Biomedical subjects

M H Morgalla

Publications and source records attributed to M H Morgalla.

9 recordsLinked to original sources

PubMed2006

[Coma. The prognostic value of evoked potentials in patients after traumatic brain injury].

BACKGROUND: The prognosis after traumatic coma is often unclear. We investigated the prognostic value of somatosensory (SSEP) and early acoustic (EAEP) evoked potentials on comatose patients in the intensive care unit regarding long-term outcome. Different evaluation systems were investigated. METHODS: This was a retrospective analysis of 100 patients. SSEP and EAEP were examined at different times and analysed according to the Riffel score. Combinations of the different types of potentials were evaluated regarding possible improvement of outcome prediction. RESULTS: The positive predictive value of at least one missing peak V of the EAEP regarding a fatal prognosis was 83%. The negative predictive value of the EAEP was 96%. A good outcome (GOS 4+5) could be predicted by bilateral normal SSEP and EAEP with a positive predictive value of 98%. CONCLUSIONS: Early evaluation of SSEP and EAEP allows reliable prognostic predictions regarding a later outcome in patients with severe traumatic brain injury and should therefore be used more often for intensive care patients.

Brain Injuries↗

PubMed2002

The problem of long-term ICP drift assessment: improvement by use of the ICP drift index.

BACKGROUND: Intracranial pressure (ICP) monitoring is dependent on the precise measurement of absolute pressures and low drifts of the different transducers in use. Our investigations have shown that probes sometimes appear to reveal positive and negative drifts consecutively. There is no regard for any of these important pressure changes by the mere result of the traditional drift. Therefore, we have developed a more precise way of assessing the behavior of the ICP drift. METHOD: A special laboratory set up for the simulation of constant pressures, at definite temperatures, was designed. We examined the Camino-110-4B, Gaeltec ICT/B, HanniSet and Spiegelberg transducers. Drift index is a new term that has been developed by our group to provide a better description of the actual pressure changes over long-term measurement. The drift index consists of three parameters: the percentage of measurements which show a pressure change during the 10 days of measurement; the maximum absolute pressure deviation that occurred during a ten day measurement; and the mean absolute pressure deviation during a 10 day measurement. FINDINGS: The median proportion of pressure changes during ten days were: Camino: 1.59%; Gaeltec: 0.71%; HanniSet: 0.08%; Spiegelberg: 4.00%; The median maximum absolute pressure changes were 6; 9.5; 1; and 11 mmHg for the four types and the median mean absolute pressure changes were 2.9; 5.1; 0; and 2.4 mmHg, respectively. The median 10 day classical drift in each type of transducer was 4; 9; 0; and 2 mmHg, respectively. INTERPRETATION: We recommend the use of the drift index to be used by manufacturers. This is an additional vital parameter in order to improve ICP measurement accuracy and the proficiency of ICP monitoring.

Equipment Design↗

PubMed2001

Methods of experimental and clinical assessment of the relative measurement accuracy of an intracranial pressure transducer. Technical note.

The assessment of the actual measurement accuracy of an intracranial pressure (ICP) transducer is imperative but still very difficult in practice. The authors tested the Codman MicroSensor ICP transducer experimentally. Additionally, a bedside test for assessment of measurement accuracy was used before and after clinical monitoring. For laboratory testing, seven new transducers were examined for measurement accuracy at increasing pressures ranging from 0 to 75 mm Hg. Drift was evaluated for 10 days at six different pressure levels ranging from 0 to 50 mm Hg. Temperature drift was assessed over a temperature range from 20 to 45 degrees C. The percentage absolute difference was used in the assessment of measurement accuracy. For clinical testing, measurement accuracy was assessed intraoperatively just before the insertion of the transducer and in an open water bath after its explantation, at 10 cm H2O both times. The maximum percentage absolute difference was 9% at a pressure of 10 mm Hg, and declined toward 2.3% at a pressure of 75 mm Hg. The maximum drift over 10 days was -4 mm Hg. Within the range of 30 to 40 degrees C, temperature drift was negligible. Over a period of 2 years, between June 1997 and June 1999, 40 ICP transducers were implanted in 35 patients by one surgeon. Of these devices, a malfunction was detected in two of them by testing them in a water bath before insertion. Experimental and clinical results indicate that this miniature strain-gauge transducer measures accurately; however, control readings for the probe by means of measurement in an open water bath just before insertion are strongly recommended.

Equipment Design↗

PubMed1999

A computer-based method for continuous single pulse analysis of intracranial pressure waves.

INTRODUCTION: The single pulse analysis of intracranial pressure waves provides valuable information about the autoregulative processes after head injury. This method has not been used for routine clinical assessment as yet. Current methods for evaluation of intracranial pressure waves are based on spectral analysis or related techniques. This imposes restrictions on the wave sequences available for the investigation of ICP attributes. Therefore, we have developed a computer-based method, which enables continuous analysis of each pulse of the ICP wave, in any clinical setting. METHOD: Firstly, the raw data of the ICP wave is continuously recorded by the Multifunctional Anaesthetic Record System (MARS, Hewlett Packard). The recorded data is then subjected to single pulse wave analysis by our software. Each single pulse is identified by the algorithm. The maximum, minimum and mean value, as well as amplitude and gradient are calculated in each pulse pressure. All conceivable correlations of the listed parameters can be examined. RESULTS: We applied our software in 9 cases with head injury and evaluated the measurements over 59 days (1400 h). More than 7 million single pulse pressures have been analyzed off-line. The software proved to be accurate and easy to apply. It was possible to calculate correlations between the different wave attributes on a broad basis of data. Parameters of special clinical interest were the amplitude of the single pulse pressure and the gradient. CONCLUSION: This method is an improvement on ICP single pulse pressure analysis and facilitates its clinical application. It creates the possibility for continuous long-term analysis of the ICP wave attributes under any clinical condition without loss of data. There are indications that the amplitude and the gradient of the ICP pulse pressure could provide valuable additional information for clinical assessment. However, further evaluation is required.

Craniocerebral Trauma↗

PubMed1999

[Measurement technique. Systems and methods for intracranial pressure monitoring].

GOAL: Intracranial pressure (ICP) monitoring has a key role within the neuromonitoring, although ICP does not monitor processes of the central neuron directly and only with delay. One of the important factors in ICP monitoring is measurement accuracy. For a better understanding of ICP probes and their differences, the function and principles of intracranial pressure transducers should be evaluated from a technical point of view. METHOD: The principles of ICP measurement were analyzed and compared. Practical applications of these principles were examined and examples of different ICP probes were discussed regarding their mode of pressure transformation. The technical advances of ICP monitoring were analyzed. RESULTS: Since LUNDBERG, a variety of different types of transducers has been developed. Ventricular ICP monitoring has been supplemented by extradural and intraparenchymatous probes. An increasing miniaturization of the transducers has emerged. Additionally, fiberoptic systems have been developed. Latest developments include multifunctional ICP probes. So far, the main problem of most types of transducers consists in the inability to assess measurement accuracy of a probe during the period of patient monitoring. CONCLUSION: ICP probes should be tested better for correct function by the manufacturer prior to sale. External controls of the measurement accuracy should be performed more frequently to ensure constant quality. Future ICP transducers have still to be more cost-effective.

Humans↗

PubMed1997

ICP monitoring with a re-usable transducer: experimental and clinical evaluation of the Gaeltec ICT/b pressure probe.

Intracranial pressure monitoring requires reliable transducers at a justifiable price. At present, transducers for single or repeated use are available. We examined the Gaeltec model ITC/b solid state miniature transducer experimentally and clinically. Measurement accuracy was assessed in vitro at increasing steps of 5 mmHg from 0 to 80 mmHg. While new and recently serviced probes revealed minimal deviations from the preset values, frequently used transducers differed up to 7 mmHg. This occurred especially in the high pressure range above 50 mmHg. Additionally the drift was investigated at different pressure levels. After 24 hours we already found drifts of 2 mmHg with new and serviced probes and up to 4 mmHg with used ones. In clinical practice we implanted 150 transducers in 121 patients from 1983 until 1995. The probes were re-used up to twelve times, the average time being 7 times. 32.7% of all measurements were regarded as not reliable. Dislocation (16.7%), inability to calibrate (3.3%) and defect pressure probes (3.3%) were the most common complications. Repeated use of the Gaeltec ICT/b probe also seemed to result in an additional decay of measurement quality. The strain of frequent cleaning and sterilizing may have caused changes of the physical properties of the probes with time. Whether these results also apply to other types of ICP probes for repeated use needs further evaluation.

Adolescent↗

PubMed1995

Repeated decompressive craniectomy after head injury in children: two successful cases as result of improved neuromonitoring.

BACKGROUND Decompressive craniectomy in the treatment of posttraumatic brain swelling is not generally accepted. Until now the efficacy of operative decompressive craniectomy in posttraumatic brain swelling of children appeared more promising. However, the criteria for such procedures remain unclearly defined. METHODS We present two children who had repeated decompressive craniectomy following head injury, in order to control intracranial pressure (ICP) sufficiently. Our indications for performing a decompressive craniectomy in the presence of conservatively uncontrollable raised ICP are: (1) Patient is between the ages of 3 and 35 years. (2) An initial Glasgow Coma Scale (GCS) ranging between 4 and 8. (3) Three criteria have to be fulfilled at the same time: The cerebral perfusion pressure (CPP) has to drop to values of less than 60 mm Hg. It is impossible to control the ICP values (up to 45 mm Hg) conservatively. The diastolic velocity of the transcranial doppler sonography (TCD) has to decrease until only a systolic flow pattern is obtained. (4) No other mass lesion should be detected on cranial computed tomography (CCT) that could account for the rise in pressure. In both cases we performed bifrontal decompressive craniectomies. RESULTS Both patients survived. Seven months after the accident, patient No. 1 was oriented and could walk on her own with a mild right-side hemiparesis. Patient No. 2 could attend school 12 months postinjury. Both patients developed hygromas after the craniectomy. A shunt operation, however, was not necessary. CONCLUSIONS ICP monitoring, together with CCT examination, simultaneous recording of TCD, and systemic parameters, will reveal a patient at risk at a time when impending damage due to uncontrollable ICP may still be prevented. The simultaneous assessment of cerebral blood flow by transcranial doppler (TCD), in this situation, proves most valuable. It improves the guidelines of patient selection for decompressive craniectomy, in the presence of conservatively uncontrollable ICP.

Brain Edema↗

PubMedDate not supplied

ICP measurement control: laboratory test of 7 types of intracranial pressure transducers.

Intracranial pressure (ICP) monitoring has become an important parameter in the assessment of comatose patients, with raised intracranial pressure. The transducers in use have to fulfill the criteria of measurement accuracy, practicability and cost-effectiveness. However, these requirements are not always met in clinical practice. The need for ongoing quality control through independent laboratories remains. We have developed a laboratory set-up for the evaluation of intracranial pressure probes. Seven different types of currently used transducers have been tested for measurement accuracy. Under in vitro conditions 3 parameters were assessed: measurement accuracy, a 24 h drift and 10 day drifts. Tests for measurement accuracy were performed at increasing pressure levels of up to 80 mmHg. They were repeated 10 times per probe. This test allowed the simultaneous assessment of 5 different ICP probes. Drift was evaluated for 24 h and 10 days, at 6 pressure levels between 0 and 50 mmHg. Seven different types of ICP probes were tested (HanniSet, Camino, Codman, Spiegelberg, Medex, Epidyn and Gaeltec). Measurement accuracy was best with HanniSet probes. The maximum errors with this transducer were 3 mmHg. Camino and Codman showed similar results. Spiegelberg had slightly larger deviations. With Epidyn and Gaeltec the highest error were noted, up to 10 mmHg in the high pressure range. The 24 h drift was lowest with HanniSet (0.2 mmHg) and Camino (0.8 mmHg). The largest drifts were seen with Medex, Spiegelberg and Gaeltec (1.8 mmHg). Ten day drift was lowest with HanniSet (0.1 mmHg/day) and Codman (0.2 mmHg/day). The highest long-term drifts were found with Epidyn and Gaeltec (1.5 mmHg/day). Drift did not exhibit a linear pattern. After an initial rise in drift during the first 24-72 h, it decreased slowly during the next 7 days. Most ICP probes revealed measurement inaccuracy and drift. These results emphasize the necessity for ongoing evaluations of ICP probes. Therefore, tests for quality assurance are essential to establish a consistent standard of proficiency of ICP transducers.

Intracranial Pressure↗

PubMedDate not supplied

ICP measurement accuracy: the effect of temperature drift. Design of a laboratory test for assessment of ICP transducers.

Intracranial pressure (ICP) monitoring has become the mainstay of multimodal neuromonitoring of comatous patients after head injury. In the presence of rising ICP and faced with pressures, difficult to control, aggressive measures, such as hypothermia may be used. The ICP readings should not be influenced by temperature changes. A laboratory test was designed to simulate temperature variations between 20 degrees C and 45 degrees C at different pressure levels under physiological conditions. Five types of transducers were examined: Epidyn Braun Melsungen, ICT/B-Titan Gaeltec, Camino-OLM-110-4B, Codman MicroSensor ICP-Transducer, Neurovent ICP transducer Rehau Ag+Co. Tests were performed at 6 different pressure levels between 0 mmHg and 50 mmHg. The results show very low drifts of less than 0.15 mmHg degree C-1 for Codman, Epidyn and Neurovent. Gaeltec and Camino exhibited higher drifts of 0.18 mmHg and 0.2 mmHg degree C-1 respectively. Within the temperature range from 35 degrees C to 42 degrees C all probes tested show insignificant temperature drift. Whether these results also apply to other types of transducers needs further evaluation. Problems and requirements related to the design of a laboratory test for the in vitro assessment of ICP transducers are discussed in detail.

Biomedical Engineering↗