Semicontinuous intra-abdominal pressure measurement using an intragastric Compliance catheter

Objective To compare intra-abdominal pressure (IAP) measurements obtained from an intragastric Compliance catheter with the pressure measured directly in the abdominal cavity. Design and setting Prospective cohort study in an operating room of the Ghent University Hospital Patients Seven patients undergoing elective laparoscopic cholecystectomy. Interventions IAP was obtained from both an intragastric catheter and directly from the peritoneal cavity at 1-minute intervals in patients undergoing elective cholecystectomy and compared using Bland-Altman analysis. Measurements and results In 156 paired measurements obtained from 7 patients the mean difference between IAP_gastric and IAP_ref was 0.12 ±  0.70 mmHg (95% CI 0.01–0.23). Conclusions IAP measured using an intragastric Compliance catheter reliably reflects the reference IAP in patients undergoing laparoscopic cholecystectomy. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. J.J. De Waele is supported by a Clinical Doctoral Grant of the Fund for Scientific Research-Flanders (Belgium; F.W.O.-Vlaanderen).     

Pulse pressure vs. total arterial compliance as a marker of arterial health

BACKGROUND: Brachial pulse pressure (BPP) is a predictor of outcome in epidemiologic studies, but brachial and aortic pulse pressure (AoPP) may not correspond and both are influenced by multiple parameters including arterial properties and cardiac output. We sought to what extent pulse pressure (PP) measurements reflected direct measurement of arterial properties, assessed as total arterial compliance (TAC). METHODS: We studied 123 patients (76 men; age 55 +/- 11); 31 normal controls, 46 patients with coronary artery disease and 46 patients with hypertension. PP was determined from brachial cuff pressure and TAC was measured by simultaneous radial applanation tonometry and pulsed wave Doppler of the LV outflow. AoPP was calculated using a transfer function from the radial waveform. RESULTS: There was a significant difference between BPP and AoPP (57 +/- 16 vs. 45 +/- 14; P < 0.0001), although TAC correlated with BPP (r = -0.72; P = 0.01) and AoPP (r = -0.66; P = 0.01). In a multiple linear regression, the difference between BPP and AoPP was predicted by cardiac output (CO) (P = 0.002) and gender (P = 0.03). Bland-Altman analysis showed the best correspondence between BPP and AoPP in the middle tertile (CO 4.7 to 5.7 L min(-1)) with less correlation in the low and high tertiles. The same analysis by gender showed a higher difference in women than men (14 +/- 6 vs. 10 +/- 5; P < 0.0001). The difference between BPP and AoPP showed the best correlation in the control group and the worst in the hypertension group. CONCLUSION: BPP correlates with TAC in men with normal cardiac function. However, in women, in patients at the low and high extremes of function, and in patients with preclinical and overt cardiovascular disease, there appears to be incremental value in measuring TAC.     

The assumed problem of air bubbles in the tubing during intra-abdominal pressure measurement

Intensive Care Medicine -     

Influence of body position,PEEP and intra-abdominal pressure on the catheter positioning for neurally adjusted ventilatory assist

Purpose  

Neurally adjusted ventilatory assist (NAVA) relies on the patient’s electrical activity of the diaphragm (EAdi) for actuating the ventilator. Thus a reliable positioning of the oesophageal EAdi catheter is mandatory. We aimed to evaluate the effects of body position (BP), positive end-expiratory pressure (PEEP) and intra-abdominal pressure (IAP) on catheter positioning.     

Matching positive end-expiratory pressure to intra-abdominal pressure improves oxygenation in a porcine sick lung model of intra-abdominal hypertension

Introduction

Intra-abdominal hypertension (IAH) causes atelectasis, reduces lung volumes and increases respiratory system elastance. Positive end-expiratory pressure (PEEP) in the setting of IAH and healthy lungs improves lung volumes but not oxygenation. However, critically ill patients with IAH often suffer from acute lung injury (ALI). This study, therefore, examined the respiratory and cardiac effects of positive end-expiratory pressure in an animal model of IAH, with sick lungs.

Methods

Nine pigs were anesthetized and ventilated (48 +/- 6 kg). Lung injury was induced with oleic acid. Three levels of intra-abdominal pressure (baseline, 18, and 22 mmHg) were randomly generated. At each level of intra-abdominal pressure, three levels of PEEP were randomly applied: baseline (5 cmH₂O), moderate (0.5 × intra-abdominal pressure), and high (1.0 × intra-abdominal pressure). We measured end-expiratory lung volumes, arterial oxygen levels, respiratory mechanics, and cardiac output 10 minutes after each new IAP and PEEP setting.

Results

At baseline PEEP, IAH (22 mmHg) decreased oxygen levels (-55%, P <0.001) and end-expiratory lung volumes (-45%, P = 0.007). At IAP of 22 mmHg, moderate and high PEEP increased oxygen levels (+60%, P = 0.04 and +162%, P <0.001) and end-expiratory lung volume (+44%, P = 0.02 and +279%, P <0.001) and high PEEP reduced cardiac output (-30%, P = 0.04). Shunt and dead-space fraction inversely correlated with oxygen levels and end-expiratory lung volumes. In the presence of IAH, lung, chest wall and respiratory system elastance increased. Subsequently, PEEP decreased respiratory system elastance by decreasing chest wall elastance.

Conclusions

In a porcine sick lung model of IAH, PEEP matched to intra-abdominal pressure led to increased lung volumes and oxygenation and decreased chest wall elastance shunt and dead-space fraction. High PEEP decreased cardiac output. The study shows that lung injury influences the effects of IAH and PEEP on oxygenation and respiratory mechanics. Our findings support the application of PEEP in the setting of acute lung injury and IAH.     

Comparison of different methods for measuring intra-abdominal pressure

OBJECTIVE: Intra-abdominal pressure (IAP) can be measured in different ways but is usually measured indirectly via the urinary bladder. The aim of the study was to: 1) compare urinary bladder pressure, femoral vein pressure, and inferior caval vein pressure with IAP at different levels of IAP; and 2) try to find an optimal amount of fluid to be instilled into the urinary bladder before measurement of the bladder pressure, and to compare changes in blood flow in the femoral vein with that in the caval vein at different pressure levels. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: Eight domestic swine of both sexes, weighing 30.6+/-2.9 kg (mean+/-SD). INTERVENTIONS: Catheters connected to pressure transducers were placed into the urinary bladder, the inferior caval vein, the femoral vein, and the superior caval vein. Transit time flow probes were placed around the inferior caval vein and the femoral vein. After a stabilizing period, the abdominal pressure was increased stepwise by instillation of Ringer's solution into the abdomen and then decreased. Thereafter, we instilled fluid into the bladder at an IAP of 8 mmHg and at 20 mmHg and measured the amount of fluid needed to elevate the intra-vesical pressure by 2 mmHg. RESULTS: The pressures recorded in the urinary bladder, the inferior caval vein, and the femoral vein reflected the pressure in the abdominal cavity very well. The fluid volume needed to increase the bladder pressure by 2 mmHg was significantly lower at 20 mmHg IAP than at 8 mmHg. Blood flow in the femoral vein and the inferior caval vein showed a similar pattern and decreased when the intra-abdominal pressure increased. CONCLUSIONS: In our porcine model, and increasing the IAP by means of instillation of Ringer's solution, a reliable estimation of the IAP was obtained by measuring the pressure in the urinary bladder, the femoral vein or the inferior caval vein. The IAP estimated indirectly as the urinary bladder pressure is affected by the amount of fluid in the bladder, which should not exceed 10-15 ml. The decrease in femoral vein blood flow reflects the changes in inferior caval vein flow during increased IAP.     

Intra-abdominal pressure measurements using a wireless radio pressure pill and two wire connected pressure transducers: a comparison

Intra-abdominal pressures were measured simultaneously with a wireless radio pill and two wire-connected pressure transducers introduced orally and rectally respectively. Measurements were made on 8 men during common postures, simple activities and static and dynamic lifting. An acceptable correspondence was found in wave forms of the generated pressure curves in time and shape. The three systems showed, however, a less good agreement in recorded peak differences, i.e. highest and lowest pressure responses to each task. The radio pill is simple to use, but more difficult to calibrate and expensive, compared to the wire-connected methods, which however are less attractive for use in the work environment.     

Estimation of central venous pressure using inferior vena caval pressure from a femoral endovascular cooling catheter

Purpose

Endovascular cooling using the femoral cooling catheter is widely practiced. Central venous pressure (CVP) monitoring in patients undergoing femoral endovascular cooling may require the placement of another catheter near the right atrium (RA). We sought to estimate the agreement between the CVP recorded from catheters placed in the superior vena caval pressure (SVCP) and the inferior vena caval pressure (IVCP) recorded from the femoral cooling catheter in patients undergoing femoral endovascular cooling.

Methods

We enrolled adult cardiac arrest survivors undergoing femoral endovascular cooling. A commercially available central venous catheter was placed in the SVC (superior vena cava) near the RA via subclavian venous access. Both SVCP and IVCP were recorded every 4 hours during therapeutic hypothermia. Arterial pressure, heart rate, peak inspiratory pressure (PIP), and positive end expiratory pressure (PEEP) at the time of vena caval pressure measurements were obtained.

Results

A total of 323 pairs of SVCP and IVCP measurements were collected. The correlation coefficient between SVCP and IVCP was 0.965 (P < .001). The mean difference between SVCP and IVCP was − 0.45 mm Hg (SD, 1.27; 95% confidence interval, − 0.59 to − 0.31 mm Hg). The limits of agreement were − 2.94 to 2.05 mm Hg. Vena caval pressures were significantly correlated with airway pressures (peak inspiratory pressure and positive end expiratory pressure), whereas the difference between SVCP and IVCP did not correlate with airway pressures.

Conclusion

Inferior vena caval pressure measured via the femoral cooling catheter showed excellent agreement with CVP recorded from catheters placed in the SVC, which indicates that the femoral cooling catheter can be used for monitoring CVP.     

Non-invasive measurement of intra-abdominal pressure: a preliminary study

The importance of measuring intra-abdominal pressure (IAP) has increased since the negative effects of sustained increased IAP, also known as intra-abdominal hypertension (IAH), have become known. The relation between IAP and abdominal wall tension has been included in several reports. We have developed a device to measure abdominal wall tension by measuring force and distance. This device enables us to investigate the correlation between the abdominal wall tension and IAP. The abdomens of two corpses (one female, one male) were insufflated with air. IAP was increased and measured at intervals by means of a laparoscopic set-up. Abdominal tension was measured at seven points on the abdominal wall at each interval. Pearson's correlation coefficients were used to determine the relationship between IAP and tension for each point measured. ANOVA was used to assess relations between measured tensions versus applied pressure, locations and subjects. In both corpses, all points showed significant (p < 0.001) correlations between IAP and abdominal wall tension. The points along the mid transverse plane appear to be more similar compared to more cranial and caudal points. We have assessed the feasibility of a device that non-invasively can track changes in IAP. Measurements performed with the device are preliminary results, and further investigation is needed.     

应用图文资料宣教对患者使用气垫床依从性的影响

目的 探讨应用图文资料宣教对患者使用气垫床依从性的影响。 方法 选择2009年1月-2011年12月收治的难免压疮、神志清楚的患者48例,按随机数字表法分为观察组和对照组各24例。对照组口头给予患者压疮相关知识宣教,观察组在此基础上给予压疮相关知识的图文资料进行宣教。观察2组使用气垫床的依从性。 结果 观察组依从率91.7%,高于对照组的66.7%。 结论 采用口头宣教与图文资料宣教相结合的方法能明显提高患者使用气垫床的依从性,减轻护理工作量。     

Semi-recumbent position and body mass percentiles: effects on intra-abdominal pressure measurements in critically ill children

Purpose  

Patient position and body mass index (BMI) affect intra-abdominal pressure (IAP) measured by the intra-vesical method in adults. We sought to determine effects of patient position and BMI on IAP in children because accurate measurement and interpretation of IAP are important for patient management.     

In-shoe pressure measurements with a viscoelastic heel orthosis.

OBJECTIVE: To detect the mechanical effect of a viscoelastic heel orthosis. DESIGN: Two-factor analysis of variance with interactions between the orthosis and the subjects. The number of subjects was determined by presuming the effect of the orthosis to be twice as large as the error-free standard deviation (SD) of the interactions, the step-to-step SD four times as large as the error-free SD of the interactions, type 1 error probability equal to .05, and type 2 error probability equal to .20. SETTING: A gait laboratory in a university hospital. SUBJECTS: Twenty-two consecutive patients with treated heel pain. MAIN OUTCOME MEASURES: Peak pressure (PP), pressure-time integral (PTI), and foot-to-sensor contact time (CoT) measured for five steps at 24 discrete sensors of predetermined positions in the foot with treated heel pain. RESULTS: The orthosis reduced PPs, PTIs, and CoT (p < .05) in the median midfoot and lateral midfoot; reduced PPs and PTIs (p < .05) in the posterior heel and medial midfoot; increased PP and PTI (p < .05) in the anterior part of the first metatarsal head; and increased PTI (p < .05) in the lateral part of the hallux. The ratios of the estimated step-to-step SDs to the estimated error-free SDs of the interactions of PPs, PTIs, and CoT were less than four at all the sensors. CONCLUSION: Proper design and estimation of the variations ensured that there was sufficient power to detect the effect of an a priori specified size as statistically significant: the orthosis reduced the mechanical loads in the posterior heel and the midfoot and increased the mechanical loads in the anterior part of the first metatarsal head and the lateral part of the hallux during walking.     

Nursing care for raised intra-abdominal pressure and abdominal decompression in the critically ill.

Abdominal assessment is one of a number of continuous assessments that critical care nurses undertake. Since 1988 in the Department of Critical Care Medicine (DCCM), the technique of abdominal decompression has become another therapy for severe critical illness. The critical care nurse requires to have an understanding of raised intra-abdominal pressure assessment, pressure measurement and the care of abdominal polypropylene mesh insertion in the critical care setting. Our experience has been that the use of polypropylene mesh insertion halved since 1993. A retrospective study (Torrie et al. 1996) of 68 occasions (64 patients) of polypropylene mesh insertion, showed that seven patients developed fistulas and 32 patients died. There was no dehiscence of the mesh from the fascia. Forty-two wounds had primary fascial closure (28 with primary skin closure, 3 with secondary skin closure, 11 left to granulate) and 3 of them later dehisced. At follow-up (27 patients, median 7.5 months), 6 had stitch sinuses, and 5 had incisional hernias. Care of patients with polypropylene mesh inserted requires vigilant nursing practice but decompression of raised intra-abdominal pressure can be life-saving and complications are manageable.