WO2009070970A1 - Device comprising endotracheal conduit incorporating bronchial blocker for one-lung ventilation - Google Patents

Abstract

A device (1) for single-lung anesthesia infants or small children comprsing an endotracheal tube (ET) (2), an endobronchial blocker (EB) (8/8') and a port (6) for inflating the EB (8/8') through a tubing (11). The EB (8/8') is incorporated or anchored into a distal portion (4) of the ET (2), whereby preventing retrograde migration of the EB (8/8').

Description

DEVICE COMPRISING ENDOTRACHEAL CONDUIT INCORPORATING BRONCHIAL BLOCKER FOR ONE-LUNG VENTILATION

TECHNICAL BACKGROUD

1. Technical Field

[0001] The invention is in the field of single-lung anesthesia in infants and small children. More specifically, it concerns a device to reduce the common tendency of an endobronchial blocker to retrograde or dislodge into the trachea during one-lung anesthesia in small children, infants, and premature babies.

2. Prior Art

[0002] One-lung anesthesia is required in an increasing variety of pediatric surgeries involving structures in the thorax, especially if minimally invasive techniques are being employed.^1"4 It remains a challenge to provide consistent non- ventilation of one lung with relative ease and reliability in small children, in part, because the choices of lung isolating devices are limited.

[0003] There are currently two popular tubes for one-lung isolation on the market. One is the double lumen tube (DLT) and another is the Univent tube. Other designs exist but are variants of these tubes. The DLT is by far the more popular one. They both have multiple channels, and cannot be made smaller to fit smaller children. The reason is that the channels would get too small and the resistance to airflow too great to be of any use. Certainly passing suction catheters and a pediatric fiberoptic bronchoscope needed for position verification would also be out of the question. That is why the smallest DLT only fits a child of 8-10 years of age and the smallest Univent tube only fits a child of 6-8 years¹. Smaller children will have to use a regular single lumen endotracheal tube (ET) with a separate endobronchial blocker (EB) either through the lumen of the endotracheal tube or outside the lumen, depending on the size the tube, which, of course, is dictated by the size of the child.

[0004] Proper placement of a separate EB is challenging (see below). An alternative way to ventilate only one lung is to deliberate pass the endotracheal tube (ET) distally into the mainstem bronchus of the side to be ventilated. The biggest problem with this approach is that an ET that fits the trachea appropriately may be too big for either of the mainstem bronchi (see Table 1 for diameters of trachea and mainstem bronchi). A small enough tube that fits the mainstem bronchus may have too much leak once the ET is withdrawn back into the trachea for bilateral ventilation. Sometimes, an ET may be too small for the mainstem bronchus, leading to excessive leak and partial ventilation of the opposite supposedly collapsed lung.

[0005] What about a cuffed ET? It would solve the problem of leak around the tube. Unfortunately, the upper lobe of the ventilated side may be blocked by the cuffed ET, thus reducing the volume of ventilated lung to an unacceptably low level. Fig. 1 illustrates the problem of the cuffed ET in the left mainstem bronchus. Since the right mainstem bronchus is even closer to the carina, non-ventilation of the right upper lobe is even a bigger problem than that of the left upper lobe. To avoid this problem, much of the cuff must be in the trachea, thus compromising the seal.

[0006] For the above reasons, a much preferred and popular technique for one-lung isolation in small children is the use of EBs.^1'4 (Fig 2). Depending on the size of the patient and thus the ET, the EB may be placed either intra- or extra-luminal of the ET. For example, a child <10 months of age will likely need an ET with internal diameter <4 mm; an Arndt 5F pediatric EB would need to be extra-luminal of the ET (left panel). (It is important to note that allowance must be made for a pediatric fiberoptic bronchoscope to pass inside the lumen of the ET, i.e., the ET must have a lumen wide enough to accommodate the bronchial blocker catheter and a pediatric fiberoptic bronchoscope simultaneously. If not, the bronchial blocker catheter must be outside the lumen of the ET. Fiberoptic bronchoscopes must be passed within the lumen of an ET; it is impossible to pass a fiberoptic bronchoscope alongside (i.e., extraluminal of) the ET once the ET is in place.)

[0007] Unfortunately, there is a serious potential problem with this approach also. When a balloon-tipped catheter is used to block a mainstem bronchus of a lung, a common problem the anesthesiologist and surgeon face is the tendency of the bronchial balloon to retrograde-dislodge into the trachea^1"3'⁵'⁶ causing loss of lung isolation and leading to partial to total tracheal obstruction (Fig 3). This occurs because the catheter holding the balloon in place is long, thin, flexible, and not strong, and is anchored at the other end outside the patient's mouth.

[0008] If retrograde blocker dislodgement into the trachea is not immediately recognized, hypoxia and even cardiac arrest⁶ could result. At the very least, this leads to loss of lung isolation, interruption of surgery, increased surgical manipulation of and trauma to the supposedly non-ventilated lung, and necessitates the anesthesiologist to reposition the EB, which is always a challenge in the middle of surgery. If the problem persists, the surgeon may have to abandon the minimally invasive approach and convert to an open thoracotomy, thus subjecting the patient to more postoperative pain and a big scar, and the risk of such late complications⁷ as "winged" scapula (24%), marked asymmetry of the thoracic wall (20%), fusion of the ribs (10%), severe scoliosis (8%), and breast maldevelopment (3.3%). Because of their short mainstem bronchi, small children are particularly susceptible to this problem of dislodgement of the EB.

[0009] It is believed that the current technique of anchoring the EB (located at the distal end of a long flexible catheter) at its proximal end is unreliable in preventing retrograde dislodgement of the EB. To date, no solution has ever been proposed to address this problem. The present invention came out of a desire to overcome the above problem.

SUMMARY OF THE INVENTION

[0010] A new device that will overcome the problem of retrograde migration of an endobronchial blocker (EB) during single-lung anesthesia in infants or small children has been designed herein.

[0011] Accordingly, one aspect of the invention is directed to a device for single-lung anesthesia in infants or small children comprising an endotracheal tube (ET) incorporating an endobronchial blocker (EB) at or near a distal end of the ET to prevent retrograde migration of the EB.

[0012] In one embodiment of the invention, the EB is a broad-based EB. In other embodiment of the invention, a base of the EB is incorporated into the ET at or near a distal end of the ET. [0013] Accordingly, the ET and EB as provided herein may form a single unit.

[0014] In a preferred embodiment of the invention, the tip of the ET abuts the carina, securing the EB in the endobronchial position.

[0015] In a preferred embodiment of the invention, the carinal end of the ET is not pointy, and has a somewhat flat to slightly concave-outward shape to improve its contact with the carina and to discourage the device from being inadvertently or too easily pushed into one of the mainstem bronchi.

[0016] In a preferred embodiment of the invention, the end opening of the ET is slanted and faces toward the side opposite to that of the endobronchial blocker 8/8'.

[0017] In one embodiment of the invention, a balloon of the EB is deflated during intubation, and when inflated should have a natural angle (α) of about 30-60° to the long axis of the ET.

[0018] In still a preferred embodiment, the device of the invention is designed for lung isolation in children less than 6-8 years of age. The device as provided herein should come in various sizes to fit children from premature size up to 6-8 years of age, meaning the internal diameter of the endotracheal tube (traditionally this is how one measures endotracheal tubes) portion of the device should be from 2.5 mm to 6.5 mm, with or without a tracheal cuff. The endobronchial balloon blocker must, of course, be in appropriate sizes to fit children of various ages. In other words, the device is suitable for premature children and children from age 0 up to the age of 6-8 years. That said, the same design could be enlarged for use in children above 6-8 years of age and in adults. Even in adults, this design has advantages over the DLT and the Univent tube because it affords one single wide lumen to facilitate ventilation, fiberoptic bronchoscopy, and tracheal toiletry. It may even be cheaper to make. As used herein the terms "newborns" or "premature infants" refer to infants younger than 3 months old, or being 0 to 90 days old.

[0019] Another aspect of the invention is directed to a method of single-lung anesthesia in infants or small children, comprising an intubating device of the present invention in infants and small children, wherein a retrograde migration of an endobronchial blocker comprised in the device does not occur. [0020] Still another aspect of the invention is directed to a method of preparing a device of the invention, comprising incorporating or anchoring an EB near or at a distal end of an ET.

[0021] The ET-EB unit of the present invention is designed such that the problem of retrograde migration of the EB is overcome because the EB is incorporated in the ET; the ET tip, occupying the distal trachea, prevents any retrograde movement of the EB.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 illustrates how a cuffed endotracheal tube could miss the upper lobe of the lung. The margin of safety is worse with right lung ventilation because the right mainstem bronchus is shorter. Figure 1 comes from: Hammer G, Hall S, Davis PJ. Anesthesia for general abdominal, thoracic, urologic, and bariatric surgery. In: Smith's Anesthesia for Infants and Children, 7^th ed. Ed. Motoyama EK, Davis PJ, Mosby 2006, Philadelphia. 685-722.

[0023] Figure 2 shows a conventional technique for lung isolation in small children (<6-8 years of age).

[0024] Figure 3 shows retrograde dislodgement of endobronchial blocker causing loss of lung isolation and airway obstruction.

[0025] Figure 4 schematically shows a new endotracheal tube with a built-in high-volume low-pressure endobronchial blocker in deflated state (left panel) and inflated state (right panel).

[0026] Figure 5 schematically shows a new endotracheal tube with built-in endobronchial blocker in deflated state (left panel) and inflated state (right panel), and with tracheal cuff.

[0027] Figure 6 schematically shows a new endotracheal tube with built-in endobronchial blocker placed to block the right mainstem bronchus. Retrograde dislodgement is prevented because the distal trachea is occupied by the endotracheal tube. As shown in Figure 5, inflated endobronchial blocker is relatively long to block the entire mainstem bronchus, even over-riding the right upper lobe orifice. When the word "Right" (printed on one side of the endotracheal tube) is showing on top, the endobronchial blocker faces the right. When the word "Left" (printed on the opposite side of the tube) is showing on top, the blocker faces the left.

[0028] Figure 7 schematically shows how the device provided herein has been mimicked using existing equipment - anchoring the endobronchial balloon using the Murphy eye of the endotracheal tube. The stem of the balloon catheter is placed either within (panel a) or outside of (panel b and panel c) the endotracheal tube lumen, depending on the size of the endotracheal tube. Note that the tip of a small endotracheal tube has been enlarged (panels b and c) (Drawing not to scale).

[0029] Figure 8 shows that prior to insertion, the co-axially placed blocker was pre-placed within the endotracheal tube with the balloon protruding through the Murphy eye (panel b), or, if the blocker catheter is extra-luminal, with the balloon protruding entirely through the Murphy eye (panel a). Note that for a small endotracheal tube, its tip should be carefully enlarged and trimmed to reduce airflow resistance (panel a).

[0030] Figure 9 shows a presumed ectopic right upper lobe bronchus at the level of the carina (a), the inflated Arndt 5F endobronchial balloon (b), and a schematic (c) of how the entire right lung was blocked with one balloon anchored against the Murphy eye to prevent retrograde dislodgement (drawing not to scale). Without using the catheter through the Murphy eye, it would have been impossible to jam the endobronchial blocker against the left mainstem bronchial orifice and the ectopic right upper lobe orifice simultaneously.

[0031] Figure 10 shows a thoracoscopic view of the nicely collapsed right upper and lower lobes in Case 6.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring to Figures 4 and 5 taken along with Figure 6, there is schematically shown a partially sectioned side view of a preferred illustrative embodiment of device 1 provided herein comprising an endotracheal tube (ET) 2 and an endobronchial blocker (EB) 8/8'. EB 8/8' in structure can be a conventional endobrochial blocker such as an endobronchial balloon. Port 6 at proximal end of tubing 11 can also be comprised in the device 1 to inflate the EB 8/8'. Inflation of EB 8/8' is typically with air but could be with any gas or even a liquid such as water or saline. In one embodiment, the device 1 may further comprise cuff 12 near the distal portion of tubing 13 or being located in the proximal side of the EB 8/8' as showed in Figure 5. A separate injection port 14 at proximal end of tubing 13 is used for inflating cuff 12 (as shown in Figure 5) via the tubing 13.

[0033] The tubing 11 and tubing 13 are preferably fine (with an external diameter in the range of about 0.8-1.2 mm (average about 1 mm)). In a further embodiment, the tubing 11 can be built into or incorporated into the wall of the ET 2. The tubing 13 can also be built into the ET 2. The port 14 should be clearly labeled in color or coded to differ from the port 6 which inflates the EB 8/8'. This port 6 or 14 can be a standard self-sealing port (commonly found in standard endotracheal tubes) injected with a syringe. The port allows injection or extraction of gas or air or fluid when the syringe is connected, but seals once the syringe is disconnected.

[0034] The left panel of Figure 4 or 5 shows the EB in a deflated state 8 and the right panel of Figure 4 or 5 shows the EB in an inflated state 8'. The endobronchial cuff or balloon provided herein can be made from a biocompatible elastomeric material such as, polyurethane, silicone, rubber of silicone plastic, or any other safe synthetic material. The endobronchial balloon 8/8' should be broad based with a wide neck 7 for increased basal support such that the angle α is more or less maintained. The endobronchial balloon and cuff should preferably be a high- volume low-pressure design.

[0035] As used herein, the terms "endobronchial blocker (EB)" "endobronchial balloon" and "bronchial blocker" can be alternately used.

[0036] EB 8/8' is incorporated or securely anchored into ET 2 near its distal portion 4. Thus, the EB 8/8' cannot be detached from the endotracheal tube. A detachable balloon blocker creates the potential for it to be dislodged into the mainstem bronchus, a very dangerous situation.

[0037] As used herein, the term "EB-ET unit" or "ET-EB unit", or "ET-EB device" also refer to the device comprising the EB and ET as provided herein.

[0038] In some embodiments of the invention, ET 2 is designed such that after tracheal intubation, its distal end 5 should abut the carina. The endobronchial balloon blocker 8 is deflated during intubation (left panel of Figure 4). ET 2 can be inserted until resistance is met at an insertion distance commensurate with the size of a patient. The endobronchial balloon 8 is then inflated (right panel of Figure 4) until ventilation of the blocked lung ceases whilst the other lung continues to be ventilated. In a preferred embodiment of the invention, the carinal end of the ET or the distal end 5 is not pointy, and has a somewhat flat to slightly concave-outward shape to improve its contact with the carina and to discourage the device from being inadvertently or too easily pushed into one of the mainstem bronchi. In another preferred embodiment of the invention, an end opening 9 of the ET is slanted and faces toward the side opposite to that of the endobronchial blocker 8/8'.

[0039] Accordingly, provided herein also is a method of single-lung anesthesia in infants or small children, comprising the intubating device provided herein in the infants and small children, wherein a retrograde migration of an endobronchial blocker comprised in the device does not occur. In some embodiments, the method of single-lung anesthesia in infants or small children comprising inserting device 1, the ET-EB unit until the distal end 5 of ET 2 abuts the carina, i.e. resistance is met at an insertion distance commensurate with the size of the infants or small children. The balloon 8 is then inflated until ventilation of a blocked lung ceases whilst the other lung continues to be ventilated. When bilateral ventilation is required, ET 2 is withdrawn slightly and the EB 8/8' completely deflated. Thus, one benefit of the design of the invention is that the anesthesiologist no longer has to place an ET and an EB as two separate items.

[0040] In some embodiments of the invention, the EB 8' when inflated should have a natural angle (α) of about 30-60° to the long axis of ET 2. The problem of retrograde migration of the EB 8/8' is overcome because ET tip or distal end 5, occupying the distal trachea, prevents any retrograde movement of the EB 8/8'. Figures 4, 5 and 6 show the endobronchial balloon 8/8' in the right mainstem bronchus. To place the endobronchial balloon 8/8' in the left mainstem bronchus, ET 2 just needs to be turned with the endobronchial balloon 8/8' facing the left. In an embodiment of the invention, the endobronchial blocker 8/8' should be deflated first, if the rotation must be made with the device already inside the tracheobronchial tree. Thus, ease of placement of the EB is a potential added benefit. Verification of optimum ET placement can be preformed through fiberoptic bronchoscopy, with the view of the mainstem orifice as confirmation. In premature babies, because the internal diameter of ET 2 is too small even for pediatric fiberoptic bronchoscopes, the EB 8/8' should already be in its optimum position once ET 2 is placed with its tip or end 5 abutting the carina, obviating the need for fiberoptic bronchoscopic verification. Accordingly, another advantage of the invention is the reduced need for fiberoptic bronchoscopic verification of endobronchial blocker position because the depth of placement (ET tip abuts carina) is well defined and the endobronchial blocker is fixed near the ET tip. This advantage is particularly important in premature infants and newborns because current pediatric fiberoptic bronchoscopes do not pass through endotracheal tubes with internal diameter 2.5 mm, making verification of endobronchial blocker position using existing equipment and technique impossible. This is a huge advantage of this new invention as fiberoptic bronchoscopic verification is currently always necessary when a conventional endotracheal tube and a separate blocker are placed.

[0041] The dimension of the new ETs main body should be similar to currently available standard ETs. Any ET which size is suitable for the infants or small children younger than 6 years old can be used in the device provided herein, provided that the ET has a similar structure as shown in Figures 4-6. In a preferred embodiment, the internal diameter of ET 2 in the new ET-EB device as provided herein should come in sizes ranging from 2.5 mm to 9 mm in 0.25 mm increments, and with and without a tracheal cuff for maximum flexibility. The thickness of ET 2 is no different from a regular single lumen endotracheal tube. The EB 8/8' should be of high- volume low-pressure design to minimize pressure on the bronchial mucosa. In a preferred embodiment of the invention, the EB 8/8' has a wide neck 7 (Figures 4 and 5) to prevent kinking. Neck 7 could be even wider than depicted in Figures 4-6. For example, it could be as wide as the endobronchial balloon itself. The tracheal cuff 12, if present, should also be of high-volume low-pressure design. When bilateral ventilation is required, ET 2 is withdrawn slightly after the EB 8/8' is completely deflated.

[0042] The sizes of EB 8/8' should be such that upon inflation, it should reach a dimension compatible with the size of the child and the child's endobronchial dimension (Table 1) with inflation pressure <25 cmH₂O. [0043] The structure EB 8/8' may be similar to the well known EB in the art such as the Arndt 5F EB (Arndt Endobronchial Blocker®, www. cookgroup .com, http://www.cookmedical.com/cc/dataSheet.do?id=1318) or a Fogarty embolectomy catheter [Edwards Lifesciences, USA

(http://www.edwards.com/products/vascular/clotmanagement/embolectomycatheter.htm)]. However, the endobronchial balloon or blocker as provided herein preferably does not have a stem through the center thereof like the Arndt and Fogarty and is broad-based.

[0044] For a small endotracheal tube 2, if necessary, such as using current available endotracheal tubes and Fogarty/Arndt blockers, their tip or outlet 9 should be carefully enlarged and trimmed to reduce airflow resistance (refer to panels b and c of Figure 7 or panel a of Figure 8).

[0045] Table 1 shows airway dimensions in children (From: Hammer GB₅ et al: Anesth Analg 1999; 89(6): 1426-9). The average mean tracheal AP (saggital) diameters are given, as this dimension determines the "limiting diameter" (i.e., largest size tube admissable). The bronchial diameters are calculated from the measured bronchial tracheal ratios of 0.86 (right bronchus) and 0.66 (left bronchus) in children. NA = not applicable. ^aRespiration and circulation (biological handbooks). Bethesda, MD: Federation of American Societies for Experimental Biology, 1971 :105-8. ^bGriscom NT, Wohl MEB. Dimensions of the growing trachea related to age and gender. AJR Am J Roentgenol 1986;

146: 233-7.

Table 1. Airway Dimensions in Children

Expected Expected Expected Expected right bronchial left bronchial right bronchial left bronchial

Age Trachea" diameter diameter Trachea* diameter diameter

(F) (mm) (mm) (mm) (mm) (mm) (mm)

0.5-1 5.6 4.8 3.7 N/A N/A N/A

1-2 6,5 5.6 4,3 5,3 4.6 3.5

2-4 7.6 6.5 5.0 7.4 6.4 4.9

4-6 8.0 6.7 5.3 8.0 6.7 5.3

6-8 9.2 7.9 6,1 9.2 7.9 6.1

8-10 9.0 7,7 6,0 10.5 9.0 6.9

10-12 9.8 8.4 6.5 11.6 10.0 7.0

12-14 10.3 8.6 6.8 13.0 11.2 8.6

14-16 12.7 10.9 8.4 13.9 12.0 9.2

16-18 NA NA NA 13.7 14.6 9,0

18-20 NA NA NA 13.9 12.0 9.2

The average mean tracheal AP (saggital) diameters are given, as this dimension determines the "limiting diameter" (i.e., largest size tube admissable). The bronchial diameters are calculated from measured brandtiatacheal ratios of 0,86 (right bronchus) and 0.66 (left bronchus) in children (1). NA = not applicable. " See Reference 1. ' See Reference 2. [0046] In one embodiment, as shown in Figure 8, the tubing 11 of EB 8/8' can be placed or incorporated with the ET 2 inside or outside of the ET' s lumen. Placing the tubing 11 inside or outside of the ET depends on the size of the ET 2. The tubing 11 or a conduit is placed inside the ET 2 lumen if the ET 2 lumen is wide enough. For very small children, the use of a very small ET 2 (<5 mm internal diameter) would necessitate placing the tubing 11 or a conduit outside of the lumen of ET 2. It is preferable to place the tubing 11 within the lumen if the size of the ET 2 allows, provided that the ET 2 must be wide enough to accommodate the tubing 11 and allow air flow and fiberoptic bronchoscopy.

[0047] As shown in Figure 8, the co-axially placed tubing 11 is pre-placed within the ET 2 with the EB 8/8' protruding through a Murphy eye or a small opening 4a (panel b of Figure 8), or, if the blocker tubing 11 is extra-luminal, with the balloon protruding entirely through a Murphy eye or a small opening 4a (panel a of Figure 8). The EB 8/8' at inflated state is bigger than the Murphy eye or the opening 4a in size so that the EB 8/8' cannot retrogradely migrate through the Murphy eye or the opening 4a of the ET 2. Optionally, the tubing 11 of the EB 3 can be built in the ET inside or outside of the ET's lumen, preferably inside the lumen.

[0048] This new ET-EB device improves safety and ease of successful and uninterrupted lung isolation. It should be a welcome addition to the armamentarium of pediatric anesthesiologists. Pediatric surgeons would welcome it too as they would be able to have uninterrupted lung isolation and superior surgical conditions. Small children would benefit as they would more likely to be able to have successful minimally invasive thoracic procedures, thus avoiding many of the problems that have already been mentioned above. This new ET-EB device has the potential of becoming the ET-EB device of choice in all thoracic surgeries for children under the age of 6-8 years. It may also become a contender among devices for adult one-lung isolation.

[0049] Summary of Potential Benefits of this New Endotracheal Tube Design as shown in figures 4-6:

1. Elimination of retrograde migration of endobronchial blocker during thoracic surgery requiring one-lung anesthesia in small children; 2. Reduction of intubation and endobronchial blocker placement time since the new device is placed as one unit;

3. Ease of endobronchial blocker placement;

4. Reduced requirement to confirm final position of tube and endobronchial blocker with fiberoptic bronchoscopy; it would thus be possible to isolate a lung even when this new ET of internal diameter of 2.5 mm is used (the smallest fiberoptic bronchoscope currently in use at the Prince of Wales Hospital has an outside diameter of 1.8 mm and could not pass through a 2.5 mm ET);

5. Because this new ET 's tip abuts the carina and ventilates the left lung directly, it should also isolate most, if not all, of the tracheoesophageal fistulas encountered in clinical practice without the need for an extra blocker placed inside the fistula.⁴

6. Because the endobronchial balloon of this new ET is long and has a high filling capacity and is tailored made for each size of ET, there should be less ball-valve effect⁸ leading to partial ventilation of the collapsed lung (ball valve effect is caused by the slight dilatation of the bronchus during inspiration and slight contraction of the bronchus during exhalation, causing air trapping).

7. Reduced airway resistance through the endotracheal tube because of the lack of a conventional bronchial blocker within its lumen. Currently, the catheter of the bronchial blocker may pass within the lumen of the endotracheal tube, increasing airway resistance and making it difficult or impossible to simultaneously pass a suction catheter or a fiberoptic bronchoscope.

8. Reduced pressure on the mucosa of the trachea, thereby reducing the chance of ischemia and necrosis of the tracheal wall, and the chance of tracheal scarring and stenosis. Currently, in very small children, infants, and premature babies, the endobronchial blocker needs to be on the outside of the endotracheal tube, and this adds pressure on the tracheal wall. This new device has no added catheter outside the endotracheal tube and thus has less chance of that damage.

9. Because of the built in angle (α) between the long axis of the endotracheal tube and the long axis of the endobronchial balloon in an inflated state, placement of the endobronchial balloon in the chosen mainstem bronchus is easily done by rotating the device such as turning the device by 180 degrees such that the endobronchial balloon blocker faces the correct direction. This is an advantage over current practice as catheters prefer to enter the right mainstem bronchus because of a less acute angle it sustains with the trachea. Current techniques are harder to implement when one needs to place the balloon blocker in the left mainstem bronchus.

EXAMPLES

[0050] The device as provided herein has been described in substantial detail with reference to Figures 4-6. By way of illustration, the concept of incorporating the endobronchial balloon at or near the tip of the ET was tested out using existing equipment.

Materials and Methods

[0051] It is hypothesized that the tendency of the EB to retrograde-dislocate could be minimized by anchoring or incorporating the stem of the blocker to the Murphy eye of the endotracheal tube (ET). This could be effected with the balloon-tipped catheter within (coaxially, Fig. 7a) or outside (Fig. 7b and 7c) the lumen of the ET. This technique in children presenting for thoracic anesthesia was investigated at Prince of Wales Hospital (Shatin, NT, Hong Kong SAR, PRC).

[0052] Ethics approval was obtained from the Chinese University of Hong Kong-New Territories Eastern Cluster Ethics Review Board. All patients too small for the DLT or the Univent tube requiring one-lung anesthesia were eligible. An EB technique would have been chosen irrespective of consent. Exclusion criterion was when the child would require a 2.5 mm ID ET as flexible bronchoscopy using our fiberscope (external diameter 1.8 mm) would be extremely difficult.

[0053] Preparation for intubation consisted of the following for an ET with internal diameter (ID) >4-5 mm: the EB, either an Arndt 5F EB or a Fogarty embolectomy catheter, was passed through the lumen of the ET with the balloon emerging through the Murphy eye (Fig. 8b); the passage of both the selected EB and an 18-mm pediatric fiberscope (Olympus LF, Tokyo, Japan), both lightly lubricated, simultaneously through the lumen of the selected ET was tested for ease of sliding movements; the ET-EB unit was assembled with an Arndt Multiport Adaptor (Cook Incorporated, Bloomington, IN) prior to intubation in the standard fashion.⁹ When an ET with ID <4 mm was used, preparation comprising: the lightly lubricated EB was outside the lumen of the ET and was threaded through the Murphy eye and protruding completely (Fig. 8a); the distal opening of the ET was trimmed at an angle to reduce airflow resistance (Figs. 7b-6c and Fig. 8b).

[0054] Standard monitors of blood pressure cuff, ECG, SpO₂ were applied in all cases. All children were induced with sevoflurane or thiopentone. Except for the case of tracheoesophageal fistula (TEF), intubation was facilitated with atracurium. TEF patients received lignocaine spray of the airway but no relaxant. Maintenance was with isoflurane, atracurium, fentanyl, and ventilation was with air and oxygen to maintain an oxygen saturation >90-95%.

[0055] During placement through the larynx, the ET-EB unit was orientated such that the balloon pointed toward the bronchus for blockade. Prior to intubation, A mental picture of the orientation of the markings on the ET was recorded to help ensure that it and the EB were orientated correctly once they were placed. Changing the direction of the blocker in situ, when necessary, was achieved by rotating the ET-EB unit as a whole.

[0056] Once the ET-EB unit was inserted and the blocker was positioned in the desired mainstem bronchus, the blocker was inflated with air until it appeared fiberscopically to completely occlude the bronchus. Further adjustments of balloon volume were made after the lung was collapsed. For the right mainstem bronchus, no attempt was made to prevent distal portion of the EB from overriding a portion of the right upper lobe orifice. In so doing, the likelihood of dislodgement into the trachea was reduced (the margin of safety applied to DLT placement¹⁰'¹¹ was modified here).

[0057] All EB placements were facilitated with a fiberscope with an outside diameter of 1.8 mm, and further confirmed by observation and auscultation. To facilitate uninterrupted positive pressure ventilation during fiberscope-assisted EB placement using the Arndt Multiport Adaptor, a reducer for minimal invasive surgery with a 2/3 -mm pinhole (Mini Step, InnerDyne, Salt Lake City, Utah) was used to prevent leak at the

10 fiberscope port.

Results

[0058] The above techniques were used in eight thoracic cases (Table 2) involving eight patients, all of whom were too small for a DLT or Univent® tube. In five cases (1-4,8), the EB was inside the lumen of the ET. In three cases (5-7), the blocker was outside the lumen of the ET. In all cases, the Murphy eye of the ET was trespassed by the stem of the EB as shown in Fig. 7 and Fig. 8.

[0059] None of the patients had difficult laryngoscopic view. In Cases 1-4,5, the fact that the balloon tip was partially protruding through the Murphy eye did not add significantly to the complexity of the intubation, and the ET-EB unit passed through the larynx easily in all five cases. Once placed, the EB could be slid distally or proximally with relative ease, with due care taken not to pull the EB into the ET lumen. When the EB catheter was outside the ET lumen (Cases 5-7), the Arndt Multiport Adaptor needed not be attached during intubation, and it was found that passing the unit through the larynx and also sliding the blocker for positioning were easier when the blocker was initially positioned such that it had completely passed through the Murphy eye (Fig. 8b). Again, the intubation was not made difficult by the presence of the EB. When the Arndt 5F EB was used, the wire loop was not attached to the fiberscope prior to intubation.⁹ In all cases, the EB slid easily into the chosen bronchus.

[0060] Lung isolation was achieved in all eight cases. In Cases Ia and 4, gradual inflation of the blocked lung occurred because of the ball- valve effect created by the EB (bronchial luminal diameter is larger during inhalation and smaller during exhalation ). This problem was overcome in Case 4 by reducing the inspiratory pressure (and increasing the respiratory rate), and by asking the surgeon to compress the lung (Case Ia). Retrograde migration or excessive EB herniation into the tracheal lumen did not occur in five cases. In one case (6), the EB did retrograde dislodge into the trachea and had to be repositioned five times, all within a period of about one hour during the operation. During that case, the surgeons had inadvertently lacerated the pulmonary vein and there was profuse bleeding. They had to apply strong retractions and manipulations of the right lung in order to stop the bleeding. It was during those intense mechanical distortion of the right lung when the blocker retrograde-dislodged. It took an hour for the surgeons to finish the repair, during which the patient's hemoglobin dropped from 13.5 to 9.3 g/dl (no blood transfused). The EB did not dislocate during the rest of the case.

Discussion

[0061] Disclosed is the preliminary experience with a novel technique for preventing retrograde dislodgement of an EB into the trachea in small children. This problem is well recognized when Fogarty embolectomy blockers are used,¹ although the incidence is unknown. Even with the recently availability low-pressure high-volume balloon catheter (Arndt 5F), this problem still occurred in 3 (13%) out of a series of 23 cases.² The margin of safe EB placement probably diminishes with endobronchial length. Retrograde dislodgement of the EB into the trachea leads to loss of lung isolation, interruption of surgery, and airway obstruction. Cardiac arrest has been described in an adult case.⁷ Blocker repositioning is cumbersome in a small child lying on the side with the head and neck partially draped and in close proximity with the surgical field. Fiberoptic bronchoscopy is required for repositioning and, unless a reducer is used, the lack of an airtight adapter means interruption of ventilation. If the problem recurs, the increase in surgical time and trauma to the collapsed lung may be significant.

[0062] Retrograde dislodgement of the balloon is not a problem with the DLT. In spite of the higher incidences of minor airway injuries (relative to balloon-tipped catheters),⁵ the DLT remains a popular choice amongst anesthesiologist, in part, because maintaining it's EB in the mainstem bronchus is easier and the resulting surgical conditions superior.⁵ This improved reliability, we speculate, is due to the solid support of the EB by the rigid bronchial stem of the DLT, and the fact that the majority of the mainstem bronchus is occupied by a stiff endobronchial stump. In contrast, in the case of a balloon-tipped catheter, most of the mainstem bronchus is occupied by a balloon supported by a thin flexible stem anchored at the other end outside the patient's mouth. A proximal movement of a mere fraction of a cm at the distal end, enough to cause the EB to pop into the trachea in a small child, barely increases the bent in the stem of the catheter. Whether the catheter is within or outside the ET lumen, this small increase in the bent is easily accommodated. In other words, the distance between the balloon and its anchor is too far. If this assumption is valid, then anchoring the EB at the tip of the stiffer ET (stented by the trachea), and the increased bent necessitated by this arrangement, which reduces the room for further bending of the catheter, should reduce the likelihood of retrograde EB movement. The extra support appeared to have discouraged retrograde movement of the EB but still allowed the catheter to be advanced or retracted without requiring a great deal of force. Case 4 provides the best support to this contention. We were able to use one EB to block both the right mainstem bronchus and a presumed ectopic right upper lobe bronchus (Fig. 10) without the EB popping into the trachea, even though a substantial portion of the balloon was already outside the right mainstem bronchus. It was also possible that retrograde movement of the EB was actually prevented by the tip of the ET. This was made possible only because the EB had emerged through the Murphy eye rather than the tip of the ET lumen, in which case serious obstruction to airflow would have occurred. Although the right lung of an adult with an ectopic right upper lobe bronchus at the carina has been successfully blocked with one EB,¹⁴ we believe that such a feat is difficult to achieve in a small child without the additional safety margin afforded by our technique. Unfortunately, when there is excessive retraction and manipulation of the lung, the dislocation of the EB could still occur, as demonstrated in Case 6.

[0063] Another disadvantage of the balloon-tipped catheter technique in one-lung anesthesia is the incomplete collapse of the blocked lung.⁵' This appears to be due to a ball-valve effect.¹³ Increasing the balloon inflation volume may help, as demonstrated in Case Ib. This is, however, a finicky process. Excessive inflation of the balloon theoretically increases the risk of bronchial rupture,¹⁵'¹⁶ although recent data suggest that not all of the intra-balloon pressure is transmitted to the mucosal wall of the bronchus.¹⁷ High balloon pressure may also increase the tendency of the balloon to pop into the trachea. Thus, lest our Murphy eye technique should inadvertently allow clinicians to over-inflate the bronchial balloon without causing it to pop into the trachea, It will not be emphasized enough that inflation of the EB should be just enough to avoid ventilation of the collapsed lung, but not beyond. Another technique of avoiding a ball-valve effect at the collapsed lung, especially if surgery is not excessively long, is by reducing the inspiratory pressure (Case 4), or by asking the surgeon to compress the lung (Case Ia), or by intermittently deflating the balloon to allow the non-dependent lung to collapse again. Removing the wire loop of the Arndt blocker and suctioning the lumen or leaving it open to air may also help.

[0064] The Arndt Multiport Adaptor has a fiberscope port with an opening too big for a 1.8 mm fiberscope. To allow uninterrupted ventilation, a Mini Step adaptor with a pin hole¹² is added to it and used a spare Arndt fiberscope port cover during normal ventilation. These pieces of accessories are now standard components in our pediatric thoracic trolley.

[0065] One bonus of the Murphy eye technique of the invention is that the angulated orientation of the catheter tip makes intubation of the chosen mainstem bronchus easy. It will be sure that a mental picture of the theoretical post-intubation orientation of ET is formed before the ET-EB unit was inserted, with the catheter tip either facing the right or the left, depending on which lung needed to be collapsed. In spite of this ease, It is recommended that the wire loop at the end of the Arndt EB be not removed unless suctiom^'ng or O₂ insufflation is required during surgery.

[0066] It is preferred to pass the bronchial blocker through the lumen of the ET and out through the Murphy eye if the size of the patient allows a big enough ET (non-cuffed ETs are therefore preferred). This way, an extra source of pressure on the tracheal mucosa is avoided. An ET 4 mm ID₅ found in the invention (Case Ia), could accommodate a 4F Fogarty embolectomy catheter and a 1.8 mm fiberscope simultaneously, but ventilation during bronchoscopy was difficult. An ET 4.5 mm ID could accommodate an Arndt 5F catheter/Fogarty 4F embolectomy catheter and a 1.8 mm fiberscope simultaneously and allow ventilation. Because blockers and fiberscopes come in various diameters, anesthesiologists should test to see if the chosen blocker and fiberscope can simultaneously slide within the chosen ET(s) with ease before starting the anesthetic. Sometimes the ET appropriate for the child is too small to allow the bronchial blocker to be passed within the ET lumen. The advantages of having the blocker stem outside the ET are that it can be used in very small children (as in Case 4), and it does not increase flow resistance through the ET or need an Arndt multiport adapter (a standard swivel bronchoscopic adapter with a Mini Step reducer¹² would suffice). The additional pressure on the tracheal mucosa from the additional catheter is a concern although anecdotes suggest that it may be well tolerated.⁴'¹⁸'¹⁹ The tip of a smaller ET (Figs. 7b-6c and 8a) should be trimmed to reduce flow resistance.

[0067] An alternative to the use of EB is to simply intubate the ventilated lung with the in situ ET. There is, however, no guarantee that the ET would not be too big or too small for the selected mainstem bronchus,⁴ a problem usually discovered after surgery has begun. Fiberoptic bronchoscopy may be required to reintubate the selected mainstem every time the ET is retracted for bilateral ventilation. If a cuffed pediatric ET is used, the cuff may block branches of the mainstem bronchus. The lack of access to the non-ventilated lung is also a concern. For these reasons, an EB is the technique of choice of many pediatric anesthesiologists.

[0068] In summary, passage of the bronchial blocker through the Murphy eye of an ET tube may reduce the likelihood of retrograde dislodgement of the blocker into the trachea. The preliminary experience of the invention suggests that the technique is viable and adds little, if any, additional risk to the procedure. Designs of pediatric blockers which incorporate the EB into the body of the ET (near or at its tip) will have a better effect than the passage of EB through the Murphy eye of an ET tube.

[0069] While the above descriptions contain many specifics, it should not be considered as limitation of the scope of the invention. Modifications may be made to the foregoing without departing from the basic aspects of the invention. Although the invention has been described with reference to one or more specific embodiments, those of skill in the art will recognize that changes may be made to the embodiments specifically disclosed in this application, yet these modifications and improvements are within the scope and spirit of the invention, as set forth in the claims which follow.

[0070] Citation of the above publications or documents is not intended as an admission that any of the foregoing is pertinent prior art, nor does it constitute any admission as to the contents or date of these publications or documents. The publications or documents referenced herein are hereby incorporated by reference.

Table 2. Cases Summaries Involving the Use of Endobronchial Blockers (EBs)

to

Table 2 shows the case summaries involving the use of endobronchial blockers (EBs). All passed through the Murphy eye of the endotracheal tube (ET) to achieve one-lung ventilation. All cases were performed entirely thoracoscopically except for Cases 4 and 5, which were converted to a thoracotomy. CCAM = congenital cystic adenomatoid malformation. ID = internal diameter. LUL = left upper lobe. RUL = right upper lobe. TEF = tracheoesophageal fistula

REFERENCES

[0071] 1. Hammer GB. Single-lung ventilation in infants and children. Pediatr Anesth 2004; 14:98-102

[0072] 2. WaId SH, Mahajan A, Kaplan MB, Atkinson JB. Experience with the Arndt paediatric bronchial blocker. Br J Anaesth 2005; 94: 92-4

[0073] 3. Bird GT, Hall M₅ NeI L, Davies E, Ross O. Effectiveness of Arndt endobronchial blockers in pediatric scoliosis surgery: a case series. Pediatr Anesth 2007; 17:289-94

[0074] 4. Ho AMH, Wong J, Chui PT, Karmakar MK. Case Report: Use of two balloon-tipped catheters during thoracoscopic repair of a type C tracheoesophageal fistula in a neonate. Can J Anesth 2007; 54:223-6

[0075] 5. Knoll H, Ziegeler S, Schreiber J-H, Buchinger H, Bialas P, Semyonov K, Graeter T, Mencke T. Airway injuries after one-lung ventilation: A comparison between double-lumen and endobronchial blocker. Anesthesiology 2006; 105:471-7

[0076] 6. Campos JH, Hallam E, Van Natta T, Kernstine KH. Devices for lung isolation used by anesthesiologists with limited thoracic experience. Anesthesiology 2006; 104:261-6

[0077] 7. Sandberg WS. Endobronchial blocker dislodgement leading to pulseless electrical activity. Anesth Analg 2005; 100:1728-30

[0078] 8. Jaureguizar E, Vazquez J, Murcia J, Diez Pardo JA. Morbid musculoskeletal sequelae of thoracotomy for tracheoesophageal fistula. J Pediatr Surg

1985; 20: 511-4 [0079] 9. Arndt GA, Kramer PW, Rusy DA, Love R. Single-lung ventilation in a critically ill patient using a fiberoptically directed wire-guided endobronchial blocker. Anesthesiology 1999; 90:1484-6

[0080] 10. Benumof JL, Partridge BL, Salvatierra C, Keating J. Margin of safety in positioning modern double-lumen endotracheal tubes. Anesthesiology 1987;67:729-38

[0081] 11. Ho AMH, Karmakar MK, Lam WW, Lam FO, Lee TW, Ng SK, Chung DC. Does the presence of a tracheal bronchus affect the margin of safety of double-lumen tube placement? Anesth Analg 2004; 99:293-5

[0082] 12. Ho AMH, Karmakar MK. A simple addition to the swivel and Arndt multiport adapters to facilitate fibreoptic bronchoscopy in small children. Ann Roy Coll Surg Engl 2007; 89:532-3.

[0083] 13. Ho AMH, Soo G, Lee S, Chung DC₅ Critchley LAH, Karmakar MK. Airway obstruction after peanut aspiration - air trapping is due to airway distension and narrowing. Can J Anesth 2005; 52:205-6

[0084] 14. Kin N, Tarui K, Hanaoka K. Successful lung isolation with one bronchial blocker in a patient with tracheal bronchus (letter). Anesth Analg 2004; 98:270

[0085] 15. Yuceyar L, Kaynak K₅ Canturk E, Aykac B. Bronchial rupture with a left-sided polyvinylchloride double-lumen tube. Acta Anaesthesiol Scand 2003; 47:622-5

[0086] 16. Borchardt RA, LaQuaglia MP, McDowall RH, Wilson RS. Bronchial injury during lung isolation in a pediatric patient. Anesth Analg 1998; 87:324-5

[0087] 17. Roscoe A, Kannellakos GW, McRae K, Slinger P. Pressures exerted by endobronchial devices. Anesth Analg 2007; 104:655-8

[0088] 18. Reeves ST, Burt N, Smith CD. Is it time to reevaluate the airway management of tracheoesophageal fistula? Anesth Analg 1995; 81 :866-9

[0089] 19. Filston HC, Chitwood WR Jr, Schkolne B, Blackmon LR. The Fogarty balloon catheter as an aid to management of the infant with esophageal atresia and tracheoesophageal fistula complicated by severe RDS or pneumonia. J Pediatr Surg 1982; 17:149-51

Claims

1. A device (1) for single-lung anesthesia in infants or small children comprising an endotracheal tube (ET) (2), an endobronchial blocker (EB) (8/8') and a port (6) for inflating the EB (8/8') through a tubing (11), wherein the EB (8/8') is incorporated or anchored into a distal portion (4) of the ET (2), whereby preventing retrograde migration of the EB (8/8').

2. The device of claim 1, wherein a base (7) of the EB (8/8') is incorporated or built into the distal portion (4) of the ET (2).

3. The device of claim 1 further comprising tracheal cuff (12) which is located near the distal end of ET (2) and is inflated through the a port (14) via a tubing (13).

4. The device of claim 1 or 2, wherein the port (6) is a standard self-sealing port injected with a syringe, and allows injection or extraction of gas or air or fluid when the syringe is connected, but seals once the syringe is disconnected.

5. The device of claim 3, wherein the port (14) is a standard self-sealing port injected with a syringe, and allows injection or extraction of gas or air or fluid when the syringe is connected, but seals once the syringe is disconnected.

6. The device of any one of claims 1-5, wherein the long axis of the EB (8/8'), when the EB (8/8') is inflated, has a natural angle (α) of about 30-60° to the long axis of the ET (2).

7. The device of claim 1 or 2, wherein the EB (8/8') is made from a biocompatible elastomeric material selected from a group consisting of polyurethane, silicone, and rubber of silicone plastic.

8. The device of claim 3, wherein the endobronchial cuff (12) is made from a biocompatible elastomeric material selected from a group consisting of polyurethane, silicone, and rubber of silicone plastic.

9. The device of any one of claims 1-8, wherein the infants or small children are age 0 up to age of 6-8 years, or newborns or premature infants.

10. The device of any one of claims 1-8, wherein the device can be made into sizes suitable for larger children or adults.

11. The device of any one of claims 1-10, wherein the EB (8/8') is incorporated or securely anchored into a distal portion (4) of the ET (2) using medical grade adhesive, or through a Murphy eye or a small opening (4a).

12. The device of any one of claims 1-11, wherein the internal diameter of ET (2) is in sizes ranging from 2.5 mm to 9 mm.

13. The device of claim 12 wherein the size of the internal diameter of ET (2) is in 0.25 mm increments.

13. The device of claim 1, wherein the EB (8/8') has a wide neck (7) to prevent kinking and to provide support.

14. The device of claim 1 or 2, wherein the tubing (11) connecting the EB (8/8') is placed or incorporated into at least a part of the wall of the ET (2) inside or outside of the ET' s lumen.

15. The device of claim 3, wherein the tubing (13) connecting tracheal cuff (12) is placed or incorporated into at least a part of the wall of the ET (2) inside or outside of the ET' s lumen.

16. The device of any one claims 1-15, wherein a distal end (5) of the ET is further comprised in the ET (2), and is not pointy, and has a somewhat flat to slightly concave-outward shape to improve its contact with the carina and to discourage the device from being inadvertently or too easily pushed into one of the mainstem bronchi.

17. The device of any one claims of 1-16 further comprising an end opening (9) in the ET (2), wherein the end opening (9) is slanted and faces toward the side opposite to that of the endobronchial blocker (8/8').

18. A method of single-lung anesthesia in infants or small children comprising intubating a device (1) of any one of claims 1-17 in the infants or small children, wherein a retrograde migration of an endobronchial blocker comprised in the device does not occur.

19. The method of claim 18 further comprising: inserting the device until the distal end (5) of ET (2) abut the carina so that resistance is met at an insertion distance commensurate with the size of the infants or small children, and inflating the EB (8/8') until ventilation of a blocked lung ceases whilst the other lung continues to be ventilated.

20. The method of claim 19 further comprising placing the EB (8/8') in the chosen mainstem bronchus by rotating the device (1) such that the endobronchial balloon blocker (8/8') faces the correct direction.

21. The method of claim 20, wherein the step of rotating the device (1) comprises turning the device (1) by 180 degrees.

22. The method of claim 21, wherein the endobronchial blocker 8/8' is deflated first, if the rotation must be made with the device already inside the tracheobronchial tree.

23. The method of any one of claims 18-22, wherein the infants or small children are age 0 up to 6-8 age, or newborns or premature infants.

24. A method of producing a device (1) of any one of claims 1-17 comprising incorporating or anchoring the EB (8/8') into the ET (2)'s distal portion (4).