Surgical humidification

Laparoscopic surgery humidification

During laparoscopy (laparoscopic surgery or minimally invasive surgery), it is necessary to insufflate the abdominal cavity (i.e. inflate the abdomen like a balloon) with medical-grade carbon dioxide (CO2) to create a viewing and working space for the surgery. The CO2 may be unconditioned, or conditioned with heat, or with humidification and heat. During insufflation, the peritoneum (an extensive delicate membrane that lines the abdominal cavity and covers most of the abdominal organs) is exposed to the CO2.

Unconditioned medical-grade CO2 has virtually no moisture and enters the abdomen at room temperature (19 to 21 °C). The condition of the gas is dry and cold compared to that of the natural physiological state of the peritoneum which is immersed in fluid at body temperature (37 °C). Experimental and clinical investigations have demonstrated that insufflation with unconditioned CO2 causes evaporation of the fluid and drying of the peritoneum, resulting in inflammation and damage to its cells. Clinically, peritoneal injury caused by drying has been linked to post-operative pain, evaporative cooling resulting in a decrease in core temperature and increased risk of intra-operative hypothermia, as well as adhesion formation.

In addition, animal studies have revealed that surgical humidification reduces peritoneal tumor implantation and tumor load suggesting a possible benefit in cancer patients undergoing abdominal surgery.

Conditioning the CO2 with only heat causes tissue drying. Warmer gas has a greater capacity for evaporation as the gas can hold more water vapor, therefore the tissues will dry faster than when unconditioned gas is used, potentially leading to increased adverse consequences. Conditioning the CO2 with humidity, in combination with heat, has been shown to decrease peritoneal damage by reducing the capacity of CO2 to carry moisture away from the tissue. Temperature loss during surgery, due to tissue drying, can be prevented by adequately humidifying and heating the CO2.

Open (abdominal) surgery humidification

During open surgery the surgeon exposes the peritoneal cavity to the ambient air. Exposure to ambient air results in evaporation and cooling. Current studies have shown that the use of surgical humidification during open abdominal surgery (laparotomy) have warmer core body temperatures and reduced risk of operative hypothermia. As with any operation, maintaining patient normothermia is a critical process to prevent surgical site infections, additional respiratory distress and surgical bleeding.

Respiratory humidification during surgery

Anesthesia causes vasodilatation, which increases blood flow to the surface of the body and thus increases heat loss from the body. During anesthesia, blood flow to the surface may maintain skin temperature (which is normally lower than the core temperature), even while the core temperature is falling. Barring preventive interventions, hypothermia occurs in more than half of all surgical patients undergoing anesthesia.

The risk of a loss of body temperature and hypothermia increase with the duration of surgery, especially for surgery that lasts more than one hour. Surgical hypothermia, defined as a core temperature below 36.0 °C, is associated with increased risk of infectious and non-infections complications, longer post-operative ICU and overall hospital recovery, and more frequent requirement of transfusions. Elderly persons, especially those with lower muscle and body mass are at greater risk of hypothermia.

Respiratory humidification during surgery helps maintain body temperature and normal function of the respiratory mucosa. In the same way that some animals pant to lose excess body heat, heat is lost through the lungs during mechanical or assisted ventilation. Heated humidification of respiratory gases during surgery has been demonstrated to reduce the fall in core body temperature, especially in surgeries lasting longer than one hour. The lungs can be insufflated with respiratory gases that are heated to near body temperature and humidified to 90 to 100% relative humidity(RH). Normally, air in the lungs is at core body temperature and at close to 100% RH. Especially when cold dry gases (such as anhydrous compressed gas from oxygen tanks) are used, it cool and can dry the airway. The body then utilizes energy to evaporate sufficient water from the lungs to maintain lung gas temperature and humidity. It is generally estimated that 10 percent of the loss of body heat during surgery is from the respiratory tract. Especially in open surgery (rather than endoscopic/robotic surgery), respiratory humidification can be used in concert with forced air warming blankets or gowns, warmed IV, and irrigation fluids to prevent hypothermia.

References

References

1. United States Pharmacopoeia and the National Formulary Supplements. (2003)
2. Puttick, M. (1999). "Comparison of immunologic and physiologic effects of CO2 pneumoperitoneum at room and body temperatures". Surg Endosc.
3. Erikoglu, M. (2005). "Electron-microscopic alterations of the peritoneum after both cold and heated carbon dioxide pneumoperitoneum". J Surg Res.
4. Peng, Y. (2009). "Heated and humidified CO2 prevents hypothermia, peritoneal injury, and intra-abdominal adhesions during prolonged laparoscopic insufflations". J Surg Res.
5. Volz, J. (1999). "Characteristic alterations of the peritoneum after carbon dioxide pneumoperitoneum". Surg Endosc.
6. Mouton, W G. (1999). "Pain after laparoscopy". Surg Endosc.
7. Sajid, M. (2008). "Effect of heated and humidified carbon dioxide on patients after laparoscopic procedures: a meta-analysis". Surg Laparosc Endosc Percutan Tech.
8. Wills, VL. (2000). "Pain after laparoscopic cholecystectomy". Br J Surg.
9. Bessel, J. (1995). "Hypothermia induced by laparoscopic insufflation. A randomized study in a pig model.". Surg Endosc.
10. Bessell, J. (1999). "Humidified gas prevents hypothermia induced by laparoscopic insufflation: a randomized controlled study in a pig model". Surg Endosc.
11. Noll, E. (2012). "Heat loss during carbon dioxide insufflation: comparison of a nebulization based humidification device with a humidification and heating system". Surg Endosc.
12. Sammour, T. (2008). "Meta-analysis of the effect of warm humidified insufflation on pain after laparoscopy". Br J Surg.
13. Binda, M. (2006). "Effect of desiccation and temperature during laparoscopy on Adhesion formation in mice". Fertil Steril.
14. (2014-07-01). "Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model". Surgery Today.
15. (2015-12-01). "Peritoneal Tumorigenesis and Inflammation are Ameliorated by Humidified-Warm Carbon Dioxide Insufflation in the Mouse". Annals of Surgical Oncology.
16. (2013-01-01). "The effects of insufflation conditions on rat mesothelium". International Journal of Inflammation.
17. (2009-09-01). "Improved outcomes for lap-banding using the Insuflow device compared with heated-only gas". Journal of the Society of Laparoendoscopic Surgeons.
18. Bessel, J. (1998). "The Pathophysiology of Pneumoperitoneum".
19. Wills, V. (2001). "A randomized controlled trial assessing the effect of heated carbon dioxide for insufflation on pain and recovery after laparoscopic fundoplication". Surg Endoscopy.
20. (2002-10-01). "Impact of temperature and humidity of carbon dioxide pneumoperitoneum on body temperature and peritoneal morphology". Journal of Laparoendoscopic & Advanced Surgical Techniques. Part A.
21. (2012-11-01). "Local insufflation of warm humidified CO₂increases open wound and core temperature during open colon surgery: a randomized clinical trial". Anesthesia and Analgesia.
22. (2012-11-01). "Intraoperative local insufflation of warmed humidified CO₂ increases open wound and core temperatures: a randomized clinical trial". World Journal of Surgery.
23. (2015-06-01). "Association of Perioperative Hypothermia During Colectomy With Surgical Site Infection". JAMA Surgery.
24. (2008-01-01). "The effects of mild perioperative hypothermia on blood loss and transfusion requirement". Anesthesiology.
25. Hyungseok Seo. (2016). "Effect of electrically heated humidifier on intraoperative core body temperature decrease in elderly patients: a prospective observational study". Anesth Pain Med.
26. (September–October 2006). "Prevention of perioperative hypothermia in plastic surgery.". Aesthet Surg J.
27. (December 2017). "The impact of operative time and hypothermia in acute burn surgery.". Burns.
28. (April 1999). "Maintaining intraoperative normothermia: A meta-analysis of outcomes with costs". AANA Journal.
29. (May 9, 1996). "Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group.". N Engl J Med.
30. (June 8, 2017). "Intraoperative hypothermia and its clinical outcomes in patients undergoing general anesthesia: National study in China.". PLOS ONE.
31. (July 2009). "A comparative evaluation of humidifier with heated wire breathing circuit under general anesthesia.". Korean J Anesthesiol.
32. (January–February 2013). "Effect of active airway warming on body core temperature during adult liver transplantation". Transplant. Proc..
33. (2008). "Heat and Temperature.". Continuing Education in Anaesthesia, Critical Care & Pain.