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... Read's ideas about childbirth pain contradicted ideas long established among the public. AfterSimpson's introduction of anesthesia for women in labor, women sought medical relief from childbirth pain, often over the protests... more
... Read's ideas about childbirth pain contradicted ideas long established among the public. AfterSimpson's introduction of anesthesia for women in labor, women sought medical relief from childbirth pain, often over the protests of conservative physicians. ...
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Summary To study the function of the corpus luteum (CL) through its major secretory product, progesterone (P4), catheters were inserted into the carotid artery (via the facial artery) and the ovarian vein (n = 12), and electromagnetic... more
Summary To study the function of the corpus luteum (CL) through its major secretory product, progesterone (P4), catheters were inserted into the carotid artery (via the facial artery) and the ovarian vein (n = 12), and electromagnetic flow transducers were placed around the ovarian artery in cycling Angus and Hereford cows (n = 6). Blood samples were taken four times
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Social Values, no less than medical science, have shaped the medical management of the pain of childbirth. Nineteenth century feminists fought for greater use of anesthesia in obstetrics at a time when physicians held back for fear of its... more
Social Values, no less than medical science, have shaped the medical management of the pain of childbirth. Nineteenth century feminists fought for greater use of anesthesia in obstetrics at a time when physicians held back for fear of its effects on labor, hemorrhage, rates of infection and the condition of the child. A century later, after physicians became comfortable with the use of anesthesia, a new generation of feminists challenged the use of such drugs, once again citing social considerations. The personalities of colorful and charismatic obstetricians such as James Young Simpson and Grantley Dick-Read played a strong part in the outcome of each confrontation.
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After Morton's demonstration in the Ether Dome of the Massachusetts General Hospital, anesthesia for surgery was accepted around the world at a speed unusually fast for any medical or scientific innovation. However, the concept of... more
After Morton's demonstration in the Ether Dome of the Massachusetts General Hospital, anesthesia for surgery was accepted around the world at a speed unusually fast for any medical or scientific innovation. However, the concept of surgical anesthesia had been rejected on four occasions during the preceding 40 years. The rapid acceptance of anesthesia in 1846 appears to have had a political and social basis as well as medical. Two factors are particularly important. First was a change in the perception of disease and pain; both lost religious connotations and became biologic phenomena as part of a process of secularization that affected all aspects of Western society. Second was the growth of a sense of well-being and progress, which imbued patients and physicians alike with confidence in their ability to control natural processes. During the last half century, pain has remained secular, but the confidence in both progress and the ability to control nature may have diminished.
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The influence of Queen Victoria on the acceptance of obstetric anesthesia has been overstated, and the role of John Snow has been somewhat overlooked. It was his meticulous, careful approach and his clinical skills that influenced many of... more
The influence of Queen Victoria on the acceptance of obstetric anesthesia has been overstated, and the role of John Snow has been somewhat overlooked. It was his meticulous, careful approach and his clinical skills that influenced many of his colleagues, Tyler-Smith and Ramsbotham and the Queen's own physicians. The fact that the Queen received anesthesia was a manifestation that the conversion of Snow's colleagues had already taken place. This is not to say that this precipitated a revolution in practice. Medical theory may have changed, but practice did not, and the actual number of women anesthetized for childbirth remained quite low. This, however, was a reflection of economic and logistical problems, too few women were delivered of newborn infants during the care of physicians or in hospitals. Conversely, it is important to recognize that John Snow succeeded in lifting theoretical restrictions on the use of anesthesia.
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The effect of pretreatment with d-tubocurarine on the incidences of succinylcholine-induced fasciculations and post-operative muscle pain, and the time to onset of and 50% recovery from neuromuscular blockade were studied in 75 obstetric... more
The effect of pretreatment with d-tubocurarine on the incidences of succinylcholine-induced fasciculations and post-operative muscle pain, and the time to onset of and 50% recovery from neuromuscular blockade were studied in 75 obstetric patients. Thirty women with term pregnancies undergoing general anesthesia for elective cesarean section or cesarean section indicated by cephalopelvic disproportion were randomly assigned to two groups. Group C-1 patients received 0.05 mg/kg of d-tubocurarine followed by 1.5 mg/kg of succinylcholine, and group C-2 patients received 1.5 mg/kg of succinylcholine, and group C-2 patients received 1 ml of normal saline followed by 1 mg/kg of succinylcholine. An investigator, unaware of the relaxant regimen used, judged severity of fasciculations and postoperative muscle pain and measured times to onset of and 50% recovery from neuromuscular blockade. This same study design was followed in a group of 30 women undergoing tubal ligation 1 day after vaginal delivery (groups T-1 and T-2). The incidence of both fasciculations and postoperative muscle pain was low and was not significantly different between pretreated and nonpretreated groups. Time to 100% twitch depression was also not significantly different between pretreated and nonpretreated groups. Time to 50% recovery from neuromuscular blockade was significantly longer in both nonpretreated groups (C-2 and T-2). An additional group of 15 patients undergoing general anesthesia for cesarean section using 0.7 mg/kg of succinylcholine without d-tubocurarine pretreatment was studied (group C-3). This smaller dose of succinylcholine produced onset and 50% recovery times similar to the group pretreated with d-tubocurarine (group C-1).(ABSTRACT TRUNCATED AT 250 WORDS)
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The effect of pretreatment with d-tubocurarine on the incidences of succinylcholine-induced fasciculations and post-operative muscle pain, and the time to onset of and 50% recovery from neuromuscular blockade were studied in 75 obstetric... more
The effect of pretreatment with d-tubocurarine on the incidences of succinylcholine-induced fasciculations and post-operative muscle pain, and the time to onset of and 50% recovery from neuromuscular blockade were studied in 75 obstetric patients. Thirty women with term pregnancies undergoing general anesthesia for elective cesarean section or cesarean section indicated by cephalopelvic disproportion were randomly assigned to two groups. Group C-1 patients received 0.05 mg/kg of d-tubocurarine followed by 1.5 mg/kg of succinylcholine, and group C-2 patients received 1.5 mg/kg of succinylcholine, and group C-2 patients received 1 ml of normal saline followed by 1 mg/kg of succinylcholine. An investigator, unaware of the relaxant regimen used, judged severity of fasciculations and postoperative muscle pain and measured times to onset of and 50% recovery from neuromuscular blockade. This same study design was followed in a group of 30 women undergoing tubal ligation 1 day after vaginal delivery (groups T-1 and T-2). The incidence of both fasciculations and postoperative muscle pain was low and was not significantly different between pretreated and nonpretreated groups. Time to 100% twitch depression was also not significantly different between pretreated and nonpretreated groups. Time to 50% recovery from neuromuscular blockade was significantly longer in both nonpretreated groups (C-2 and T-2). An additional group of 15 patients undergoing general anesthesia for cesarean section using 0.7 mg/kg of succinylcholine without d-tubocurarine pretreatment was studied (group C-3). This smaller dose of succinylcholine produced onset and 50% recovery times similar to the group pretreated with d-tubocurarine (group C-1).(ABSTRACT TRUNCATED AT 250 WORDS)
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We have studied the LH secretion pattern evoked by diminution in the opioid tone produced by iv naloxone (NAL) infusion between 1100-1400 h on proestrus, the LH secretion pattern occurring spontaneously between 1430-1730 h on proestrus... more
We have studied the LH secretion pattern evoked by diminution in the opioid tone produced by iv naloxone (NAL) infusion between 1100-1400 h on proestrus, the LH secretion pattern occurring spontaneously between 1430-1730 h on proestrus and the LH secretion pattern produced by exogenous LHRH administered either as a 10 ng/pulse at 20-, 30-, or 60-min intervals or infused continuously at a rate of 30 ng/h between 1200-1700 h in rats given pentobarbital at 1100 h on proestrus. Infusion of 0.5 ng NAL/h raised plasma NAL levels to 200-300 ng/ml and augmented LH secretion, as evident by increments in pulse amplitude and frequency discharge to one every 37.5 min from an average of one every 75 min in saline-infused control rats. A 4-fold increase in circulating NAL levels, produced by 2 mg/h NAL infusion, further augmented the frequency of LH episodes to 30-33 min and induced a surge-like LH secretion pattern which resembled that seen on the afternoon of proestrus. Further analysis of the secretory pattern of the preovulatory LH surge (n = 7) showed LH pulses of increased amplitude during the basal phase (n = 4), ascending phase (n = 2), and plateau and descending phases (n = 3); in two rats the LH rise was steep, and no LH pulses were identified. A LHRH pulse (10 ng/pulse) delivered at 20- or 30-min intervals or continuous infusion of LHRH at a rate of 30 ng/h produced LH surges, with peak levels reaching the range seen on the afternoon of proestrus. Further, despite the fact that 10 ng LHRH/pulse at 20-min intervals reproduced a proestrous-type LH surge, only 40% of the LHRH pulses were followed by identifiable LH pulses. Surprisingly, despite the observations that NAL evoked robust LH episodes, the basal pattern of FSH secretion in these rats was not altered. These findings show that a decrease in opioid tone on proestrus accelerates episodic LH discharge to the range that occurs after gonadectomy. A quantitative relationship between the degree of restraint on the opioid tone imposed by NAL and the magnitude of the LH response can be demonstrated. The evidence suggests that the preovulatory LH surge may occur in an episodic fashion and that it can be reproduced by LHRH delivered at a frequency rate of LH pulses seen in ovariectomized rats.(ABSTRACT TRUNCATED AT 400 WORDS)
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To our knowledge, this is the first attempt at adapting an existing cardiovascular model to simulate the hemodynamics of a particular patient population. Despite attempts to define the physiologic alterations in advance, we discovered... more
To our knowledge, this is the first attempt at adapting an existing cardiovascular model to simulate the hemodynamics of a particular patient population. Despite attempts to define the physiologic alterations in advance, we discovered there were critical parameters not completely defined in the literature. These were discovered through the iterative process of testing, comparing resulting vital signs with targets, and literature review. A list of the parameters that should be sought for future modeling efforts is provided (Table 3), but this list is by no means exhaustive. As further work is performed in this area, additional independent and essential parameters will be identified (pressure characteristics of valvular anomalies, for example). To define a physiology that is less well described in the literature, empirical alterations and best-guess estimates of parameter changes will be required with significantly more iterations. Finally, we have described only modeling of cardiovas...
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Respiratory sinus arrhythmia is a pattern of rhythmic variation in the heart rate that occurs at the frequency of respiration and is mediated principally by the vagus nerve. Spectral analysis can decompose the variance of a series of... more
Respiratory sinus arrhythmia is a pattern of rhythmic variation in the heart rate that occurs at the frequency of respiration and is mediated principally by the vagus nerve. Spectral analysis can decompose the variance of a series of sequential measures into constituent frequencies to measure and verify whether there is respiratory sinus arrhythmia in utero in the fetal lamb. Recordings of heart period were obtained from electrodes implanted under fetal skin in six chronic preparations. Respiratory rate and heart period were recorded immediately after delivery and daily for the next 5 days. Respiratory sinus arrhythmia was clearly demonstrated in the neonatal lambs, and the same frequency of respiratory sinus arrhythmia was observed in the fetus and in the newborn lamb (0.8 to 0.1 Hz). There was a reproducible pattern of change in respiratory sinus arrhythmia from 27 days before delivery until term, with a decline in the amplitude of respiratory sinus arrhythmia 4 to 8 days before d...
Research Interests: Electrocardiography, Pregnancy, Sheep, Female, Animals, and 3 moreHeart rate, Respiration, and Fetal Heart
In a series of foetal lambs weighing between 1,100 and 5,228 g, the circulating plasma volume was estimated by the dye dilution method, using Evans Blue, to test the possibility that the plasma volume could be used as an index of foetal... more
In a series of foetal lambs weighing between 1,100 and 5,228 g, the circulating plasma volume was estimated by the dye dilution method, using Evans Blue, to test the possibility that the plasma volume could be used as an index of foetal weight in chronic studies. The data, analysed by the method of least squares regression, indicate that plasma volume and foetal weight are closely correlated (R-2 equals 0.922) and linearly so in the range of data studied. There was no evidence that the relation differed for singlets and twins. A single equation, Y equals 71.8 plus 10.11 X--where Y is the estimated weight and X the plasma volume, can be used to predict the weight from plasma volume in both. Some results of the application of the method in chronic studies are presented.
Research Interests: Pregnancy, Sheep, Female, Animals, Body Weight, and 4 moreFetus, Gestational Age, Hematocrit, and Blood Proteins
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Aspiration is common in the intubated human neonate. Thus, the ventilatory and blood gas responses to citric acid and saline instillation into different airway sites were studied in ten awake, unanesthetised lambs, breathing spontaneously... more
Aspiration is common in the intubated human neonate. Thus, the ventilatory and blood gas responses to citric acid and saline instillation into different airway sites were studied in ten awake, unanesthetised lambs, breathing spontaneously via a tracheostomy tube. With a system of balloons, 1 ml of saline or citric acid was placed selectively into the midtrachea, the laryngeal area, or the lower trachea (lower tr). Changes in minute ventilation (VE), after a 30 sec baseline period, were measured 30 sec and 1 and 2 min after the challenge. Arterial blood gas changes were measured at 30 sec and 2 min. Major increases in VE were seen only when saline or citric acid was instilled into the lower tr, the citric acid responses exceeding saline ones. The arterial oxygen tension (PaO2) fell after lower tr saline, whereas the arterial CO2 tension (PaCO2) fell with midtracheal saline instillation. A rise in pH and a fall in PaCO2 accompanied citric acid given into the lower tr. An initial rise in PaO2 after citric acid into the lower tr was followed by a return to baseline despite hyperventilation. The ventilatory and blood gas changes with saline and citric acid depend on the site of airway instillation.