Phenylephrine increases cardiac output by raising cardiac preload in patients with anesthesia induced hypotension.

Induction of general anesthesia frequently induces arterial hypotension, which is often treated with a vasopressor, such as phenylephrine. As a pure α-agonist, phenylephrine is conventionally considered to solely induce arterial vasoconstriction and thus increase cardiac afterload but not cardiac preload. In specific circumstances, however, phenylephrine may also contribute to an increase in venous return and thus cardiac output (CO). The aim of this study is to describe the initial time course of the effects of phenylephrine on various hemodynamic variables and to evaluate the ability of advanced hemodynamic monitoring to quantify these changes through different hemodynamic variables. In 24 patients, after induction of anesthesia, during the period before surgical stimulus, phenylephrine 2 µg kg-1 was administered when the MAP dropped below 80% of the awake state baseline value for > 3 min. The mean arterial blood pressure (MAP), heart rate (HR), end-tidal CO2 (EtCO2), central venous pressure (CVP), stroke volume (SV), CO, pulse pressure variation (PPV), stroke volume variation (SVV) and systemic vascular resistance (SVR) were recorded continuously. The values at the moment before administration of phenylephrine and 5(T5) and 10(T10) min thereafter were compared. After phenylephrine, the mean(SD) MAP, SV, CO, CVP and EtCO2 increased by 34(13) mmHg, 11(9) mL, 1.02(0.74) L min-1, 3(2.6) mmHg and 4.0(1.6) mmHg at T5 respectively, while both dynamic preload variables decreased: PPV dropped from 20% at baseline to 9% at T5 and to 13% at T10 and SVV from 19 to 11 and 14%, respectively. Initially, the increase in MAP was perfectly aligned with the increase in SVR, until 150 s after the initial increase in MAP, when both curves started to dissociate. The dissociation of the evolution of MAP and SVR, together with the changes in PPV, CVP, EtCO2 and CO indicate that in patients with anesthesia-induced hypotension, phenylephrine increases the CO by virtue of an increase in cardiac preload.

The pelvifemoral rhythm in cam-type femoroacetabular impingement.

BACKGROUND: There is growing evidence that femoroacetabular impingement is a potentially important risk factor for the development of early idiopathic osteoarthritis in the nondysplastic hip. Understanding of affected joint kinematics is a basic prerequisite in the evaluation of mechanical disorders in a clinical and research oriented setting. The aim of the present study was to compare pelvifemoral kinematics between subjects diagnosed with femoroacetabular impingement and healthy controls. METHODS: The authors collected motion data of the femur and pelvis on a total of 43 hips - 19 cam impingement hips and 24 healthy controls - using a validated electromagnetic tracking device. The pelvifemoral rhythm in supine position was defined during both active and passive hip flexion and statistically compared between both groups. FINDINGS: A significant increase in posterior pelvic rotation was observed during active hip flexion in the femoroacetabular impingement group compared with the control group (P<0.001). During passive hip flexion, however, posterior pelvic rotation between the impingement group and the controls did not differ significantly (P=0.628). INTERPRETATION: Posterior pelvic rotation during active high-end hip flexion is increased in femoroacetabular impingement, indicating the presence of an active compensational mechanism that decreases the extent of harmful joint conflict during high-flexion activities.

Vanishing tumour of the colon ascendens due to acquired type II C1-inhibitor deficiency.

We present a patient with recurrent bouts of angioedema of the lips, throat and extremities with a negative familial history for angioedema. Laboratory results confirmed an angioedema due to acquired C1-INH deficiency (or acquired angioedema, AAE). As AAE can result from underlying disease, further investigation toward malignancy was initiated. A CT-scan of the abdomen disclosed a circumferential tumour of the proximal segment of the colon ascendens which disappeared by the time an ileocolonoscopy was executed. Angioedema of the bowel has been widely reported in hereditary angioedema, whereas it is anecdotal in AAE.