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PubMed1991

Gas in gallstones: quantitative determinations and possible effects on fragmentation by shock waves.

The presence of gas in a gallstone can profoundly affect the ability of shock waves to fragment the stone by various mechanisms. In the present study, the aim was to determine the gas content of gallstones and determine if increasing the gas content of the stone affected the outcome of lithotripsy. Thirty human gallstones, transferred directly from gallbladder bile into sterile saline, were studied. The initial gas content of all stones was determined by differential weighing under saline before and after degassing. Eighteen gallstones were pairs; each pair was from a single patient and of similar size and composition. One gallstone of each of the pairs was exposed to air and the other was kept under saline. Then each of the paired gallstones was subjected to 1000 pulses at power level 3 (highest) in a Diasonics Therasonic lithotripter (Diasonics, Milpitas, CA). The volume of gas present at the beginning of the experiment in all groups of stones was 2.4 +/- 2.1 mm3, and 27% of all gallstones tested contained measurable amounts of gas initially. There was no significant difference in the volume of gas present in the paired stones at the beginning of the experiment (group A, 1 +/- 0.4 mm3; group B, 2 +/- 1 mm3). After group A stones were exposed to air, the gas content was significantly higher (36 +/- 18 mm3) than in the paired group B stones stored under saline (3 +/- 2 mm3; P less than 0.05). Stones exposed to air fragmented more easily than stones stored under saline. The mean number of pulses required to cause initial fragmentation was significantly lower in the group of stones exposed to air (22 +/- 7) compared with those stored under saline (610 +/- 139; P less than 0.05). The fragments were smaller and more numerous in the group of stones exposed to air than in those stored under saline. It is concluded that gas is present in some gallstones and that the efficacy of lithotripsy increases with increasing stone gas content. Our data suggest that alterations in the physical characteristics of gallstones can have profound effects on the outcome of lithotripsy.

Analysis of Variance↗

PubMed1999

[Anesthetic equipment: fresh gas delivery systems. II. Electronic systems].

OBJECTIVES: To analyse the design, functioning, benefits and drawbacks of electronic fresh gas delivery units (FGDUs) included in anaesthetic machines marketed in France in 1999. DATA SOURCES: Articles were obtained from a Medline review (1980-1999; search terms: anaesthetic machine, flowmeter, vaporizer), textbooks and personal files; specific data were also provided by manufacturers. STUDY SELECTION AND DATA EXTRACTION: The articles were analysed in considering the differences between mechanical and electronic FGDUs. DATA SYNTHESIS: Four anaesthetic machines out of 11 are equipped with electronic FGDUs. In comparison to mechanical units, they include the following benefits: wide range of accurate gas flow, especially in the low flow range, with analog and digital display; intermittent delivery of each gas, which is essential for automated gas delivery and quantitative anaesthesia or target controlled (FET vapor) inhalational anaesthesia; facilitated oxygen ratio control; possibility to print the gas and vapor flows on the automated anaesthetic record; interruption of gas flow when the main switch of the machine is set to off; and absence of risk for retropollution. Three FGDUs out of four are adapted for gas delivery to an accessory (ancillary) anaesthetic circuit. However, only one of them delivers a gas flow up to 30 L.min-1. The specificity of the ADU AS/3 (Datex-Ohmeda) is the bypass vaporizer included in the FGDU with an exchangeable vaporizing chamber (cassette). The specificity of the Julian (Dräger) is the delivery of fresh gas limited to the expiratory phase during mechanical ventilation. The specificity of the the FGDU from Kion (Siemens) is the possibility to act as an open circuit ventilator, similar to a Servoventilator. The specificity of the PhysioFlex is an FGDU included in the circle circuit, each gas and liquid anaesthetic being directly injected into the circuit. Data from the French medical device surveillance commission indicate that the main failures occur in the power supply device and the microprocessor.

Anesthesia, Inhalation↗

PubMed1997

Effects of gas flow management on postintubation end-tidal anesthetic concentration and operating room pollution.

STUDY OBJECTIVE: To study how different anesthetic practices during the transition from anesthetic delivery by mask to endotracheal intubation affect end-tidal postintubation anesthetic concentration and operating room (OR) pollution. DESIGN: Prospective study. SETTING: Anesthesia research laboratory. MEASUREMENTS AND MAIN RESULTS: We studied four gas flow management practices: practice vaporizer off, only the anesthetic vaporizer was turned off; all off, oxygen (O2), nitrous oxide (N2O), and the vaporizer were turned off; gas off: O2 and N2O were turned off; and all on: neither the gas flows nor the vaporizer were turned off. A model of inhalational anesthetic induction was simulated by using an adult circle system attached to a reservoir bag ("artificial lung"). By using a fixed gas flow, we achieved an end-tidal N2O (ETN2O) concentration of 70% and end-tidal halothane (ETHal) concentration of 3%, then stopped mechanical ventilation and performed the four practices for a 30-second "intubation" period. During this time, the reservoir bag was disconnected from the circuit, and the gas volume exiting the circuit (pollution volume) was measured. After this 30-second disconnect period, the bag was reconnected to the anesthetic circuit, and the original ventilation, gas flows, and vaporizer setting were resumed. The anesthetic concentrations were measured at 10, 20, and 30 seconds after reconnection. For the vaporizer off practice, ETHal was low and did not return to equilibrium within 30 seconds (p < 0.05); ETN2O clinically was unaltered. In the all off practice, anesthetic concentrations were below equilibrium at 10, 20, and 30 seconds (p < 0.05). For the gas off practice, ETHal was slightly below equilibrium at all times; ETN2O was below equilibrium at 10, 20, and 30 seconds (p < 0.05). In the all on practice, end-tidal anesthetic concentrations were unchanged when compared with equilibrium (p > 0.05). Pollution volumes in the vaporizer off and all on practices were ten-fold higher than in the all off and gas off practices (p < 0.05). CONCLUSION: In a mechanical model of anesthetic induction, turning the gas flows off before "intubation" and leaving the vaporizer on (the gas off practice) maintained "postintubation" end-tidal drug concentrations close to "preintubation" equilibrium and minimized OR pollution.

Air Pollution, Indoor↗

PubMed2001

A massive reservoir of low-excitation molecular gas at high redshift.

Molecular hydrogen (H2) is an important component of galaxies because it fuels star formation and the accretion of gas onto active galactic nuclei (AGN), the two processes that can generate the large infrared luminosities of gas-rich galaxies. Observations of spectral-line emission from the tracer molecule carbon monoxide (CO) are used to probe the properties of this gas. But the lines that have been studied in the local Universe-mostly the lower rotational transitions of J = 1 --> 0 and J = 2 --> 1-have hitherto been unobservable in high-redshift galaxies. Instead, higher transitions have been used, although the densities and temperatures required to excite these higher transitions may not be reached by much of the gas. As a result, past observations may have underestimated the total amount of molecular gas by a substantial amount. Here we report the discovery of large amounts of low-excitation molecular gas around the infrared-luminous quasar APM08279+5255 at redshift z = 3.91, using the two lowest excitation lines of 12 CO (J = 1 --> 0 and J = 2 --> 1). The maps confirm the presence of hot and dense gas near the nucleus, and reveal an extended reservoir of molecular gas with low excitation that is 10 to 100 times more massive than the gas traced by the higher-excitation observations. This raises the possibility that significant amounts of low-excitation molecular gas may exist in the environments of high-redshift (z > 3) galaxies.

Astronomical Phenomena↗

PubMed2006

Detection of sulfur-free odorants in natural gas using ion mobility spectrometry.

Beside the primary motivation of the public gas suppliers for odorizing natural gas with a sulfur-free odorant, which relates to the image of the environment-friendly fuel, natural gas, competing with low-sulfur heating fuel and diesel, a question of crucial importance of how to detect such sulfur-free odorants comes up. Concerning the replacement of sulfur-containing by sulfur-free odorization, the availability of a fast and sensitive detection method that can, further, be used on-site plays a key role. The minimum concentration of the new sulfur-free odorant Gasodor S-Free (S-Free) in natural gas should be added at a level of at least 8.8 mg m(-3) to assure a significant warning smell. Therefore, a dynamic range between 0 and approx. 25 mg m(-3) must be realised in the rather complex matrix of natural gas. By means of a handheld ion mobility spectrometer, the odorant content in natural gas is determined within less than 80 s total analysis time directly at the gas pipe. The concentration of S-Free is monitored between 4 and 23 mg m(-3) respecting the quality of the natural gas (high- and low-caloric gas). Results of the validation using a gas chromatograph as a reference standard will be discussed in detail.

Fossil Fuels↗

PubMed2005

Origin of gas retention and symptoms in patients with bloating.

BACKGROUND & AIMS: Patients reporting abdominal bloating exhibit impaired tolerance to intestinal gas loads. The aim of this study was to identify the gut compartment responsible for gas retention. METHODS: In 30 patients predominantly reporting abdominal bloating (24 with irritable bowel syndrome and 6 with functional bloating) and 22 healthy subjects, gas (nitrogen, carbon dioxide, and oxygen) was infused into the intestine for 2 hours while measuring rectal gas outflow. First, in 12 patients and 10 healthy subjects, gas transit (24 mL/min jejunal infusion labeled with 74 MBq bolus of 133 Xe) was measured by scintigraphy. Second, in groups of patients and healthy subjects, the effects of gas infusion (12 mL/min) in the jejunum versus ileum, jejunum versus cecum, and jejunum versus sham infusion (n=6 each) were compared by paired tests. RESULTS: In patients, total gut transit of gas was delayed (50% clearance time, 33 +/- 4 min vs 23 +/- 4 min in healthy subjects; P <.05) owing to impaired small bowel transit (50% clearance time, 20 +/- 2 min vs 12 +/- 3 min in healthy subjects; P <.05), whereas colonic transit was normal (50% clearance time, 13 +/- 2 min vs 11 +/- 2 min in healthy subjects; not significant). Furthermore, jejunal gas infusion in patients was associated with gas retention (329 +/- 81 mL vs 88 +/- 79 mL in healthy subjects; P <.05), whereas direct ileal or colonic infusion was not (61 +/- 103 mL and -143 +/- 87 mL retention, respectively). CONCLUSIONS: In patients reporting bloating, the small bowel is the gut region responsible for ineffective gas propulsion.

Adult↗

PubMed1975

The role of intestinal gas in functional abdominal pain.

A washout technic with intestinal infusion of an inert gas mixture was used to study the relation of gas to functional abdominal symptoms. The volume of gas in the intestinal tract (176 plus or minus 28 ml S.E.M.) of 12 fasting patients with chronic complaints of excess gas did not differ significantly (P greater than 0.10) from that of 10 controls (199 plus or minus 31 ml). Similarly, there was no difference in the composition or accumulation rate of intestinal gas. However, more gas tended to reflux back into the stomach in patients who complained of abdominal pain during infusion of volumes of gas well tolerated by controls. Six patients with severe pain during the study had intestinal transit times of gas (40 plus or minus 6 minutes S.E.M.) that were significantly (P less than 0.05) longer than those of the control group (22 plus or minus 3 minutes). Thus, complaints of bloating, pain and gas may result from disordered intestinal motility in combination with an abnormal pain response to gut distention rather than from increased volumes of gas.

Abdomen↗

PubMed2005

Effect of formaldehyde gas exposure in a murine allergic contact hypersensitivity model.

To clarify the effect of formaldehyde (FA) gas exposure on contact hypersensitivity (CHS), CHS reactions against 2,4,6-trinitrochlorobenzene (TNCB) was studied in BALB/c mice with a low dose of FA gas exposure. The TNCB-induced CHS reactions were slightly suppressed by the FA gas exposure immediately after sensitization, whereas they were significantly enhanced and prolonged in mice continuously exposed to FA gas before and after sensitization. We showed that exposure to FA gas enhanced the Th2 dominant responses in draining lymph node (LN) in early stage of CHS. In contrast, T cell subsets and their intracellular cytokine production in the draining LN were similar during the early stage of CHS by FA gas exposure during the sensitization phase. The percentage of CD8+ T cells was increased, and the percentage of CD4+CD25+ T cells was decreased in the FA gas-exposed group at 72 hr after elicitation. These results indicate that FA gas-exposed might influence regulatory T cells. Furthermore, in the chronic CHS model that was repetitively elicited with TNCB, more intensive and prolonged CHS reactions, and increased numbers of mast cells were found in the FA gas-exposed group at 4 hr after elicitation than in the control group, FA gas exposure may alter the intensity of allergic CHS.

Administration, Cutaneous↗

PubMed1976

An experimental study of gaseous homeostasis and the Magill circuit using low fresh gas flows.

Gas concentrations and ventilation levels have been measured within a conventional Magill circuit when conscious volunteers breathed a non-narcotic gas mixture at varying fresh gas flows. When evidence of rebreathing of alveolar gas was detected, the fresh gas flow was kept constant until a steady state developed. All subjects showed evidence of rebreathing when the fresh gas flow approached the predicted alveolar ventilation levels. A variety of subject-circuit interactions was seen and shown to be precipitated by naturally occurring breath-to-breath variations in ventilation. A single large breath could perturb the system. This could have a temporary effect, when the fresh gas flow was sufficient to wash the increased aliquot of expired carbon dioxide from the circuit. At other times a progressive response occurred as ventilatory stimulation as a result of the increased inspired carbon dioxide concentrations caused alveolar gas to reach the reservoir bag and converted the system behaviour from that of a simple added deadspace to that of a total mixing device. Whilst marked changes occurred commonly in both ventilation and inspired gas concentrations, only slight changes in end-tidal gas concentrations occurred.

Anesthesia, Inhalation↗

PubMedDate not supplied

The measurement of myocardial tissue gas tensions by mass spectrometry.

The mass spectrometer is a well established tool for the measurement of the partial pressures of gases in respiratory gas mixtures and in flowing blood. Only recently has mass spectrometry been applied to the measurement of gas tensions in tissue. Both blood and tissue gas tension measurements by mass spectrometry were made possible by the development of a special sampling catheter surrounded at its tip by a gas--but not liquid--permeable membrane. The partial pressure of each gas at the external surface of the membrane determines the flow of that gas across the membrane which, in turn, is measured by the mass spectrometer. The use of a Teflon membrane permits tissue measurements because its low permeability to gases reduces the sampling rate of gas molecules with the result that the depletion of gas molecules in the tissue surrounding the membrane is minimal. Mass spectrometry is the only technique whereby it is possible to measure regional tissue pO2 and pCO2 and other gas tensions simultaneously and continuously. One application of mass spectrometric tissue gas tension measurements is the monitoring of myocardial ischemia through measurements of myocardial tissue pO2 and pCO2. We have reviewed the work of others and ourselves in this field.

Adenosine Triphosphate↗

PubMed2002

Complications of general anesthesia using nitrous oxide in eyes with preexisting gas bubbles.

PURPOSE: To present the visual and anatomical outcomes for patients with intraocular gas placed during vitreoretinal surgery who subsequently underwent surgery wherein general anesthesia with nitrous oxide was used. METHODS: The authors reviewed the charts of patients who had undergone vitreoretinal surgery where a long-acting gas tamponade had been used. These patients underwent additional surgery for a variety of reasons at five different institutions and had nitrous oxide used during general anesthesia. The authors reviewed the preoperative and postoperative findings for patients receiving nitrous oxide following vitreoretinal surgery with gas tamponade. RESULTS: The authors reviewed findings for five eyes of five patients. All eyes that underwent general anesthesia using nitrous oxide had significant preexisting intraocular gas bubbles ranging from 40% to 90%, and the surgical procedures lasted from 1 to 4 hours. These eyes were followed from 2 months to 9 years (median follow-up, 4 years). Four of five eyes had a final vision of 20/200 or worse and significant optic atrophy at the time of the last follow-up examination. Three eyes had no light perception. CONCLUSION: The use of nitrous oxide during general anesthesia in gas-filled eyes may have disastrous visual results caused by gas expansion and elevated intraocular pressure. Patients must be advised of the potentially catastrophic results of undergoing general anesthesia before their intraocular gas bubble has resorbed. The use of nitrous oxide for patients with intraocular gas should be avoided. It may be prudent for patients with intraocular gas to wear notification bracelets warning anesthesiologists about the presence of intraocular gas lest emergency surgery be needed by a patient unable to advise anesthesia personnel about the potential danger.

Anesthesia, General↗

PubMed1998

Structural characteristics of halobacterial gas vesicles.

Gas vesicle formation in halophilic archaea is encoded by a DNA region (the vac region) containing 14 different genes: gvpACNO and gvpDEFGHIJKLM. In Halobacterium salinarum PHH1 (which expresses the p-vac region from plasmid pHH1), gas vesicles are spindle shaped, whereas predominantly cylindrical gas vesicles are synthesized by the chromosomal c-vac region of H. salinarum PHH4 and the single chromosomal mc-vac region of Haloferax mediterranei. Homologous complementation of gvp gene clusters derived from the chromosomal c-vac region led to cylindrical gas vesicles in transformants and proved that the activity of the c-gvpA promoter depended on a gene product from the c-gvpE-M DNA region. Heterologous complementation experiments with transcription units of different vac regions demonstrated that the formation of chimeric gas vesicles was possible. Comparison of micrographs of wild-type and chimeric gas vesicles indicated that the shape was not exclusively determined by GvpA, the major structural protein of the gas vesicle wall. More likely, a dynamic equilibrium of several gvp gene products was responsible for determination of the shape. Transmission electron microscopy of frozen hydrated, wild-type gas vesicles showed moiré patterns due to the superposition of the front and back parts of the ribbed gas vesicle envelope. Comparison of projections of model helices with the moiré pattern seen on the cylindrical part of the gas vesicles provided evidence that the ribs formed a helix of low pitch and not a stack of hoops.

Archaeal Proteins↗

PubMed1988

Trapping of gas mixtures by amorphous water ice.

Our studies on gas trapping in amorphous water ice at 24-100 K were extended, by using mixtures of CH4, CO, N2, and Ar, rather than single gases. In 1:1 gas:(water vapor) mixtures, the competition among these gases on the available sites in the ice showed that the trapping capacity for the various gases is determined not only by the structure and dynamics of the ice, but is also influenced by the gas itself. Whereas at 24-35 K all four gases are trapped in the ice indiscriminantly, at 50-75 K there is a clear enhancement, in the order of CH4 > CO > N2 > or approximately Ar. This order is influenced by the gas-water interaction energy, the size of the trapped gas atom or molecule, the type of clathrate-hydrate formed (I or II) and, possibly, other factors. It seems that the gas can be trapped in the amorphous ice in several different locations, each being affected in a different way by the deposition temperature and gas composition. Once a gas atom or molecule is trapped in a specific location, it is predestined to emerge in one of eight different temperature ranges, which are associated with changes in the ice. The experimentally observed enhancements, together with the findings on the gas composition of comet Halley, might enable an estimation of the gas composition in the region of comet formation.

Argon↗

PubMed1996

Gas leakage and the laryngeal mask airway. A comparison with the tracheal tube and facemask during spontaneous ventilation using a circle breathing system.

The ability of the laryngeal mask airway, tracheal tube and facemask to provide a leak free seal in a clinical setting was assessed by measuring the minimal fresh gas flows needed in a closed circle system during spontaneous ventilation on 60 subjects. The fresh gas flow was reduced until no spillage occurred from the pop-off valve. This fresh gas flow was taken to represent the sum of gas uptake by the subject and gas leakage from the circuit. The median fresh gas flow after 20 minutes was 350 ml.min-1 in the laryngeal mask airway group, 350 ml.min-1 in the tracheal tube group and 450 ml.min-1 in the facemask group. The fresh gas flow required for the facemask group was significantly higher than that for the laryngeal mask airway or tracheal tube groups (p < 0.01). There was no significant difference between the fresh gas flows required for the tracheal tube and laryngeal mask airway group. We conclude that the laryngeal mask airway provides as good a gas tight seal as a tracheal tube in this context and would be of benefit in reducing anaesthetic gas pollution.

Adult↗

PubMed2006

Modulation of intestinal gas dynamics in healthy human volunteers by the 5-HT receptor agonist tegaserod.

OBJECTIVES: Bloating in irritable bowel syndrome (IBS) may result from impaired intestinal gas transit and is reduced by the 5-HT4 agonist tegaserod. Abnormal serotonergic function underlies many IBS symptoms, but the role of 5-HT4 pathways in regulating gas dynamics under healthy conditions is unexplored. We hypothesized that 5-HT4 activation by tegaserod stimulates gas transit in healthy individuals. METHODS: Sixteen normal volunteers underwent jejunal perfusion of gas mixtures (88% N2, 5.5% O2, 6.5% CO2) at 11.2 mL/min x 3 h under control conditions and 3 h after oral tegaserod 6 mg on separate days. Gas collected from an intrarectal catheter was quantified using a barostat. RESULTS: Under control conditions, gas evacuation after a lag period (1,959 +/- 428 s) was predominantly pulsatile with expulsion of 1,984 +/- 90 mL. A mean of 29 +/- 2 boluses with volumes of 72 +/- 5 mL were expelled. In 10 subjects with physiologic degrees of gas retention in control studies (248 +/- 73 mL), tegaserod increased expulsion from 1,768 +/- 73 to 1,973 +/- 37 mL and decreased retention to 43 +/- 37 mL (p < 0.05). Total volumes expelled as boluses were greater after tegaserod (1,708 +/- 73 vs 1,846 +/- 59 mL, p < 0.05) from increased bolus numbers in four subjects and increased bolus volumes in seven. Nonpulsatile continuous flow tended to increase with tegaserod (43 +/- 7 vs 126 +/- 43 mL, p= 0.10). Tegaserod did not increase evacuation in individuals without physiologic gas retention. CONCLUSIONS: The 5-HT4 agonist tegaserod promotes evacuation of jejunally perfused gas mixtures in healthy humans. These findings provide the foundation for future investigations into use of 5-HT4 agonists in conditions of pathologic gas retention.

Administration, Oral↗

PubMed2000

Observation and quantification of gas bubble formation on a mechanical heart valve.

Clinical studies using transcranial Doppler ultrasonography in patients with mechanical heart valves (MHV) have detected gaseous emboli. The relationship of gaseous emboli release and cavitation on MHV has been a subject of debate in the literature. To study the influence of cavitation and gas content on the formation and growth of stable gas bubbles, a mock circulatory loop, which employed a Medtronic-Hall pyrolytic carbon disk valve in the mitral position, was used. A high-speed video camera allowed observation of cavitation and gas bubble release on the inflow valve surfaces as a function of cavitation intensity and carbon dioxide (CO2) concentration, while an ultrasonic monitoring system scanned the aortic outflow tract to quantify gas bubble production by calculating the gray scale levels of the images. In the absence of cavitation, no stable gas bubbles were formed. When gas bubbles were formed, they were first seen a few milliseconds after and in the vicinity of cavitation collapse. The volume of the gas bubbles detected in the aortic track increased with both increased CO2 and increased cavitation intensity. No correlation was observed between O2 concentration and bubble volume. We conclude that cavitation is an essential precursor to stable gas bubble formation, and CO2, the most soluble blood gas, is the major component of stable gas bubbles.

Carbon Dioxide↗

PubMed2005

Impaired reflex control of intestinal gas transit in patients with abdominal bloating.

BACKGROUND: Patients with abdominal bloating and distension exhibit impaired transit of intestinal gas which may lead to excessive gas retention and symptoms. Furthermore, we have previously shown that intestinal gas transit is normally accelerated by rectal distension. We hypothesise that in patients with functional bloating this modulatory mechanism fails and impairs gas transit. METHODS: In 12 healthy subjects and eight patients with abdominal bloating we compared, by paired studies, the effect of rectal versus sham distension on intestinal gas transit. Gas was infused into the jejunum (12 ml/min) for three hours with simultaneous perfusion of lipids into the duodenum (Intralipid 1 kcal/min) while measuring evacuation of gas per rectum. RESULTS: In healthy subjects, duodenal lipid infusion produced gas retention (409 (68) ml) which was prevented by rectal distension (90 (90) ml; p<0.05 v sham distension). In contrast, rectal distension in patients with abdominal bloating failed to reduce lipid induced gas retention (771 (217) ml retention during rectal distension v 730 (183) ml during sham distension; NS; p<0.05 v healthy controls for both). CONCLUSION: Failure of distension related reflexes impairs intestinal gas propulsion and clearance in patients with abdominal bloating.

Abdomen↗

PubMed2001

Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome.

BACKGROUND: Patients with irritable bowel syndrome (IBS) frequently complain of excessive gas but their fasting volume of intestinal gas is apparently normal. We hypothesised that the pathophysiological mechanism involved may be impairment of intestinal gas transit. AIM: To investigate intestinal gas transit and tolerance in IBS patients compared with healthy subjects. METHODS: A gas mixture (N(2), O(2), and CO(2) in venous proportions) was infused into the jejunum of 20 patients with IBS and 20 healthy controls at 12 ml/min for four hours. Gas evacuation, initially flatus from the anus (two hours) and then intrarectally (two hours), was continuously recorded. Symptom perception (0-6 scale) and abdominal distension were measured at 10 minute intervals. RESULTS: After two hours of external gas (flatus) collection, 18 of 20 IBS patients had developed gas retention (>400 ml), increased gastrointestinal symptoms (score >3), or abdominal distension (>3 mm girth increment) compared with only four of 20 control subjects. During intrarectal gas collection, 13 of 17 patients still exhibited abnormal responses. CONCLUSION: A large proportion of patients with IBS can be shown to have impaired transit and tolerance of intestinal gas loads. This anomaly may represent a possible mechanism of IBS symptoms, specifically pain and bloating.

Abdomen↗