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氧化亚氮对双腔喉罩套囊内压的影响
Objective To evaluate the effect of nitrous oxide on the intracuff pressure of ProSeal laryngeal mask airway (PLMA) during anesthesia. Methods Thirty patients (ASAⅠ～Ⅱ,24～79yr) were randomized into two groups which inhaled 50% N2O (group N) or oxygen only (group C) during operation. Isoflurane and propofol were used to maintain anesthesia in all patients. The PLMA cuffs were inflated with air to 20mmHg as initial pressure. The intracuff pressure and postoperative airway complication were recorded. Results The intracuff pressure significantly increased and all the cuff pressure exceeded 40mmHg within (46.3±23.6)min and the maximal pressure was 66mmHg in group N. The intracuff pressure remained stable in group A. Deflation volume is more in Group N than in Group C (15.7±5.2ml vs. 9.1±2.5ml; P<0.05). In group N, two patients complained of postoperative sore throat and two patients noticed tongue tip paralysis, while only one 对象与方法 表1 患者一般资料
与同组初始气量比较，P <0.05；与对照组终末气量比较，P <0.05 麻醉期间N2O组喉罩套囊内压持续升高，在(46.3±23.6)min时高达40mmHg以上（图1），最高1例达到66mmHg。对照组喉罩套囊内压保持平稳。麻醉期间两组喉罩套囊内压存在明显差异（P<0.05）。N2O组套囊内终末气量较初始气量明显增加（P<0.05），与对照组比较存在明显差异（P<0.05）（表1）。拔除喉罩后，吸入N2O组和对照组分别有6例(40%)和1例（6%）在套囊内出现少量血迹，组间比较存在明显差异（P<0.05，表2）。表2 两组患者术后情况（例）
与对照组比较，P <0.05 术后24h，N2O组中轻度咽痛和中度咽痛各发生1例，对照组仅有1例发生轻度咽痛（P>0.05）。N2O组有2例病人发生舌尖麻痹，但温觉味觉和运动功能正常，七天后出院时未见明显好转。所有病人术后均无吞咽困难和声音嘶哑等并发症。 讨 论 近年来，双腔喉罩已广泛应用于临床麻醉中。然而，麻醉期间吸入N2O使喉罩套囊内压升高的现象并未受到麻醉医生的足够重视。已有报道显示，双腔喉罩使用后造成咽腔粘膜损伤的比率为3%～28%，术后发生咽痛的比率为2%～49%[7]。多数学者认为术中喉罩套囊内过高压力对咽腔粘膜的压迫是引起术后并发症的原因之一[8]。有研究指出，麻醉期间喉罩套囊内压应维持在60cmH2O(44mmHg）以下，以减少术后咽痛等不良并发症的发生[9]。 本研究结果显示，麻醉期间，对照组病人喉罩套囊内压稳定地保持在初始压力水平，套囊内的气体量也无明显变化（P=0.58）。然而，麻醉期间吸入N2O使双腔喉罩套囊内压持续上升（P<0.05），约1h后高达40mmHg以上，最高1例升至66mmHg。这一结果与van Zundert等[10]在N2O麻醉期间观察普通型喉罩套囊内压从术前45mmHg上升至100mmHg的结果相似。拔管后N2O组喉罩套囊内气体量的明显增多，证明了N2O经弥散作用进入喉罩套囊使套囊内气体量增多，从而导致压力升高。有研究证实，当咽喉部粘膜受压从34cmH2O(25mmHg)上升至80cmH2O(59mmHg)时，粘膜下的血流灌注出现进行性降低，导致咽喉部粘膜发生缺血性损伤[11]。 拔管后喉罩套囊内沾留血迹常被视作咽喉部粘膜损伤的直接证据[7]。本研究发现，N2O组手术结束时拔除喉罩有6例(40%)套囊内有血迹，而对照组仅有1例（6%）(P<0.05)。N2O组和对照组各有2例和1例术后咽痛。使用喉罩发生术后咽痛的原因很复杂，它同时可能与插管方式，插管次数，插管时麻醉深度，病人的性别，手术时间等有关[12]。麻醉期间吸入N2O，由于N2O的弥散作用使喉罩套囊内压过度升高，易对咽喉部粘膜造成损伤，但并不是引起术后咽痛的唯一原因。 本研究中，N2O组还有2例发生舌尖麻痹，随访7天后出院时，麻痹症状还未完全恢复。观察麻痹舌尖处未见明显咬痕或水肿，可排除麻痹因病人术中咬伤所致。Brimacombe[13]也曾报道过一例使用双腔喉罩后发生舌神经损伤造成舌尖麻痹的病例。双腔喉罩使用后发生舌下和喉返神经损伤已有个案报道[14] [15]。神经损伤可能与下列原因有关：①喉罩套囊内压的过度升高（N2O的弥散作用，喉罩偏小使得过度充气）；②插管损伤后引起的局部炎症；③喉罩的错位；④长时间的头颈部体位不当引起神经的牵拉损伤；⑤喉罩套囊表面润滑剂等引起的化学性神经炎[13]。本研究中发生舌尖麻痹的2例病人，术中喉罩套囊内压分别高达64mmHg和66mmHg，喉罩使用时间均超过2h。因此，引起这两例病人舌尖麻痹可能与喉罩套囊内压过高从而压迫舌神经有关。 N2O仍是目前临床麻醉中常用的气体吸入麻醉药，具有性质稳定、不易燃易爆，也不在体内代谢。虽然N2O麻醉效价较低，但镇痛作用强，常与其它麻醉药合用，以减少其它麻醉药用量。在增强镇痛作用的同时，减轻了其它药物对呼吸、心脏的抑制作用。在麻醉期间吸入N2O时，为了防止喉罩套囊内压过度升高可以采取以下措施：①监测套囊内压，间歇性抽出套囊内的部分气体[16]；②向喉罩套囊内预充与吸入气体相同成分的气体[17]；③使用对N2O低通透性材料制作的喉罩套囊（如PVC材料的一次性Soft Seal喉罩）[10]；④向喉罩套囊内预充液态物质（生理盐水或4％利多卡因溶液）。 综上所述，麻醉期间吸入N2O，由于N2O的弥散作用进入双腔喉罩内导致套囊内压过度升高，易对咽喉部粘膜造成损伤，增加了术后咽痛、神经损伤等并发症的发生。 参考文献 1 Burgard G, Mollhoff T, Prien T. The effect of laryngeal mask cuff pressure on postoperative sore throat incidence. J Clin Anesth, 1996, 8:198-201. 2 Umapathv N, Eliathambv TG, Timms MS. Paralysis of the hypoglossal and pharyngeal branches of the vagus nerve after use of a LMA and ETT. Br J Anaesth, 2001, 87:322. 3 Lowinqer D, Benjamin B, Gadd L. Recurrent laryngeal nerve injury caused by a laryngeal mask airway. Anaesth Intensive Care, 1999, 27:202-205. 4 Howath A, Brimacombe J, Keller C. Gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway: A new technique. Anaesth Intensive Care, 2002, 30:624-627. 5 Morris GN, Marjot R. Laryngeal mask airway performance: effect of cuff deflation during anaesthesia. Br J Anaesth, 1996, 76:456-458. 6 Capan LM, Bruce DL, Patel KP, et al. Succinylcholine-induced postoperative sore throat. Anesthesiology, 1983, 59:202-206. 7 Cook TM, Lee G, Nolan JP. The ProSeal laryngeal mask airway: a review of the literature. Can J Anaesth, 2005, 52:739-760. 8 Keller C, Brimacombe J. Mucosal pressure and oropharyngeal leak pressure with the ProSeal versus laryngeal mask airway in anaesthetized paralysed patients. Br J Anaesth, 2000, 85:262-266. 9 Karasawa F, Ohshima T, Takamatsu I, et al. The effect on intracuff pressure of various nitrous oxide concentrations used for inflating an endotracheal tube cuff. Anesth Analg, 2000, 91:708-713. 10 van Zundert AA, Fonck K, Al-Shaikh B, et al. Comparison of cuff pressure changes in LMA Classic and the new Soft Seal laryngeal masks during N2O anesthesia in spontaneous breathing patients. Eur J Anaesthesiol, 2004, 21:547-552. 11 Keller C, Sparr H, Brimacombe J. Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients: comparison of sevoflurane and propofol maintenance techniques. Br J Anaesth, 1998, 80:332-336. 12 Figueredo E, Vivar-Diago M, Munoz-Blanco F. Laryngo-pharyngeal complaints after use of the laryngeal mask airway. Can J Anaesth, 1999, 46:220-225. 13 Brimacombe J, Clarke G, Keller C. Lingual nerve injury associated with the ProSeal laryngeal mask airway: a case report and review of the literature. Br J Anaesth, 2005, 95:420-423. 14 Trumpelmann P, Cook T. Unilateral hypoglossal nerve injury following the use of a ProSeal laryngeal mask. Anaesthesia, 2005, 60:101-102. 15 Kawauchi Y, Nakazawa K, Ishibashi S, et al. Unilateral recurrent laryngeal nerve neuropraxia following placement of a ProSeal laryngeal mask airway in a patient with CREST syndrome. Acta Anaesthesiol Scand, 2005, 49:576-578. 16 Abdelatti MO. A cuff pressure controller for tracheal tubes and laryngeal mask airways. Anaesthesia, 1999, 54:981-986. 17 Brimacombe J, Berry A. Laryngeal mask airway cuff pressure and position: the effect of adding nitrous oxide to the cuff. Anesthesiology, 1994, 80:975-958. |
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