|Year : 2018 | Volume
| Issue : 2 | Page : 120-126
Validity of ultrasonography in detection of central venous catheter position and pneumothorax compared with portable chest radiography
Mohamed Megahed1, Tamer Habib1, Mohamed Abdelhady1, Haitham Zaki1, Islam Ahmed2
1 Department of Critical Care Medicine, Faculty of Medicine, Alexandria University, Alexandria, Egypt
2 Department of Clinical Pharmacy, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
|Date of Submission||16-Jun-2017|
|Date of Acceptance||06-Dec-2017|
|Date of Web Publication||28-Jun-2018|
Department of Critical Care Medicine, Faculty of Medicine, Alexandria, 21111
Source of Support: None, Conflict of Interest: None
Background Ultrasonographic guidance for insertion of central venous catheters (CVC) is now almost a standard of care, leading to fewer failed attempts and complications. We evaluated the use of ultrasound examination to detect the position of the CVC and pneumothorax (PTX) occurrence after CVC insertion as an alternative to chest radiography (CXR).
Patients and methods This study was carried out on 100 catheter insertions for patients who were admitted to Critical Care Department in Alexandria Main University Hospital. Confirmation of endovenous placement of the catheter was done by ultrasonography using ‘Bubble test’ along with the examination of internal jugular veins and subclavian veins of both sides. Then, lung ultrasound was used to detect PTX occurrence. After that, a portable CXR and computed tomography (CT) of the chest were done for all patients.
Results In detection of the catheter position, the ultrasound showed sensitivity and specificity of 82.7 and 96.8%, respectively, versus 93.8 and 95.8%, respectively, for portable radiography. Furthermore, in detection of postinsertion PTX, the ultrasound showed sensitivity and specificity of 90 and 96.3%, respectively, versus 45 and 96.3%, respectively, for portable CXR.
Conclusion Ultrasound may be used to detect the position of catheter tip and PTX as a better alternative to routine portable CXR with higher accuracy.
Keywords: central venous catheter, chest radiography, critical, pneumothorax, ultrasonography
|How to cite this article:|
Megahed M, Habib T, Abdelhady M, Zaki H, Ahmed I. Validity of ultrasonography in detection of central venous catheter position and pneumothorax compared with portable chest radiography. Res Opin Anesth Intensive Care 2018;5:120-6
|How to cite this URL:|
Megahed M, Habib T, Abdelhady M, Zaki H, Ahmed I. Validity of ultrasonography in detection of central venous catheter position and pneumothorax compared with portable chest radiography. Res Opin Anesth Intensive Care [serial online] 2018 [cited 2018 Jul 20];5:120-6. Available from: http://www.roaic.eg.net/text.asp?2018/5/2/120/235491
| Introduction|| |
Central venous catheterization of the subclavian vein (SCV) and internal jugular vein (IJV) is being performed commonly in intensive care units (ICU). Establishing central venous access is an essential skill for all critical care physicians. Common indications for placement of a central venous catheter (CVC) include the following: (a) hemodynamic monitoring (e.g. measurement of the central venous pressure); (b) administration of medications (e.g. vasopressors, inotropes, chemotherapy, and total parenteral nutrition); (c) plasmapheresis, apheresis, hemodialysis, or continuous renal replacement therapy; and (d) poor peripheral venous access ,.
The modified Seldinger technique is widely used to place CVC. In summary, the vein is cannulated with a needle, and a guidewire is inserted through the needle into the vessel lumen. Once the needle is removed (leaving only the guidewire in position), a tract is dilated, and the catheter is inserted over the guidewire. The guidewire is removed and the CVC is secured ,.
In addition to malpositioning of the CVCs, many other complications are associated with insertion of CVC including arterial puncture, air embolism, catheter occlusion, pneumothorax (PTX), cardiac perforation, and subsequent tamponade, catheter infection, and venous thrombosis ,.
Ultrasound (U/S) imaging is a safe, painless, and noninvasive technique. It produces pictures of the inside of the body using sound waves. U/S examinations do not use ionizing radiation [as used in radiographies and computed tomography (CT)], thus there is no radiation exposure to the patient. Because U/S images are captured in real time, they can show the structure and movement of the body’s internal organs, as well as blood flowing through the blood vessels. Ultrasonographic (USG) guidance for the insertion of CVC is now almost a standard of care, leading to fewer failed attempts and complications ,.
| Aim|| |
The aim of this study was to assess validity of U/S to detect CVC position and postinsertion PTX compared with routine portable chest radiography (CXR).
| Patients and methods|| |
This study was carried on 100 CVC insertions for critically ill patients. Overall, 100 CVC insertions in patients were eligible for this study. These patients were randomly selected from those admitted to the Critical Care Medicine Department of Alexandria Main University Hospital. The study was carried on both sexes. After ethical approval for this clinical trial from the local committee of ethics in the Faculty of Medicine of Alexandria University and the Department of Critical Care, informed consent was taken from patients or their next of kin.
Patients indicated for supradiaphragmatic CVC insertion were included in the study.
The following were the exclusion criteria:
- Patients with anatomical distortions of any cause (e.g. kyphoscoliosis and morbid obesity) that make USG interpretation difficult.
- Patients with chest trauma incidents (e.g. subcutaneous emphysema and dressings) that make USG interpretation difficult.
- Pregnant females.
The USG was performed using a convex probe of portable digital U/S (model DP-20; SHENZHEN Mindray Biomedical Electronics Co. Ltd, Shenzhen, China) of 2.5–5 MHz and a linear probe of 7.5–10 MHz.
- The patient was placed in a supine position, and CVC was inserted using standard Seldinger technique.
- Confirmation of endovenous placement of CVC was done by USG through subcostal view (as a first choice) or apical four-chamber view (as a second choice) with the ‘Bubble test’.
- Positive ‘Bubble test’ was defined as opacification of right atrium after injection of shaken saline, and according to the origin of opacification at the beginning, either central or eccentric opacification (with push-to-bubbles time<3 s), the position of CVC tip was determined if advanced on the right atrium or on superior vena cava (SVC), respectively. In case of eccentric opacification, stopwatch was used to calculate push-to-bubbles time, with taking cutoff value of 3 s . Negative or failed ‘Bubble test’ was defined as no opacification of the right atrium even after 10 s of injection of shaken saline.
- In case of malpositioning (eccentric opacification with push-to-bubbles time>3 s) or a negative ‘Bubble test’ result, examination of both IJVs and both SCVs is done through direct viewing using the linear probe of U/S to detect malposition of the CVC.
- Lung U/S was done to detect the occurrence of PTX using lung-sliding sign or comet-tail artifacts on the upper three intercostal spaces on the same side of CVC insertion.
- A portable chest radiographic film was done for all patients after that to detect the position of catheter tip and the presence of PTX.
- CT of the chest was done after that for all patients after their hemodynamics stabilization to confirm the previous data and compare the accuracy (sensitivity and specificity) of U/S and CXR to detect malposition of CVC tip and PTX resulted from its insertion.
Statistical analysis was done using SPSS statistics program, version 24 (IBM, USA). Categorical variables were summarized by frequency and percentage. χ2-Test was used to study significant association between two qualitative variables. Fischer exact and Monte-Carlo tests were used if more than 20% of total expected cell counts is less than 5 at 0.05 level of significance. κ measure of agreement was done to test agreement between two different diagnosis methods of U/S and CT and also between CXR and CT. Agreement was interpreted as follows: <0.2 poor, 0.21–0.4 fair, 0.41–0.6 moderate, 0.61–0.8 substantial, and 0.81–1 almost perfect agreement.
| Results|| |
The present study was carried on 100 CVC insertions for critically ill patients. These patients were selected randomly from those admitted to the Critical Care Medicine Department of Alexandria Main University Hospital in whom CVC insertion was in supradiaphragmatic site (IJV or SCV on both sides). The basic characteristic features of patients showed that the study represented both sexes, with 60% males and 40% were females. The mean of age in all enrolled patients was 51.2 years. The most common diagnosis in all enrolled patients was septic shock (62%).
The site of insertion of CVC for patients was chosen according to personal preference. The first preferred site for CVC insertion was right IJV (48%), and the second one was right SCV (20%). After insertion of CVC, bubbling test was used by agitated saline and U/S (curved probe) on subcostal window (as a first option) or apical window (as a second option) to view right atrium to identify position of tip of catheter. The bubbling test result was positive in 85% of all patients ([Table 1]).
|Table 1 Distribution of patients according to site of insertion of central venous catheter|
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According to the pattern of opacification of bubbles ([Figure 1]), we determined if the tip of CVC was advanced in right atrium (central opacification), in SVC (eccentric opacification, with short push-to-bubbles time<3 s), or malpositioned (eccentric opacification, with delayed push-to-bubbles time>3 s). In contrast, the bubbling test result was negative in 15% of patients. In case of positive bubbling test result with malpositioned CVC or negative bubbling test result, a linear probe of U/S was used to detect the tip position by viewing it directly in one of the big veins (SCV, IJV) on both sides. After that, portable radiography and CT chest were done for all patients to detect tip position of CVC. Results were collected and analyzed ([Figure 1] and [Table 2]).
|Figure 1 Opacification pattern of bubbling test: (a) central one and (b) eccentric one. LA, left atrium; LV, left ventricle; RA, right atrium.|
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|Table 2 Detection of central venous catheter position by ultrasound versus computed tomography|
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Results showed that there was a significant agreement between determination of CVC tip position by U/S (using bubbling test) and CT chest (P<0.001); κ value of 0.878 with 95% confidence interval from 0.790 to 0.965 indicates that strength of agreement is ‘perfect’. Validity of U/S to detect the position of CVC is as follows: specificity of 96.76%, sensitivity of 82.74%, PPV of 84.89%, and NPP of 97.19% ([Figure 2] and [Figure 3] and [Table 3]).
|Figure 2 Detection of central venous catheter position by ultrasound versus computed tomography (CT) chest. Lt. IJV, left internal jugular vein; Lt. SCV, left subclavian vein; Rt. SCV, right subclavian vein; SVC, superior vena cava.|
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|Figure 3 Receiver operating characteristic (ROC) curve for detection of position of central venous catheter using radiography and ultrasound (U/S).|
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|Table 3 Detection of central venous catheter position by portable chest radiography versus computed tomography chest|
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Results showed that there was a significant agreement between determination of CVC tip position by portable CXR and CT chest (P<0.001); κ value of 0.829 with 95% confidence interval from 0.725 to 0.932 indicates that strength of agreement is ‘perfect’. Validity of portable radiography to detect position of CVC is as follows: specificity of 95.82%, sensitivity of 93.77%, PPV of 95.54%, and NPP of 96.76% ([Figure 3] and [Figure 4]).
|Figure 4 Detection of central venous catheter position by portable radiography versus computed tomography (CT) chest. CXR, chest X-ray; Lt. IJV, left internal jugular vein; Lt. SCV, left subclavian vein; Rt. SCV, right subclavian vein; SVC, superior vena cava.|
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Regarding the distribution of cases of PTX according to site of insertion, the incidence of PTX occurrence was more with subclavian approach (80%) than using internal jugular approach (20%). Results showed that there was a significant agreement between identification of PTX by U/S and CT chest (as a gold standard test) (P<0.001), and κ value of 0.724 with 95% confidence interval from 0.716 to 0.977 indicates that strength of agreement is ‘substantial’. The validity of U/S to detect PTX is as follow: specificity is 96.3%, sensitivity is 90%, negative predictive value (NPV) is 97.5%, and positive predictive value (PPV) is 85.7 ([Table 4] and [Figure 5]).
|Table 4 Detection of pneumothorax by ultrasonography versus computed tomography|
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|Figure 5 Receiver operating characteristic (ROC) curve for detection of pneumothorax using radiography and ultrasound (U/S).|
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Results showed that there was a significant agreement between determination of CVC tip position by U/S (using bubbling test) and CT chest (as a gold standard test) (Ρ<0.001), and κ value of 0.597 with 95% confidence interval from 0.259 to 0.712 indicates that strength of agreement is ‘moderate’. The validity of portable radiography to detect PTX is as follows: specificity of 96.3%, sensitivity of 45%, NPV of 87.5%, and PPV of 75% ([Table 5]).
|Table 5 Detection of pneumothorax by portable radiography versus computed tomography|
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| Discussion|| |
USG guidance for the insertion of CVC is now almost a standard of care, leading to fewer failed attempts and complications. However, the risk of inadvertent puncture of surrounding structure persists. Carotid artery puncture and/or cannulation may occur even if proper precautions are taken, sometimes with disastrous consequences . Furthermore, U/S is used after CVC insertion to detect position of its tip and exclude occurrence of iatrogenic PTX.
In this study, the subclavian approach has higher risk for occurrence of post-CVC insertion PTX. In agreement with this finding, Eisen et al., mentioned that the subclavian approach had a higher complication rate than the internal jugular or femoral approach . In contrast, Schummer et al., mentioned that the incidence of PTX was not related to the insertion site . In this study, determination of CVC position by U/S using bubbling test was the first step after CVC insertion. The USG examination was performed by critical care resident who had undergone 2 days of training on cardiac-focusing USG with an expert cardiologist. The researcher used an U/S curved probe on subcostal or apical window for right atrium by using an agitated saline injected on largest port on CVC with notification of opacification pattern either central (turbulent flow) or eccentric (laminar jet flow) one.
In contrast to this study, a systematic review done by Ruesch et al. , who studied complications of CVC with 10 trials (with total 3420 CVC insertions), mentioned that the incidence of hemothorax or PTX was 1.3 versus 1.5%, with no evidence of any difference between both approaches. Moreover, Alonso-Quintela et al. , who studied mechanical complications and malpositioning of CVC by experienced operators on a prospective study of 1794 catheterization in critically ill patients, found that the incidence of PTX was not related to the insertion site.
U/S showed sensitivity, specificity, PPV, and NPV of 89.65, 96.5, 96.9, and 97.2%, respectively, taking CT scan as a gold standard test. After that a portable CXR film was done for all patients and the results were reported by an expert radiologist who was blinded to the USG results. Moreover, the portable CXR showed sensitivity, specificity, PPV, and NPV of 85.8, 90.3, 87.2, and 91.1%, respectively. Throughout this study, low sensitivity of USG in detection of CVC position is explained by some cases (six CVCs) in which the CVC tip was just beyond the junction between SVC and right atrium (seen by CT scan) which showed eccentric flow and was interpreted as positioned in SVC by U/S. In agreement with this findings, Alonso Quitela et al. mentioned that the bedside U/S showed good agreement with CXR in detecting CVC tip and revealing incorrect position; the study was conducted in pediatric patients aged from 0 to 14 years old . Gehring et al. found that U/S can confirm CVC placement and rule out PTX significantly faster than CXR with sensitivity and specificity 96 and 93%, respectively . In contrast, Kamalipour et al.  mentioned that despite the close concordance between U/S and CXR, contrast-enhanced U/S (Bubble test) was not suitable alternative to standard CXR in detecting CVC location; yet, considering its high sensitivity and acceptable specificity in his study, its usefulness as a triage method for detecting CVC location on a real-time basis in the operating room cannot be ignored.
Lung U/S was used to detect presence of iatrogenic PTX or not after CVC insertion by using lung-sliding and comet-tail artifact signs. There was a statistically significant difference between U/S and CXR in detecting PTX, which promote the usage of bedside U/S as a better alternative than portable CXR with higher sensitivity. In agreement with this findings, Mumtaz et al.  mentioned that U/S can be used as a useful and suitable adjunct to CT in trauma patients, as it is easily available, is noninvasive, can be used at the bedside, and can be used easily for examining, with no radiation risk; the specificity and sensitivity of U/S to detect PTX was 94 and 100%, and for radiography was 31.8 and 100%, respectively.
Similarly, Blaivas et al.  conducted a prospective comparison of supine CXR and bedside U/S for diagnosis of traumatic PTX in 176 patients, and they found that with CT as the criterion standard, U/S is more sensitive (98.1 vs. 75.5%) than flat AP CXR in the diagnosis of traumatic PTX. Moreover, Zhang et al. , who studied rapid detection of PTX by U/S on patient with multiple trauma over 14 months on 135 patients, mentioned that bedside clinician-performed U/S provides a reliable tool and has the advantages of being simple and rapid and having higher sensitivity (86.2 vs. 27.6%) and accuracy (94.8 vs. 84.4%) compared with CXR for detection of PTX in patients with multiple trauma. Similarly, Ball et al. noted that up to 76% of all traumatic PTX were missed by standard supine anteroposterior chest film when interpreted by trauma team.
Moreover, Gentry Wilkerson and Stone  studied the sensitivity of bedside U/S and supine anteroposterior CXR for identification of PTX after blunt trauma in adult patients aged 18 years or older and found that bedside thoracic U/S is more a sensitive screening test than supine anteroposterior CXR (range: 86–98% vs. 28–75%) for the detection of PTX in adult patients with blunt chest trauma.
| Conclusion|| |
Bedside U/S in the ICU is increasingly being used. This study suggests that ultrasonic examination is accurate in detecting PTX and catheter position after SCV and IJV cannulation. Furthermore, the U/S can be used as a good alternative to routine portable CXR post-CVC insertion with better accuracy. The present study has a limitation; in case of a positive bubbling test result with eccentric opacification, the cutoff point value to differentiate between two positions (SVC vs. malpositioned catheter) was determined according to previous studies, and it was not tested.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]