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Eur J Cardiothorac Surg 2006;29:867-872
© 2006 Elsevier Science NL
a Division of Thoracic and Hyperbaric Surgery, University Medical School, Auenbruggerplatz 29, A-8036 Graz, Austria
b University of Technology, Institute of Medical Engineering, Graz, Austria
Received 5 February 2006; received in revised form 6 March 2006; accepted 13 March 2006.
* Corresponding author. Tel.: +43 316 385 3302; fax: +43 316 385 4679. (Email: udo{at}anegg.net).
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Abstract |
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 Top Abstract 1. Introduction2. Patients and methods3. Results4. CommentReferences |
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Key Words: Airflowmetry • Pulmonary air-leaks • Pneumothorax
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1. Introduction |
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TopAbstract1. Introduction2. Patients and methods3. Results4. CommentReferences |
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Currently there is little consensus on the management of the latter. Published treatment modalities [4–6] including change of the degree of suction, placement of additional chest tubes, or re-drainage, chemical pleurodesis or even re-operation [4,7] are usually based on a semi-quantitative measurement or on only approximate assessment of air-loss through drainages by mere inspection. Because of the lack of objective data on air-loss across the lung surface ‘tentative treatments’ often precede the adequate one.
A quantification of the air leak might help to develop treatment algorithms and to define the correct moment for drain removal, thereby reducing morbidity and treatment costs.
The intention of this project was to develop a safe, reproducible and clinically applicable system providing a digital bed-side quantification of postoperative air-leaks. The device was designed to be connected in-line with the chest tube. In our patients suction drainage systems of the Buelau-type were used.
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2. Patients and methods |
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TopAbstract1. Introduction2. Patients and methods3. Results4. CommentReferences |
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After lung resection air-leaks on the lung surface were pinpointed by rinsing the lung with warm saline solution during ventilation at a maximum inspiratory pressure of 25 cmH2O. Leaks scored as grade 3 (coalescent bubbles) were sutured with pledget-reinforced PDS 3-0 sutures (Johnson & Johnson, Ethicon, Hamburg, Germany) and reduced to at least grade 2 (stream of bubbles). Grade 2 leakages were covered with a collagen fleece coated with fibrinogen and thrombin coagulation factors (TachoSil® Nycomed, Langebjerg, Rokskilde, Denmark), whereas grade 1 leakage (single bubbles) were mostly left to heal spontaneously.
Intraoperative quantitative spirometry was performed in all patients. The pleural cavity was closed when macroscopic leakage of no more than grade 1 or 2 was present, corresponding to less than 250 ml spirometric air-loss per tidal volume.
In patients who underwent lobectomy two chest tubes were placed, one of which was removed on the first or second postoperative day, in patients who underwent wedge resection only one tube was inserted. In all cases –12 cm continuous suction was applied by using a drainage system of the Buelau-type.
The routine procedure for air-leaks used at our division was performed in all patients: –12 cm continuous suction was applied until removal of the chest tubes, provided that the initial degree of air-loss was found to continuously diminish or subside, respectively, during the first three postoperative days. If the air-loss persisted unchanged beyond the 3rd day, a Heimlich valve was connected distally to the fluid catchment tank of the system (Fig. 1 ). If the lung remained expanded on chest-roentgenograms or if a small, stable, asymptomatic pneumothorax developed, the valve was left in place until removal of the drainage. In case of an enlarging pneumothorax or in presence of dyspnea –12 cm suction was re-established and left until the air-leak gradually subsided and disappeared or until a decision for redo-operation was made. In each patient a control chest-roentgenogram was done on the day after removal of the last drainage.
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Following each measurement the data acquired can be printed in an ‘airflowmetry report’ to be stored with the documents of the respective patient.
2.2 Assessment of air-leakage
In each patient the presence or absence of a leakage was crudely assessed by watching the chest tubes for the passage of bubbles.
The definitive amount of leakage was displayed and recorded as ml leakage per breath (ml/b) and ml leakage per minute (ml/min).
The first measurements were scheduled on the first and on the third postoperative days. If the air-leak diminished the next measurement was done when there was no more visually detectable air-loss over the drainage. If in these cases the measurements showed no more leakage the drainage was removed, if not, daily measurements were continued until the air-leak had subsided. In cases with fistulae persisting unchanged beyond the third postoperative day regular measurements were scheduled on a daily basis. The latter were continued until the leakage diminished to less than the agreed threshold value or until re-operation.
The degree of suction during the measurements followed a standard protocol which included –20 cmH2O, –12 cmH2O and Heimlich valve on the first postoperative day and –12 cmH2O and Heimlich valve during the following measurements. The patients were asked to breathe normally, to take deep breaths, to cough and to breathe out against the resistance of a flutter valve. As standard parameters, the leakage per expiration as well as the leakage per minute were displayed and recorded on the computer.
Removal of the chest tubes was done when the air-leakage volume was less than 20 ml/min or less than 1, 0 ml/b during normal breathing on Heimlich valve, this amount of air-loss being considered due to shifts in the measuring system itself. The threshold of fluid-drainage volume over the chest-drain considered apt for removal was 250 ml/24 h.
2.3 Validation of the system
Immediately after closure of the chest the AIRFIX® device was connected to the drainage system as described above. The air-leak displayed by the AIRFIX® device was compared with the one shown during simultaneous intraoperative spirometry.
Daily chest-roentgenograms were taken until no further leakage could be measured. A control roentgenogram was done after removal of the last chest tube.
2.4 Statistics
Statistical analysis was performed by utilizing Student's t-test for paired values.
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3. Results |
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TopAbstract1. Introduction2. Patients and methods3. Results4. CommentReferences |
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A total of 7296 measurements was performed (mean: 35.76/patient, range: 28–92). The digital bed-side airflowmetry of chest tubes was performed without any complications. A measurement series (8 or 12 measurements, respectively) took 10–15 min. Depending on the suction level and the type of breathing manoeuvre air-leaks within the range of 0.25–45 ml/b or 5–900 ml/min were documented (Table 1 ). All single measurements of each patient were stored as airflow-report in the patient's records.
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Coughing in presence of a Heimlich valve resulted in insignificantly higher air-leakage than normal breathing while applying a suction level of –20 cm (p > 0.05).
In 26 out of 174 patients in whom air leakage was no longer visually detectable within 2–5 days airflowmetry showed minor, but still measurable air-loss that lasted up to 7 days. Based upon the measurements the decision for chest tube removal was postponed accordingly. In 31 patients an air-leak was measurable beyond the 7th postoperative day. In these latter patients the time of drainage based upon the measurements was between 9 and 24 days. In four of them redo-thoracotomy was done 10–13 days postoperatively. In these four cases no change whatsoever of leakage rates on –12 cm suction was found throughout the postoperative course (mean leakage rates on normal breathing: 227, 235, 247, 260 ml/min). When set on the Heimlich valve the leakage persisted at a lower level (leakage rates: 83, 86, 91, and 92 ml/min, respectively), while an expanding pneumothorax and dyspnea developed shortly after connecting the valve. On re-thoracotomy in each of the four cases a small broncho-pleural fistula was identified and closed by pledget-reinforced PDS 3-0 sutures. The further course was uneventful.
No problems whatsoever resulted from the temporary changes in suction level required during the measurement periods or from the intermittent in-line connection of the system to the chest-drain.
None of the patients required re-drainage due to recurrent pneumothorax after drain removal.
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4. Comment |
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TopAbstract1. Introduction2. Patients and methods3. Results4. CommentReferences |
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Countless surgical attempts to prevent any air leak in the first place have proved that the lung surface cannot always be sufficiently sealed. A randomized multicentre study performed by Wain et al. [9] showed intraoperative air-leaks in more than 70% of patients who had undergone pulmonary resections using standard techniques for closure of lung parenchyma.
In the postoperative course of a bronchopleural fistula the decision whether to set chest tubes on different suction levels, on water seal or on Heimlich valve is a crucial one.
In fact, the surgeon's subjective estimation and not precise reproducible data [5] commonly determine the procedure. In this context, Cerfolio et al. [4–6] suggested the use of clear-cut algorithms for the treatment of air-leaks. In a first attempt air-leaks were detected on the basis of bubble-formation by putting the end of a Heimlich valve into a tank of water during forceful breathing or coughing. In another setting a semi-quantitative assessment was accomplished by the use of a commercially available air-leak meter integrated into a chest drainage system (Sahara Pleur-evac, Deknatel, Boston, MA, USA): the meter scores leaks from 1 to 7 with 7 being the highest. By taking several deep breaths bubbles become visible in the drainage system, where they move into one of seven chambers. The larger the leak the more chambers the bubbles move into. However, the main shortcomings of this method are its dependence on subjective interpretation of the course of bubbles and the impossibility to record, store or reproduce the test results. The problem of an enlarging pneumothorax after the reduction of the suction or after drain removal based upon these measurements still persists [4–6].
A clear-cut quantification of the air-loss from the lung surface may help to both establish and validate algorithms for management of postoperative bronchopleural fistulae and enable an exact determination of the correct time for drain removal.
In the present study, a newly developed tool for quantification of postoperative air-leaks was evaluated in patients all of whom had air-leaks on the lung surface at the end of the operation. The system was easily applicable in everyday clinical routine. No problems whatsoever emerged from the temporary changes in suction levels required for the measuring procedures. In contrast to the usual ‘visual’ assessment of air-leaks by bubbles moving through chest drains or into specially designed ‘chambers’ the new system also permits a quantification of the netto-air-loss, subtracting air shifts out of and into dead pleural space – a phenomenon often encountered after lobectomies [10].
Using the AIRFIX® device the influence of different breathing manoeuvres and of increased expiratory resistance as well as the influence of different suction algorithms (–20, –12 cm and Heimlich) on postoperative air leak could be demonstrated very clearly and reproducibly, underlining the fact that in cases of minor air-leak a reduction of the degree of negative intrapleural pressure will enhance healing of the fistula in most cases.
On the other hand, air-leaks were detected in cases presumed to have none by visual assessment. It cannot be stated whether or not clamping or removal of the drainage based upon visual assessment would have been ensued by enlarging pneumothorax and/or the necessity for re-drainage in these patients. When the decision for chest-tube removal was based upon strict criteria derived from the measurements, however, re-drainage was not mandatory in any patient.
A further benefit of the system is the possibility of electronical storage of the data with the option of a printout, permitting repeated objective comparative evaluations in the course.
In this study, daily chest-roentgenograms were performed in order to early diagnose a pneumothorax in the context of the setting. Our initial experience with the measuring device suggests a high degree of reliability, which may reduce the need for control chest-roentgenograms. A further reduction of costs and of discomfort for the patient may derive from the fact that the measuring system may obviate the need for tentative clamping and may thus enable an earlier discharge from hospital.
In conclusion, the AIRFIX® device fulfils many requirements for the introduction of an evidence-based algorithm for the evaluation and treatment of air-leaks, reducing morbidity, hospitalization and treatment costs. However, further studies on this issue are necessary.
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Footnotes |
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Presented at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 12–15, 2004. |
References |
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TopAbstract1. Introduction2. Patients and methods3. Results4. CommentReferences |
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