How Soon Should Drainage Tubes Be Removed After Cardiac Operations?

How Soon Should Drainage Tubes Be Removed After Cardiac Operations? Yvo M. Smulders, MD, Marco E. Wiepking, MD, Adrian C. Moulijn, MD, PhD, Jacques J. Koolen, MD, PhD, Harry B. van Wezel, MD, PhD, and Cees A. Visser, MD, PhD Departments of Cardiopulmonary Surgery, Anesthesiology, and Cardiology, University of Amsterdam, Academic Medical Center, Amsterdam, the Netherlands

Pericardial effusion frequently occurs after cardiac operation. Despite its high incidence, the etiological process of postoperative pericardial effusion remains unclear. Residual blood or thrombus has often been suggested as a possible cause, implying that the occurrence of pericardial effusion could be related to the effectiveness of postoperative thoracic drainage. This possible relationship, however, has never been studied. We found that prolonging the duration of thoracic drainage by 24 hours often increases total chest tube output considerably but does not affect the incidence of postoperative pericardial

effusion: approximately 55% of 100 patients in this study were shown by two-dimensional echocardiography to have pericardial effusion on the sixth postoperative day, regardless of the duration of postoperative drainage. Because of this, and because a long period of drainage causes discomfort for the patient, mechanical irritation to the heart and the pericardium, and an increased risk of infection, we recommend removing drains as soon as their efficacy has peaked, preferably on the first postoperative day. (Ann Thorac Surg 1989;48:540-3)

P

tion of drainage is related to incidence of postoperative pericardial effusion and thereby to contribute to establishment of clear criteria for drain removal.

ericardial effusion (PE) frequently occurs after cardiac operations [14] and may cause hemodynamic embarrassment and, if chronic, prolong hospitalization. Progression of PE to tamponade, although rare [5-71, is a much feared complication after cardiac operations. Although no consensus exists regarding the etiological process of PE, several groups of investigators have suggested that residual blood or thrombus in the pericardial space may be important factors [3, 7, 81. Therefore, adequate removal of blood from the pericardial sac and the mediastinum after operation by drainage may be essential in attempting to restrain the process of PE. To accomplish adequate drainage, chest tubes must be properly placed and their patency must be ensured, and the tubes must remain in place for a sufficient amount of time. Thus, removing chest tubes too early may result in avoidable postoperative complications. However, a long period of drainage is known to cause discomfort for the patient, mechanical irritation to the heart and pericardium, and an increased risk of infection [9, 101. A review of the literature showed that standard criteria to determine the moment when drains should be removed have not been established. In our clinic, chest tubes are preferably removed on the first postoperative day if drainage has been 50 mL or less during the previous four hours. If this condition is not fulfilled on the first postoperative day, drains are removed on the second postoperative day or even later. The present study compared patients in two groups to determine whether duraAccepted for publication June 16, 1989 Address reprint requests to Dr Moulijn, Department of Cardiopulmonary Surgery, Academic Medical Center, Meibergdreef 9 1105 AZ, Amsterdam, the Netherlands.

0 1989 by The Society of Thoracic Surgeons

Material and Methods One hundred adult patients who underwent a cardiac operation at the Amsterdam Academic Medical Center between May and November 1988 were studied. This group consisted of 65 men and 35 women, ranging in age from 29 to 82 years (mean age, 62 f 10 years). Potential subjects were excluded if (1) they had undergone a previous cardiac operation, (2) they did not undergo routine anticoagulation therapy, (3) they had serious postoperative complications such as severe myocardial failure, or (4) their chest tubes could not be removed within 24 hours after the operation because of persisting drainage. Subjects were randomly assigned to one of the following treatment groups: group 1 (n = 50), in which chest tubes were removed according to our usual conditions within 24 hours after the operation, and group 2 (n = 50), in which all patients routinely would have had their chest tubes removed within 24 hours after operation, but an additional period of drainage was effected in each of them by removing the drains on the second postoperative day, about 24 hours after this normally would have been done. The operations performed in each group are shown in Table 1. Before cardiopulmonary bypass, heparin (2.5 mg/kg body weight) was administered to achieve an activated clotting time of at least 500 seconds. The effect of heparin was reversed by protamine sulfate. The cardiopulmonary bypass units were equipped with a Cobe CML-2 membrane oxygenator. The pump priming consisted of 0003-4975/89/$3.50

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SMULDERS ET AL POSTOPERATIVE DRAINAGE AND PERICARDIAL EFFUSION

Ann Thorac Surg 1989;48:540-3

Table 1. Surgical Procedures Performed in Both Treatment Groups

Table 2 . Incidence of Pericardial Effusion Compared With Duration of Postoperative Drainage

Procedure

Pericardial Effusion

CABG AVR

CABG

Group 2

None

24

Slight

17 9

21 17 12 0

Group 2

41

42

6

4

2

2

1

2

Moderate Heavy

+ AVR

Mitral valve replacement AVR = aortic valve replacement; grafting.

Group 1

Group 1

CABG

=

coronary artery bypass

Haemacel (1,500 mL), Ringer’s lactate (500 mL), mannitol 20% (100 mL), and sodium bicarbonate 8.4% (50 mL). Each patient had a 32F tube placed retrosternally and a second 28F tube placed posteriorly in the pericardial space. If one or both pleural spaces were opened, additional tubes were inserted. In most patients, the upper two thirds of the pericardium was closed at 2-cm intervals. Each tube was connected to a disposable water seal drainage system with 10 cm H,O suction. Chest tubes were frequently milked and stripped in the early postoperative period to ensure tube patency. Anticoagulation with Coumadin (crystalline warfarin sodium) derivates was started on the morning of the first postoperative day in all subjects. Dosages were such that the patients’ thrombotest attained a level between 5% and 15%. Subjects had not received anticoagulants before opera tion. To assess the presence and size of PE, two-dimensional echocardiography was performed on the sixth postoperative day. Pericardial effusion was classified as follows: (1) slight, fluid was localized only at and below the atrioventricular groove, or thin traces of fluid were seen anywhere between epicardium and pericardium; (2) moderate, a fairly uniform distribution of more fluid was seen posteriorly and apically (Fig 1);and (3) heavy, fluid was present posteriorly, apically, and anteriorly. Data were analyzed statistically by Student’s t test and

Fig I. Parasternal long-axis view at the level of the base of the heart showing an example of a moderate pericardial effusion (arrows). €flusions markedly heavier than the one shown were not observed in any of the patients. (Ao = aorta; LA = left atrium; LV = left ventricle; RV = right ventricle.)

0

Significance: ,$ = 0.63, p > 0.3.

the 2 test. A Pearson product-moment correlation coefficient (r) was calculated where appropriate. Data are represented as the mean 2 standard deviation. A p value of less than 0.05 was considered statistically significant.

Results Basic Drainage Period All 100 patients included in this study reached the point at which less than 50 mL was drained in a four-hour period within 24 hours after operation. (Thirty-one percent of all patients operated on during the study period who did not meet any of the three other exclusion criteria described had drainage persisting longer than this ”basic” period and were excluded for this reason.) Mean chest tube output during the basic period was 661 2 355 mL in patients without pleural chest tubes and 863 f 445 mL in patients with pleural chest tubes ( p < 0.02). Patients with aortic valve replacement alone or in combination with coronary bypass grafting demonstrated a significantly larger blood loss (860 ? 470 mL) during this period as compared with patients without aortic valve replacement (660 ? 357 mL) ( p < 0.05).

Additional Drainage Fifty patients had an additional 24-hour drainage period, which resulted in an increase in mean chest tube output. Output was also significantly greater in patients with pleural tubes (range, 0 to 355 mL; mean, 153 5 100) than in patients without pleural tubes (range, 0 to 225 mL; mean, 97 ? 60) ( p < 0.02). The large standard deviations reflect the striking variability associated with these values. The aspect of fluid drained in the additional period gradually became more serous in most patients. Statistical analysis showed that the amount of chest tube production in the additional period was not significantly correlated with blood loss in the basic period (r = 0.12, p > 0.3). Furthermore, additional chest drainage was not related to the patient’s age, sex, weight, and type of operation performed. The duration of cardiopulmonary bypass was compared with chest tube output and showed a trend toward a positive correlation with drainage in both the basic (r = 0.11) and the additional ( r = 0.22) drainage period. Neither trend, however, was statistically significant ( p > 0.15). Pericardial Effusion Table 2 shows the incidences of postoperative PE. Clearly, incidence of PE was generally not affected by differences

rew,,in portoperativedrainage.

The possible correlation of drainage with PE is twofold. First, when chest tubes are removed tw eartv. wnistent stow bleedine mav aawe

m duration of postoperative dramage. The effect of postoperative anticoagulation therapy, as measured with the thromb-ateet, had no correlation with the presence of PE. Purthem~ore, the incidence of portoperative PE appeared to be unrelated to the patient% age, sex, weight. or tyQe of operation or to the presence of tubes in the pleural spece. The possible in”uence of the amoont of chest drainage on PE was aleo evaluated. chest tobe output in the basic drainage pertort showed no correlation with PE on the sixth patopmt!\e day. Table 3 compares the incidence of PB with the amount of chest dreinage in the addttkmai period. The bss frequent occurrei;c~of PE in patients who had less than 60 mL of additional drain production proved ntatisticaliy significant. Delayed cardiac tamponade was nat observed in ai;y of the subjects. comment Several eehoardiomaohic studies have been undertaken to invest~gatcthe i&tdence of PE after cardiac operations. Reifart and colleagues 14, repaned an incidenrr of 26%. whereas other investigators found PE in over M% of operated patients 11-3). Writzman and colleagues 121had the hieh~st rewrted mddence: 85% of all oattents in their studykere fo;nd to have pastoperatiw Pis. The vartabilsty ~Weefi the* eet ma@ is p:obabty ptily hatred by certain pitfalls in the ultrasound diagnosis of PE. Isolated anterior echo-free spces can be espoct&ly difftcult to interpret, as often not PE but adipose tisrr!e or other matenat causes such spacer. Dewite the high incidence of effusion, arsociated delaycd &tiac tan&nade is P raw complication, occurring in O.gY. to 1.39. of all operated ~abents [5-q. However, hemodynamic effects may also be present when clinical signs of tamponade are not. intermediate effects of PE include an exaggeated insptratory decrease in left veritricular filling and ejection time and an abnormal imp&-atory increase in preeiection period Ill, Uj. The extent to which PE influences cardiovasccular physiology mainly depends on the amount of fluid, the elasticity of the pariehl pcricwlium, and the rate of fluid accumulation. Postoperative development of pericardial adhesions may also be a determinant, 1% it may cause locutatton of pericardiat tiuii lriih subsequent tampanade (KS]. Thus, complications of w+overative PE are WT, difbcolt to a&pate. The ceue.e of postoperative PE is most Likely multtfactw rial. Residual b&d or lysis of residual pericardial thmmbus has been suggested to cause effusion by irritating the pericexiiwn with hydrophilic action !7, g], which could

.

.

prolongtog the duration of chest drainage may pwvcx irritation and hydrophilic action. ‘Tbe best time to rc~z:e drh; :s diffticvlt to determine; eermanguineous dx innge eetdom ceases completely. infvmwtion regarding drainage pofky in poetoperative care *a6 obf&ed from ab !2 Dutch iardkw wrgezy clinics. Six of the,,, bad no spedfic nitena for production b&i-e drain removal. The criteria of those that did varied sub stantta:ty, ranging from M nab or tees fox three bmns to 4C mL ,f eight-hour period. In one clinic, ‘nest tubes were never re-rwd e;wlier than the second p&qent:i. Ay. The possible retatton~hip between the duration of pwtoperative drainage and the development of PE has never hn studied. 0ne study reveals that pmlongfng the duration of cbeest drainage by 24 bourn can increase L?Mlage of mostly seroeangubnous C”id aub:.mtldy, erpe&uy in patients in whom pleul?’ h>bes l*’ inserted. The tatter IS a rwong indication that the aAiidomd output is at least partly gauged 5j the ptrsettce of the ches! tubes themselves, as the pleara is very euecepttbte to mecbanicat irritation. The great variability In additionat chest tube output, however, suggests that more factors are involved. Our efforts to exphh why some patients Ilaw more than 2UOml. of additional chest tube outout whereas others produce practically nothing were u&ce&l. No variabtes significantly influenced additional chest tobe output. A particular. the amount of “early” postoperative dmbv age had no predictive value. In 10,:. treatment PIL”DS. the inddenoe of PE on the

totalourput in an

in&ences of p&+ive PE were reported 11.31. None of the observed effisions was large, and no sub@ had severe humcdynamtc conequences of PE. Postoperative effusion was previoosty reported to occur more frequently im patients with large amounts of postoperative drainape 111. In this study, PE correlated with drainage In another way. The occurrence of PE war unrelated to blood loss in the basic dratnage period. However. patients who produced lees the” a mL in the extra X-bow’ period had PE significantly less frequently than did pstients with more then MI ml_ of additional drainage. This is an important ftwltng, indicating that in some patients the process leading to PE on the sixth postoperative day pmbably is already active on the first and sand postoperative day. There are several possible reasons why prolonged drainage does not case a decrease in frequency of pastoperative PR. Postoperative medtaetinat drainage, regardless ot its duration, never resuta in a comolete rvacoattori of fluid from the paicardial space [M].‘The umlrained fluids may cause irrttation or exert bydmpbtftc action or may themselves still be visible on echocardiography on the sixth postoperative&y. In addition, pos’q,emtive PE and cardiac tamponade have been suggested to correlate

Ann Thorac Surg 1989;48:54(M

w i t h use of anticoagulants [15, 161. That we routinely administer anticoagulants i n patients who have undergone coronary artery bypass grafting, which is not common i n the United States, may have had an effect on t h e overall incidence of PE i n b o t h groups. However, because C o u m a d i n therapy started on t h e first postoperative day takes considerable time to reach its full effect, we believe t h e results of our study regarding the effects of prolonging drainage a r e unrelated t o use of anticoagulants. Finally, traumatic and infectious pericarditis h a v e also been suggested as possible causes of PE unrelated to postoperative drainage. In summary, this s t u d y proves that prolonging postoperative thoracic drainage h a s no advantageous effect on the incidence of PE after a cardiac operation. We conclude t h a t d r a i n s generally c a n be removed safely on t h e first postoperative day, as soon as production is less t h a n 50 mL for four h o u r s or p e r h a p s even sooner. Removing chest tubes later unnecessarily increases t h e risk of infection [9, 101, mechanical irritation by t h e tubes, a n d discomfort to the patient. We thank C. L. A. Reichert, H. C. J. De Koning, and A. A. M. van Corler from the Division of Cardiology for their help in preparation and interpretation of the echocardiograms.

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