Effects of Suctioning on Mucociliary Transport

Effects of Suctioning on Mucociliary Transport* Jose F. Landa, M.D., F.C.C.P.; Mark A. Kwoka, M.D.; Gillete A. Chapman, M.D .; Miguel Brito, M.D.; and Marvin A. Sackner, M.D., F.C.C.P.

We previously have shown that the mucosa of the air· ways is injured after suctioning, but the etfed of this damage on mucus transport has not been systematic:ally Investigated. We measured bronchial mucus velocity of conscious sheep after trac:heostomy and bronchial mucus velocity after suctioning the bronchi with three dif. ferent catheters (Bard side end-hole, Aero-Flo, and Tri. F1o catheters). Tracheostomy in sheep produced a significant depression of right and left bronchial mucus veloc:ity three hours after surgery, but at l4 hours, this measurement returned to baseHne and remained at this value seven to ten days later. Interrupted suction in a preselected bronchus every ten minutes for three hours

A !though prolonged endotracheal intubation has

been used since the early 1940s, the trauma to the mucosa which produces erosions, ulcerations, tracheal stenosis, and tracheomalacia has only been well recognized in the last decade. 1 The vulnerability of the tracheobronchial mucosa to minimal trauma was emphasized by Hilding and Hilding,2 who reported extensive desquamation of the mucosa after light rubbing of the airway's mucosa with gauze and cotton swabs. Our laboratory has reported that suctioning catheters employed to aspirate secretions from the airway cause mucosal denudation, edema, and inflammatory exudates due to invagination of the mucosa into the holes of the catheter( s) . The occurrence of such lesions is minimized by an improved design of the suctioning catheter to prevent contact of the holes of the catheter with the mucosa of the airways. In the Aero-Flo catheter, this is accomplished by an expanded tip on the catheter, with four small holes located immediately proximal to the tip. 3 The occurrence of mucociliary dysfunction probably depends on the severity and extent of mucosal damage; for example, inflated cuffed endotracheal tubes depress tracheal mucus velocity one hour • From the Division of Pulmonary Disease, Department of Internal Medicine, Mount Sinai Medical Center, Miami Beach, FL. Supported in part by grant HL-17816 from the National Heart, Lung, and Blood Imtitute and by Sherwood Medical Cotp. Reprint requests: Dr. Landa. Mount Sinai Medical Centef', 4300 Alton Road, Miami Beach 33104

202 LANDA ET AL

in eight sheep caused significant decreases in bronchial mucus velocity at 3, 6, and l4 hours when the Bard catheter was employed but much less of a faD with the Aero-Flo catheter. Interrupted suction for six hours in five sheep produced less of a decrease in bronchial mucus velocity at six hours for the Aero-Flo catheter than for the Tri-Fio catheter. We conclude that suctioning catheters with tips designed to minimize mucosal contact are less injurious to mucus transport than conven- . tional side end-hole suctioning catheters and that the Aero-Flo tip is superior in design to the Tri-Fio tip, which also incorporates features to minimize damage to the mucosa of the airways.

after insertion in anesthetized dogs. 4 Mucus transport might be preserved with less severe injury resulting from tracheobronchial instrumentation, despite histologic evidence of mucosal damage.:s-7 The purpose of the present investigation was to ascertain whether suctioning procedures to the tracheobronchial tree would affect mucus transport. MATERIALS AND METHODS

Material and Preparation Thirteen female sheep, weighing from 24 to 45 kg, were selected. A tracheostomy was used to gain access into the tracheobronchial tree. The animals were placed into a modifled metal shopping cart, and a metal sling was used to restrain the head. The eyes were occluded by a blinder to minimize apprehension. The shopping cart was tilted to permit exposure of the neck. The skin was shaved and scrubbed with a povidone-iodine solution ( Betadine). Local anesthesia was achieved with a 1 percent solution of lidocaine. A vertical incision was made midway between the angle of the jaw and the sternal notch. The trachea was exposed, and part of the fourth or fifth cartilage was removed so that a plastic, fenestrated tracheotomy tube (Shiley No. 6) could be inserted. The orifice of the tube was occluded at all times except during the suctioning procedures, in order to permit the animal to breathe naturally. The cuH was inflated only for one hour after tracheostomy.

Bronchial Mt1Ct18 Velocity Bronchial mucus velocity was determined by a modification of a roentgenographic method previously de3Cribed. a Teflon was rendered radiopaque by mixing with 50 percent reagent-grade bismuth trioxide powder and was compressed

CHEST, 77: 2, FEBRUARY, 1980

into tape 0.64 em wide and 0.08 em thiclc ( Chemplast, Inc.). Disks 1 mm in diameter and 0.8 mm thiclc were manufactured with a hand-operated punch and were blown through the inner channel of a ftberoptic bronchoscope onto the bronchial mucosa. The bronchus containing the disks was visualized in the lateral projection with a television monitor ( Conrac Corp. ) connected to a portable image-intensifier unit (Toshiba Surgical X-Ray Television Unit SXT6). The motion of the disks was recorded on videotape (International Video Corp) while time from a digital cloclc ( Vicon Industries) was also displayed. One centimeter lengths of radiopaque Teflon tape were placed on the skin ot the right and left hemithoraces overlying the bronchi. The mean of the two lengths of tape on the videotape image was used as the reference distance, in order to allow for the magnification by the fluoroscopic imageintensifier. A test for validity of this procedure was accomplished by placing a length of radiopaque tape within the bronchus and comparing this measurement to the value obtained by the calibration procedure. The agreement between the two methods was within 1 percent of the length of tape. The velocity of the disks was computed from the videotape by measuring distance traveled over 30 to 60 seconds at the position of functional residual capacity. Bronchial mucus velocity was calculated from the average of the velocities of 15 to 25 individual disks.

Procedure In the first set of experiments, we set out to study the effects of tracheostomy on bronchial mucus velocity. Measurements were obtained in eight animals the morning immediately prior to tracheostomy and at 3, 24, and 30 hours and seven to ten days later. In the second set of experiments (same eight animals) , the effects of suctioning on bronchial mucus velocity of a No. 14F side end-hole suctioning catheter (Bard Inc.) were compared to a No. 14F beaded suctioning catheter (AeroFlo; Argyle Division, Sherwood Medical) (Fig 1). One of the two suctioning catheters was selected at random. It was inserted into the tracheostomy tube with a fiberoptic bronchoscope (Medi-Tech F0/2.5/83) within it, so that the suctioning catheter could be placed in a predetermined right or left main bronchus under direct visual observation. Between procedures and in order to mlnimire

A

B

manipulation, the suctioning catheter was secured with adhesive tape to avoid displacement, and its position was checlced immediately prior to each suctioning procedure with the fiberoptic bronchoscope. The suctioning catheters were connected to a vacuum source in which 100 mm Hg of negative pressure was repetitively applied by occluding the proximal vacuum regulator of the catheter intermittently and advancing and retracting the catheter as in a clinical situation. This procedure was repeated every ten minutes for three hours. Bronchial mucus velocities were estimated prior to suctioning, at the end of suctioning, and 3 and 24 hours later in both the suctioned and nonsuctioned bronchi. Mter carrying out suctioning with one of the catheters, the sheep were allowed to recover for at least one week. The catheter to be compared was then inserted in the contralateral bronchus, and the procedure was repeated. In the third set of experiments (five animals), the effects on bronchial mucus velocity of a Tri-Flo suctioning catheter (Pharmaseal, Inc) (Fig 1) were compared to the Aero-Flo suctioning catheter. A procedure similar to the one used for comparison of the Bard side end-hole catheter with the AeroFlo catheter was followed. Interrupted suctioning was applied every ten minutes for six hours. Measurements of bronchial mucus velocity were estimated prior to the beginning of suctioning, at the end of the six hours of suctioning, and at 24 hours. Statistical Analysis

An analysis of variance was performed as a two-factor (procedure; time of measurement) experiment, with repeated measurements on one factor (time) .e To test the null hypothesis of no difference between procedures, a pairwise comparison was made of the treatments at each level of the time factor using Duncan's new multiple ~e test.1o

fu:suLTS Right os Left Main Bronchi All baseline observations of bronchial mucus velocity (prior to tracheostomy) for the 13 sheep studied are shown in Figure 2. All but one of these values fell within 25 percent of the line of identity.

c

FIGURE 1. A, No. 14F Tri-Flo suctioning catheter. B, Bard No. 14F side end-hole suctioning catheter. C, No. 14F Aero-Flo suctioning catheter.

CHEST, 77: 2, FEBRUARY, 1980

EFFECTS OF SUCTJONING ON MUCOCIUARY TRANSPORT 203

Table 1-Traeheo.lomy tmd BronehiaJ Muew J'eloeity in Ri•lat a11d Left Main Bronehi

Time after Tracheostomy

Bronchial Mucus Velocity, mm/min* Right Bronchus

Left Bronchus

12.5±3.6

12.7±3.6

Baseline 3 hr

8.2±4.5**

7.2±2.9**

24 hr

13.5±4.5

12.6±3.2

30 hr

12.8±3.9

11.5 ±3.2

7-10 days

14.2±4.1

13.7±3.7

,..

25

>

20

.... u ...0....

-25"

;:) "'

0 u

;:)

~ I

;:) "'

c "i 15

........

E E

:z:

10

•• .......

5

u z 0

.......

*Mean± SD. **P <0.05, compared to baseline.

Effect of Tracheostomy

10

5

Baseline mean bronchial mucus velocity prior to tracheostomy was 12.5 mm/ min in the right main bronchus and 12.7 mm/min for the left (Table 1). At three hours after tracheostomy, the average bronchial mucus velocity decreased to 8.2 mm/ min in the right and to 7.2 mm/min in the left bronchus, a fall of approximately 38 percent ( P < 0.05). At 24 hours, bronchial mucus transport had returned to baseline values and remained unchanged seven to ten days later. There were no significant differences between mucus velocities of the right and the left bronchi at any time during the experiment. Bard vs Aero-Flo Catheters

Compared to the baseline and the nonsuctioned bronchus values, there was a significant fall in bronchial mucus velocity at the end of suctioning and at 6 and 24 hours after initiating suctioning when the Bard side end-hole catheter was employed ( P <

15

20

25

RIGHT BRONCHUS - MUCOUS VELOCITY mm/min FIGURE 2. Identify plot of bronchial mucus velocity in right and left bronchi in sheep before tracheostomy.

0.001) (Table 2; Fig 3). The maximal fall of 62 percent occurred immediately after suctioning, but mucous velocity remained 40 percent lower than baseline at 24 hours. The Aero-Flo catheter was associated with a 34 percent fall in mucus velocity immediately after suctioning and with a 29 percent fall three hours later (P < 0.05) (Table 2; Fig 3). Twenty-four hours after initiating suctioning, bronchial mucus velocity had returned to values before suctioning. Mucus velocity of the bronchus not being suctioned was not affected by suctioning in the contralateral bronchus. Since minor variations of mucus velocity occurred in the control bronchus, the values of the suctioned bronchus were normalized to the nonsuctioned bronchus. This was accomplished by assum-

Table 2-Bronehial Muew J'eloeity a/ter Suetionin« Bronchial Mucus Velocity, mm/min• Group Experiment 2** Aero-Flo catheter Control bronchus Suctioned bronchus Bard side end-hole catheter Control bronchus Suctioned bronchus Experiment 3§ Aero-Flo catheter Control bronchus Suctioned bronchus Tri-Flo catheter Control bronchus Suctioned bronchus

0 hr

3 hr

6 hr

24 hr

14.3±5.1 13.1 ±4.0

13.3±5.9 8.7±3.8t

13.2±4.6 9.3 ±3.9t

14.5±3.7 12.5±3.2

15.0±4.2 15.9±4.3

14.3±3.9 6.0±2.7t

13.3±4.5 6.9±2.7t

14.2±3.8 9.6H.4t

13.2 ±2.3 14.6±1.9

12.3±3.2 11 .4±3.2t

15.6±4.5 14.5±4.9

15.0±2.8 14.6±4.8

13.1 ±3.0 7.6±2.4t

14.6±3.8 11.5±0.8

*Mean ± SD. Times are hours after starting auctioning. **Eight sheep. tP <0.05, compared to baseline.

204 LANDA ET AL

tP<0.001, eompared to baseline. §Five sheep.

CHEST, 77: 2, FEBRUARY, 1980

lAID SIDE END-HOLE

AERO-FLO TIP CATHETER

15

\

\-r--

_....

15

'\

Control lronchuo - - Sudioned lronchuo

4'

•

~ -

i

........ 3

Time (hours)

Sudioned lronchuo

;~ 24

I

6 Time (houn)

FIGURE 3. Changes in bronchial mucus velocity produced by suctioning with Aero-Flo and Bard side end-hole suctioning catheters at 3, 6, and 24 hours. Values depicted are mean± SD.

ing that the nonsuctioned bronchus was related to the suctioned bronchus by multiplying the bronchial mucus velocity of the suctioned bronchus at a given time by the product of the bronchial mucus velocity of the nonsuctioned bronchus over the baseline value of bronchial mucus velocity of the nonsuctioned bronchus. The data thus obtained are shown in Figure 4. At all points of measurement after suctioning, the depressant effect on bronchial mucus velocity associated with the Aero-Flo catheter was significantly less than with the Bard side endhole catheter ( P < 0.05). Tri-Flo vs Aero-Flo Catheters

Compared to the baseline values, there were significant falls in bronchial mucus velocity of 48 percent for the Tri-Flo catheter and of 22 percent for the Aero-Flo catheter at the end of the six-hour suctioning period ( P < 0.05) (Table 2). There was a return to baseline for both catheters 24 hours after initiating suctiooing. Normalizing the values of mucus velocity to the nonsuctioned bronchus as de-

scribed herein revealed that the Aero-Flo catheter had a less depressant effect on mucus transport at six hours compared to the Tri-Flo catheter (P < 0.05) (Fig5). DISCUSSION

Various types of tracheostomy cannulae have been used in sheep. 11 We used a fenestrated tracheostomy tube that could be occluded while not making measurements, so that the animal could breathe through the nasopharynx. The main purpose of tracheostomy was to facilitate access to the tracheobronchial tree of the sheep during suctiooing. lt also avoided the potential effects of suctioning attempts producing irritation of the nasal mucosa and larynx, which might affect bronchial mucus velocity. Another advantage of using a fenestrated tracheostomy tube is that it avoids the deleterious effects of low humidity, which injures the tracheal mucosa. Extensive histologic studies of the deleterious effects of tracheostomy on the tracheal mucosa have

15

15

..

:t' 0

. c'i

~

10

.. ...... :I

0

:I

~

..

.] -

Allo-R.O TIP

--lAID SIDE END-HOU

0 ~--r---r-----------------------, 3 6 Time (hours)

FiGURE 4. Changes in bronchial mucus velocity produced by Aero-Flo catheter, compared to Bard side end-hole catheter. Values for suctioned bronchus are normalized to nonsuctioned bronchus. CH~ST,

77: 2, FEBRUARY, 1980

..11:.

.;"

E

.!

5 -

AERO-FLO TIP

-

TRI FLO UP

0 ~-------.-------------------------------, 6

24

Time (hours)

FIGURE 5. Changes in bronchial mu<:ous velocity produ<.-ed by Aero-Flo catheter, compared to Tri-Flo catheter. Values for suctioned bronchus are normalized to nonsuctioned bronchus.

EFFECTS OF SUCTIONING ON MUCOCIUARY TRANSPORT 205

been obtained in subjects requiring therapy with mechanical ventilation and have focused primarily on morphologic considerations, representing, in fact, the results of cuff inflation and pressures required to maintain a seal with appropriate ventilation. 1•12-14 We measured bronchial mucus velocity to determine the functional consequences of tracheostomy in airways distal to the site of surgery. Bronchial mucus velocity decreased to 38 percent of baseline values at three hours, returned to baseline by 24 hours and remained near baseline one week to ten days iater (Table 1). This decrease might have been related to disruption of normal patterns of transport as a result of the surgical incision or the aspiration of small amounts of blood which may have occurred during surgery. In order to minimize the latter possibility, the cuff was inflated with a minimal amount of air ( 2to 3 ml) and was left inflated for one hour to prevent further aspiration of blood immediately after the tube had been inserted. Sackner et al4 found a decrease of 26 percent in tracheal mucus velocity in anesthetized dogs one hour after inflation of the cuff. These investigators• attributed the slowing to damming of mucus or possibly to a neurogenic reflex due to mechanical contact. Therefore, part of the fall in bronchial mucus velocity which transiently occurred after tracheostomy might have been due to pressure on the tracheal walls by the inflated cuff. The effects of tracheostomy itself are transient and do not play a long-term role in the depression of mucus transport. In 1956, Plum and Dunning 15 reported that uninterrupted vacuum during tracheobronchial suctioning might lead to severe mucosal trauma. Amikam et al7 conducted a prospective fiberoptic bronchoscopic study of tracheobronchial damage associated with prolonged endotracheal intubation and reported areas of hemorrhage and erosion distal to the tip of the endotracheal tube in both the trachea and right bronchus within hours of intubation. Since straight suctioning catheters invariably enter the right bronchus, 18 Amikam et al7 concluded that the location of lesions was consistent with damage by the suctioning catheter, as reported by Plum and Dunning. 111 In 1973, Sackner et al8 investigated the pathogenesis and prevention of these previously reported mucosal hemorrhages and erosions. Interrupted suctioning was applied to the tracheobronchial tree of anesthetized dogs using conventional, commercially available side end-hole catheters and a newly designed Aero-Flo suctioning catheter. Histologic examination of the tracheobronchial mucosa of the animals suctioned with conventional side endhole catheters showed varying degrees of mucosal denudation and edema of the lamina propria, extra208 LANDA ET AL

vasation of red blood cells, and dense infiltration with polymorphonuclear leukocytes and lymphocytes. In areas where the mucosa was completely denuded, inflammatory exudate covered the surface. In contrast, the tracheobronchial tree of dogs suctioned with the Aero-Flo catheter showed only minimal or no histologic abnormalities. In the present study, three hours of interrupted suctioning resulted in a 62 percent fall in bronchial mucus velocity at the end of suctioning in the animals suctioned with the Bard side end-hole catheter. In contrast, in animals in which the AeroFlo catheter was used, bronchial mucus velocity decreased only by 35 percent. By 24 hours, bronchial mucus velocity had returned to baseline values in the animals with Aero-Flo suctioning but remained 40 percent below baseline for animals suctioned with the Bard side end-hole catheter. These findings are in agreement with the fiberoptic bronchoscopic and histologic observations, suggesting that conventional side end-hole catheters are more damaging to the mucosa than the Aero-Flo catheter.8 More recently, Link and associates 17 reported that the Tri-Flo tip appeared to invaginate the mucosa less frequently than conventional side end-hole catheters and that damage was associated with introduction of the catheter and not with the application of vacuum. Unpublished fiberoptic bronchoscopic observations from our laboratory have failed to confirm this observation. The Tri-Flo catheter placed in the bronchi of anesthetized dogs produces erosion and edema of the mucosa by invagination of the mucosa when vacuum is applied similar to other catheters tested. 8 In the present study, we compared the effects of suctioning with the Aero-Flo catheter to the Tri-Flo catheter on bronchial mucus velocity. After six hours of interrupted suctioning, the Tri-Flo catheter produced a significantly greater reduction in bronchial mucus velocity than the Aero-Flo catheter but less reduction than the Bard side end-hole catheter (Fig 5). These studies using mucus transport as an index of injury indicate that in rank order of safety, the Aero-Flo catheter is optimal, followed by the TriFlo and the Bard side end-hole catheters. Other considerations such as ease of introduction in patients not intubated or tracheostomized should also be considered. In this respect, it is conceivable that some difficulty could· be found during introduction of the Aero Flo catheter due to its expanded tip, but in our experience in patients, this has not been a problem. These studies indicate that suctioning catheters must be designed to minimize invagination of mucosa by the holes of the catheters, in order to prevent injury to the mucosa and depression of muCHEST, 77: 2, FEBRUARY, 1980

cus transport. The restoration of mucus transport 24 hours after cessation of suctioning with the AeroFlo and Tri-Flo catheters is consistent with the finding that regeneration of ciliated epithelium begins within this time. 18

I Lindholm CE: Prolonged endotracheal intubation. Acta

Anaesthesiol Scand (Suppl) 33:10-26, 1969 2 Hilding AC, Hilding JA: Tolerance of the respiratory mucus membrane to trauma: Surgical swabs and intratracheal tubes. Ann Otol Rhinol Laryngol 71 :455-479, 1962 3 Saclmer MA, Landa JF, Greeneltch D, et al: Pathogenesis and prevention of tracheobronchial damage with suction procedures. Chest 64:284-290, 1973 4 Saclmer MA, Hirsch J. Epstein S: Effect of cuffed endotracheal tubes on tracheal mucus velocity. Chest 68:774777, 1975 5 Hilding AC: Experimental bronchoscopy in calves: Injury and repair of tracheobronchial epithelium after pas5age of bronchoscope. Am Rev Respir Dis 98:646-652, 1968 6 Hilding AC: Experimental bronchoscopy: Resultant trauma to tracheobronchial epithelium in calves from routine inspection. Trans Am Acad Ophthalmol Otolaryngol 72:604-613, 1968 7 Amikam B, Landa JF, West J, et al: Broncho6berscopic observations of the tracheobronchial tree during intuba-

tion. Am Rev Respir Dis 105:747-755, 1972 8 Friedman M, Stott FD, Poole DO, et al: A new roentgenographic method for estimating mucus velocity in airways. Am Rev Respir Dis II5 :67-72, 1977 9 Winer BJ: Statistical Principles in Experiment Design. New York, McGraw-Hill Book Co, 1971 10 Steel R, Torrie J: Principles and Procedures of Statistics. New York, McGraw-Hill Book Co, 1960 II Hecker JF: Experimental Surgery on Small Ruminants. Toronto, Butterworth and Co, 1974 12 Ioannou J: Sequelles de tracheotomie. Rev Fr Malad Respir 2:557-564, 1974 13 Andrews MJ, Pearson FG: Incidence and pathogenesis of tracheal injury following cuffed tube tracheotomy with assisted ventilation. Ann Surg 173:249-263, 1971 14 Grillo MC: Obstructive lesions of the trachea. Ann Otol Rhinol Laryngol82:770-778, 1973 15 Plum F, Dunning MF: Techniques for minimizing trauma to the tracheobronchial tree after tracheostomy. N Engl J Med 254:193-200, 1956 16 Kirimli B, King JF, FfaefHe HH : Evaluation of tracheobronchial suctioning techniques. J Thorac Cardiovasc Surg 59:340-344, 1970 17 Link WJ, Spaeth EF, Wahle WM, et al: The Influence of suction catheter tip design on tracheobronchial trauma and fluid aspiration efficiency. Anesth Analg (Cleveland) 55:290-297, 1976 18 Hilding AC: Regeneration of respiratory epithelium following minimal surface trauma. Ann Otol 74: 903-914, 1965

Plan to attend the INTERNATIONAL CONFERENCE ON BYSSINOSIS April14-16, 1980 Birmingham Hyatt House Binningham, Alabama Scientific Program Chairmen: Hans Weill, M.D., FCCP Richard Schilling, M.D. For further information, please contact Department of Education, AMERICAN COLLEGE OF CHEST PHYSICIANS, 911 Busse Highway, Park Ridge, IL 60068 (312) 698-2200

CHEST, 77: 2, FEBRUARY, 1980

EFFECTS OF SUCTIONING ON MUCOCIUARY TRANSPORT 207