid and parathyroid surgery.     

A Prospective Evaluation of Clinical Tests for Placement of Laryngeal Mask Airways

Background: Reliable tests of correct anatomic placement of the laryngeal mask airway (LMA) may enhance safety during use and minimize the need for fiberoptic instrumentation during airway manipulation through the device. This study assessed the correlation between the outcomes of nine clinical tests to place the LMA and the anatomic position of the device as graded on a standard fiberoptic scale.

Methods: During 150 anesthetics, the outcome of nine clinical tests of correct placement was individually scored as satisfactory (positive) or unsatisfactory (negative) for clinical use of the LMA. Anatomic placement was assessed (by fiberoptic evaluation) by an anesthesiologist, who was blinded to the placement of the device, as grade 1, vocal cords not seen; grade 2, cords plus the anterior epiglottis seen; grade 3, cords plus the posterior epiglottis seen; and grade 4, only vocal cords seen. The outcomes of clinical tests were correlated with fiberoptic grade.

Results: Tests that correlated with the fiberoptic grade were the ability to generate an airway pressure of 20 cm water, the ability to ventilate manually, a black line on the LMA in midline, anterior movement of the larynx, outward movement of the LMA on inflation of the cuff, and movements of the reservoir bag with spontaneous breathing. Two tests, ability to generate airway pressure of 20 cm water and ability to ventilate manually, correlated with fiberoptic grades 4 and 3 combined (i.e., the epiglottis was supported by the LMA) and grade 2 (the epiglottis was not supported by the LMA). Tests with poor correlation with fiberoptic grade were the presence of resistance at the end of insertion, inability to advance LMA after inflation of the cuff, and presence of a capnographic trace.     

呼气末二氧化碳分压反映患儿置入喉罩机械通气时动脉血二氧化碳分压的准确性

目的 评价PETCO2反映患儿置入喉罩机械通气时PaCO2的准确性.方法 拟在全身麻醉下行骨科手术患儿52例,ASA分级Ⅰ级,年龄2～9岁,体重10～30 kg.采用分层随机法,将患儿随机分为2组(n=26):喉罩组(LMA组)和气管导管组(ETT组).常规麻醉诱导后行机械通气,待血液动力学稳定后,采集桡动脉血样测定PaCO2,同时记录PETCO2.结果 两组间PETCO2和PaCO2比较差异无统计学意义(P＞0.05);LMA组PETCO2与PaCO2比较差异无统计学意义(P＞0.05).结论 患儿置入喉罩机械通气时,PETCO2可反映PaCO2,用于指导调整机械通气参数.

Abstract：

Objective To investigate the accuracy of end-tidal carbon dioxide (PETCO2) in reflecting arterial carbon dioxide (PaCO2) during mechanical ventilation via laryngeal mask airway (LMA) in children. Methods Fifty-two ASA Ⅰ patients, aged 2-9 yr, weighing 10-30 kg, undergoing orthopaedic surgery under general anesthesia, were randomized into 2 groups (n = 26 each) : LMA group and endotracheal tube (ETT) group. After anesthesia was induced with fentanyl, propofol and succinycholine, LMA or ETT was inserted and the children were mechanically ventilated. After the hemodynamics was stable, arterial blood samples were obtained to detect PaCO2, and PETCO2 was recorded simultaneously. Results There was no significant difference in PaCO2 and PCT CO, between groups LMA and ETT ( P ＞ 0.05) . There was no significant difference between PaCO2 and PETCO2 in LMA group (P ＞ 0.05). Conclusion When mechanical ventilation is performed via LMA in children, PETCO2 can reliably reflect PaCO2 and guide the regulation of ventilatory parameters.     

Continuous monitoring of oesophageal pH during general anaesthesia with laryngeal mask airway in children

We studied the incidence of gastro-oesophageal reflux (GOR) during general anaesthesia with the laryngeal mask airway (LMA) in a paediatric population with two ventilatory regimes: spontaneous breathing and controlled mechanical ventilation (CMV). Thirty children between 6 months and 15 years, ASA I-II, for routine surgery, were randomly assigned in two groups: spontaneous ventilation (n=14), and CMV (n=16). A pH probe was situated in the central third of the oesophagus. Some 66% of the patients breathing spontaneously had GOR episodes vs. 92% of the patients with CMV (P < 0,01). Reflux took place mainly after LMA removal (21% vs. 68%; P < 0,01) and in the Postanaesthetic Care Unit (PACU) (29% vs. 43%; P < 0,05). There was a high incidence of GOR during general anaesthesia and in the PACU in paediatric patients anaesthetized with the LMA. GOR episodes were significantly more evident in the CMV group, mainly after LMA removal, but without clinical significance.     

Recurrent laryngeal nerve palsy after anterior cervical spine surgery: the impact of endotracheal tube cuff deflation, reinflation, and pressure adjustment

BACKGROUND: Vocal fold immobility (paresis or paralysis) from recurrent laryngeal nerve injury remains an important cause of morbidity after anterior cervical spine surgery. A maneuver involving endotracheal tube (ETT) cuff manipulation has been proposed to reduce its incidence. This study is a randomized, prospective, double-blind investigation to test the hypothesis that ETT cuff manipulation reduces the incidence of postoperative vocal fold immobility after anterior cervical spine surgery. METHODS: One hundred patients scheduled to undergo anterior cervical spine surgery were randomly assigned to one of two groups. After inducing general endotracheal anesthesia, patients in the intervention group had their ETT cuff pressures maintained at 20 mmHg or less. After placement of self-retaining retractors, the ETT cuff was deflated for 5 s and then reinflated. Patients in the control group had no further manipulation of their ETT once the cuff was inflated after intubation. Cuff pressures in both groups were recorded before skin incision (baseline) and after placement of self-retaining retractors (peak). Patients' vocal fold motion was evaluated by indirect laryngoscopy performed preoperatively and postoperatively. The examination was videotaped and reviewed by a blinded otolaryngologist. Postoperative vocal fold motion was graded as normal, paretic, or paralyzed. RESULTS: Complete data were available in 94 patients. The incidence of vocal fold paralysis was 3.2% (95% confidence interval, 0.7-9.4%). Cuff manipulation decreased ETT cuff pressure but did not reduce the incidence of vocal fold immobility (15.4% vs. 14.5%). CONCLUSION: Endotracheal tube cuff deflation/reinflation and pressure adjustment do not reduce the incidence of vocal fold immobility in anterior cervical spine surgery.     

LMA-Classic™ and LMA-ProSeal™ are effective alternatives to endotracheal intubation for gynecologic laparoscopy

PURPOSE: To compare the laryngeal mask airways (LMA), LMA-Classic(TM) (LMA-C) and LMA-ProSeal(TM) (PLMA) with the endotracheal tube (ETT) with respect to pulmonary ventilation and gastric distension during gynecologic laparoscopy. METHODS: We stratified 209 women, aged > or = 18 yr, ASA physical status I-III, by body mass index as non-obese (< or = 30 kg x m(-2)) or obese (> 30 kg x m(-2)) and randomized them to LMA-C/PLMA or ETT groups for airway management. Anesthesia was induced with propofol, fentanyl and succinylcholine or rocuronium. In the LMA-C/PLMA group we used a size 4 LMA-C in non-obese patients and size 4 or 5 PLMA in obese patients. In the ETT group we used a cuffed 7.0 mm ETT in all patients. Anesthesia was maintained with isoflurane in nitrous oxide and 30-50% oxygen, fentanyl and neuromuscular blockade with mechanical ventilation (tidal volume 10 mL x kg(-1)). The staff surgeon, blinded to the type of airway, scored stomach size on an ordinal scale 0-10 at initial insertion of the laparoscope and immediately before the conclusion of the surgical procedure. RESULTS: There were no crossovers and no statistically significant differences between LMA-C/PLMA and ETT groups for SpO(2,) P(ET)CO(2) or airway pressure before or during peritoneal insufflation in short (< or = 15 min) or long (> 15 min) periods of peritoneal inflation. Differences between groups with respect to stomach size changes during surgery were not statistically significant. CONCLUSION: A correctly placed LMA-C or PLMA is as effective as an ETT for positive pressure ventilation without clinically important gastric distension in non-obese and obese patients.     

Recurrent Laryngeal Nerve Palsy after Anterior Cervical Spine Surgery: The Impact of Endotracheal Tube Cuff Deflation, Reinflation, and Pressure Adjustment

Background: Vocal fold immobility (paresis or paralysis) from recurrent laryngeal nerve injury remains an important cause of morbidity after anterior cervical spine surgery. A maneuver involving endotracheal tube (ETT) cuff manipulation has been proposed to reduce its incidence. This study is a randomized, prospective, double-blind investigation to test the hypothesis that ETT cuff manipulation reduces the incidence of postoperative vocal fold immobility after anterior cervical spine surgery.

Methods: One hundred patients scheduled to undergo anterior cervical spine surgery were randomly assigned to one of two groups. After inducing general endotracheal anesthesia, patients in the intervention group had their ETT cuff pressures maintained at 20 mmHg or less. After placement of self-retaining retractors, the ETT cuff was deflated for 5 s and then reinflated. Patients in the control group had no further manipulation of their ETT once the cuff was inflated after intubation. Cuff pressures in both groups were recorded before skin incision (baseline) and after placement of self-retaining retractors (peak). Patients' vocal fold motion was evaluated by indirect laryngoscopy performed preoperatively and postoperatively. The examination was videotaped and reviewed by a blinded otolaryngologist. Postoperative vocal fold motion was graded as normal, paretic, or paralyzed.

Results: Complete data were available in 94 patients. The incidence of vocal fold paralysis was 3.2% (95% confidence interval, 0.7-9.4%). Cuff manipulation decreased ETT cuff pressure but did not reduce the incidence of vocal fold immobility (15.4% vs. 14.5%).     

妇科手术患者Guardian喉罩与Supreme喉罩气道管理效果的比较

目的 比较Guardian喉罩与Supreme喉罩用于妇科手术患者气道管理的效果.方法 择期全麻下行妇科手术患者120例,年龄19～80岁,体重50～70kg,ASA分级Ⅰ或Ⅱ级,随机分为2组:Supreme喉罩组(S组,n=59)和Guardian喉罩组(G组,n=61).麻醉诱导后置入4号喉罩,行机械通气.术中监测BP、HR、SpO2、PETCO2和Ppeak.记录喉罩置人情况、置入时间、纤维支气管镜检查分级、气道密封压、正常通气时(VT 8 ml/kg)的气道压、大潮气量(VT20 ml/kg)通气试验时的气道压和漏气的发生情况、术中口咽部漏气的发生情况、拔除喉罩时不良反应和术后咽喉部不良反应的发生情况、麻醉时间、手术时间、喉罩拔除时间和苏醒时间.结果 两组喉罩置入成功率、置入时间、正常通气时的气道压、大潮气量通气试验时的气道压、拔除喉罩时罩体带血和术后咽喉疼痛、声音嘶哑和吞咽困难的发生率、麻醉时间、手术时间、喉罩拔除时间和苏醒时间差异无统计学意义(P＜0.05).两组患者BP、HR、SpO2、Ppeak和PETCO2均在正常范围内.与S组比较,G组纤维支气管镜检查分级和气道密封压升高,大潮气量通气试验时漏气和术中口咽部漏气的发生率降低(P＜0.01).结论 Guardian喉罩和Supreme喉罩置入简单易行,气道密封效果好,可有效保证通气,对咽喉部的刺激小.Guardian喉罩用于妇科手术患者气道管理的效果更好.     

The use of readily available equipment in a simple method for intraoperative monitoring of recurrent laryngeal nerve function during thyroid surgery: initial experience with more than 300 cases

HYPOTHESIS: An inexpensive and widely applicable technique to monitor recurrent laryngeal nerve (RLN) function during thyroid surgery can be safely implemented. DESIGN: Consecutive sample. SETTING: Single-surgeon academic practice. PATIENTS: Three hundred sixty-three consecutive patients undergoing surgery for thyroid disease in the 18 months from November 1, 1999, to May 31, 2001. INTERVENTIONS: Anesthetic management using laryngeal mask airway and spontaneous ventilation, combined with electrical RLN stimulation and fiberoptic video laryngoscopy to confirm vocal cord response. MAIN OUTCOME MEASURES: Vocal cord response to RLN stimulation, intraoperative anatomic findings, postoperative voice quality, and anesthetic complications. RESULTS: We used the laryngeal mask airway-based technique in 327 cases. Visualization of vocal cords was maintained throughout the surgery in 310 cases (95%). In 10 cases (3%), the branch of the RLN carrying vocal cord function could not be identified until electrical testing was performed. A single inadvertent RLN palsy was seen in 1 of the 17 cases in which vocal cord visualization was lost during the procedure (0.03% overall). Upper airway obstruction occurred in 16 (5%) of 327 attempted procedures, requiring tracheal intubation in 3 (1%). No further complications regarding airway management were seen. Pneumothorax was observed in 5 cases (2%), each of which resolved without chest tube placement. CONCLUSIONS: This technique can be applied to thyroid surgery as a safe means of managing the airway. It is associated with an ability to test RLN function at will in more than 95% of cases using readily available equipment.     

Gastric distension and ventilation during laparoscopic cholecystectomy: LMA-classic vs. tracheal intubation

PURPOSE: The standard laryngeal mask airway LMA-Classic was designed as an alternative to the endotracheal tube (ETT) or the face mask for use with either spontaneous or positive pressure ventilation. Positive pressure ventilation may exploit leaks around the LMA cuff, leading to gastric distension and/or inadequate ventilation. We compared gastric distension and ventilation parameters with LMA vs ETT during laparoscopic cholecystectomy. METHODS: One hundred and one, ASA I-II adults scheduled for elective laparoscopic cholecystectomy were randomly assigned to LMA-Classic or ETT. Patients with BMI >30 kg x m(-2), hiatus hernia or gastroesophageal reflux were excluded. Following induction of anesthesia, an in-and-out orogastric tube was passed to decompress the stomach before insertion of the LMA (women size #4, men size #5) or ETT (women 7 mm, men 8 mm). Anesthesia was maintained with isoflurane in nitrous oxide and oxygen (FIO2 0.3-0.5), rocuronium and fentanyl. The surgeon, blinded to the type of airway, scored gastric distention 0-10 at insertion of the laparoscope and immediately before removal at the end of the surgical procedure. RESULTS: Incidence and degree of change in gastric distension were similar in both groups. Ventilation parameters during insufflation (mean +/- SD) for LMA and ETT were: S(P)O2 98 +/- I vs 98 +/- I, P(ET)CO2 38 +/- 4 vs 36 +/- 4 mm Hg and airway pressure 21 +/- 4 vs 23 +/- 3 cm water. CONCLUSION: Positive pressure ventilation with a correctly placed LMA-Classic of appropriate size permits adequate pulmonary ventilation. Gastric distension occurs with equal frequency with either airway device.     

Work of breathing during spontaneous ventilation in anesthetized children: a comparative study among the face mask, laryngeal mask airway and endotracheal tube

Work of breathing (WOB) increases during general anesthesia in adults, but such information has been limited in pediatric patients. We studied WOB in 24 healthy children (mean age 2+/-1.9 yrs), during elective urogenital surgery under 1 minimum alveolar anesthetic concentration halothane-nitrous oxide anesthesia with a caudal block while breathing spontaneously. WOB was measured with an esophageal balloon, miniature flowmeter, and a computerized (Bicore) system. In each patient, WOB was computed under four conditions: a mask without oral airway (-AW), a mask with oral airway (+AW), a laryngeal mask airway (LMA), and an endotracheal tube (ETT). With each apparatus WOB was studied both with continuous positive airway pressure (CPAP) (5-6 cm H(2)O) and without CPAP (or zero end-expiratory pressure [ZEEP]). Under ZEEP, WOB (g x cm/kg) among the four apparatus were (mean +/- SEM): mask (-AW) (64 +/-19.2) > mask (+AW) (44+/-17.2), LMA (42+/-15.6) > ETT (25.4+/- 12.4) (P<0.05). WOB with CPAP significantly (P<0.05) decreased from WOB with ZEEP in three groups (mask [-AW], mask [+AW], and LMA), but not in the ETT group. Tidal volume (both ZEEP and CPAP) and end-tidal PCO(2) (with CPAP only) were significantly (P<0.05) decreased only in the ETT group, whereas no significant difference was found in respiratory rate or minute volume among the four airway apparatus groups, either with or without CPAP. The reduction in WOB, when breathing through ETT was primarily attributable to decreases in tidal volume and volume work. The finding that WOB decreases with CPAP in all groups except for the ETT group suggests that the decrease is a result of improved patency of the upper airway rather than of increases in functional residual capacity and lung compliance.