Effects Of Intra-abdominal Pressure Research Articles

The Effect of Intra-abdominal Pressure on Heart Rate Variability and Hemodynamics During Laparoscopic Cholecystectomy: A Prospective Observational Study.

Introduction This study aimed to evaluate hemodynamic changes using heart rate variability (HRV) measurements in diabetic and nondiabetic patients who will undergo laparoscopic cholecystectomy and to provide our preoperative measurements to guide us for better perioperative anesthesia management. Materials and methods The study included 143 patients aged 40 years and older who would undergo elective laparoscopic surgery, did not have any comorbidities other than diabetes mellitus (DM) type II, and were in theAmerican Society of Anesthesiologists(ASA) class I-III risk group. Patients were divided into two groups: the control group (n = 77) and the DM group (n = 66). The preoperativeglycated hemoglobin (HbA1C) level was measured. Peripheral oxygen saturation (SpO2) and hemodynamic parameters such as systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR), and HRV parameters were measured preoperatively, perioperatively, and postoperatively. Intra-abdominal pressure (IAP) was administered at 10-12 mmHg. Results Even though SAP, DAP, MAP, and HR decreased with induction, they increased with insufflation, and an overall decrease was seen at the postoperative 24th hour for all parameters. When the groups were evaluated, no difference was observed except that the DAP was significantly lower in the DM group (p = 0.029) at insufflation and the HR was higher in the DM group at induction, and the difference was significant (p = 0.001). Preoperative HRV parameters were significantly lower in the DM group. According to the HRV parameters, although a decrease was observed after induction and insufflation, conversely, an increase was observed postoperatively. When the postoperative and preoperative values were compared, the standard deviation of the NN (R-R) intervals (SDNN), SDNN index, high frequency (HF), low frequency (LF), and LF/HF parameters were found to be significantly lower in the DM group than in the control group. Conclusion Diabetic patients are more sensitive to increased intra-abdominal pressure (IAP) in laparoscopic surgery, and the effects on cardiac autonomic functions can be determined by HRV measurements without clinically reflecting on hemodynamic data. Additionally, in diabetic patients with preoperative LF and/or HF values less than 100, we believe that careful follow-up in terms of autonomic neuropathy complications and anesthesia management should be done more meticulously in these patients.

Effect of intra-abdominal pressure on maximum level of intrathecal sensory block: A preliminary randomized controlled trial

Objectives: Increase in Intra-Abdominal Pressure (IAP) is commonly accepted as a cause for intrathecal dose sparing and consequently higher level of sensory block during pregnancy. There is however very little actual data evaluating the relationship. Thus, we aimed to evaluate association between IAP and maximum level of sensory block following intrathecal injection of hyperbaric bupivacaine as well as plain levobupivacaine for cesarean section. Methods: Preliminary randomized controlled blinded trial included females aged 18-40 years, scheduled for elective cesarean section under single-shot subarachnoid block. After randomization, they received either intrathecal hyperbaric bupivacaine (group H) or plain (isobaric) levobupivacaine (group P) in a dose of 12.5 mg (n = 40 each). IAP was measured before and after the spinal block, using the recommended intravesical technique. The maximum level of sensory block and the IAPs were measured in each patient. Results: There was no significant correlation of IAPprespinal with maximum level of sensory block for group H (P = 0.334; rs = -0.157) or group P (P = 0.637; rs = -0.078). Similarly, there was no significant correlation of the IAPpostspinal: group H (P = 0.370; rs = -0.145); and group P (P = 0.714; rs = -0.061). Both group H and group P had similar IAPprespinal (15.9 [14.3-18.2] and 15.3 [14.3-17.4] mmHg, respectively) (P = 0.474); as well as IAPpostspinal (15.2 [13.8-17.2] and 14.6 [13.4-16.0] mmH, g respectively) (P = 0.239). Among ancillary observations, duration of sensory block was significantly longer for group P versus group H (133.6 ± 24.2 and 103 ± 23.4 mins; P < 0.000). However, the maximum levels of sensory and motor block, respective times required to achieve them, as well as incidences of intraoperative hypotension and bradycardia were statistically similar between group H and group P (P > 0.05). Conclusions: The IAP was raised to the level of conventionally defined intra-abdominal hypertension (>12 mmHg) in patients scheduled for elective cesarean section. However, despite being increased, the IAPprespinal or IAPpostspinal did not show any significant association with the maximum level of sensory block (P > 0.05).

Effect of intraabdominal hypertension on splanchnic blood flow in children with appendicular peritonitis.

Background and Aims:Intraabdominal hypertension (IAH) is poorly diagnosed condition that cause splanchnic hypoperfusion and abdominal organs ischemia and can lead to multiple organ failure. There are no scientific data regarding effect of intraabdominal pressure (IAP) on splanchnic circulation in children.Material and Methods:Ninety-four children after surgery for appendicular peritonitis were enrolled in the study. After IAP measurement children were included in one of two groups according IAP levels: “without IAH” (n = 51) and “with IAH” (n = 43). Superior mesenteric artery (SMA) and portal vein (PV) blood flows (BFSMA, BFPV, mL/min) were measured, and SMA and PV blood flow indexes (BFISMA, BFIPV, ml/min*m2) and abdominal perfusion pressure (APP) were calculated in both groups.Results:Median BFISMA and BFIPV in group “with IAH” were lower by 54.38% (P < 0.01) and 63.11% (P < 0.01) respectively compared to group “without IAH”. There were strong significant negative correlation between IAP and BFISMA (rs = –0.66; P < 0.0001), weak significant negative correlation between IAP and BFIPV (rs = –0.36; P = 0.0001) in group “with IAH” and weak significant negative correlation between IAP and BFISMA (rs = –0.30; P = 0.0047) in group “without IAH”. There were no statistically significant correlations between IAP and BFIPV in group “without IAH”, between BFISMA and APP in both groups and between BFIPV and APP in both groups.Conclusion:Elevated IAP significantly reduces splanchnic blood flow in children with appendicular peritonitis. BFISMA and BFIPV negatively correlate with IAP in these patients. There is no correlation between BFISMA/BFIPV and APP in children with IAH due to appendicular peritonitis.

Effects of Intra-abdominal Pressure with Visual Feedback on Muscle Activation of Upper Trapezius and Sternomastoid during Forced Inspiration in Individuals with Costal Respiration

Effects of Intra-abdominal Pressure with Visual Feedback on Muscle Activation of Upper Trapezius and Sternomastoid during Forced Inspiration in Individuals with Costal Respiration

Effects of intra-abdominal pressure on laparoscopic working space in domestic rabbits (Oryctolagus cuniculus).

To assess the effects of 3 intra-abdominal pressures (IAPs) on pneumoperitoneal (laparoscopic working space) volume in domestic rabbits (Oryctolagus cuniculus). 6 female New Zealand White rabbits. A Latin-square design was used to randomly allocate sequences of 3 IAPs (4, 8, and 12 mm Hg) to each rabbit in a crossover study. Rabbits were anesthetized, subumbilical cannulae were placed, and CT scans were performed to obtain baseline measurements. Each IAP was achieved with CO2 insufflation and maintained for ≥ 15 minutes; CT scans were performed with rabbits in dorsal, left lateral oblique, and right lateral oblique recumbency. The abdomen was desufflated for 5 minutes between treatments (the 3 IAPs). Pneumoperitoneal volumes were calculated from CT measurements with 3-D medical imaging software. Mixed linear regression models evaluated effects of IAP, rabbit position, and treatment order on working space volume. Mean working space volume at an IAP of 8 mm Hg was significantly greater (a 19% increase) than that at 4 mm Hg, and was significantly greater (a 6.9% increase) at 12 mm Hg than that at 8 mm Hg. Treatment order, but not rabbit position, also had a significant effect on working space. Minor adverse effects reported in other species were observed in some rabbits. A nonlinear increase in abdominal working space was observed with increasing IAP. Depending on the type of procedure and visual access requirements, IAPs > 8 mm Hg may not provide a clinically important benefit for laparoscopy in rabbits.

A musculoskeletal model of the lumbar spine using ArtiSynth – development and validation

A musculoskeletal model of the spine was created using ArtiSynth, an open-source biomechanical modelling toolkit. The model included the entire spine and rib cage, with the lumbar vertebrae being mobile and 210 muscle fascicles. Muscle parameters needed for a full Hill-type musculotendon model including tendon ratios and pennation angles along with muscle force-length and force-velocity curves were incorporated into the model, as were the nonlinear stiffness of the functional spinal units and the effect of intra-abdominal pressure. We used forward dynamics-assisted data tracking for the estimation of muscle forces and validated the solution method by comparing the predicted spinal forces vs. the results of two in vivo experiments in the literature. Our model produced larger maximum extension moment in flexion than extension, which is observed in in vivo experiments. These results could not be achieved without the inclusion of the muscle force-length relationship. The model was also able to predict the ratios of axial forces at L4–L5 as measured in vivo intradiscal pressures for three cases of upright standing, holding a crate close to and far from the chest. Due to the high stiffness of the spine, our solution method was sensitive to input kinematics, which hindered extensive validation of the model for body positions other than standing. Modifying the solution method, possibly by only tracking the angular motion of the vertebrae rather than their translational motion, should make the model less sensitive and enable further validation.

The Effect of Intra-Abdominal Pressure on Sensory Block Level of Single-Shot Spinal Anesthesia for Cesarean Section

(Int J Obstet Anesth. 2015;24(1):35–40) There is an association between pregnancy and increased intrathecal local anesthetic spread (and thus, lower local anesthetic requirements), although the exact mechanisms behind this association are unknown. There are 2 potential anatomic explanations: (1) in the supine position, the pregnant uterus compresses the inferior vena cava (IVC), diverting blood into the vertebral venous system and displacing lumbosacral cerebrospinal fluid (CSF) in a cranial direction; or (2) in addition to direct compression of the IVC, the growing uterus during pregnancy leads to a global increase in intra-abdominal pressure (IAP).

Physiologic changes with abdominal wall reconstruction in a porcine abdominal compartment syndrome model.

Abdominal compartment syndrome (ACS) is a severe complication of ventral hernia repair. The aims of this study were to investigate the effects of intra-abdominal pressure on the physiologic changes of abdominal wall reconstruction and component separation in a porcine model. Ventral hernia repair (VHR) was simulated by abdominal fascial imbrication of a 10 × 15 cm defect in 45 Yorkshire pigs assigned to five experimental groups. ACS was simulated by a Stryker endoscopy insufflator with intra-abdominal pressure elevated to 20 mmHg in two groups. Component separation was performed in one of these groups and in one group without ACS. Physiological parameters were measured before and after the procedures and monitored for 4 h. The animals were euthanized for histologic analysis of organ damage. VHR led to an increase in intra-abdominal pressure, bladder pressure, and central venous pressure by an average of 14.89, 13.93, and 14.69 mmHg (p < 0.001) in all animals. Component separation was performed in 25 animals and the three pressures reduced by 9.11, 8.00, 7.89 mmHg (p < 0.001). ACS correlated with higher percentages of large and small bowel necrosis compared to groups without abdominal compartment syndrome. The results confirm that primary repair of large abdominal wall defects leads to increased intra-abdominal pressure, which can be reduced with component separation. In animals with ACS, component separation may reduce the risk of organ damage. Central venous pressure, bladder pressure, and other physiologic parameters accurately correlated with elevated intra-abdominal pressure and may have utility as markers for diagnosis of ACS.

The effect of intra-abdominal pressure on sensory block level of single-shot spinal anesthesia for cesarean section: an observational study

BackgroundIncreased intra-abdominal pressure in pregnancy is thought to affect intrathecal drug spread. However this assumption remains largely untested. The aim of this prospective study was to evaluate the association between intra-abdominal pressure and maximum sensory block level in parturients receiving spinal anesthesia for cesarean section. MethodsParturients having elective cesarean section with single-shot spinal anesthesia using hyperbaric bupivacaine 12.5mg were included. Intra-abdominal pressure was measured via a bladder catheter after establishing a T4 sensory block and at the end of surgery in the supine position with 10° left lateral tilt. We recorded demographic data, descriptive characteristics of pregnancy, self-reported weight gain and weight of the newborn. As secondary outcomes, we evaluated onset of sensory block, maximum sensory block, motor block, number of hypotensive episodes, fluid and ephedrine requirements, time to first analgesic request, time to one-point recovery of motor block and side effects. ResultsThe median value of the maximum sensory block level was T2 in 117 parturients. Median [interquartile range] pre-incision and postoperative intra-abdominal pressure were 13 [11–16] and 9 [6–10]mmHg respectively. No association was observed between maximum sensory block level and pre-incision intra-abdominal pressure (P=0.83). Weight was associated with pre-incision intra-abdominal pressure with an estimated odds ratio of 1.04 per kg (99.4% CI: 1.00–1.08). There was a moderate correlation between pre-incision and postoperative intra-abdominal pressure with a Spearman correlation coefficient of 0.67 (99.5% CI: 0.5–0.79). There was no association between pre-incision intra-abdominal pressure and secondary outcomes. ConclusionsIn parturients, intra-abdominal pressure was not associated with spinal block spread, block onset time, recovery or side effects.

Effects of intraabdominal pressure on mean platelet volume during laparoscopic cholecystectomy.

Intraabdominal hypertension is a common occurrence, especially in intensive care unit patients, and it has high mortality and morbidity rates. The onset is commonly insidious and the poor prognosis is attributed to the long delay in diagnosis. Unfortunately, diagnosis is often delayed until loss of function in the affected tissues has already occurred. The aim of this study was to determine the predictive value of mean platelet volume (MPV) in assessing the risk of intraabdominal hypertension. Pneumoperitoneum during elective laparoscopic cholecystectomy was used as a model for intraabdominal hypertension. The study included 103 patients who met the inclusion criteria. MPV evaluations were made at 3 distinct times during laparoscopic cholecystectomy based on the actual intraabdominal pressure. MPV values during preinsufflation, insufflation, and desufflation were 8.483 fL (range: 6.7 to 11.1), 8.901 fL (range: 6.8 to 11.9), and 8.538 fl (range: 5.8 to 10.9), respectively. A statistically significant increase in MPV values was found during high intraabdominal pressures (P < 0.001). A significant decrease in MPV values was also detected with desufflation (P < 0.001). Increasing MPV values may reflect increased intraabdominal pressures, which may have a clinical implementation in intraabdominal hypertension.

The Effects of Intra-Abdominal Hypertension on the Secretory Function of Canine Adrenal Glands

Intra-abdominal hypertension (IAH) can damage multiple organ systems, but the explicit impact on the adrenal gland is unclear. To evaluate the effects of intra-abdominal pressure (IAP) on the secretory function of the adrenal glands, we established canine models of IAH. By comparing morphology; hemodynamics; plasma cortisol, aldosterone, epinephrine, and norepinephrine concentrations; and the expression of IL-1, IL-6, and TNF-α in adrenal gland tissue from these dogs, we found that hemodynamic instability occurred after IAH and that IAH increased the plasma cortisol, aldosterone, epinephrine, and norepinephrine concentrations. Higher IAPs resulted in more significant changes, and the above indicators gradually returned to normal 2 h after decompression. Compared with the sham-operated group, IAH significantly increased IL-1, IL-6, and TNF-α levels in adrenal tissue, with larger increases in the presence of higher IAPs. However, the concentrations of these markers remained higher than those in the sham-operated group despite their decrease after 2 h of decompression. Histopathological examination revealed congestion, red blood cell exudation, and neutrophil infiltration in the adrenal glands when IAP was elevated; these conditions became more significant with more severe IAH. These results suggest that the secretion of adrenal hormones and adrenal gland inflammation are positively correlated with IAP and that abdominal decompression effectively corrects adrenal gland function.

Effect of intra-abdominal pressure on respiratory function in patients undergoing ventral hernia repair.

To determine the influence of intra-abdominal pressure (IAP) on respiratory function after surgical repair of ventral hernia and to compare two different methods of IAP measurement during the perioperative period. Thirty adult patients after elective repair of ventral hernia were enrolled into this prospective study. IAP monitoring was performed via both a balloon-tipped nasogastric probe [intragastric pressure (IGP), CiMON, Pulsion Medical Systems, Munich, Germany] and a urinary catheter [intrabladder pressure (IBP), UnoMeterAbdo-Pressure Kit, UnoMedical, Denmark] on five consecutive stages: (1) after tracheal intubation (AI); (2) after ventral hernia repair; (3) at the end of surgery; (4) during spontaneous breathing trial through the endotracheal tube; and (5) at 1 h after tracheal extubation. The patients were in the complete supine position during all study stages. The IAP (measured via both techniques) increased on average by 12% during surgery compared to AI (P < 0.02) and by 43% during spontaneous breathing through the endotracheal tube (P < 0.01). In parallel, the gradient between РаСО2 and EtCO2 [Р(а-et)CO2] rose significantly, reaching a maximum during the spontaneous breathing trial. The PаO2/FiO2 decreased by 30% one hour after tracheal extubation (P = 0.02). The dynamic compliance of respiratory system reduced intraoperatively by 15%-20% (P < 0.025). At all stages, we observed a significant correlation between IGP and IBP (r = 0.65-0.81, P < 0.01) with a mean bias varying from -0.19 mmHg (2SD 7.25 mmHg) to -1.06 mm Hg (2SD 8.04 mmHg) depending on the study stage. Taking all paired measurements together (n = 133), the median IGP was 8.0 (5.5-11.0) mmHg and the median IBP was 8.8 (5.8-13.1) mmHg. The overall r (2) value (n = 30) was 0.76 (P < 0.0001). Bland and Altman analysis showed an overall bias for the mean values per patient of 0.6 mmHg (2SD 4.2 mmHg) with percentage error of 45.6%. Looking at changes in IAP between the different study stages, we found an excellent concordance coefficient of 94.9% comparing ΔIBP and ΔIGP (n = 117). During ventral hernia repair, the IAP rise is accompanied by changes in Р(а-et)CO2 and PаO2/FiO2-ratio. Estimation of IAP via IGP or IBP demonstrated excellent concordance.

The evaluation of the effect of body positioning on intra-abdominal pressure measurement and the effect of intra-abdominal pressure at different body positioning on organ function and prognosis in critically ill patients

PurposeCurrent literatures confirmed the widespread and frequent development of both intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) among the critically ill with a significant associated risk of organ failure and increased mortality. The 2004 International ACS Consensus Conference committee proposed that intra-abdominal pressure (IAP) be measured in complete supine position; however, the supine position of intensive care unit (ICU) patients (<30° of bed increase) presented a significant risk for ventilator-associated pneumonia. Therefore, the potential contribution of head of bed (HOB) position in elevating IAP should be considered. The purpose of this study was to evaluate the effect of body positioning on IAP measurement and the effect of IAP at different body positions on organ function and prognosis in critically ill patients. Materials and MethodsA prospective cohort study to investigate the effect of different patient positioning on IAP, organ function, and prognosis was conducted on 88 patients admitted to a medical-surgical ICU. On admission, patients' epidemiological data and risk factors for IAH were studied; daily mean IAPs, abdominal perfusion pressure, filtration gradient, Acute Physiology and Chronic Health Evaluation II score, sequential organ failure assessment score, and multiple organ dysfunction scores were registered; next, conventional hemodynamic variables, intrathoracic blood volume index, global end-diastolic volume index and extravascular lung water using the pulse contour cardiac output system were recorded. Intra-abdominal pressures were recorded through a bladder catheter every 4 hours on the first day. Intra-abdominal pressure was measured with the patient HOB increases from 0° to 45°. Mean arterial pressure was recorded simultaneously, whereas abdominal perfusion pressure and filtration gradient (FG) were also calculated simultaneously. ResultsThe main results of this study were the incidence of IAH (28.4%) and ACS (2.3%) in ICU patients; the significant and independent relationship between IAP and HOB increases. Considering the absolute numbers of IAP, the HOB of 10° and 20° showed slight differences, whereas that of 30° and 45° showed clinically significant differences; HOB elevation was associated with clinically significant decreases in abdominal perfusion pressure and FG; patients with IAH were prone to the development of shock and multiple organ dysfunction syndrome and exhibited significantly lower intrathoracic blood volume index and global end-diastolic volume index and higher extravascular lung water. ConclusionsThere is a significant and independent relationship between IAP and HOB positioning in critically ill patients, with the HOB of 30° and 45° showing significant difference. Abdominal perfusion pressure and FG are significantly decreased when the patient's HOB is elevated. The potential contribution of body position in elevating IAP should be considered in critically ill patients with the risk of IAH and ACS.

Effects of intra-abdominal pressure on liver function assessed with the LiMON in critically ill patients.

Intra-abdominal pressure (IAP) and intra-abdominal hypertension (IAH) are associated with significant morbidity and mortality in critically ill patients. Our aim was to assess the effects of IAH on liver function using the noninvasive liver function monitoring system LiMON and to assess the prognostic value of IAP in critically ill patients. We conducted a retrospective analysis of critically ill patients who were treated in the intensive care unit (ICU). The IAP and indocyanine green plasma disappearance rate (ICG-PDR) measurements were made within 24 hours after admission to the ICU and repeated 12 hours later. Intra-abdominal pressure was measured via a Foley bladder catheter, and ICG elimination tests were conducted concurrently using the LiMON. We included 30 critically ill patients (17 women and 13 men aged 28-89 yr) in our analysis. Statistical analysis showed that the baseline IAP values were significantly higher among nonsurvivors than survivors (19.38 [standard deviation; SD 2.08] v. 13.07 [SD 0.99]). The twelfth-hour IAP values were higher than baseline measurements among nonsurvivors (21.50 [SD 1.96]) and lower than baseline measurements among survivors (11.71 [SD 1.54]); the difference between groups was significant (p < 0.001). The baseline ICG-PDR values were significantly lower among nonsurvivors than survivors (10.86 [SD 3.35] v. 24.51 [SD 6.78]), and the twelfth-hour ICGPDR values were decreased in all groups; the difference between groups was significant (p < 0.001). Our results suggest that measurement of ICG-PDR with the LiMON is a good predictor of the effects of IAP on liver function and, thus, can be recommended for the evaluation of critically ill patients.

Intra-abdominal pressure effects on porcine thoracic compliance in weightlessness: Implications for physiologic tolerance of laparoscopic surgery in space

Laparoscopic surgery (LS) is envisioned as an option for spaceflight, but requires intra-abdominal hypertension (IAH) to create the surgical domain. Prolonged weightlessness induces physiologic deconditioning that questions the ability of ill or injured astronauts to tolerate IAH. On earth, IAH results in marked ventilatory embarrassment. As there has been no previous study of physiologic changes related to LS in weightlessness, we studied anesthetized pigs in parabolic flight. Parabolic flight research laboratory. Five anesthetized Yorkshire pigs. Subjects were transported from an animal care facility and secured aboard an aircraft capable of generating hypergravity and weightlessness. Mechanical ventilation was performed using pressure control and positive end-expiratory pressure at 15 and 2 cm H2O, respectively; rate 12 breaths/min. Three abdominal conditions were used during LS: insufflation to produce IAH, abdominal wall retraction (AWR), and no abdominal wall manipulation (baseline). During each parabola breath by breath-tidal volumes (Vt) were recorded by a transport ventilator (HT-50 Newport Medical). Least square means (LS-means) of weight corrected Vt (milliliter per kilogram) by gravity (g) and abdominal condition were determined using a mixed effects model for repeated measures analysis. Increasing gravity (g) consistently reduced Vt (p = 0.0011) as did insufflation (p < 0.0001). In 1g, Vt (LS-mean 13.7, 95% confidence interval [CI]: 12.4-15.0) was relatively unaffected by AWR (LS-mean 12.8, 95% CI: 11.5-14.00), but markedly decreased by IAH (LS-mean 10.00, 95% CI: 8.9-11.1), an effect accentuated in hypergravity (LS-mean 8.1, 95% CI: 6.4-9.8). In weightlessness, Vt reduction during insufflation was near obviated (LS-mean 12.3, 95% CI: 10.6-14.1), and AWR regularly but inconsistently increased the Vt above 1g baseline (LS-mean 13.7, 95% CI: 11.7-15.8). Weightlessness protects against thoracic compliance changes that are inherent in IAH during induced pneumoperitoneum in gravity. The technique-related physiologic cost of performing LS in space deconditioned astronauts should be incorporated into design concepts for space surgery systems.

Effects of norepinephrine during intra-abdominal hypertension on renal blood flow in bacteremic dogs*

Intraabdominal hypertension reduces organ blood flow. Restoring abdominal perfusion pressure (APP) may restore renal blood flow, especially when sepsis is present. The effects of intra-abdominal pressure (IAP), followed by restoration of APP with norepinephrine, on renal blood flow were determined. Longitudinal study with bacteremia after nonbacteremic (control) conditions. University animal laboratory. Ten anesthetized mongrel dogs. IAP was raised to 10, 20, and 30 mm Hg, using intra-abdominal bags filled with saline. After each intervention, decompression was achieved by emptying the bag. Bacteremia was induced by injection of Escherichia coli. Cardiac output and renal blood flow were measured using surgically placed flow probes. Norepinephrine infusion was used to restore the mean arterial pressure to baseline at each IAP. A hypervolemic circulation was maintained throughout by infusing saline. Induction of bacteremia resulted in significant decreases in blood pressure, cardiac output, and renal blood flow (p < .01). Serial increases in IAP decreased cardiac output and renal blood flow both in control and bacteremic dogs (p < .001). These decreases were substantially corrected by abdominal decompression. In nonbacteremic control conditions, restoring APP back to baseline with norepinephrine did not fully restore cardiac output and renal blood flow (p < .001). However, in bacteremic conditions, norepinephrine was able to substantially restore cardiac output and renal blood flow to bacteremic baseline at all levels of IAP. In bacteremic conditions, the renal perfusion fraction returned to bacteremic baseline levels after correction of APP with norepinephrine and after decompression. Restoration of APP using norepinephrine improves renal blood flow in bacteremic animals with IAPs up to 30 mm Hg, and maintaining a therapeutic APP may preserve renal blood flow in patients with intra-abdominal hypertension who are at risk of IAP-induced renal injury but who have yet to meet accepted criteria for surgical decompression.

Recovery of Renal Function After Complete Renal Hilar Versus Artery Alone Clamping During Open and Laparoscopic Surgery

It is generally accepted that simultaneous occlusion of the renal artery and vein during warm ischemia is more damaging than occlusion of the artery alone. Pneumoperitoneum during laparoscopy may impair venous backflow, negating the benefits of clamping the artery alone. We evaluated the effect of laparoscopic vs open surgery on the recovery of renal function after clamping of the renal artery and vein, and the artery alone in a solitary kidney porcine model. Right laparoscopic nephrectomy was performed in 36 pigs. After a 12-day recovery period the animals were randomized into 3 groups, including 1) 120-minute warm ischemia with renal artery and vein occlusion, 2) 120-minute warm ischemia with artery alone occlusion and 3) control sham surgery. The groups were further subdivided into an open and a laparoscopic arm. Serum creatinine was assessed preoperatively, and on postoperative days 1, 3, 8 and 15. Artery alone clamping resulted in a significantly lower serum creatinine increase on postoperative days 1 and 3 in the open arm compared to the laparoscopic arm. Compared to open renal artery and vein clamping the increase in serum creatinine for open artery alone clamping was also significantly lower on postoperative days 1 and 3. No significant difference in postoperative serum creatinine was found between the laparoscopic artery alone, and the renal artery and vein arms at any time point. No significant serum creatinine changes were observed in the control sham surgery group compared to preoperative values at all followup time points. In this porcine model clamping of the artery alone during open surgery better protected the kidney from warm ischemia compared to renal artery and vein occlusion. This benefit was not observed during laparoscopic surgery. We speculated that the presence of pneumoperitoneum causes at least partial occlusion of the renal vein, thus, negating the benefit of renal artery clamping only.

Peritoneal pH during laparoscopy is dependent on ambient gas environment: helium and nitrous oxide do not cause peritoneal acidosis

Little is know about the effects of different insufflation gases on peritoneal pH during laparoscopy. However, these changes may influence the intracellular signalling system, resulting in altered cell growth or adhesiveness. The aim of this study was to determine the effects of carbon dioxide (CO(2)), nitrous oxide (N(2)O), and helium (He) on parietal and visceral peritoneal pH. The effect of different intraabdominal pressures on parietal and visceral peritoneal pH was also examined. We conducted both an ambient gas study and a pressure study. For the ambient gas study, 20 pigs were divided into the following four groups: (a) CO(2), (b) He, (c) N(2)O, and (d) abdominal wall lift (Lift) laparoscopy. Parietal and visceral peritoneal pH were measured at 15 min intervals for 180 min. For the pressure study, 15 pigs were divided into the following three groups: (a) CO(2), (b) He, (c) N(2)O laparoscopy. Baseline values were established for parietal and visceral peritoneal pH. Intraabdominal pressure was then increased stepwise at 1-mmHg intervals to 15 mmHg. After pressure was maintained for 15 min at each setting, parietal and visceral peritoneal pH were measured. Ambient gas environment was the major determinant of parietal peritoneal pH. Carbon dioxide caused parietal peritoneal acidosis. Helium, N(2)O, and Lift caused alkalotic parietal peritoneal pH. Intraabdominal pressure had a minor effect on parietal peritoneal pH. At higher intraabdominal pressure (12-15 vs 5-8 mmHg), CO(2) caused a slight decrease in parietal peritoneal pH, whereas N(2)O and He caused a slight increase in parietal peritoneal pH. Visceral peritoneal pH remained relatively unaffected during all studies. Parietal peritoneal pH during laparoscopy was highly dependent on the ambient gas environment. The effect of intraabdominal pressure on parietal peritoneal pH was of minor significance. Carbon dioxide caused a slight worsening of parietal peritoneal acidosis at higher intraabdominal pressure, whereas, N(2)O, He, and Lift did not cause parietal peritoneal acidosis.

Effects of intra-abdominal pressure on respiratory mechanics in healthy and injured lungs

Effects of intra-abdominal pressure on respiratory mechanics in healthy and injured lungs

Oleic acid and intra-abdominal pressure effects on lung morphology in an experimental animal model

s and Programme: European Society of Anaesthesiologists; 9th Annual Meeting with the Swedish Society of Anaesthesiology; Gothenburg, Sweden, 7-10 April 2001: Intensive Care Medicine