The deposition of monodisperse aerosols in models of single lung airway bifurcations was studied. The particles, generated by spinning disk, were in the size range of 4.2--8.8 microns (density 1.3 X 10(3) kg . m-3). The model bifurcations were symmetrical, of physiological size, and based on established morphological data. The effects on percentage deposition (P) of flow rate (expressed as Reynolds' number. Re), particle diameter (d), tube diameter (D), and bifurcation angle (2 theta) were studied and a generalized expression for deposition based on these variables was obtained, viz., P = 11.04 X 10(5) Re (d/D)2.5sin3 theta. The applicability of this equation is discussed.

We describe three cases of electromechanical dissociation under anaesthesia that were unresponsive to doses of intravenous epinephrine given according to current Advanced Life Support guidelines, but which responded immediately to the intravenous administration of the pure alpha agonist, methoxamine. We suggest a possible mechanism to explain this finding and review the literature on vasopressor drugs used for cardiopulmonary resuscitation during electromechanical dissociation. An intravenous alpha agonist, such as methoxamine 20 mg, should be considered for any case of cardiac arrest secondary to electromechanical dissociation which is unresponsive to epinephrine given according to current guidelines.

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these data suggest that the small intestine may be a significant source of lactate and alanine for utilization by the liver. During fasting, intestinal glutamine oxidation to C02 and the subsequent production of alanine are not affected (3, 9) and so the intestine may be an important source of alanine. These studies, which identified significant aerobic small intestinal metabolism of glucose to lactate and the oxidation of glutamine to C02 (1-4), were done under anesthesia and with bowel manipulation. Anesthesia can alter blood substrate concentrations as well as the metabolism of substrates (3). Ether, for example, increases blood glucose and lactate concentrations (10). Anesthesia also can decrease cardiac output which would decrease mesenteric blood flow and intestinal perfusion. Surgical manipulation can alter intestinal metabolism and perfusion. Metabolic studies involving the fetal lamb exemplify the importance of chronic catheterization in contrast to acute catheterization (1 1).We set out to determine the effect of fasting on small intestinal metabolism and the resulting effect on portal venous blood substrate concentrations under physiologic conditions. We used a chronically catheterized rat model in which the portal vein and aorta remained patent for blood sampling. The portal venous and aortic blood concentrations of glucose, lactate, alanine, and glutamine were measured in the fasted and fed states. In the fasting state intraluminal substrates are unavailable to the intestine, so the portal venous to aortic blood concentration gradient reflects qualitatively the utilization or production of blood borne substrates by the intestine. MATERIALS AND METHODS Animals.All experiments were performed in vivo using adult Many low birth weight infants are nourished using parenteral male, albino, Sprague-Dawley rats (200-300 g body weight). methods. If the intestine is primarily an absorptive organ, this These animals were obtained from Simonsen Labs (Gilroy, CA) therapy may be appropriate. However, the small intestine per-and allowed free access to water and rat food. The adult rats forms several major metabolic functions including oxidation of were weighed and anesthetized with a 20 mg/kg ketamine inglucose to lactate under aerobic conditions (1-3), oxidation of jected intramuscularly followed by a 10 mg/kg pentobarbital glutamine to C02 (3,4), and conversion of lactate to alanine and injected intrapentoneally. Using aseptic technique, portal venous C02 after infusions of lactate (3). These important intestinal and aortic catheters were surgically placed as described previously metabolic functions release gluconeogenic precursors, alanine (12). After surgery, animals were weighed daily and the catheters and lactate, into the portal venous effluent which perfuses the were flushed with 0.35 ml of normal saline containing 500 U/ liver. Ramesy et al. (5) have reported elevated portal venous ml heparin and 2.5 mg/ml of ampicillin. concentrations of glucose, alanine, and lactate in fed rats. KatzThe effect offasting ...

Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of expiratory gas, one would predict that the time allowed for exhalation would have serious effects on cardiopulmonary function. To document these effects we lavaged the lungs of ten cats with 30 ml/kg of saline six times, then sampled arterial and venous blood while the animals were ventilated conventionally at 30 BPM and then with HFJV at 600 BPM, varying inspiratory/expiratory ratios (I/E) from 1:1 to 1:5. The animals breathed 100% O2 throughout the study, and the mean airway pressure was held constant for each animal when the I/E was varied during HFJV. Decreasing the I/E from 1:1 to 1:5 during HFJV resulted in an increase of arterial oxygen content (Cao2) from 11.3 +/- 1.2S E to 13.6 +/- 1.2 ml O2/100 ml blood (P less than 0.01), a decrease of PaCO2 from 43 +/- 6 to 27 +/- 4 mm Hg, and an increase of alveolar to arterial oxygen gradient from 351 +/- 49 to 377 +/- 49 mm Hg. The ratio of systemic blood flow to oxygen consumption (Q/VO2) was similar during conventional ventilation and with HFJV at I/E of 1:1 (18.9 +/- 3.7 vs 18.0 +/- 2.9) but decreased when I/E was reduced to 1:5 during HFJV (13.9 +/- 2.1). The ratio of the product of CaO2 and Q (systemic oxygen availability) to VO2 (SO2 T/VO2) remained unchanged during all modes of ventilation (1.75 +/- 0.15). The increase in CaO2 observed when I/E was reduced from 1:1 to 1:5 during HFJV was counterbalanced by a decrease in Q/VO2 such that SO2 T/VO2 remained relatively constant.