pulmonary vascular resistance


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resistance

 [re-zis´tans]
1. opposition, or counteracting force, as opposition of a conductor to passage of electricity or other energy or substance.
2. the natural ability of a normal organism to remain unaffected by noxious agents in its environment; see also immunity.
3. in psychology or psychiatry, conscious or unconscious defenses against change, preventing repressed material from coming into awareness; they can take such forms as forgetfulness, evasions, embarrassment, mental blocks, denial, anger, superficial talk, intellectualization, or intensification of symptoms. It occurs because the blocked association or understanding would be too threatening to face at this point in the therapy; identification of what point the resistance comes at can be an important indicator of the patient's unconscious patterns.
airway resistance the opposition of the tissues of the air passages to air flow: the mouth-to-alveoli pressure difference divided by the rate of air flow. Symbol RA or RAW.
androgen resistance resistance of target organs to the action of androgens, resulting in any of a spectrum of defects from a normal male phenotype in which men have normal genitalia but infertility to complete androgen resistance in which the individual has a female phenotype. Complete androgen resistance is an extreme form of male pseudohermaphroditism in which the individual is phenotypically female but is of XY chromosomal sex; there may be rudimentary uterus and tubes, but the gonads are typically testes, which may be abdominal or inguinal in position. Called also testicular feminization and testicular feminization syndrome. Incomplete androgen resistance is any of various forms less than the complete type, manifested by a male phenotype with various degrees of ambiguous genitalia such as hypospadias and a small vaginal pouch, a hooded phallus, or a bifid scrotum that may or may not contain gonads.
drug resistance the ability of a microorganism to withstand the effects of a drug that are lethal to most members of its species.
insulin resistance see insulin resistance.
multidrug resistance (multiple drug resistance) a phenomenon seen in some malignant cell lines: cells that have developed natural resistance to a single cytotoxic compound are also resistant to structurally unrelated chemotherapy agents. Called also cross-resistance.
peripheral resistance resistance to the passage of blood through the small blood vessels, especially the arterioles.
pulmonary vascular resistance the vascular resistance of the pulmonary circulation; the difference between the mean pulmonary arterial pressure and the left atrial filling pressure divided by the cardiac output. Called also total pulmonary vascular resistance.
total peripheral resistance the vascular resistance of the systemic circulation: the difference between the mean arterial pressure and central venous pressure divided by the cardiac output.
total pulmonary resistance (total pulmonary vascular resistance) pulmonary vascular resistance.
vascular resistance the opposition to blood flow in a vascular bed; the pressure drop across the bed divided by the blood flow, conventionally expressed in peripheral resistance units. Symbol R or R.

pulmonary vascular resistance (PVR)

the resistance in the pulmonary vascular bed against which the right ventricle must eject blood.

pul·mo·nar·y vas·cu·lar re·sis·tance

(pul'mŏ-nar-ē vas'kyū-lăr rĕ-zistăns)
The resistance to blood flow through the pulmonary circulation, which is largely influenced by the degree of tone or caliber of the pulmonary arteries and capillaries. Can be measured with the use of hemodynamic monitoring.
References in periodicals archive ?
Recent studies in primary pulmonary hypertension including pharmacodynamics observations on pulmonary vascular resistance.
Individuals with scleroderma-associated PAH and idiopathic PAH both demonstrate elevated pulmonary artery pressures, increased pulmonary vascular resistance, and subsequent reductions in pulmonary perfusion and cardiac output that result in dyspnea, exercise intolerance, inactivity, and deconditioning.
The results showed that the single sildenafil dose was safe, and after 60 minutes led to a significant drop in pulmonary vascular resistance, total pulmonary resistance, pulmonary artery pressure, and cardiac output.
This agent also has produced a decrease in pulmonary vascular resistance and an improvement in the six-minute walk test.
2) Right-heart catheterization allows pressures and cardiac output to be accurately measured, and pulmonary vascular resistance to be calculated.
Therefore, pulmonary vascular resistance is increased.
In this 61-patient study, the primary efficacy analysis demonstrated a statistically significant absolute change from baseline in pulmonary vascular resistance compared to placebo, and also demonstrated numerical improvement in 6-minute walk distance.
Pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP) increase, ultimately leading to hypertrophy and dilation of the right ventricle, which accompanies progressive aggravation of right-sided heart failure.
The factors causing pulmonary hypertension were identified: previously known level of free thyroxin, pulmonary vascular resistance, cardiac output; new factors identified in this study pretreatment period, age, systolic blood pressure.
Thus, chronic alveolar hypoxia induced vasoconstriction increases pulmonary vascular resistance leading to pulmonary hypertension and thus cor pulmonale.
The mean pulmonary artery pressure was 53mmHg (88/28/53) that was 50% of systemic pressures with Qp:Qs 3:1 and pulmonary vascular resistance was 3.
Although the observed vascular changes did not achieve statistical significance, they drew attention to the association of chronic bronchitis with (1) viral and bacterial infections and (2) increased pulmonary vascular resistance.

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