PubMed · 8882086
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J M Shneerson. 1996. Techniques in mechanical ventilation: principles and practice.. https://doi.org/10.1136/thx.51.7.756
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An entirely new type of blood gas analyser has made its way into the marketplace, to be used, for example, in emergency rooms, intensive care units, ambulances, and bedside with quarantined patients in infectious diseases units. The instruments reviewed here employ new miniaturised analysis circuitry, integrated into the cassette on which the blood sample is applied. These instruments are designed for use by care-givers without specific laboratory training. Four point-of-care blood gas analysers are tested: OPTI 1 (AVL), I-STAT (HP), IRMA (Infiniti) och ABL 70 (Radiometer).
We explored the ability of sodium nitroprusside to modify adhesive and cohesive function of platelets in flowing blood, under normoxic and hypoxic conditions. Aliquots of both untreated and sodium nitroprusside-treated blood were prepared for studies of: (1) platelet aggregation in plasma; (2) erythrocyte deformability; (3) platelet interaction with damaged subendothelium, by using a well-defined perfusion system; and (4) blood gasometry in the perfused samples. Results showed that sodium nitroprusside-treated blood always showed a totally inhibited arachidonic acid-induced platelet aggregation in plasma, as well as significantly increased erythrocyte deformability (0.44+/-0.09 up to 0.66+/-0.05; p<0.05). However, treatment with sodium nitroprusside did not modify the pattern of platelet interaction with subendothelium (percentage of contact, adhesion, thrombus, and covered surface) with respect to untreated blood, under any of the shear rates used (300, 800, and 1800 seconds(-1)), although it significantly reduced the height of thrombi (9.8+/-0.4 vs. 8.3+/-0.4 microm; p<0.05). Hypoxic conditions did not have a noticeable effect in modifying antiplatelet effects of sodium nitroprusside. Additionally, the presence of sodium nitroprusside impaired the normal oxygenation of the blood during perfusion. pO2 in control untreated samples rose from 40.3+/-5.0 mm Hg perfusions to 100.4+/-12.5 mm Hg but remained at 66.3+/-6.3 mm Hg in sodium nitroprusside-treated blood (p<0.05). Our results did not show a significant effect of sodium nitroprusside in the modulation of platelet interaction with subendothelium. The marginal reduction in the thrombi height could be related to rheological interference of increased erythrocyte deformability.
We set out to evaluate the impact of volume-targeted synchronized ventilation and conventional intermittent mandatory ventilation (IMV) on the early physiologic response to surfactant replacement therapy in neonates with respiratory distress syndrome (RDS). We hypothesized that volume-targeted, patient-triggered synchronized ventilation would stabilize minute ventilation at a lower respiratory rate than that seen during volume-targeted IMV, and that synchronization would improve oxygenation and decrease variation in measured tidal volume (V(t)). This was a prospective, randomized study of 30 hospitalized neonates with RDS. Infants were randomly assigned to volume-targeted ventilation using IMV (n = 10), synchronized IMV (SIMV; n = 10), or assist/control ventilation (A/C; n = 10) after meeting eligibility requirements and before initial surfactant treatment. Following measurements of arterial blood gases and cardiovascular and respiratory parameters, infants received surfactant. Infants were studied for 6 hr following surfactant treatment. Infants assigned to each mode of ventilation had similar birth weight, gestational age, and Apgar scores at birth, and similar oxygenation indices at randomization. Three patients were eliminated from final data analysis because of exclusionary conditions unknown at randomization. Oxygenation improved significantly following surfactant therapy in all groups by 1 hr after surfactant treatment (P < 0.05). No further improvements occurred with time. Total respiratory rate was lowest (P < 0.05) and variation in tidal volume (V(t)) was least in the A/C group (P < 0. 05). Minute ventilation (V(')(E)), delivered airway pressures, respiratory system mechanics, and hemodynamic parameters were similar in all groups. We conclude that volume-targeted A/C ventilation resulted in more consistent tidal volumes at lower total respiratory rates than IMV or SIMV. Oxygenation and lung mechanics were not altered by synchronization, possibly due to the volume-targeting strategy. Of the modes studied, A/C, a fully-synchronized mode, may be the most efficient method of mechanical ventilator support in neonates receiving surfactant for treatment of RDS.