Role of Indexed Oxygen Delivery in Anastomotic Insufficiencies in Elective Laparoscopic Colorectal Resections for Cancer: a Prospective Observational Cohort Study
Conditions: Anastomosis; Complications, Anastomosis, Surgical, Anastomosis, Leaking, Anastomotic Leaks, Anastomotic Failure of Flap, Anastomotic Leak Large Intestine, Anastomotic Complication, Anastomotic Dehiscence in Colorectal Surgery, Anastomotic Leakage in Colon Surgery, Oxygen Delivery, Oxygen Delivery (DO2)
Sponsor: Saint Camillus International University of Health Sciences

 
 
 
 
 
 
 
 
 
 
 
Study Protocol + Statistical Analysis Plan (SAP) 
 
 
 
ROLE OF O2 AVAILABILITY IN ANASTOMOTIC LEAKAGE IN LAPAROSCOPIC 
COLORECTAL SURGERY FOR CANCER 
 
 
version I 7th June 2020 
Approved by local Ethics Committee on 23rd July 2020 
(Protocol n. 00154/2020) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Introduction 
Colorectal cancer is the third most commonly diagnosed cancer in the world. It accounts for 11% of 
all cancer diagnoses, and is the fourth leading cause of cancer mortality, with 1.8 million new cases 
and approximately 861,000 deaths in 2018 (GLOBOCAN CHI database). Surgical resection is the 
mainstay of therapy for patients with non-metastatic disease, and has a significant impact on the 
long-term survival of patients with metastatic disease (3). Outcome is closely related to the quality 
of preoperative staging, surgery, and multidisciplinary patient management (4-5). 
Anastomotic dehiscence (AD) is the most feared complication following resective colorectal 
surgery due to the high rate of morbidity and mortality that results from the worsening of the overall 
and oncological outcome of the patient and the increase in the time and costs of hospitalization (6). 
The International Study Group of Rectal Cancer has defined AD as “a communication between intra 
and extra luminal compartments due to a defect in the integrity of the intestinal wall at the 
anastomosis between intestinal segments” (7). In literature the mortality rate resulting from AD is 
very variable.  
An Australian study of 1,598 patients recorded a mortality rate of 1.7% (8), but other case studies 
report a higher percentage, up to 29%. (9-10-11). Approximately 1/3 of deaths following colorectal 
surgery are attributable to this complication (12). 
The incidence varies depending on the anatomical location of the anastomosis: 1-‐20% in the case 
of colorectal anastomosis; 0-‐2% in the case of colo-‐colic anastomosis and 0.02-‐4% in the case of 
ileo-‐colic anastomosis (13-‐14-‐15-‐16). Risk factors for anastomotic leakage can be divided into 
preoperative, intraoperative, and postoperative factors.  
All can be traced back to two main groups: local, related to the surgical technique, and general, 
related to the patient. As regards local factors, the most significant are: experience of the surgeon 
(especially in the case of laparoscopic surgery), distance from the anal margin, suturing of the 
anastomosis using manual or mechanical staples, type of anastomosis (lateral-‐to-‐side, end-‐to-‐
side, end-‐to-‐end), tension, vascularization and hemostasis of the anastomotic ends, presence of a 

protective stoma, placement of drains, bowel preparation, role of the microbiome (17). Review from 
2015 identified several patient-related modifiable and non-modifiable risk factors, including: male 
sex, smoking, habits, alcohol consumption, obesity, diabetes, vascular disease, use of anti - 
inflammatory drugs, transfusions, hypoalbuminemia, anemia, intraoperative hypotension and use of 
cardio-‐vascular drugs, neoadjuvant radiotherapy and chemotherapy(18). 
A factor that occurs in almost all these conditions is an alteration in tissue perfusion, and therefore 
in oxygen availability with consequent micro-‐ischemia of affected segments and failure of the 
anastomosis. 
Reduced availability of oxygen, in addition to the patient's condition, which can affect it both pre- 
and post-operatively, can also occur intraoperatively. Good tissue oxygenation can favorably 
influence the outcome of anastomoses. One study in fact has documented a reduction in the risk of 
AD following colorectal and gastric surgery with the administration of supplemental oxygen alone 
(FiO2 80%) during the procedure and for 6 hours thereafter (19). 
However, the availability of O2 is not determined exclusively by the inspiratory fraction of O2, but 
by factors present in the equation that defines the Oxygen Availability (DO2): 
 
 
DO2 =  CO x CaO2, where CaO2= (Hb  x SaO2  x 1,39) +  (0,0031 x PaO2) 
CO: Cardiac Output; CaO2: Arterial Oxygen content 
 
In this equation the portion of DO2 attributable to the dissolved form of O2 in arterial blood (PaO2) 
is negligible. Therefore the following equation can be considered: 
 
DO2 = CO x Hb x SaO2 x 1,39 
Considering all the parameters involved allows to have a more correct and complete idea of 
peripheral tissue perfusion. There is only one study in literature in which the indexed DO2 (DO2I) 
is put in relation to the incidence of AD (20). In this study the CO of 75 patients undergoing colonic 

resection was monitored via Doppler probe in the esophagus. The results show that patients with a 
DO2I <400 ml/min/m2 have a significantly higher risk of developing AD. 
The use of the esophageal Doppler probe for monitoring cardiac dynamics is, however, highly 
invasive and cannot ignore the operator's experience. Furthermore, it requires frequent checks of the 
correct positioning of the probe itself. It also presents some, albeit rare, contraindications. 
Currently, there are several methods for cardiovascular monitoring that allow obtaining sufficiently 
reliable hemodynamic data while being less or absent invasive and easy to interpret. Through  non-
invasive  analysis of the shape of peripheral blood waveform (pulse-‐contouring volume-‐clamp 
technique) by inflating a cuff placed on the patient's finger, it is possible to obtain complete 
information about volume status and preload, cardiac function and afterload, in an easily usable 
format (21-‐22). 
To calculate DO2I it is also necessary to know the patient's total hemoglobin (Hb) value, data 
obtainable with a blood test, normally performed preoperatively. However, during the surgical 
intervention, numerous factors contribute to modifying the Hb concentration, such as the patient's 
volume status and blood loss.  
To obtain reliable intraoperative data, it would therefore be necessary to resort to serial blood 
sampling, venous or arterial which is clearly invasive for the patient and an expenditure of 
economic resources. Currently, there are new-generation pulse oximeters on the market that analyze 
different wavelengths and simultaneously measure multiple parameters: O2 saturation, heart rate, 
respiratory rate, total hemoglobin, carboxyhemoglobin, and methemoglobin, arterial O2 content, 
perfusion index, and plethysmographic variability index. 
With this new technology it is therefore possible to obtain non-invasively and continuously more 
real and complete data, little influenced by patient movement and by conditions of low perfusion 
(23-‐24). 
 
Aim of the study 

To evaluate the effects of DO2I on the incidence of AD in patients undergoing laparoscopic 
resection for colorectal cancer. 
 
Materials and Methods 
Patients attending the General Surgery Unit of the S. Eugenio Hospital in Rome will be enrolled 
who meet the following inclusion criteria: 
‐age > 18 years 
-candidates for laparoscopic colorectal surgery in elective for neoplastic pathology 
Patients will be excluded if they meet the following criteria: 
-age <18 years 
‐inability to express valid informed consent 
-interventions that involve other areas of the body in addition to the colon and rectum 
-emergency interventions 
‐open surgical interventions 
‐patients who have contraindications to the use of the volume-‐clamp system for hemodynamic 
monitoring (conditions that alter significantly the perfusion of the fingers, e.g. Raynaud's disease) 
Each patient will follow a preoperative evaluation according to the clinical standards of the 
Anesthesia and Intensive Care Unit of the two recruiting centers: a complete physical examination 
will be conducted for all areas and a medical history aimed at identifying general and specific risk 
factors, and assigning a risk class of the American Society of Anesthesiologists (ASA). 
During the preoperative period a blood sample will be take for a complete blood count coagulation 
tests, and chemistry tests. 
All patients will be given a dedicated informed consent form which will explain the aims and 
methods of the study. Furthermore, all patients will be informed that the anesthesiological care is of 
equal intensity in each case, in accordance with the dictates of common and good clinical practice. 

Patients will be subjected to general anesthesia (GA) with titrated doses of propofol 1%, fentanyl, 
rocuronium, desflurane, oxygen, and air, with complete noninvasive monitoring. 
All enrolled patients will also be provided with non-invasive hemodynamic monitoring for the 
calculation of CO based on pulse‐contouring type volume clamp, via the ClearSight system 
(Edwards Lifescience Corporation-‐USA). Non-invasive monitoring will also be applied for oxygen 
calculation using pulse oximetry sensors Masimo rainbow (Masimo Corporation – Irvine, 
California). The DO2I will be calculated at three moments and periods during the procedure: 5 
minutes after the induction of GA, 30 minutes after the induction of pneumoperitoneum, 5 minutes 
after the end of pneumoperitoneum. This is intended to record the variation in DO2I in relation to 
the hemodynamic changes induced by pneumoperitoneum. 
All patients enrolled will constitute Group A. Based on the average of three measurements 
of DO2I obtained during the intervention, patients in Group A will be distributed into three 
subgroups: DO2I <400 ml/min/m2 (Group A1), DO2I 400-‐600 ml/min/m2 (Group A2), DO2I 
>600 ml/min/m2 (Group A3). The values of DO2I chosen as cut-offs for the formation of the three 
subgroups were established by analyzing the studies by Levy and by Shoemaker (20-‐25). 
For each of the three subgroups the incidence of AD will be calculated, also in relation to 
anamnestic risk factors. 
 
Statistical Analysis 
The data will be analyzed using the IBM SPSS software package (Armonk, NY), with calculation 
of medians and standard errors. For continuous variables, the t-test and ANOVA will be used. For 
categorical variables, the Fisher's exact test will be used. A p value < 0.05 will be considered 
statistically significant. 
 
 
 

Bibliography 
1. Bray F, Ferlay J, Soerjomataram I, et al. Global cancer statistics 2018: GLOBOCAN estimate of 
incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer Jlin. 2018;68:394–
424 
2. Ferlay J, Ervik M, Lam F, et al. Global Cancer Observatory: Cancer Today. Lyon, France: 
International Agency for Research on Cancer.  
3. Hermanek P, Wiebelt H, Riedl S, Staimmer D, Hermanek P. Long-‐term 
 results of surgical 
therapy of colon cancer. Results of the Colorectal Cancer Study Group (Article in German) Chirurg. 
1994;65:287–297 
4. Van de Velde CJH, et al. EURECCA colorectal: multidisciplinary management: Europea 
consensus conference colon & rectum. Eur J Cancer. 2014;50:1.e1–1.e34.  
5. Van de Velde CJH, et al. Experts reviews of the multidisciplinary consensus conference colon 
and rectal cancer 2012: science, opinion and experiences from the experts of surgery. Eur J Surg 
Oncol. 2014;40:454–68. Review of the EURECCA consensus on colorectal cancer surgery. 
6. Chadi SA, Fingerhut A, Berho M, DeMeester SR, Fleshman JW, Hyman NH, Margolin DA, 
Martz JE, McLemore EC, Molena D, Newman MI, Rafferty JF, Safar B, Senagore AJ, Zmora O, 
Wexner SD. Emerging Trends in the Etiology, Prevention, and Treatment of Gastrointestinal 
Anastomotic Leakage. J Gastrointest Surg 2016; 20: 2035-‐2051 
7.Rahbari NN, Weitz J, Hohenberger W, Heald RJ, Moran B, Ulrich A, Holm T, Wong WD, Tiret 
E, Moriya Y, Laurberg S (2010) Definition and grading of anastomotic leakage following interior 
resection of the rectum: a proposal by the International Study Group of Rectal Cancer. Surgery 
147(3):339–351 
8. Platell C, Barwood N, Dorfmann G, Makin G (2007) The incidence of anastomotic leaks in 
patients undergoing colorectal surgery. Color Dis 9(1):71–79.  
9. Buchs NC, Gervaz P, Secic M, Bucher P, Mugnier-‐Konrad B, Morel P (2008) Incidence, 
consequences, and risk factors for anastomotic dehiscence after colorectal surgery: a prospective 
monocentric study. Int J Color Dis 23(3):265–270 
10. Biondo S, Parés D, Kreisler E, Ragué JM, Fraccalvieri D, Ruiz AG, Jaurrieta E (2005) 
Anastomotic dehiscence after resection and primary anastomosis in left-‐sided colonic emergencies. 
Dis Colon Rectum 48(12):2272–2280 
11. Branagan G, Finnis D (2005) Prognosis after anastomotic leakage in colorectal surgery. Dis 
Colon Rectum 48(5):1021–1026 
12. Alberts JC, Parvaiz A, Moran BJ. Predicting risk and diminishing the consequences of 
anastomotic dehiscence following rectal resection. Colorectal Dis.2003;5:478-‐482 
13. Phitayakorn R, Delaney CP, Reynolds HL, Champagne BJ, Heriot June 7, 2018| Volume 24| 
Issue 21| AG, Neary P, Senagore AJ; International Anastomotic Leak Study Group. Standardized 
algorithms for  management of anastomotic leaks and related abdominal and pelvic abscesses after 
colorectal surgery. World J Surg 2008; 32: 1147-‐1156  
14. Hyman N, Manchester TL, Osler T, Burns B, Cataldo PA. Anastomotic leaks after intestinal 
anastomosis: it’s later  than you think. Ann Surg 2007; 245: 254-‐258 
15. Ito M, Sugito M, Kobayashi A, Nishizawa Y, Tsunoda Y, Saito N. Relationship between 
multiple numbers of stapler firings during rectal division and anastomotic leakage after 
laparoscopic rectal resection. Int J Colorectal Dis 2008; 23: 703-‐707 
16. Crafa F, Smolarek S, Missori G, Shalaby M, Quaresima S, Noviello A, Cassini D, Ascenzi P, 
Franceschilli L, Delrio P, Baldazzi G, Giampiero U, Megevand J, Maria Romano G, Sileri P. 
Transanal Inspection and Management of Low Colorectal Anastomosis Performed With  a New 
Technique: the TICRANT Study. Surg Innov 2017; 24: 483-‐491  
17. E.C. Zarnescu (Vasiliu), N.O. Zarnescu, R. Costea, S. Neagu: Review of Risk Factors for 
Anastomotic Leakage  in Colorectal Surgery Chirurgia (2015) 110: 319-‐326 No. 4, July -August 
18. Jeremy Meyer, Surennaidoo Naiken, Niki Christou, Emilie Liot, Christian Toso, Nicolas 

Christian Buchs, Frédéric Ris: Reducing anastomotic leak in colorectal surgery: The old dogmas 
and the new challenges. World J Gastroenterol 2019 September 14; 25(34): 5017-5025 
19. Schietroma M, Cecilia EM, Carlei F, Sista F, De Santis G, 
Piccione F, Amicucci G. 
Prevention of anastomotic leakage after total gastrectomy with perioperative supplemental oxygen 
administration a prospective randomized, double-‐blind, controlled, single-‐center  trial.  Ann Surg 
Oncol. 2013 May;20(5):1584-‐90.  
20. B. F. Levy, W. J. Fawcett, M. J. P. Scott and T. A. Rockall: Intra-‐operative oxygen  delivery in 
infusion volume-‐optimized patients undergoing laparoscopic 
 colorectal surgery within an 
enhanced recovery programme: the effect of different analgesic modalities. Colorectal Dis.July 
2012, Vol 4, Issue 7, Pages 887-‐892.  
21. Ameloot K, Palmers PJ, Malbrain ML. The accuracy of noninvasive cardiac output and pressure 
measurements with finger cuff: a concise review. Curr Opin Crit Care. 2015 Jun;21(3):232-‐9.  
22. Sangkum L, Liu GL, Yu L, Yan H, Kaye AD, Liu H. Minimally invasive or noninvasive cardiac 
output measurement: an update. J Anesth. 2016 Jun;30(3):461-80  
23. Colquhoun DA, Forkin KT, Durieux ME, Thiele RH, Ability of the Masimo pulse CO-‐
oximeter to detect changes in haemoglobin, J Clin Monit Comput. 2012 Apr;26(2):69-‐73 
24. Mendelson Y, Kent JC, Shahnarian A, Welch GW, Giasi RM, Evaluation of the Datascoper 
ACCUSAT pulse oximeter in healty adults. J Clin Monit. 1988 Jan;4(1):59-‐63. 
25. Shoemaker WC, Appel PL, Kram HB, Waxman K, Lee TS. Prospective trial of supranormal 
values of survivors as therapeutic goals in high-‐risk surgical patients. Chest 1988; 94: 1176–86