A study of the acute and chronic respiratory pathophysiology of hemorrhagic shock

Resuscitation of canine hemorrhagic hypotension with large-volume isotonic crystalloid: impact on lung water, venous admixture, and systemic arterial oxygen saturation

The objective of this study was to test the hypothesis that after hemorrhagic hypotension, reinfusion of the shed blood with threefold that volume of lactated Ringer's (LR) solution will significantly increase lung water and venous admixture and hence decrease systemic arterial oxygen saturation. A prospective, randomized, fixed-volume hemorrhage laboratory study was performed at the Oklahoma University Health Sciences Center on 18 anesthetized mongrel dogs. After 40 mL/kg of blood were withdrawn through a femoral artery catheter, the dogs were randomized either to the control group (n = 9) that received a reinfusion of the shed blood, or to the LR treatment group (n = 9) that received an intravenous mixture of the shed blood with 120 mL/kg of LR. After fluid resuscitation, pulmonary artery occlusion pressure (PAOP) and cardiac output (CO) were significantly increased in the LR group compared with control animals (PAOP, 18.7 +/- 1.1 vs 13.4 +/- 2.9 mm Hg; CO, 8.14 +/- 1.08 vs 4.59 +/- 0.47 L/min; P < .05 each). However, lung water, venous admixture, and systemic arterial PO2 were similar between groups. In this fixed-volume hemorrhage model, hemodiluting the reinfused shed blood with threefold the volume of LR did not significantly influence lung water, venous admixture, or systemic arterial oxygen saturation.

Studies on the mechanism of pulmonary vascular responses to miliary pulmonary embolism

The nature and mechanisms of pulmonary vascular responses which follow miliary pulmonary embolism were examined in intact dogs in which the isolated left lower lobe was perfused at constant blood flow. Embolization of the lung with plastic microspheres increased total pulmonary vascular resistance, whereas, in contrast, vascular resistance of the isolated perfused left lower lobe which was protected from embolization was decreased. This vasodilation was prevented by chronic denervation of the lobe and by ganglionic blockade. Cervical vagotomy also blocked the response but atropine failed to alter the vasodilation. The response, which appeared to be reflex in origin and involve efferent sympathetic pathways, was prevented by beta-adrenergic receptor blockade produced by propranolol. Since the lobar vascular response to norepinephrine was significantly enhanced by propranolol, it was concluded that embolization of the lung evokes pulmonary vascular reflex vasodilation which is mediated over the sympathetic nervous system via a beta-adrenergic receptor mechanism.

"A spoonful of sugar" - trans-alveolar nutrition

In this initial study, it has been postulated that even the simple bronchial administration of isotonic glucose and insulin can maintain alveolar cell metabolism as measured by A.T.P. activity; further studies, using aerosolized glucose solutions, will test the validity of the hypothesis that alveolar metabolism can be maintained by the administration of substrate in aerosolized form by the alveolar route and will determine whether this form of substrate administration has clinical potential.

Pulmonary mechanics and diffusion after 'shock lung'

Pulmonary function studies performed in seven patients who had recovered from 'shock lung' showed a highly significant decrease of diffusing properties of the lung, a slight loss of lung recoil pressure, and a borderline increase of residual volume with normal vital capacity and total lung capacity. Pulmonary compliance was normal. The interpretation of these findings is discussed.