The diagnostic yield and clinical impact of a chest X-ray after percutaneous dilatational tracheostomy: a prospective cohort study.
A chest X-ray (CXR) is routinely performed after percutaneous dilatational tracheostomy (PDT). The purpose of this study was to evaluate the diagnostic yield of routine CXR following PDT and its impact on patient management and to identify predictors of post-PDT CXR changes. Two-hundred-and-thirty-nine patients who underwent PDT in a 21-bed intensive care unit were included prospectively in the study. The following data were collected: patient demographics, APACHE III scores, pre-PDT Fi[O.sub.2] and PEEP, PDT technique, perioperative complications and the use of bronchoscopic guidance. We compared post-PDT CXR with the last pre-PDT CAR. We documented any post-PDT new radiographic findings including atelectasis, pneumothorax, pneumomediastinum, surgical emphysema, pulmonary infiltrates or tracheostomy tube malposition. We also recorded management modifications based on post-PDT radiographic changes, including increased PEEP, chest physiotherapy, therapeutic bronchoscopy or chest tube insertion. Atelectasis was the only new finding detected on post-PDT CXRs of 24 (10%) patients. The new radiographic findings resulted in a total of 14 modifications of management in 10 (4%) patients including increased PEEP in six, chest physiotherapy in six and bronchoscopy in two patients. Trauma and pre-PDT PEEP >5 cm[H.sub.2]O were independent predictors of post-PDT CXR changes. Routine CXR following PDT has a low diagnostic yield, detecting mainly atelectasis and leading to a change in the management in only a minority ofpatients. Routine CXR after apparently uncomplicated PDT performed by an experienced operator may not be necessary and selective use may improve its diagnostic yield. Further studies are required to validate the safety of selective versus routine post-PDT CXR.
Key Words: chest radiograph, percutaneous dilatational tracheostomy, intensive care, complications
Percutaneous dilatational tracheostomy (PDT) has become an integral part of airway management in the critical care setting and it is one of the most frequently performed procedures in critically ill patients. It has gained an increasing acceptance as an alternative to the classic operative tracheostomy and several prospective randomised trials (1-4) have reported a lower incidence of complications with PDT compared to surgical tracheostomy.
Chest X-ray (CXR) is routinely performed after PDT as a standard practice to confirm tracheostomy tube placement and to detect potentially serious complications. A few studies have been performed to determine the usefulness of routine CXR following either surgical tracheostomy (5) or PDT performed under bronchoscopic guidance (6, 7). However, PDT is also performed without bronchoscopic guidance. The yield of routine CXR after PDT performed without bronchoscopic guidance has not been examined before. Our hypothesis is that routine CXR after PDT performed without bronchoscopic guidance has a low diagnostic yield and leads to few changes in patient management. Therefore, we conducted this study to evaluate prospectively the yield of post-PDT CXR and to identify predictors of radiographic changes.
MATERIALS AND METHODS
This prospective cohort study was conducted in a 21-bed, tertiary care medical-surgical intensive care unit (ICU) in an 800-bed teaching hospital level-one trauma centre in Riyadh, Saudi Arabia. The ICU, which admits more than a thousand patients per year, is run as a closed unit 24 hours a day, seven days a week by in-house full-time Critical Care Board-certified Intensivists. The study was approved by the Institutional Board Review.
All consecutive patients older than 16 years who underwent PDT between May 2004 and December 2005 were included. An informed consent for PDT was obtained from all patients.
PDTs were performed at the bedside by intensivists with a large cumulative experience of more than two-hundred PDTs, assisted by a critical care fellow or resident. The technique of PDT was either Ciaglia "single-step dilation" (8) using the Ultraperc Percutaneous Tracheostomy Kit (Smiths, Portex company; equivalent to the Ciaglia Blue Rhino) or Griggs9 (Guide Wire Dilator Forceps: GWDF) using the Percutaneous Tracheostomy Kit (SimsPortex). All patients were sedated, pharmacologically paralysed and mechanically ventilated with 100% oxygen during the procedure. Regularly, PDT was performed without bronchoscopic guidance. However, bronchoscopy was used in selected patients such as in patients with cervical spine injury or with a short fat neck.
Pre-and post-PDT CXR
A CXR is performed, as daily routine, in the morning before PDT and another CXR is performed, as post-procedure, within the first 30 minutes following the PDT.
The following data were collected: patient demographics including age, gender, height and weight; admission categories (surgical, medical, trauma or burns); Acute Physiology and Chronic Health Evaluation III (APACHE III) scores (10); pre-PDT fraction of inspired oxygen (Fi[O.sub.2]) and positive end-expiratory pressure (PEEP); the use of bronchoscopic guidance and technique of PDT (Griggs "GWDF" or Ciaglia "single-step dilation"). We compared the post-procedure CXR with the last pre-procedure CXR and recorded any new changes including atelectasis, pneumothorax, pneumomediastinum, subcutaneous emphysema, pulmonary infiltrates, tracheostomy tube malposition, or para-tracheal tube placement. We documented modifications in management based on the post-procedure radiographic new findings including increase of PEEP, chest physiotherapy, therapeutic bronchoscopy, chest tube insertion, or tracheostomy tube repositioning.
We used Minitab for Windows (Minitab Inc., Release 12.1, State College, PA, U.S.A.) for statistical analysis. We used descriptive statistics to describe patients' baseline characteristics, post-PDT CXR changes and their impact on patient management. Continuous variables were described as mean and standard deviation (SD) and categorical variables were expressed as absolute and relative frequencies. We used univariate analysis to identify predictors of post-PDT CXR changes. Significant predictors were entered into stepwise regression to identify independent predictors of CXR changes.
Two-hundred-and-thirty-nine patients underwent PDT during the study period. The mean ([+ or -] SD) age of patients was 54 [+ or -] 22 years. Male patients totalled 185 (77.4%). The admission categories were as follows: medical 145 (61%), trauma 67 (28%), surgical 25 (10%) and burn 2 (1%). The mean ([+ or -] SD) of APACHE III score was 79 [+ or -] 29 (Table 1).
The pre-PDT Fi[O.sub.2] ([+ or -] SD), PEEP [+ or -] SD (cm[H.sub.2]O), PEEP > 5 (cm[H.sub.2]O) and Fi[O.sub.2] >0.4 were 0.33 [+ or -] 0.07, 5.8 [+ or -] 3.8, 58 (24%), and 20 (8.3%), respectively. In all, 228 patients (95.4%) underwent PDT without bronchoscopic guidance and 11 patients (4.6%) under bronchoscopic visualisation. "Single-step dilation" Ciaglia technique was used in 209 (87.5%) patients and Griggs (GWFD) technique in 30 (12.5%) patients (Table 2).
Post-PDT CXR changes and impact on management
Atelectasis was the only new change detected on the post-procedure CXR and was found in 24 (10%) patients. In the remaining 215 (90%) patients, there were no significant abnormalities detected on the post-procedure CXR. Fourteen modifications in management, based on post-procedure CXR findings, were noted in 10 (4%) patients. These modifications in management included increase of PEEP (by 3 to 5 cm[H.sub.2]O) in six (2.5%) patients, chest physiotherapy in six (2.5%) patients and therapeutic bronchoscopy in two (1%) patients.
Predictors of post procedure CXR changes
Table 3 shows the results of univariate analysis of predictors of post-procedure CXR changes. Trauma and pre-PDT PEEP >5 cm[H.sub.2]O were predictors of post-tracheostomy CXR changes (OR=4.28, 95% CI=1.80-10.20, P=0.001 and OR=3.01, 95% CI=1.27-7.15, P=0.013, respectively). However, age and medical admissions were associated with lower incidence of post-procedure CXR changes (OR=0.97 for each year of age, 95% CI=0.950.99, P=0.002; and OR=0.35, 95% CI=0.15-0.83, P=0.018, respectively). The following variables were not significantly associated with an increase or a decrease in the incidence of post-procedure CXR changes: gender, surgical reason for ICU admission, APACHE III score, pre-PDT Fi[O.sub.2] >0.4, technique of PDT, bronchoscopy use, or the occurrence of perioperative complications. Using stepwise regression of predictors of post-procedure CXR changes, only trauma and pre-PDT PEEP >5 cm[H.sub.2]O remained as significant independent predictors of CXR changes (Table 4). The incidence of post-procedure CXR changes was 3% in non-trauma patients receiving PEEP [less than or equal to] 5 cm[H.sub.2]O, 14% in non-trauma patients receiving PEEP >5 cm[H.sub.2]O, 18% in trauma patients receiving PEEP > 5 cm[H.sub.2]O, and 29% in trauma patients receiving PEEP >5 cm[H.sub.2]O (P<0.001).
The main findings of this prospective study are that a) the diagnostic yield of routine CXR following PDT performed without bronchoscopic guidance is low; b) atelectasis is the main change detected on the post-PDT CXR; c) trauma and pre-PDT PEEP >5 cm[H.sub.2]O are independent predictors of post-tracheostomy CXR changes; and d) the post-PDT CXR leads to modification of management in a small number of patients.
The incidence of perioperative complications with PDT has ranged in different studies from 3 to 18% (11-16). Several tools have been suggested to minimise the incidence and severity of complications and to improve the safety of PDT such as bronchoscopic guidance and post-procedure CXR. Studies have demonstrated that bronchoscopic monitoring during PDT facilitates the procedure and reduces potential complications, hence providing a higher degree of safety (16-22). However, bronchoscopic guidance is not always necessary and a growing body of literature supports the safety of performing PDT without bronchoscopic guidance (11, 23-6). Studies reported no significant differences in the incidence of complications of PDT performed with or without bronchoscopy (11).
The complications that would be detected on the post-procedure CXR following PDT include atelectasis, pneumothorax, pneumomediastinum, pulmonary infiltrates, tracheostomy tube mal-positioning and paratracheal tube placement. However, recently, the value of routine post-tracheostomy CXR has been challenged as well as its impact on patient management.
Few studies have examined the value of routine post-procedure CXR following PDT performed under bronchoscopic guidance. Datta et al (6), in a retrospective study, examined the usefulness of routine CXR following PDT performed under bronchoscopic visualisation. In two (3.3%) of the 60 patients, postoperative complications were detected on the post-procedure CXR, one with a pneumomediastinum that was treated conservatively and the other with a tension pneumothorax that was treated with a chest tube insertion. In both cases, the PDT procedure was noted to be difficult, with a high physician anticipation of complications. However, it is unclear whether the investigators examined procedure difficulty systematically for all patients or only for those who had CXR changes. The authors concluded that CXR is not necessary after PDT if performed under bronchoscopic guidance unless there is procedural difficulty. The retrospective nature and the small number of patients make the conclusion difficult to generalise. In contrast to the findings of Datta, our study did not show that bronchoscopic guidance during PDT reduces the incidence of CXR changes, or that there is an association between perioperative complications and occurrence of post-PDT CXR changes. Based on the above, the decision to perform CXR after PDT cannot be made on whether bronchoscopy was used or not, nor on whether the PDT procedure was difficult or not.
Recently, Hoehne et all', in a retrospective study of 73 patients, evaluated the utility of CXR after PDT performed with bronchoscopic guidance. The study detected no complication on the post-PDT CXR in the 73 patients. Again, the retrospective nature and the small number of patients might have underestimated the incidence of post-PDT CXR changes.
Nevertheless, it is important to note that serious and life-threatening complications of PDT such as paratracheal tube placement are usually self-evident and should be recognised clinically and managed instantly prior to a CXR being performed. Consequently, CXR is not the standard tool for the diagnosis of such life-threatening complications. Conversely, other complications such as atelectasis are of less clinical significance and delayed diagnosis until the next-day CXR might not have a major consequence.
Our study advances the clinical management of the post-PDT patients in important ways, as well as complementing current literature. Along with other studies, it demonstrated that routine CXR following tracheostomy, whether surgical (5) or PDT performed with (6, 27) or without bronchoscopic guidance, is probably unnecessary and selective use may be more appropriate. The question is what are the criteria to perform a CXR after tracheostomy? Our study provided some clues to such a decision. In trauma patients, trauma was the most significant predictor of CXR changes after PDT This finding may be explained by the fact that trauma patients who require tracheostomy are at high risk of developing respiratory complications for several reasons including loss of ability to clear the bronchial tree (intense analgesia and sedation) leading to retention of secretions and formation of mucous plugs with resultant atelectasis. Moreover, trauma has been identified as an independent risk factor for the development of nosocomial pneumonia (28, 29). We also found that PEEP >5 cm[H.sub.2]O was also a significant predictor of CXR changes after PDT This is probably related to alveolar collapse and derecruitment due to the loss of PEEP after tracheal opening and dilatation.
This study has a number of strengths including the prospective nature, the inclusion of all consecutive patients and the large number of patients. As a potential limitation, the study was observational and was conducted in a single centre.
Post-procedure CXR following PDT performed without bronchoscopic guidance has a low diagnostic yield, detecting mainly atelectasis and leading to a change in the management in a minority of patients. Routine CXR after apparently uncomplicated PDT performed by an experienced operator may not be necessary and selective use may improve its diagnostic and clinical yield and reduce the risk of tube dislodgement. Our study identified trauma and pre-PDT PEEP >5 cm[H.sub.2]O as independent predictors of post-procedure CXR changes. Further studies are required to validate the safety of selective versus routine use of post-procedure CXR following PDT performed without bronchoscopic guidance.
Accepted for publication on December 6, 2006.
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S. H. HADDAD *, A. S. ALDAWOOD ([dagger]), Y. M. ARABI ([double dagger])
Intensive Care Department, King Fahad National Guard Hospital, King Abdulaziz Medical City, Riyadh, Saudi Arabia
* M.D., C.E.S., Consultant, Intensive Care Department, King Fahad National Guard Hospital and Fellow, Surgical Intensive Care Unit, Anesthesia Department, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States.
([dagger]) M.D., F.R.C.P.C., F.C.C.P, Consultant, Intensive Care Department, King Fahad National Guard Hospital and Assistant Professor, King Saud Bin Abdulaziz University for Health Sciences.
([double dagger]) M.D., F.C.C.P, Consultant and Chairman, Intensive Care Department, King Fahad National Guard Hospital and Assistant Professor, King Saud Bin Abdulaziz University for Health Sciences.
Address for reprints: Dr S. H. Haddad, Surgical Intensive Care Unit, Anesthesia Department, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, IA 52242, U.S.A.
TABLE 1 Patients' characteristics Variable Result (%) Number 239 Age [+ or -] SD 54 [+ or -] 22 Male gender 185 (77.4%) Admission category Medical 145 (61%) Surgical 25 (10%) Trauma 67 (28%) Burn 2 (1%) APACHE III [+ or -] SD 79 [+ or -] 29 SD: standard deviation; APACHE: Acute Physiology and Chronic Health Evaluation. TABLE 2 Percutaneous dilatational tracheostomy (PDT) data Variable Result (%) Pre-PDT Fi[O.sub.2] ( [+ or -] SD) 0.33 [+ or -] 0.07 Pre-PDT PEEP [+ or -] SD (cm[H.sub.2]O) 5.8 [+ or -] 3.8 Pre-PDT Fi[O.sub.2] >0.4 20 (8.3%) Pre-PDT PEEP >5 (cm[H.sub.2]O) 58 (24%) PDT without bronchoscopy 228 (95.4%) PDT with bronchoscopy 11 (4.6%) Technique of PDT Griggs (GWFD) 30 (12.5%) Ciaglia (single-step dilation) 209 (87.5%) PDT: percutaneous dilatational tracheostomy; Fi[O.sub.2]: fraction of inspired oxygen; SD: standard deviation; PEEP: positive end- expiratory pressure; GWFD: guide wire forceps dilator. TABLE 3 Univariate predictors of post procedure chest X-ray changes P OR 95% CI Age 0.002 0.97 0.95-0.99 Male gender 0.467 1.52 0.49-4.64 Medical 0.018 0.35 0.15-0.83 Surgical 0.309 0.35 0.04-2.68 Trauma 0.001 4.28 1.80-10.20 APACHE III 0.32 0.99 0.98-1.01 Pre-PDT Fi[O.sub.2] >0.4 0.45 1.66 0.45-6.12 Pre-PDT PEEP >5 (cm[H.sub.2]O) 0.013 3.01 1.27-7.15 Technique of PDT (Ciaglia vs. 0.52 0.69 0.22-2.17 Griggs) Bronchoscopy used 0.368 2.08 0.42-10.24 Perioperative complications 0.445 1.66 0.45-6.15 P: P value; OR: odds ratio; CI: confidence interval; APACHE: Acute Physiology and Chronic Health Evaluation; Fi[O.sub.2]: fraction of inspired oxygen; PEEP: positive end-expiratory pressure; PDT: percutaneous dilatational tracheostomy. TABLE 4 Stepwise regression of predictors of chest X-ray changes Predictor Coefficient SD t-test P value Constant 0.03087 0.02463 1.25 0.211 PEEP >5 0.11515 0.04395 2.62 0.009 Trauma 0.14887 0.04195 3.55 0.000 The regression equation is: any CXR change=0.0309 + 0.115 PEEP >5 + 0.149 trauma.
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|Author:||Haddad, S.H.; Aldawood, A.S.; Arabi, Y.M.|
|Publication:||Anaesthesia and Intensive Care|
|Article Type:||Clinical report|
|Date:||Jun 1, 2007|
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