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ORIGINAL ARTICLE |
Regional Department of Thoracic Surgery, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham, UK
Richard S Steyn, FRCSEd(CTh), Tel: +44 121 424 2562, Fax: +44 121 424 0562, Email: richard{at}steyn.org.uk, Regional Department of Thoracic Surgery, Birmingham Hertlands Hospital, Bordesley Green East, Birmingham B9 5SS, United Kingdom.
ABSTRACT
Various investigators have addressed the minimum lung function required to activate breathalyzers, and the impact of comorbid respiratory illness. We postulated that subjects with significant chest trauma may have difficulty in providing an adequate breathalyzer sample. A prospective self-controlled study of 20 patients who underwent thoracotomy was conducted between August 2005 and December 2005, using a Lion Alcometer SD-400. The mean age of the patients was 69.3 years (range, 37–83 years). Preoperatively, their mean forced expiratory volume was 1.97 L (range, 1.19–2.46 L), and peak expiratory flow rate was 240 L min–1 (range, 126–520 L min–1). Postoperatively, mean forced expiratory volume was 1.14 L (range, 0.34–2.2 L) and peak expiratory flow rate was 179 L min–1 (range, 36–492 L min–1). These decreases were highly significant. All patients activated the breathalyzer device preoperatively, but only 2 (10%) could activate it postoperatively. Extrapolating this to patients with chest injury, most may find it impossible to activate breathalyzers.
Key Words: Alcohol Drinking • Breath Tests • Thoracic Injuries • Thoracic Surgery
INTRODUCTION
British police have been using roadside alcohol testing since 1967, and it is now mandatory in drivers stopped with a suspicion of drinking.1 As with many other police forces, they also screen drivers involved in collisions. Drivers are initially tested with a breathalyzer at the roadside.2 If positive, evidential breath testing is performed again at a police station. Various investigators have addressed the impact of comorbid respiratory illnesses and the minimum lung function required to activate various breathalyzers.3–5 It is accepted that chronic obstructive pulmonary disease may cause difficulty in undertaking such tests, and that forced expiratory volume in the 1st second (FEV1) and forced vital capacity (FVC) are the most reliable indicators. Significant chest trauma may also cause difficulty in providing a breath sample. This depends on the significance and severity of the injury. This study was conducted to determine whether a breathalyzer can be activated by a person with significant chest trauma. Patients who had undergone thoracic surgery were used as models of chest trauma due to vehicle collision.
PATIENTS AND METHODS
A prospective self-controlled study was performed in 20 patients who underwent thoracic surgical procedures in Birmingham Heartlands Hospital between August and December 2005. Ethics committee approval was obtained, and the patients were counseled and consented into the study. Thoracotomy with lung resection was used as a model of rib fractures with pulmonary contusion, and sternotomy was used as a model of sternal fracture. We excluded patients who could not activate the breathalyzer preoperatively and those with a tracheostomy or tracheal problems who could not use the device. The mean age was 69.3 years (range, 37–83 years), and 17 (85%) patients were male. All underwent spirometry to assess lung function, as part of their preoperative assessment. Operative procedures are listed in Table 1
. A median sternotomy was performed in 1 patient, and the others underwent a posterolateral thoracotomy. All patients had general anesthesia and double-lumen endotracheal intubation with single-lung anesthesia. They were extubated on the operating table, and transferred to the thoracic high-dependency unit.
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). We investigated patients’ ability to activate the device without alcohol (dry activation). Preoperatively, patients were briefed about the device and its function, and it was used according to the manufacturer’s instructions.6 The Alcometer was calibrated, and a disposable mouth piece was attached. The patient was asked to take a deep breath in, and exhale into the device through the mouth. When the device is activated, there is a change of indicator color from red to green. The best of 3 attempts was taken into consideration. Inability to activate the device after 3 attempts was accepted as failure. This procedure was repeated on the 2nd postoperative day. We ensured that patients had adequate analgesia and the evaluation was performed after they had recovered from physiotherapy exercises. We felt this was equivalent to a chest trauma patient receiving morphine for analgesia. The spirometry was repeated on this occasion, and recorded.
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RESULTS
Preoperatively, the mean FEV1 was 1.97 L (range, 1.19–2.46 L), and mean PEFR was 240 L min–1 (range, 126–520 L min–1). Thoracic epidural pain relief was used in 12 patients, and 8 had intrathecal morphine followed by morphine infusion. After surgery, there was a decrease in both FEV1 and PEFR, irrespective of the surgical procedure (Figure 2). Postoperatively, the mean FEV1 was 1.14 L (range, 0.34–2.2 L) and PEFR was 179 L min–1 (range, 36–492 L min–1). The decreases in FEV1 and PEFR in the postoperative period were both highly significant (p = 0.000). All patients were able to activate the device preoperatively, but only 2 (10%) could activate it postoperatively; these 2 patients were males who had undergone decortication.
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Various studies have investigated the impact of lung function on ability to activate a breathalyzer. FEV1 is a significant indicator of ability to activate a breathalyzer, but the threshold value may vary with the type of device. Briggs and colleagues3 suggested that subjects with FEV1 < 1.5 L or FEV1 < 50% of predicted were unlikely to activate the Alcometer. Another study suggested higher minimum values, showing that subjects with FEV1 < 2 L and FVC < 2.6 L were unable to use any device.4 More recently, Honeybourne and colleagues5 reported continuing difficulties in the ability of some subjects to use the Lion Intoxilyser 6000 breath alcohol device, which is the model used by police in the UK, in a study attempting to validate this device in patients with chronic lung disease. The device usually requires a minimum sample volume of 1.2 L, with flow rate maintained >12 L min–1. A Canadian study on the device used by Ontario police indicated that all patients with FVC > 1.43 L could perform the test, whereas 75% of those with FVC < 1 L caused by airway obstruction were unable to provide an adequate sample.7 These findings highlight the need for adequate lung function to maintain a steady airflow through the device to activate it.
Anyone who fails to provide an adequate breath sample for alcohol testing may be charged with refusing to supply a sample, unless he convinces the police officer that he is genuinely unable to do so.4 Rib fractures, pain, pulmonary contusions, and impaired diaphragmatic movement all contribute to diminished lung function after chest injuries. Ventilatory capacity (FEV1) and vital capacity are reduced, and the residual volume is increased after chest injury.8 In a study using mathematical models, it was shown that failure to achieve full inspiration reduces the breath alcohol content at full exhalation, and reduced inhaled volume and can lead to inability to provide an adequate breath volume.9 It also demonstrated that alcohol exchange within the airways during the single-exhalation breath test is dependent on lung size. This may lead to bias against people with smaller lung size.9
We postulated that patients with significant chest injuries would not be able activate the breath analysis device due to pain and compromised respiratory function. In testing this hypothesis on patients undergoing thoracic surgical procedures, we chose the 2nd postoperative day because they were on patient-controlled morphine analgesia rather than epidural or intrathecal morphine, which are not comparable to the morphine analgesia provided by pre-hospital care practitioners or accident and emergency departments. Their decrease in lung function highlights the importance of pain and loss of chest wall mechanics in a postoperative or post-chest injury patient, in spite of adequate analgesia. Thoracic operations are a form of controlled trauma, but chest injuries in road accidents may be associated with brain concussion and other injuries, shock, and fear. A limitation of this study is that the mean age of the patients is probably higher than that of motorists driving under the influence of alcohol. Further studies may be needed in a younger cohort.
Extrapolating these findings in patients who had chest surgery, we can assume that presently available devices are difficult to activate by drivers who suffer chest trauma. This group require alternative methods to estimate alcohol levels.
ACKNOWLEDGMENTS
The Lion Alcometer SD-400 was provided by Lion Laboratories.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:282-284
© 2009 by SAGE Publications
DOI: 10.1177/0218492309104774
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