Residual intraperitoneal carbon dioxide gas following laparoscopy for adnexal masses: Residual gas volume assessment and postoperative outcome analysis

The aim of the current study was to directly investigate whether active gas suction reduces intraperitoneal residual carbon dioxide and to analyze the effect of active gas suction on postoperative pain after laparoscopic cholecystectomy. This prospective, randomized clinical study included patients between 19 and 65 years of age with gallbladder disease who were eligible for elective laparoscopic cholecystectomy. Patients were allocated into either the natural evacuation group (NE group) or the active suction group (AS group). In the AS group, active suction was applied by inserting the laparoscopic suction irrigation device through a 5-mm trocar for 60 seconds at the end of surgery. A chest X-ray was taken at postoperative Day 1, and the residual intraabdominal gas volume was measured. Perioperative data including pain score and analgesic requirement were collected. Thirty-nine patients were allocated to the NE group, and 36 were allocated to the AS group. There was no statistically significant difference between the two groups in terms of demographic data and operative findings. However, a significant difference was observed in the residual intraperitoneal gas volume, with 15.9±6.8 mL in the NE group and 6.7±4.0 mL in the AS group (P<.001). Significant differences were also observed in the pain scores measured 6 hours after surgery, on postoperative Day 1, and on postoperative Day 2. Active gas suction is a very simple procedure that is safe and feasible. Performing this procedure significantly decreases the residual intraperitoneal gas volume and postoperative pain after laparoscopic surgery.

Background: Laparoscopic surgery has many advantages compared with conventional methods and may allow a significant reduction in postoperative pain and analgesic consumption. Nevertheless, some patients still experience significant pain. Therefore, many clinicians have tried various methods to reduce of postoperative pain. We investigated degrees of postoperative pain and the incidences of shoulder pain versus the different methods of gas removal after laparoscopic surgery. Methods: Sixty ASA class I or II patients were included in this study. In Group A (Control group, n = 20), residual carbon dioxide was removed by the classic method without a drain tube. In Group B (Suction group, n = 20), residual carbon dioxide was removed using a suction device aggressively without a drain tube. In Group C (Drain group, n = 20), residual carbon dioxide was removed by the classic method with a drain tube. The intensities of abdominal and shoulder pain were assessed 1, 6, 24 and 48 hours after surgery using a visual analog scale (VAS) and a verbal rating scale (VRS). We also assessed the mean hospital stay for the three groups. Results: The abdominal pain scores (VAS and VRS) at 1 hour after surgery and the incidence of shoulder pain, epigastria pain and flank pain were significantly higher in Group A than in the other groups for 1hour after surgery (P ＜ 0.05). Mean hospital stay was significantly longer for group C. Conclusions: After laparoscopic surgery, the active removal of residual carbon dioxide may be a simple and safe method that significantly reduces postoperative shoulder and abdominal pain.

Background: Postoperative abdominal and shoulder pains after laparoscopic cholecystectomy (LC) are the most frequent complaints and are related to delayed recovery. There is a strong correlation between the residual gas volume and the severity of pain following various laparoscopic procedures. We aimed to investigate the effects of aspiration of residual gas on postoperative outcomes and pain following LC. Patients were randomly assigned to either the active gas reduction group (Group 1, n=105) or the control group (Group 2, n=95). After completion of the operative procedures, residual gas was aspirated with a flexible cannula in Group 1. In Group 2, gas release from the abdomen was performed using the port site by opening the gas tap only. The demographic data, operation time, insufflated CO2 volume during the operation, hospitalization period, and time to return to daily activities were recorded. Postoperative shoulder and abdominal pain assessment was performed using a numerical pain intensity scale (NPIS) at 1 hour, 24 hours, 3 days, and 7 days postoperatively. There was no statistically significant difference between the groups in terms of demographic data, operative findings, and clinical outcomes. NPIS scores for shoulder pain at 1 hour and 24 hours were significantly lower in Group 1 (P=.001 and P=.021, respectively). However, there were no significant differences in the NPIS scores for shoulder and abdominal pain following 24 hours. No differences were found in the hospitalization duration and time to return to daily activities data (P>.05). Active aspiration of the residual gas just before the removal of the trochars is a simple procedure and leads to a more comfortable hospital stay for patients.

After laparoscopic surgical procedures, residual gas in the abdominal cavity can cause post-operative pain, which is commonly located in the shoulder region. Previous studies suggested that post-laparoscopy pain can be prevented by active suctioning of intraabdominal gas at the end of surgery. This randomized controlled trial (registered at DRKS 00,023,286) compared active suctioning versus manual compression in their ability to reduce pain after laparoscopic cholecystectomy. Patients scheduled for laparoscopic cholecystectomy were eligible for trial participation. The primary outcome measure was post-operative pain intensity after 12h. All the patients were examined by MRI scanning to quantify the intraabdominal gas volume after the intervention. As planned, 60 patients were recruited. The two groups (n = 30 each) were very similar at the end of surgery. Active suctioning reduced the amount of residual pneumoperitoneum more than simple compression (median volume 1.5 versus 3.0ml, p = 0.002). The primary outcome measure, abdominal pain after 12h, was slightly lower in the intervention group (- 0.5 points, 95% confidence interval + 0.5 to - 1.7), but without reaching statistical significance (p = 0.37). After 12h, shoulder pain was present in 10 patients in each group (p = 1.0). Independent of group assignment, however, residual gas volume was significantly associated with higher pain intensity. Active suctioning appears to have only a minor preventive effect on post-laparoscopy pain, probably because evacuation of the pneumoperitoneum remains incomplete in some patients. Other more effective maneuvers for gas removal should be preferred.

The apparent diffusion coefficient (ADC) of hyperpolarized (HP) gases is a parameter that reflects changes in lung microstructure. However, ADC is dependent on many physiological and experimental variables that need to be controlled or specified in order to ensure the reliability and reproducibility of this parameter. A single breath-hold experiment is desirable in order to reduce the amount of consumed HP gas. The application of a positive end-expiratory pressure (PEEP) causes an increase in the residual gas volume. Depending on the applied PEEP, the ratio between the incoming and residual gas volumes will change and the ADC will vary, as long as both gases do not have the same diffusion coefficient. The most standard method for human applications uses air for breathing and a bolus of pure HP (3)He for MRI data acquisition. By applying this method in rats, we have demonstrated that ADC values are strongly dependent on the applied PEEP, and therefore on the residual gas volume in the lung. This outcome will play an important role in studies concerning certain diseases, such as emphysema, which is characterized by an increase in the residual volume. Ventilation with an oxygen-helium mixture (VOHeM) is a proposed single breath-hold method that uses two different gas mixtures (O(2)-(4)He for ventilation and HP (3)He-N(2) for imaging). The concentration of each gas in its respective mixture was calculated in order to obtain the same diffusion coefficient in both mixtures. ADCs obtained from VOHeM are independent of PEEP, thus minimizing the effect of the different residual volumes.

Modeling and optimization of shutdown process of combined cycle gas turbine under limited residual natural gas

ABSTRACTWet pack pears in retort pouches were studied for six months. Four selected residual gas volumes [10, 15, 20 and 30 cubic centimeters (cc)] were used to determine the influence of residual gas volume on physicochemical and sensory attributes. Three storage temperatures (4.4, 26.7 and 37.8C) were used to carry out an accelerated shelf‐life study. Residual gas of 30 cc promoted faster darkening and higher ascorbic acid degradation than the rest of the volumes studied (α≤ 0.01). No significant effect of residual gas volume was found on any other attribute analyzed. Temperature accelerated the consumption of remaining oxygen in the pouches, degradation of ascorbic acid, formation of 5‐hydroxymethyl‐2‐furaldehyde (HMF) and 2‐furaldehyde, and softening of pears. Calculated activation energies (Ea) for HMF and 2‐furaldehyde formation, ascorbic acid, and color degradation were 35, 31.1, 29.8, and 10.4 kcal/mol, respectively. Residual gas volume of 20 cc was the maximum volume studied that accomplished the desired shelf‐life for this product.

Following laparoscopic surgery, residual carbon dioxide (CO2) trapped between the liver and the diaphragm induces phrenic nerve irritation and causes more patient discomfort than pain at the incision site. Although the pulmonary recruitment maneuver can mechanically remove residual CO2 and reduce pain, its effects occur only immediately after the operation and disappear later. Intraperitoneal normal saline infusion, another procedure, washes out CO2 with a physiologic buffer system and maintains longer pain relief. These 2 interventions are mediated through different mechanisms and act in different phases. This randomized controlled trial (RCT) tested the hypothesis that combining the pulmonary recruitment maneuver and intraperitoneal normal saline infusion would reduce postlaparoscopic shoulder and upper abdominal pain. Subjects were randomly assigned to the combined intervention or a control group receiving only passive deflation at the end of the procedure. Data for 100 patients were included in the analysis, 50 in the intervention group and 50 in the control group. The primary study end point was patient-reported postlaparoscopic upper abdominal pain and shoulder pain measured using a visual analog scale. Ratings for pain were obtained 12, 24, and 48 hours after surgery. The incidence of laparoscopic-induced shoulder pain at 12, 24, and 48 hours was lower in the intervention group (54%, 46%, and 30%, respectively) compared with the control group (72%, 70%, and 50%, respectively; P = 0.008, P = 0.001, and P = 0.004, respectively). To reduce the incidence of shoulder pain, the number needed to treat was 6 (95% confidence interval [CI], 4–21) at 12 hours, 5 (95% CI, 3–10) at 24 hours, and 5 (95% CI, 4–15) at 48 hours. At 12, 24, and 48 hours after surgery, the incidence of laparoscopic-induced upper abdominal pain also was lower in the intervention group (78%, 72%, and 58%, respectively) than that in the control group (92%, 90%, and 70%, respectively; P = 0.006, P = 0.001, and P = 0.077, respectively). These data show that the combined pulmonary recruitment maneuver and intraperitoneal normal saline infusion significantly reduce postlaparoscopic shoulder and upper abdominal pain. This intervention is inexpensive and easy to implement in daily clinical practice.

Gas–water two-phase flow in porous media is vital in groundwater management and hydrocarbon development, yet most experiments use small cores (5–10 cm) or etched micro-models. These studies often overlook the quantitative characterization of residual gas, long-distance gas–water flow behavior, and effects of gas–water flow on pore structure. This study presents a series of 3 m-long artificial unconsolidated sandstone models with permeabilities of 5, 10, 30, 50, and 100 mD, fabricated via rock–electric testing techniques to simulate edge-water invasion in gas reservoirs. The results indicate that (1) by adjusting clay content, cementing agents, grain size, and sand mix, artificial cores achieve permeability, porosity, cementation strength, sensitivity, and pore structure similar to natural cores; this approach addresses the sampling challenge from unconsolidated sandstone. (2) During long-distance gas–water flow, pressure drops rapidly in the gas–water transition zone. As permeability increases, the zone shifts downstream and becomes narrower. (3) The flow of gas–water causes a large number of particles to gather near the gas–water interface and block the throat, and effective stress on unconsolidated sandstone intensifies this blockage effect. (4) Residual gas exists in the forms of dead-end trapped gas, bypass trapped gas, and snap-off trapped gas. The residual gas volume is mainly controlled by gas saturation and pressure, but the largest amount of residual gas accumulates near the gas–water interface. This study addresses the research gap in understanding long-distance gas–water flow and presents a novel experimental method for unconsolidated porous media.

Purpose To observe the efficacy and safety of pars plana vitrectomy (PPV) combined with filtered air tamponade in the treatment of rhegmatogenous retinal detachment (RRD) with inferior retinal breaks. Methods This retrospective study included 20 patients (20 eyes) with inferior retinal breaks in RRD; all underwent PPV combined with filtered air tamponade. Preoperative examinations included BCVA, IOP, anterior segment, fundus and locations, numbers, and sizes of retinal breaks and ocular B-mode ultrasonography. Postoperative examinations included BCVA, IOP, residual gas volume, retinal reattachment, and complications. Results After follow-up for 1 year, the primary retinal reattachment rate was 95% and the final reattachment rate was 100%. Pre- and postoperative BCVA averaged 1.51 ± 0.63 and 0.97 ± 0.58 logMAR, respectively; the difference was statistically significant (P < 0.001). Average pre- and postoperative IOP were not statistically different. The average volume of residual gas on the first day after the surgery was 77.5%; the gas was absorbed in all patients within 2 weeks; no significant postoperative complications were observed. Conclusion PPV combined with filtered air tamponade is a safe and effective treatment for RRD with inferior retinal breaks. Notably, the retinal reattachment rate is high, gas absorption is rapid, and incidence of complications is low.

Residual intra-peritoneal gas may be associated with post-laparoscopic shoulder pain (PLSP), which is a frequently and disturbance compliant after surgery. Herein, we aimed to examine whether expiring residual gas via a surgical drain reduces the frequency and intensity of PLSP in the first day after laparoscopic cholecystectomy. 448 participants were enrolled in this prospective cohort study. The incidence and severity of PLSP after surgery were recorded. Of these, the cumulative incidence of PLSP in the drain group was lower particularly at the 12th postoperative hour (18.3% vs. 27.6%; P = 0.022), 24th postoperative hour (28.8% vs. 38.1%; P = 0.039), and throughout the first postoperative day (P = 0.035). The drain group had less severe PLSP (crude Odds ratio, 0.66; P = .036). After adjustment using inverse probability of treatment weighting, the drain group also had a significant lower PLSP incidence (adjusted hazard ratio = 0.61, P < 0.001), and less severe PLSP (adjusted odds ratio = 0.56, P < 0.001). In conclusion, the maneuver about passive force to expel residual gas, surgical drain use, contributes to reduce the incidence and severity of PLSP, suggesting that to minimize residual gas at the end of surgery is useful to attenuate PLSP.

Residual gas and storage conditions affect sensory quality of diced pears in flexible retortable pouches

BackgroundTo investigate whether human papillomavirus (HPV) infection is associated with primary lung cancer among the Fujian population.MethodsHPV infection was detected in 140 pairs of lung cancer tissues and matched paracancerous tissues by examining the 21 clinically relevant HPV types using a combination of viral highly conserved L1 region PCR amplification and specific probe reverse hybridization. Paired χ2 test was used to analyze differences in detection rates of HPV between lung cancer and paracancerous tissues. Differences in detection rates of HPV in lung cancer tissues were analyzed using χ2 test or the exact probability method. The rank sum test was used to analyze differences in the distributions of routine indices of blood and pulmonary function in lung cancer tissues between the HPV negative and positive groups.ResultsHPV infection was detected in 13 of the 140 tumor specimens and in 16 of the paired normal lung tissues. There was no significant correlation between HPV infection and lung cancer (P > 0.05). The diagnosed HPV infection rates did not differ significantly among lung cancer tissues with different stratification (P > 0.05). However, the platelet count, platelet pressure, residual gas volume, functional residual volume, and residual gas volume/lung total distribution may differ between HPV‐negative and HPV‐positive lung cancer tissues (0.000625 < P < 0.05).ConclusionsWe concluded that HPV infection may not be associated with the risk of primary lung cancer in the Fujian population. However, HPV infection may affect platelet and residual lung function in primary lung cancer patients.

Restriction of total lung capacity (TLC) is found in some obese subjects, but the mechanism is unclear. Two hypotheses are as follows: 1) increased abdominal volume prevents full descent of the diaphragm; and 2) increased intrathoracic fat reduces space for full lung expansion. We have measured total intrathoracic volume at full inflation using magnetic resonance imaging (MRI) in 14 asymptomatic obese men [mean age 52 yr, body mass index (BMI) 35-45 kg/m2] and 7 control men (mean age 50 yr, BMI 22-27 kg/m2). MRI volumes were compared with gas volumes at TLC. All measurements were made with subjects supine. Obese men had smaller functional residual capacity (FRC) and FRC-to-TLC ratio than control men. There was a 12% predicted difference in mean TLC between obese (84% predicted) and control men (96% predicted). In contrast, differences in total intrathoracic volume (MRI) at full inflation were only 4% predicted TLC (obese 116% predicted TLC, control 120% predicted TLC), because mediastinal volume was larger in obese than in control [heart and major vessels (obese 1.10 liter, control 0.87 liter, P=0.016) and intrathoracic fat (obese 0.68 liter, control 0.23 liter, P<0.0001)]. As a consequence of increased mediastinal volume, intrathoracic volume at FRC in obese men was considerably larger than indicated by the gas volume at FRC. The difference in gas volume at TLC between the six obese men with restriction, TLC<80% predicted (OR), and the eight obese men with TLC>80% predicted (ON) was 26% predicted TLC. Mediastinal volume was similar in OR (1.84 liter) and ON (1.73 liter), but total intrathoracic volume was 19% predicted TLC smaller in OR than in ON. We conclude that the major factor restricting TLC in some obese men was reduced thoracic expansion at full inflation.

Although combined cycle gas turbine (CCGT) has been utilized and studied intensively, little attention was paid on optimizing its shutdown process. Under limited residual natural gas, the optimization of shutdown process of CCGT becomes a problem needed to be solved, and no research has been conducted on solving this particular problem. In this study, the overall performance and characteristics of the shutdown process of CCGT were analyzed and modeled. This model was proposed to allocate gas consumption during shutdown process for creating maximum power generation and maximum economic benefit. Based on the shutdown process model, optimal shutdown scheme was proposed and proved, and optimizing algorithms were developed to facilitate the decision making procedure. The calculations of different load-up rates and load-off rates of CCGT showed that the total power generation is more relevant with the load-off rates rather than the load-up rates. When the residual natural gas volume assumed to be 105 m3, the shutdown optimization could generate an extra power of 28.41 MW⋅h and an extra profit of 4.79 million Yuan annually. This program was applied on three CCGTs in a power plant in Zhejiang Province, China, as a case study. The testing results proved that the obtained optimization scheme is technically stable and effective in the real working condition. Thus, the model and the optimization algorithms were also valid and feasible for potential applications.