Biomedical subjects

G B Martin

Publications and source records attributed to G B Martin.

At least 163 records · Page 9Linked to original sources

PubMed1988

Seasonal and hormonal control of pulsatile LH secretion in the dairy goat (Capra hircus).

In Exp. 1, the changes in pulsatile LH secretion at the onset of the breeding season were observed in 20 intact, mature Saanen does. Blood was sampled every 20 min for 6 h each week from the beginning of August until the onset of ovulatory activity, as evidenced by cycles in plasma progesterone. The first doe ovulated at the end of August and all were cycling by the end of September. As the first ovulation approached, LH pulse frequency increased by 67% and mean levels of LH increased by 47%. These changes were progressive rather than abrupt. In Exp. 2, seasonal changes in the inhibition of pulsatile LH secretion by ovarian steroids were studied in ovariectomized Saanen does. The animals were untreated (N = 4) or given subcutaneous oestradiol implants (N = 4) and blood was sampled every 10 min for 6 h, twice during the breeding season and twice during the anoestrous season. In each season, the second series of samples was taken after the animals had been treated with progesterone, administered by intravaginal implants. Season did not significantly affect LH secretion in goats not treated with oestradiol, but LH pulse frequency was 54% lower during the anoestrous season than during the breeding season in oestradiol-treated goats. Mean LH concentrations were affected in the same manner as pulse frequency, but pulse amplitude was increased by oestradiol treatment in both seasons. Progesterone had no detectable effect on LH secretion in either season. In Exp. 3, the response to repeated melatonin injections at a set time after dawn was investigated in 11 oestradiol-treated, ovariectomized goats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Changes in the feedback control of gonadotrophin secretion in ewes from lines selected for testis size in the ram lamb.

The dynamics of FSH and LH secretion were studied in sheep genetically selected for High (H) and Low (L) rates of testis growth. Gonadotrophin secretion had previously been shown to be affected in the ram lamb with H-line lambs more sensitive to steroid feedback than L. While there were significant differences in mean LH concentrations during the luteal and follicular phases of the oestrous cycle, mean LH values were essentially similar in the two lines in response to ovariectomy, the effect of oestradiol implants on the response to ovariectomy and the response to LHRH. However, the frequency of LH pulses in the H line was similar during both phases of the oestrous cycle, showing a surprising insensitivity to steroid feedback. By contrast, LH pulse frequency was markedly lower in the L-line ewes in the luteal than the follicular phase (0.6 vs 1.1 pulses/h) as expected from the literature. Mean FSH concentrations were significantly higher in the L-line ewes during the follicular phase of the oestrous cycle and after ovariectomy but no significant differences were detected at the other sampling periods. There were no differences in ovulation rate between the lines. It was concluded that selection for testis size had affected the feedback control of gonadotrophin release in the ewe, as in the ram, and hence the expression of the genes controlling this is not sex limited.

Animals↗

PubMed1988

Effects of breed, ovarian steroids and season on the pulsatile secretion of LH in ovariectomized ewes.

The effects of season and of oestradiol and progesterone on the tonic secretion of LH were studied in ovariectomized Merino and Suffolk ewes, two breeds which differ markedly in the seasonal pattern of their reproductive activity. In the absence of exogenous steroids, the frequency of LH pulses was lower and the amplitude of the pulses was higher in anoestrus than in the breeding season for Merino and Suffolk ewes 30 days after ovariectomy. In long-term (190 days) ovariectomized ewes, this seasonal change in LH secretion was observed in Suffolk ewes only. During seasonal anoestrus, treatment of ewes with subcutaneous oestradiol-17 beta implants (3, 6 or 12 mm in length) decreased the frequency of LH pulses in a dose-dependent manner, with Suffolk ewes being far more sensitive to the inhibitory effects of oestradiol than Merino ewes. The lowest dose of oestradiol (3 mm) had no effect on the secretion of LH in Merino ewes, but reduced secretion in Suffolk ewes. Treatment of ewes with the highest dose of oestradiol (12 mm) completely abolished LH pulses in Suffolk ewes, whereas infrequent pulses remained evident in Merino ewes. During the breeding season, oestradiol alone had no effect on the pulsatile release of LH in either breed, but in combination with progesterone there was a significant reduction in LH pulse frequency. Progesterone effectively decreased LH secretion in both breeds in both seasons. It was concluded that differences between breeds in the 'depth' of anoestrus could be related to differences in the sensitivity of the hypothalamus to both negative feedback by oestradiol and the direct effects of photoperiod.

Animals↗

PubMed1988

Changes in the secretion of LH pulses, FSH and prolactin during the preovulatory phase of the oestrous cycle of the ewe and the influence of treatment with bovine follicular fluid during the luteal phase.

It has previously been shown that treatment of ewes with bovine follicular fluid (bFF) throughout the luteal phase of the oestrous cycle lowers plasma levels of FSH but increases the frequency and amplitude of the pulses of LH. Under these conditions, ovarian follicles grow to a maximum diameter of 2.7 mm and have a reduced capacity to release oestradiol. We have examined the nature of the gonadotrophin signals controlling follicular development in the normally cycling ewe and have investigated the effects of previous exposure to bFF on these signals and the follicular responses to them. Control ewes (n = 7) were injected i.v. with 9 ml bovine serum and treated ewes were injected with 9 ml bFF, twice daily from days 1 to 10 of the luteal phase (day 0 = oestrus). The ewes were injected with prostaglandin analogue on day 11 of the cycle to induce luteolysis and the gonadotrophin patterns were studied in blood sampled from these animals every 10 min for up to 72 h during the subsequent follicular phase. Following luteolysis (and the end of bFF treatment), LH pulse frequency increased rapidly in both groups and reached 1 pulse/h within 6 h. Thereafter, pulse frequency increased marginally and reached 1 pulse/50 min by the onset of the LH surge. This pattern was not affected by previous treatment with bFF. In the control ewes, the amplitude of the LH pulses did not change significantly following luteolysis or at any time during the follicular phase, while the levels of FSH declined slowly until the onset of the surge. In the treated ewes, on the other hand, there was an immediate increase in both LH pulse amplitude and the concentration of FSH immediately after the end of bFF treatment at luteolysis, and they remained above control levels for 24 and 16 h respectively. Plasma prolactin levels did not appear to change around the time of luteolysis but showed a marked and significant diurnal rhythm (nadir around noon and peak around midnight) in both groups. The concentrations of prolactin were significantly (P less than 0.001) lower and the preovulatory peak was delayed and reduced in the bFF-treated ewes relative to controls. The onset of oestrus was also significantly (P less than 0.01) delayed by bFF treatment, but the ovulation rates did not differ between the groups. Furthermore, comparisons within or between groups revealed no significant relationships between any of the variables of plasma LH secretion during the follicular phase and the subsequent ovulation rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1987

Hypothalamic multiunit activity and LH secretion in conscious sheep.

The relationship between the pulsatile secretion of luteinizing hormone (LH) and multiunit activity (MUA) in the median eminence and retrochiasmatic area (RCh-ME) of the hypothalamus was investigated within 13 conscious, ovariectomized ewes during the anoestrous season. Eight of the ewes had been treated with oestradiol to reduce their LH pulse frequency. To test whether the activity had been recorded from sites involved in the control of GnRH release, we electrically stimulated the sites studied with the recording electrode and used the LH responses to classify the animals retrospectively for analysis of the MUA data. Following stimulation, LH secretion was either stimulated (Group STIM, n = 5 ewes), inhibited (Group INHIB, n = 4) or showed no response (Group NR, n = 4). Statistical analysis of the MUA data revealed that the onset of LH pulses was associated with an increase in cell activity in STIM ewes and a decrease in activity in both Group INHIB and Group NR ewes. Histological examination revealed that the electrodes were located near the midline in Group STIM ewes, but 1.25 or 2 mm lateral of the midline in Groups NR and INHIB, respectively. We concluded that the MUA in the RCh-ME probably reflects the activity of cells with fibres or terminals involved in the control of GnRH release. Activity which increased at the onset of LH pulses was detected in medial areas of the RCh-ME and may reflect the activity of GnRH neurones. The activity which decreased at the onset of LH pulses in lateral areas of the RCh-ME suggests that both stimulatory and inhibitory inputs may be involved in the release of GnRH pulses.

Animals↗

PubMed1987

LHRH and beta-endorphin in the hypothalamus of the ram in relation to photoperiod and reproductive activity.

The regional distribution and relative concentrations of LHRH and beta-endorphin immunoreactivity in the hypothalamus were compared in sexually active and sexually inactive Soay rams. LHRH was localized principally in the medial basal hypothalamus and median eminence with lower concentrations in the anterior hypothalamus and preoptic area. beta-endorphin immunoreactivity was also found in highest concentrations in these regions but was more widely distributed into the rostral, dorsal and lateral parts of the hypothalamus. LHRH content in the medial basal hypothalamus was significantly lower in the sexually active rams compared to inactive rams while there was no difference in beta-endorphin immunoreactivity content between the two groups. Gel filtration chromatography of hypothalamic extracts revealed that the beta-endorphin immunoreactivity was due to both beta-lipotropin and beta-endorphin; the ratio of beta-endorphin: beta-lipotropin tended to be less in the sexually active rams than in the sexually inactive rams. The results are consistent with the hypothesis that beta-endorphin is a physiologically important endogenous opioid involved in the modulation of LHRH secretion.

Animals↗

PubMed1987

Cardiopulmonary bypass vs CPR as treatment for prolonged canine cardiopulmonary arrest.

Although in vitro studies have demonstrated functional recovery of neurons after prolonged ischemia, in vivo experience with patients resuscitated from cardiopulmonary arrest demonstrates much less cerebral resistance to global ischemia. The purpose of our investigation was to compare the effectiveness of femoro-femoral veno-arterial cardiopulmonary bypass (CPB) to standard cardiopulmonary resuscitation in the treatment of prolonged cardiopulmonary arrest. Ten mongrel dogs were electrically fibrillated and left in cardiopulmonary arrest without any therapy for 12 minutes. Subsequently, either CPB (n = 5) or CPR (n = 5) was initiated and resuscitation attempted according to a standardized protocol that included administration of the calcium channel blocker lidoflazine in an effort to optimize cerebral and myocardial recovery. If there was return of spontaneous circulation, the animal was managed in an intensive care setting with invasive hemodynamic monitoring and ventilatory support for up to nine hours. Neurologic function was graded using a standardized neurologic deficit scoring (NDS) system at 12 hours after insult and daily for one week or until death. Prearrest hemodynamic and metabolic parameters were comparable in both groups (P greater than .05). All CPB animals were resuscitated successfully and alive at 24 hours after insult as opposed to none in the CPR group (P less than .005). In addition, three of the CPB animals were neurologically normal at final grading with NDS scores of zero. The other two CPB animals had persistent severe neurologic impairment and a mean NDS score of 51%. Thus CPB is more effective than CPR in the treatment of prolonged cardiopulmonary arrest. The improved outcome probably results primarily from improvement in blood flow with CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Lactic acidosis during closed-chest CPR in dogs.

Survival after out-of-hospital cardiac arrest is intimately related to the time from cardiovascular collapse to the initiation of CPR, or downtime. Furthermore, the reperfusion technique that optimizes coronary and cerebral blood flow after cardiac arrest may also be dependent on downtime. Peak blood lactate levels have been shown to be unchanged throughout resuscitation and predictive of downtime in dogs subjected to cardiopulmonary arrest and open cardiac massage. The purpose of this study was to determine the course of arterial lactate levels in dogs subjected to a fibrillatory cardiopulmonary arrest and conventional closed-chest CPR (CCPR). Fourteen dogs were subjected to five minutes of cardiopulmonary arrest and 30 minutes of CCPR. Resuscitation was performed according to a standardized protocol. Arterial lactic acid samples were collected at timed intervals throughout the experiment. Mean arterial lactic acid levels increased significantly with each sampling interval during 30 minutes of CCPR (overall P less than .05). In nine dogs successfully resuscitated, there were no significant differences in mean arterial lactic acid levels after the return of spontaneous circulation (ROSC). Open-chest resuscitation after five minutes of ventricular fibrillation in dogs results in peak lactic acid levels that do not change significantly once internal cardiac massage is initiated. In contrast, CCPR in similarly arrested dogs does not appear to provide adequate tissue oxygenation and/or perfusion to prevent continuous lactic acid accumulation.

Acidosis, Lactic↗

PubMed1987

Selective venous hypercarbia during human CPR: implications regarding blood flow.

Thirty-five patients presenting to the emergency department in cardiopulmonary arrest had simultaneous measurement of central venous (cv) and arterial (a) blood gases during CPR with a pneumatic chest compressor and ventilator. The mean cv, arterial pH, and PCO2 values were markedly different (P less than .001). The mean pH gradient (pHa - pHcv) was .31 +/- .10 units and the mean PCO2 gradient (PcvCO2 - PaCO2) was 60.5 +/- 23.6 torr. This selective venous hypercarbia is probably due to a cardiac output that is inadequate to eliminate the CO2 produced from both residual aerobic metabolism and the buffering of anaerobically produced lactic acid. Central venous blood gases are probably a better reflection of actual tissue environment during prolonged cardiac arrest than are arterial blood gases.

Aged↗

PubMed1987

Pulsatile LH secretion during the preovulatory surge in the ewe: experimental observations and theoretical considerations.

The secretion of LH during the preovulatory surge has been shown to be pulsatile in several species. We confirmed this phenomenon in intact ewes in two experiments in which we studied the LH surge in detail. In the first experiment, the levels of LH were measured in discrete blood samples taken every 5 min around the onset of oestrus in 5 intact Merino ewes. For 2-5 h immediately prior to the onset of the surge, the median pulse interval was 17.5 min (range 10-55) and the median pulse amplitude was 0.70 ng/ml (range 0.28-1.33 ng/ml). During the ascending phase of the surge, the pulse interval did not change significantly (median 18.3 min) but the median pulse amplitude increased 20 fold to 18.0 ng/ml. During the descending phase, the median pulse interval was 22.5 min and the median amplitude decreased to 8.1 ng/ml (P less than 0.005). During the surge, intervals of 10 min and amplitudes over 30 ng/ml were common. In the second experiment with 2 oestrous Romanov x Préalpes-du-Sud ewes, blood was withdrawn continuously and samples were pooled over 4 min periods for 19-27 h. In the resulting profiles, individual pulses were better defined but the pulse frequencies (median interval 15.2 min during ascending phase) and amplitudes (median 35.0 ng/ml) varied in similar fashion to the Merinos. Using a simple mathematical description of pulsatile secretion, and assuming that LH is only released in pulses, we also found that the high concentrations normally achieved during the surge can only be explained by pulse frequencies and amplitudes well above those normally observed in other physiological situations, including the follicular phase or following ovariectomy. These findings strongly support the experimental data and the combined results of the two studies suggest that the initiation and execution of the LH surge is probably accomplished by changes in the amplitude of pulses. A high frequency is also essential and our data suggest that it may be established some time before the onset of the surge proper, but this requires confirmation. Respectively, the changes in amplitude and frequency reflect the pituitary and hypothalamic components of the positive feedback mechanism. The theoretical study suggested that a change in clearance rate could also contribute to the surge and this awaits further investigation.

Animals↗

PubMed1987

Effect of immunization against progesterone on oestrus, cycle length, ovulation rate, luteal regression and LH secretion in the ewe.

The effects of active immunization against progesterone on reproductive activity were studied in Merino ewes. Immunization against progesterone caused a shortening (P less than 0.01) of the interval between ovulations from 17-18 days (controls) to between 6 and 10 days (immunized group); this was associated with a corresponding reduction in the interval between LH surges. The immunized ewes also had higher (P less than 0.05) ovulation rates (1.72) than controls (1.25) and exhibited a reduced (P less than 0.01) incidence of oestrus (26% v. 95%). Many immunized ewes continued to ovulate despite the persistence of corpora lutea from earlier ovulations which led to an accumulation on the ovaries of many corpora lutea of different ages. The frequency of LH pulses in ewes immunized against progesterone (1.8 +/- 0.2 pulses/4 h) was significantly (P less than 0.001) higher than that of control ewes (0.3 +/- 0.1 pulses/4 h). This study highlights the importance of progesterone in the control of oestrus, ovulation, ovulation rate, luteal regression and the secretion of LH in the ewe.

Animals↗

PubMed1987

Differential transcription of the two glutamine synthetase genes of Bradyrhizobium japonicum.

Bradyrhizobium japonicum induces the formation of nitrogen-fixing symbiotic root nodules on soybean plants. The B. japonicum genome encodes two isoforms of glutamine synthetase (GS). One form, GSI, encoded by the gene glnA, is similar in structure and activity to the enzyme found in all other bacteria. The second form, GSII, encoded by glnII, is structurally related to the eucaryotic enzyme. Genetic analyses indicate that glnA or glnII alone is sufficient to provide glutamine prototrophy, whereas the double mutation glnA glnII produces glutamine auxotrophy. The glnA gene is transcribed from a single promoter that has a structure most similar to that of the bacterial consensus promoter. The level of transcription of glnA is not specifically affected by nitrogen limitation of growth. The glnII gene is also transcribed from a single promoter; however, this promoter has structural features characteristic of promoters controlled by the nitrogen regulation system. In contrast to glnA, physiological studies indicate that glnII transcription is regulated in response to nitrogen source availability. Under aerobic growth conditions, expression of glnII is induced when growth is limited by nitrogen source depletion as expected for regulation by the nitrogen regulation system.

Amino Acid Sequence↗

PubMed1987

Season influences FSH concentration in ovariectomized Ile-de-France ewes.

Ile-de-France ewes were ovariectomized during anoestrus or the mid-luteal phase of an oestrous cycle (day of ovariectomy = Day 0). In a short-term study, FSH concentrations were measured in blood samples collected hourly the day before and on Days 1, 3, 7 and 15 after ovariectomy (10 ewes per group). FSH concentrations increased significantly from 6.1 to 16.5 ng/ml within 1 day of ovariectomy and increased further to 47.1 ng/ml by Day 15. Differences between seasons of ovariectomy were not significant. In a long-term study, FSH concentrations were measured in blood samples collected hourly on Days 7, 15, 30, 60, 90, 120, 150 and 180 after ovariectomy in anoestrus or the breeding season (10 ewes per group). Further samples were taken (5 ewes/group) at 240 and 365 days after ovariectomy. The pattern of change in FSH after ovariectomy differed between the two seasons and the interaction between season and sampling day was significant. For ewes ovariectomized during anoestrus, FSH concentrations increased to a maximum by Day 180 and remained high thereafter. In contrast FSH increased more slowly in ewes ovariectomized in the breeding season and differences between the groups were significant from Day 90 to Day 270. However, both groups had similar FSH concentrations at Day 365. These results show that FSH concentrations increase rapidly after ovariectomy. There are seasonal differences in FSH concentrations in the absence of ovarian feedback with increases in FSH concentration around the time of the onset of the breeding season. Once FSH concentrations had reached a maximum, major seasonal changes were no longer apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗

PubMed1987

Effect of small doses of bovine follicular fluid on the tonic secretion of gonadotrophins in the ewe.

Previous work has shown that treatment of ewes with steroid-free bovine follicular fluid (bFF), a rich source of inhibin, partially inhibits the increase in mean plasma concentrations of LH induced by ovariectomy. The present experiment was designed to test the hypothesis that this effect was a reflection of reduced LH pulse amplitude which would only be expressed at high (pharmacological) doses of bFF. To do this, we assessed the dose-response to bFF of the secretion of FSH and LH pulses in intact and acutely ovariectomized ewes. In intact ewes, a low dose of bFF (0.2 ml s.c. every 8 h) had no detectable effect on the secretion of FSH, an intermediate dose (0.6 ml s.c. every 8 h) depressed FSH concentrations for about 24 h and a high dose (1.8 ml s.c. every 8 h) reduced FSH concentrations to undetectable levels. In ewes treated with 1.8 ml bFF, FSH concentrations also remained undetectable after ovariectomy and did not increase until treatment was withdrawn. In ewes treated with 0.6 ml bFF, FSH concentrations were maintained at normal intact levels for about 32 h following ovariectomy but then rose to normal ovariectomized levels. In ewes treated with 0.2 ml bFF, FSH concentrations increased immediately after ovariectomy but more slowly than in control ovariectomized ewes. Profiles of LH pulses were recorded after ovariectomy, during and after the withdrawal of bFF treatment. In ewes treated with the highest dose (1.8 ml s.c. every 8 h), mean LH levels and pulse amplitude were lower than in control ewes and increased significantly following withdrawal of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Effect of adrenalectomy on LH release in sheep during the anoestrous season.

An experiment was conducted to measure LH pulse frequencies in bilaterally adrenalectomized Ile-de-France ewes during the mid-anoestrous season. Seven ewes were adrenalectomized under general anaesthesia and maintained on daily injections of 3 mg deoxycorticosterone acetate (DOCA). Adrenalectomy did not affect the patterns of LH release and the mean intervals between pulses in the adrenalectomized and sham-operated control ewes were 48 and 52 min respectively. Small implants of oestradiol significantly reduced the frequency of LH pulses in both groups and, in the presence of oestradiol, there were no differences in LH release between adrenalectomized and sham-operated ewes, with the mean interpulse intervals being 91 and 89 min respectively. In a second experiment, designed to assess the effects of DOCA on LH release, the mean interpulse intervals in unoperated control ewes (46 min) and unoperated ewes given daily injections of 3 mg DOCA (47 min) were similar to those observed in adrenalectomized and sham-operated ewes. In the presence of small implants of oestradiol, the combination of DOCA and oestradiol decreased the pulse frequency significantly more than oestradiol alone (mean interpulse intervals of 85 and 65 min respectively) suggesting that DOCA may act as a progestagen in sheep. Thus alternative treatments to DOCA for the maintenance of adrenalectomized sheep must be found for future studies on the role of adrenal steroids in the reproductive system. It appears that adrenal steroids do not play a major role in the seasonal changes in LH release in the ewe.

Adrenal Glands↗

PubMed1987

Endogenous opioid control of pulsatile LH secretion in rams: modulation by photoperiod and gonadal steroids.

The role of endogenous opioid peptides in the inhibitory control of pulsatile LH secretion was studied in adult Soay rams at different stages of the seasonal reproductive cycle, entrained by an artificial lighting regimen of alternating 16-week periods of long and short days. The LH responses to the acute administration of naloxone (opioid antagonist) and morphine (opioid agonist) were measured in intact rams (n = 7), testosterone-implanted castrated rams (n = 8) and castrated rams (n = 8) to assess the interaction between photoperiod and gonadal steroids in the opioid control of LH secretion. In the intact and testosterone-implanted castrated rams, naloxone (1.7 mg/kg i.v.) increased and morphine (1.0 mg/kg i.v.) decreased mean LH concentrations and LH pulse frequency during the sexually active phase under short days, but these effects were reduced or absent during the inactive phase under long days. The changes in the LH responses occurred in close parallel with the photoinduced changes in endogenous LH secretion. In the castrated rams receiving no supplementary testosterone, plasma LH concentrations were permanently raised and there were only minor changes related to the photoperiod. Naloxone (1.7 mg/kg) induced transient increases in LH secretion at all stages, and morphine (1.0 mg/kg) failed to suppress LH levels under both short and long days. LHRH stimulation tests revealed that there were changes in LH release related to the induced reproductive cycle in the intact and testosterone-implanted rams but not in the castrated rams; these changes in the responsiveness of the pituitary gonadotrophs to LHRH could not account for the changes in the LH response to the opiate drugs. These results illustrate that an endogenous opioid mechanism is involved in the tonic inhibition of LH secretion acting to regulate the pulsatile release of LHRH from the hypothalamus. This system can be shown to be functional in a steroid-dependent manner in the sexually active phase of the seasonal cycle, but not in the inactive phase of the cycle when non-opioidergic mechanisms are presumed to predominate in the inhibition of LH secretion.

Animals↗

PubMed1986

Aortic and right atrial pressures during standard and simultaneous compression and ventilation CPR in human beings.

Coronary perfusion pressure, as reflected by the diastolic aortic to right atrial (Ao-RA) pressure gradient, has been shown to correlate well with coronary blood flow during standard external CPR (SE-CPR) and is an important determinant of successful cardiac resuscitation. Few studies have documented such Ao-RA gradients in human beings, however. Twenty patients sustaining out-of-hospital cardiopulmonary arrests and basic cardiac life support were instrumented with thoracic aortic and right atrial catheters on arrival in the emergency department. The mean time from arrival in the ED to catheter placement was 16.5 +/- 6.0 minutes. With SE-CPR, peak systolic aortic and right atrial pressures were 73.7 +/- 20.2 mm Hg and 69.6 +/- 18.3 mm Hg, respectively. End diastolic aortic and right atrial pressures were 27.9 +/- 7.3 mm Hg and 20.3 +/- 7.2 mm Hg, respectively, with an end diastolic gradient of 7.9 +/- 9.1 mm Hg. Three patients had systolic Ao-RA gradients of more than 25 mm Hg, which is consistent with some cardiac compression as a mechanism of flow. Five patients also had one-minute trials of simultaneous compression and ventilation CPR (SCV-CPR). Ao-RA end diastolic gradients decreased in four of the five during SCV-CPR. No patient in this study was resuscitated successfully. We conclude that ED SE-CPR provides little coronary perfusion for victims of prehospital cardiac arrest. Although SCV-CPR has been shown to improve carotid blood flow in human beings, it appears to have an adverse effect on the already minimal myocardial perfusion provided by SE-CPR.

Aged↗

PubMed1986

Alternate therapy for traumatic pneumothorax in "pocket shooters".

Traumatic pneumothorax is a common complication of the IV drug abusers in Detroit who utilize the "pocket shot" (the central approach to the internal jugular vein). Fourteen patients who sustained a total of 16 pneumothoraces (two with bilateral collapse) and who underwent catheter aspiration of a simple pneumothorax (CASP) were studied prospectively. The sizes ranged from less than 10% to 100%. In addition, there was one tension pneumothorax and one pneumomediastinum. The 16 CASP procedures produced 13 successful lung expansions (82%). The remaining three were treated with tube thoracostomy and admission. Twelve of the 13 patients in whom the procedure was successful returned for followup, and all of these had 100% continued full expansion. CASP appears to be a safe, efficacious, and cost-effective treatment for the drug abuser with simple traumatic pneumothorax. With the current pressures of cost containment, this less-invasive approach with outpatient management should be studied as initial potential treatment for any simple pneumothorax.

Adult↗