The Effects of CO2 Pneumoperitoneum at Different Temperature and Humidity on Hemodynamic and Respiratory Parameters and Postoperative Pain in Gynecological Laparoscopic Surgery: A Prospective Randomized Controlled Study
Phase: NA
Conditions: Benign Neoplasm of Cervix Uteri, Gynecological Laparoscopy
Sponsor: Ege University

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The effects of CO2 pneumoperitoneum at different temperature and humidity on 
hemodynamic and respiratory parameters and postoperative pain in gynecological 
laparoscopic surgery: A Prospective Randomized Controlled Study 
 
 
Document Date: April  17, 2019 
NCT: 04508387 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Abstract 
Objective: It is recommended to heat and humidify CO2 in laparoscopic surgery to prevent 
postoperative pain and hypothermia but information about its effects on hemodynamic and 
respiratory parameters is limited. We aimed to investigate the effects of standard and heated-
humidified CO2 on hemodynamic and respiratory parameters.   
Study design: One hundred patients who underwent laparoscopic hysterectomy for benign 
pathology were divided into two groups: Group CD (cold-dry) patients were administered 
standard CO2, while Group HH (heated-humidified) patients were administered 95% 
humidified insufflation at 37°C. Hemodynamic and respiratory parameters, body temperature, 
pain score and blood count parameters were  recorded. 
Results: A total of 96 patients were included in the study, taken from the 100 patients. Group 
HH (n:47) had only higher systolic blood pressure at 75 min, mean blood pressure at 50 and 
55 min and a lower heart rate between 15 and 45 min (p:0.049, 0.037, 0.013 respectively). 
Pain score, morphine consumption, end-tidal CO2 and arterial blood gas values were not 
different between the groups, with only body temperature from 40 min and minimum value 
being significantly higher (at a difference of 0.86-1.04°C) in Group HH. Postoperative 
leukocyte, neutrophil and NLR (neutrophil-leukocyte ratio) were found to be higher in this 
group (p<0.05).  
Conclusion: It has been found that both standard and heated-humidified CO2 do not constitute 
a problem in terms of hemodynamic and respiratory parameters. However, the standard CO2 
group had a lower core body temperature and inflammatory response.  
Keywords: Gynecological laparoscopy, standard CO2, heated-humidified CO2, hemodynamic, 
respiratory parameters 
 
 
 
 
 
 
 
 
 
 

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Introduction  
Laparoscopy surgery has been associated with less postoperative pain, less systemic immunological 
depression, less wound infection, shorter hospital stays and earlier return to normal activities; however, 
the hemodynamic changes caused by pneumoperitoneum, patient's position and hypercarbia have 
always been a concern for surgeon and anesthesiologists. Hypercarbia and increased intraabdominal 
pressure affect cardiac output, central venous pressure, heart rate (HR), mean blood pressure (MBP) and 
systemic vascular resistance through various mechanisms in laparoscopic surgery. The hemodynamic 
effects of mild hypercarbia are less serious than the mechanical effects of increased intraperitoneal 
pressure, although moderate and severe hypercarbia lead to significant hemodynamic changes, both 
directly by the cardiovascular system and indirectly by the autonomic system. Its effects on the 
sympathetic nervous system cause increased blood pressure, heart rate and risk of arrhythmia. 
Especially, patients with cardiac or pulmonary diseases are at increased risk because of reduced cardiac 
output, increased central venous pressure, respiratory pressure and acidosis [1-4].  
Standard carbon dioxide (CO2) is often preferred at room temperature (20–25°C) and dry (at 0-5% 
relative humidity) in laparoscopic surgery [5,6]. Recent years have witnessed devices that provide heat 
(35-37°C) and humidity (95-98%) to prevent postoperative pain and intraoperative hypothermia. 
However, the number of studies on the effects of heated CO2 on hemodynamic and respiratory 
parameters is limited [7-9], and these studies do not include humidified CO2. We aimed to test whether 
heated (37°C)-humidified (95%) CO2 would diffuse more easily into the blood from the abdomen and 
cause more hypercarbia compared to standard CO2 in cases with constant intraabdominal pressure and 
whether it would affect hemodynamic, given the vasodilation that could occur, and respiratory 
parameters.  
Although laparoscopy surgery is known to cause less systemic inflammation, some studies have 
reported that the use of standard CO2 during laparoscopy led to a higher local or systemic inflammatory 
response compared to heated-humidified CO2. This response has been stated to be particularly due to 
drying and damage in the peritoneum and has been associated with postoperative pain [4,5,10]. The 
second aim of this study was to examine simple indicators of inflammation, i.e., leukocyte and their 
subtype (neutrophil and lymphocyte counts) and neutrophil-lymphocyte ratios (NLRs) [11-14] in 
standard CO2 and heated-humidified CO2 and to evaluate their correlation with postoperative pain., and 
to evaluate their correlation with postoperative pain.  
Materials and Methods 
After approval of Ethics Committee (19-3.1/40, 17.04.2019), written informed consent was obtained 
from patients. The sample consisted of 100 American Society of Anesthesiologists (ASA) physical 
status I-II patients aged 40-65 who underwent laparoscopic hysterectomy for benign pathology. Patients 
with chronic obstructive pulmonary disease, asthma, advanced liver and kidney disease, infection, 

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bleeding disorder and drug allergies were excluded. The patients were divided into two groups 
according to a randomization scheme created by a computer: Group CD (cold-dry) patients were 
administered dry CO2 via insufflator (Electronic CO2 Endoflator SCB, Karl Storz, Germany) at room 
temperature (21°C), while Group HH (heated-humidified) patients were administered 95% humidified 
CO2 insufflation (Endoflator 50, Karl Storz, Germany) at 37°C. The study was planned as a randomized 
and double-blind study, where patients were not informed of their group. During the operation and in 
the postoperative period, the patients were followed up by two different anesthetists. All patients were 
given information and training on the anesthesia method, the use of the patient-controlled-analgesia 
(PCA) device (Abbott Laboratories, USA) and the visual analog scale (VAS) the day before the 
operation. The patients' demographic data (age, weight, height, etc.) and their basal systolic, diastolic 
and mean blood pressures and heart rates were measured prior to the operation and recorded on the case 
report form.