[Obstetric bleeding: an update]. / La hemorragia obstétrica. Actualización.

Massive bleeding in obstetrics still ranks among the most frequent causes of maternal morbidity and mortality worldwide. The most frequent type is primary postpartum hemorrhage, which is usually the result of an atonic uterus. The clinical priorities are to assure hemodynamic stability and to correct coagulation abnormalities. If pharmacologic treatment cannot achieve these goals, invasive methods such as interventional vascular radiology or artery ligation must be used. Hysterectomy is the last resort when the previous methods fail. For the best prognosis, in terms of preventing death, maintaining maternal fertility and minimizing morbidity, every maternity ward should have a well-defined multidisciplinary protocol that facilitates diagnosis and immediate treatment.

[Quantification of dehydration of soda lime in clinical circumstances]. / Cuantificación de la desecación de la cal sodada en circunstancias clínicas.

HYPOTHESIS AND OBJECTIVES: When the CO2 absorbents, soda lime and baralime, have lost their normal level of hydration, they may react with certain halogenated anesthetics to produce appreciable levels of carbon monoxide. The degree of absorbent desiccation has been considered the limiting factor for this phenomenon. This study quantifies the level of dehydration of lime produced under clinical conditions and the influence of several factors. MATERIAL AND METHOD: Desiccation was determined: 1) at set periods of time (3, 7 and 14 days) after clinical use of fresh soda lime in general anesthesia using a fresh gas flow (FGF) of 6 l/min, and 2) after gas had been crossing the continuous flow (CF) oxygen reservoir at 7 l/min for 17 and 65 hours. Two anesthetic systems were used: a) the Ohmeda Excel-210, in which the continuous FGF did not cross the reservoir and b) the Siemens Ventilator 710, in which the FGF did cross the reservoir. The experiments were repeated with three types of lime. RESULTS: The clinical use of lime for 3, 7 and 14 days caused different levels of desiccation, with decreases in hydration of up to 50% and 14 days. Nevertheless, water content was always over 5%, a level at which no reaction with halogenated agents takes place. After 17 and 65 hours of CF in the circuit where continuous FGF did not pass through the canister, the water content did not change. With the Siemens 710 circuit, in which the continuous FGF crossed the canister, the dehydration level was 1.2 +/- 0.3% after 17 hours and 0.7 +/- 0.3% after 65 hours, a level that can produce CO upon reaction between lime and halogenated gases. The type of lime used had little effect. CONCLUSIONS: Lime does not desiccate to levels able to produce CO in daily use, regardless of the FGF system used. The phenomenon of desiccation depends on two factors: 1) use of anesthetic equipment in which continuous FGF conditions require gas to pass through the canister, and 2) the maintenance of CF for a sufficient period of time.

[Monitoring of mechanical ventilation during IPPV: implications due to the intrapulmonary entrapment of gas. Study on a physical model of the lung]. / Monitorización de la mecánica ventilatoria durante IPPV: implicaciones debidas al atrapamiento intrapulmonar de gas. Estudio sobre modelo físico de pulmón.

This work was undertaken to determine the possible influence of gas trapping on the values of total respiratory system compliance and on the air flow resistance at the air ways obtained by conventional effects of positive telespiratory alveolar pressure (auto-PEEP) typical of gas trapping on ventilatory dynamics. This study has been carried out in a physical model of the lung. The results support the contention that in the above situation: 1) the total compliance of the respiratory system measured as the quotient between the current volume and the plateau pressure (C.DIN) shows lower values than those of the static compliance (C.EST), and 2) flow resistance at the air ways must be measured as the quotient between the time constant and the plateau pressure. It should not be measured as the quotient between the time constant and the static compliance since in that case the values would be lower than the real ones.

[Preoxygenation for anesthesia]. / Preoxigenación en anestesia.

Oxygenation, or rather denitrogenation, prior to apnea during anesthetic induction attempts to replace alveolar nitrogen with oxygen to achieve an intrapulmonary oxygen reserve that will allow apnea to be as prolonged as possible with the least possible desaturation. During apnea, the rate of arterial desaturation depends mainly on the volume of oxygen stored in the lung, on mixed venous oxygen saturation, and on the presence of intrapulmonary shunt. Together, these factors account for the higher rate of desaturation during apnea in children, obese individuals, postoperative patients, and pregnant women. Two approaches to preoxygenation have proven effective to date: ventilation with 100% oxygen at tidal volume for 3 minutes using a well-sealed face mask and the performance of 8 vital capacity maneuvers in 1 minute. The efficacy of preoxygenation can be assessed by expired oxygen fraction or by pulse oximetry. In a healthy adult, both methods described ensure sufficient oxygenation (pulse oximetry 90% to 95%) after a period of apnea lasting between 6 and 10 minutes.