气管插管英文

1、Indications and ContraindicationsAny clinical situation in which a definitive airway is necessary and limited neck motion is permissible is an in dicati on for orotracheal in tubati on. Many of these situati ons, in cludi ng cardiac arrest, airway compromise in in fectio n and trauma, and airway obs

2、tructi on are discussed in detail in Chapter 1 . Most orotracheal intubations are accomplished using a direct laryngoscope. An un stable cervical spine injury is a relative contrain dicati on to direct lary ngoscopy.EquipmentLaryngoscopeFacility in the use of the direct laryngoscope is a prerequisit

3、e for orotracheal intubation. Various adult and pediatric blade sizes are available. There are two basic blade desig ns- curved (MacIntosh) and straight (Miller and Wisconsin). Slight variations in laryngoscopic technique follow from ones choice of blade design, which is often a matter of personal p

4、referenee. The tip of the straight blade goes under the epiglottis and lifts it directly, whereas the curved blade fits into the vallecula and in directly lifts the epiglottis via the hyoepiglottic ligame nt to expose the lary nx. Special blades designed for the anterior larynx include the Siker and

5、 the Belscope (Avulunga Pty Ltd, New South Wales, Australia).Each blade type has adva ntages and disadva ntages. The straight blade is usually a better choice in pediatric patients, in patients with an anterior larynx or a long floppy epiglottis, and in individuals whose larynx is fixed by scar tiss

6、ue. It is less effective, however, in patients with prominent upper teeth, and it is more likely to break teeth. Use of the straight blade is also more often associated with laryngospasm due to its stimulation of the superior laryngeal nerve, which innervates the un dersurface of the epiglottis. A s

7、traight blade may in adverte ntly be adva need into the esophagus and in itially prese nt one with un familiar an atomy un til it is withdraw n. The blade has a light bulb at the tip that may slightly hamper vision. The wider, curved blades are helpful in keeping the tongue retracted from the field

8、of vision, allowing for more room in passing the tube in the orophary nx, and they are gen erally preferred in un complicated adult in tubati ons. Aside from patient considerations, some clinicians prefer the curved blade because they find it requires less forearm stre ngth tha n the straight blade.

9、Tracheal TubesThe sta ndard en dotracheal tube is plastic and measures approximately 30 cm. Tube siz ing is based on internal diameter (ID), measured in millimeters, and ranges from a 2.0 to a 20.0 mm tube, in creas ing in in creme nts of 0.5 mm. The outer tube diameter is 2 and 4 mm larger tha n th

10、e in ternal diameter. Tube size is printed on the tube. There is also a scale, in centimeters, for determining the dista nee along the tube from the tip.Adult men will gen erally accept a 7.5 to 9.0 mm orotracheal tube, whereas wome n can usually be in tubated with a 7.0 to 8.0 mm tube. In most circ

11、umsta nces, tubes smaller tha n these should not be used, especially in patients with chronic obstructive lung disease who may be difficult to wean from the respirator due to excessive airway resista nee from a small tube. However, i n emerge ncy intubations, particularly if a difficult intubation i

12、s anticipated, many clinicians choose a smaller tube and change to a larger tube later if necessary. One exception is in the burn patie nt, in whom one places as large a tube as possible on the in itial attempt because swell ing may prohibit subsequent tube placement. For nasal intubation, a slightl

13、y smaller tube (by 0.5 to 1.0 mm) is chose n.The cuff of a standard tracheal tube is high-volume and low-pressure. A clinical test for determining correct cuff inflation is to slowly inject air until no air leak is audible while the patient is receiving bag-tube ventilation. This usually occurs with

14、 5 to 8 mL of air if the proper-sized tracheal tube has bee n selected. Many cli nicia ns use the tension of the pilot ballo on as a guide to cuff inflation; slight compressibility with gentle external pressure indicates adequate inflation for most clinical situations. For Iong-term use, cuff pressu

15、re should be measured and maintained at 20 to 25 mm Hg. Capillary blood flow is compromised in the tracheal mucosa whe n the cuff pressure exceeds 30 mm Hg. In infants and children, the following formula is a highly accurate method for determining correct tracheal tube size:Tube size = 4 + age (year

16、s)/4For most cli ni cal situati ons, however, using the width of the n ail of the little fin ger as a guide is sufficie ntly accurate and has bee n show n to be more precise tha n fin ger diameter 45911.Correct tube size is especially important in the pediatric population, because most patients youn

17、ger than 8 years are intubated with an uncuffed tube; adequate tube size is necessary to provide a good seal betwee n the tube and the upper trachea and to preve nt aspirati on. A cuffed tube is used in children with decreased lung compliance who may require proIonged mechanical ventilation. In a ch

18、ild, the smallest airway diameter is at the cricoid ring rather than at the vocal cords, as in adults. Hence, a tube may pass the cords but go no farther. Should this occur, the n ext smaller sized tube should be passed after reoxyge natio n.Adult endotracheal tubes will accept a standard adaptor on

19、 which the ventilator tubing will fit. Pediatric tubes require a special adaptor with a distal end small eno ugh to accommodate the small tube size.Preparing for IntubationBefore begi nning in tubati on, a nu mber of issues should be addressed. In chrono logic order, they are (1) confirm thatthe req

20、uired in tubati on equipme nt is available and fun cti oning; (2) positi on the patie nt correctly; (3) assess the patie nt for difficult airway; (4) establish in trave nous (IV) access, time permitt ing; (5) draw up essential drugs, and; (6) attach the necessary monitoring devices. In the haste of

21、the mome nt, it is a com mon error to fail to positi on the patie nt properly or to proceed with the procedure before the proper equipment is assembled and checked. Simple omissions, such as faili ng to restra in the patie nts han ds, removi ng den tures, or misplaci ng the suct ion device, can seri

22、ously hamper the performance of the procedure. A suggested pre-intubation checklist is prese nted in Table 2-2 . In addition to the preparation necessary for optimum patient care, the operator should also mini mize exposure to pote ntially in fectious materials . Gen erally, the operator should be g

23、loved and should wear eye and mouth protect ion to guard aga inst exposure to patie nt secreti ons.The en dotracheal tube cuff should be checked for leaks by in flat ing the ballo on before attempt ing intubation. The tube is prepared for placement by passing a flexible stylet down the tube to in cr

24、ease its stiffness and enhance con trol of the tip of the tube. The stylet should not exte nd bey ond the end of the tube. The tube is the n bent in a gradual curve with a more acute an gli ng in the distal one-third to more easily access the anterior larynx. The tip and cuff of the tube are lubrica

25、ted with viscous lidoca ine or ano ther water-soluble gel.The patie nt should be positi oned to optimally alig n the oral, phary ngeal, and lary ngeal axes . The desired position was aptly described by Magill to make the patient appear to be sniffing the morni ng air, with the head exte nded on the

26、n eck and the n eck slightly flexed relative to the torso. A small towel un der the occiput (to raise it 7 to 10 cm) may facilitate positi oning. Positi oning of the head and n eck is a critical step; non optimal head positi oning may be the sole reas on for some in tubati on failures.The Difficult

27、AirwayThe majority of difficult intubations are predictable. Perhaps the most frequently encountered con diti on associated with a difficult in tubati on is the agitated or combative patie nt. Fortun ately, this condition can be readily eliminated through pharmacologic intervention. The classic para

28、meters that predict a difficult intubation include a history of previous difficult intubation, prominent upper in cisors, limited ability to exte nd at the atla nto-occipital joint, 5 poor visibility of phary ngeal structures whe n the patie nt exte nds the ton gue (Mallampatis classificati on, or t

29、he ton gue/phary ngeal ratio), 6 limited ability to ope n the mouth, 7 a limited direct lary ngoscopic view of the lary ngeal in let, 7 and a short dista nce from the thyroid no tch to the chi n with the n eck in exte nsion . 8 Radiographic in dicators of the ease of in tubati on in clude the man di

30、bular length-to-height ratio 9 and the distance from the spine of the atlas to the occiput. 10 In emerge ncy airway man ageme nt, many of these predictors are not obta in able. An exte nsive history is rarely available, the patients are frequently uncooperative, and the presence of trauma limits mov

31、eme nt of the n eck. Fort un ately, some of the key predictors are appare nt simply by observi ng the exter nal appeara nce of the patie nts head and n eck.Patie nts with n eck tumors, thermal or chemical bur ns, traumatic injuries to the face and an terior n eck, an gioedema and infection of the ph

32、ary ngeal and lary ngeal soft tissues, or previous operati ons in or around the airway suggest a difficult in tubati on because distorted an atomy or secreti ons may compromise visualizati on of the vocal cords. Facial or skull fractures may further limit airway options by precluding nasotracheal in

33、tubation. Patients with ankylosing arthritis or developmental abnormalities, such as a hypoplastic mandible or the large tongue of Downs syn drome, are difficult to in tubate because n eck rigidity and problems of ton gue displaceme nt can obscure visualizati on of the glottis. Besides these obvious

34、 congenital and pathologic conditions, the short, thick neck poses the greatest difficulty for performing orotracheal intubation. In such individuals, the larynx is an atomically higher and more an terior, which makes it harder to visualize the vocal cords. These individuals are easily identified by

35、 observing the head and neck in profile. In such patients, apply laryngeal pressure and consider using the straight blade. Use of other options, including n asotracheal in tubati on, may be required.It should be emphasized that some patie nts, despite no rmal-appeari ng an atomy and the abse nce of

36、a complicati ng history, are un expectedly difficult to in tubate. One must be prepared for this rare but in evitable occurre nce.ProcedureAdults |Direct laryngoscopy.The operator is stati oned at the patie nts head . The patie nt is gen erally sup ine with the head at the level of the operators low

37、er sternum. To maintain the best mechanical advantage, the operator keeps his or her back straight and does not hunch over the patie nt; any bending should occur in the kn ees. The left elbow is kept relatively close to the body and flexed to provide better support .In the severely dyspneic patient

38、who cannot tolerate lying down, direct laryngoscopy can be performed with the patient seated semi-erect and the laryngoscopist on a stepstool behind the patie nt. 11The laryngoscope is grasped in the left hand with the blade directed toward the patient from the hypothenar aspect of the operators han

39、d. The patients lower lip is drawn down with the right thumb, and the tip of the laryngoscope is introduced into the right side of the mouth. The blade is slid along the right side of the tongue, gradually displacing the tongue toward the left as the blade is moved to the cen ter of the mouth. If th

40、e blade is in itially placed in the middle of the ton gue, the tongue will fold over the lateral edge of the blade and obscure the airway. Placing the blade in the middle of the ton gue and failure to move the ton gue to the left are two com mon errors preve nti ng visualization of the vocal cords.A

41、s the blade tip approaches the base of the ton gue, the operator exerts a force along the axis of the laryn goscope han dle, lift ing upward and forward at a 45an gle. The epiglottis should come intoview with this maneuver. It may help to have an assistant retract the cheek laterally to further expo

42、se the laryngeal structures. Do not bend the wrist; bending the wrist can result in dental injury because the teeth may be used as a fulcrum for the blade.The step follow ing visualizati on of the epiglottis depe nds on which lary ngoscope blade is used. With the curved blade, the tip is placed into

43、 the vallecula, the space between the base of the tongue and the epiglottis. Continued anterior elevation of the base of the tongue and the epiglottis will expose the vocal cords. If the blade tip is inserted too deeply into the vallecula, the epiglottis may be pushed down to obscure the glottis. 6

44、When using the straight blade, the tip is inserted under and slightly beyond the epiglottis, directly lifting this structure. The jaw and larynx are literally suspe nded by the blade. If the straight blade is placed too deeply, the en tire lary nx may be elevated anteriorly and out of the field of v

45、ision. Gradual withdrawal of the blade should allow the laryn geal in let to drop dow n into view. If the blade is deep and posterior, the lack of recog ni zable structures in dicates esophageal passage; gradual withdrawal should permit the lary ngeal inlet to come into view.Proper neck positioning

46、and pressure (cephalad, dorsally, and rightward) on the larynx by an assistant will facilitate visualization and intubation of an anterior larynx. If needed, suctioning is performed at this point. If the vocal cords are still not seen, consider using a tracheal tube introducer (Smiths Industries Med

47、ical Systems, Keene, NH). This device, also known as the elastic gum bougie, is a long, semirigid introducer that is placed, using the laryngoscope, through the lary ngeal inlet and into the trachea. 12A The tracheal tube is the n passed over the in troducer and the in troducer is withdraw n. If res

48、ista nee is met i n pass ing the tracheal tube, rotate the tube 90 counterclockwise and advanee the tube.Tube passage.Once the vocal cords have bee n visualized, the final and most importa nt step, tube passage un der direct vision through the vocal cords and into the trachea, is performed. The tube

49、 is held in the operators right hand and introduced from the right side of the patients mouth. The tube is advaneed toward the patients larynx at an angle, not parallel with or down the slot of the laryngoscope blade. This way, the operators view of the larynx is not obstructed by the hand or the tu

50、be until the last possible moment before the tube enters the larynx. The tube should be passed during inspiration, when the vocal cords are maximally open. It enters the trachea when the cuff disappears through the vocal cords. The tube is adva need 3 to 4 cm bey ond this poin t. It is not eno ugh t

51、o see the tube and the cords; the tube must be see n pass ing through the vocal cords to en sure tracheal placeme nt.When the vocal cords are stimulated, lary ngospasm- the persiste nt con tract ion of the adductor muscles of the vocal cords-may preve nt passage of the tube. In adequate an esthesia

52、is often the cause. Pretreatme nt with topical lidoca ine decreases the likelihood of this occurri ng. Two perce nt or 4lidocaine is sprayed directly on the cords. An infrequent but effective route for achieving tracheal anesthesia is via transtracheal puncture, injecting a bolus of 3 to 4 mL of lid

53、ocaine through the cricothyroid membrane. Laryngospasm is usually brief and is often followed by a gasp. The operator should be ready to pass the tube at this mome nt. Occasi on ally, the spasm is proIon ged and n eeds to be broke n with susta ined an terior tract ion applied at the an gles of the m

54、andible-the jaw lift. At no time should the tube be forced, because permanent damage to the vocal cords may result. Con siderati on should be give n to using a smaller tube. ProIon ged, intense spasm may ultimately require muscle relaxation with a paralyzing drug . The pediatric patient is far more

55、prone to lary ngospasm tha n is an adult. 12 In a child, if vocal cord spasm preve nts tube passage, a chest thrust man euver may mome ntarily ope n the passage and permit in tubati on.Positioning and securing the tube.The endotracheal tube should be secured in a position that minimizes both the cha

56、nee of inadvertent endobronchial intubation and the risk of extubation. The tip should lie in the midtrachea with room to accommodate n eck moveme nt. Because tube moveme nt with both n eck flexion and extension averages 2 cm, the desired range of tip location is between 3 and 7 cm above the cari na

57、. 14 On a radiograph, the tip of the tube should ideally be 52 cm above the cariria when the head andneck are in a neutral position. On a portable radiograph, the adult carina overlies the fifth, sixth, or seventh thoracic vertebral body. If the carina is not visible, it can be assumed that the tip

58、of the tube is properly positioned if it is aligned with the T3 or T4 vertebra. In children, the carina is more cephalad tha n in the adult, but it is con siste ntly situated betwee n T3 and T5. In childre n, T1 is used as the reference point for the tip of the en dotracheal tube. 15An estimate of t

59、he proper depth of tube placement can be derived from the following formulas, the len gths represe nti ng the dista nee from the tube tip to the upper in cisors in childre n and from the upper in cisors 18 or the corner of the mouth 19 in adults: Adults: Tracheal tube depth (cm) = 21 cm (wome n)Trac

60、heal tube depth (cm) = 23 cm (me n)In adults, this method has been shown to be more reliable than auscultation in determining the correct depth of placeme nt. 18The cuff is inflated to the point of minimal air leak with positive-pressure ventilation. In an emergency intubation, 10 mL of air is place