[Sound frequency analysis for identification of venous air embolism]

Air emboli occurring during surgery are considered to be life-threatening incidents. With the aim of achieving acoustic identification of venous air emboli, a frequency analysis of the sounds induced by an air embolism (millwheel murmurs) as well as of all other unusual sounds, was undertaken during 20 operations, and in experiments with animals. The frequency spectra of the sounds induced by air emboli are characterised by an increase in the amplitudes in the frequency range 1,100 to 3,000 Hz, while the amplitudes of normal heart sounds continuously decrease with increasing frequency. The frequency spectrum was examined for characteristics using an electronic filter system. The sounds induced by air emboli can be clearly distinguished from normal heart sounds. During operations on patients, suction sounds occur, the frequency patterns of which are not easy to distinguish from those of embolus-induced sounds, although an acoustic distinction can be made via a stethoscope or a loudspeaker. With optimal adjustment of the filter system, 73 out of 81 (90%) embolism-related sounds were correctly identified in animal experiments. On no occasion were normal heart sounds wrongly identified as due to an embolus. However, an embolus sound was frequently mimicked by interfering sounds such as those produced by artificial respiration, and other ambiend sounds. By modifying the oesophageal catheter to achieve optimal suppression of interfering sounds, this filter system could be developed into an alarm.

Evaluation of the efficacy of H1 blockers by noninvasive measurement techniques

BACKGROUND

Evaluation techniques for determining the strength of action and the onset of activity of H1 receptor blockers have not yet been sufficiently standardized.

OBJECTIVE

The clinical efficacy of the H1 receptor blocker loratadine was to be measured upon a wheal response subsequent to an intracutaneous injection of 0.1 ml histamine (0.1%).

METHODS

In a pilot study, 10 patients were treated with the H1 receptor blocker loratadine for a period of 7 days. Various noninvasive measurement techniques, i.e. 20-MHz sonography, laser-Doppler flowmetry, chromatometry using the Lab* system and computer-assisted planimetry, were applied to provide a quantitative evaluation of the wheal and the marginal erythema. Using these quantification methods, the development of the urticarial reaction 20 min after injection and its decline were evaluated.

RESULTS

The urticarial reaction was reduced substantially under treatment with 10 mg loratadine over a period of 7 days. The methods we used could accurately quantify different aspects of the urticarial reaction noninvasively.

CONCLUSIONS

All of the chosen measurement techniques are widely recognized. For objective assessment of the urticarial reaction with high-frequency ultrasound, we recommend the measurement of the distance between skin entrance echo and fascia since the demarcation of the wheal is often impossible by ultrasound. In order to improve comparison of results of various workgroups in the future, we therefore suggest the use of the selected combination of noninvasive procedures as a standard for evaluating the efficacy of H1 receptor blockers.

The hyperperfusion of the psoriatic plaque correlates histologically with dilatation of vessels

We examined psoriatic lesions on the upper legs in 20 patients, using a two-dimensional Laser-Doppler-Scanner (Laser Doppler Perfusion Imager LDI, Lisca Development, Linköping/Sweden). The plaques were evaluated weekly during therapy with dithranol. Five plaques were reconstructed three-dimensionally before and after therapy (reconstruction program ANAT 3D, SIS, Münster, Germany). The psoriatic plaque was represented in the Laser Doppler Perfusion image as a sharply demarcated, hyperperfused area. The perfusion of the plaques dropped during therapy with dithranol to just slightly increased values, compared with normal skin (2.04 arbitrary units AU, healthy skin 1.1 AU). Using three-dimensional reconstruction, we investigated the volume of dermal vessels and the density of papillae. When compared, the volume of papillary vessels was twice as large in psoriatic as in healthy skin. The number of the papillae per square millimetre, detected by three-dimensional reconstruction, was not reduced significantly during therapy. We think that the increased perfusion of the psoriatic plaque is due to the combination of morphological (dilatation of vessels), dynamic (increased blood flow) and optical effects (reduced scattering and increased sampling depth of the laser-beam in acanthotic tissue).

Psoriasis vulgaris in 50 MHz B-scan ultrasound--characteristic features of stratum corneum, epidermis and dermis

One hundred and forty fully developed, non-treated plaques of psoriasis vulgaris from the arms and legs of 22 patients were examined using 50 MHz B-scan ultrasound and compared with the images from adjacent, clinically normal skin. To visualize the dermis, high pre-amplification (digitization range 200 mV) was used, determined according to A-scan images. For evaluation of epidermal phenomena, low pre-amplification (digitization range 380 mV) was chosen in order to avoid overmodulation of the skin entry echo. In 10 patients, sonographic images were compared with histological sections from the exact same planes at the same magnification. At low pre-amplification, the skin entry echo is displayed as a markedly widened, frequently interrupted band composed of spots varying in thickness, height and echo density. Within these spots, several lamellae can be observed, represented as fine, echo-rich lines stacked one upon another. These phenomena correspond histologically to focal hyperparakeratosis, scaling and cracking of the stratum corneum. Due to the low amplification of the echo-signal the dermis is not visible. High pre-amplification allows evaluation of dermal changes. Below the entry echo there is an echopoor band (EPB) corresponding to the sum of acanthosis and infiltrate in the upper dermis. Underneath the EPB the dermis is represented as a zone with scattered internal echoes which are less intense than in normal skin. Dorsal shadows are typically present. They are artifacts emanating from epidermal regions with marked hyperkeratosis and disappear when the sonographic characteristics of the epidermis are changed, for instance by application of ointments prior to sonographic examination.(ABSTRACT TRUNCATED AT 250 WORDS)

[Right ventricular assist device (RVAD) in septic, fulminating pulmonary artery embolism]

We describe a 34-year-old male with pulmonary embolism. The patient had been admitted to a peripheral hospital for incision and drainage of a very large ischio-rectal abscess. Four days after successful surgical intervention and during a change of dressings he developed a massive pulmonary artery embolism. The patient was transferred to the Department of Cardiac Surgery in Graz; on arrival he had a cardiac arrest. Resuscitation was initiated and the patient was transferred to the operating theatre where emergency sternotomy and embolectomy revealed large thrombotic masses in the pulmonary circulation. Extracorporeal circulation was initiated, but despite aggressive medical measures (dopamine, dobutamine, isoproterenol, enoximone, and prostaglandin E1 in maximum therapeutic doses) and a long reperfusion time weaning was not possible. Despite the septic state, a right ventricular assist device (RVAD; ABIOMED BVS 5000) was installed. Weaning was finally accomplished with a pump flow of 2.2 l/min m2 and the patient transferred to the intensive care unit. On post-operative day 3 the pump flow was reduced to 2 l/min. The patient's condition remained stable, which made removal of the RVAD possible on postoperative day 5. The further course was uneventful, with secondary ischio-rectal wound closure. His initial psychomotor impairment had nearly disappeared and he was discharged 2 months later.

Cardiac allograft harvesting after carbon monoxide poisoning. Report of a successful orthotopic heart transplantation

Hearts from brain dead victims of carbon monoxide poisoning have been reported to be unsuitable for heart transplantation. We present the case of a 30-year-old male donor who was the victim of carbon monoxide poisoning. He was on ventilation for 16 days before the organs were offered for harvesting. A liver biopsy indicated focal liver cell necrosis. The liver graft was not used. Heart transplantation was performed successfully. No evidence of ischemic areas or myocardial cell necrosis could be found in all heart biopsy specimens. Four months after transplantation, graft function remains excellent.

Prostaglandin E1-induced moderation of elevated pulmonary vascular resistance. Survival on waiting list and results of orthotopic heart transplantation

Forty-three consecutive patients who were being treated with digitalis, angiotensin converting enzyme inhibitors, and diuretics were evaluated for orthotopic heart transplantation. After right heart catheterization in patients with more than 3 Wood units or with a mean pulmonary artery pressure higher than 30 mm Hg (n = 13; group 1), prostaglandin E1 (PGE1) therapy was initiated at a dosage of 5 ng/kg/min and was increased stepwise (mean maintenance dosage, 35 ng/kg/min) until side effects (joint pain, digital edema) occurred. After 6 days of PGE1 administration, dosage decreased stepwise. One week after PGE1 was stopped, right heart recatheterization was performed, and the patients were listed on the waiting list. Hemodynamic data significantly improved in PGE1-treated patients. Patients without pulmonary hypertension (group 2, n = 30) were put directly on the waiting list. No oversized or local donor was required for transplantation. Eight of 13 patients in group 1 underwent transplantation. The other five patients died while on the waiting list. In group 2, 15 patients underwent transplantation, and 15 patients died while on the waiting list. A prolonged mean survival time on the waiting list (6.0 versus 3.1 months, p < 0.005) was noticed in group 1. PGE1 was administered after orthotopic heart transplantation whenever indicated; no death was related to right ventricular failure in group 1. The results after orthotopic heart transplantation in patients treated with PGE1 were comparable to the control group. PGE1 therapy enabled us to perform orthotopic heart transplantation on patients with pulmonary hypertension at a comparable risk with normal heart transplant recipients.

Laparoscopic cholecystectomy after unsuccessful shock-wave therapy

Extracorporeal shock-wave therapy of gallstones was begun at the Surgical Department of the University of Freiburg, Germany, in March 1988; 85 patients were treated up to September 1991. The stone-free rate differed with the gallstone group. Patients with solitary stones less than 20 mm in diameter showed a significantly higher rate after 18 months of lithotripsy and dissolution therapy than patients with multiple stones (p < 0.01), that is, 83% and 49%, respectively. Open cholecystectomy was necessary for seven patients with complications following fragmentation. After starting laparoscopic cholecystectomy, eight patients decided in favor of this procedure because of constant biliary symptoms. These patients had a mean duration of dissolution therapy of 19 months. The minimal invasive procedure is an alternative for patients with unsuccessful lithotripsy and lysis who initially demanded conservative treatment. Indication for shock-wave therapy is limited to only a small group of patients with solitary cholesterol gallstones less than 20 mm who reject laparoscopic surgery.

Prostaglandin E1 reduces the frequency of rejection after heart transplantation

This retrospective study was carried out to evaluate the effect of prostaglandin E1 on the frequency of rejection in 36 heart transplant recipients who survived orthotopic heart transplantation for 60 days or longer. The therapy for both groups was the same except group 1 (n = 12) was given PGE1 for 6 to 14 days. Indication for the PGE1 was right ventricular mismatch or failure. The prostaglandin administration started during the transplantation procedure. The dosage was 28 to 64 ng/kg/min and was tapered down from 14.7 to 32 ng later. No major side effects related to PGE1 have been observed. During the first 60 days after heart transplantation, in the group treated with prostaglandin, rejection grade 2 or higher was evident in 0.91 biopsies/patient versus 2.2 in nontreated patients, (p less than 0.05). A prolonged interval free from rejection (p less than 0.05) was observed in the patients treated with prostaglandin.

Preoperative prostaglandin E1 treatment to prevent right ventricular failure after orthotopic heart transplantation

Elevated pulmonary vascular resistance (PVR) and pulmonary hypertension (PH) are high risk factors for early graft failure in orthotopic heart transplantation (oHTx). The need for an oversized donor in patients with elevated PVR aggravates the shortage of suitable donor organs. To decrease the elevated PVR to values suitable for orthotopic heart transplantation prostaglandin E1 (PGE1) was administered in 11 patients (11 male, mean age 49.2 years, mean dosage 35 ng/kg per min over 6-8 days). Ten days after the discontinuation of the PGE1 therapy, recatheterization was done. All haemodynamic data were determined by right heart catheterization using a Swan Ganz catheter and thermodilution technique before, and 10 days after, PGE1 treatment. The Wilcoxon signed ranks test was used for statistics. PVR significantly decreased in all patients (5.5 to 2.8 Wood units, P < 0.005). All patients were considered to be suitable for oHTX and put on the waiting list. At the time of writing, in eight of these patients (eight male, mean age 49.6 years; four ischemic, four dilatative CMP) oHTX had been successfully performed. No right ventricular failure occurred in the postoperative phase. These results sugest that long-term moderation of elevated PVR by PGE1 therapy weeks or months before transplantation enables oHTX in patients with elevated PVR.

[Noninvasive monitoring of rejection in heart transplant patients. An overview of current status and use at a small transplant center]

In view of the numerous techniques known for noninvasive rejection monitoring for heart transplant recipients, it is important, especially for small transplant centres, to select suitable parameters for routine monitoring. We verified the methods for rejection monitoring and on the basis of the good results after orthotopic heart transplantation in our unit (33 patients, 78% overall survival, no death later than 6 months after transplantation), consider the following parameters useful for small transplant centres: heart/thorax ratio, echocardiography and neopterin. The Fast-Fourier analysis should prove of great value for small transplant units, given the availability of suitable apparatuses.

Early surgical repair of large intracranial saccular aneurysms

Among 302 patients with cerebral aneurysms admitted between 1981 and 1986, 63 had a large (45) or giant (18) aneurysm with a diameter of more than 12 mm and 24 mm, respectively. 24 of these 63 patients were admitted early after a subarachnoid haemorrhage (SAH) so as to allow surgical repair within 72 hours. Eight of them were inoperable for various reasons and could not undergo definitive surgical repair and died. 16 patients underwent craniotomy and clipping of the aneurysm. 77% of the patients in preoperative grades I-IV made a good recovery with no or minimal neurologic deficit. During the same period 84% of patients with small aneurysms made a good recovery. The present data indicate, that large aneurysms rupture with a similar incidence compared to small aneurysms; saccular large ruptured aneurysms can be operated upon early with similar results as small aneurysms. However, devastating initial bleeds and poor outcome occur more frequently in patients with ruptured giant than in patients with small aneurysms. Most of the patients with ruptured giant aneurysms are comatose on early admission and cannot be considered for early surgery. Their poor prognosis is further reduced by a high rebleeding rate.

Computerized tomography and prognosis in early aneurysm surgery

A study of computerized tomography (CT) scans was performed in a consecutive series of 100 patients with ruptured saccular cerebral aneurysms who were admitted, diagnosed, and operated on within 72 hours after subarachnoid hemorrhage (SAH) and treated with calcium antagonists. The aneurysms were in the anterior portion of the circle of Willis in 95% of patients and in the posterior portion in 5%; 12% had multiple aneurysms. Preoperative neurological grades according to Hunt and Hess were I to III in 74% of patients and IV or V in 26%. Subarachnoid hemorrhage as determined by CT scanning was minor in 20%, moderate in 43%, and severe in 37% of patients. All patients received intraoperative and postoperative administration of the calcium antagonist nimodipine. Three days postoperatively, SAH (as measured by CT) was significantly reduced in the majority of patients but was still moderate in 18%. In the postoperative course, 2% of patients developed delayed ischemic neurological symptoms due to vasospasm. In two additional patients, ischemic symptoms were transient and fully reversible. At the 6-month follow-up interval, a significant prognostic difference was found between two patient groups with different CT scan findings. Among the patients with SAH only, the rate of good outcome (no or minimal deficit) was 93% when the preoperative neurological Grade was I or II; but even with a Grade of III to V, there was a good outcome in 84% of patients. By contrast, in patients with additional intracerebral and/or intraventricular hemorrhage, the good-outcome rate was only 44%. From these data it is concluded that morphological preoperative CT findings are of prognostic value and may even be superior to clinical grading in predicting outcome.

Indications for surgical treatment of cerebellar haemorrhage and infarction

This report summarizes the outcome of 56 patients with cerebellar lesions of vascular origin, 40 patients with cerebellar infarction, and 16 with spontaneous cerebellar haemorrhage. All patients had computerized tomography: occlusive hydrocephalus was diagnosed in 75% of patients with cerebellar haemorrhage and in 23% with cerebellar infarction. Nine out of 10 patients survived after early surgical evacuation of the haematoma and 4 of them recovered completely. Two patients underwent only external ventricular drainage (EVD), one died after 2 days, and the other recovered with a moderate deficit. Three of 4 medically treated patients died within one week; all had developed occlusive hydrocephalus. The fourth medically treated patient recovered completely; consciousness had never deteriorated nor had occlusive hydrocephalus developed. Among 40 patients with cerebellar infarction, 13 developed progressive deterioration of consciousness; 7 of them underwent decompressive craniectomy of the posterior fossa and survived. One patient had only external ventricular drainage and died. Four out of the 5 medically treated patients died during the acute phase. From these observations and several reports in the literature, it is concluded that both cerebellar haemorrhage and infarction should be operated on as soon as progressive deterioration of consciousness develops. This occurs more frequently in patients with cerebellar haemorrhage than with cerebellar infarction. Individual decision-making in each case necessitates intensive neurosurgical observation.