Prospective, randomized, clinical trial on the effects of laparoscopic insufflation pressures on portal pressures in dogs.

OBJECTIVE: The adverse effects of intra-abdominal pressure from capnoperitoneum on cardiovascular and pulmonary systems have been well documented, but the effects on portal pressures in dogs with various insufflation pressures is poorly defined. The aim of the present study was to measure the effect of a range of insufflation pressures on the portal pressure, using direct pressure measurements in patients undergoing laparoscopy. STUDY DESIGN: Clinical randomized prospective study. ANIMALS: Nine client-owned dogs undergoing routine laparoscopy. METHODS: Two rounds of direct portal pressure assessments were performed, at insufflation pressures of 0, 6, 10, and 14 mmHg in a predetermined randomized sequence. The data were analyzed for effects of insufflation pressure, hemodynamic alterations, and round. A best-fit exponential model of the relationship between portal pressure and insufflation pressure was created. RESULTS: Portal pressure increased by 38% at 6 mmHg, 95% at 10 mmHg, and 175% at 14 mmHg compared to baseline. Portal pressure increased at an average rate of 7.45% per mmHg of insufflation pressure. Effects of weight, weight/insufflation pressure interaction, and round of insufflation were not statistically significant. No systemic hemodynamic adverse events were observed. CONCLUSION: Portal pressure increased as insufflation pressure increased. There was no clinically significant difference in baseline portal pressure between rounds of insufflation. CLINICAL SIGNIFICANCE: This exponential model of portal pressure supports the use of the minimum insufflation pressure to allow visualization during laparoscopy. The return of portal pressure to baseline following desufflation supports the comparison of portal pressure measurements before and after laparoscopic shunt attenuation.

Effect of insufflation pressure during transanal minimally invasive surgery on surgical complications with dissection of the rectal submucosa in canine cadavers.

OBJECTIVE: To determine ideal insufflation pressures during transanal minimally invasive surgery (TAMIS) in canine cadavers for rectal submucosal transection and incisional closure. ANIMALS: 16 canine cadavers. PROCEDURES: Cadavers were placed in lateral recumbency. Urinary catheters were placed to measure intra-abdominal pressure (IAP). A single access port was placed to establish a pneumorectum. Cadavers were placed in insufflation groups of 6 mmHg to 8 mmHg (group 1), 10 mmHg to 12 mmHg (group 2), or 14 mmHg to 16 mmHg (group 3). Defects in the rectal submucosa were created and closed with a unidirectional barbed suture. Duration for each procedure and subjective ease of identifying the transection plane and performing incisional closure were assessed. RESULTS: The single access port was successfully placed in dogs weighing 22.7 kg to 48 kg. The ease of each step of the procedure was not influenced by the insufflation pressure. The median surgical duration for group 1 was 740 seconds (range = 564 to 951 seconds), 879 seconds (range = 678 to 991 seconds) for group 2, and 749 seconds (range = 630 to 1,244 seconds) for group 3 (P = .650). The insufflation pressure increased the IAP (P = .007). Perforation of the rectum happened in 2 cadavers in group 3. CLINICAL RELEVANCE: The duration of each step of the procedure was not significantly influenced by insufflation pressure. Defining the dissection plane and performing resection was more challenging in the highest-pressure group. Rectal perforation occurred only with the 14 mmHg to 16 mmHg insufflation pressure. Single access port usage with TAMIS may provide a readily available, minimally invasive approach for the resection of rectal tumors in dogs.

Laparoscopic peritoneopericardial herniorrhaphy in 2 dogs.

Two peritoneopericardial hernias (PPDH) repaired laparoscopically are reported. Both PPDHs were approached with the dog in dorsal recumbency. Herniated organs (gallbladder and 2 liver lobes in Case 1 and omental fat in Case 2) were dissected and reduced. Hernias were closed in a 2-layer horizontal mattress pattern using 2-0 polyester (Case 1), and in a single-layer simple continuous pattern using 0 barbed polyglyconate (Case 2). Reduction and herniorrhaphy were achieved without conversion. Moderate to severe systemic hypotension was observed in both dogs which responded rapidly to reducing abdominal insufflation. Ten- and 7-month follow-up confirmed good clinical outcome in both dogs.

Herniorraphie péritonéo-péricardique laparoscopique chez deux chiens. Deux hernies péritonéopéricardiques (PPDH) réparées par laparoscopie sont rapportées. Les deux PPDHs ont été réalisées avec le chien en décubitus dorsal. Les organes herniés (vésicule biliaire et deux lobes hépatiques dans le cas 1 et graisse épiploïque dans le cas 2) ont été disséqués et réduits. Les hernies ont été fermées avec un patron de suture matelas horizontal à deux couches en utilisant du polyester 2-0 (cas 1) et avec un modèle de suture continu simple à une seule couche en utilisant du polyglyconate barbelé 0 (cas 2). La réduction et l'herniorraphie ont été réalisées sans conversion. Une hypotension systémique modérée à sévère a été observée chez les deux chiens qui ont répondu rapidement à la réduction de l'insufflation abdominale. Un suivi de dix et sept mois a confirmé de bons résultats cliniques chez les deux chiens.(Traduit par Dr Serge Messier).

Effects of combined one-lung ventilation and intrathoracic carbon dioxide insufflation on intrathoracic working space when performing thoracoscopy in dogs.

OBJECTIVE: To evaluate the effects of combining one-lung ventilation and carbon dioxide insufflation (OLV-CDI) on intrathoracic working space (determined by means of CT) during thoracoscopy in dogs and investigate conditions that could safely improve working space compared with OLV alone. ANIMALS: 6 healthy Beagles. PROCEDURES: Dogs were anesthetized, and right- or left-sided (n = 3/side) OLV was instituted. On the blocked side, a laparoscopic trocar sleeve was placed in the ninth intercostal space for CDI. CT was performed under 3 conditions: with OLV alone, with OLV-CDI at an intrapleural pressure (IPP) of 3 mm Hg, and with OLV-CDI at an IPP of 5 mm Hg. Working space volume (WSV), ventilation space volume (VSV), and thoracic cavity volume (TCV) were determined from CT images. RESULTS: With OLV-CDI at an IPP of 3 or 5 mm Hg, WSV and TCV were significantly increased, compared with values obtained during OLV alone. With OLV-CDI at an IPP of 5 mm Hg, VSV and Spo2 were significantly decreased, compared with values obtained during OLV alone. Additionally, contralateral pneumothorax was observed in 4 dogs at an IPP of 5 mm Hg. CLINICAL RELEVANCE: Combining OLV and CDI could provide a larger working space than OLV alone, even with an IPP of 3 mm Hg, in dogs of limited size. However, an evaluation of the effects on oxygenation and cardiovascular variables is needed before clinical use.

Assessment of laparoscopic working space in guinea pigs (Cavia porcellus) undergoing carbon dioxide insufflation at different intra-abdominal pressures.

OBJECTIVE: To evaluate pneumoperitoneal volumes (laparoscopic working space) in guinea pigs (Cavia porcellus) undergoing pneumoperitoneum via carbon dioxide insufflation at different intra-abdominal pressures (IAPs) (4, 6, and 8 mm Hg) and recumbencies (dorsal, right lateral, and left lateral). ANIMALS: Six 3- to 4-month-old sexually intact female Hartley guinea pigs. PROCEDURES: Guinea pigs were anesthetized, intubated, and had an abdominal insufflation catheter placed. A baseline abdominal CT scan was performed. Guinea pigs underwent insufflation, with each IAP given in a random order for 10 to 15 minutes with a washout period of 5 minutes between pressures. Abdominal CT scans were acquired at each IAP and at each recumbency. Pneumoperitoneal volumes were calculated using software. RESULTS: Increases in IAP increased working space significantly (P < .001). The 6- and 8-mm Hg pressures increased working space from 4 mm Hg by 7.3% and 19.8%, respectively. Recumbent positioning (P = .60) and body weight (P = .73) did not affect working space. Order of IAP had a significant (P = .006) effect on working space. One of the guinea pigs experienced oxygen desaturation and bradycardia at 6- and 8-mm Hg IAP. CLINICAL RELEVANCE: Although an increased working space occurred at 6 and 8 mm Hg compared to 4 mm Hg, further research is needed concerning the cardiovascular effects of pneumoperitoneum in guinea pigs to determine whether those higher IAPs are safe in this species. An IAP of 6 mm Hg can be considered for laparoscopic cannula placement, followed by a lower IAP for laparoscopic procedures.

Effect of pneumoperitoneum on gastrointestinal motility, pain behaviors, and stress biomarkers in guinea pigs (Cavia porcellus).

OBJECTIVE: To compare stress markers, gastrointestinal motility, and behavioral indicators of pain between guinea pigs undergoing pneumoperitoneum with carbon dioxide (CO2) and control guinea pigs. ANIMALS: Fourteen 4- to 5-month-old intact female Hartley guinea pigs. PROCEDURES: Guinea pigs were randomized to receive insufflation or serve as controls (anesthesia and abdominal catheter placement without insufflation), with 7 animals/group. Insufflated animals underwent 6 mm Hg of CO2 pneumoperitoneum for 30 minutes. Afterward, results for vital signs, blood glucose, fecal cortisol, appetite, fecal output, and behaviors (via video recording) were compared between the 2 groups. RESULTS: There was no difference between groups and over time for body temperature, heart rate, fecal output in grams, pellets consumed, blood glucose, and fecal cortisol. Guinea pigs that underwent insufflation had significantly more fecal pellets at 36 hours after the procedure. Several behaviors were expressed similarly between groups and over time, such as body turns, incomplete movement, rearing, lying down, drinking, and hiding. Coprophagy occurred less often in the insufflated versus noninsufflated group at 12 h postprocedure but was similar between groups at other time points. At 60 hours after the procedure, insufflated animals spent less time squinting compared to noninsufflated animals. Other behaviors were differentially expressed over time but not between treatments. CLINICAL RELEVANCE: Overall, there were no major differences in appetite, stress markers, and behaviors between insufflated and control guinea pigs. CO2 insufflation did not appear to cause undue pain or stress in guinea pigs and may be a reasonable technique to use during laparoscopy.

Intratracheal oxygen administration increases FIO2 and PaO2 compared with intranasal administration in healthy, standing horses.

OBJECTIVE: To evaluate the efficacy of 2 different oxygen delivery strategies-intranasal and tracheal insufflation-on the inspired fraction of oxygen (FIO2) in standing horses and to determine the time needed for arterial oxygen partial pressure (PaO2) equilibration. ANIMALS: 6 healthy adult horses. PROCEDURES: In this blinded, randomized crossover design study, horses were randomly assigned to receive oxygen via nasal cannula (group N) or transcutaneous tracheal catheter (group T). After placement of venous and arterial catheters, FIO2 was measured through a catheter placed into the distal portion of the trachea. After baseline measurements were obtained, horses received oxygen at up to 25 mL/kg/min for 1 hour via either intranasal or intratracheal catheter. The FIO2 and PaO2 were recorded at 5, 10, 15, 20, 25, 30, 45, and 60 minutes during and 5, 10, 15, 20, and 30 minutes after oxygen insufflation. Data were analyzed by use of a 2-way repeated measures ANOVA with Tukey-Kramer post hoc testing for pairwise comparisons (P < 0.05). RESULTS: During oxygen administration, FIO2 and PaO2 increased significantly when compared with baseline, resulting in significantly higher values for group T (37.7 ± 2.4%; 214.6 ± 18 mm Hg) than for group N (34.3 ± 3.9%; 184.1 ± 11 mm Hg). The equilibration time was less than 10 minutes. CLINICAL RELEVANCE: Intratracheal oxygen administration resulted in better oxygenation than nasal insufflation and should therefore be considered in standing horses that are experiencing severe respiratory compromise. The equilibration between FIO2 and PaO2 is rapid in adult horses.

Pneumoperitoneum as an uncommon complication after an axillary laceration in a horse.

Lacerations of the axillary region occur frequently in horses. Typical complications caused by entrapment of air in the wound during locomotion are subcutaneous emphysema, with consecutive pneumomediastinum and pneumothorax. In this case report, the clinical, radiographic and laboratory diagnosis and management of these complications after an axillary laceration that finally resulted in pneumoperitoneum are described. A 1-year-old Hannoveranian was presented with a pre-existing axillary laceration of unknown duration and subcutaneous emphysema in the surrounding tissue. Due to extensive tissue loss, attempts to adequately close the wound surgically and by packing with sterile dressing material were unsuccessful. Despite stall confinement and tying of the horse, subcutaneous emphysema was progressive and pneumomediastinum as well as pneumothorax was developed. These complications were monitored radiographically. On day 5 after admission, signs of air accumulation were detected on radiographs craniodorsally in the peritoneum and a pneumoperitoneum was diagnosed. Repeated thoracentesis with a teat cannula to gradually evacuate the thoracic cavity was used in combination with nasal oxygen insufflation to treat global respiratory insufficiency. Subcutaneous emphysema and all other complications resolved progressively and the horse was discharged from the hospital 21 days after admission when the axillary wound was adequately filled with granulation tissue. The wound healed fully 1 month later and the horse did not develop long-term complications within the following year. To the authors´ knowledge, the development of pneumoperitoneum including its radiographic monitoring following an axillary laceration has not been described in horses previously.

Animal Model of Video-Assisted Cecum and Ileum Instrumentation for Equine Visceral Pain Study.

This study aimed to describe an animal model for studying equine visceral pain using minimally invasive and video-assisted cecum and ileum instrumentation. The access to the cecum and ileum was affected because of a previous typhlostomy. For video-assisted distention of the cecum and ileum, a distention device, which we developed using an endotracheal Rusch probe, was used, adapted, and coupled to a cuffometer to inflate and measure the pressure of the cuff attached to its distal portion. In a video-assisted manner, the distal portion of the device was introduced into the cecum and ileum, which contained the cuff in its distal portion, properly positioning it in the lumen. The cuff of the distension device was insufflated after the measurement of baseline physiological parameters of the animals and video-assisted confirmation of its right placement in the cecum and ileum lumen (M0). Was performed in one moment through two simultaneous cuff compressions and 1 minute of animal observation to evaluate the degree of abdominal discomfort manifestations (M1). To cease these stimuli, the cuff was deflated by disconnecting the extensor of the distension device attached to its proximal portion (M2). The procedure was easily performed in most cases. Slow and progressive insufflation allowed subjective adjustment of the intensity of the pain stimulus based on behavioral manifestations. Even with a low rate of complications, the model is feasible and reproducible for studies on visceral pain and the evaluation of analgesic effects.

Ex vivo comparison of leak testing of canine jejunal enterotomies: Saline infusion versus air insufflation.

OBJECTIVE: To compare the ability to detect leakage of enterotomy closures by intraluminal injection of saline or air. STUDY DESIGN: Ex vivo study. ANIMALS: Grossly normal jejunal segments (n = 60) from five fresh canine cadavers. METHODS: Eight-centimeter jejunal segments were randomly assigned to two control (saline control [n = 5], air control [5]) and two treatment groups (injection of saline [n = 25] or air [25] after enterotomies were closed in a simple continuous pattern using 4-0 glycomer 631). Initial leak pressure (ILP, mean ± SD), maximum intraluminal pressure (MIP), and leakage location were compared. For all air insufflation constructs, the volume of air insufflated at the time of initial leakage was recorded. RESULTS: The ILPs of control segments did not differ whether injected with saline (405.71 ± 56.97 mmHg) or air (376.84 ± 42.54, p = 1.00). Enterotomy closures leaked at lower pressures when injected with air (ILP: 68.52 ± 6.56) compared to saline (87.76 ± 5.20, p = .03). Similar results were obtained when comparing MIPs. A moderate association (r = .51) was identified between volume of air infused and ILPs. The strength of the association improved when stratified by cadaver. The location of leakage-most commonly suture tracks-was identified for all air constructs and for 14 of 25 saline constructs. CONCLUSION: Enterotomy closures leaked at lower pressures after intraluminal injection of air compared to saline. CLINICAL SIGNIFICANCE: Intraoperative leak testing of small intestinal enterotomy closures may be rendered more sensitive and precise by the use of air instead of saline as the infusate.

Endometrial angiogenesis induced by uterine insufflation with an oxygen-ozone gas mixture in mares.

Ozone (O3 ) therapy has been used to improve peripheral tissue oxygenation in humans and domestic animals. The goal of the present study was to characterize histological changes in the endometria of healthy equines following tissue exposure to gas mixtures enriched with different concentrations of O3 . Cycling mares without endometrial degeneration were divided into three groups according to treatment (n = 9 mares/group). The uteri from the O3 , ½O3 and control groups were insufflated for 3 min with gas containing 42, 21 and 0 µg O3 ml-1 , respectively. Treatments were performed every three days from D0 to D6. Endometrial samples were collected immediately before the first treatment and 24 hr after the last treatment. The following nine histological parameters were evaluated: (i) the number of endometrial blood vessels, (ii) endometrial vascular degree (EVD), (iii) increase rate of blood vessels, (iv) increase rate of EVD, (v) glandular total area, (vi) glandular lumen area, (vii) intraglandular secretion area, (viii) glandular epithelial height and (ix) luminal epithelial height. In the O3 group, a positive effect from treatment (p < .01) was detected for all vascular parameters (i, ii, iii and iv), glandular total area, intraglandular secretion area and glandular epithelial height. Compared to the control group, the ½O3 group had greater (p < .01) EVD (84.1 ± 12%) and a higher increase rate of blood vessels (151.9 ± 47.1%). Uterine insufflation with low or intermediate concentrations of the O2 -O3 gas mixture induced endometrial angiogenesis. Morphometry, but not morphology, of the endometrial glands was affected by local O3 therapy. These findings would be of great significance for the development of new therapies for infertility in mares.

Cardiovascular and respiratory effects of carbon dioxide pneumoperitoneum in the domestic rabbit (Oryctolagus cuniculus).

The objective of this study was to evaluate the effect of intra-abdominal pressure (IAP) on cardiorespiratory parameters during pneumoperitoneum with carbon dioxide in domestic rabbits. Six juvenile female New Zealand white rabbits were assigned to randomized sequences of IAP (0, 4, 8 mmHg) in a crossover study. The following parameters were measured at each IAP: direct arterial blood pressure (ABP); cardiac output, (CO), cardiac index, and stroke volume index (CI, SVI); heart rate; end-tidal carbon dioxide (ETCO2); arterial blood gases (PaCO2, PaO2); peak inspiratory pressure (PIP); and peripheral oxygen saturation (SpO2). Between IAPs, the abdomen was desufflated for a 5-minute washout period. Mixed linear regression models were used for statistical analysis. Heart rate, SpO2, and ABP were not significantly affected by IAP, although there was a positive increase in ABP with IAP. Partial pressure of carbon dioxide (PaCO2) was increased at an IAP of 8 mmHg and ETCO2 and PIP were greater with each IAP applied. Cardiac output and CI were significantly decreased with IAP and, although SVI showed the same trend, it was not statistically significant. In conclusion, pneumoperitoneum with carbon dioxide causes an increase in ETCO2, PaCO2, and PIP, whereas cardiac output and CI decrease. These cardiorespiratory changes should be considered when determining the optimal IAP for laparoscopic procedures in rabbits.

L'effet de différentes pressions intra-abdominales (IAP) sur les paramètres cardiorespiratoires durant un pneumopéritoine à CO2 a été évalué sur 6 femelles lapins néo-zélandais. Les lapins furent assignés à des séquences aléatoires d'IAP (0, 4, 8 mmHg) dans une étude croisée. Les paramètres suivants furent mesurés à chaque IAP : pression artérielle directe (ABP), débit cardiaque, indice de volume systolique et cardiaque (SVI, CI), fréquence cardiaque, CO2 de fin d'expiration (ETCO2), gaz sanguins artériels (PaCO2, PaO2), pic de pression inspiratoire (PIP) et saturation en oxygène (SpO2). Entre chaque IAP, l'abdomen était dégonflé pendant une période de 5 minutes. Des modèles de régression linéaire mixte ont été utilisés pour l'analyse statistique. La fréquence cardiaque, le SpO2, et l'ABP ne furent pas affectés significativement par l'IAP, bien qu'il y eût une augmentation de l'ABP avec l'IAP. La PaCO2 était augmentée a une pression de 8 mmHg et le ETCO2 et le PIP augmentaient avec chaque pression. Le débit cardiaque et le CI étaient significativement diminués avec une augmentation de l'IAP et, bien que le SVI montraient la même tendance, ces baisses n'étaient pas statistiquement significatives. En conclusion, un pneumopéritoine avec du CO2 entraine une augmentation de la ETCO2, du PaCO2, et du PIP, alors que le débit cardiaque et la CI diminuent. Ces changements cardiorespiratoires doivent être pris en compte pendant la détermination de la pression intra-abdominale optimale à utiliser pour des chirurgies laparoscopiques chez le lapin.(Traduit par les auteurs).

Water immersion vs. air insufflation in canine duodenal endoscopy: is the future underwater?

Endoscopy represents a commonly employed technique for canine enteropathies. Different trials in human intestinal endoscopy have suggested that the introduction of water for luminal distension, in place of air, improves the visualization of the mucosal texture and decreases pain. The aim of the study was to compare water immersion (WI) vs. air insufflation (AI) during duodenoscopy in anesthetized dogs in terms of mucosal visualization and nociception. Twenty-five dogs undergoing duodenoscopy were included. The same image of the descending duodenum was recorded applying WI and AI. Each pair of images was analyzed using morphological skeletonization, an image entropy evaluation, and a subjective blind evaluation by three experienced endoscopists. To evaluate differences in nociception related to the procedure applied, heart rate and arterial blood pressure were measured before, during and after WI/AI. To compare the two methods, a t-test for paired data was applied for the image analysis, Fleiss' Kappa evaluation for the subjective evaluation and a Friedman test for anesthetic parameters. No differences were found between WI and AI using morphological skeletonization and entropy. The subjective evaluation identified the WI images as qualitatively better than the AI images, indicating substantial agreement between the operators. No differences in nociception were found. The results of the study pointed out the absence of changes in pain response between WI and AI, likely due to the sufficient control of nociception by the anesthesia. Based on subjective evaluation, but not confirmed by the image analysis, WI provided better image quality than AI.

Cardiopulmonary changes induced by retroperitoneal insufflation in healthy dogs in sternal recumbency with the abdomen unsupported.

This study assessed the effects of retroperitoneal carbon dioxide (CO2) insufflation on cardiopulmonary variables and intra-abdominal pressure (IAP) in mechanically ventilated dogs in sternal recumbency with the abdomen unsupported, following placement of a positioning kit and towels under the pectoral and pelvic regions. General anesthesia was induced in eight healthy adult male Beagles. A Swan-Ganz catheter was placed in the pulmonary artery via the jugular vein for cardiac output measurements. A Foley urethral catheter was placed to monitor transvesical IAP. A 10 mm balloon blunt-tip trocar was inserted into the retroperitoneal space. With a fixed respiratory rate and tidal volume by mechanical ventilation, insufflation pressure was sequentially increased from 0 to 10 mmHg in 5 mmHg increments, followed by desufflation. All variables were measured before insufflation, 5 min after the establishment of each insufflation pressure, and after desufflation. At 10 mmHg, the IAP was nearly equal to insufflation pressure. Cardiopulmonary function was not compromised at any point, although the cardiac index (CI), heart rate, mean arterial pressure (MAP), and mean pulmonary arterial pressure increased within normal ranges. End-tidal CO2 concentration, arterial CO2 partial pressure, and oxygen delivery index (DO2I) increased, whereas pH decreased, at 10 mmHg. CI, MAP, and DO2I did not recover to baseline after decompression. Thus, retroperitoneal CO2 insufflation up to 10 mmHg is well tolerated by mechanically ventilated dogs positioned in sternal recumbency with the abdomen unsupported, although sympathetic changes may occur with an insufflation pressure increase.

Esophageal insufflation computed tomography in clinically normal dogs.

OBJECTIVE To assess the feasibility of esophageal insufflation CT (EICT) for evaluation of the esophagus in dogs. ANIMALS 7 clinically normal adult Beagles. PROCEDURES Each dog was anesthetized twice with 1 week between anesthesia sessions. Dogs were positioned in sternal recumbency during all CT scans. During the first anesthesia session, a CT scan was performed before the esophagus was insufflated (insufflation pressure, 0 mm Hg) and unenhanced and contrast-enhanced EICT scans were performed after CO2 was insufflated into the esophageal lumen to achieve a pressure of 5 mm Hg. For the contrast-enhanced scan, each dog received iohexol (600 mg/kg, IV), and the scan was performed 30 seconds later. During the second anesthesia session, unenhanced and contrast-enhanced EICT scans were performed in the same manner except the insufflation pressure achieved was 10 mm Hg. The esophageal luminal cross-sectional area and wall thickness were measured at each of 5 segments, and mean values were compared among the 3 insufflation pressures and between unenhanced and contrast-enhanced images. RESULTS Mean esophageal luminal cross-sectional area increased and esophageal wall thickness decreased as insufflation pressure increased. Measurements did not differ significantly between unenhanced and contrast-enhanced images. The stomach became distended with CO2 at an insufflation pressure of 10 mm Hg but not at 5 mm Hg. No adverse effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested EICT was feasible for esophageal evaluation in dogs. Further research is necessary to determine the optimal insufflation pressure for the procedure and its diagnostic efficacy in diseased patients.

Cardiorespiratory effects of variable pressure thoracic insufflation in cats undergoing video-assisted thoracic surgery.

OBJECTIVE: To evaluate the effects of intrathoracic insufflation on cardiorespiratory variables and working space in cats undergoing video-assisted thoracic surgery. STUDY DESIGN: Prospective randomized study. ANIMALS: Six healthy cats. METHODS: Cats were anesthetized using a standardized protocol. A Swan-Ganz catheter was positioned in the pulmonary artery under fluoroscopic guidance for measurement of cardiac output. Intrathoracic pressures (ITP) of 0 (baseline), 3, and 5 mm Hg were induced with CO2 and maintained for 30 minutes. Statistical comparison of cardiorespiratory variables was performed. After the procedures, all cats were recovered from anesthesia. Videos of thoracic working space at each ITP level were scored in a blinded fashion by 3 board-certified surgeons using a numerical scale from 0-10. RESULTS: All cats tolerated insufflation with 3 and 5 mm Hg for 30 minutes without oxygen desaturation, although ventilatory levels had to be increased substantially to maintain eucapnia and oxygenation. Cardiac index was not significantly different from baseline after 30 minutes at 3 mm Hg but was significantly lower after 30 minutes at 5 mm Hg compared with 3 mm Hg. Oxygen delivery was unaffected by 3 or 5 mm Hg compared with baseline. Scores for working space increased between baseline and 3 and 5 mm Hg but were not different between 3 and 5 mm Hg. CONCLUSION: CO2 insufflation to 5 mm Hg seems well tolerated in healthy cats, provided ventilatory settings are substantially increased as ITP increases. CLINICAL SIGNIFICANCE: Thoracic CO2 insufflation of 3 mm Hg in cats during video-assisted thoracic surgery is associated with less hemodynamic perturbation than 5 mm Hg insufflation and may provide the benefit of improved working space compared with baseline.

Effect of pneumoperitoneum with warmed humidified or standard-temperature carbon dioxide during laparoscopy on core body temperature, cardiorespiratory and thromboelastography variables, systemic inflammation, peritoneal response, and signs of postoperative pain in healthy mature dogs.

OBJECTIVE To evaluate effects of pneumoperitoneum created with warmed humidified CO2 (WHCO2) during laparoscopy on core body temperature, cardiorespiratory and thromboelastography variables, systemic inflammation, peritoneal response, and signs of postoperative pain in healthy mature dogs. ANIMALS 6 mature purpose-bred dogs. PROCEDURES In a randomized crossover study, each dog was anesthetized twice, and pneumoperitoneum was created with standard-temperature CO2 (STCO2; 22°C and 0% relative humidity) and WHCO2 (37°C and 98% relative humidity). Data were collected during each procedure, including core body temperature, cardiorespiratory and thromboelastography variables, and inflammatory biomarkers. Peritoneal biopsy specimens were collected and evaluated with scanning electron microscopy. Dogs were assessed for signs of postoperative pain. RESULTS Mean core body temperature was significantly lower (35.2°C; 95% confidence interval, 34.5° to 35.8°C) with WHCO2 than with STCO2 (35.9°C; 95% confidence interval, 35.3° to 36.6°C) across all time points. Cardiac index increased during the procedure for both treatments but was not significantly different between treatments. Thromboelastography variables did not differ significantly between treatments as indicated by the coagulation index. Subjective evaluation of peritoneal biopsy specimens revealed mesothelial cell loss with STCO2. There was no significant difference in circulating C-reactive protein or interleukin-6 concentrations. There was a significant increase in the number of postoperative pain scores > 0 for the WHCO2 treatment versus the STCO2 treatment. CONCLUSIONS AND CLINICAL RELEVANCE Analysis of these data suggested that effects on evaluated variables attributable to the use of WHCO2 for creating pneumoperitoneum in healthy mature dogs undergoing laparoscopy did not differ from effects for the use of STCO2.

Evaluation of post-operative pain after active desufflation at completion of laparoscopy in mares undergoing ovariectomy.

The cause of transient post-operative pain in a subset of horses undergoing laparoscopy is unclear. The objective of this study was to evaluate if residual pneumoperitoneum is associated with transient post-operative pain in mares undergoing ovariectomy. Thirty-eight mares undergoing routine standing laparoscopic ovariectomy were randomly allocated into 2 groups. At the completion of laparoscopy, either the abdominal cavity was actively desufflated or the cannulas were opened to achieve ambient pressure before incisional closure. Assessments were performed for 18 hours after surgery using a validated visceral/somatic pain scale for horses. Overall, pain was minimal in both groups (median score 2/39) post-surgery. Active desufflation of the pneumoperitoneum at the completion of laparoscopy approached statistical significance (P = 0.07) in decreasing pain at 12 hours after laparoscopy. However, effects of active desuffation were not significant throughout the monitored 18-hour post-surgery period. We conclude that the decision to actively desufflate at the completion of laparoscopy should be based on surgeon's preference.

Évaluation de la douleur postopératoire après un désoufflement actif à l'achèvement d'une laparoscopie chez les juments subissant une ovariectomie. La cause d'une douleur postopératoire transitoire dans un sous-groupe de chevaux subissant une laparoscopie est indéterminée. Cette étude avait pour objectif d'évaluer si le pneumopéritoine résiduel est associé à de la douleur postopératoire chez les juments subissant une ovariectomie. Trente-huit juments subissant une ovariectomie laparascopique debout de routine ont été réparties au hasard dans deux groupes. À l'achèvement de la laparoscopie, soit la cavité abdominale a été activement désoufflée ou les canules ont été ouvertes pour obtenir une pression ambiante avant la fermeture de l'incision. Des évaluations ont été réalisées pendant 18 heures après la chirurgie en utilisant une échelle de douleur viscérale/somatique validée pour les chevaux. Dans l'ensemble, la douleur a été minimale dans les deux groupes (note médiane de 2/39) après la chirurgie. La désoufflement actif du pneumopéritoine à l'achèvement de la laparoscopie s'approchait de l'importance statistique (valeur de P = 0,07) en réduisant la douleur à 12 heures après la laparoscopie. Cependant, les effets du désoufflement actif n'étaient pas significatifs pendant la période de surveillance 18 heures après la chirurgie. La décision de désouffler activement à l'achèvement de la laparoscopie est toujours sujette à la préférence du chirurgien.(Traduit par Isabelle Vallières).

In vitro evaluation of a simulated pneumoperitoneum environment using carbon dioxide on canine transitional cell carcinoma.

OBJECTIVE: To assess the impact of a simulated CO2 pneumoperitoneum environment on the viability and proliferation of canine transitional cell carcinoma (TCC) cells in vitro. STUDY DESIGN: In vitro study. METHODS: A control Madin-Darby canine kidney (MDCK) cell line and 3 canine TCC cell lines were exposed to 100% CO2 at pressure of 0, 5, 10, or 15 mmHg for 2 hours by using an airtight chamber and a mechanical insufflator at 37°C. Culture media pH was measured. Viability and proliferation were assessed by using a resazurin assay and trypan blue dye, respectively. RESULTS: The pH in the media significantly decreased immediately after CO2 exposure but returned to normal within 1 hour. The viability of the cell lines was variably affected at the evaluated pressures. Insufflation pressure of 10 mmHg resulted in significantly decreased cell viability compared with control. The impact of 15 mmHg CO2 was comparable to 0 mmHg and control. CO2 insufflation pressure had no significant effects on proliferation up to 7 days postexposure. Conclusion/Clinical significance: A positive pressure CO2 environment significantly decreased the viability of TCC and MDCK cells under specific conditions without influencing their proliferation up to 7 days postexposure. Investigating these effects in clinical patients undergoing CO2 laparoscopy is essential to assess for port site metastasis or peritoneal carcinomatosis in order to translate these in vitro results to clinical recommendations.