Measurement of Mucociliary Transport Velocity in Ventilated Patients* Short-term Effect of General Anesthesia on Mucociliary Transport Franz Konrad, M.D.; Torsten Schreiber; Adolf Crimert, M.D., Ph.D.; Malte Clausen, M.D.; and Friedrich Wilhelm Ahnefeld, M.D. Objectives: The objectives of this study were to evaluate a method for measuring BlV in ventilated patients and to study the short-term effect of general anesthesia with midazolam, Fentanyl, pancuronium and O.:N.O on BlV. Daign: The study included phantom measurements on a bronchoscopy model and the determination of BlV in patients in a convenience sample trial. Setting: The study took place in a university hospital. Patients: Fourteen patients undergoing major abdominal surgery with plenaed postoperative mechanical ventilation were included in the stud~ All patients gave their written informed consent to participate in the study. lnterl'entiona: Bronchial mucus transport velocity was measured with a small volume (0.05 to 0.08 ml) of technetium 99m-labeled albumin microspheres with an activity of 3 MBq. The radiolabeled bolus was deposited on the dorsal mucosal surface at the distal end of the right and left main bronchus via 8exible bronchoscopy. The movement of the microspheres toward the trachea was visualized and recorded using a scintillation camera; quantitative evaluation utilized the condensed image. Main measurements and reaulta: The technique was validated in a bronchoscopy model and in an intubated patient
clearance is an important protective M ucociliary mechanism of the upper and lower respiratory tract. Gamsu et all reported on a possible correlation between impaired mucus transport and the postoperative development of atelectasis. At the end of the operation, those investigators insufBated Tantalum powder into the tracheobronchial system and followed its disappearance roentgenologically. They found impaired mucociliary clearance function to be significantly associated with postoperative atelectasis. Patients receiving mechanical ventilation frequently have a tendency to retain secretions. Ofall hospitalized patients, these subjects are most frequently threatened by pneumonia." To our knowledge, with the exception of a study of Lichtiger et aI,5 no investigations of mucociliary clearance in ventilated patients have been
*From the Clinics for Anesthesiology (Dr. Konrad, Mr. Schreiber and Dr. Ahnefeld) and Clinical Chemistry (Dr. Grunert), University of Ulm, Ulm (Donau), Germany; the Clinic of Nuclear Medicine (Dr. Clausen), University of Kiel, Kiel, Germany Manuscript received December 23, 1991; revision accepted April 16. Reprint requests: Dr. Konrad, Universitat fur Anesthesiologie, Klinikum der Universitat Ulm, D-7900 Ulm, Gennany
by moving a radioactive drop in a catheter through the main bronchi at velocities from 0 to 20 mmlmin. The velocities determined by the image processing technique correlated well with the data by the model and patient determination (right bronchus, r 1.0; left bronchus, r = 1.0). In seven ventilated patients, mechanical irritation by the 6berscope produced no signi6cant effect on BlV. The BlV was measured preoperatively in seven conscious patients one day before surgery while they received local anesthesia with 10 ml of 1 percent lidocaine and postoperatively while they received intubation anesthesia. The preoperative and postoperative BlV values showed DO signi6cant differences (10.5; 5.7 to 13.7 mmlmin; vs 9.7 (3.7 to 15.3) (median with range). ConcluBion: By this method, bronchial transport velocity can be determined in a relatively short time in ventilated patients. General anesthesia with midazolam, Fentanyl, pancuronium and O.:N.O does not influence BlV. (Chat 1992; 102:1311-83)
=
=
=
B1V bronchial mucus transport velocity; VJ velocity determined by image processing technique; VP = velocity by patient determination.
published. By the cinebronchofiberscopic method of Sackner et aI,6 Lichtiger et al5 determined the tracheal transport velocity in 14 female patients during gynecologic operations while they were receiving Halothane intubation anesthesia. After 90 min, mucus transport ceased almost entirely, the tracheal mucosa was reddened or edematous, and massive secretion accumulations were observed. The measurement of transport velocity in the trachea of intubated patients presents a problem. The distance of the tip of the tube from the distal end of the trachea and thus the travel distance measured can in some cases be very short. Moreover, mucus transport presumably ends at the blocked tube cuff As a result, particularly during long-term mechanical ventilation, secretions accumulate in the trachea and usually must be sucked out by regular tracheobronchial toilet.":" Because suctioninduced microlesions and secretion spots in the trachea must be expected under these conditions," reduced tracheal transport velocity does not permit conclusions to be drawn about the remaining bronchial system. The present study deals with the evaluation of a method for measuring BlV in patients receiving CHEST I 102 I 5 I NOVEMBER, 1992
1377
mechanical ventilation. To this end, the method described by Chopra et al'? was modified and the transport velocity of a radiolabeled bolus in the right and left main bronchus was measured. This method was applied clinically to investigate the effect of midazolam, Fentanyl, pancuronium and 02:N20 general anesthesia on BTv. This type of anesthesia, because of its very slight effect on cardiovascular function, frequently is used in high-risk patients and for long-lasting procedures. Whether under these conditions-as with inhalation anesthetic agents ll • 13 mucociliary clearance function is impaired has not yet been investigated. MATERIALS AND METHODS Determination of Bronchial Transport \i1locity (BTV)
The measurements were performed on patients lying in the supine position without elevating the upper part of their body. Bronchial transport velocity was determined with (-TC-MAA) with a particle diameter from 10 to 40 ....m (Maascint, Medgenix, Brussels. Belgium) . By means of a thin catheter (BC OC, Olympus; Hamburg, Germany), 0 .05 to 0.08 ml of-Tc-MAA with an activity of 3 MBq was applied under visual control through the working channel of a flexible bronchoscope (BF 1 T 10, Olympus; Hamburg, Germany), onto the mucosa of the dorsal distal right and left primary bronchus (0.5 cm above the ostium of the superior segment of the lower lobe) by an atraumatic procedure. The time required for visually controlled application of the radioactive boluses by bronchoscopy was on the average 2.5 min and at the most 3 min . This was followed for 30 min by dynamic data acquisition with a scintillation camera (Starport system; collimator: low energy general purpose, 500-mm diameter, General Electric) in the anterior position. Sixty-four images of a 64 x 64 matrix were recorded with an exposure of3O s per image. The cinematographic technique was used for qualitative data evaluation and orientation, and the quantitative evaluation was done on the condensed image." For this purpose, a ROI of the cinematographically visualized area of transport of the radioactive deposit was defined . For each row, the
~~ • 3
'~LJ
;
~~
maximum count per matrix element was determined on the first image and entered into the first column of a new matrix. This procedure was repeated for all 64 images. One column in the condensed image was assigned to each image. This path-time diagram" served as a basis for further image processing: transport processes now appear as non horizontal radioactivity streaks (Fig I). Tangents to these streaks were drawn interactively under visual control. From the slope of these stra ight lines, the known length of the picture elements (6.2 mm) and the exposure time per image (30 s), the transport velocity of the radioactive deposit in millimeters per minute can be calculated . For validation of the method used, phantom images were recorded on a plastic human anatomical model with a bronchial tree on a 1:1 scale (Scopin bronchoscopy model according to Nahkosteen CLA ; Coburg, Germany). A drop of radioactive material with an activity of 3 MBq contained in the tip of a catheter (BC 9 C , Olympus; Hamburg, Germany) was moved through the right and left primary bronchus at a velocity from 0 to 20 mm/min. The validation was performed for both primary bronchi because in intubated patients one-sided impairment of the transport function can take place (for example, after double-lumen intubation or bronchial suturing). The data acquisition and evaluation described above were done by an investigator who did not know the velocities used . The transport velocities determined by image processing were then compared with the data given by the model. Interobseroer Variability
To check for interobserver variability, the measurements performed on the model were evaluated by a second investigator who did not know the velocities used or the results obtained by the first investigator. Additional Validation in an Intubated lbtient
To strengthen the results of the model measurements, the validation with the catheter pullback was additionally carried out in a 26-yeaMlld male organ donor with the informed consent of his
wife. lbtients Studied
The study was approved by the Ethics Committee of the University of Ulm, Ulrn, Germany. All patients rece ived an expla -
2
clearance is an important protective M ucociliary mechanism of the upper and lower respiratory tract. Gamsu et all reported on a possible correlation between impaired mucus transport and the postoperative development of atelectasis. At the end of the operation, those investigators insufBated Tantalum powder into the tracheobronchial system and followed its disappearance roentgenologically. They found impaired mucociliary clearance function to be significantly associated with postoperative atelectasis. Patients receiving mechanical ventilation frequently have a tendency to retain secretions. Ofall hospitalized patients, these subjects are most frequently threatened by pneumonia." To our knowledge, with the exception of a study of Lichtiger et aI,5 no investigations of mucociliary clearance in ventilated patients have been
*From the Clinics for Anesthesiology (Dr. Konrad, Mr. Schreiber and Dr. Ahnefeld) and Clinical Chemistry (Dr. Grunert), University of Ulm, Ulm (Donau), Germany; the Clinic of Nuclear Medicine (Dr. Clausen), University of Kiel, Kiel, Germany Manuscript received December 23, 1991; revision accepted April 16. Reprint requests: Dr. Konrad, Universitat fur Anesthesiologie, Klinikum der Universitat Ulm, D-7900 Ulm, Gennany
by moving a radioactive drop in a catheter through the main bronchi at velocities from 0 to 20 mmlmin. The velocities determined by the image processing technique correlated well with the data by the model and patient determination (right bronchus, r 1.0; left bronchus, r = 1.0). In seven ventilated patients, mechanical irritation by the 6berscope produced no signi6cant effect on BlV. The BlV was measured preoperatively in seven conscious patients one day before surgery while they received local anesthesia with 10 ml of 1 percent lidocaine and postoperatively while they received intubation anesthesia. The preoperative and postoperative BlV values showed DO signi6cant differences (10.5; 5.7 to 13.7 mmlmin; vs 9.7 (3.7 to 15.3) (median with range). ConcluBion: By this method, bronchial transport velocity can be determined in a relatively short time in ventilated patients. General anesthesia with midazolam, Fentanyl, pancuronium and O.:N.O does not influence BlV. (Chat 1992; 102:1311-83)
=
=
=
B1V bronchial mucus transport velocity; VJ velocity determined by image processing technique; VP = velocity by patient determination.
published. By the cinebronchofiberscopic method of Sackner et aI,6 Lichtiger et al5 determined the tracheal transport velocity in 14 female patients during gynecologic operations while they were receiving Halothane intubation anesthesia. After 90 min, mucus transport ceased almost entirely, the tracheal mucosa was reddened or edematous, and massive secretion accumulations were observed. The measurement of transport velocity in the trachea of intubated patients presents a problem. The distance of the tip of the tube from the distal end of the trachea and thus the travel distance measured can in some cases be very short. Moreover, mucus transport presumably ends at the blocked tube cuff As a result, particularly during long-term mechanical ventilation, secretions accumulate in the trachea and usually must be sucked out by regular tracheobronchial toilet.":" Because suctioninduced microlesions and secretion spots in the trachea must be expected under these conditions," reduced tracheal transport velocity does not permit conclusions to be drawn about the remaining bronchial system. The present study deals with the evaluation of a method for measuring BlV in patients receiving CHEST I 102 I 5 I NOVEMBER, 1992
1377
mechanical ventilation. To this end, the method described by Chopra et al'? was modified and the transport velocity of a radiolabeled bolus in the right and left main bronchus was measured. This method was applied clinically to investigate the effect of midazolam, Fentanyl, pancuronium and 02:N20 general anesthesia on BTv. This type of anesthesia, because of its very slight effect on cardiovascular function, frequently is used in high-risk patients and for long-lasting procedures. Whether under these conditions-as with inhalation anesthetic agents ll • 13 mucociliary clearance function is impaired has not yet been investigated. MATERIALS AND METHODS Determination of Bronchial Transport \i1locity (BTV)
The measurements were performed on patients lying in the supine position without elevating the upper part of their body. Bronchial transport velocity was determined with (-TC-MAA) with a particle diameter from 10 to 40 ....m (Maascint, Medgenix, Brussels. Belgium) . By means of a thin catheter (BC OC, Olympus; Hamburg, Germany), 0 .05 to 0.08 ml of-Tc-MAA with an activity of 3 MBq was applied under visual control through the working channel of a flexible bronchoscope (BF 1 T 10, Olympus; Hamburg, Germany), onto the mucosa of the dorsal distal right and left primary bronchus (0.5 cm above the ostium of the superior segment of the lower lobe) by an atraumatic procedure. The time required for visually controlled application of the radioactive boluses by bronchoscopy was on the average 2.5 min and at the most 3 min . This was followed for 30 min by dynamic data acquisition with a scintillation camera (Starport system; collimator: low energy general purpose, 500-mm diameter, General Electric) in the anterior position. Sixty-four images of a 64 x 64 matrix were recorded with an exposure of3O s per image. The cinematographic technique was used for qualitative data evaluation and orientation, and the quantitative evaluation was done on the condensed image." For this purpose, a ROI of the cinematographically visualized area of transport of the radioactive deposit was defined . For each row, the
~~ • 3
'~LJ
;
~~
maximum count per matrix element was determined on the first image and entered into the first column of a new matrix. This procedure was repeated for all 64 images. One column in the condensed image was assigned to each image. This path-time diagram" served as a basis for further image processing: transport processes now appear as non horizontal radioactivity streaks (Fig I). Tangents to these streaks were drawn interactively under visual control. From the slope of these stra ight lines, the known length of the picture elements (6.2 mm) and the exposure time per image (30 s), the transport velocity of the radioactive deposit in millimeters per minute can be calculated . For validation of the method used, phantom images were recorded on a plastic human anatomical model with a bronchial tree on a 1:1 scale (Scopin bronchoscopy model according to Nahkosteen CLA ; Coburg, Germany). A drop of radioactive material with an activity of 3 MBq contained in the tip of a catheter (BC 9 C , Olympus; Hamburg, Germany) was moved through the right and left primary bronchus at a velocity from 0 to 20 mm/min. The validation was performed for both primary bronchi because in intubated patients one-sided impairment of the transport function can take place (for example, after double-lumen intubation or bronchial suturing). The data acquisition and evaluation described above were done by an investigator who did not know the velocities used . The transport velocities determined by image processing were then compared with the data given by the model. Interobseroer Variability
To check for interobserver variability, the measurements performed on the model were evaluated by a second investigator who did not know the velocities used or the results obtained by the first investigator. Additional Validation in an Intubated lbtient
To strengthen the results of the model measurements, the validation with the catheter pullback was additionally carried out in a 26-yeaMlld male organ donor with the informed consent of his
wife. lbtients Studied
The study was approved by the Ethics Committee of the University of Ulm, Ulrn, Germany. All patients rece ived an expla -
2
