股静脉测压法和膀胱测压法在危重患者腹内压监测中的比较

目的：比较股静脉测压法和膀胱测压法在危重患者腹内压（IAP）监测中的应用价值.方法：对2013年1-6月住院治疗的20例ICU重症患者,分别使用两种测压方法进行IAP监测,均每8 h 1次,连续测定3 d,每次随机选择两种方法的测量顺序,共测量720次,比较两种测压法在读数精准性、测压数值、操作时间、并发症和医护人员满意度等方面的异同.结果：股静脉测压法所测压力数值与膀胱测压法相近[（14.14±4.33）mmHg比（12.91±4.75）mmHg,P〉0.05];但是股静脉测压法的操作时间[（57.94±19.00）s]较膀胱测压法更短[（112.49±27.07）s,P〈0.05];股静脉测压法读数精准率（84.44%）较膀胱测压法（49.44%）高（P〈0.01）,操作并发症低至1.1%（4例次）,远低于膀胱测压法的5.3%（19例次,P〈0.05）;医护人员满意度达（3.90±0.26）分,优于膀胱测压法[（2.48±0.19）分,P〈0.01].结论：相对于膀胱测压法而言,股静脉测压法具有测压值相似、操作时间短、读数精准度高、操作并发症少、接纳度高等优点,值得在危重患者IAP监测中推广.     

Clinical evaluation of a simple epidural pressure sensor

Summary The Plastimed^® epidural pressure sensor was evaluated in 35 patients, twenty-eight of whom were suffering from head injury. In seven patients simultaneous intraventricular pressure measurements were obtained. The epidural pressure sensor was only functioning satisfactorily in approximately 2/3 of the patients, while it was malfunctioning or not functioning in the remainder. In seven comparable IVP/EDP studies significant differences up to 25 mm Hg were noted. In three patients IVP was greater than EDP. In two patients the opposite was true. No significant complications were observed.These unsatisfactory results have made us abandon the technique and resort to intraventricular or subarachnoidal pressure measurements.     

Clinical evaluation of a new epidural pressure monitor

Summary Comparative measuring of epidural pressure using the Spiegelberg probe 1 and ventricular fluid pressure was carried out in 15 neurosurgical intensive-care patients. Deviations in both directions were established, with a trend toward overestimating ventricular pressure in epidural pressure measuring (r=0.77). Individual pulsations, spontaneous wave courses and therapy-induced pressure changes were reflected without delays. There were no complications observed with probe implantation periods for up to 6 days. The system has been shown to be mechanically stable and easy to implant. We believe the device to be fit for trend monitoring of intracranial pressure. As with other epidural pressure monitoring systems, false assessments of ventricular pressure may lead to wrong decisions as to the required therapy.     

The Rotterdam teletransducer: State of the device

Summary The developments of a telemetric device for monitoring intracranial pressure, the Rotterdam Teletransducer, are described. The major problem in telemetric pressure sensing devices consists of diffusion of water into the transducer, resulting in unpredictable zero drift. Therefore, special attention was paid to bonding techniques for sealing the transducer.The results of improved epoxy sealing, active metal brazing and glass bonding are described. In vitro tests showed transducers sealed with epoxy resin to be stable for two months. Using the more complicated tchniques of glass bonding and active metal brazing, hermetic seals could be achieved with stable transducers for over one year. In vivo functioning of the Rotterdam Teletransducer was tested in acute and chronic animal experiments. The in vivo results corresponded to those obtained in the in vitro experiments. Regression analysis between epidural and ventricular fluid pressure showed a one to one ratio.Results of clinical application of the device in 22 patients are described. Accurate depth setting of the transducer on the dura, according to the pressure depth curve, was shown to be essential.The device has also been used with success for non-invasive fontanelle pressure measurements in infants. The depth positioning of the transducer on the fontanelle according to a pressure depth curve is described.This paper has been awarded by the 1985 Casey Holter Memorial Prize by the Society for Research in Hydrocephalus and Spina Bifida.     

Idiopathic normal pressure hydrocephalus: Analysis of factors related to cerebrospinal fluid dynamics determining functional prognosis

Summary This investigation has been undertaken to analyze the findings with both the cerebrospinal fluid (CSF) pressure (Pcsf) and CSF pulse pressure (PP) in order to predict the outcome of patients with the syndrome of idiopathic normal pressure hydrocephalus (NPH). Accordingly, a prospective clinical study was planned in which two groups of patients with NPH, having analogous prevalence of several matched clinical and radiological parameters, were separated on the basis of their positive or negative response to shunting. Both the resting Pcsf and CSF PP profiles were compared in these two groups, and between them and normal controls. CSF PP amplitude and CSF PP latency correlated directly in conditions associated with either normal or high compliance (controls and patients with Alzheimer-like disorders), whereas this correlation was inverse in states of low compliance (NPH). On the other hand, shunt-responders showed a resting Pcsf significantly higher than both non-responders and controls.The following conclusions were obtained: 1) CSF PP is a high-amplitude and relative low-latency wave in NPH when compared with controls; 2) CSF PP amplitude and latency correlate directly in normal subjects and in those with primary cerebral atrophy; 3) a non-reversible stage of NPH could be conceived in contradistinction to the reversible one, in both of which an inverse correlation between the amplitude and the latency takes place, the main difference between them being the resting Pcsf, which is significantly lower in the former than in the latter, depending on the degree of atrophic changes developed.     

膀胱压、胃内压与腹内压的相关性研究

目的 探讨利用膀胱压、胃内压来间接监测腹内压的可行性．以便于腹腔间隔室综合征(ACS)的诊断。方法 对24例行腹腔镜胆囊摘除术(LC)患者进行前瞻性对照研究。在行LC时，在腹内压为10、15、20及25mmHg时同时测定膀胱压和胃内压。结果 腹内压与膀胱压的回归方程为Y=-10.193 1.228X．相关系数为0.941；腹内压与胃内压的回归方程为Y=-7.408 1.478X，相关系数为0.996。由此表明．腹内压与膀胱压和胃内压呈显著正相关。结论 腹内压与胃内压和膀胱压有很好的相关性，可以利用胃内压和膀胱压来反映实际腹内压。     

间歇正压通气和呼气末正压通气对犬眼内压的影响

目的 探讨间歇正压通气(IPPV)和呼气末正压通气(PEEP)对犬眼内压(10P)的影响.方法 实验犬8只,麻醉后分别监测基础条件下和各种机械通气条件下的IOP、CVP、MAP.结果 实施20 ml/kg和30 ml/kg两种不同潮气量的IPPV时IOP差异无统计学意义.实施10、15、20cm H20三种不同压力值的PEEP时IOP均显著升高(P<0.01).结论 IPPV对IOP影响不大,PEEP可使IOP显著升高.     

防压疮气垫床压力选择的实证研究与分析

目的探讨临床防压疮气垫床的最佳压力。方法在改装设备测量气垫床压力和骶尾部压力的基础上,采用重复测量方法,选择76名健康志愿者仰卧于气垫床上,气垫床压力由充满逐渐降低,每降低5mmHg记录1次骶尾部压力;使用混合效应二次曲线模型分析气垫床压力与骶尾部压力的关系,通过固定效应确定最佳的气垫床压力,并根据个体随机效应分析气垫床压力的最佳范围。结果气垫床压力和骶尾部压力呈二次项分布,可以采用混合效应二次曲线模型进行分析;通过固定效应分析可得气垫床的最佳压力为24.55mmHg,根据个体随机效应分析可得气垫床的压力范围在20.23~29.40mmHg时,人体骶尾部所受的压力最低,与其他范围相比差异具有统计学意义(均P0.01)。结论气垫床最佳压力范围为20.23~29.40mmHg。     

A practical technique for continuous monitoring of cerebral tissue pressure in neurosurgical patients

Summary A new technique for continuous monitoring of cerebral tissue pressure is presented. It is based on a new type of piecoresistive microtransducer with low baseline and temperature drifts. In 7 patients cerebral tissue pressure and ventricular fluid pressure were recorded simultaneously.Comparison of these two different pressures showed extremely good correlation with coefficients always better than 0.95. Due to another type of pulsewave cerebral tissue pressure was constantly 4 to 12 mm Hg lower than ventricular fluid pressure. Routine use of cerebral tissue monitoring in 12 neurosurgical patients with brain tumours postoperatively showed good clinical correlation of cerebral tissue pressure without any additional complications.The authors recommend continuous monitoring of cerebral tissue pressure as a safe and simple method of intracranial pressure monitoring in neurosurgery.     

Telemetric recording of intrapleural pressure

BACKGROUND: Monitoring of intrapleural pressure (IPP) is used for evaluation of lung function in a number of pathophysiological conditions. We describe a telemetric method of non-invasive monitoring of the IPP in conscious animals intermittently or continuously for a prolonged period of time. MATERIALS AND METHODS: After IACUC approval, six mongrel dogs were used for the study. After sedation, each dog was intubated and anesthetized using 0.5% Isoflurane. A telemetric implant model TL11M2-D70-PCT from Data Science International was secured subcutaneously. The pressure sensor tip of the catheter from the implant was inserted into the pleural space, and the catheter was secured with sutures. The IPP signals were recorded at a sampling rate of 100 points/second for 30 to 60 min daily for 4 days. From these recordings, the total mean negative IPP (mmHg), and the total mean negative IPP for a standard time of 30 min were calculated. In addition, the actual inspiratory and expiratory pressures were also measured from stable recording of the IPP waveforms. RESULTS: In six dogs, the total mean +/- SD negative IPP was -10.8 +/- 10.6 mmHg. After normalizing with respect to acquisition time it was -13.2 +/- 11.2 mmHg/min. The actual inspiratory pressure was -19.7 +/- 15.3, and the expiratory pressure was -11.0 +/- 12.9. CONCLUSIONS: Our study demonstrates that telemetric monitoring of IPP can be performed reliably and non-invasively in conscious experimental animals. The values for IPP in our study are compatible with the results of other investigators who used different methods of IPP measurement. Further work may show this method to be helpful in understanding the pathophysiology of various breathing disorders.     

Iliac venous pressure estimates central venous pressure after laparotomy

Background

Central venous pressure (CVP) is traditionally obtained through subclavian or internal jugular central catheters; however, many patients who could benefit from CVP monitoring have only femoral lines. The accuracy of illiac venous pressure (IVP) as a measure of CVP is unknown, particularly following laparotomy.

Methods

This was a prospective, observational study. Patients who had both internal jugular or subclavian lines and femoral lines already in place were eligible for the study. Pressure measurements were taken from both lines in addition to measurement of bladder pressure, mean arterial pressure, and peak airway pressure. Data were evaluated using paired t-test, Bland-Altman analysis, and linear regression.

Results

Measurements were obtained from 40 patients, 26 of which had laparotomy. The mean difference between measurements was 2.2 mm Hg. There were no significant differences between patients who had laparotomy and nonsurgical patients (P = 0.93). Bland-Altman analysis revealed a bias of 1.63 ± 2.44 mm Hg. There was no correlation between IVP accuracy and bladder pressure, mean arterial pressure, or peak airway pressure.

Conclusions

IVP is an adequate measure of CVP, even in surgical patients who have had recent laparotomy. Measurement of IVP to guide resuscitation is encouraged in patients who have only femoral venous catheter access.     

Changes in intracranial pulse pressure amplitudes after shunt implantation and adjustment of shunt valve opening pressure in normal pressure hydrocephalus

Summary Background  We have previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (NPH) patients responding to shunt surgery. Whether or not shunt implantation or adjustment of the shunt valve opening pressure modifies the intracranial pulse pressure amplitudes in NPH patients remains to be established. This report summarises our observations. Patients and methods  Thirteen patients with NPH (idiopathic in nine and secondary in four) are presented in whom continuous intracranial pressure (ICP) monitoring was done before and after shunt implantation. In two, ICP monitoring was also done during adjustment of shunt valve opening pressure. The mean ICP and mean ICP wave amplitude (i.e. pulse pressure amplitudes) were determined in 6-s time windows. Results  After shunt implantation there was a fall in both mean ICP and mean ICP wave amplitude; the reduction in the two ICP parameters correlated significantly. However, mean ICP in the supine position was normal (i.e. <15 mmHg) in 12 of 13 patients before shunt placement, and remained normal after shunting. According to our criteria, the mean ICP wave amplitudes were elevated before shunting in 12 of 13 patients and became “normalised” the day after shunting in nine patients. The reduction in mean ICP wave amplitude after shunt was highly significant at the group level. Moreover, adjustment of shunt valve opening pressure modified the levels of mean ICP wave amplitudes. Conclusions  The present observations in 13 NPH patients indicate that shunt implantation reduces mean ICP wave amplitudes. Moreover, the level of reduction can be tailored by adjustment of the shunt valve opening pressure.     

Continuous urethral pressure measurement in women with unstable detrusor

To study the role of the urethra in bladder instability, we performed continuous urethrocystometry in 16 patients with verified unstable detrusor and found two qualitatively different pressure oscillations in the urethra: (1) continuous rhythmic pressure waves, characterized by frequency and pressure amplitude and (2) sudden and consistent urethral pressure drops of 35 cm H₂O occurring on average at mean time intervals of 3.5 seconds prior to the onset of the detrusor contraction. Simultaneous pelvic floor electromyographic (EMG) registration showed that the urethral pressure drop occurred either during decreased, unchanged, or increased pelvic floor activity. Restoration of the urethral pressure to its previous level was also unrelated to the pelvic floor EMG activity. Increased EMG activity at the onset of urethral pressure drops was not sufficient to suppress the urethral pressure drop, but could abolish the detrusor contraction. These findings suggest that the unstable detrusor is of a complex pathophysiological origin and involves both storage and micturition as well as detrusor and urethral function.     

Total and static pressure measurements of the male lower urinary tract

Simultaneous total and static urethral pressure measurements were attempted in 22 male subjects who could void around a 10-French bilumen urethral catheter. The catheter had an end-hole at its tip and a side-hole approximately 1 cm away from the end hole (short catheter-tip segment). Thus, during a single voiding attempt, simultaneous total and static urethral pressures at two different urethral sites (1 cm distance) could be recorded. In addition, suprapubic vesical pressure monitoring was done in all these subjects. The studies also included a comparison of these recordings with those obtained with a 10-French catheter that had its side-hole placed 10 cm away from the tip (long catheter-tip segment). The studies indicated that (1) the total pressure at a particular region of the urethra was usually higher than its static pressure; (2) the pressure sensing catheters produced “plugging effect” of the narrow segments of the outlet; and (3) the static pressure configurations that were obtained with a catheter having a long catheter-tip segment were markedly different from those obtained through a catheter that had a short catheter-tip segment. This presentation also includes observations on static pressure measurements obtained from a crude mechanical model that simulated the geometry of the urinary bladder and its outlet. True lateral pressures of the flowing fluid were obtained via cannulae inserted perpendicularly into the stream, through the wall of the outlet (extraluminal route). A comparison was attempted between the static pressure measurements obtained through the extraluminal route with those obtained through the catheters (10–14 French) that were directly inserted into the lumen of the outlet along its axis (intraluminal route). The studies indicated identical static pressures at the narrowest site (16–18 French) of the outlet recorded through both routes.     

Stroke volume of the heart and thoracic fluid content during head-up and head-down tilt in humans

BACKGROUND: The stroke volume (SV) of the heart depends on the diastolic volume but, for the intact organism, central pressures are applied widely to express the filling of the heart. METHODS: This study evaluates the interdependence of SV and thoracic electrical admittance of thoracic fluid content (TA) vs. the central venous (CVP), mean pulmonary artery (MPAP) and pulmonary artery wedge (PAWP) pressures during head-up (HUT) and head-down (HDT) tilt in nine healthy humans. RESULTS: From the supine position to 20 degrees HDT, SV [112 +/- 18 ml; mean +/- standard deviation (SD)], TA (30.8 +/- 7.1 mS) and CVP (3.6 +/- 0.9 mmHg) did not change significantly, whereas MPAP (from 13.9 +/- 2.7 to 16.1 +/- 2.5 mmHg) and PAWP (from 8.8 +/- 3.4 to 11.3 +/- 2.5 mmHg; P < 0.05) increased. Conversely, during 70 degrees HUT, SV (to 65 +/- 24 ml) decreased, together with CVP (to 0.9 +/- 1.4 mmHg; P < 0.001), MPAP (to 9.3 +/- 3.8 mmHg; P < 0.01), PAWP (to 0.7 +/- 3.3 mmHg; P < 0.001) and TA (to 26.7 +/- 6.8 mS; P < 0.01). However, from 20 to 50 min of HUT, SV decreased further (to 48 +/- 21 ml; P < 0.001), whereas the central pressures did not change significantly. CONCLUSIONS: During both HUT and HDT, SV of the heart changed with the thoracic fluid content rather than with the central vascular pressures. These findings confirm that the function of the heart relates to its volume rather than to its so-called filling pressures.     

Upright patient positioning in the management of intracranial hypertension

Utilizing either a subarachnoid screw or an intraventricular cannula, intracranial pressure was continuously monitored in 24 patients with established or potential neurological impairment of various etiologies. Marked diminution in intracranial pressure was observed in the sitting or semisitting position in the 13 patients with documented intracranial hypertension as well as in the 11 in whom intracranial pressure was not elevated. This sustained effect was noted even when superimposed on intensive medical management of intracranial hypertension.     

Splanchnic perfusion pressure: a better predictor of safe primary closure than intraabdominal pressure in neonatal gastroschisis

Background/Purpose

Both measured intraabdominal pressure (IAP) and calculated splanchnic perfusion pressure (SPP) have been advocated for use in operative management of gastroschisis. We directly compared these 2 clinical indices.

Methods

Institutional review board-approved multi-institutional retrospective review from 3 centers with 112 subjects. Splanchnic perfusion pressure was recorded as mean arterial pressure-IAP. We compared the clinical utility of IAP and SPP using univariate and multivariate regression analyses.

Results

Calculated mean SPP was higher among neonates requiring silo placement compared to those without (39.0 ± 1.9 vs 33.7 mm Hg, P < .01). Measured IAP levels were similar between groups (11.5 ± 1.1 vs 10.0 ± 0.5, mm Hg, P < .4). On a receiver operating characteristic curve, the inflection point for more than 90% specificity for silo placement was at an SPP of 44. In multivariate regression analysis adjusting for all factors below, SPP was independently associated with silo placement (odds ratio 1.2, 95% confidence interval 1.1-1.3, P < .01), and IAP was not (odds ratio 1.2, 95% confidence interval <1.0-1.5, P < .1).

Conclusions

These data suggest that SPP is a stronger predictor than IAP for the ability to achieve primary closure in the management of neonatal gastroschisis. We infer from these data that intraoperative SPP of more than 43 mm Hg may obviate the need for silo placement.