Luis A. Cibils

Myometrial and cardiovascular responses to alterations in plasma epinephrine and norepinephrine

Abstract Plasma epinephrine and norepinephrine levels were determined when these hormones were separately infused into patients in labor. Norepinephrine caused increased incoordinate uterine activity and a pressor response. Epinephrine diminished uterine activity during spontaneous and oxytocin-induced labor. Increased tonus was noted in half the cases of spontaneous labor once the infusion was discontinued. The major cardiovascular response to epinephrine was depressor. When the infusion was discontinued, a rapid decrease in plasma hormone levels was seen and normal values were attained within 5 minutes. These plasma levels were correlated directly with uterine activity but not with the cardiovascular response which persisted for a longer period of time.

Effect of l-epinephrine infusion on uterine contractility and cardiovascular system

Abstract Nineteen normal, term, pregnant patients in spontaneous or oxytocin-induced prelabor were given continuous intravenous infusions of l-epinephrine at rates of 5, 10, and 20 μg per minute (the latter only in 3 cases during a short period of time) for periods ranging from 60 to 180 minutes. Continuous tracings of intrauterine pressure, femoral arterial pressure, and pulse rate were recorded simultaneously in a 4 channel Sanborn apparatus. Intermittent electrocardiograms were recorded before, during, and after the infusions. The cardiac output was estimated by the pulse-pressure method. Under these conditions, the following results were found:n 1. 1. The spontaneous or induced activity of the uterus is significantly decreased at the rates studied. The decrease in the intensity of the contractions is the factor mainly responsible, though a consistent and constant drop in the frequency was also found. The opposite effect was found in two spontaneous prelabors. 2. 2. A recovery of the activity starts after a certain period in all spontaneous and in most induced cases. 3. 3. A rebound of increased uterine activity superimposed upon a significant hypertonus was found in one half of the spontaneous cases, but in only 1 induced case, after the infusion was discontinued. Total recovery was recorded in the remaining cases. 4. 4. At the starting of the infusion there appears a short drop in the blood pressure followed by a recovery and rebound lasting about 10 minutes. A steady decrease follows, stabilizing at lower values than the control values. The pulse rate changes in “mirror image” form. 5. 5. The interruption of the infusion produces a very short period of increased hypotension. The hypotension produced during the infusion lasts for at least half an hour after it is discontinued. 6. 6. The hypotensive effect of the infusion is due to a peripheral vasodilatation and diminished peripheral resistance. 7. 7. The electrocardiographic changes found agree with those previously reported. 8. 8. The infusion rate at 20 μg per minute produced extrasystoles, hypertension, and physical discomfort.

Cerebrospinal fluid pressure in labor

Abstract 1. 1. The CSFP elevation in response to a uterine contraction is predictable and consistent. It is associated with an increase in central venous pressure, ABP, stroke volume, and cardiac output. 2. 2. The maternal circulatory system serves as “transducer” which readily transmits the pressure change to the CSFP even in the presence of sleep and total sensory blockade. 3. 3. Respiratory cycle changes in CSFP demonstrate the rapidity with which changes in intrathoracic venous pressure can be communicated to the central nervous system. The Valsalva maneuver produces an exaggerated respiratory response. 4. 4. This study does not support the theory that the injection of a spinal anesthetic should be delayed during a uterine contraction because of turbulence of the cerebrospinal fluid.

Electrolyte content and distribution in human myometrium. II. Childbearing age group.

Abstract Normal myometria from 75 patients in the reproductive age range were analysed for: total water, Na, K, Ca, Cl contents, and inulin space. The cases were arranged into five groups according to menstrual history and histologic stage of endometrium. From serum values of Na, K, Ca and Cl, myometrial water content, and inulin space; distribution and concentrations of ions were calculated. Under the stated conditions of investigation, the following conclusions are warranted:n 1. 1. About 80 per cent of myometrial weight is water. Its total amount and distribution are significantly influenced by the cyclic estrogen-progesterone relationship. 2. 2. Extracellular space, estimated by inulin space, contains 40 to 44 per cent of the tissue water. 3. 3. Sodium and potassium contents and concentrations have a significant negative correlation in different areas of the same uterus, in different uteri, and throughout the ovarian cycle. 4. 4. Chloride and sodium, total as well as concentration, change predictably in the same direction but not proportionally, while Cl and K intracellular concentrations have a negative correlation. 5. 5. Sodium and chloride appear to be intracellular ions in high concentrations. 6. 6. The calculated K diffusion potential is considerably higher than reported measured resting membrane potentials, indicating the possibility that the latter may be the resultant of the interaction of the several free intracellular ions.

EFFECT OF SPARTEINE SULFATE UPON UTERINE ACTIVITY IN HUMAN PREGNANCY.

Abstract Sparteine sulfate administered intramuscularly in doses of 150 mg. has a mildly oxytocic effect on uterine contractility. The effect is enhanced by repeated intramuscular administration or by the intravenous administration of the drug at 2.5 mg. per minute over a sufficiently long period of time. It does not tend to improve the coordination of a uterine contractility pattern where the uterine contractility pattern is incoordinate prior to its administration. Under certain conditions it may produce an increasingly uncoordinated pattern of uterine activity. In its duration of action, and in its effect upon uterine contractility, sparteine sulfate resembles the ergot preparations more than it resembles oxytocin preparations.

Management of the Rh-sensitized patient

Abstract A 3 year experience with an Rh Clinic and consultation service is reviewed. The values and potential hazards of amniocentesis and intrauterine transfusion are considered. Attention is given to the reasons for neonatal and intrauterine deaths, to racial differences, and to a philosophy of management for the Rh isoimmunized group of patients.

Electrolyte content and distribution in human myometrium

Abstract Normal myometria from 75 patients in the reproductive age range were analysed for: total water, Na, K, Ca, Cl contents, and inulin space. The cases were arranged into five groups according to menstrual history and histologic stage of endometrium. From serum values of Na, K, Ca and Cl, myometrial water content, and inulin space; distribution and concentrations of ions were calculated. Under the stated conditions of investigation, the following conclusions are warranted:n 1.1. About 80 per cent of myometrial weight is water. Its total amount and distribution are significantly influenced by the cyclic estrogen-progesterone relationship. 2.2. Extracellular space, estimated by inulin space, contains 40 to 44 per cent of the tissue water. 3.3. Sodium and potassium contents and concentrations have a significant negative correlation in different areas of the same uterus, in different uteri, and throughout the ovarian cycle. 4.4. Chloride and sodium, total as well as concentration, change predictably in the same direction but not proportionally, while Cl and K intracellular concentrations have a negative correlation. 5.5. Sodium and chloride appear to be intracellular ions in high concentrations. 6.6. The calculated K diffusion potential is considerably higher than reported measured resting membrane potentials, indicating the possibility that the latter may be the resultant of the interaction of the several free intracellular ions.

Oxygen tension in the intervillous space

Abstract 1. 1. The oxygen tension in the maternal intervillous space blood of 64 outpatients has been measured with the polarographic electrode. 2. 2. The mean value is 42.0 mm. Hg. 3. 3. When blood with a high oxygen tension (arterialized) was obtained during different phases of a uterine contraction there was a decrease in the oxygen tension at the apex of the contraction. 4. 4. The location of the needle tip when drawing blood from the uterus has been discussed.