Eur J Cardiothorac Surg 2007;31:711-713. doi:10.1016/j.ejcts.2007.01.019
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
The sequence of vessel interruption during lobectomy — does it affect the amount of blood retained in the lobe?
Alon Yellinb,*,
Siegal Sadetzkia,
David A Simanskyb,
Yael Refaelyb,
Angela Chetrita,
Michael Paleyb
a The Cancer Epidemiology Unit, The Gertner Institute, Sheba Medical Center, Tel Hashomer, and the Sackler Faculty of Medicine, Tel Aviv University, Israel
b Department of Thoracic Surgery, Sheba Medical Center, Tel Hashomer, and the Sackler Faculty of Medicine, Tel Aviv University, Israel
Received 6 September 2006;
received in revised form 20 December 2006;
accepted 15 January 2007.
* Corresponding author. Address: Department of Thoracic Surgery, Sheba Medical Center, Tel Hashomer 52621, Israel. Tel.: +972 3 5302723; Fax: +972 3 5354305. (Email: ayellin{at}sheba.health.gov.il).
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Abstract
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Objective: In a previous study, we have shown that the sequence of vessel interruption (SVI) during lobectomy has no impact on tumor recurrence. The aim of the present study was to determine whether SVI has an impact on the amount of blood retained in the resected lobe. Patients and methods: A non-randomized prospective study including 30 patients undergoing lobectomy for neoplasms. Group A-1'st had all lobar arteries ligated before interruption of the lobar vein and group V-1'st had a reverse sequence. Generous exclusion criteria were used, so as to include only patients with straightforward lobectomy, attempting to isolate SVI as the only factor that could affect blood loss. Lobar weight was recorded immediately after lobectomy. All ligatures and staplers were removed; blood drained from the lobe, collected and measured, and thereafter the lobe was weighed again. Results: Sixteen patients entered group A-1'st and 14 group V-1'st. The groups were similar in age, sex, body surface, histology, prior therapy, stage, FEV1%, length of operation, and number of segments resected. The amount of blood drained from the lobe was 31.4 ± 13 and 34.2 ± 14.8 ml in group A-1'st and V-1'st, respectively. The lobar weights before and after blood drainage were 177.6 ± 56.9, 141.7 ± 49.1 g and 201.5 ± 74.2, 161.6 ± 69.7 g, respectively. The amount of blood divided to the lobar weight was 0.178 ± 0.052 in group A-1'st and 0.177 ± 0.099 in group V-1'st. All of these figures did not differ statistically. No patient required blood transfusion during or after surgery. Conclusions: In straightforward lobectomy the amount of blood retained in the resected lobe is small. This amount is not affected by the sequence of hilar vessel interruption.
Key Words: Lobectomy • Vessel interruption • Sequence • Blood loss
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1. Introduction
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Surgery and complete removal of the primary tumor and its involved lymph nodes remains the most effective treatment for patients with limited lung cancer [1]. The basic technique for lobectomy, the most common type of resection, did not change since the 1940s when individual hilar dissection evolved [2,3]. During the years, there were changing fashions regarding the sequence of vessel interruption (lobar veins first and arteries to be followed or vice versa). Today's standpoint is much more liberal and the recommendation is that the order of vessel dissection and division will be according to the surgeon's preference [4]. Nevertheless, most surgeons interrupt the lobar vein first (V-1'st) believing that manipulation of the lung during operation can produce spillage of tumor cells into the circulation and seeding of micrometastasis to distant organs. In a recent study we suggested that the sequence of vessel interruption has no bearing on tumor recurrence [5]. Lobar artery interruption first (A-1'st) may, on the other hand, have a theoretical advantage in preventing unnecessary blood loss since the pulmonary blood supply to the lobe is immediately ceased. This claim was rejected by Miller et al. [6] in an animal study. Suprisingly, it was never evaluated in human patients undergoing lung resection.
The aim of the present study was to examine whether the sequence of vessel interruption during lobectomy has any effect on the amount of blood retained in the resected lobe.
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2. Patients and methods
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2.1 Inclusion and exclusion criteria
The study was performed prospectively in a nonrandomized fashion in one medical center since May 2001–October 2003. The order of vessel interruption was chosen by the performing surgeon according to his preference. Inclusion criterion was ‘clean’ simple lobectomy performed with the lung collapsed throughout the entire procedure. For this purpose double-lumen endotracheal tubes were routinely used. Exclusion criterion included any complex lobectomy (bilobectomy, or additional en bloc resection including chest wall, pericardium, diaphragm, or wedge of another lobe, or sleeve lobectomy, or intraoperative biopsy of the resected lobe), meaningful adhesions, technical problems (bleeding during fissure separation, slipped ligatures, or failure to maintain the lung in a collapsed state), inflammatory conditions, and post-obstructive pneumonitis. Middle lobectomy was also excluded due to the small size of this lobe and the fact that all of these procedures are much more easy to do with V-1'st. Patients who had a mixed sequence of vessel interruption were not included. Thus, any deviation from the strict definition of a ‘clean’ simple lobectomy was a reason for exclusion.
2.2 Study methods
During lobectomy, all vessels were secured on both sides before they were cut. In cases of A-1'st, all arteries were ligated and divided before occlusion of the lobar vein. Fissures were separated in a manner preventing bleeding. The lobe was immediately removed to a side tray and weighed (crude weight). All ligatures and clips were removed and the blood was allowed to drain out. The lobe was than weighed again (dry weight) and simultaneously the amount of blood measured.
The data recorded on-line were: patient's age and gender, condition leading to surgery, date, body surface, FEV1%, type of incision, type of lobe resected, order of interruption, performing surgeon, length of operation, tumor size, and intraoperative blood transfusion. Postoperatively, the exact histology and stage were recorded, as well as the need for transfusion and morbidity. All the information was fed to a database. We calculated ‘adjusted lobar weight’ by dividing crude weight to body area. We also calculated ‘specific blood loss’ by dividing the amount of blood retained in the lobe to the crude lobar weight.
2.3 Statistics
Comparison of the distribution of age and clinical characteristics between the two study groups was assessed by chi-square test or Fisher's exact test. Age and blood parameters across the two methods were evaluated by t-test. The p-value of <0.05 was considered significant and 0.05–0.1 as borderline significant.
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3. Results
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3.1 Patient selection
During the study period 144 patients underwent lobectomy for various conditions. One hundred and fourteen patients were excluded due to complex lobectomy (n
= 21), intraoperative biopsy (n
= 35), middle (n
= 7) or bilobectomy (n
= 10), inflammatory conditions (n
= 11), meaningful adhesions (n
= 7), mixed order of vessel interruption (n
= 6), technical problems (n
= 10), and logistic preparations (n
= 7). Thirty of them met the pre- and intraoperative strict inclusion criteria. Sixteen were in the A-1'st group and 14 in the V-1'st group. The data pertinent to the two groups are summarized in Table 1
. The groups were similar in most preoperative and intraoperative variables. There was a borderline significant difference related to the surgeons’ preference of which vessels to interrupt first.
3.2 Surgical results
Blood transfusion was not required in any patient. All patients were extubated immediately at the end of the procedure and were transferred to the floor. There was one perioperative mortality (3.3%) from pneumonia leading to respiratory failure. Morbidity consisted of two cases of atrial fibrillation (6.7%) and one case of prolonged air leak (3.3%).
3.3 Study results
Patients in the V-1'st group had a slightly higher crude, dry, and ‘adjusted’ lobar weight than those in the A-1'st group (Table 2
). The amount of blood retained in the resected lobe was very small and similar in both groups – averaging less than 35 ml. The specific blood loss was identical (p
= 0.9).
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4. Discussion
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The sequence of vessels interruption (SVI) during resection for lung malignancy may hypothetically affect the outcome. Although the amount of tumor cells shed to the blood stream when the veins are interrupted as the initial step of lobectomy, or pneumonectomy, is smaller compared to their amount when the vein is still patent [7], this probably does not have any bearing on tumor recurrence and tumor-related mortality [5]. One of the concerns that was expressed in the early days of VATS lobectomy was related to long-term results. Those could have been adversely affected also by increased parenchymal manipulation during surgery and an unconventional sequence of hilar vessel interruption. The results reported in some recent studies have largely calmed most of these concerns [8].
Because blood transfusion during lung resection may have a negative prognostic effect [9,10], the question whether SVI is related to blood loss is important. In this study, we have shown that the amount of blood retained in resected lobe is minute (<35 ml) regardless of the SVI. We have also failed to demonstrate any difference in the amount of retained blood whether arterial or venous circulation was interrupted first. Although these results are pertinent to the optimal conditions practiced along this study, there is no reason to believe that it should be different for most lobectomies and pneumonectomies as well, unless surgical technique is violated. The data presented here may be of special interest to surgeons practicing VATS lobectomy. This procedure is usually performed in patients similar to those included in our study and the lobar vessels are generally interrupted on a ‘first-come’ basis. Thus surgeons could feel comfortable to ignore the ‘historic’ SVI, having the assurance that neither tumor recurrence nor blood loss is affected. Indeed, McKenna et al. [11] have recently shown that transfusion requirement during VATS lobectomy may be as low as 4.1%.
There are some limitations to our study. The number of cases included is relatively small. Only simple ‘clean’ lobectomies were included, while in more complex lobectomies the amount of blood retained in the parenchyma might be higher. This may especially pertain to inflammatory conditions where a larger fraction of the inflow may be derived from the bronchial circulation. Although the study was prospective, there was no randomization. This led to a bias related to operator preference. Nevertheless, because the amount of blood retained in the lobe could be related to the SVI, but not to the surgeon, we do not believe that this factor had any effect on the results. It is possible that not all blood retained in the resected lobe was completely drained out. If this indeed occurred, there is no reason to assume that this additional amount would have differed among the groups.
Other factors may hypothetically affect the amount of blood retained in a resected lobe. It was shown that induced lung collapse causes ipsilateral hypoxic vasoconstriction [12,13] and that this could be affected by several anesthetic agents. In our study, we used the same anesthetic technique in all patients and excluded patients in whom the operated lung failed to remain collapsed throughout the entire procedure. There is evidence that advanced COPD modifies hypoxic vasoconstriction [14]. Patients included in the present evaluation had a wide range of pulmonary functions, but no patient had pulmonary hypertension. The FEV1% in A-1'st and V-1'st groups were 59–111 (median, 93) and 45–125 (median, 88), respectively, with an almost identical mean (p
= 0.9). Thus, we feel that COPD did not play a role in our study. Theoretically, the length of operation in general and the time interval from arterial to venous interruption (and vice versa) in particular could have an impact on the amount of blood retained in the resected lobe. Operation duration was similar in both groups studied by us. Due to anatomical considerations, the interval of vessel interruption is obviously longer (although this was not recorded) for the V-1'st SVI. Nevertheless, this did not result in an increased amount of blood retention in the lobe. We assume that the effect of hypoxic vasoconstriction negated its occurrence.
The present study failed to demonstrate differences in the amount of blood retained in a resected lobe regardless of the sequence of hilar vessel interruption. In simple ‘clean’ lobectomies, this amount is very small. The results presented here support the practice that hilar vessels could be interrupted in any sequence preferred by the surgeon.
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Footnotes
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\#9734; Presented at the joint 20th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 14th Annual Meeting of the European Society of Thoracic Surgeons, Stockholm, Sweden, September 10–13, 2006.
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Abstract
1. Introduction
