Bicarbonate in Arteries Measured Preoperatively for Cadaveric Single-lung Transplantation is Related to Intraoperative Extra-Corporeal Membrane Oxygenation Use: A Retrospective Preliminary Study.

Background: There are no known predictors of extracorporeal membrane oxygenation (ECMO) induction for single lung transplantation. Objective: The purpose of the present study was to clarify the relationship between variables and ECMO requirements in single lung transplantation. Methods: This study included adult patients who underwent cadaveric single lung transplantation between 2010 and 2019. After general anesthesia, the transplanted lungs were ventilated in all cases. The analysis included 38 patients in the ECMO required (RQ) group and 12 patients in the ECMO non-required (FR) group. Comparisons were made between the two groups for data affecting ECMO implementation, and data that were significantly different were subjected to multivariate analysis. Results: Prior to anesthesia, the bicarbonate (HCO3-) value of the FR group was lower than that of the RQ group (24.6±2.7 vs. 29.7±5.3 mmol/L, p=0.005). Multivariate analysis showed that the cut-off bicarbonate value was 29.6. The area under the receiver operating characteristic curve (AUROC) of the model was 0.869 (R2: 0.331), with a sensitivity of 79% and a specificity of 88%. The odds ratio was 1.63 for every unit increase in the bicarbonate value (95%CI: 1.11-2.39, p<0.001). Further, the FR group had higher arterial blood pressure (mean: 79.0±11.5 vs. 68.9±8.3 mmHg, p=0.030), less blood loss (432±385 vs. 1,623±1,997 g, p<0.001), shorter operation time (417±44 vs. 543±111 min, p<0.001), and shorter ICU stay (11±9 vs. 25±38 days, p=0.039). Conclusion: Preoperative evaluation of bicarbonate could predict the need for ECMO for single lung transplantation.

Heterotopic pregnancy diagnosed before the onset of severe symptoms: case report.

BACKGROUND: A heterotopic pregnancy (HP) is an extremely rare disease that represents the simultaneous occurrence of two or more implantation sites in the uterus and extrauterus. Early diagnosis of HP is difficult because of the presence of an intrauterine pregnancy (IUP). In most cases, a precise diagnosis was made after symptoms develop through the rupture or bleeding of the ectopic pregnancy (EP). The authors present a case that was successfully diagnosed as an undemonstrative HP. CASE: A 24-year-old multiparous woman became pregnant after taking clomiphene citrate. At ten weeks of pregnancy, an ultrasonography revealed gestational sacs containing fetuses in the uterus and the right adnexal region, respectively. The patient was diagnosed as having a HP and an emergency right tubal resectomy was performed. The IUP progressed normally and the fetus was delivered at 37 weeks of pregnancy. DISCUSSION: Even if a gestational sac can be confirmed in the uterus, a careful ultrasonographic examination should always be considered to determine the presence of a concurrent extrauterine pregnancy.

Comparison of actual tidal volume in neonatal lung model volume control ventilation using three ventilators.

In neonates, small changes in tidal volumes (V(T)) may lead to complications. Previous studies have shown a significant difference between ventilator-measured tidal volume and tidal volume delivered (actual V(T)). We evaluated the accuracy of three different ventilators to deliver small V(T) during volume-controlled ventilation. We tested Servo 300, 840 ventilator and Evita 4 Neoflow ventilators with lung models simulating normal and injured neonatal lung compliance models. Gas volume delivered from the ventilator into the test circuit (V(TV)) and actual V(T) to the test lung were measured using Ventrak respiration monitors at set V(T) (30 ml). The gas volume increase of the breathing circuit was then calculated. Tidal volumes of the SV300 and PB840 in both lung models were similar to the set V(T) and the actual tidal volumes in the injured model (20.7 ml and 19.8 ml, respectively) were significantly less than that in the normal model (27.4 ml and 23.4 ml). PB840 with circuit compliance compensation could not improve the actual V(T). V(TV) of the EV4N in the normal and the injured models (37.8 ml and 46.6 ml) were markedly increased compared with set V(T), and actual V(T) were similar to set V(T) in the normal and injured model (30.2 ml and 31.9 ml, respectively). EV4N measuring V(T) close to the lung could match actual V(T) to almost the same value as the set V(T) however the gas volume of the breathing circuit was increased. If an accurate value for the patient's actual V(T) is needed, this V(T) must be measured by a sensor located between the Y-piece and the tracheal tube.

Cesarean section and primary pulmonary hypertension: the role of intravenous dexmedetomidine.

Primary pulmonary hypertension is a fatal disease that frequently becomes evident in pregnancy. The management of pregnant women with primary pulmonary hypertension poses a number of difficult problems, especially where regional anesthesia is considered to be contraindicated. A 30-year-old woman who developed primary pulmonary hypertension at 23 weeks of pregnancy was transferred to our hospital. Systolic pulmonary artery pressure and plasma brain natriuretic peptide levels were markedly elevated. Nitric oxide inhalation and prostacyclin prevented the progression of cardiac failure and reduced both plasma brain natriuretic peptide and pulmonary artery pressure. Cesarean section was performed at 32 weeks under general anesthesia. A combination of nitric oxide, prostacyclin, nitroglycerin, and dobutamine were administered during surgery. Intravenous dexmedetomidine was specifically used during emergence and recovery from anesthesia. This provided effective pain relief and hemodynamic stability. Throughout the clinical course, brain natriuretic peptide levels was monitored and used as an indicator of cardiac failure.

Experimental derivation of relative biological effectiveness of A-bomb neutrons in Hiroshima and Nagasaki and implications for risk assessment.

Epidemiological data on the health effects of A-bomb radiation in Hiroshima and Nagasaki provide the framework for setting limits for radiation risk and radiological protection. However, uncertainty remains in the equivalent dose, because it is generally believed that direct derivation of the relative biological effectiveness (RBE) of neutrons from the epidemiological data on the survivors is difficult. To solve this problem, an alternative approach has been taken. The RBE of polyenergetic neutrons was determined for chromosome aberration formation in human lymphocytes irradiated in vitro, compared with published data for tumor induction in experimental animals, and validated using epidemiological data from A-bomb survivors. The RBE of fission neutrons was dependent on dose but was independent of the energy spectrum. The same RBE regimen was observed for lymphocyte chromosome aberrations and tumors in mice and rats. Used as a weighting factor for A-bomb survivors, this RBE system was superior in eliminating the city difference in chromosome aberration frequencies and cancer mortality. The revision of the equivalent dose of A-bomb radiation using DS02 weighted by this RBE system reduces the cancer risk by a factor of 0.7 compared with the current estimates using DS86, with neutrons weighted by a constant RBE of 10.

Effective dose of A-bomb radiation in Hiroshima and Nagasaki as assessed by chromosomal effectiveness of spectrum energy photons and neutrons.

The effective dose of combined spectrum energy neutrons and high energy spectrum gamma-rays in A-bomb survivors in Hiroshima and Nagasaki has long been a matter of discussion. The reason is largely due to the paucity of biological data for high energy photons, particularly for those with an energy of tens of MeV. To circumvent this problem, a mathematical formalism was developed for the photon energy dependency of chromosomal effectiveness by reviewing a large number of data sets published in the literature on dicentric chromosome formation in human lymphocytes. The chromosomal effectiveness was expressed by a simple multiparametric function of photon energy, which made it possible to estimate the effective dose of spectrum energy photons and differential evaluation in the field of mixed neutron and gamma-ray exposure with an internal reference radiation. The effective dose of reactor-produced spectrum energy neutrons was insensitive to the fine structure of the energy distribution and was accessible by a generalized formula applicable to the A-bomb neutrons. Energy spectra of all sources of A-bomb gamma-rays at different tissue depths were simulated by a Monte Carlo calculation applied on an ICRU sphere. Using kerma-weighted chromosomal effectiveness of A-bomb spectrum energy photons, the effective dose of A-bomb neutrons was determined, where the relative biological effectiveness (RBE) of neutrons was expressed by a dose-dependent variable RBE, RBE(gamma, D (n)), against A-bomb gamma-rays as an internal reference radiation. When the newly estimated variable RBE(gamma, D (n)) was applied to the chromosome data of A-bomb survivors in Hiroshima and Nagasaki, the city difference was completely eliminated. The revised effective dose was about 35% larger in Hiroshima, 19% larger in Nagasaki and 26% larger for the combined cohort compared with that based on a constant RBE of 10. Since the differences are significantly large, the proposed effective dose might have an impact on the magnitude of the risk estimates deduced from the A-bomb survivor cohort.

A case of gain-of-function mutation in calcium-sensing receptor: supplemental hydration is required for renal protection.

AIMS: The calcium-sensing receptor (CaSR) regulates the extracellular calcium level, mainly by controlling parathyroid hormon secretion and renal calcium reabsorption. In gain-of-function CaSR mutations, the genetic abnormalities increase CaSR activity leading to the development of such clinical manifestations as hypercalciuric hypocalcemia and hypoparathyroidism. We report a Japanese case of CaSR gain-of-function mutation and represent a therapeutic intervention based on the functional characteristics of CaSR in renal tubule. METHODS AND RESULTS (CASE): DNA sequence analysis revealed a heterozygous G to T mutation identified in a 12-year-old Japanese girl presenting with sporadic onset of hypercalciuric hypocalcemia and hypoparathyroidism. The mutation is located in the N-terminal extracellular domain of the CaSR gene, one of the most important parts for the three-dimensional construction of the receptor, resulting in the substitution of phenylalanine for cysteine at amino acid 131 (C131F) in exon 3. Based on the diagnosis of the gain-of-function mutation in the CaSR, oral hydrochlorothiazide administration and supplemental hydration were started in addition to calcium supplementation. The combination therapy of thiazide and supplemental hydration markedly reduced both renal calcium excretion and urinary calcium concentration from 0.4-0.7 to less than 0.1 mg/mg (urinary calcium/creatinine ratio) and from 10-15 to 3-5 mg/dl (urinary calcium concentration), respectively. This therapy stopped the progression of renal calcification during the follow-up period. CONCLUSION: Supplemental hydration should be considered essential for the following reasons: (1) calcium supplementation activates the CaSR in the kidney and suppresses renal urinary concentrating ability, (2) the thiazide has a diuretic effect, (3) as calcium supplementation increases renal calcium excretion, the supplemental hydration decreases urinary calcium concentration by increasing urinary volume, thereby diminishing the risk of intratubular crystallization of calcium ion.

Wiener filter-magnetoencephalography of visual cortical activity.

This paper reports a revised Wiener filter to resolve the inverse problem for magnetoencephalograms (MEGs) according to the structural and functional constraints based on magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI). Wiener filter-MEG imaging for half field stimulation with the chromatic stimulus resolved fast, slow and late responses in V1, V4 and the inferotemporal cortex, respectively. The time courses of these responses were roughly comparable with those reported by unit recording studies of the corresponding monkey visual cortical areas. Wiener filter-MEG imaging had comparable spatial resolution and better signal to noise ratio than fMRI. The background noise was robust in fMRI responses, but became virtually eliminated in Wiener filter responses. Wiener filter-MEG imaging with upper and lower quadrant field stimulation demonstrated V1 responses differentially distributed respectively in the lower and upper banks of the calcarine sulcus. These results demonstrate that responses in two cortical areas facing close to each other can be resolved by Wiener filter-MEG. The present method provides a way to image brain activities with millisecond- and millimeter-order spatiotemporal resolution.

Comparison between tube compensation and pressure support ventilation techniques on respiratory mechanics.

In the intubated patient, the presence of an endotracheal tube increases the work of breathing during spontaneous breathing. The tube compensation technique was developed as a new ventilator mode that can compensate for that additional the work of breathing. We investigated the respiratory parameters during the pressure support ventilation 0, 5, 10 cmH2O and tube compensation 100% modes of the Puritan Bennett 840 ventilator in ten postoperative patients who had undergone radical surgery for oesophageal cancer. Measurements were performed just before extubation. The tidal volume, respiratory rate and other respiratory parameters were measured with a Ventrak respiratory monitor, and the duty ratio, mean inspiratory flow, and rapid shallow breathing index were calculated. In particular, we performed a comparison between pressure support ventilation 5 cmH2O and tube compensation 100%, because pressure support ventilation 5 cmH2O is the usual ventilating mode before the extubation in our intensive care unit. The tidal volume of pressure support ventilation 10 cmH2O was significantly larger and the respiratory rate was significantly lower than the other three modes. There was no significant difference in the minute volume, tidal volume, and respiratory rate between pressure support ventilation 5 cmH2O and tube compensation 100%. The duty ratio of pressure support ventilation 10 cmH2O was significantly smaller than the other three modes. There was no significant difference in the duty ratio and rapid shallow breathing index between pressure support ventilation 5 cmH2O and tube compensation 100%. It was concluded that the assist levels of pressure support ventilation 5 cmH2O and tube compensation 100% were almost equal for clinical purposes.

Flexible computation of shape symmetries within the maximal disk paradigm.

Shape symmetries, like medial axes , contain a wealth of information useful in engineering and many different models for symmetry computation have been proposed. We present the hybrid symmetry transform (HST) as a compactly reformulated version of the maximal disk methods. HST is inspired by shunting inhibition networks and general concepts in wave dynamics. Through adjusting a shunting coefficient, the strength of adherence to the maximal disk paradigm becomes tunable. Each image location is scanned with a set of concentric rings which are then combined via weighted (shunting) summation, as opposed to the winner-takes-all approach in strict maximal disk methods. The new model is simple yet operates flexibly to compute maximal disk symmetries in a variety of conditions, interpreted as different wave propagation modes.

Case of radiation-induced esophageal ulcer worsened after endoscopic biopsy.

Esophageal ulcer is one of the most important late complications of the esophagus treated with radiation therapy, especially with intraluminal brachytherapy. We encountered a patient with esophageal cancer treated with external radiation therapy and intraluminal brachytherapy, who developed radiation ulcer and who had severe dysphagia soon after endoscopic biopsy of the ulcer edge. A 55-year-old man was diagnosed as esophageal cancer without symptoms. He received 60 Gy/30 Fr of external radiation therapy and 12 Gy/3 Fr of intraluminal brachytherapy at a point of 5 mm in depth from the mucosa surface. He developed an asymptomatic esophageal ulcer 13 months after treatment, and endoscopic biopsy was obtained from the edge of the ulcer. Thereafter, swallowing difficulties appeared, and endoscopy revealed severe esophageal stenosis and a deep ulcer. A possibility that the biopsy contributed to worsening the ulcer can be considered. Except for cases where relapse is apparent, endoscopic biopsy is considered to be avoided.

A VEP study on visual processing of figural geometry.

The possibility of a link between medial axes (hereafter called symmetries) and figure salience has recently been proposed [Vision Res. 38 (1998) 2323; Vision Res. 38 (1998) 2429]. In this paper we investigated the characteristics of transient visual evoked potentials (VEPs) associated with stimulus figures designed to have different symmetries. Significant trends were observed for VEP components N1 (160-190 ms) and P2 (220-250 ms). N1 and P2 had shorter peak latencies for stimuli with greater symmetry peak amplitudes.

Differences in respiratory parameters during continuous positive airway pressure and pressure support ventilation in infants and children.

The extubation criteria of pressure support ventilation (PSV) in infants and children were not yet established. We studied the differences in respiratory parameters during continuous positive airway pressure (CPAP) using a constant flow type ventilator and PSV using a demand valve type ventilator. Nineteen children (1.9+/-2.9 years old) who were ready to extubate were studied. All patients had recovered from their respiratory failure and had finished the weaning process of the ventilatory support. They were scheduled for extubation on the next day when their ventilatory mode had attained to a PSV of 3 cmH2O with a positive end-expiratory pressure (PEEP) of 3 cmH2O. On the extubation day, tidal volume (TV) and respiratory frequency (RR) were measured with a respiratory monitor at two modes (CPAP of 3 cmH2O and PSV), and the duty ratio (DR) and mean inspiratory flow (MF) were calculated. The sequence of the ventilatory mode was random. No case required reintubation. TV was 61.6+/-54.9 during CPAP and 67.7+/-61.4 ml during PSV, and RR was 38.5+/-10.6 and 37.1+/-8.8 beats/min., respectively. DR was 0.382+/-0.067 and 0.359+/-0.085, and MF was 96.6+/-78.3 and 101.0+/-69.0 ml/sec., respectively. The measured parameters and calculated values showed no significant difference between CPAP and PSV. It was found that the respiratory parameters were almost the same with CPAP and PSV immediately before the extubation, and the previous extubation criteria of CPAP can be used.

Clinical significance of serum pulmonary surfactant proteins a and d for the early detection of radiation pneumonitis.

PURPOSE: Radiation pneumonitis (RP) is one of the most serious complications for patients who receive thoracic irradiation. To avoid this, early diagnosis of radiation pneumonitis is extremely important. The purpose of the present study is to investigate whether serum pulmonary surfactant proteins A and D (SP-A and SP-D, respectively) could be useful markers for RP. METHODS AND MATERIALS: Eighty-six patients (lung cancer: 42 [primary: 39, metastatic: 3], breast cancer: 23, esophageal cancer: 21) who underwent radiation therapy were prospectively studied. Radiation doses ranged from 30-76 Gy (median, 58 Gy). Serum SP-A and SP-D levels were evaluated sequentially by a sandwich enzyme-linked immunosorbent assay (ELISA) method before, during, and throughout the follow-up period until the development of symptomatic RP or until one year after completion of radiotherapy. Specificity of the ELISA results was confirmed by Western blot analysis. Patients symptomatic for RP were graded according to the Common Toxicity Criteria. RESULTS: RP occurred in 19 patients. Serum SP-D levels of patients with RP were sequentially higher than those in patients without RP. In the monitoring, serum SP-D levels at 50-60 Gy showed greater sensitivity and positive predictive values for RP detection (74% and 68%, respectively) than SP-A (26% and 21%, respectively). Western blot analysis showed that the development of RP was due to overproduction, but not proteolysis of surfactant proteins. CONCLUSION: We confirm that serum SP-A and SP-D monitoring is a practical and useful diagnostic method for the early detection of RP.

Hyperbaric oxygen therapy given 30 minutes after spinal cord ischemia attenuates selective motor neuron death in rabbits.

OBJECTIVE: Spinal cord ischemia sometimes causes paraplegia because the spinal motor neuron cells are vulnerable to ischemia. Although various protective remedies for spinal cord injury have been reported, there have been few established clinical methods. Although hyperbaric oxygen (HBO) has been used clinically as a treatment for ischemia, the reason for its effectiveness is still uncertain because sufficient experimental data are lacking. DESIGN: Prospective, randomized, controlled study. SETTING: Experimental animal research laboratory in a university research center. SUBJECTS: Twenty-three Japanese white rabbits, weighing 2-3 kg. INTERVENTIONS: A modified rabbit spinal cord ischemia model of infrarenal aortic occlusion for 15 mins was employed. Rabbits were randomly assigned to four groups; the rabbits in group A did not undergo ischemic insults (n = 5). The rabbits in groups B and C underwent ischemic insult for 15 mins, followed by 1 hr of HBO treatment at 3 atm absolute with 100% oxygen at 30 mins (n = 6) or 6 hrs (n = 7) after reperfusion, respectively. The rabbits in group D underwent ischemic insult for 15 mins without HBO treatment (n = 5). MEASUREMENTS AND MAIN RESULTS: We observed neurologic functions for 14 days. The sections of the spinal cords were stained with hematoxylin and eosin, and the number of spinal motor neurons in ventral region was counted by light microscopy. All rabbits in groups A and B could stand, whereas all rabbits in groups C and D showed irreversible paraplegia on days 2 and 14 after reperfusion. Spinal motor neurons in ventral gray matter in groups C and D decreased significantly compared with those in groups A and B. CONCLUSIONS: HBO therapy shortly after ischemic insult had protective effects against ischemic spinal cord damage. However, delayed treatment with HBO did not change the prognosis.

Evaluation of tube compensation in the Bennett 840 ventilator--a new ventilatory mode to support spontaneous breathing.

Respiratory care patients frequently require intubation with an endotracheal tube (ETT). Unfortunately, the ETT introduces a pressure drop (deltaPETT) that depends on the respiratory flow rate, thus increasing the work of breathing (WOB). Pressure support ventilation (PSV) cannot adequately compensate for this added WOB, because the degree of inspiratory assistance by PSV is fixed. Therefore, a technique called tube compensation (TC) has been developed to address deltaPETT. We examined the performance of TC and compared it with PSV of 5 cm H2O. The experimental system was constructed from a simulator, a test-lung, flow sensors, and a Bennett 840, and the respiratory parameters were studied. ETTs with IDs 6.5 and 8.0 mm were used. The quadratic approximation obtained for deltaPETT in the 6.5-mm ETT was 2.316 x flow + 7.910 x flow2, while that for the 8.0-mm ETT was 1.881 x flow + 3.353 x flow2. The maximum inspiratory flow (MIF) increased significantly with increasing TC, but tidal volume and inspiratory time did not show marked changes. The MIF for TC of 100% was larger than that for PSV of 5 cm H2O, when the 6.5-mm ID was used, but there was no significant difference between these modes when an ID of 8.0 mm was used. For both the 6.5 and 8.0-mm IDs, the PV loop corresponding to 100% TC was larger than that for PSV of 5 cm H2O. TC only compensated for the WOB caused by the ETT, whereas PSV compensated for the WOB caused by the ETT and the demand valve system. In clinical use, the differences between TC and PSV will demand attention.

Heading judgement from second-order motion.

We examined human heading judgement from second-order motion which was generated by random-dots with the contrast polarity determined randomly on each frame. It was found that human observers can judge heading fairly accurately from second-order motion when pure translation is simulated or when self-motion toward a ground plane with gaze rotation is simulated but they cannot when self-motion toward cloud-like random dots with gaze rotations is simulated. It is suggested that the human visual system cannot decompose the flow fields into rotational and translational components by using second-order motion information alone, but it can do in some ways from the flow field of the ground plane.

Combined therapy with hypothermia and anticytokine agents in influenza A encephalopathy.

Two children with influenza A-related encephalopathy were treated with a combination of mild hypothermia (deep body temperature of the forehead: 35 degrees C) and anticytokine agents (high-dose methylprednisolone and ulinastatin), while receiving amantadine. One of the cases exhibited acute necrotizing encephalopathy on computed tomography (CT). Although no severe complications occurred, correctable hypokalemia and hyperglycemia occurred in both cases. Both patients recovered without any neurological sequelae. Our therapeutic protocol appears to be effective for managing influenza A-related encephalopathy.

The patchwork engine: image segmentation from shape symmetries.

We propose blind segmentation of images into shape-related 'patches' based on pre-calculated local symmetries (Van Tonder, G.J. & Ejima, Y. (1999). (Forthcoming a) Flexible computation of shape symmetries. Submitted for publication) in shape boundary contours. First, lateral weights between all points in the boundary contour map are assigned analogous to Euclidean distance maps in watershed segmentation (Beucher, S. & Lantejoul, C. (1979). Use of watersheds in contour detection. Proceedings of the International Workshop on Image Processing, CCETT, Rennes, France.). Lateral weights are then used to: (1) extract local maxima in symmetries; (2) link maxima within locally enclosed boundary contours; and (3) reconstruct shape contours using symmetry maxima as 'seeds'. The new model overcomes weaknesses of watershed segmentation. The new model closes gaps in relatively more solid image contours, but it is fundamentally different from methods based on contour interpolation (Grossberg, S., Mingolla, E. & Todorovc, D. (1989). A neural network architecture for preattentive vision, IEEE Transactions on Biomedical Engineering 36, 65-84; Heitger, F. & von der Heydt, R. (1993). A computational model of neural contour processing: figure-ground segregation and illusory contours. Proceedings of the Fourth International Conference on Computer Vision, IEEE Computer Society Press, Washington D.C. (pp. 32-40)). Images are segmented into shape-relevant color-by-number-like patches which compare well to related methods (Gauch, J. & Pizer, M. (1993). The intensity axis of symmetry and its application to image segmentation, IEEE Transactions on Pattern Analysis and Machine Intelligence, 15 (8), 753-770; Ilg, W. & Ogniewicz, R. (1995). The application of Voronoi skeletons to perceptual grouping in line images, Proceedings of the 11th International Conference on Pattern Recognition, The Hague, The Netherlands, pp. 382-385; Zhu, S.C. & Yuille, A.L. (1996) FORMS: a flexible object recognition and modeling system, International Journal of Computer Vision, 20 (3), 187-212.). Two primitive operations, comparison and merging of patches, are proposed as drives for exposing more global shape contours from patches. We conclude that symmetry goes beyond abstract shape morphology: it can contribute to figure-ground segmentation in early vision and form part of primitive operations needed to create hypotheses of complex shape.

Method for recovery of heading from motion.

A new method for recovery of heading from motion is developed on the basis of Longuet-Higgins and Prazdny's algorithm [Proc. R. Soc. London Ser. B 208, 385 (1980)]. In the algorithm a radial virtual flow field is generated and the difference between the original velocity field and the virtual radial field is computed. The difference vectors, which are directed to the heading point in the projected plane, allow us to estimate the direction of heading. The simulations of the algorithm were performed, and it was shown that the method estimates the direction of heading accurately.