Assessment of the value of the immediate postoperative chest radiograph after cardiac operation

Assessment of the Value of the Immediate Postoperative Chest Radiograph After Cardiac Operation Philip I. Hornick, FRCS, Paul Harris, MB, BS, Claire Cousins, FRCR, Kenneth M. Taylor, FRCS, and Bruce E. Keogh, FRCS Departments of Cardiothoracic Surgery and Radiology, Hammersmith Hospital, London, England

The value of the immediate postoperative chest radiograph upon a patient's return to the intensive care unit after a cardiac surgical procedure is uncertain. This study represents a prospective analysis of the immediate postoperative radiograph in 100 consecutive adult patients undergoing cardiac operations. In 11 patients it was found that the routine postoperative radiograph was of value w h e n it was necessary either to clarify or confirm clinical findings or to check the position of an intraaortic balloon catheter. For those chest radiographs that were d e e m e d unnecessary, only one of 89 were found to be of

clinical value. Furthermore, in those situations in which an emergency radiograph was obtained, the routine radiograph was not found to be contributory to patient management. We conclude that the policy of obtaining routine, immediate postoperative chest radiographs in the absence of a specific clinical indication provides virtually no additional clinical yield. Residents should therefore request radiographs only to check the position of an intraaortic balloon catheter, and to clarify or confirm a clinical diagnosis.

fter cardiac surgical p r o c e d u r e s it is a c o m m o n practice to routinely perform chest r a d i o g r a p h y u p o n return of the patient to the intensive care unit [1-3], but the contribution of this investigation to patient m a n a g e m e n t n e e d s to be assessed. Furthermore, at those times w h e n a patient's h e m o d y n a m i c or respiratory function, or both, s u b s e q u e n t l y deteriorate, another chest r a d i o g r a p h is usually obtained. Each chest r a d i o g r a p h increases the financial b u r d e n p l a c e d on the cardiothoracic unit. The p u r p o s e of this study was to assess the contribution of the first r a d i o g r a p h to patient m a n a g e ment.

graph. I m m e d i a t e l y u p o n the patient's return to the intensive care unit, a chest r a d i o g r a p h was o b t a i n e d in all 100 patients. After this the resident (either P.H. or P.I.H.) m a d e a full clinical a s s e s s m e n t of the patient, which i n c l u d e d a physical examination a n d a s s e s s m e n t of hem o d y n a m i c , respiratory a n d renal function p e r f o r m e d according to a strict protocol. The resident was then asked to record his findings a n d w h e t h e r the p a t i e n t ' s m a n a g e m e n t should be altered, and, if so, the nature of the therapeutic change to be instituted. The r e s i d e n t was then a s k e d w h e t h e r he or she w o u l d like to see the chest r a d i o g r a p h that h a d b e e n obtained. If the a n s w e r was affirmative, the reason for this was r e c o r d e d (Results 1). Regardless of the decision made, the resident then recorded the chest r a d i o g r a p h findings for each patient. Information o b t a i n e d from the chest r a d i o g r a p h was c o m p a r e d with that y i e l d e d by the r e s i d e n t ' s clinical assessment, a n d the contribution m a d e b y the radiog r a p h to the p a t i e n t ' s m a n a g e m e n t was r e c o r d e d (Results 2). Finally, if there was a n e e d for an additional chest r a d i o g r a p h before chest drain removal, this was noted, together with the indication. The resident then assessed any contribution m a d e by the first chest r a d i o g r a p h to the interpretation of the n e w r a d i o g r a p h (Results 3). A limitation of the study design was that, of necessity, the resident was not b l i n d e d as to the identity of the patients from w h o m the r a d i o g r a p h s came. However, in an att e m p t to minimize any i n h e r e n t bias, the chest radiographs of all patients were s u b s e q u e n t l y r e v i e w e d b y a consultant radiologist (C.C.) a n d consultant cardiothoracic surgeon, i n d e p e n d e n t of (and therefore b l i n d to) the resident's findings. Finally, the consultant surgeon re-

A

Patients and Methods Between March 1993 a n d June 1993, 100 consecutive adult cardiac surgical patients were assessed clinically a n d b y chest r a d i o g r a p h y i m m e d i a t e l y u p o n their return to the intensive care unit. There were 62 male a n d 38 female patients. The m e a n age of all patients was 63 years (range, 25 to 85 years). O p e r a t i o n s were p e r f o r m e d b y either K.M.T., B.E.K., or P.I.H., a n d the patients u n d e r w e n t a variety of different adult cardiac surgical procedures (Table 1). The average n u m b e r of coronary artery b y p a s s grafts p e r patient was 4.1, with a 92% use of the left internal m a m m a r y artery a n d a 3% use of the right gastroepiploic artery. Figure 1 shows the m e t h o d o l o g y u s e d to ascertain the clinical value of the i m m e d i a t e postoperative chest radioAccepted for publication Jan 18, 1995. Address reprint requests to Mr Hornick, Department of Cardiothoracic Surgery, Hammersmith Hospital, Du Cane Rd, London, England, W12 OHS.

© 1995 by The Society of Thoracic Surgeons

(Ann Thorac Surg 1995;59:1150-4)

0003-4975/95/$9.50 0003-4975(95)00087-2

Ann Thorac Surg

H O R N I C K ET AL CHEST R A D I O G R A P H IN CARDIAC OPERATIONS

1995;59:1150-4

Table 1. Operative Procedures Performed in 100 Consecutive Elective

Redo

Emergency

62

5

4

8

2

1

6

0

0

2

0

0

3

0

0

2

0

0

In this series atelectasis was defined as areas of subsegmental collapse, which is typically platelike or linear. Collapse was defined as obstruction of segmental or lobar airways with diminution of lung volume. Consolidation was characterized by an irregularly shaped increased density, ill-defined margins, a nonsegmental distribution, and the presence of an air bronchogram. Pulmonary e d e m a e n c o m p a s s e d both the radiologic forms of interstitial and alveolar edema. Any disparities in the interpretation of the radiologic studies and the m a n a g e m e n t decided upon b e t w e e n the resident and the independent reviewer were recorded (Results 4).

0

0

3

Results

1

1

0

Patients Operative Procedure Coronary artery bypass grafts Aortic valve replacements Mitral valve replacements Mitral valve repair Coronary artery bypass grafts and aortic v a l v e replacement Coronary artery bypass grafts and mitral valve replacement Aortic dissection Atrial septal defect

viewed the clinical data (in the light of his and the radiologist's interpretation of the radiograph) to assess whether the clinical decisions m a d e by the resident were appropriate.

Results 1: Residents" Use of the Routine Immediate Postoperative Chest Radiograph In 89 of the patients the resident d e e m e d it unnecessary to v i e w the immediate postoperative chest radiograph and considered the clinical assessment of the patient sufficient. In the remaining 11 patients w h o s e studies the resident w i s h e d to see, this was done to confirm a clinical

Fig 1. Methodology used in the assessment of the immediate postoperative chest radiograph (CXR). ( I A B P = intraaortic balloon pump.)

RETURN FROM THEAT--=.R

I

I I

CL fiNICA L ASSESSMENT

MANAGEMENT DECISION 1 RECORDED

WOULD RESIDENT LIKE TO SEE CXR?

I

I NO

I ~

CONFIRM CLINICAL FINDINGS

YES

I REASON?

CLARIFY CLINICAL FINDINGS CHECK POSITION OF IABP

ALL CXR'S EXAMINED BY RESIDENT AND FINDINGS RECORDED

RETROSPECTIVE ANALYSIS OF C X R AND DATA BY CONSULTANT RADIOLOGIST AND SURGEON

ANALYSIS OF CXR 'IX)GETI-IER WITH CLINICAL EXAMINATION

MANAGEMENT DECISION 2 RECORDED NO--

1151

NEED FOR ADDITIONAL/EMERGENCY CXR PRIOR TO DRAIN REMOVAL

I I

YES

WAS THE IMMEDIATE POSTOP FILM HELPFUL FOR COMPARISON?

MANAGEMENT DECISION 3 RECORDED

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HORNICKET AL CHEST RADIOGRAPHIN CARDIACOPERATIONS

Table 2. Analysis of Routine Postoperative Chest Radiograph by Resident Routine Immediate CXR Deemed unnecessary Confirm clinical findings Clarify clinical findings Check position of intraaortic balloon catheter

Number of Cases 89 2 5 4

Routine CXR Contributory to Clinical Assessment

Routine CXR Noncontributory to Clinical Assessment

1 (malpositioned central line) 2 (pneumothorax)

88

5 (pulmonary edema) 4

0 0 0

CXR = chest radiograph.

diagnosis in 2, to clarify the diagnosis in 5, a n d to check the position of an intraaortic balloon catheter in 4.

Results 2: Analysis of the Contribution to Patient Management Made by the Routine Postoperative Chest Radiograph Of the 89 patients whose routine chest r a d i o g r a p h was d e e m e d u n n e c e s s a r y by the resident, the information p r o v i d e d by this r a d i o g r a p h was found to be contributory to patient m a n a g e m e n t for only 1 patient by revealing a m a l p o s i t i o n e d central line. In the r e m a i n i n g 11 patients, the routine chest r a d i o g r a p h was of use in clarifying or confirming clinical findings or in checking the position of an intraaortic balloon catheter. In these cases the routine chest r a d i o g r a p h h a d b e e n d e e m e d necessary b y the resident. The results of the r e s i d e n t s ' analysis are summ a r i z e d in Table 2.

Results 3: Assessment of the Value of the Routine Chest Radiograph When a Further Chest Radiograph Was Obtained Before Removal of Drains In 15 patients it was necessary to obtain an additional r a d i o g r a p h before the removal of chest drains because of poor arterial b l o o d gas levels or h e m o d y n a m i c instability. In no patient was the routine postoperative chest radiograph found to be of value in the a s s e s s m e n t of the n e w e r radiograph, a n d the routine study was therefore d e e m e d noncontributory to patient m a n a g e m e n t .

Results 4: Independent Review of the Immediate Postoperative Radiograph and Clinical Management by a Consultant Radiologist and Consultant Cardiothoracic Surgeon All i m m e d i a t e postoperative chest r a d i o g r a p h s were rev i e w e d retrospectively by a consultant radiologist a n d cardiothoracic surgeon. There was a 100% concordance in the specific radiologic abnormalities identified b y both of them. There was an 89% concordance with the radiographic interpretation of the surgical resident. The results of the radiologist's a n d cardiac surgeon's interpretation for each a b n o r m a l i t y taken in isolation are shown

Ann Thorac Surg 1995;59:1150-4

in Table 3. The most c o m m o n a b n o r m a l i t y o b s e r v e d was consolidation. No abnormalities were detected in 4 patients. In those 11 patients for w h o m there was discordance b e t w e e n the r e s i d e n t ' s interpretation of the routine r a d i o g r a p h s a n d that of the i n d e p e n d e n t reviewers (atelectasis, 5 patients; pleural effusion, 4 patients; lobar collapse, 2 patients), the clinical m a n a g e m e n t of these patients r e c o m m e n d e d by the resident was, nonetheless, j u d g e d correct by the consultant cardiac surgeon.

Comment The i m m e d i a t e postoperative chest r a d i o g r a p h o b t a i n e d after a cardiac operation is a c o m m o n practice b u t of uncertain value. Some units do not follow this practice [4, 5]. Furthermore, deterioration in a p a t i e n t ' s condition frequently necessitates a n o t h e r chest r a d i o g r a p h (15% in this series). Investigations p e r f o r m e d routinely often have a limited impact on patient m a n a g e m e n t . In this study the n e e d for the i m m e d i a t e postoperative chest r a d i o g r a p h was evaluated by c o m p a r i n g the results of the clinical a s s e s s m e n t a n d the patient m a n a g e m e n t instituted both with a n d without the information furnished b y this radiograph. In an a t t e m p t to eliminate any i n h e r e n t bias a n d provide quality control in the r e s i d e n t ' s radiographic interpretation a n d decision r e g a r d i n g patient m a n a g e ment, all data were s u b s e q u e n t l y analyzed by a consultant radiologist a n d a consultant cardiothoracic surgeon. In addition, the value of the i m m e d i a t e r a d i o g r a p h has b e e n assessed from the s t a n d p o i n t of its p r o v i d i n g baseline information for the evaluation of further chest radiographs o b t a i n e d to identify the sources of h e m o d y n a m i c instability or poor respiratory function. The surgical resident d e e m e d the routine p o s t o p e r a tive chest r a d i o g r a p h to be of value in 11% of the patients. It was considered m a n d a t o r y in patients who h a d an intraaortic balloon catheter to verify its position. This r a d i o g r a p h was also of clinical value w h e n confirming

Table 3. Radiographic Abnormalities Found on the Routine Postoperative Chest Radiographs by Consultant Radiologist and Consultant Cardiac Surgeona Radiographic Abnormality Atelectasis Pneumothorax Consolidation Eff-usion Collapse Intraaortic balloon Central venous pressure line malposition Endotracheal tube malposition

Right

Left

Bilateral

Total

7.9 2.0 10.5 5.3 0 0 1

18.4 0 47.4 28.9 18.4 4 0

2.6 0 7.9 7.9 0 0 0

28.9 2.0 65.8 42.1 18.4 4.0 1.0

0

0

0

0

For every routine postoperative chest radiograph, the frequency of each radiographic abnormality taken in isolation is expressed as a percentage.

Ann Thorac Surg 1995;59:1150-4

the presence of a suspected pneumothorax. In this series the two pneumothoraces were suspected by the resident after clinical assessment, and confirmed by analysis of the chest radiograph. They would have been manifested before, or soon after, the patient's return to the intensive care unit. This radiograph would, however, have been of no value should they have occurred later. In addition, the routine radiograph was of value to the surgical resident in the 5 patients who required clarification of the clinical findings. In these 5 patients the radiographic diagnosis confirmed the presence of pulmonary edema. The radiologic abnormalities observed after cardiopulmonary bypass encountered in our study differ from those reported by other authors [1-3, 5]° Postoperative atelectasis was not as c o m m o n a finding as consolidation in these other studies. The important finding of our study was that, of the 89 chest radiographs that were d e e m e d unnecessary by the surgical resident, only one was found to alter patient m a n a g e m e n t by detecting a malpositioned central line not suspected on the basis of the clinical assessment. Furthermore, in no patient in w h o m a second, later, chest radiograph was requested before drain removal was the initial chest radiograph helpful. The immediate routine

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postoperative chest radiograph is of value whenever the resident wishes to confirm or clarify the clinical findings noted at that time, or to check the position of an intraaortic balloon catheter. Our study findings demonstrate that, in the absence of a specific clinical indication, the immediate routine postoperative chest radiograph provides virtually no additional useful information and its omission would be a cost saving for any cardiothoracic unit.

References 1. Gale GD, Teasdale SJ, Sanders DE, et al. Pulmonary atelectasis and other respiratory complications after cardiopulmonary bypass and investigation of aetiological factors. Can Anaesth Soc 1979;26:15-21. 2. Goodman LR. Postoperative chest radiograph: II. Alterations after major intrathoracic surgery. Am J Roentgenol 1980;134: 803-13. 3. Wiener-Kronish JP. Postoperative pleural and pulmonary abnormalities in patients undergoing coronary bypass grafts [Editoriall. Chest 1992;102:1313-14. 4. Chong JL, Pillai R, Fisher A, Grebenik C, Sinclair M, Westaby S. Cardiac surgery: moving away from the intensive care. Br Heart J 1992;68:430-3. 5. Aps C, Hutter JA, Williams BT. Anaesthetic management and postoperative care of cardiac surgical patients in a general recovery ward. Anaesthesia 1986;41:533-7.

INVITED COMMENTARY Hornick and associates have questioned the usefulness of the immediate postoperative chest radiograph after adult cardiac operations, a routine that has been followed faithfully in most postsurgical care units since their inception. The proposal to abolish this early postoperative radiograph, in the absence of specific clinical indications, is very attractive in today's economic climate. In another setting, Silverstein and associates [1] reported an extremely low yield of clinically significant and unsuspected new cardiopulmonary findings or device malpositions in a prospective evaluation of 525 routine morning chest radiographs in two surgical intensive care units and concluded that the need for a routine daily chest radiograph should be based on clinical necessity. It does seem rational to expect that shorter-acting anesthetic agents, better intraoperative myocardial preservation, improved surgical technique, and shorter bypass times should lead to fewer postoperative complications and the need for fewer assessments. This assumes that these advances in care are not offset by increased age and poorer ventricular function of the patient population and the increase in n u m b e r and complexity of grafts done. There are a few specific situations relevant to cardiac surgery and the postoperative radiograph that should be considered. Bilateral internal m a m m a r y artery grafts have been shown to be associated with a higher incidence of respiratory complications including clinically significant diaphragmatic dysfunction [2]. Gastroepiploic artery grafting can be associated with air under the diaphragm, which could confuse subsequent diagnosis in

the (albeit rare) instance of an abdominal crisis. Physical examination cannot identify invariably an expanding pneumothorax (the post-chest tube removal radiograph, another routine, is done for this very purpose). Some surgical staff may not make a point of communicating all their intraoperative difficulties and anticipated postoperative complications (eg, possible pneumothorax) to the staff in the postoperative unit. Chest radiographs may be needed to check positions of central venous catheters unless pressure-guided pulmonary artery catheters always are used. The mediasfinum in the p o s t - o p e n heart radiograph is 35°/, wider on average than in the preoperative radiograph [3] and thus provides a better comparison with subsequent chest radiographs to help confirm postoperative bleeding (recognizing that the echocardiogram has replaced the chest radiograph in the diagnosis of pericardial tamponade). Although the residents involved in this study did not interpret correctly (according to the radiologist and staff surgeon) 11% of the radiographs, including two of patients with lobar collapse and four of patients with pleural effusion, the clinical m a n a g e m e n t followed by the resident was deemed to be correct by the consultant cardiac surgeon in all cases. It has long been recognized that post-cardiac surgical patients have a high incidence of atelectasis, effusion, and consolidation (and, to a lesser extent, pulmonary congestion), as demonstrated by an early marked fall in arterial oxygen tension [4]. Consequently, most centers have an established postoperative respiratory m a n a g e m e n t regimen to address these antic-

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ipated changes, as was u n d o u b t e d l y the case in Hornick a n d associates' unit. It is fallacious to argue that a chest radiograph should be done to confirm the presence or extent of an abnormality if n o t h i n g more can be done to improve it b e y o n d the usual regimen, but is this always the case? Light's group [5] found that the combination of atelectasis a n d pleural changes on the chest radiograph correlated with more significant gas exchange abnormalities than either finding alone. Valta's group [6] showed that the application of 10 cm H20 or more of positive end-expiratory pressure caused significant a n d lasting recruitment of atelectatic lung units. The application of increased positive end-expiratory pressure might be particularly important to improve postextubation arterial oxygen tension, in units where early extubation is practiced. We are i n d e b t e d to Hornick a n d associates for r e m i n d ing us that all routine screening procedures should be assessed regularly for usefulness. I agree that the i m m e diate postoperative chest radiograph may not always be useful a n d may even be a threat to the patient's hemodynamic stability if elevating the patient's thorax to position the film is required. Although much can be d e t e r m i n e d on the basis of clinical examination of the patient and the blood gas results, each cardiac surgical unit should first examine its own practices a n d review its own protocols before eliminating the routine immediate

Ann Thorac Surg 1995;59:1150-4

postoperative chest radiograph on the basis of this relatively small study.

SaUie J. Teasdale Scott, FRCP(C) Greater Victoria Hospital Society Victoria, British Columbia Canada References 1. Silverstein DS, Livingston DH, Elcavage J, Kovar L, Kelly KM. The utility of routine daily chest radiography in the surgical intensive care unit. J Trauma 1993;35:643-6. 2. Galbut DL, Traad EA, Dorman MJ, et al. Twelve year experience with bilateral internal mammary artery grafts. Ann Thorac Surg 1985;40:264-70. 3. Goodman LR. Postoperative chest radiograph: II. Alterations after major intrathoracic surgery. Am J Roentgenol 1980;134: 803-13. 4. Taggert DT, EI-Fiky M, Carter R, Bowman A, Wheatley DJ. Respiratory dysfunction after uncomplicated cardiopulmonary bypass. Ann Thorac Surg 1993;56:1123-8. 5. Vargas FS, Cukier A, Terra-Filho M, Hueb W, Teixeira LR, Light RW. Postoperative pleural and pulmonary abnormalities in patients undergoing coronary artery bypass grafts. Chest 1992;102:1333-6. 6. Valta P, Takala J, Elissa NT, Milic-Emili J. Effects of PEEP on respiratory mechanics after open heart surgery. Chest 1992; 102:227-33.

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