The Correlation of Intraabdominal Pressure With Renal Resistive Index.

BACKGROUND: To evaluate the correlation between intraabdominal pressure (IAP) measured via the bladder and renal resistive index (RRI) measured by Doppler ultrasonography (USG). METHODS: Eighty consecutive surgical patients were included into this study. Before Doppler USG evaluation, IAP was measured by a Foley catheter via the bladder. The left and right RRI, the diameters of the inferior vena cava and portal vein were measured by colored Doppler USG. Spearman correlation analysis was used to evaluate the correlation between different measurements. Intraabdominal hypertension (IAH) was defined as of IAP ≥ 12 mmHg. Significantly different variables from the univariate analysis between patients with and without IAH were entered into backward stepwise binary logistic regression analysis of IAH as the dependent variable. P values < 0.05 were accepted as statistically significant. RESULTS: In total, 80 patients were included into study. In 27 patients (34%) IAP was normal and in 53 patients (66%) IAH was diagnosed. The Spearman correlation analysis of IAP and the ultrasonographic measurements revealed a strong correlation between RRI and IAP (P < 0.001). Patients with IAH were more likely to be diabetic and had abdominal incisional hernia compared with patients with normal IAP (P < 0.05). The results of the multivariate logistic regression analysis revealed right RRI as the only independent predictor of IAH (B: 57.04, S. E.: 13.7, P < 0.001). CONCLUSIONS: There is a strong correlation between IAP and RRI. RRI can be an alternative, noninvasive technique for the diagnosis and follow-up of IAH after further evaluations in different patient groups.

A Clinician's Guide to Management of Intra-abdominal Hypertension and Abdominal Compartment Syndrome in Critically Ill Patients.

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Intravesical monitoring of intra-abdominal pressure after renal transplantation in children: A safety and feasibility study.

IAH after RTX can threaten graft viability. This study aimed to assess the feasibility and safety of longitudinal IAP measurements as an IAH screening method in children after RTX. A cohort of eight children with a mean ± SD [range] age 9.6 ± 6.2 [2-17] years who underwent RTX and 18 control patients were evaluated between May 2017 and February 2018. We compared longitudinal IAP measurements using a Foley manometer to other clinical monitoring data. In total, 29 IAP measurements were performed in RTX patients and 121 in controls. The mean post-operative IAP was 7.4 ± 4.3 [1-16] mm Hg following RTX and 8.1 ± 3.7 [1-19] mm Hg in controls. We noted IAH in 9 (31%) of 29 IAP measurements after RTX and in 41 (34%) of 121 IAP measurements in controls. No graft dysfunction occurred in RTX patients despite elevated IAP values. The mean ± SD [range] time expenditure for IAP measurement was 2.1 ± 0.4 [0.6-3.2] minutes. No severe complications occurred during the IAP measurements. Analysis of longitudinal IAP measurements demonstrated that IAP measurement is safe and feasible in children recovering from renal transplantation in the PICU.

Intra-abdominal pressure may be elevated in patients with open abdomen after emergent laparotomy.

PURPOSE: To estimate the change in intra-abdominal pressure (IAP) among critically ill patient who were left with open abdomen and temporary abdominal closure after laparotomy, during the first 48 h after admission. METHODS: A cohort study in a single ICU in a tertiary care hospital. All adult patients admitted to the ICU after emergent laparotomy for acute abdomen or trauma, who were left with temporary abdominal closure (TAC), were included. Patients were followed up to 48 h. IAP was routinely measured at 0, 6, 12, 24, and 48 h after admission to ICU. RESULTS: Thirty-nine patients were included, 34 were operated due to acute abdomen and 5 due to abdominal trauma. Seventeen patients were treated with skin closure, 13 with Bogota bag, and 9 with negative pressure wound therapy (NPWT). Eleven patients (28.2%) had IAP of 15 mmHg or above at time 0, (mean pressure 19.0 ± 3.0 mmHg), and it dropped to 12 ± 4 mmHg within 48 h (p < 0.01). Reduction in lactate level (2.4 ± 1.0 to 1.2 ± 0.2 mmol/L, p < 0.01) and increase in PaO2/FiO2 ratio (163 ± 34 to 231 ± 83, p = 0.03) were observed as well after 48 h. CONCLUSIONS: This is the first large report of IAP in open abdomen. Elevated IAP may be measured in open abdomen and may subsequently relieve after 48 h.

Intra-Abdominal Hypertension Is Responsible for False Negatives to the Passive Leg Raising Test.

OBJECTIVES: To compare the passive leg raising test ability to predict fluid responsiveness in patients with and without intra-abdominal hypertension. DESIGN: Observational study. SETTING: Medical ICU. PATIENTS: Mechanically ventilated patients monitored with a PiCCO2 device (Pulsion Medical Systems, Feldkirchen, Germany) in whom fluid expansion was planned, with (intra-abdominal hypertension+) and without (intra-abdominal hypertension-) intra-abdominal hypertension, defined by an intra-abdominal pressure greater than or equal to 12 mm Hg (bladder pressure). INTERVENTIONS: We measured the changes in cardiac index during passive leg raising and after volume expansion. The passive leg raising test was defined as positive if it increased cardiac index greater than or equal to 10%. Fluid responsiveness was defined by a fluid-induced increase in cardiac index greater than or equal to 15%. MEASUREMENTS AND MAIN RESULTS: We included 60 patients, 30 without intra-abdominal hypertension (15 fluid responders and 15 fluid nonresponders) and 30 with intra-abdominal hypertension (21 fluid responders and nine fluid nonresponders). The intra-abdominal pressure at baseline was 4 ± 3 mm Hg in intra-abdominal hypertension- and 20 ± 6 mm Hg in intra-abdominal hypertension+ patients (p < 0.01). In intra-abdominal hypertension- patients with fluid responsiveness, cardiac index increased by 25% ± 19% during passive leg raising and by 35% ± 14% after volume expansion. The passive leg raising test was positive in 14 patients. The passive leg raising test was negative in all intra-abdominal hypertension- patients without fluid responsiveness. In intra-abdominal hypertension+ patients with fluid responsiveness, cardiac index increased by 10% ± 14% during passive leg raising (p = 0.01 vs intra-abdominal hypertension- patients) and by 32% ± 18% during volume expansion (p = 0.72 vs intra-abdominal hypertension- patients). Among these patients, the passive leg raising test was negative in 15 patients (false negatives) and positive in six patients (true positives). Among the nine intra-abdominal hypertension+ patients without fluid responsiveness, the passive leg raising test was negative in all but one patient. The area under the receiver operating characteristic curve of the passive leg raising test for detecting fluid responsiveness was 0.98 ± 0.02 (p < 0.001 vs 0.5) in intra-abdominal hypertension- patients and 0.60 ± 0.11 in intra-abdominal hypertension+ patients (p = 0.37 vs 0.5). CONCLUSIONS: Intra-abdominal hypertension is responsible for some false negatives to the passive leg raising test.

Incidence, Risk Factors, and Outcomes of Intra-Abdominal Hypertension in Critically Ill Patients-A Prospective Multicenter Study (IROI Study).

OBJECTIVES: To identify the prevalence, risk factors, and outcomes of intra-abdominal hypertension in a mixed multicenter ICU population. DESIGN: Prospective observational study. SETTING: Fifteen ICUs worldwide. PATIENTS: Consecutive adult ICU patients with a bladder catheter. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Four hundred ninety-one patients were included. Intra-abdominal pressure was measured a minimum of every 8 hours. Subjects with a mean intra-abdominal pressure equal to or greater than 12 mm Hg were defined as having intra-abdominal hypertension. Intra-abdominal hypertension was present in 34.0% of the patients on the day of ICU admission (159/467) and in 48.9% of the patients (240/491) during the observation period. The severity of intra-abdominal hypertension was as follows: grade I, 47.5%; grade II, 36.6%; grade III, 11.7%; and grade IV, 4.2%. The severity of intra-abdominal hypertension during the first 2 weeks of the ICU stay was identified as an independent predictor of 28- and 90-day mortality, whereas the presence of intra-abdominal hypertension on the day of ICU admission did not predict mortality. Body mass index, Acute Physiology and Chronic Health Evaluation II score greater than or equal to 18, presence of abdominal distension, absence of bowel sounds, and positive end-expiratory pressure greater than or equal to 7 cm H2O were independently associated with the development of intra-abdominal hypertension at any time during the observation period. In subjects without intra-abdominal hypertension on day 1, body mass index combined with daily positive fluid balance and positive end-expiratory pressure greater than or equal to 7 cm H2O (as documented on the day before intra-abdominal hypertension occurred) were associated with the development of intra-abdominal hypertension during the first week in the ICU. CONCLUSIONS: In our mixed ICU patient cohort, intra-abdominal hypertension occurred in almost half of all subjects and was twice as prevalent in mechanically ventilated patients as in spontaneously breathing patients. Presence and severity of intra-abdominal hypertension during the observation period significantly and independently increased 28- and 90-day mortality. Five admission day variables were independently associated with the presence or development of intra-abdominal hypertension. Positive fluid balance was associated with the development of intra-abdominal hypertension after day 1.

A multifaceted individualized pneumoperitoneum strategy for laparoscopic colorectal surgery: a multicenter observational feasibility study.

BACKGROUND: While guidelines for laparoscopic abdominal surgery advise using the lowest possible intra-abdominal pressure, commonly a standard pressure is used. We evaluated the feasibility of a predefined multifaceted individualized pneumoperitoneum strategy aiming at the lowest possible intra-abdominal pressure during laparoscopic colorectal surgery. METHODS: Multicenter prospective study in patients scheduled for laparoscopic colorectal surgery. The strategy consisted of ventilation with low tidal volume, a modified lithotomy position, deep neuromuscular blockade, pre-stretching of the abdominal wall, and individualized intra-abdominal pressure titration; the effect was blindly evaluated by the surgeon. The primary endpoint was the proportion of surgical procedures completed at each individualized intra-abdominal pressure level. Secondary endpoints were the respiratory system driving pressure, and the estimated volume of insufflated CO2 gas needed to perform the surgical procedure. RESULTS: Ninety-two patients were enrolled in the study. Fourteen cases were converted to open surgery for reasons not related to the strategy. The intervention was feasible in all patients and well-accepted by all surgeons. In 61 out of 78 patients (78%), surgery was performed and completed at the lowest possible IAP, 8 mmHg. In 17 patients, IAP was raised up to 12 mmHg. The relationship between IAP and driving pressure was almost linear. The mean estimated intra-abdominal CO2 volume at which surgery was performed was 3.2 L. CONCLUSION: A multifaceted individualized pneumoperitoneum strategy during laparoscopic colorectal surgery was feasible and resulted in an adequate working space in most patients at lower intra-abdominal pressure and lower respiratory driving pressure. ClinicalTrials.gov (Trial Identifier: NCT03000465).

Management of peripartum intra-abdominal hypertension and abdominal compartment syndrome.

Normal pregnancy leads to a state of chronically increased intra-abdominal pressure. Obstetric and non-obstetric conditions may increase intra-abdominal pressure further, causing intra-abdominal hypertension and abdominal compartment syndrome, which leads to maternal organ dysfunction and a compromised fetal state. Limited medical literature exists to guide treatment of pregnant women with these conditions. In this state-of-the-art review, we propose a diagnostic and treatment algorithm for the management of peripartum intra-abdominal hypertension and abdominal compartment syndrome, informed by newly available studies.

Difference in Visceral Adipose Tissue in Pregnancy and Postpartum and Related Changes in Maternal Insulin Resistance.

OBJECTIVE: To measure the difference between first-trimester and postpartum visceral adipose tissue (VAT), the agreement of this difference with change in body mass index, and whether a difference in VAT is associated with insulin resistance or glucose mishandling. METHODS: Prospective study of 93 women with singleton pregnancies without a history of diabetes. Visceral adipose tissue depth was sonographically assessed at 11 to 14 weeks and at 6 to 12 weeks postpartum. Metabolic measures, sampled at 24 to 28 weeks and 6 to 12 weeks postpartum, included homeostatic model assessment of insulin resistance, insulin sensitivity index composite, and area under the 75-g oral glucose tolerance test curve. RESULTS: First-trimester VAT depth explained only 37% (95% confidence interval [CI], 22-52) of the variation in postpartum VAT depth. There was limited agreement between the net change in postpartum minus first-trimester VAT depth and that same net change for body mass index (Cohen's kappa, 0.26; 95% CI, 0.05-0.47). Those with a net gain in VAT depth demonstrated poorer insulin sensitivity index postpartum than women with a net regression in VAT depth-a difference of -2.0 (95% CI, -3.3 to -0.69). CONCLUSION: Sonographic assessment of postpartum VAT is feasible and may provide insight to metabolic changes between pregnancy and postpartum, beyond body mass index.

Reducing intra-abdominal pressure in peritoneal dialysis patients to avoid transient hemodialysis.

Patients treated with peritoneal dialysis (PD) are often required to switch to hemodialysis (HD) temporarily when they develop abdominal wall hernias and dialysate leaks, peritonitis or undergo thoracic or abdominal surgeries. There are significant risks associated with incident hemodialysis including possible central venous catheter infections, thrombosis, and need for invasive procedures. Therefore, strategies to avoid temporary transfer to hemodialysis are desirable. The increased intra-abdominal pressure associated with PD is largely responsible for the issues requiring withholding PD. However, the high intra-abdominal pressure, due to dialysate and body position, can be minimized by making changes to the peritoneal dialysis prescription. The lower intra-abdominal pressure may allow dialysate leaks, hernia repairs, and abdominal incisions time to heal as well as to facilitate earlier resumption of PD after catheter replacement. These strategies help to decrease morbidity and minimize cost to the health care system associated with modality switches and its complications.

Lower intra-abdominal pressure has no cardiopulmonary benefits during laparoscopic colorectal surgery: a double-blind, randomized controlled trial.

BACKGROUND: Higher intra-abdominal pressure may impair cardiopulmonary functions during laparoscopic surgery. While 12-15 mmHg is generally recommended as a standard pressure, the benefits of lower intra-abdominal pressure are unclear. We thus studied whether the low intra-abdominal pressure compared with the standard pressure improves cardiopulmonary dynamics during laparoscopic surgery. METHODS: Patients were randomized according to the intra-abdominal pressure and neuromuscular blocking levels during laparoscopic colorectal surgery: low pressure (8 mmHg) with deep-block (post-tetanic count 1-2), standard pressure (12 mmHg) with deep-block, and standard pressure with moderate-block (train-of-four count 1-2) groups. During the laparoscopic procedure, we recorded cardiopulmonary variables including cardiac index, pulmonary compliance, and surgical conditions. We also assessed postoperative pain intensity and recovery time of bowel movement. The primary outcome was the cardiac index 30 min after onset of laparoscopy. RESULTS: Patients were included in the low pressure with deep-block (n = 44), standard pressure with deep-block (n = 44), and standard pressure with moderate-block (n = 43) groups. The mean (SD) of cardiac index 30 min after laparoscopy was 2.7 (0.7), 2.7 (0.9), and 2.6 (1.0) L min-1 m-2 in each group (P = 0.715). The pulmonary compliance was higher but the surgical condition was poorer in the low intra-abdominal pressure than the standard pressure (both P < 0.001). Other variables were comparable between groups. CONCLUSION: We observed few cardiopulmonary benefits but poor surgical conditions in the low intra-abdominal pressure during laparoscopy. Considering cardiopulmonary dynamics and surgical conditions, the standard intra-abdominal pressure may be preferable to the low pressure for laparoscopic surgery.

Submaximal pelvic floor muscle contractions: similar bladder-neck elevation, longer duration, less intra-abdominal pressure.

INTRODUCTION AND HYPOTHESIS: An adequate pelvic floor muscle contraction (PFMC) elevates the bladder neck (BN) and stabilizes it during increased intra-abdominal pressure (IAP). A maximal PFMC may increase the IAP and thereby prevent BN elevation. The aim of this study was to assess BN elevation during submaximal and maximal PFMC and their achievable duration. METHODS: We recruited 68 women with stress urinary incontinence and 14 vaginally nulliparous continent controls who were able to perform a PFMC on vaginal palpation. Women were upright and performed a maximal PFMC as long as possible, followed by a submaximal PFMC, controlled by vaginal electromyogram (EMG). BN position was measured with perineal ultrasound, IAP and urethral pressure with a microtip catheter, and breathing with a circular thorax sensor. RESULTS: A submaximal PFMC elevated the bladder neck 4 mm in continent and incontinent women (p = 0.655) and 4.5 vs. 5 mm during maximal PFMC (0.528). Submaximal PFMC was maintained significantly longer than a maximal PFMC (33 vs 12 s) with no difference between groups. A maximal PFMC resulted in BN descent in 29% of continent and 28% of incontinent women, which was not observed during submaximal PFMC. Breathing was normal in 70% of continent and 71% of incontinent women during submaximal PFMC but stopped completely in 21 and 50%, respectively, during maximal PFMC (p = 0.011). IAP increase was significantly greater with maximal PFMC in both groups (24 vs. 9.6 cmH2O and 17 vs. 9 cmH2O, respectively). CONCLUSION: Submaximal PFMC are sufficient to elevate the bladder neck, can be maintained longer, and breathing was not influenced.

[Comparative diagnostic value of various methods of intracavitary pressure measurement in abdominal compartment syndrome]. / Sravnitel'naia diagnosticheskaia tsennost' metodov opredeleniia vnutripolostnogo davleniia pri abdominal'nom kompartment-sindrome.

AIM: To investigate diagnostic value of various methods of biophysical somatic parameters (BSP) monitoring in peritonitis complicated by abdominal compartment syndrome. MATERIAL AND METHODS: 220 patients with advanced peritonitis complicated by compartment syndrome were enrolled. Sensitivity, specificity, diagnostic value of the measurement of intraabdominal, intraintestinal, intrathoracic pressure, paravulnar tissues tension depending on abdominal hypertension severity were determined. RESULTS: BSP control including intraabdominal, intraintestinal, intrathoracic pressure and paravulnar tissues tension is effective for BPS disturbances diagnosis and abele to detect them significantly more often (p=0.037) compared with M. Cheatham's method alone.

Predicting Factors for Failure of Percutaneous Drainage of Postoperative Intra-Abdominal Collection.

Objective: To determine the predictive factors for failure of percutaneous drainage (PD) of postoperative intra-abdominal collection, to better select the patients who might benefit from PD. Material and Method: From September 2011 to February 2013, the authors reviewed 42 patients with symptomatic postoperative intra-abdominal collection who had received PD at Ramathibodi Hospital. The PD was considered as failure when clinical sepsis persisted or subsequent surgery was needed. Univariate analysis was used to examine the relationships between failure of PD and the collection and drainage-related variables. Results: The success rate of PD in the present study was 80%. No major complication was detected. The overall mortality was 12%. Univariate analysis showed that the presence of biliary fistula (p = 0.012), subhepatic location (p = 0.040) and the drainage catheter size of 12F (p = 0.002) were significant predictive variables for failure of PD. Conclusion: Image-guided PD of postoperative intra-abdominal collection was found to be a safe and effective procedure with few complications. Initial recognition of biliary fistula in the collection at subhepatic region or in patients underwent hepatobiliary surgery was the important prognostic factor for unsuccessful PD. These patients may be more beneficial for initial surgical drainage.

Increased pressure within the abdominal compartment: intra-abdominal hypertension and the abdominal compartment syndrome.

PURPOSE OF REVIEW: This article reviews recent developments related to intra-abdominal hypertension (IAH)/abdominal compartment syndrome (ACS) and clinical practice guidelines published in 2013. RECENT FINDINGS: IAH/ACS often develops because of the acute intestinal distress syndrome. Although the incidence of postinjury ACS is decreasing, IAH remains common and associated with significant morbidity and mortality among critically ill/injured patients. Many risk factors for IAH include those findings suggested to be indications for use of damage control surgery in trauma patients. Medical management strategies for IAH/ACS include sedation/analgesia, neuromuscular blocking and prokinetic agents, enteral decompression tubes, interventions that decrease fluid balance, and percutaneous catheter drainage. IAH/ACS may be prevented in patients undergoing laparotomy by leaving the abdomen open where appropriate. If ACS cannot be prevented with medical or surgical management strategies or treated with percutaneous catheter drainage, guidelines recommend urgent decompressive laparotomy. Use of negative pressure peritoneal therapy for temporary closure of the open abdomen may improve the systemic inflammatory response and patient-important outcomes. SUMMARY: In the last 15 years, investigators have better clarified the pathogenesis, epidemiology, diagnosis, and appropriate prevention of IAH/ACS. Subsequent study should be aimed at understanding which treatments effectively lower intra-abdominal pressure and whether these treatments ultimately affect patient-important outcomes.

The neglected role of abdominal compliance in organ-organ interactions.

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Relationship between ventral hernia defect area and intra-abdominal pressure: dynamic in vivo measurement.

BACKGROUND: It is an acceptable concept that the ventral hernia defect area will increase with a rise in intra-abdominal pressure (IAP). The literature lacks the evidence about how much this increase is in vivo. The aim of this study was to objectively measure the change in the ventral hernia defect area with increasing intra-abdominal pressure. METHODS: In a prospective study of laparoscopic ventral hernia repair, the area of hernia defect was measured from inside the abdomen using a sterile paper ruler. The horizontal (width) and vertical (length) measurements of the defect were taken at two pressure points: (IAP = 8 mmHg) and (IAP = 15 mmHg). The hernia defect area was calculated as an oval shape using a standard formula. RESULTS: Eighteen consecutive patients with a ventral hernia were included in this study (8 males: 10 females). Median age was 60 years (30-81), body mass index (BMI) was 29.9 (22.6-37.6). Changing the IAP significantly, (P < 0.001) changed the values of horizontal and vertical measurements, and the calculated area of the ventral hernia defect. The median calculated defect area, as an oval shape, was 5.6 cm(2) (Q1-Q3 = 3.5-15.5) and 6.9 cm(2) (Q1-Q3 = 4.5-18.7) at 8 and 15 mmHg IAP, respectively. The calculated area of mesh required to cover the defect with a 5 cm overlap increased by a median of 5% (Q1-Q3 = 3-6%). The change in defect area did not differ significantly between obese and non-obese patients (P = 0.5). CONCLUSIONS: Dynamic, rather than static, measurements of ventral hernia area during laparoscopy provide a simple way of in vivo objective measurement that helps the surgeon choose the appropriate area of mesh. When choosing mesh area, we support the trend toward a larger overlap of at least 5 cm if less precise methods of measuring defect area are been used.

Intra-operative wound irrigation to reduce surgical site infections after abdominal surgery: a systematic review and meta-analysis.

PURPOSE: Surgical site infection (SSI) remains to be one of the most frequent infectious complications following abdominal surgery. Prophylactic intra-operative wound irrigation (IOWI) before skin closure has been proposed to reduce bacterial wound contamination and the risk of SSI. However, current recommendations on its use are conflicting especially concerning antibiotic and antiseptic solutions because of their potential tissue toxicity and enhancement of bacterial drug resistances. METHODS: To analyze the existing evidence for the effect of IOWI with topical antibiotics, povidone-iodine (PVP-I) solutions or saline on the incidence of SSI following open abdominal surgery, a systematic review and meta-analysis of randomized controlled trials (RCTs) was carried out according to the recommendations of the Cochrane Collaboration. RESULTS: Forty-one RCTs reporting primary data of over 9000 patients were analyzed. Meta-analysis on the effect of IOWI with any solution compared to no irrigation revealed a significant benefit in the reduction of SSI rates (OR = 0.54, 95 % confidence Interval (CI) [0.42; 0.69], p < 0.0001). Subgroup analyses showed that this effect was strongest in colorectal surgery and that IOWI with antibiotic solutions had a stronger effect than irrigation with PVP-I or saline. However, all of the included trials were at considerable risk of bias according to the quality assessment. CONCLUSION: These results suggest that IOWI before skin closure represents a pragmatic and economical approach to reduce postoperative SSI after abdominal surgery and that antibiotic solutions seem to be more effective than PVP-I solutions or simple saline, and it might be worth to re-evaluate their use for specific indications.

Subperitoneal extension of disease processes between the chest, abdomen, and the pelvis.

The subserous space is a large, anatomically continuous potential space that interconnects the chest, abdomen, and pelvis. The subserous space is formed from areolar and adipose tissue, and contains branches of the vascular, lymphatic, and nervous systems. As such, it provides one large continuous space in which many disease processes can spread between the chest, abdomen, and the pelvis.

Optimizing working space in laparoscopy: CT measurement of the effect of pre-stretching of the abdominal wall in a porcine model.

BACKGROUND: Determinants of working space in minimal access surgery have not been well studied. Using computed tomography (CT) to measure volumes and linear dimensions, we are studying the effect of a number of determinants of CO2 working space in a porcine laparoscopy model. Here we report the effects of pre-stretching of the abdominal wall. METHODS: Earlier we had noted an increase in CO2 pneumoperitoneum volume at repeat insufflation with an intra-abdominal pressure (IAP) of 5 mmHg after previous stepwise insufflation up to an IAP of 15 mmHg. We reviewed the data of this serendipity group; data of 16 pigs were available. In a new group of eight pigs, we also explored this effect at repeat IAPs of 10 and 15 mmHg. Volumes and linear dimensions of the CO2 pneumoperitoneum were measured on reconstructed CT images and compared between the initial and repeat insufflation runs. RESULTS: Previous stepwise insufflation of the abdomen with CO2 up to 15 mmHg significantly (p < 0.01) increased subsequent working-space volume at a repeat IAP of 5 mmHg by 21 %, 7 % at a repeat IAP of 10 mmHg and 3 % at a repeat IAP of 15 mmHg. The external anteroposterior diameter significantly (p < 0.01) increased by 0.5 cm (14 %) at repeat 5 mmHg. Other linear dimensions showed a much smaller change. There was no statistically significant correlation between the duration of the insufflation run and the volume increase after pre-stretching at all IAP levels. CONCLUSIONS: Pre-stretching of the abdominal wall allows for the same surgical-field exposure at lower IAPs, reducing the negative effects of prolonged high-pressure CO2 pneumoperitoneum on the cardiorespiratory system and microcirculation. Pre-stretching has important scientific consequences in studies addressing ways of increasing working space in that its effect may confound the possible effects of other interventions aimed at increasing working space.