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Biomedical subjects

J I Gerson

Publications and source records attributed to J I Gerson.

12 recordsLinked to original sources
PubMed1991

Serum levels of Hyskon during hysteroscopic procedures.

Hyskon hysteroscopy fluid is used with the hysteroscope as an aid in distending the uterine cavity and in visualizing its surfaces. We correlated the amount of Hyskon used during hysteroscopy with both the instillation pressures generated within the uterine cavity and with serum levels of Hyskon in 11 healthy subjects. Serum levels in excess of 1000 mg% were measured at 30 min when an amount of Hyskon greater than 300 mL was used. Intrauterine Hyskon absorption and/or injection during hysteroscopy were found even after volumes of Hyskon as small as 50-100 mL were used. Serum levels were significantly higher with the larger amounts of Hyskon used in ablative procedures (P less than 0.01), as compared with serum levels seen with the smaller amounts of Hyskon used for diagnostic procedures. The injection pressures should be low to minimize the amount of intravascular injection. In cases in which extensive ablative procedures are necessary, we suggest that a two-stage procedure be considered. Because of the hypertonicity of Hyskon, intravascular volume expansion that may be larger than that seen during transurethral prostatectomy occurs.

Absorption↗
PubMed1986

One versus two MAC halothane anesthesia does not alter the left ventricular diastolic pressure-volume relationship.

Previous studies on halothane's effect on left ventricular diastolic compliance (LVDC) not only have had conflicting results, but are not directly applicable to most intraoperative settings. Therefore, the authors examined in dogs whether the depth of halothane anesthesia alters LVDC under surgical conditions over a wide range of hemodynamic stresses with the cardiovascular reflexes intact. The left ventricular diastolic pressure-volume relation was examined at 1 MAC and 2 MAC halothane in seven dogs over wide ranges of preload and afterload during left thoracotomy. Pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic pressure (LVEDP), and echocardiographic left ventricular end-diastolic volume (LVEDV) were analyzed with the exponential pressure-volume relation P = AeBV (where P = pressure, V = volume, and A and B are empirically derived coefficients). Multivariate analysis showed no significant differences for diastolic pressure-volume relations, comparing both levels of halothane using either PCWP or LVEDP for pressure. The authors conclude that in the intact cardiovascular system in the healthy open-chest dog: 1) LVDC does not change with the depth of halothane between 1 and 2 MAC (it is still possible LVDC changed between 0 and 1 MAC), and 2) PCWP does reflect the LVEDV during halothane anesthesia (between 1 and 2 MAC) under surgical conditions over a wide range of cardiovascular stresses.

Anesthesia↗
PubMed1985

Arterial pulse wave velocity: a limited index of systemic vascular resistance during normotensive anesthesia in dogs.

We investigated the relationship between systemic vascular resistance (SVR) and arterial pulse wave velocity (PWV) to determine if PWV might provide an index of SVR during anesthesia. A wide range of SVR measurements was obtained pharmacologically in 8 dogs during halothane anesthesia at each of three mean blood pressure (BP) ranges: low (40 to 60 mm Hg), medium (90 to 110 mm Hg), and high (140 to 160 mm Hg). For pooled data the SVR-PWV linear correlation coefficient at the low BP range was 0.44; at the medium BP range it was 0.75; in both cases p was less than 0.001. At the high BP range the correlation coefficient was -0.06 and was not significant. We conclude that only directional trends in SVR during normotensive anesthesia (medium BP range) can be estimated using arterial PWV measurements. Thus, on the basis of this study, PWV measurement cannot be used as a direct substitute for SVR measurement. Further study of SVR-PWV relationships is needed to determine if noninvasively measured PWV might provide a more accurate estimate of SVR.

Anesthesia↗
PubMed1985

Can we trust the direct radial artery pressure immediately following cardiopulmonary bypass?

Reversal of the usual relationship between aortic and radial artery pressure can occur in patients following cardiopulmonary bypass. Radial systolic (and often radial mean) pressures were lower, relative to aortic pressure, after cardiopulmonary bypass than before bypass in all 18 patients studied. The systolic pressure difference (aortic minus radial) was large enough to be of clinical concern (12-32 mmHg) in 13 patients. The change persisted for 10-60 min, gradually returning toward normal. The change temporally was associated with warming at the end of cardiopulmonary bypass and lowered forearm vascular resistance. Relative forearm vascular resistance (x) predicted the systolic aortic minus radial pressure difference (y) by the equation y = -0.34x + 17 for all patients (r = -0.49, P less than 0.001). The authors conclude that radial artery pressure does not accurately reflect central aortic pressure in the immediate postbypass period.

Adult↗
PubMed1985

The effect of Fluosol-DA on induction of inhalation anesthesia.

The liquid/gas partition coefficients of three inhalation anesthetics in Fluosol-DA 20% (Fluosol), a perfluorocarbon blood substitute, were determined in vitro. The high values found (6.68 for halothane, 7.54 for enflurane, and 7.20 for isoflurane) suggested that induction with these agents would be prolonged in patients treated with Fluosol. Induction of isoflurane anesthesia (as a representative agent) at constant inspired concentration was studied in five mongrel dogs before and after replacement of about 25% of each animal's blood volume with Fluosol. Inspired and end-tidal isoflurane and carbon dioxide concentrations were recorded breath by breath, together with cardiac output. There was a significant delay in rise of end-tidal isoflurane concentration after Fluosol infusion. However, because cardiac output could not be held constant during each experiment, and because cardiac output also affects the rate of rise of alveolar anesthetic concentration, a physiological computer model was used to compare the isoflurane blood/gas partition coefficients that must have existed to account for the observed end-tidal levels before and after Fluosol infusion, while taking cardiac output variation into account. Post-Fluosol blood/gas partition coefficients calculated in this way (2.59 +/- 0.51 SD) were significantly different (P less than 0.001) from pre-Fluosol levels (1.45 +/- 0.15 SD) and were not significantly different from post-Fluosol partition coefficients calculated by volume-weighted averaging (2.91 +/- 0.36 SD). This indicates that the delay observed was attributable in large part to increased solubility of isoflurane in blood after addition of Fluosol. Based on their similar liquid/gas partition coefficients in Fluosol, similar delays should occur with halothane and enflurane.

Anesthesia, Inhalation↗
PubMed1979

Decrease in arterial pressure following heparin injection prior to cardiopulmonary bypass.

Evidence exists in the literature that heparin has vasodilating properties. We recorded arterial blood pressure changes that occur after administration of 300 units/kg of beef-lung heparin prior to cardiopulmonary bypass. In 37 out of 43 patients there was a significant decrease in arterial pressure following administration of beef-lung sodium heparin. Systolic blood pressure fell approximately 10 mmHg (1.3 kPa) and diastolic blood pressure fell about 5 mmHg (0.65 kPa). Heart rates remained unchanged. In 7 of the 43 patients in whom pulmonary artery catheters were placed, cardiac output was determined and systemic vascular resistance was calculated. On the basis of these calculations, it seems that a decrease in systemic vascular resistance is responsible for the decrease in arterial blood pressure noted following sodium heparin.

Blood Pressure↗
PubMedDate not supplied

Echocardiographic analysis of human left ventricular diastolic volume and cardiac performance during halothane anesthesia.

Using M-mode echocardiography we found that 0.5, 1.0, and 1.5% end-tidal halothane induced dose-related increases in left ventricular volume and decreases in left ventricular performance in seven normal unpremedicated subjects. During controlled respiration with normocarbia, the diastolic minor axis of the heart, which is related to the cube root of left ventricular volume, increased to a maximum of 107. 7 +/- 1.9 (% +/- SE of control) at 1.5% end-tidal halothane from a control value of 43.5 +/- 1.3 (mm +/- SE). Two ejection-phase performance variables, percentage shortening and mean velocity of circumferential shortening decreased to 60.1 +/- 6.1 (% +/- SE of control) and 62.4 +/- 6.5, (% +/- SE of control) at 1.5% halothane from respective control values of 29.7 +/- 2.61 (% +/- SE) and 0.94 +/- 0.08 (circumferences/second +/- SE). Surgical stimulation did not significantly affect these changes. Under these experimental conditions, we conclude that halothane dilates the heart, and that echocardiography can be used to monitor the depressant effect of halothane on the heart.

Adult↗
PubMedDate not supplied

Analysis of human epidural pressures.

BACKGROUND AND OBJECTIVES: During performance of epidural injection, entry into the epidural space has traditionally been determined by identification of negative pressure to the advancing needle by indirect means such as hanging drop; loss of resistance to air, saline, or water; or use of a MacIntosh balloon. Confusion in the literature regarding entry pressures versus postentry (baseline) pressures and zero reference pressure was noted. METHODS: Baseline epidural pressure changes were examined using a closed system zeroed to the dorsal spine during and after injection of local anesthetics in 39 patients referred to the Pain Treatment Center, located at SUNY Health Science Center, Syracuse, New York, for epidural injections. The course of epidural pressure changes after injection and the temporal relation of epidural pressure waves to the arterial and venous wave forms were examined. RESULTS: In contrast to previous investigations, subatmospheric pressure was found in the epidural space in only one patient. Baseline pressure for all patients was 7.7 +/- 3.9 mmHg. There were significant differences in baseline pressure in patients who had undergone back surgery compared with patients who had not undergone such surgery: 11.8 +/- 3.4 as opposed to 7.0 +/- 3.5 mmHg, respectively (p less than 0.005). Three minutes after a 2-ml injection of local anesthetic into the epidural space, the pressure returned to baseline. This contrasted to the effects of a 6-ml injection, which resulted in the pressure remaining above baseline after 3 minutes. The epidural pressure wave forms more closely paralleled the radial artery wave form than the central venous pressure. CONCLUSION: Lumbar epidural pressure is greater than atmospheric pressure when referenced to zero at the dorsal spine level.

Adult↗