Increased pulmonary relative volume

The autonomous, sustained production of AVP in the absence of known stimuli for its release is called SIADH. In this syndrome, plasma AVP concentrations are inappropriately increased relative to a low plasma osmolality and to a normal or increased plasma volume. SIADH may be the result of one of several factors production of vasopressin by a malignancy (such as a small cell carcinoma of the lung), the presence of acute and chronic diseases of the central nervous system, pulmonary disorders, or a side effect of certain drug therapies. In addition, as many as 10% of patients undergoing pituitary surgery have a transient SIADH approximately 8 to 9 days after surgery (when the patient is at home), which responds to water restriction (2 to 3 days) and resolves without recurrence. In SIADH, a primary excess of AVP, coupled with unrestricted fluid intake, promotes increased reabsorption of free water by the kidney. The result is a decreased urine volume and an increased urine sodium concentration and urine osmolality. As a consequence of water retention, these patients become modestly volume expanded. The increase in intravascular volume causes hemodilution accompanied by dilutional hyponatremia and a low plasma osmolality. Volume expan-... 

Based on investigators recommendations, the effects of increasing doses of HBOC-201 were assessed in two subsequent studies.After the induction of anesthesia, collection of 1 L of blood, and the infusion of 1 L of RL solution, 24 patients (12 in each study) were randomly assigned to receive, within 30 min, a 6.9- or 9.2-ml/kg dose of either HBOC-201 or 6% HES. (Patients infused with Hb received either 0.9 or 1.2gHb/kg, respectively.) Then, patients received an additional 500 ml of RL solution to maintain intravascular volume. As before, patient data relative to systemic and pulmonary arterial pressures and arterial and mixed venous blood gases were used to calculate... 

In persons with normal kidney function, sodium balance is maintained at a sodium intake of 120 to 150 mEq/day. The fractional excretion of sodium (FENa) is approximately 1% to 3%. Water balance is also maintained, with a normal range of urinary osmolality of 50 to 1200 mOsm/L. In patients with severe CKD (Stages 4 and 5), sodium balance is achieved, but results in a volume-expanded state. FENa may increase to as much as 10% to 20%, possibly due to increased concentrations of atrial natriuretic peptide. An osmotic diuresis occurs with an increase in FENa leading to obligatory water losses and impairment in the kidney s ability to dilute or concentrate urine (urinary osmolality is often fixed at that of plasma or approximately 300 mOsm/L). Nocturia is present relatively early in the course of CKD (Stage 3) secondary to the defect in urinary concentrating ability. Total renal sodium excretion decreases despite an increase in sodium excretion by remaining nephrons. Volume overload with pulmonary edema can result, but the most common manifestation of increased intravascular volume is systemic hypertension. ... 

The cardiac pump theory advocates that there is (direct) pressure on the ventricles. This is supported by indications that compression depth is related to output, that cardiac (or more specifically ventricular) deformation is related to stroke volume, that the duration of compression has no effect, and that an increased compression rate will increase flow [17]. In the original manuscripts, as well as over time, 1.5 to 2 in. (4 to 5 cm) has been maintained as standard. Forward flow of blood is assumed to be caused by competent atrioventricular valves and sufficient competence of the aortic and pulmonary valves to avoid regurgitation during CPR diastole. Implicitly, ventricular filling is essential and artificial systole must be sufficiently frequent to generate acceptable flow, as stroke volumes may be relatively small compared to the normal 60 to 100 ml per beat at ejection fractions of 40 to 75%. Mitral valve closure during CPR systole is deemed essential for the cardiac pump theory to work. 

---