Mesure de la pression intra-abdominale par voie vésicale

Mechanical analysis of insertion problems and pain during colonoscopy: why highly skill-dependent colonoscopy routines are necessary in the first place... and how they may be avoided

BACKGROUND

Colonoscopy requires highly skill-dependent manoeuvres that demand a significant amount of training, and can cause considerable discomfort to patients, which increases the use of sedatives. Understanding the underlying fundamental mechanics behind insertion difficulties and pain during colonoscopy may help to simplify colonoscopy and reduce the required extent of training and reliance on sedatives.

METHODS

A literature search, anatomical studies, models of the colon and colonoscope, and bench tests were used to qualitatively analyze the fundamental mechanical causes of insertion difficulties and pain. A categorized review resulted in an overview of potential alternatives to current colonoscopes.

RESULTS

To advance a colonoscope through the colon, the colon wall, ligaments and peritoneum must be stretched, thus creating tension in the colon wall, which resists further wall deformation. This resistance forces the colonoscope to bend and follow the curves of the colon. The deformations that cause insertion difficulties and pain (necessitating the use of complex conventional manoeuvres) are the stretching of ligaments, and stretching of colon wall in the transverse and longitudinal directions, and the peritoneum.

CONCLUSIONS

Four fundamental mechanical solutions to prevent these deformations were extracted from the analysis. The current results may help in the development of new colonoscopy devices that reduce - or eliminate - the necessity of using highly skill-dependent manoeuvres, facilitate training and reduce the use of sedatives.

New valve-mechanical model of urinary tract function: the theory of biological dual valves

INTRODUCTION

Until now, peristalsis has been the only known method of urine transport. The main objective of this paper was to study urinary tract function - especially the upper urinary tract, the ureter - from a new mechanical point of view. The physical (physical dual valves) and biological basis (biological dual valves) of a new functional model is presented based on previous observations and knowledge.

METHODS

A review of the literature was performed, with special emphasis on ureter motility.

RESULTS

After analyzing the anatomy and physiology of the urinary tract, complemented by basic physical observations, the authors have developed a new valve-mechanical model of urinary tract function. A comprehensive mechanical hypothesis is also presented, integrating the role of peristalsis.

CONCLUSIONS

The authors believe that the new theory enhances previous knowledge. From a structural point of view, the urinary tract may be considered to consist of dualvalves. The dual-valve mechanism combined with peristalsis allows better explanation of the function of the upper urinary tract in particular. The main conclusion is that the flow in the urinary tract must be studied integrally within the body. This new theory does not contradict well-known and acknowledged theories, and moreover, it may help solve certain medical problems.

Abdominal compartment syndrome: A review

OBJECTIVES

The aims of this review were to summarize a) the consensus definitions of normal and pathologic intra-abdominal pressure (IAP); b) the techniques to measure IAP; c) the risk factors for intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS); d) the pathophysiology of ACS; and e) the current recommendations for management and prevention of ACS.

DATA SOURCES

PubMed was searched using the following terms: ACS, IAH, IAP, and abdominal decompression.

DATA SYNTHESIS

ACS represents the natural progression of end-organ dysfunction caused by increased IAP and develops if IAH is not recognized and treated appropriately. Although the reported incidence of ACS is relatively low in critically ill children (0.6%-4.7%) it may be under-recognized and under-reported. The diagnosis of IAH/ACS depends on a high index of suspicion and the accurate and frequent measurement of IAP in patients at risk. Mortality from ACS remains high (50%-60%) even when decompression of the abdomen is performed early, which highlights the importance of detection and treatment of elevated IAP before end-organ damage occurs.

CONCLUSIONS

A widespread awareness of the recognition and current approach to management and prevention of IAH and ACS is needed among pediatric intensivists, so outcome of these life-threatening disease processes might be improved.

Intra-abdominal pressure: the neglected variable in selecting the ventriculoperitoneal shunt for treating hydrocephalus

OBJECTIVE

In the selection of a ventriculoperitoneal cerebrospinal fluid shunt, the intra-abdominal pressure (IAP) is traditionally neglected as a result of the idea that its value is close to 0 mmHg. Our aim was to explore the relationship between body mass index (BMI) and IAP with the goal of providing clinically relevant data that could help neurosurgeons to estimate IAP and select the appropriate shunt for patients with hydrocephalus and especially those with normal-pressure hydrocephalus syndrome.

METHODS

Sixty patients requiring the placement of a ventriculoperitoneal shunt were included in the study. We determined weight, BMI, and IAP. IAP was measured through an intraperitoneal catheter during the shunt surgery. To determine whether a linear relationship existed between quantitative variables, linear regression analysis was used.

RESULTS

BMI was 28.1 +/- 4.8 kg/m2. Eighteen patients (30%) had normal weight, 21 (35%) were moderately overweight, and 21 (35%) were obese. IAP was related to patient BMI. A significant positive linear correlation was identified between BMI and IAP (r = 0.52; P = 0.018) with a slope of 0.31 (P < 0.001) and an intercept of -5.5.

CONCLUSION

In our study, we determined that IAP had a strong positive linear relationship with BMI. This correlation was independent of sex. An IAP of 0 mmHg can, therefore, only be assumed for patients with a normal BMI who are recumbent. In obese or overweight patients, neurosurgeons should take IAP into account when selecting both the most adequate differential pressure valve to be implanted and in which distal cavity to place the distal catheter to avoid shunt underdrainage induced by high IAP.

Abdominal compartment syndrome

Compartment syndrome is a pathophysiological term, comprising a variety of tissues and organ alterations, due to a higher than normal pressure in an anatomically detached space (compartment). In the human body, areas denoted as compartments include the orbital globe, the sub and epidural space, the abdomen, pleura, pericardium, and others. Compartment syndrome was described initially in limbs. Abdominal compartment syndrome is defined as an intra-abdominal pressure above 20 mmHg with evidence of organ failure. Abdominal compartment syndrome develops when the intra-abdominal pressure rapidly reaches certain pathological values, within several hours (intra-abdominal hypertension is observed), and lasts for 6 or more hours. The key to recognizing abdominal compartment syndrome is the demonstration of elevated intra-abdominal pressure which is performed most often via the urinary bladder, and it is considered to be the "gold standard." Multiorgan failure includes damage to the cardiac, pulmonary, renal, neurological, gastrointestinal, abdominal wall, and ophthalmic systems. The gut is the most sensitive to intra-abdominal hypertension, and it develops evidence of end-organ damage before alterations are observed in other systems. The surgical decompression of the abdomen remains the treatment of choice of abdominal compartment syndrome; this usually improves the organ changes, and is followed by one of the temporary abdominal closure techniques in order to prevent secondary intra-abdominal hypertension.