Relationship between intraoperative transoesophageal echocardiography findings and perfusion lung scintigraphy results on first postoperative day

M. Moriyama1, S. Watanabe1,*, T. Hiraki1, T. Kano1, T. Okawa2 and M. Ishibashi3

1 Department of Anaesthesiology, 2 Department of Orthopaedic Surgery and 3 Department of Radiology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka 830-0011, Japan

* Corresponding author. E-mail: watanabe{at}med.kurume-u.ac.jp

Accepted for publication October 22, 2004.


    Abstract
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Background. Although intraoperative transoesophageal echocardiography (TOE) has been used to detect the occurrence of echogenic macro- and/or microembolic phenomena during total hip arthroplasty (THA), no direct correlation between macroembolism and the formation of pulmonary embolism (PE) has been conclusively determined in early postoperative periods after THA.

Methods. Sixty-two patients scheduled for primary THA were enrolled in this study. Intraoperative TOE images were continuously recorded on videotape and the echogenic events were evaluated throughout surgery. Perfusion lung scintigraphy was performed on the first postoperative day (POD1).

Results. Perfusion lung scintigraphy revealed the existence of PE in nine (15%) of the 62 patients who underwent THA: five (25%) of 20 patients with cemented THA and four (10%) of 42 patients with non-cemented THA. The grading score of intraoperative TOE findings, including the amount of echogenic particles in right atrium, the longest time of echogenesis and the diameter of the largest echogenic particles, did not differ between the groups with and without PE. The sensitivity, specificity, and positive and negative predictive values for the detection of echogenic macroemboli for the prediction of the development of PE on POD1 were 0.78, 0.60, 0.25 and 0.94, respectively.

Conclusion. Intraoperative TOE monitoring did not predict the occurrence of PE on POD1.

Keywords: embolism, pulmonary ; measurement techniques, perfusion lung scintigraphy ; monitoring, transoesophageal echocardiography ; surgery, total hip arthroplasty


    Introduction
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
The perioperative mortality of patients undergoing total hip arthroplasty (THA) has been reported to be 0.1–0.2%.1 Pulmonary embolism (PE) is a known complication of THA, and can lead to sudden death or severe cardiopulmonary impairment.15 Despite recent advances in prophylaxis,6 7 diagnostic modalities8 9 and therapeutic options for PE,10 it is still a significant clinical issue. Thus the availability of clinical indicators for patients at high risk might result in improving patient outcomes through early detection and treatment.

Previously, deep vein thrombosis (DVT) was thought to be the major cause of delayed PE following THA.11 However, recent studies using transoesophageal echocardiography (TOE) have clearly detected variable echogenic events, such as snowstorm patterns and/or macroemboli in the bloodstream flowing into the right atrium (RA) in 90–98% of THA patients.1214 The echogenic events were assumed to consist of bone marrow, fat and bone debris which diffused into the venous system from the femur medullar cavity because of the increased pressure at insertion of an artificial femoral prosthesis.15 Use of bone cement to fix the artificial prosthesis is reported to augment the frequency and severity of echogenic events during THA procedures.12 Echogenic macroemboli detected by TOE might cause the development of PE during and after THA. Although TOE has been used to detect the occurrence of echogenic macro- and/or microembolic phenomena during THA, the direct correlation of macroembolism with the formation of PE has not been conclusively determined in early postoperative periods after THA. Pulmonary angiography, a ‘gold standard’ confirmatory test for detection of PE, is invasive and may cause further complications such as bleeding or thrombus.16 Perfusion lung scintigraphy (PLS), which is less invasive, has been used conventionally as a means to evaluate PE.8 9 PLS is also superior for detecting macroembolism instead of microembolism in the lung field. Therefore we carried out PLS on the first postoperative day (POD1) and evaluated the cause–effect relationship between the intraoperative appearance of echogenic macroemboli and subsequent PE development.


    Patients and methods
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
The protocol for this study was approved by the university ethics committee and written informed consent was obtained from all subjects prior to the study. The study was carried out between December 2000 and January 2003. Patients with severe chronic obstructive pulmonary disease or clinical symptoms of DVT were excluded before the operation. Patients who received anticoagulation therapy within 1 week were also excluded. All the operations were elective, and patients with fractured femur were not included.

Sixty-two patients scheduled for primary THA were enrolled in this study. The subjects were not randomized and were divided into two groups depending on whether bone cement was used to fix an artificial prosthesis without any venting techniques during the THA. The criteria for allocation to the cemented or non-cemented THA group were set by the same orthopaedic surgeon based on underlying pathological condition, age and gender, but not on the cardiopulmonary condition. The subjects were retrospectively classified into two groups according to the occurrence of PE evaluated by PLS on POD1.

Patients were premedicated 1 h before arrival in the operating room with oral flunitrazepam 1 mg or i.m. midazolam 2 mg. An epidural catheter was placed at a high lumbar level (L1/2 or L2/3) before induction of anaesthesia. Mepivacaine 2% (6–8 ml) was injected through the catheter every 60–90 min during surgery, followed by continuous postoperative infusion of mepivacaine 1% at a rate of 4 ml h–1 for pain relief. Anaesthesia was induced with i.v. thiopental 5 mg kg–1 combined with fentanyl 100 µg with supplementary inhalation of sevoflurane (1–2% end-tidal). The trachea was intubated after i.v. vecuronium 0.1 mg kg–1 and the lungs were ventilated to maintain end-tidal carbon dioxide () at a normal level. Subsequent anaesthesia was maintained with the inhalation of nitrous oxide ( 0.5) and sevoflurane (1–2% end-tidal) as needed. The ECG, non-invasive measurement of arterial blood pressure, pulse oximetry, and were monitored during surgery. The ECG, non-invasive measurement of arterial blood pressure and pulse oximetry were also monitored after the operation. First, TOE examination with Colored Flow Doppler (SONOS5500, Philips, USA) was used to determine whether an intracardiac shunt existed under mechanical positive-pressure ventilation. The TOE multiplane probe (4–7 MHz Omniplane II, Philips, USA) was then positioned to obtain a longitudinal view of both the right and left atria, where it was possible to detect the inflow of embolic materials from the inferior vena cava to the RA. Patients were placed in the lateral decubitus position with the surgical side up. TOE images obtained in this situation were continuously observed and recorded on videotape throughout surgery.

The analogue images of serious echogenic events were digitized and transferred to AVI files (30 fps) without compression (Power Capture Pro, Canopus, Japan) for later computer analysis. An anaesthetist blinded to the classification of patients performed the offline analysis of TOE images. The echogenic events detected by intraoperative TOE were evaluated based on Ereth's classification,12 which included the amount of echogenic particles in RA, the longest time of echogenesis and the diameter of the largest echogenic particles during surgery. To calculate sensitivity, specificity, and positive and negative predictive values of echogenic macroemboli for the development of subsequent PE on POD1, the presence of echogenic macroemboli was taken as positive when the diameter of the largest echogenic particles was >5 mm.12

Although an elastic stocking was used after surgery, subcutaneous injection of unfractionated heparin was not routinely given for the prevention of PE on POD0 because of postoperative bleeding from the bone marrow. The PLS examination was performed and the epidural tubing was removed before the subcutaneous injection of heparin on POD1. PLS was performed using macro-aggregated [99mTc]albumin on POD1 and was evaluated by a radiologist blinded to group identity. PE was diagnosed as positive when the PLS result was categorized as high, intermediate or low probability, but not at very low probability according to the criteria of a previous study using the ventilation–perfusion scan.8 When PE was diagnosed as positive, the PLS examination was repeated and disappearance or involution of PE was confirmed 2–3 weeks later. A chest radiograph was also used instead of a ventilation scan to aid the evaluation of perfusion defects on lung scintigraphy.

Statistical analyses were performed using a commercially available statistics package (SPSS Ver11.5J). All data are expressed as mean (SD). The statistical significance of the haemodynamic and respiratory data of the patients was analysed with two-way analysis of variance (ANOVA) and the unpaired Student's t-test. Sensitivity, specificity, positive and negative predictive values, and 95% confidence interval (CI) values were calculated for the TOE results. Proportional changes within groups were determined by Pearson's {chi}2 analysis. A P value <0.05 was considered to be statistically significant.


    Results
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Complete data were recorded for all 62 patients. The patients in the cemented THA group were older and smaller than the patients in the non-cemented group. However, there were no differences in the characteristics including medical history of hypertension (P=1.000) and/or diabetes mellitus (P=0.557) between the patients with and without PE evaluated by PLS on POD1 (Table 1). TOE examination did not find any patients with intracardiac shunt in either group. Sequential changes in the values of the haemodynamic and respiratory parameters are presented in Table 2. Only the systolic blood pressure was higher in the cemented THA group than in the non-cemented group (P=0.014). None of the factors affected the occurrence of PE (Table 2). The patients did not present any severe clinical complications such as cyanosis, hypotension or disorder of eye opening, verbal response or motor response in the post-anaesthesia care unit. Only two patients with PE out of the 62 patients complained of mild dyspnoea and were treated with mask oxygenation until POD2.


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Table 1 Comparisons of the characteristics in two classifications of 62 patients.

 

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Table 2 Sequential changes of haemodynamic and respiratory parameters.

 
Echogenic changes, including variable grading levels of a snowstorm pattern on the background image and/or embolus, were observed during the surgical procedure in most of the patients in both groups. The most serious echogenic pattern frequently appeared when the hip joint was relocated after the insertion of the artificial stem. Each grading score for the TOE findings was greater in the cemented THA group than in the non-cemented group (Fig. 1). None of these graphical parameters was different between the two groups classified with the existence of PE (Fig. 1). PE was diagnosed in nine (15%; 95% CI 7–26%) of the 62 patients with THA by PLS on POD1, five (25%; 95% CI 9–49%) of the 20 patients who underwent cemented THA and four (10%; 95% CI 3–23%) of the 42 patients who underwent non-cemented THA. Sensitivity, specificity, and positive and negative predictive values of TOE findings for the development of PE on POD1 were 0.78 (0.40–0.97), 0.60 (0.46–0.74), 0.25 (0.11–0.45) and 0.94 (0.80–0.99), respectively. The odds ratio for positive findings of TOE on the occurrence of PE was 5.3 (1.01–28.2).



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Fig 1 (A and B) Amount of echogenic particles in right atrium (RA); (C and D) the longest time of echogenisis during surgery; (E and F) diameter of the largest echogenic particles. These graphical parameters were significantly different between the cemented and non-cemented THA groups. However, none of these graphical parameters affected the frequency of pulmonary embolism on the first postoperative day. Pearson's {chi}2-analysis was used for comparisons between groups.

 

    Discussion
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
TOE could identify the embolic events during THA. However, TOE findings did not predict the occurrence of PE on POD1. The sensitivity, specificity, and positive predictive values for the detection of echogenic macroemboli were low for the development of PE on POD1. PLS examination revealed a high frequency of development of PE on POD1, although the symptoms were subclinical. Therefore early treatment, including infusion of low-molecular-weight heparin, might be desirable immediately after or even before accomplishment of haemostasis6 even in patients in whom no echogenic macroemboli were detected.

There are several limitations on the interpretation of the results in this study. PE was diagnosed only by PLS examination rather than ventilation–perfusion lung scanning or pulmonary angiography, which is recognized as the gold standard. Even though the sensitivity of the ventilation–perfusion scan was reported as 98%, its specificity was only 10% in a previous study using ventilation–perfusion lung scanning.8 A prospective investigative study of acute PE diagnosis confirmed the value of PLS without the ventilation scan in the diagnosis of PE.9 The PLS examination was considerably superior for the detection of massive defects, but not for finding diffuse defects in the pulmonary vasculature. A snowstorm image was frequently observed by intraoperative TOE in patients who underwent THA with bone cement.12 14 In these patients, the pattern of PE was assumed to be diffused into the whole pulmonary vasculature. Therefore our results with PLS might have underestimated the frequency of PE in patients with snowstorm images during the surgical THA procedure.

TOE examination might also have a limitation for the evaluation of the echogenic events flowing from the lower leg. The TOE only detected changes in ultrasound reflection caused by substances, such as bone marrow, fat or thrombus, floating in the bloodstream or possibly by changes of temperature in the bloodstream during bone cementation because the polymerization of the acrylic monomer produces temperatures >80°C. The echogenic macroemboli might also be aggregates of small echogenic particles. Therefore the results of TOE examination may have overestimated the diameter of the largest particle, which could cause a low sensitivity, a low specificity and a low positive predictive value of the echogenic macroembolism for PE development on POD1 in this study.

We investigated the direct relationship between the occurrence of intraoperative macroemboli and the formation of subsequent PE. However, PLS was performed on POD1 because of the institutional rules regarding routine examination. Postoperative hypercoagulability was reported following THA,11 and the echogenic emboli, particularly where bone cement was used, might cause endothelial damage17 in the pulmonary vasculature which could produce secondary thrombi. Therefore our results could not exclude the possibility of PE formation during the first night before PLS examination in some cases.

If large or serpentine emboli consisting of hard blood clots, such as DVT, clogged the large pulmonary vasculature, it would cause severe right heart failure including sudden cardiac arrest.2 3 However, the clinical symptoms of our patients were much milder than we expected from the size of echogenic emboli observed during the surgery. Video images suggested that the large or serpentine emboli were soft or fragile, and might have consisted of either fat and/or fresh thrombus. Such soft or fragile emboli could be broken into pieces by heartbeats or the whirl of the bloodstream at the branch of pulmonary vasculature and cause mainly peripheral occlusion. Thus the mild clinical symptoms with large emboli might be explained by differences between the large pulmonary capillary volume and the relatively small embolic mass.

Large emboli were seen in some patients by TOE, but PLS did not always detect PE in patients with echogenic emboli. The inconsistency of the relationship between TOE findings and PLS results raised doubts about whether echogenic emboli directly caused PE on POD1. Human and animal studies have reported that pulmonary artery pressure transiently increased after cement implantation.18 19 Furthermore, the difference between and the partial pressure of carbon dioxide in the arterial blood became small within 15 min after the restoration of the hip joint.12 14 Fibrinolysis was believed to be activated following surgical stimulation and could dissolve thrombi clogged in the pulmonary vasculature.20 Transpulmonary passage of fat might also account for the relatively low frequency of PE in these patients.21 Further investigations will be needed to determine the components of echogenic emboli and the mechanism of PE formation.

In conclusion, intraoperative TOE monitoring did not predict the occurrence of PE on POD1, although PLS examination revealed a high frequency of development of subclinical PE on POD1.


    References
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
1 Parvizi J, Johnson BG, Rowland C et al. Thirty-day mortality after elective total hip arthroplasty. J Bone Joint Surg Am 2001; 83: 1524–8[Abstract/Free Full Text]

2 Patterson BM, Healey JH, Cornell CN, Sharrock NE. Cardiac arrest during hip arthroplasty with a cemented long-stem component. A report of seven cases. J Bone Joint Surg Am 1991; 73: 271–7[Abstract]

3 Fallon KM, Fuller JG, Morley-Forster P. Fat embolization and fatal cardiac arrest during hip arthroplasty with methylmethacrylate. Can J Anaesth 2001; 48: 626–9[Abstract/Free Full Text]

4 Fitzgerald R, Mason L, Kanumilli V et al. Transient cardiac standstill associated with embolic phenomena diagnosed by intraoperative transesophageal echocardiography during cemented total hip arthroplasty. Anesth Analg 1994; 79: 382–5[ISI][Medline]

5 Propst JW, Siegel LC, Schnittger I et al. Segmental wall motion abnormalities in patients undergoing total hip replacement: correlations with intraoperative events. Anesth Analg 1993; 77: 743–9[Abstract]

6 Hull RD, Pineo GF, Francis C et al. Low-molecular-weight heparin prophylaxis using dalteparin extended out-of-hospital vs in-hospital warfarin/out-of-hospital placebo in hip arthroplasty patients: a double-blind, randomized comparison. The North American Fragmin Trial Investigators. Arch Intern Med 2000; 160: 2208–15[Abstract/Free Full Text]

7 Eriksson BI, Bergqvist D, Kalebo P et al. Ximelagatran and melagatran compared with dalteparin for prevention of venous thromboembolism after total hip or knee replacement: the METHRO II randomized trial. Lancet 2002; 360: 1441–7[CrossRef][ISI][Medline]

8 The PIOPED Investigators. Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). JAMA 1990; 263: 2753–9[Abstract]

9 Miniati M, Pistolesi M, Marini C et al. Value of perfusion lung scan in the diagnosis of pulmonary embolism: results of the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED). Am J Respir Crit Care Med 1996; 154: 1387–93[Abstract]

10 Rose PS, Punjabi NM, Pearse DB. Treatment of right heart thromboemboli. Chest 2002; 121: 806–14[Abstract/Free Full Text]

11 Dahl OE, Aspelin T, Arnesen H et al. Increased activation of coagulation and formation of late deep venous thrombosis following discontinuation of thromboprophylaxis after hip replacement surgery. Thromb Res 1995; 80: 299–306[CrossRef][ISI][Medline]

12 Ereth MH, Weber JG, Abel MD et al. Cemented versus noncemented total hip arthroplasty—embolism, hemodynamics, and intrapulmonary shunting. Mayo Clin Proc 1992; 67: 1066–74[ISI][Medline]

13 Lafont ND, Kalonji MK, Barre J et al. Clinical features and echocardiography of embolism during cemented hip arthroplasty. Can J Anaesth 1997; 44: 112–17[Abstract]

14 Koessler MJ, Fabiani R, Hamer H, Pitto RP. The clinical relevance of embolic events detected by transesophageal echocardiography during cemented total hip arthroplasty: a randomized clinical trial. Anesth Analg 2001; 92: 49–55[Abstract/Free Full Text]

15 Orsini EC, Byrick RJ, Mullen JB et al. Cardiopulmonary function and pulmonary microemboli during arthroplasty using cemented or non-cemented components. The role of intramedullary pressure. J Bone Joint Surg Am 1987; 69: 822–32[Abstract]

16 Stein PD, Athanasoulis C, Alavi A et al. Complications and validity of pulmonary angiography in acute pulmonary embolism. Circulation 1992; 85: 462–8[Abstract]

17 Dahl OE, Westvik AB, Kierulf P, Lyberg T. Effect of monomethylmethacrylate on procoagulant activities of human monocytes and umbilical vein endothelial cells in vitro. Thromb Res 1994; 74: 377–87[CrossRef][ISI][Medline]

18 Murphy P, Edelist G, Byrick RJ et al. Relationship of fat embolism to haemodynamic and echocardiographic changes during cemented arthroplasty. Can J Anaesth 1997; 44: 1293–300[Abstract]

19 Dahl OE. The role of the pulmonary circulation in the regulation of coagulation and fibrinolysis in relation to major surgery. J Cardiothorac Vasc Anesth 1997; 11: 322–8[CrossRef][ISI][Medline]

20 Dahl OE, Pedersen T, Kierulf P et al. Sequential intrapulmonary and systemic activation of coagulation and fibrinolysis during and after total hip replacement surgery. Thromb Res 1993; 70: 451–8[CrossRef][ISI][Medline]

21 Byrick RJ, Mullen JB, Mazer CD, Guest CB. Transpulmonary systemic fat embolism. Studies in mongrel dogs after cemented arthroplasty. Am J Respir Crit Care Med 1994; 150: 1416–22[Abstract]





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