Tentative Recommendation on Terminology and Definitions in Respiratory Physiology: Résumé of the Isott Consensus Session 1992

1 The use of small letters for the symbols “p” (partial pressure), “s” (saturation) and “c” (concentration) (e.g. pO2, sO2, cO2) follows recommendations of the IFCC and IUPAC [4]. This supports the use of contemporary word processing systems and mostly eliminates the need to use subscripts (except for chemical valencies: e.g. O2, CO2, H2CO3 etc.). The potential risk of misinterpretations and double meanings is reduced also (e.g. “cO2” [oxygen concentration] v.s. “CO2” [carbon dioxide] and “sO2” [oxygen saturation] v.s. “sO2” [sulfur dioxide]). 2 The symbol shall include the site of measurement or description, e.g. paO2 (arterial O2 partial pressure), svO2 (mixed venous oxygen saturation), o…

Sauerstofftransportverm�gen von Blutersatzfl�ssigkeiten im Vergleich mit anderen Infusionsl�sungen

Zur Untersuchung des Sauerstofftransportvermogens von Blutersatzflussigkeiten wurden die O2-Loslichkeitskoeffizienten (ml/ml atm) bei 37° C von 12 Volumenersatzmitteln bestimmt und mit den O2-Loslichkeitskoeffizienten verglichen, die fur 12 Losungen zur parenteralen Ernahrung, fur 4 Elektrolytlosungen und 5 Losungen zur Osmotherapie ermittelt wurden.

A New Method for Measuring the Oxygen Content in Microliter Samples of Gases and Liquids: The Oxygen Cuvette

Gas analytical processes for the determination of oxygen content or concentration are based partly on physical principles (e.g. mass spectrometry, gas chromatography, paramagnetic methods) and partly on chemical methods (e.g. gasometric, titrimetric, electrochemical or photometric methods).

The accuracy of calculated base excess in blood.

Most equations used for calculation of the base excess (BE, mmol/l) in human blood are based on the fundamental equation derived by Siggaard-Andersen and called the Van Slyke equation: BE = Z x [[cHCO3-(P) - C7.4 HCO3-(P)] + beta x (pH -7.4)]. In simple approximation, where Z is a constant which depends only on total hemoglobin concentration (cHb, g/dl) in blood, three equations were tested: the ones proposed by Siggaard-Andersen (SA), the National Committee for Clinical Laboratory Standards (NCCLS) or Zander (ZA). They differ only slightly in the solubility factor for carbon dioxide (alphaCO2, mmol/l x mmHg) and in the apparent pK(pK'), but more significantly in the plasma bicarbonate conc…

Pure oxygen ventilation during general anaesthesia does not result in increased postoperative respiratory morbidity but decreases surgical site infection. An observational clinical study

Background. Pure oxygen ventilation during anaesthesia is debatable, as it may lead to development of atelectasis. Rationale of the study was to demonstrate the harmlessness of ventilation with pure oxygen. Methods. This is a single-centre, one-department observational trial. Prospectively collected routine-data of 76,784 patients undergoing general, gynaecological, orthopaedic, and vascular surgery during 1995–2009 were retrospectively analysed. Postoperative hypoxia, unplanned ICU-admission, surgical site infection (SSI), postoperative nausea and vomiting (PONV), and hospital mortality were continuously recorded. During 1996 the anaesthetic ventilation for all patients was changed from 30…

Optimal Pre-Oxygenation: The Nasoral-System

The human body’s intra-and extrapulmonary O2 reserves, i.e. the oxygen stores of the functional residual capacity (FRC) and the blood, will be rapidly depleted during any kind of respiratory arrest (apnea). Application of oxygen prior to iatrogenic apnea (e.g. for endotracheal intubation procedures), therefore, commonly is discussed [e.g. Miller, 1990] as the proposed measure designed to achieve an increase in the human body’s oxygen stores sufficient to avoid hypoxemia. This prophylactic application of oxygen simply has become to be termed “pre-oxygenation”, regardless of the amount of increase in the O2 stores actually achieved. A myriad of different techniques and procedures are practica…

Myokardiale Mehrarbeit mit Abnahme des O 2 -Verbrauchs: Abschied von einer Illusion

Zwei Kammern f�r die Mikroskopie und Mikrophotometrie vitaler Zellen

Es werden zwei Kammern zur mikroskopischen Beobachtung und mikrophotometrischen Untersuchung von lebenden Zellen beschrieben. Mit ihrer Hilfe ist es moglich. Zellen ohne Schadigung mechanisch so zu stabilisiren, dass sie bis zu Stunden an derselben Stelle liegen bleiben. In der Einstromkammer liegen die Zellen in einlagiger Schicht zwischen einem Deckglas und einer licht- und gasdurchlassigen Folie, die durch Adhasion festgehalten wird. Der an die Folie angrenzende Raum kann mit gewunschten Gasgemischen durchstromt werden. In der Zweistromkammer liegen die Zellen zwischen zwei lichtdurchlassigen Folien, von denen die eine Gase, die andere auch Flussigkeiten und geloste Substanzen durchtrete…

The determination of haemoglobin as cyanhaemiglobin or as alkaline haematin D-575. Comparison of method-related errors.

In order to compare the accuracy of haemoglobin (Hb) determination methods, the commonly used cyanhaemiglobin (HiCN) method and the recently developed alkaline haematin D-575 (AHD) method (R. Zander, W. Lang & H. U. Wolf (1984) Clin. Chim. Acta 136, 83-93; H. U. Wolf, W. Lang & R. Zander (1984) Clin. Chim. Acta 136, 95-104) were tested with respect to method-related errors such as plasma, cell, and Hb errors. Both methods yield a series of more or less significant errors which generally lead to an overestimation of the Hb concentration in the order of 1%. However, in all three cases of plasma errors, i.e. normal plasma error, plasma error in lipaemic blood, and plasma error in bilirubinaemi…

Base Excess and Strong Ion Difference: Clinical Limitations Related to Inaccuracy

Physiological HEPES Buffer Proposed as a Calibrator for pH Measurement in Human Blood

Abstract N-(2-hydroxyethyl)-piperazine-N'-2-ethanesulfonic acid, known as HEPES buffer, with p K in the physiological range was studied for use as an alternative to conventional phosphate buffer for the calibration of pH in modern clinical analyzers. In different series of aqueous equimolar HEPES buffer, pH was measured at 37 °C with a capillary glass electrode standardized previously using phosphate, and variations due to changes in total HEPES buffer concentration (0.025 to 0.320 mol/l), and NaCl (0 to 0.250 mol/l) were monitored. For 0.05 equimolar HEPES buffer without NaCl, the pH of 7.362 ± 0.003 (n = 15) obtained coincided well with the reference pH (7.364) from the National Institute…

Experimentelle Untersuchungen zur Sauerstoffversorgung des Auges

Zur Untersuchung der O2-Versorgungsbedingungen des Cornea-Endothels und der Linse uber das Kammerwasser muste die O2-Loslichkeit im Kammerwasser sowie im Innern der Linse bestimmt werden. Die in der Literatur geauserte Vermutung, das der Glaskorper als ein potentielles O2-Depot aufgefast werden konne, bedurfte der Uberprufung. Die bei Temperaturen von 10–40° C fur das Kammerwasser, Linsenhomogenate, Glaskorper und Hyaluronsaure-Losungen gemessenen Bunsenschen O2-Loslichkeitskoeffizienten (ml O2/ml atm) erlauben folgende Schlusfolgerungen:

Clinical Use of Oxygen Stores: Pre-oxygenation and Apneic Oxygenation

During states of respiratory arrest the human oxygen stores may be used therapeutically, regardless of the origin, i.e. either prior to the routinely induced apnea for endotracheal intubation or as an emergency measure in any other case of apnea. The present considerations focus on the clinical use of the oxygen stores available, applying.

Prediction of dilutional acidosis based on the revised classical dilution concept for bicarbonate

Due to the controversy surrounding the term dilutional acidosis, the classical dilution concept for bicarbonate has been rigorously revised for the prediction of pH, actual bicarbonate concentration, and base excess. In the algorithms derived for buffer solutions, blood, and whole body (1-, 2-, and 3-fluid compartment), only bicarbonate is considered. On dilution at constant Pco2, the final concentration of bicarbonate is the sum in terms of pH, due to the following processes: dilution, formation from chemical reaction with the nonbicarbonate buffers phosphate, hemoglobin, and plasma proteins, and transfer from erythrocytes and interstitial fluid to plasma. At constant Pco2, the level of c…

Theoretical Basis Versus Clinical Practice of Oxygen Parameters of Blood

Under optimal conditions all oxygen parameters of human blood are defined at a theoretical basis, accepted and understood by the clinicians, measured correctly by instruments of different manufacturers and, therefore, leading to clear diagnoses for the patients.

Use of an inspiratory impedance threshold valve during chest compressions without assisted ventilation may result in hypoxaemia

Although the concept of intermittent airway occlusion with the inspiratory impedance threshold valve (ITV) is a well-recognised strategy for improving efficiency of cardiopulmonary resuscitation (CPR), little is known about possible pulmonary side effects.After a baseline chest CT-scan, 24 pigs with beating hearts undergoing apnoeic oxygenation received an injection of a contrast medium and were then assigned randomly to either active compression-decompression CPR with ITV (ACD ITV CPR), ACD CPR alone, or standard-CPR with ITV (standard-ITV CPR), or standard-CPR alone. After a maximum of 5 min of chest compressions or if oxygen saturation dropped below 70%, the experiment was stopped, haemo…

Der Verteilungsraum von physikalisch gelöstem Sauerstoff in wäßrigen Lösungen organischer Substanzen / The Distribution Space of Physically Dissolved Oxygen in Aqueous Solutions of Organic Substances

Abstract In order to evaluate the distribution of molecular oxygen in biological systems, the oxygen solubility (ml/ml atm) at 37 °C in aqueous solutions of thirty organic substances with different concentrations was measured by the classical Van Slyke principle. The oxygen solubility always (with the exception of hemoglobin) decreases exponentially with increasing concentration of the respective substance. In all cases this behavior is described highly significant by a simple empiric exponential function, when the substance concentration as well as the oxygen solubility of pure water is given. The influence of one substance on oxygen solubility contributes additively to the over-all solubi…

Photometric Determination of the O2 Status of Human Blood Using the Oxystat System: cO2 (mL/dL), sO2 (%), cHb (g/dL)

The O2 status of arterial human blood (Zander, 1990) can be completely described by a set of four parameters: cO2 (mL/dL), sO2 (%), cHb (g/dL) and pO2 (mm Hg).

Cellular Oxygen Concentration

At low oxygen levels the intracellular or intramitochondrial concentration of molecular oxygen together with the amount of reduced cytochrome oxydase determines the rate of oxygen utilization. Below the so-called “critical oxygen concentration”, i.e. the value, at which a drop in the rate of oxygen uptake has its first evidence, the kinetic is described by the oxygen affinity (Km) of the respiratory chain, i.e. the concentration value for half maximal rate of oxygen uptake.

Influence of intracellular convection on the oxygen release by human erythrocytes

There is general agreement today that intracellular diffusive transport of HbO2 and O2 limits the rate of oxygen uptake or release by the blood in the exchange vessels. Recent hemorheological results have shown that the mammalian erythrocyte exhibits fluidity as its most unique rheological property: it can be deformed continuously and rapidly, shear and normal stresses can be transmitted to the interior of the cell where systems of laminar flow are induced. These mechanical properties lead to the question whether or not intracellular convection does take place in the erythrocyte and to what extent it plays a part in gas exchange. A method was developed which subjects oxygen-saturated soluti…

Zur Interpretation des O2-Bindungskurvenverlaufes

Zur Klarung der Frage, in welchem Mase bestimmte Parameter die O2-Affinitat des Hamoglobins beeinflussen, wird der Verlauf von O2-Bindungskurven theoretisch untersucht. Dabei wird berucksichtigt, das in der konventionellen Darstellung der Bindungskurve (O2-Sattigung als Funktion des O2-Druckes) zwei Gleichgewichte enthalten sind: Das erstgenannte Gleichgewicht wird wesentlich von der Grose des Bunsenschen Loslichkeitskoeffizienten α bestimmt, der seinerseits parameterabhangig ist. Eine Prufung der Abhangigkeit des Loslichkeitskoeffizienten von verschiedenen Parametern (Temperatur, Salzkonzentration) unter Benutzung der bisher vorliegenden Literaturangaben fuhrt zu folgendem Ergebnis: Sogena…

Proposal for Using a Standardized Terminology on Oxygen Transport to Tissue

The aim of the present proposal is to recommend some definitions of important and frequently used terms in the field of oxygen transport to tissue. The latest glossary on this topic is dated 1973 and was published by the International Union of Physiological Sciences (J. Appl. Physiol. 34, 549 – 558, 1973). In the meantime, some of these definitions are either outdated or are used in another sense.

Corneal Oxygen Supply Conditions

Pronounced cornea hypoxia induces swelling and a loss of transparency. Hypoxia of longer duration causes necrosis, particularly of the corneal endothelium. These findings were observed after ligation of the cilial arteries and the arteria carotis interna, after reduction of oxygen tension on the anterior corneal surface as well as after prolonged wearing of ill-fitted contact lenses (11, 15, 18, 22, 23). Because the normal function of the corneal endothelium plays a central role in maintaining transparency, an insufficient endothelial oxygen supply can directly influence vision (3, 17).

Normal Values of Oxygen Concentration in Human Blood

Under physiological conditions, the oxygen supply as the product of O2-concentration (mlO2/dl; %(v/v)) and perfusion is influenced by many factors (cf. Fig. 1): perfusion on one hand, oxygen partial pressure (pO2; mmHg), haemoglobin (Hb) concentration (g/dl) and O2 binding power of Hb on the other hand. Under pathological conditions, oxygen supply disturbances are related to hypoxemia, i.e. reduction of O2-concentration in the blood. The differential diagnosis of hypoxemia includes normoxic, hypoxic and circulatoric disturbances of oxygen supply (cf. Fig. 1). Thus it is necessary to describe a NORMOXIC HYPOXEMIA (anemic or toxemic), a HYPOXIC HYPOXEMIA (decreased O2-concentration caused by …