The pathophysiology of carbon monoxide poisoning and acute respiratory failure in a sheep model with smoke inhalation injury

A smoke inhalation model was created in 22 adult male sheep with pine smoke inhalation through an endotracheal tube for 6 min. Arterial blood gases, HbCO, HbO2 and pulmonary compliance (Cdyn) were monitored, and the morphology of the tracheobronchial tree and pulmonary parenchyma were studied by light and electron microscopy. Severe carbon monoxide poisoning with fatal levels of HbCO (greater than 50 percent) was found at the end of smoke inhalation. Acute respiratory distress, progressive hypoxemia, decreased pulmonary compliance and increased P(A-a)O2 and Qs/QT occurred after injury. Tracheobronchial blockade by pseudomembrane cast, pulmonary edema, atelectasis and necrosis of pulmonary epithelia were demonstrated pathologically. The mechanisms of CO poisoning and ARF are discussed.

Effects of endothelin on porcine coronary arterial strips

Endothelin, a novel endothelium derived 21-residue vasoconstrictor peptide synthesized by Peninsula Laboratories, provoked a concentration-dependent contraction of porcine coronary arterial strips. EC50 value for endothelin was 14 +/- SD 4 nmol/L (n = 6), and significantly lower than the values for 5-hydroxytryptamine (5-HT, 0.28 +/- 0.07 mumol/L, n = 6) and 15-methyl-prostaglandin F2 alpha (15-methyl-PGF2 alpha, 4 +/- 3 mumol/L, n = 7). The maximal increase in tension caused by endothelin was 5.4 +/- 1.1 g, being much greater than that induced by 5-HT (3.7 +/- 0.8 g, P less than 0.05) and 15-methyl-PGF2 alpha (3.7 +/- 0.6 g, P less than 0.01). The changes in tension provoked by endothelin (2-20 nmol/L) were attenuated significantly after pretreated with tetrodotoxin (TTX, 30 mumol/L, P less than 0.05 or 0.01). The results suggest that endothelin is one of the most potent vasoconstrictive agents, and its action is partially related to voltage-sensitive Na+ channel in the cell membrane.

Effect of smoke inhalation injury on thromboxane levels and platelet counts

Thirteen goats with chronic lung lymph fistula suffering from smoke inhalation injury were studied for a 6-h period. All animals were found to have acute respiratory failure after injury, the arterial TXA2 (thromboxane A2) levels had increased by 5 min after injury, they peaked at 2 h, and then subsequently declined. Peripheral platelet counts decreased progressively within 2 h, then gradually recovered but were still lower than baseline values at 6 h after injury. EVLW (extravascular lung water), Q1 (lung lymph flow rate) and L/P (total lymph protein/plasma protein concentration), all increased and peaked at 2 h after injury. A negative linear correlation was observed between the TXA2 levels and the platelet counts. Furthermore, differences between the venous and arterial platelet counts were markedly increased. All these observations suggested that the increased TXA2 triggered the formation of platelet microaggregates which were then trapped in the microvasculatures of viscera such as the lung. This might be one of the causes of the decreased platelet counts in peripheral blood. Both TXA2 levels and platelet counts were closely correlated with EVLW, suggesting that TXA2 may indirectly cause the increased pulmonary microvascular permeability by promoting platelet aggregation and microaggregate formation in the pulmonary microvasculature. This may be one of the reasons for the developing pulmonary oedema in goats following smoke inhalation injury.

Prediction of retention indexes. I. Structure-retention index relationship on apolar columns

A simple method is reported for predicting the retention index (RI) of a chemical compound from the number of carbon and carbon equivalent atoms in the molecule, the RI increment for atom addition and the group retention factors (GRFs) for substituents and functional groups. Atoms other than carbon such as oxygen, nitrogen, sulfur, chlorine, bromine and iodine are assigned carbon atom equivalency of approximately 1, 1, 2, 2, 3 and 4, respectively and are counted for their contribution towards RI prediction. The GRFs of substituents and functional groups are derived from the RIs of reference compounds and series of homologues. Ring structures, ring fusion, ring connection, iso- and neo-carbons, chain branching and unsaturation are also assigned GRFs. The predicted RIs of a number of alicyclic, aliphatic and aromatic hydrocarbons, primary, secondary and tertiary alcohols, phenols, aliphatic amines, aromatic amines, heterocyclics, carboxylic acids, acid esters, aldehydes, ketones, and halogenated compounds, are found to be within +/- 3% of the observed values. The structure-retention index relationship thus developed is extremely useful in the tentative identification of radioactive side products formed in tritium labeling by radiation-induced methods.

Dynamic changes of lung lymph flow and the release of lysosomal enzyme from the lungs after severe steam inhalation injury in goats

Chronic lung lymph fistulae were produced in six goats according to Winn's and Stothert's methods with our modification to define the pathophysiology of pulmonary oedema after severe steam inhalation injury. Arterial blood gas, lung lymph flow (QLym), lymph/plasma total protein concentration ratio (L/P), and beta-glucuronidase (beta-G) in plasma and lung lymph were monitored for 24 h post-injury. The pathological changes in the lung tissues were also determined at the end of the study. It was found that directly after injury, QLym increased steadily to a peak value at 6 h, followed by declining values at 18 and 24 h. L/P decreased promptly during the 60 min after injury and then also steadily increased to a peak value at 4 h (P less than 0.05). A significant increase in plasma beta-G was only observed at 4 h post-burn. However, lung lymph beta-G activities and lymph beta-G transport increased immediately after injury, reaching a peak at 4 h (5 and 12 times above baseline values, respectively, P less than 0.01). Significant hypoxaemia and hypocapnia occurred at 2 h post-burn and deteriorated progressively throughout the study. There were obvious pulmonary interstitial and alveolar oedema microscopically. This study demonstrates that the increase in transvascular fluid and protein flux after steam inhalation injury is mainly due to increased pulmonary microvascular permeability. Nevertheless, a hydrostatic pressure effect can not be completely excluded, especially in the first hour post-burn. Lysosomal enzyme release is considered to be one of the important factors which damage lung microvascular elements and induce an increase in their permeability.

Complete chaos in a simple epidemiological model

A first-order difference equation which constitutes a simple model for a lethal parasite-host interaction is studied. Completing a study initiated by May and Anderson, the dynamics are shown to be completely chaotic.

Effect of intravenous infusion on development of pulmonary oedema after inhalation injury

Last year, after a systematic search of pathological and patho-physiological changes of inhalation injury in dogs, we recorded severe pulmonary oedema as early as 2 h postburn (the earliest monitoring time designed in experiment) on dogs inflicted with both body surface and severe respiratory burns without any fluid replacement during the whole course of experiment. In an analysis of cases admitted into our burn centre in the past ten years, we also found that there was no definite relationship between the incidence and severity of pulmonary oedema occurring in severe burn patients and the amount of fluid infused in the early burn phase. These facts led us to the following experiment designed to study the effect of intravenous infusion on development of pulmonary oedema after severe burns complicated with inhalation injuries.