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Effect of Heating and Humidifying Gas on Patients Undergoing Awake Laparoscopy
May 2001, Vol. 8, No. 2
The Journal of the American Association of Gynecologic Laparoscopists
Effect of Heating and Humidifying Gas on Patients Undergoing Awake Laparoscopy Larry Demco, M.D.
Abstract Study Objective. To determine the effect of heating and humidifying CO2 on the tolerance of awake laparoscopy and frequency of shoulder pain and patient recovery. Design. Randomized, controlled study (Canadian Task Force classification I). Setting. University-affiliated hospital. Patients. Forty consecutive women. Intervention. Awake laparoscopy with and without heating and humidifying CO2. Measurements and Main Results. Heating and humidifying CO2 decreased the frequency of shoulder pain and increased tolerance of the procedure. Thirty percent of patients required no intravenous sedation and did not experience shoulder pain when 3 L of gas or 15 mm Hg pressure was achieved. When shoulder pain did occur with heated and humidified gas, it was brief. Conclusion. Heating and humidifying CO2 increases tolerance of awake laparoscopy and decreases the frequency and duration of shoulder pain. (J Am Assoc Gynecol Laparosc 8(2):247–251, 2001)
bonic acid, which in turn, was thought to be an irritant and stimulated the diaphragmatic nerve, resulting in pain. More recently, researchers began looking at the change of temperature as gas expands from the compressed cylinder to the abdominal cavity. A CO2 temperature of 21° C was recorded when gas exits the Veress needle versus 37° C in the peritoneal cavity.3 This was supported clinically by determining that core body temperature drops 1.64° C during prolonged laparoscopic procedures.4 A third theory as to the cause of shoulder pain focused on the drying effect of CO2 on peritoneal cells. Gas escaping from the Veress needle is of very low humidity, 0.0002%; this results in mesothelial integrity to be lost temporarily and basal lamina to be bare. This phenomenon may lead to cellular death, resulting in chemical irritation.5
At laparoscopy it is necessary to create a space within the peritoneal cavity in order to view abdominal organs. Early surgeons had no resources other than room air to develop this space. Concern over risks1,2 such as air embolism and combustion during electrocoagulation led to the search for a different distention medium. Nitrous oxide, helium, and CO2 were tested, and over the years CO2 became the medium of choice. It is quickly absorbed, does not support combustion, and reduces the risk of air embolism. Its main drawback was the 80% frequency of shoulder pain associated with its use. This was viewed as an acceptable trade-off, however, when comparing benefits of CO2 over those of other gasses. The cause of shoulder pain is largely unexplained, but a widely accepted theory presumed that CO2 reacts with water present in peritoneal fluid and forms car-
From the Department of Obstetrics and Gynecology, University of Calgary, Calgary, Alberta, Canada. Address reprint requests to Larry Demco, M.D., 271 A-1600 90 Avenue SW, Calgary, Alberta T2V 5V8, Canada; fax 403 253 0709. Presented at the 29th annual meeting of the American Association of Gynecologic Laparoscopists, Orlando, Florida, November 15–19, 2000. Second place, Golden Minisite Award. Accepted for publication January 8, 2001.
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Heating and Humidifying Gas During Laparoscopy Demco
was taped so the surgeon could not see condensation there. A 27-gauge needle was used to infiltrate 1% lidocaine at subumbilical and suprapubic access ports. A small skin incision was made. A 25-gauge spinal needle was used to perform a field block in abdominal muscles and fascia in the intended course of the cannula. The 4-mm trocar-cannula was placed through skin and fat until resistance of muscles was encountered and the trocar-cannula was not advanced further. The patient was asked to extend her abdomen so that muscles and fascia moved over the stationary cannula. The 4-mm scope was passed through the port to confirm peritoneal entry, and a maximum 700 ml of CO2 was infused at a rate of 1 L/minute. This low volume caused no rise in intraabdominal pressure. With the patient in 15-degree Trendelenburg position, the 3- or 5-mm access port was placed using similar technique. Once awake laparoscopy was completed, the insufflator was turned back on at a rate of 1 L/minute and the operating room table was placed back to zero degrees. The patient was asked to report when she first experienced shoulder pain or difficulty breathing. The volume of gas was then recorded. No further gas was instilled if intraabdominal pressure of 15 mm Hg was achieved. The total volume was recorded, as well as length of recovery room stay, amount of analgesic required, and length of time necessary for shoulder pain to resolve.
These theories set the basis for clinical trials. By heating and humidifying CO2 before instilling it into the peritoneal cavity, core body temperature was maintained during prolonged laparoscopic procedures, and postoperative pain and length of hospitalization decreased.4 Postoperative pain also was reduced on a visual analog scale with heated and humidified gas over raw gas.6 However, shoulder pain as a result of CO2 limited the amount of gas used to less than 700 ml. Volumes over that amount resulted in increased analgesic requirements to deal with the higher frequency of the pain, which could shorten or preempt surgery. With development of smaller instruments, awake laparoscopy under intravenous conscious sedation,7 patient-assisted laparoscopy,8 and pain mapping9 resulted in more laparoscopies being performed without general anesthesia. Awake laparoscopy is a method of evaluating effects of rate of gas flow, optimum volumes of gas instilled, and effects of heating and humidifying gas on frequency of shoulder pain. The objective of this study was to determine the effects of heating and humidifying CO2 on tolerance of awake laparoscopy; frequency of shoulder pain, and patient recovery. Materials and Methods This double-blind, randomized study enrolled 40 consecutive women (20 patients receiving active treatment, 20 controls) to determine tolerance to increasing volumes of CO2 during awake laparoscopy. Patients were selected on the basis of having had a previous laparoscopy after which they experienced shoulder pain.
Results Marked differences were seen between controls and patients. The frequency of shoulder pain when 700 ml of gas was infused was 30% in controls and 10% in patients in whom heated, humidified gas was used. What was more important was the fact that the pain seemed transitory in patients, only 10% of whom had general anesthesia to complete diagnostic laparoscopy. Once women in the control group experienced shoulder pain, only 50% were able to proceed with awake laparoscopy and the remaining 50% required general anesthesia (Figure 1). Although it is rare to undergo awake laparoscopy without intravenous sedation, 30% of patients in whom the Insuflow device was used did not require an analgesic other than local injection of lidocaine at incision sites. Since patients without shoulder pain were more comfortable than those with it, operating time was increased with heated, humidified gas (Figure 2).
Operative Procedure The Insuflow device (Lexion Medical, St. Paul, MN), which heats and humidifies CO2, was connected from the insufflator to the patient; it is a separate component that is not a part of the insufflator. A wire from the device heats gas leaving the insufflator as it travels down the tubing to the cannula valve. A reservoir 5 cm from the distal connector holds 8 ml of sterile water, which is used to humidify gas to the same humidity as air in the lungs. The temperature of gas at the cannula valve is body temperature (38.5° C). The circulating nurse opened a sealed envelope directing her to have the unit turned on or off during the procedure. To blind the surgeon further, the light on the unit could not be seen, and the plastic tubing
248
May 2001, Vol. 8, No. 2
The Journal of the American Association of Gynecologic Laparoscopists
FIGURE 1. Intraoperative intravenous fentanyl requirements.
FIGURE 2. Operating times.
(Figure 4). Heating and humidifying gas reduced the time for shoulder pain to resolve in patients who experienced pain (Figure 5).
Figure 3 shows differences in amount of gas instilled before patients experienced shoulder pain. Whereas 65% of controls could not tolerate more than 1200 ml CO2, 35% in the test group tolerated pressure of 15 mm Hg or volumes greater than 2700 ml of heated, humidified gas. Seventy percent of patients were discharged within 90 minutes of leaving the operating room, compared with 50% of controls
Discussion Shoulder pain is a main reason for administering general anesthesia for laparoscopy and is the principal
249
Heating and Humidifying Gas During Laparoscopy Demco
FIGURE 3. Total gas instilled (ml).
FIGURE 4. Recovery times (minutes from leaving the operating room to discharge).
250
May 2001, Vol. 8, No. 2
The Journal of the American Association of Gynecologic Laparoscopists
FIGURE 5. Recovery of shoulder pain (hrs).
side effect of the procedure. Although it is hard to achieve statistical significance with such a small sample, heating and humidifying CO2 before infusing it into the peritoneal cavity reduces the frequency of shoulder pain, increase tolerance for awake laparoscopy, and shortens recovery time and duration of shoulder pain should it occur. Heating and humidifying CO2 did not completely eliminate this pain. It may be necessary to determine the gas flow range (should it be 100 ml/min), or change the fluid from sterile water to another medium. The fact that patients tolerated awake laparoscopy may reduce the need for general anesthesia for the procedure. Furthermore, improved recovery in both degree of pain and shorter recovery room times may reduce the cost of performing laparoscopy.
4. Ott D, Reich H, Love B, et al: Reduction of laparoscopicinduced hypothermia, postoperative pain and recovery room length of stay by pre-conditioning gas with the Insuflow device: A prospective randomized controlled multi-center study. J Laparoendosc Surg 2:321–329, 1998 5. Volz J, Koster S, Paweletz N: Characteristic alterations of peritoneum after carbon dioxide pneumoperitoneum. Surg Endosc 13:611–614, 1999 6. Korell M, Schmaus F, Strowitzki T, et al: Pain intensity following laparoscopy. Surg Laparosc Endosc 6(5):375–379, 1996 7. Palter S, Olive D: Office microlaparoscopy under local anesthetic for chronic pelvic pain. J Am Assoc Gynecol Laparosc 3:359–364, 1996
References 8. Demco L: Mapping of pelvic pain under local anesthesia using patient assisted .laparoscopy. In Textbook of Laparoscopy. Edited by J Hulka, H Reich. Philadelphia, WB Saunders, 1998, pp 391–397
1. Gomel V, Taylor P, Yuzpe A, et al, eds: Laparoscopy and Hysteroscopy in Gynecologic Practice. Chicago, Year Book, 1986 2. Ott D: Contamination via gynecologic endoscopy insufflation. J Gynecol Surg 5:205–208, 1989
9. Demco L: Mapping the source and character of pain due to endometriosis by patient-assisted laparoscopy. J Am Assoc Gynecol Laparosc 5(3):241–245, 1998
3. Ott D: Laparoscopic hypothermia. J Laparosc Surg 1(3):127–131, 1991
251
The Journal of the American Association of Gynecologic Laparoscopists
Effect of Heating and Humidifying Gas on Patients Undergoing Awake Laparoscopy Larry Demco, M.D.
Abstract Study Objective. To determine the effect of heating and humidifying CO2 on the tolerance of awake laparoscopy and frequency of shoulder pain and patient recovery. Design. Randomized, controlled study (Canadian Task Force classification I). Setting. University-affiliated hospital. Patients. Forty consecutive women. Intervention. Awake laparoscopy with and without heating and humidifying CO2. Measurements and Main Results. Heating and humidifying CO2 decreased the frequency of shoulder pain and increased tolerance of the procedure. Thirty percent of patients required no intravenous sedation and did not experience shoulder pain when 3 L of gas or 15 mm Hg pressure was achieved. When shoulder pain did occur with heated and humidified gas, it was brief. Conclusion. Heating and humidifying CO2 increases tolerance of awake laparoscopy and decreases the frequency and duration of shoulder pain. (J Am Assoc Gynecol Laparosc 8(2):247–251, 2001)
bonic acid, which in turn, was thought to be an irritant and stimulated the diaphragmatic nerve, resulting in pain. More recently, researchers began looking at the change of temperature as gas expands from the compressed cylinder to the abdominal cavity. A CO2 temperature of 21° C was recorded when gas exits the Veress needle versus 37° C in the peritoneal cavity.3 This was supported clinically by determining that core body temperature drops 1.64° C during prolonged laparoscopic procedures.4 A third theory as to the cause of shoulder pain focused on the drying effect of CO2 on peritoneal cells. Gas escaping from the Veress needle is of very low humidity, 0.0002%; this results in mesothelial integrity to be lost temporarily and basal lamina to be bare. This phenomenon may lead to cellular death, resulting in chemical irritation.5
At laparoscopy it is necessary to create a space within the peritoneal cavity in order to view abdominal organs. Early surgeons had no resources other than room air to develop this space. Concern over risks1,2 such as air embolism and combustion during electrocoagulation led to the search for a different distention medium. Nitrous oxide, helium, and CO2 were tested, and over the years CO2 became the medium of choice. It is quickly absorbed, does not support combustion, and reduces the risk of air embolism. Its main drawback was the 80% frequency of shoulder pain associated with its use. This was viewed as an acceptable trade-off, however, when comparing benefits of CO2 over those of other gasses. The cause of shoulder pain is largely unexplained, but a widely accepted theory presumed that CO2 reacts with water present in peritoneal fluid and forms car-
From the Department of Obstetrics and Gynecology, University of Calgary, Calgary, Alberta, Canada. Address reprint requests to Larry Demco, M.D., 271 A-1600 90 Avenue SW, Calgary, Alberta T2V 5V8, Canada; fax 403 253 0709. Presented at the 29th annual meeting of the American Association of Gynecologic Laparoscopists, Orlando, Florida, November 15–19, 2000. Second place, Golden Minisite Award. Accepted for publication January 8, 2001.
247
Heating and Humidifying Gas During Laparoscopy Demco
was taped so the surgeon could not see condensation there. A 27-gauge needle was used to infiltrate 1% lidocaine at subumbilical and suprapubic access ports. A small skin incision was made. A 25-gauge spinal needle was used to perform a field block in abdominal muscles and fascia in the intended course of the cannula. The 4-mm trocar-cannula was placed through skin and fat until resistance of muscles was encountered and the trocar-cannula was not advanced further. The patient was asked to extend her abdomen so that muscles and fascia moved over the stationary cannula. The 4-mm scope was passed through the port to confirm peritoneal entry, and a maximum 700 ml of CO2 was infused at a rate of 1 L/minute. This low volume caused no rise in intraabdominal pressure. With the patient in 15-degree Trendelenburg position, the 3- or 5-mm access port was placed using similar technique. Once awake laparoscopy was completed, the insufflator was turned back on at a rate of 1 L/minute and the operating room table was placed back to zero degrees. The patient was asked to report when she first experienced shoulder pain or difficulty breathing. The volume of gas was then recorded. No further gas was instilled if intraabdominal pressure of 15 mm Hg was achieved. The total volume was recorded, as well as length of recovery room stay, amount of analgesic required, and length of time necessary for shoulder pain to resolve.
These theories set the basis for clinical trials. By heating and humidifying CO2 before instilling it into the peritoneal cavity, core body temperature was maintained during prolonged laparoscopic procedures, and postoperative pain and length of hospitalization decreased.4 Postoperative pain also was reduced on a visual analog scale with heated and humidified gas over raw gas.6 However, shoulder pain as a result of CO2 limited the amount of gas used to less than 700 ml. Volumes over that amount resulted in increased analgesic requirements to deal with the higher frequency of the pain, which could shorten or preempt surgery. With development of smaller instruments, awake laparoscopy under intravenous conscious sedation,7 patient-assisted laparoscopy,8 and pain mapping9 resulted in more laparoscopies being performed without general anesthesia. Awake laparoscopy is a method of evaluating effects of rate of gas flow, optimum volumes of gas instilled, and effects of heating and humidifying gas on frequency of shoulder pain. The objective of this study was to determine the effects of heating and humidifying CO2 on tolerance of awake laparoscopy; frequency of shoulder pain, and patient recovery. Materials and Methods This double-blind, randomized study enrolled 40 consecutive women (20 patients receiving active treatment, 20 controls) to determine tolerance to increasing volumes of CO2 during awake laparoscopy. Patients were selected on the basis of having had a previous laparoscopy after which they experienced shoulder pain.
Results Marked differences were seen between controls and patients. The frequency of shoulder pain when 700 ml of gas was infused was 30% in controls and 10% in patients in whom heated, humidified gas was used. What was more important was the fact that the pain seemed transitory in patients, only 10% of whom had general anesthesia to complete diagnostic laparoscopy. Once women in the control group experienced shoulder pain, only 50% were able to proceed with awake laparoscopy and the remaining 50% required general anesthesia (Figure 1). Although it is rare to undergo awake laparoscopy without intravenous sedation, 30% of patients in whom the Insuflow device was used did not require an analgesic other than local injection of lidocaine at incision sites. Since patients without shoulder pain were more comfortable than those with it, operating time was increased with heated, humidified gas (Figure 2).
Operative Procedure The Insuflow device (Lexion Medical, St. Paul, MN), which heats and humidifies CO2, was connected from the insufflator to the patient; it is a separate component that is not a part of the insufflator. A wire from the device heats gas leaving the insufflator as it travels down the tubing to the cannula valve. A reservoir 5 cm from the distal connector holds 8 ml of sterile water, which is used to humidify gas to the same humidity as air in the lungs. The temperature of gas at the cannula valve is body temperature (38.5° C). The circulating nurse opened a sealed envelope directing her to have the unit turned on or off during the procedure. To blind the surgeon further, the light on the unit could not be seen, and the plastic tubing
248
May 2001, Vol. 8, No. 2
The Journal of the American Association of Gynecologic Laparoscopists
FIGURE 1. Intraoperative intravenous fentanyl requirements.
FIGURE 2. Operating times.
(Figure 4). Heating and humidifying gas reduced the time for shoulder pain to resolve in patients who experienced pain (Figure 5).
Figure 3 shows differences in amount of gas instilled before patients experienced shoulder pain. Whereas 65% of controls could not tolerate more than 1200 ml CO2, 35% in the test group tolerated pressure of 15 mm Hg or volumes greater than 2700 ml of heated, humidified gas. Seventy percent of patients were discharged within 90 minutes of leaving the operating room, compared with 50% of controls
Discussion Shoulder pain is a main reason for administering general anesthesia for laparoscopy and is the principal
249
Heating and Humidifying Gas During Laparoscopy Demco
FIGURE 3. Total gas instilled (ml).
FIGURE 4. Recovery times (minutes from leaving the operating room to discharge).
250
May 2001, Vol. 8, No. 2
The Journal of the American Association of Gynecologic Laparoscopists
FIGURE 5. Recovery of shoulder pain (hrs).
side effect of the procedure. Although it is hard to achieve statistical significance with such a small sample, heating and humidifying CO2 before infusing it into the peritoneal cavity reduces the frequency of shoulder pain, increase tolerance for awake laparoscopy, and shortens recovery time and duration of shoulder pain should it occur. Heating and humidifying CO2 did not completely eliminate this pain. It may be necessary to determine the gas flow range (should it be 100 ml/min), or change the fluid from sterile water to another medium. The fact that patients tolerated awake laparoscopy may reduce the need for general anesthesia for the procedure. Furthermore, improved recovery in both degree of pain and shorter recovery room times may reduce the cost of performing laparoscopy.
4. Ott D, Reich H, Love B, et al: Reduction of laparoscopicinduced hypothermia, postoperative pain and recovery room length of stay by pre-conditioning gas with the Insuflow device: A prospective randomized controlled multi-center study. J Laparoendosc Surg 2:321–329, 1998 5. Volz J, Koster S, Paweletz N: Characteristic alterations of peritoneum after carbon dioxide pneumoperitoneum. Surg Endosc 13:611–614, 1999 6. Korell M, Schmaus F, Strowitzki T, et al: Pain intensity following laparoscopy. Surg Laparosc Endosc 6(5):375–379, 1996 7. Palter S, Olive D: Office microlaparoscopy under local anesthetic for chronic pelvic pain. J Am Assoc Gynecol Laparosc 3:359–364, 1996
References 8. Demco L: Mapping of pelvic pain under local anesthesia using patient assisted .laparoscopy. In Textbook of Laparoscopy. Edited by J Hulka, H Reich. Philadelphia, WB Saunders, 1998, pp 391–397
1. Gomel V, Taylor P, Yuzpe A, et al, eds: Laparoscopy and Hysteroscopy in Gynecologic Practice. Chicago, Year Book, 1986 2. Ott D: Contamination via gynecologic endoscopy insufflation. J Gynecol Surg 5:205–208, 1989
9. Demco L: Mapping the source and character of pain due to endometriosis by patient-assisted laparoscopy. J Am Assoc Gynecol Laparosc 5(3):241–245, 1998
3. Ott D: Laparoscopic hypothermia. J Laparosc Surg 1(3):127–131, 1991
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