A pocket calculator program for noninvasive assessment of cardiorespiratory function

A pocket calculator program is described which facilitates rapid evaluation of pulmonary function at rest and during exercise. It embodies the Fick Principle applied to carbon dioxide; mixed venous carbon dioxide tension is measured by rebreathing, obviating the need for central venous or pulmonary artery catheterisation. The program is in two parts, Gas Phase and Blood Phase, which may be used separately. The variables calculated include tidal volume, CO2 production, oxygen consumption, respiratory quotient, alveolar ventilation and dead space: tidal volume ratio (Gas Phase); bicarbonate concentration, base excess, veno-arterial CO2 content difference, cardiac output, mixed venous oxygen saturation and pulmonary venous admixture (Blood Phase). Use of the program enables these variables to be calculated rapidly and accurately. Accuracy is improved by the application of equations which correct for alveolar-to-blood tension differences, effects of differing hemoglobin concentrations, arterial oxygen saturations and acid-base abnormalities; these calculations are otherwise very lengthy, time consuming and prone to error. The program allows simple noninvasive measurements to be applied to patients with a wide variety of metabolic, cardiac and pulmonary abnormalities in rest and exercise.     

Interrelationships between blood pressure, blood gases and plasma acetate concentrations during conventional hemodialysis

To determine to what extent the intradialysis changes in blood pressure (BP) are related to the variations in blood gases and plasma acetate concentrations (plAc), 11 dialysed uremics were studied with measurement of plAc,pH, pCO2 and pO2 every 60' during a hemodialysis lasting 4 hrs. Dialysis resulted in significant decreases in the BP, pO2 and pCO2 and in significant increases in pH and plAc. Multiple regression analysis demonstrated that the delta % for the mean BP was closely related to plAc, pCO2 and delta-% of body weight (BW). Partial regression coefficient indicated the following rank order of correlation: plAc greater than pCO2 greater than or equal to delta-% BW greater than pO2 = O, thus demonstrating that the fall in blood pressure is related both to the increase in plAc and the decrease in pCO2. The physiological relevance of these relationships is discussed. The hypothesis is advanced that the pCO2 decrease during dialysis might contribute to the acetate-induced vascular instability.     

Enlarged acid-base and blood gas calculations by electronical data computing in the blood gas laboratory.

A rapid anaysis of parameters of the acid-base equilibrium and blood gases during open heart surgery and emergency therapy is absolutely necessary. Computing of the several parameters of the acid-base status by slide rules or nomograms is time consuming and can be shortened by computer applications. The central blood gas laboratory consists of a blood gas analyzer for PO2, PCO2 and pH, an electronic desktop calculator, a four color X-Y-plotter and two data lines to the cardiac surgery unit and to the intensive care unit. The time needed for computing and feedback of the parameters could be decreased to one quarter. In addition to numerical data printout, a graphical representation of the several parameters is possible on a X-Y-plotter and includes the Rahn-Fenn-O2-CO2-Diagram with venous admixture, ventilation perfusion ratio, alveolar dead space ventilation and the standard and actual oxygen dissociation curve as well as the pH/HCO3- Acid-Base nomogram. Furthermore, a computer diagnosis of the actual disturbances can be plotted.     

Measurement of peritoneal fluid pH in patients with non-serosal invasive gastric cancer

The accurate pH range of peritoneal fluid is clinically valuable for the evaluation of some pathological conditions of the body, however, it is not easy to measure in healthy individuals. The aim of this study was to measure; pH, pCO2, pO2, Na+, K++, Ca++, HCO3-, and O2 saturation of the peritoneal fluid in patients with non-serosal invasive gastric cancer. One hundred and thirty four patients (86 men and 48 women), ranging in age from 24 to 91 years were enrolled in this study. After opening the abdominal wall, the probe of a portable pH meter was placed in the peritoneal fluid in the subhepatic space. In addition, I collected the peritoneal fluid from the subhepatic space to measure, pH, pCO2, pO2, Na+, K++, Ca++, HCO3-, and O2 saturation using an autoanalyzer. The pHs of the peritoneal fluids tested has a mean of 7.73 (range 7.46 - 8.10), and the other parameters were pCO2, 22.81 mmHg; pO2, 136.49 mmHg; Na+, 146.57 mmol/L; K++, 4.80 mmol/L; Ca++, 0.89 mmol/L; HCO3-, 30.54 mmol/L, and O2 saturation, 99.74%. This study describes a practical method of measuring the pH of peritoneal fluid. The result obtained reflects the normal adult peritoneal pH value, which I propose as a reference value.     

Differentiation between diseases using a programmable hand-held calculator and Bayes'' theorem: Application to lower gastrointestinal tract disorders

A program is presented for the Hewlett-Packard HP-41C programmable pocket calculator that computes posterior probabilities of more than 200 diseases on the basis of Bayes' theorem. Data for specific applications are stored in ASCII files. The program and data are retained in the non-volatile memory of the calculator. An example of the application of the program to six lower gastrointestinal tract disorders is given using data from the literature.     

Estimation of ED50 or LD50 using a programmable pocket calculator

A program is developed for estimation of median effective dose (ED50 or LD50), using the hand-held programmable pocket calculator HP41CV. The well-known Finney's algorithm of probit analysis is used. Input of data is simple, but is restricted to a maximum of 15 groups. The program structure makes use of the technique of indirect addressing for storage, and statistical register manipulation for weighted regression. The ability of the calculator to give sufficiently precise results can be exploited in other similar situations.     

A pocket calculator program for non-invasive bedside assessment of cardiorespiratory function

A pocket calculator program has been written for the rapid bedside evaluation of cardiorespiratory function. The unique features of this program are that it makes use of recently available non-invasive techniques for measurement of arterial oxygen saturation and mixed venous P_CO2. This enables calculation of pulmonary venous admixture and mixed venous oxygen saturation without the need for central venous or pulmonary artery catheterization. If the ventilation and respired gas concentrations are also measured, cardiac output and alveolar ventilation can be expressed in litres per minute, and the dead space: tidal volume ratio calculated.     

Comparative labor economics of calculators and computers.

Labor costs of writing and using a program are discussed, and input-bound one-pass processes are identified as an application area, in which a simple linear model defines a break-even point between calculator and computer use. Exploratory leisure time use is pointed out as an added attraction of programmable pocket calculators.     

Differentiation between two diseases using a programmable hand-held calculator and Bayes'' theorem: Application to Crohn''s disease and ulcerative colitis

A short general program is presented for the Hewlett-Packard HP-41C programmable pocket calculator that calculates posterior probabilities of two diseases on the basis of frequencies of nosographic characteristics using Bayes' theorem. Extended memory and functions modules allow the storage of many data in an ASCII file.     

Bayesian diagnostic theory using a programmable pocket calculator

A programmable pocket calculator program has been written to serve as an aid in diagnosis. The program uses a Bayesian statistical algorithm to calculate the relative probability of two diagnostic alternatives. The ability to carry out Bayesian statistical calculations at the bedside should make the use of such techniques more attractive to clinical practitioners.     

Relationship between oxygen tension and subgingival bacterial flora in untreated human periodontal pockets

The predominance of anaerobic bacteria in subgingival plaque samples suggests that the pocket environment is anaerobic. In the present investigation, a small oxygen tension (pO2) electrode was inserted into the base of the pocket and the pO2 was recorded. In addition, the plaque in these pockets was examined culturally and microscopically. The oxygen tension at the bottom of 36 pockets (5 to 10 mm in depth) ranged from 5 to 27 mmHg (1 mmHg congruent to 133.3 Pa) with a mean value of 13.3 mmHg. Moderate pockets (5 and 6 mm) exhibited a mean pO2 of 15.7 mmHg, which was significantly higher than the 12.0 mmHg found in the deeper pockets. The deep pockets had higher percentages of spirochetes and Bacteroides intermedius, whereas the moderate pockets had elevated proportions of Actinomyces naeslundii and Streptococcus mutans. The sites with oxygen tensions equal to or less than 15 mmHg had significantly higher percentages of spirochetes, whereas the microaerophilic Capnocytophaga species were found in pockets with a pO2 greater than 15 mmHg. The presence of bleeding in the pocket was associated with higher proportions of B. intermedius, Capnocytophaga sp., and A. naeslundii. These pO2 readings of periodontal pockets indicated that there is a spectrum of pO2 values which seem to define, in a general way, the microbiological composition of the pocket.     

Corporeal blood gas changes according to duration of drug-induced prolonged erection.

The corporeal blood gas changes in accordance with the duration of the prolonged erection which developed after intracorporeal pharmacotherapy with papaverine and phentolamine were investigated in 62 impotence patients. The picture of the corporeal blood taken from 15 psychogenic impotence patients (a control group) at 10 minutes after intracavernous injection when they showed full erections was arterial but there was pCO2 rise and pH drop compared to femoral artery blood taken simultaneously. As the erection lasted longer, significant gas changes of the cavernous blood began to appear (p < 0.0001): increase in pCO2 and decrease in pO2 from 4 hours, decrease in pH from 5 hours, decrease in O2 saturation from 6 hours. Erections lasting for more than 16 hours showed significantly worse hypoxia (p < 0.05). Therefore, to prevent hypoxia and metabolic acidosis, drug-induced prolonged erection would be better decompressed before it lasts for more than 4 hours.     

Evaluation of the Paratrend Multi-Analyte Sensor for Potential Utilization in Long-Duration Automated Cell Culture Monitoring

BACKGROUND: Compact and automated sensors are desired for assessing the health of cell cultures in biotechnology experiments. While several single-analyte sensors exist to measure culture health, a multi-analyte sensor would simplify the cell culture system. One such multi-analyte sensor, the Paratrend 7 manufactured by Diametrics Medical, consists of three optical fibers for measuring pH, dissolved carbon dioxide (pCO(2)), dissolved oxygen (pO(2)), and a thermocouple to measure temperature. The sensor bundle was designed for intra-vascular measurements in clinical settings, and can be used in bioreactors operated both on the ground and in NASA's Space Shuttle and International Space Station (ISS) experiments. METHODS: A Paratrend 7 sensor was placed at the outlet of a bioreactor inoculated with BHK-21 (baby hamster kidney) cells. The pH, pCO(2), pO(2), and temperature data were transferred continuously to an external computer. Cell culture medium, manually extracted from the bioreactor through a sampling port, was also assayed using a bench top blood gas analyzer (BGA). RESULTS: Two Paratrend 7 sensors were used over a single cell culture experiment (64 days). When compared to the manually obtained BGA samples, the sensor had good agreement for pH, pCO(2), and pO(2) with bias (and precision) 0.005(0.024), 8.0 mmHg (4.4 mmHg), and 11 mmHg (17 mmHg), respectively for the first two sensors. A third Paratrend sensor (operated for 141 days) had similar agreement (0.02+/-0.15 for pH, -4+/-8 mm Hg for pCO(2), and 24+/-18 mmHg for pO(2)). CONCLUSION: The resulting biases and precisions are com- parable to Paratrend sensor clinical results. Although the pO(2) differences may be acceptable for clinically relevant measurement ranges, the O(2) sensor in this bundle may not be reliable enough for the ranges of pO(2) in these cell culture studies without periodic calibration.     

An improved procedure for accurate assays of factor VIII.

An improved one-stage method for accurate assays of factor VIII combines highly reproducible end points with elimination of temporal drift and of subjective factors involved in graphic analysis. Activated deficient plasma substrate (ADPS) is used as a single reagent for parallel tests. The assays can be performed manually or, with much greater precision, on an 8-channel coagulation meter of new design in which end points are recorded automatically and depend on an abrupt clearing of agitated cloudy suspensions. The coagulation time readings are reproducible to 0.5%. Factor VIII levels are read off a standard table or computed from a general equation which is readily programmable on a pocket calculator and is valid over a wide range of concentrations, including very low plasma levels.     

A pocket calculator program for the evaluation of the oxygen diffusion to perfusion ratio

A pocket calculator program has been written for the evaluation of the oxygen difusion to perfusion ratio (). It allows one to avoid the computational errors involved by approximating the oxygen dissociation curve through a straight line.     

Measurement of ventricular volume with a programmable calculator

A program written for the Texas Instrument TI-59 programmable calculator is presented which computes the ventricular volume by use of the method of area-length or Simpson's rule. Geometric data of single-plane silhouette, or biplane silhouettes, or computer-tomographically reconstructed cross-sections of the ventricle are required for the volume computation.     

Calculator programmed assistance in making cell cultures

Summary A calculator program and instructions are presented for facilitating the preparation of single cell suspensions to be used in cell culture systems. The program has been written for the Texas Instruments Inc. TI-59 programmable calculator with printer. The instructions provided are intended for the novice with no previous programming experience and only a basic understanding of the calculator operation. The program provides the appropriate volume and cell concentration of the inoculum cell suspension for a given set of culture parameters. It also provides options for culture initiation when the cell yield in the concentrated suspension is insufficient to satisfy the parameters selected.     

Fourier analysis of biological signals with a programmable calculator

A Fourier analysis program written for the Texas Instruments TI-59 programmable calculator is presented. The program determines the Fourier coefficients of any time varying periodic signal.     

Mathematical inference of blood gas data

Direct measurement of serum pH and the partial pressures of blood oxygen and carbon dioxide may be performed economically and accurately using specific electrode devices, and these measured values may easily be corrected for patient temperature. Oxyhemoglobin saturation, serum bicarbonate concentration, oxygen and carbon dioxide content, and arteriovenous differences may then be calculated if hemoglobin and hematocrit are known. Although the computational techniques have been available for some time, they have not been combined into a single, efficient procedure which is readily usable in clinical practice.

A suitable computer program was written and extensively validated. Calculated oxyhemoglobin saturations are virtually indistinguishable from those of the standard oxyhemoglobin dissociation curve. The calculated P₅₀ (7.4) is 26.4. Calculated values of carbon dioxide content compare favorably with those published in the literature, and oxygen content determinations correspond well to measurements by the standard Van Slyke technique (r = 0.978).

Input and output requirements of the computation procedure are minimal and entirely discrete in nature. Programmable desk top calculators, or utility time shared computer systems with inexpensive keyboard-printer terminals could therefore provide this service.     

TI-59 programmable calculator program for calculating predicted operative mortality in general surgery

A program for the TI-59 programmable calculator for calculating predicted postoperative mortality is presented. Input data are based on handy, clinical, non-invasive pre-operative and operative parameters retrieved mostly significant in this respect by former multivariate logistic regression analysis of a broad data-base; their relative weights are incorporated into the program data base as basic coefficients. Considerations employed in its usage are discussed, as well as possible future technical and/or environmental modifications.