Analysis of behavioural and physiological parameters for the assessment of postoperative analgesic demand in newborns, infants and young children: a comprehensive report on seven consecutive studies.

Many different systems for the assessment of pain in newborns and infants have been tested for validity, rarely for reliability but never for sensitivity or specificity. We aimed to determine whether the assessment of an analgesic demand in the lower age group during the postoperative period is possible by observational methods only. In an repetitive and sequential prospective process for identifying observationable behaviour and measurable physiological parameters as indicators of a postoperative analgesic demand, 584 newborns, infants and young children were studied (7 prospective studies, 4238 observations). Twenty-six items were selected as suggested by current literature and for reasons of economy and practicability. The factor analyses resulted in a two-factorial solution with the behavioural items loading on one factor and the physiological parameters on the other (principal component analyses). The physiological parameters blood pressure, respiratory rate and heart rate were found to be unreliable and had no discriminant power to detect an analgesic demand during the postoperative period (discriminant analyses, ROC-curves). In newborns and infants, nine observational items were identified as equally selective, reliable, sensitive and specific to the assessment of postoperative analgesic demand, whereas in young children only five items could be identified (discriminant analyses, ROC-curves). For economic reasons, these five items (crying, facial expression, posture of the trunk, posture of the legs, motor restlessness) were chosen as the basis of an additional pain scale ranging from 0=no pain to 10=maximal (Children's and Infants' Postoperative Pain Scale, CHIPPS). Its internal consistency yielded values for Cronbachs' alpha with 0.92 for toddlers and 0.96 for infants. The coefficient for interrater reliability was 0.93. The scale was validated constructively by the intravenous administration of metamizol, tramadol, nalbuphine, piritramide and ketamine (repeated measures analysis of variance). The Toddler-Preschooler Postoperative Pain Scale and CHIPPS equally identified painfree situations or analgesic demand in 87.4%. In cases with definite pain, the score of CHIPPS was never below 4 points. Seventy-one toddlers gave verbal comments on their pain intensity: in 29 painfree situations the CHIPPS score was 3.0 and in 29 painful situations it was 5.7. The values for sensitivity and specificity of CHIPPS were calculated to be 0.92-0.96 and 0.74-0.95, respectively (discriminant analyses). We conclude that it is possible to determine postoperative analgesic demand in the low age group of children by using an observational system such as CHIPPS alone.

[Respiratory and circulatory parameters as indicators of the postoperative analgesic demand in newborns and infants]. / Atem- und Kreislaufparameter als Indikatoren des postoperativen Analgetikabedarfs bei Neugeborenen und Säuglingen.

AIM OF THE STUDY: Due to immature cognitive functions, infants are unable to communicate their pain perception verbally. To assess postoperative analgesic demand, the anaesthetist has to rely on observational techniques. Generally, pain expression is considered to be a multidimensional phenomenon consisting of physiological, motor-reflex and behavioural patterns. The majority of observational approaches to pain assessment in infants use the behavioural dimension only, regardless of the fact that pain perception might contribute substantially to the stress response. The aim of this study is to evaluate, whether sensitivity and specificity of a behavioural pain scale (CHIPPS [1]) can be improved by adding physiological measures, especially those representing the stress response. PATIENTS AND METHODS: 30 infants aged 0-12 months and scheduled for unilateral herniorrhaphy were studied prospectively. In addition to 9 behavioural items (crying, facial expression, wrinkling of the forehead, motoric restlessness; posture of fingers, arms, legs, toes and torso) the ratio of actual physiological measurements (heart rate, respiratory rate, blood pressure) and their respective preoperative baseline values were recorded by a single observer in 5 minutes intervals during the first hour after recovery from anaesthesia. Maximal efforts were made to achieve valid measures. Factor analysis was performed to determine the dimensionality of the complete item pool. For additional validity testing, receiver operating characteristic curves (ROC) were calculated using the independent opinion of an experienced clinician as an external criterion. Discriminant analysis was performed to assess the accuracy of a combined behavioural and physiological scale. RESULTS: The factor analysis resulted in two independent dimensions: behaviour and cardiocirculatory measurements. The strong intercorrelations of all behavioural items and the fact, that the affective pain experience is expressed by a specific mimic behaviour, suggest the behavioural dimension to be regarded as pain expression. Because of the strictly orthogonal structure of the factor system, the circulatory and the respiratory dimension lack any relationship to pain experience. In addition to these statistical reasons, considerations on practicability disprove blood pressure and respiratory rate as useful pain indicators: Whereas the observer never failed to obtain a behavioural score, only 60% of the blood pressure measures and 80% of the respiratory rates were valid. In contrast, heart rate counts were obtained in over 99% and thus have to be considered as the only practicable physiological measurement in the early postoperative period. Corresponding to the results of the factor analysis, ROC curves suggest that the ability of the heart rate alone to assess pain is not substantially better than a random process, whereas the behavioural scale performs well. In addition the heart rate failed to improve the accuracy of the behavioural scale as shown by the results of a discriminant analysis. CONCLUSIONS: Despite the multidimensional approach and the corresponding multivariate analyses, a unidimensional scale consisting of behavioural items was found to be a valid indicator of an postoperative analgesic demand. Due to the lack of diagnostic properties and difficulties to obtain sound values even under research conditions, physiological measurements like blood pressure, respiratory rate and heart rate are not suitable for the assessment of a postoperative analgesic demand in infants, neither for clinical nor for research purposes.

[Development of an observational scale for assessment of postoperative pain in infants]. / Entwicklung eines Fremdbeobach-tungsbogens zur Beurteilung des postoperativen Schmerzes bei Säuglingen.

In a prospective trial in 139 infants ASA classification I-II 13 observational items were scaled during the first postoperative hour (13 assessments). The items were drawn from the literature and chosen for economic purpose. Factor analyses (Principal component, Kaiser Criterion, Scree-test) were used for the elimination of useless items and for the identification of suitable ones. The discriminative properties of single items and different subsets of items to detect an analgetic demand were tested in discriminant analyses and variance analyses with repeated measurements. Due to insufficient variance four items had to be eliminated: "nasolabial folding", "colour of the face", "sweating of the head", and "muscle tone". The factor analysis if the remaining 9 items resulted in a one factorial solution. Neither the corrected item-scale-correlations nor the inter-item-correlations showed advantageous properties of single items compared with the others. For economic reasons two 5-item scales were chosen for further evaluation in regard to sensitivity, specify and validity. The items "crying", "facial expression", "positioning of the legs", "positioning of the trunc" and "motoric restlessness" built the Children's and Infants Postoperative Pain Scale (CHIPPS) whereas an Infants Postoperative Pain Scale (IPPS) contained the items "crying", "facial expression", "positioning of the arms", "positioning of the trunc" and "motoric restlessness". The latter five items had shown the highest factor loadings. The two systems had a high intern consistency with alpha > 0.90 (p < 0.01) with at least 73% explained variance. Inter-item-correlations and corrected item-scale-correlations showed no differences between the two scales. The discriminant analyses resulted in almost identic data for specify, sensitivity and predictive values of the IPPS compared with the CHIPPS. There was a significant interaction between repeated measurements and the supply of Piritramide and Ketamine, but not of Midazolam. Concurrent and constructive validation were positive for both systems, using administration of Piritramide as a criterion. For clinical purpose the CHIPPS should be preferred, because it has been proven to be valid in children up to 4 years of age and because controlled data on its sensitivity, specify, reliability and validity could already be presented.

In vitro effects of putative neurotransmitters on synaptic ribbon numbers and N-acetyltransferase activity in the rat pineal gland.

The pineal contains a large number of classical transmitters and neuropeptides. Some of these neurochemicals are involved in the regulation of serotonin N-acetyltransferase (NAT) activity and hence in melatonin synthesis. Synaptic ribbons present in the pineal gland also exhibit a numerical day/night rhythm parallel to that of NAT activity. There is scarcity of information regarding the regulation of synaptic ribbon (SR) numbers. In the present study, we have investigated in vitro effects of a number of classical neurotransmitters and neuropeptides. NAT activity was used to monitor melatonin synthesis under the experimental conditions used. Norepinephrine (NE), Delta sleep-inducing peptide (DSIP), vasoactive intestinal polypeptide (VIP), adenosine and N-acetyl-asp-glu (NAAG) significantly increased NAT activity in rat pineal. DSIP and VIP also increase the stimulatory effect of NE on NAT activity. These neurochemicals had no effect on SR numbers. Gamma aminobutyric acid (GABA), serotonin and taurine affected neither NAT activity nor SR. Somatostatin increased SR numbers significantly, without having any effect on NAT activity. The effect of somatostatin is regarded to be pharmacologic, since rather high dosages (10(-4) M) were required to obtain a significant effect. Although somatostatin is present in the pineal and may change rhythmically, the inconsistency of the day/night rhythmicity and the lack of such a rhythm in female rats and male gerbils speaks against an important physiological role of somatostatin in regulating SR numbers.

[Initial results of the reliability and validity of a German-language scale for the quantitative measurement of postoperative pain in young children]. / Erste Ergebnisse zur Zuverlässigkeit und Gültigkeit einer deutschspachigen Skala zur quantitativen Erfassung des postoperativen Schmerzes beim Kleinkind.

In a previous study it was proved impossible to evaluate the validity of a system modified according to McGrath et al. for measuring postoperative pain in children. Three reasons were postulated for this result. The analgesics used did not modulate the pain in such a manner that the statistical analysis was effective; or the postoperative pain had an acute onset or fluctuated and the regular observations did not allow detection of the pain peaks; or the system used did not measure pain. Therefore, a new and different approach was adopted to evaluate the reliability and validity of a scoring system for the measurement of postoperative pain in small children. MATERIAL. Sixty children classed as ASA I and II and aged between 1 and 5 years were randomly allocated to 2 groups: one group received Tramadol (0.5 mg/kg) after the induction of anesthesia and the other group received placebo. Premedication and anesthesia were standardized. All indications were accepted except for urgent operations and painful diseases. For 1 h after the operation the children were continuously observed by an experienced pediatric anesthetist who did not know what drugs had been given. Every 15 min and when the observer was convinced that the children were in pain and needed analgesics the following items were scaled: wakefulness, wake-up reaction, crying, facial expression, position of the trunk, position of the legs, muscle tone, making contact, verbal communication on being asked about pain, special defense against stimuli and consolability. The items were included in a factor analysis (principal components). The number of the factors was detected using the Scree test. The only items accepted as reliable were those that had a substantial load of at least 0.4 at each measurement. The reliability coefficient was computed with the split-half technique (odd-even). The validity was estimated with a multifactorial analysis of variance with repeated measurements. When the observer was convinced that any child was in pain, Metamizol (15 mg/kg) was administered. Significance was assumed at P less than 0.05. The study was accepted by the ethical committee of the Ruhr University, Bochum. RESULTS. A replication verified the results of the previous study: the factor analysis resulted in a one-factorial solution. Of the 8 items (wakefulness, wake-up reactions, crying, position of the trunk, position of the legs, verbal communications on being asked about pain, special defense against stimuli) only 4 had a sufficiently substantial load on all measurements (crying, facial expression, position of the trunk and position of the legs). (ABSTRACT TRUNCATED AT 400 WORDS)

[Effects of chemotherapy and radiotherapy of malignant testicular tumors on residual testicular tissue]. / Auswirkungen der Chemotherapie und Strahlentherapie von malignen Hodentumoren auf das verbliebene Hodengewebe.

By morphologic and morphometric investigations of the residual testis after treatment of testicular cancer the deleterious effect of chemo- and radiotherapy are estimated. Approximately 4-5 years after treatment the reversibility of spermatogenesis is better in patients chemotherapy than in patients after radiotherapy.

[Nalbuphine and piritramid in the postoperative period in young children. 2. External respiration]. / Nalbuphin und Piritramid in der postoperativen Phase beim Kleinkind. Teil 2. Aussere Atmung.

The use of opioid analgesics often seems to be necessary for postoperative analgesia in small children. There is a risk however, that interactions between anesthetics and the opioid analgesics may cause significant respiratory depression. There is no reliable information about the influence of nalbuphine and piritramide on respiration in small children. Therefore, the actions of nalbuphine and piritramide versus placebo on the respiratory patterns of 46 children in ASA groups I and II and aged between 1 and 4 years were tested in a randomized double blind trial. METHODS. Selection criteria were: no disturbed development, no signs or symptoms of neurological disease, uncomplicated operation, no pain at time of admission, no indication for urgent operation, written parental consent. Operations, premedication and anesthesia were standardized as mentioned in the comparison paper. Anesthesia was induced and maintained with oxygen in nitrous oxide and halothane (FiO2:0.3). Intubation was performed without the use of any relaxant. Postoperatively the ventilation was continued with the same FiO2 and with 0.5 vol% of halothane over a period of at least 20 min until spontaneous breathing was reestablished and stable ventilatory parameters were obtained. A single bolus injection of either nalbuphine or piritramide 0.1 mg/kg or a placebo was then given i.v.. The breathing parameters VT, VI, respiratory rate, maximal inspiratory flow and the inspiratory/expiratory time ratio were evaluated using the computer-assisted pneumotachometric device with hot wire anemometers (Büttner et al.). They were measured before and 2, 5, 10 and 15 min after the drugs were administered. Capillary blood-gas values were sampled before and 10 min after administration of the drug and again 5 min after extubation. Heart rate and blood pressure were recorded by means of a Dinamap monitor. Statistical analysis of the data was carried out by means of the chi 2-test or Fisher's exact test when appropriate. For the metric data analysis of variance was performed. A full factorial design was calculated with drugs and time after injection as factors and baseline values as a covariate. Multiple comparisons were performed using the Tukey test. The level of significance was set at P less than 0.05. Homogeneity was considered when p greater than 0.2. RESULTS. In spite of randomization the 3 groups could not be regarded as homogeneous for weight. In 4 of the 46 children apnea developed after drug administration and controlled ventilation was needed. These were all in the piritramide group. This result was significant against nalbuphine and placebo. There was no significant correlation between the apnea and any anamnestic, demographic or respiratory parameters. Since apnea and breathing constitute different qualities, a pooling of the apnea data and the non-apnea data within the piritramide group is not allowed...

[Nalbuphine and piritramid in the postoperative phase in young children. 1. General condition]. / Nalbuphin und Piritramid in der postoperativen Phase beim Kleinkind. Teil 1. Allgemeines Befinden.

The influence of piritramide and nalbuphine versus placebo on the postoperative comfort of 54 children of ASA-group I and II in the age between 1 and 4 years was tested in a randomized double blind trial using the comfort/discomfort scale according to Büttner et al. METHODS. Operations, premedication and anesthesia were standardized. The patients were premedicated with midazolam 0.5 mg/kg rectally and a subsequent i.m. injection of ketamine 2.0 mg/kg with atropine 0.01 mg/kg. Anesthesia was induced and maintained by inhalation of oxygen/nitrous oxide and halothane (FiO2 = 0.3). All children were intubated and ventilation was controlled during the operation. After the operation, while in steady-state anesthesia with 0.5 vol% halothane and during spontaneous respiration the children received either piritramide (n = 17) or nalbuphine (n = 20) at a dose of 0.1 mg/kg, or placebo (n = 17) i.v. Respiratory and circulatory parameters were recorded for 15 min before the end of anesthesia. At 5 min after halothane had been discontinued the first measurement of the children's behavior was started, with 4 subsequent measurements at fixed time intervals of 15 min. The measuring system included the following 6 scaled items: wake-up reaction, methodical defense against stimuli, crying, facial expression, posture of the torso, posture of the legs. In addition, the waking state was scored at the same time intervals as awake, arousable, or not arousable. During the 1-h observation period all children who seemed to feel uncomfortable received midazolam i.v. at a maximal dose of 2 mg. Up to 24 h the required supplemental analgesics were noted, as were episodes of psychomotor agitation and vomiting. Written consent was obtained from the ethical committee and the children's parents. The results were tested in a 2-factorial analysis of variance (treatment factor: drugs; within-subject factor; repeated measurements). RESULTS. The 3 groups were considered to be comparable in terms of age, body weight, kind and duration of operation and circulatory values. The use of supplementary analgesics showed a significant effect in the treatment factor and in the within-subject factor: during the 1-h observation period the placebo group received midazolam significantly more often (64.7%) than the piritramide group (5.9%) or the nalbuphine group (35%). During the following 7 h 29.4% of the children of the placebo group required supplementary analgesics (piritramide: 23.5%; nalbuphine: 20%). Subsequently up to the 24th postoperative hour there was no need for any analgesic in the placebo group, whereas 11.8% of the piritramide group and 15% of the nalbuphine group required analgesics.(ABSTRACT TRUNCATED AT 400 WORDS)

[Critical aspects of an outside evaluation of postoperative pain in infants. A placebo-controlled double-blind study of the question of the reliability and validity of the measurement system]. / Kritische Aspekte einer Fremdbeurteilung des postoperativen Schmerzes beim Kleinkind. Eine Placebo-kontrollierte Doppelblindstudie zu Fragen der Zuverlässigkeit und der Gültigkeit eines Messsystems.

Postoperative analgesia in infants and young children is a topic of growing interest in pediatric anesthesia. Two systems measuring postoperative pain in this group of patients have been offered recently: CHEOPS (Childrens Hospital of Eastern Ontario Pain Scale) by McGrath et al. and OPS (Objective Pain Scale) by Hannallah et al. and Broadman et al. [3, 7, 8]. Both systems are economical and not reactive, but their validity is not satisfying. The validity of CHEOPS is based on the statements of experienced nurses, using the method of convergent validation by an expert's assertion. Hannallah and Broadman et al. judged the validity of their objective pain scale for infants and young children by statements of juveniles between 13 and 18 years of age. McGrath et al. accepted the item of spontaneous verbal communication as useful in the CHEOPS, although no such verbal comment occurred in their study on interrater and inter-item correlations. The aim of the present study was to evaluate the statistical qualification of items for measurements of the intensity of postoperative pain in young children and to investigate some aspects of their validity. MATERIAL AND METHODS. The study was performed in 54 children of ASA groups I and II aged 29.2 +/- 10.7 months. They were included in the study if they were pain-free before the operation and had no signs and symptoms of neurologic disease. The following operations were accepted: herniorrhapy, orchidopexy, circumcision, and umbilical herniorrhaphy. Premedication and general anesthesia were standardized. The patients were premedicated with midazolam 0.5 mg/kg rectally and subsequent intramuscular injections of ketamine 2.0 mg/kg with atropine 0.01 mg/kg. Anesthesia was induced and maintained by inhalation of oxygen/nitrous oxide and halothane (FiO2 0.3). All children were intubated and ventilation was controlled during the operation. After the operation and under steady-state anesthesia with 0.5 vol.% halothane and spontaneous respiration, the children received either nalbuphine 0.1 mg/kg, piritramide 0.1 mg/kg, or placebo in a randomized and double-blind manner. Respiratory and circulatory parameters were recorded for 15 min before anesthesia was discontinued. Five minutes after halothane had been discontinued the first measurement of the childrens' behavior was started with four subsequent measurements at fixed time intervals of 15 min. The measuring system was based on the six items of CHEOPS complemented by five items related to the waking state because it was assumed that the waking state generally modulates the child's ability to demonstrate pain. The design of the study was accepted by the ethic committee with the provision that neither a sedative nor an analgesic drug should be withheld from any child if indicated. Therefore, all children who seemed to feel discomfort according to the subjective impression of the anesthetist received midazolam intraveneously to a maximal dose of 2 mg. All the behavioral data were included in a factor analysis (principal components)...

[Comparative histological studies of germinative tissue after chemotherapy or radiation therapy in patients with malignant testicular tumors]. / Vergleichende histologische Untersuchungen am germinativen Gewebe nach der Chemo- bzw. Strahlentherapie bei Patienten mit malignen Hodentumoren.

Described in this paper are morphological and morphometric alterations that occurred to the remaining testicles in patients who had undergone chemotherapy or radiotherapy for malignant testicular tumours, with findings, on average, being recorded 4.5 years after treatment. Qualitative histological investigations of testicular tissue exhibited differentiated characteristics, with radiotherapy resulting in significantly stronger phenomena. Epithelial height was clearly reduced in conjunction with increase in wall thickness, especially after radiotherapy. Tubular lumens, in the wake of radiotherapy, were more often filled with hyalin than after chemotherapy. Unambiguous evidence was produced to impairment of fertility in response to both chemotherapy and radiotherapy.

Biospecific adsorbents on the basis of chloroformate-activated bead cellulose.

Carbohydrate-derived polymers are activated by the chloroformate N-chlorocarbonyloxy-5-norbornene-2.3-dicarboximide (ClCOONB). The advantages of this activation method are presented. The application of bead cellulose as adsorbent for biomedical and biotechnological purposes is demonstrated. Examples for immunoglobulin purification, streptavidin isolation, and biotransformation of porcine insulin are given.

[Psychotrauma associated with ambulatory and inpatient surgery in infants. A prospective study]. / Das Psychotrauma ambulanter und stationärer operativer Eingriffe bei Kleinkindern. Eine prospektive Studie.

The presumed advantages of day-case surgery are often based on the argument that this kind of surgery induces less psychic harm in children than inpatient care. However, medical psychologists in particular increasingly prefer short-term hospitalization with rooming-in or daily visits by the mother. Neither opponents nor supporters of day-case surgery could produce valid findings from controlled and methodically valid studies of this subject. MATERIAL AND METHODS. A controlled, prospective study of the psychogenic effects of non-acute surgery under general anesthesia in children between 2 and 6 years of age was performed. The childrens' psychologic alterations were measured 6 and 12 weeks after the operation using a structured interview of the mother. Twenty-four children were treated by day-case surgery, 28 as inpatients. All children belonged to ASA groups I and II. The interviewer was "blind" to the indication, kind of surgery and duration of hospitalization. The mothers' answers concerning the postoperative behavior of their children were coded in terms of frequency of changes (seldom, unchanged, more frequent) or intensity (vigorous, unchanged, slight) in comparison to the time before operation. The data were compared to the anxiety of the children and mothers before premedication. The childrens' anxiety was measured using the scoring system of Büttner and Breitkopf; the mothers' anxiety was measured using a modified scoring system according to Groeger and Grosse-Aldenhövel. RESULTS. 1. There were no significant differences between the day-case and the stationary groups, in either preoperative anxiety assessments or postoperative psychological findings. 2. In comparison with the total number of possible psychologic effects, the number that really occurred was very small; only in 6 of 81 items did more than one-third of the mothers report any changes. 3. Most items were reported as minimal changes. Therefore, all items had to be analyzed using the method of analysis of factors (mean components, varimax rotation, Scree-test). Within 44.7% of extracted variance there were 2 factors involving behavior. Items applying to factor 1 included disturbed sleep and increased attachment of the child to the parents, indicating "emotional confusion" or "troublesome behavior." Factor 2 indicated a more flexible manner of playing and increased ability to concentrate.4+

[Significant CO2 retention in children after premedication with Dormicum and Thalamonal]. / Bedenkliche CO2-Retention bei Kindern nach Prämedikation mit Dormicum und Thalamonal.

Whereas in adults the use of Innovar for premedication has been abolished, the combination of midazolam and Innovar is still recommended for the premedication of children. This combination may lead to an additional depressive effect on respiration. A prospective, randomized study was performed to evaluate the risk of ventilatory depression. In 36 infants capillary blood gas values were measured pre- and postmedication with either rectal midazolam (0.4 mg/kg) and i.m. Innovar (0.04 ml/kg) or after oral chlorprothixene (2.0 mg/kg). After chlorprothixen the blood gas values did not change, whereas after the combination of midazolam and Innovar pCO2 rose significantly from 35.5 to 43.0 mmHg. In 7 of 22 cases pCO2 reached values above 45 mmHg. This difference compared to the chlorprothixene group was significant (p less than 0.05). The pH fell significantly from 7.42 to 7.36 in the combination group. Clinical signs of respiratory depression could not be observed in this group. The combination of midazolam with Innovar is therefore not useful for premedication in infants and young children.

A novel carbonochloridate for activation of supports containing hydroxyl groups.

The conditions for the introduction of active carbonate groups into supports containing hydroxyl groups by reaction with 5-norbornene-2.3-dicarboximido carbonochloridate are described. Up to 1.5 mmol carbonate groups/g dry Sepharose 4B could be bound. In the case of glycine the reaction of the activated supports with the amino groups takes place with a 10-fold higher rate than the hydrolysis of the carbonate groups, and high coupling yields can be reached. It is shown that the activated supports are well suitable for the preparation of carriers for affinity chromatography or the immobilization of enzymes.

Portable instrumentation for on - site analysis of toxic vapors

The center for Environmental Research at Argonne National Laboratory has developed a versatile toxic vapor analyzer. This instrument, the chemical Parameter Spectrometer (CPS-100), was designed to detect, identify, and monitor any one of 26 - compounds strored in the library, which itself may be update or expanded (perhaps to >50 compounds). Implementation of such an algorithm would effectively expanded the library size and would still provide the user with sufficient data (perhaps class identification of compounds) so as to assess many potential hazards on the spot.The reliability of such a algorithm for "hazard classification" has been evaluated and compared to the present algorithms which selectively identify unknow vapors.(AU)