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Mechanical insufflation-exsufflation: pressure, volume, and flow relationships and the adequacy of the manufacturer's guidelines.

OBJECTIVE: Pulmonary complications of neuromuscular disease can be averted by increasing peak cough flows with the use of a forced exsufflation device. The purpose of this study was to examine the pressure, volume, and flow relationships for a range of settings generated by this device, and compare them with clinically efficacious values and the manufacturer's guidelines. METHODS: The In-exsufflator was connected to a standard lung model. The resulting forced deflation volumes, flows, and pressures were averaged over 10 cycles at each setting. RESULTS: The set insufflation pressures significantly correlated with the generated insufflation pressures and volumes and the exsufflation volumes and flows. Increasing set insufflation time significantly increased generated insufflation pressures, flows, and volumes and exsufflation volumes. Increasing set exsufflation time did not significantly increase generated exsufflation flows. At set pressures of 40 to -40 cm H2O, insufflation time of 3 sec, and exsufflation time of 2 sec, the exsufflation flow was 4.09 l/sec. A plateau insufflation volume of 3.8 l was reached after 4.9 sec of insufflation. CONCLUSIONS: In-exsufflator performance was very consistent. Its clinical effectiveness can be explained by its generation of exsufflation flows >2.7 l/sec. Increasing insufflation times more than exsufflation times is more important for optimal function. Current manufacturer use guidelines may not yield optimal exsufflation flows.

Cough↗

Helium versus oxygen for tracheal gas insufflation during mechanical ventilation.

OBJECTIVE: To evaluate and compare the effect of tracheal gas insufflation using two gases with different physical properties, helium and oxygen, as an adjunct to conventional mechanical ventilation in patients with respiratory failure. DESIGN: Prospective, intervention study. SETTING: General intensive care unit in a tertiary university medical center. PATIENTS: Seven sedated and paralyzed patients with respiratory failure of various etiologies. All patients were ventilated in the volume-control mode (tidal volume 5 to 7 mL/kg). Inclusion criteria were PaCO2 of > or =50 torr (> or =6.7 kPa), together with peak inspiratory pressure of > or =35 cm H2O and respiratory rate of > or =14 breaths/min. INTERVENTIONS: All patients were intubated with an endotracheal tube that had an additional lumen opening at its distal end, through which tracheal gas insufflation was administered. The tracheal gas insufflation was applied continuously throughout the respiratory cycle at three flow rates (2, 4, and 6 L/min) with two gases, oxygen and helium, while the ventilatory settings were maintained constant. MEASUREMENTS AND MAIN RESULTS: In addition to airway pressures and arterial blood gases, the relative efficacy of tracheal gas insufflation with each gas was estimated using a "coefficient of efficiency" (which we defined as the change in PaCO2/peak inspiratory pressure) compared with baseline measurements. Tracheal gas insufflation with both gases decreased PaCO2 significantly (p < .05) at all flow rates. This effect was accompanied by an increase in airway pressure with both gases (oxygen and helium). However, at flow rates of 6 L/min, tracheal gas insufflation with helium resulted in lower peak inspiratory pressure than with oxygen. Tracheal gas insufflation with helium was more effective (as estimated by the coefficient of efficiency) than with oxygen at all flow rates (p < .05). CONCLUSION: In volume-controlled, mechanically ventilated patients with respiratory failure, tracheal gas insufflation with helium might be suggested as an alternative to oxygen.

Acute Disease↗

Tumour cell movement during heating and humidification of insufflating CO2: an in vitro model.

BACKGROUND: Intra-operative hypothermia and port-site recurrence have been associated with laparoscopic surgery. Heating and humidification of insufflating CO2 may protect against laparoscopy-associated hypothermia. However, the effect of heated, humidified CO2 upon tumour cell movement is unknown. METHODS: Twenty-four in vitro studies that used 4-L plastic bottles were performed. Thirteen million human colorectal cancer cells were placed in each bottle. Twelve studies used dry room temperature CO2 for insufflation: the remaining 12 used heated, humidified CO2 as the insufflating gas. Both groups were subdivided into bottles with leaks around the trocars and with airtight sealing around the trocars. Two trocars and a laparoscopic grasper were used. The exiting insufflating gas was filtered and examined for the presence of cells. Laparoscopic instruments agitated the contents of the bottles. The instruments and trocars were washed. These washings were examined for the presence of cells. RESULTS: Heated, humidified CO2 insufflation was able to maintain a warmer and more humid environment within the bottles when compared with dry room-temperature CO2. No cells were detected on the gas filters. Tumour cells were found on 12 out of 12 instruments and 11 out of 12 trocars with dry CO2 insufflation. Tumour cells were found on 8 out of 12 instruments and 7 out of 12 trocars with heated humidified CO2 insufflation. The only statistically significant difference in tumour cell spread to trocars was found between heating and humidification when no leak was present, and heating and humidification with leak present, and dry insufflation with no leak present (P = 0.015, Fisher's two-tailed exact test). CONCLUSIONS: Heating and humidifying CO2 during in vitro laparoscopy does not increase the aerosolization of tumour cells when compared with dry CO2. However, the use of heated and humidified gas with airtight seals around the trocars in vitro may lessen cell deposition on trocars.

Carbon Dioxide↗

Effect of manually assisted cough and mechanical insufflation on cough flow of normal subjects, patients with chronic obstructive pulmonary disease (COPD), and patients with respiratory muscle weakness.

BACKGROUND: It has been suggested that cough effectiveness can be improved by assisted techniques. The effects of manually assisted cough and mechanical insufflation on cough flow physiology are reported in this study. METHODS: The physiological actions and patient self-assessment of manually assisted cough and mechanical insufflation were investigated in 29 subjects (nine normal subjects, eight patients with chronic obstructive pulmonary disease (COPD), four subjects with respiratory muscle weakness (RMW) with scoliosis, and eight subjects with RMW without scoliosis). RESULTS: The peak cough expiratory flow rate and cough expiratory volume were not improved by manually assisted cough and mechanical insufflation alone or in combination in normal subjects. The median increase in peak cough expiratory flow in subjects with RMW without scoliosis with manually assisted cough alone or in combination with mechanical insufflation of 84 l/min (95% confidence interval (CI) 19 to 122) and 144 l/min (95% CI 14 to 195), respectively, reflects improvement in the expulsive phase of coughing by these techniques. Manually assisted cough and mechanical insufflation in combination raised peak expiratory flow rate more than either technique alone in this group. The abnormal chest shape in scoliotic subjects and the fixed inspiratory pressure used made effective manually assisted cough and mechanical insufflation difficult in this group and no improvements were found. In patients with COPD manually assisted cough alone and in combination with mechanical insufflation decreased peak expiratory flow rate by 144 l/min (95% CI 25 to 259) and 135 l/min (95% CI 30 to 312), respectively. CONCLUSIONS: Manually assisted cough and mechanical insufflation should be considered to assist expectoration of secretions in patients with RMW without scoliosis but not in those with scoliosis.

Adolescent↗

Continuous endobronchial insufflation during internal mammary artery harvest.

Endobronchial insufflation of oxygen offers possible advantages over conventional ventilation modes in some clinical situations in which nonmovement of the chest may be desirable; however, endobronchial insufflation of oxygen has yet to be used during thoracic surgery in humans. Furthermore, the physiologic mechanisms underlying gas exchange during endobronchial insufflation of oxygen are unclear. This study assessed endobronchial insufflation of oxygen at 45 L/min in 11 patients with an open chest during internal mammary artery harvest. Cardiorespiratory function was measured at baseline during conventional mechanical ventilation and at 5-min intervals during the study period of 20-30 min. In all patients, clinically acceptable gas exchange was achieved, although PaCO2 increased from 32 +/- 3.2 to 44 +/- 7.5 mm Hg (mean +/- SD) at 5 min, but thereafter was unchanged (P greater than 0.1). Cardiac output, vascular pressures, and heart rate were unchanged, although pHa decreased. Surgical access for internal mammary artery harvesting was improved. No mucosal damage or complications occurred. During endobronchial insufflation of oxygen, efficacy of gas exchange and body weight were not correlated, but both subject height and age were correlated with high PaO2 and low PaCO2. We conclude that (a) endobronchial insufflation of oxygen can be used in patients with an open chest; (b) the efficacy of endobronchial insufflation of oxygen is probably improved by increased lung size and by collateral ventilation; and (c) cardiogenic gas mixing contributes little to gas exchange during endobronchial insufflation of oxygen.

Aged↗

Time course of differences in lymphocyte proliferation rates after laparotomy vs CO(2) insufflation.

BACKGROUND: Our laboratory has previously demonstrated that cell-mediated immune function is significantly more suppressed after both laparotomy and laparoscopic-assisted bowel resection than after peritoneal insufflation or open bowel resection, as assessed by delayed-type hypersensitivity (DTH) response. The purpose of this study was to further evaluate cell-mediated immunity by examining lymphocyte proliferation rates after laparotomy vs CO(2) insufflation. METHODS: Female Balb/C mice (n = 75) were randomly divided into the following three groups: (a) anesthesia control (A/C), (b) CO(2) insufflation (INS), and (c) sham laparotomy (OPEN). The A/C group mice underwent no procedure. The INS group underwent insufflation with CO(2) gas at 4-6 mmHg for 20 min. The OPEN group underwent a midline incision from xiphoid to pubic symphysis, which was clipped closed after 20 min. Splenocytes were obtained via splenic harvest and lymphocyte isolation on postoperative days (POD) 1, 2, 3, 4, and 8. Lymphocyte proliferation was determined by a nonradioactive colorimetric MTS/PMS assay 72 h after concanavalin A stimulation. RESULTS: The laparotomy group's lymphocyte proliferation rates were significantly lower than both the control and the insufflation groups on POD 2, POD 3, and POD 4. On POD 1 and POD 8, there were no significant differences in lymphocyte proliferation among the three groups. No differences were found between the control and insufflation groups at any point. CONCLUSIONS: After stimulation, lymphocytes proliferate at a lower rate after laparotomy than after CO(2) insufflation. Significant differences in lymphocyte proliferation rates between groups persist at least through POD 4. By POD 8, the mean lymphocyte proliferation rate in the laparotomy group was back to the baseline level. Our results suggest greater immunosuppression after sham laparotomy than after CO(2) insufflation.

Animals↗

Continuous low-flow supracarinal and subcarinal oxygen insufflation in addition to intermittent positive-pressure ventilation does not improve gas exchange.

Recent studies in animals have demonstrated that continuous insufflation of oxygen near the tracheal carina results in ventilation and carbon dioxide removal that is proportional to the flow rate. The purpose of this study was to determine whether the addition of supracarinal and subcarinal low-flow oxygen insufflation to conventional intermittent positive-pressure ventilation (IPPV) of critically ill and anesthetized patients results in increased ventilation and improved oxygenation. In eight studies a supracarinal catheter (3.7 mm OD) was placed 1 to 2 cm above the carina, and in another eight studies two subcarinal catheters (1.7 mm OD) were placed 2 cm below the tracheal carina under direct vision with a fiberoptic bronchoscope. Both supracarinal and subcarinal catheters were passed within the lumen of an 8 mm ID endotracheal tube. In both groups, conventional IPPV consisted of a tidal volume of 10-12 mL/kg, respiratory rate of 8 to 10 breaths/min, 0 cm H2O positive end-expiratory pressure (PEEP), and F1O2 of 1.0. In both groups, continuous oxygen insufflation flow rates were 0.05, 0.10, and 0.20 L/ kg/min. It was found that compared with control conditions (no insufflation), oxygen insufflation at all flow rates in both supracarinal and subcarinal insufflation groups did not cause any significant change in either oxygenation or ventilation. There was a significant increase in proximal peak airway pressure with each incremental increase in continuous oxygen flow rate. Conversely, there was a significant decrease in mean arterial pressure and cardiac output with each incremental increase in continuous oxygen flow rate. It is concluded that use of continuous low-flow insufflation of oxygen with simple administration systems (catheters within the lumen of endotracheal tube) in addition to conventional IPPV is contraindicated at the present time. Further studies using different insufflation systems may prove to be worthwhile.

Adult↗

Intra-airway CO2 distribution during airway insufflation in ventilatory failure.

Low-flow intratracheal gas insufflation is known to be an effective means of providing partial ventilatory support in respiratory failure. We studied the effects of catheter position on intraluminal CO2 concentration profiles and gas transport resistance during intra-airway insufflation at 0.15 l.kg-1.min-1 in six anesthetized paralyzed mechanically hypoventilated dogs. The two positions of the distal tip of the insufflation catheter were 0.5 cm proximal to and 4.0 cm distal to the carina. Local airway CO2 concentrations were measured via a sampling catheter passed through the tracheobronchial tree. Resistance to gas transport was calculated from the measured data. Arterial PO2 and arterial PCO2 remained constant with carinal and bronchial insufflation. Distal positioning of the insufflation tip resulted in a redistribution of ventilation between the lungs, with the ipsilateral lung being relatively hyperventilated and the contralateral lung being relatively hypoventilated. Intraluminal CO2 concentrations were markedly reduced in the ipsilateral lung compared with the profile in the contralateral lung during fresh gas delivery into the main-stem bronchus. The region of peak transport resistance was found to be in the second-generation airways during carinal insufflation and in the fourth-generation airways with intrabronchial insufflation. We conclude that gas exchange during low-flow insufflation occurs by the same mechanisms responsible for CO2 elimination in constant-flow ventilation. Overall gas exchange is not affected by position of the jet catheter.

Airway Resistance↗

Comparison between CO2 insufflation and abdominal wall lift in laparoscopic cholecystectomy. A prospective multiinstitutional study in Japan.

BACKGROUND: Abdominal wall lift (AWL) was developed mainly in Japan to avoid insufflation-related complications and to improve cost performance. AWL, however, has been criticized for its poor visibility in obese patients, the complexity of preparing the lifting instruments, and increased inflammatory reactions. As experience with AWL has increased, proponents of the procedure have come to believe that AWL is simple enough to qualify as a standard method of laparoscopic surgery even in obese patients. Postoperatively, issues such as pain, changes in body temperature, and time before returning to work do not appear to be much different from those after CO2 insufflation. METHODS: Twenty-three institutions participated in a prospective study to compare the effects of insufflation and AWL on surgical performance and postoperative course of laparoscopic surgery. Biochemical markers were also investigated including inflammatory responses. The patients were allocated to the participants to prevent experience-biases. A total of 144 patients were reviewed. RESULTS: Background factors such as male-female ratio, age and body-mass index were similar in each group. The incidence of conversion-to-open was not significantly different between insufflation and AWL. Preparation time and operating time were not significantly different, either. Serum CPK showed a significantly higher value one day after peritoneal lift than after subcutaneous lift. CPK level after insufflation was between that of peritoneal lift and after subcutaneous lift. Differences in changes of plasma interleukin 6 and other surgical stress markers were not observed. CONCLUSIONS: This prospective study, although not randomized, suggests that, except for invasiveness to the muscular layers of the abdominal wall, there may be no substantial difference between AWL and insufflation or among subcutaneous lift, peritoneal lift or insufflation in terms of morbidity, mortality, preparation time, operating time, inflammatory reactions, and postoperative clinical course.

Abdominal Muscles↗

Effects of expiratory tracheal gas insufflation in patients with severe head trauma and acute lung injury.

OBJECTIVE: This study analyzed the effect of phasic tracheal gas insufflation at mid- to end-expiration in patients with severe head trauma and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). DESIGN AND SETTING: A prospective interventional study in a 16-bed intensive care unit. PATIENTS: Seven patients with severe head trauma (Glasgow Coma Scale <9) and ALI/ARDS. INTERVENTIONS: Patients were ventilated in assist/control mode with a ventilatory strategy providing adequate oxygenation (PaO(2) >70 mmHg) and normocapnia (PaCO(2) between 35-40 mmHg). Mid to end expiratory tracheal gas insufflation at 8 l/min flow rate was delivered for 90 min while normocapnia was maintained by simultaneous reductions in tidal volume. We measured (hemodynamics, oxygenation, lung mechanics, and cerebral parameters) in basal situation and during and after tracheal insufflation. MEASUREMENTS AND RESULTS: Tracheal gas insufflation allowed a significant decrease in tidal volume from 9.1 to 7.2 ml/kg, with associated reduction in driving pressure (plateau pressure minus positive end-expiratory pressure, PEEP) from 18.1 to 13.2 cm H(2)O. Total PEEP increased from 9.3 to 12.7 cm H(2)O due to the generation of lung hyperinflation. Oxygenation improved slightly during tracheal gas insufflation, and this improvement remained after stopping tracheal insufflation. No changes in hemodynamic or cerebral parameters were observed during the study. CONCLUSIONS: In patients with severe head trauma and ALI receiving mechanical ventilation, expiratory tracheal gas insufflation allowed the targeted arterial PCO(2) level to be maintained together with a substantial reduction in tidal volume.

Adult↗

Reduction of abdominal wall blood flow by clamping or carbon dioxide insufflation increases tumor growth in the abdominal wall: an experimental study in rats.

BACKGROUND: We have previously demonstrated that there is a reduction of blood flow in the abdominal wall in rats insufflated with air concomitant with an increase in tumor growth. The present study was designed to examine whether a reduction of blood flow achieved by clamping or insufflation with carbon dioxide (CO(2)) would increase tumor growth in the abdominal wall. METHODS: In the first part of the experiments, laser Doppler blood flow of both rectus muscles was measured in 16 Wistar Fu rats. The left rectus muscle was clamped to reduce blood flow, and 5 x 10(4) adenocarcinoma cells were injected into both rectus muscles. Clamping was maintained for 45 min. In the second part, 22 rats had 5 x 10(4) adenocarcinoma cells injected into the rectus muscle and blood flow was measured. The experimental group (n = 11) was insufflated with CO(2) at 10 mmHg for 45 min; the control group (n = 11) was not insufflated. After 9 days, tumor weight and volume were analyzed. RESULTS: Clamping caused a 69% reduction of blood flow (p < 0.001), whereas no reduction was registered on the nonclamped side. Tumor weight (p = 0.028) and volume (p = 0.030) were increased on the clamped side. The insufflation of CO(2) caused a 71% reduction of blood flow, whereas no reduction was registered in the control group. Tumor weight (p = 0.006) and volume (p = 0.006) were increased in the insufflated group. CONCLUSION: Clamping, as well as CO(2) insufflation, causes a significant reduction of blood flow in the abdominal wall, which seems to increase tumor growth at the same site.

Abdominal Neoplasms↗

CO2 environment influences the growth of cultured human cancer cells dependent on insufflation pressure.

BACKGROUND: Experimental and clinical studies, have suggested that the CO2 pneumoperitoneum influences the development of intraabdominal tumor dissemination and port site metastases. Previous experiments performed both in vitro and in vivo have proved that CO2 insufflation stimulates malignant cell growth. Therefore, we designed a study to investigate the influence of CO2 insufflation administered at different pressures on the growth of cultured human tumor cells. METHODS: Two human tumor cell lines (CX-2 colon adenocarcinoma, DAN-G pancreas adenocarcinoma) were exposed to a CO2 environment maintained at different pressures (0 mmHg, 6 mmHg, 12 mmHg). Tumor growth was determined at different times after exposure to CO2 using fluorescence photometry. Cytotoxity of the CO2 environment different pressures was investigated using flow cytometry. RESULTS: At 1-4 days after exposure to CO2 insufflation, CX-2 and DAN-G tumor cell growth was decreased significantly (p < 0.01). Proliferation of pancreatic adenocarcinoma DAN-G increased significantly from day 5 to day 15 independent of the insufflation pressure (p < 0.01). Proliferation of colon adenocarcinoma CX-2 increased significantly from day 5 to day 15 but was found to be dependent on the insufflation pressure. CX-2 growth increased significantly with higher pressures (p < 0.05). CONCLUSION: CO2 insufflation influences the growth of cultured human tumor cells. After a short period of suppression, the CO2 environment stimulates malignant cell growth. The insufflation pressure may also have additional effects in promoting tumor growth.

Adenocarcinoma↗

A randomized controlled trial assessing the benefit of humidified insufflation gas during laparoscopic surgery.

BACKGROUND: We conducted a randomized controlled trial during laparoscopic cholecystectomy to determine the extent of heat preservation and postoperative pain reduction using humidified carbon dioxide (CO2) gas insufflation instead of standard dry insufflation gas. METHODS: Forty consecutive patients were randomized. Twenty patients received humidified CO2, and 20 control patients received standard CO2 insufflation. A sample of 16 patients from each group was evaluated for postoperative pain levels. RESULTS: No adverse effects from the humidification of insufflated gas were observed. There was no significant difference in core body temperature between the two groups for this brief operation. Pain, as assessed by the Analogue Pain Score (APS) was significantly less for the group with humidified gas insufflation than for the control group at 6 h postoperatively as well as on the 1st, 2nd, and 3rd postoperative day and at follow-up 10 days after the operation. In the humidified group, the mean time to return to normal activities was significantly less-5.9 days, as compared to 10.9 days in the control group. CONCLUSIONS: The use of humidified insufflation gas reduces postoperative pain following laparoscopic cholecystectomy, but except for these relatively brief procedures, the heat-preserving effect of humidified gas insufflation is not significant.

Adult↗

A comparison of the hemodynamic and metabolic effects of extraperitoneal carbon dioxide and nitrous oxide insufflation.

BACKGROUND: The aim of the present study was to compare the hemodynamic and metabolic effects of extraperitoneal carbon dioxide (CO(2)) and nitrous oxide (N(2)O) insufflation. MATERIAL AND METHODS: Fourteen dogs were used in the experiment. All the animals were intubated under general anesthesia. A catheter was placed into the right jugular vein for central venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and heart rate (HR) monitorization. End-tidal CO(2) pressure was measured by a capnometer connected to the endotracheal tube. Another catheter was inserted into the left femoral artery for arterial blood gas analysis and blood pressure monitorization. The preperitoneal dissection was made from a 1.5 cm subumbilical incision by using a preperitoneal dissection balloon. A laparoscope was placed in the preperitoneal space and the gas insufflation was kept at a constant pressure of 12 mm Hg throughout the experiment. All the study parameters were measured at the beginning of the insufflation and at every 15 minutes for 1 hour. RESULTS: Mean artery pressure increased with time in both groups, but the increase was only significant in the CO(2) group. PWP, CVP, PAP, and HR increased slightly in both groups, but there was no significant difference between the groups. The end-tidal CO(2) increased in the CO(2) group but decreased from the baseline in the N(2)O group. A significant acidosis was observed in only the CO(2) group. PaCO(2) significantly increased in the CO(2) group; hence, PaCO(2) slightly decreased in N(2)O group. The difference between the groups was significant. CONCLUSIONS: N(2)O insufflation of the extraperitoneal space in dogs avoided the unwanted metabolic and hemodynamic side effects of CO(2) insufflation. Thus, N(2)O insufflation in the extraperitoneal space is a safer alternative to CO(2) insufflation experimentally, and can be preferred especially in patients with cardiac and pulmonary diseases.

Animals↗

Carbon dioxide insufflation in colonoscopy: safe and effective in sedated patients.

BACKGROUND AND STUDY AIMS: Several studies have shown that insufflation of carbon dioxide (CO2) instead of air during colonoscopy can reduce postprocedural pain. However, CO2 insufflation might also lead to CO2 retention in the human body. It was recently shown that this side effect does not occur in unsedated patients, but that sedation leads to impaired respiration. Sedated patients may therefore be more prone to CO2 retention. This randomized, double-blinded study was designed to investigate whether CO2 insufflation leads to CO2 retention in sedated patients. PATIENTS AND METHODS: A total of 103 consecutive patients undergoing colonoscopy were randomly assigned to the use of either CO2 or air insufflation. End-tidal carbon dioxide (ETCO2), a noninvasive parameter for arterial P CO2, was recorded before the examination, twice during it, and 10 min after it. Midazolam or pethidine, or both, were used for sedation. The patient's pain during the examination and 1, 3, 6, and 24 h afterwards was registered using a questionnaire. RESULTS: CO2 was used in 52 patients and air insufflation in 51. A total of 52 patients (51 %) received sedation. There were no differences in ETCO2 between the CO2 and air group. A slight increase in ETCO2 was observed in sedated patients, while there was no increase in unsedated patients. CO2 insufflation significantly reduced pain after the procedure at all time points. CONCLUSIONS: This study indicates that CO2 insufflation reduces pain and is safe to use in colonoscopy for sedated patients.

Aged↗

Carbon dioxide insufflation reduces discomfort due to flexible sigmoidoscopy in colorectal cancer screening.

BACKGROUND: Flexible sigmoidoscopy is currently recommended as a screening modality for colorectal cancer. However, a substantial number of patients experience discomfort because of the procedure. possibly limiting compliance and thus screening success. During endoscopy, air is commonly used to insufflate the bowel. Carbon dioxide rather than air insufflation has been shown to reduce procedure-related pain and discomfort in colonoscopy. The aim of the present study was to evaluate whether carbon dioxide insufflation reduces discomfort during and after flexible sigmoidoscopy for colorectal cancer screening. METHODS: In a randomized, double-blinded design, 230 consecutive participants in a population-based flexible sigmoidoscopy colorectal cancer screening trial were assigned to have their examination performed with either carbon dioxide or air insufflation. Patients were asked to grade discomfort experienced both during and in the hours after the procedure on a visual analogue scale. RESULTS: Carbon dioxide insufflation significantly reduced the amount of discomfort at 1, 3 and 6 h after the sigmoidoscopy. One hour after the examination. 84% of patients in the CO2 group reported no discomfort, compared to 64% in the air group (P = 0.006). No differences between the groups were observed during the examination. CONCLUSIONS: Carbon dioxide insufflation significantly reduced post-examination discomfort. The use of carbon dioxide rather than air insufflation may contribute to better public acceptance for flexible sigmoidoscopy screening.

Carbon Dioxide↗

Effect of abdominal insufflation on bacterial growth in experimental peritonitis.

BACKGROUND: Perforated appendicitis can be treated laparoscopically, but this approach is associated with a higher rate of intra-abdominal abscess. Pneumoperitoneum impairs the clearance of bacteria from the peritoneal cavity in experimental models of peritonitis. The aim of this study was to investigate the effects of intra-abdominal gas insufflation on bacterial growth in a rat model. MATERIALS AND METHODS: The effects of intraperitoneal insufflation with different gases and a gasless model on bacterial proliferation in a setting of Escherichia coli-induced experimental peritonitis were studied in a rat model. Saline (0.25 mL) was given intraperitoneally to six Wistar male rats as the sham group. Escherichia coli (1.5 x 10(9) cfu/mL per kilogram) was injected intraperitoneally into to 24 rats. Microorganism counts were taken after 8 hours, and rats were divided into three groups: group 1, CO2 insufflation; group 2, N2O insufflation; and group 3, no insufflation. Microorganism counts were repeated 8 hours after the procedure (at 16 hours postinjection). RESULTS: The difference in microorganism counts between 8 and 16 hours were significant in the CO2 and N2O insufflation groups (P < 0.05) but not in the group without pneumoperitoneum. CONCLUSIONS: Abdominal insufflation may promote intra-abdominal bacterial growth or decrease intra-abdominal bacterial clearance.

Animals↗

Is carbon dioxide insufflation safe for laparoscopic surgery? A model to assess the effects of carbon dioxide on transitional-cell carcinoma growth, apoptosis, and necrosis.

PURPOSE: To study the effects of carbon dioxide insufflation pressure and concentration on the adhesion, growth, apoptosis, and necrosis of transitional-cell carcinoma (TCC). MATERIALS AND METHODS: Adhesion and growth of the AY-27 rat TCC cell line was measured after CO2 insufflation in vitro at different pressures ranging from 0 to 15 mm Hg and after incubation in CO2-air mixtures at 5%, 10%, and 15% CO2 by volume. RESULTS: Tumor adhesion decreased significantly after CO2 insufflation. For all insufflation pressures, there was an increase in cell growth, apoptosis, and necrosis for the first 24 hours followed by a steady decline. High concentrations of CO2 (>5%) inhibited cell growth for only the first 48 hours. The effects of CO2 pneumoperitoneum on tumor-cell adhesion, growth inhibition, apoptosis, and necrosis were more prominent at high CO2 pressure (> or =15 mm Hg) and concentration (>5% CO2). However, insufflation pressure had a greater inhibitory effect on tumor growth than did CO2 concentration. High insufflation pressures and CO2 concentrations significantly decreased extracellular pH. CONCLUSION: The short-term effect of CO2 on TCC growth and apoptosis is complex. Overall, CO2 has a toxic effect on TCC and inhibits cell adhesion and growth. High CO2 concentrations (>5%) and high insufflation pressures (> or =15 mm Hg) are most effective in decreasing tumor-cell adhesion and growth.

Animals↗