Retrospective evaluation of production characteristics in Sinclair miniature swine--44 years later

Three hundred seventy-one litter records collected between 1985 and 1993 from 156 Sinclair S-1 miniature sows, a Hormel-derived strain of miniature swine, were retrospectively analyzed and compared with published records for 1950 to 1952 and 1963 to 1965. The effect of several variables such as season and month of parturition, age of sow, parity, and litter size on reproductive parameters of the Sinclair miniature swine were evaluated. The mean and standard error of the mean for litter size, number of liveborn, number of stillborn, and litter size at weaning of the Sinclair S-1 miniature swine were 7.20 +/- 0.12, 6.57 +/- 0.12, 0.63 +/- 0.06, and 5.75 +/- 0.12 piglets respectively. From a total of 2,436 liveborn piglets, 2,133 (87.56%) were weaned. The litter size at birth was similar to that previously reported for this strain of swine, whereas the litter size at weaning increased (P < 0.001) from 4.7 piglets during 1963 to 1965 to 5.8 piglets in our study. The average birth weight decreased (P < 0.001) from 0.90 kg in 1950 to 1952 and 0.72 kg in 1963 to 1965 to 0.59 kg in our study. Reproductive variables that had a considerable effect on the miniswine reproduction included month of parturition, age of sow, parity, and litter size. Primiparous sows had the smallest litter size and lowest number of weaned piglets. Sows during their second and third parity or sows between 2 and 4 years old had the best reproductive performances. Litter size and number of stillborn increased with parity and age of sow, resulting in fewer piglets weaned in older sows.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of surgical treatment for infective endocarditis in intravenous drug users

OBJECTIVE

To determine the early and late results of surgical treatment for infective endocarditis (IE) in intravenous drug users (IVDU).

DESIGN

Cohort study of consecutive IVDUs undergoing surgical treatment for IE.

SETTING

Large public hospital serving the urban population of Chicago, Ill.

PATIENTS

Consecutive IVDUs operated on between July 1982 and June 1991 for IE.

MAIN OUTCOME MEASURES

Death, stroke, noncerebral systemic embolization, major bleeding, recurrent endocarditis, and repeated valve replacement.

RESULTS

There were 80 patients, 58 men and 22 women, with a mean age of 37.5 +/- 10 (SD) years. The hospital course in all patients and follow-up data on 75 (94%) patients were complete. The primary indication for surgery was acute congestive heart failure in 44 (56%), persistent sepsis in 21 (26%), and multiple systemic embolization in 15 (19%) patients. Six patients (7.5%) died within 30 days of surgery. An additional 13 of 69 patients (17.6%) died during the follow-up, 8 from cardiovascular causes. The probability of survival at 36 months and at 60 months was 0.74 +/- 0.05 (SE) and 0.70 +/- 0.05, respectively. Seventeen (30%) of the survivors had at least one major cardiovascular event; 6 (8.8%) had recurrent endocarditis, 4 (5.8%) had stroke, 3 (4.4%) had extracerebral bleeding, 1 had extracerebral systemic embolism, and 3 (4.4%) required repeated valve replacement. Probability of event-free survival at 36 months and 60 months was 0.65 +/- 0.06 and 0.52 +/- 0.08, respectively. The median duration of event-free survival was 65 months.

CONCLUSION

Since the expected mortality without surgery in patients with IE in whom medical treatment fails is almost 100%, it is concluded that surgical treatment is indicated for, and substantially improves the outlook for early and late survival of, IVDUs with IE who fail to respond to medical management.

The technique of radial artery cannulation. Tips for maximizing results while minimizing the risk of complications

Arterial cannulation is usually performed to allow continuous blood pressure monitoring or frequent arterial blood sampling. Relative contraindications to the procedure include bleeding abnormalities and peripheral vascular disease. The radial artery is the site most frequently used because the hand generally has good collateral circulation. Percutaneous cannulation is the preferred method of insertion. To avoid transecting the artery, advance the needle-catheter assembly slowly; blood return confirms arterial placement. there should be no resistance to needle advancement. Bleeding is the most common complication of arterial cannulation, but ischemia and infection have greater clinical significance.

Improving long-term prognosis for survivors of mechanical ventilation in patients with AIDS with PCP and acute respiratory failure. Five-year follow-up of intensive care unit discharges

BACKGROUND

Before 1987, the hospital survival of patients with acquired immunodeficiency syndrome, Pneumocystis carinii pneumonia, and acute respiratory failure receiving mechanical ventilation was less than 15%. Hospital survival has improved since then, but concerns have been raised that the post-hospital discharge survival of these patients remains extremely poor. This study evaluated the long-term survival of patients discharged alive after an acute episode of acute respiratory failure caused by P carinii pneumonia.

METHODS

A prospective cohort study was conducted for the 5-year period from May 1987 through May 1992 in an urban teaching hospital. Forty-seven patients discharged from the hospital after receiving mechanical ventilation and/or continuous positive airway pressure for acquired immunodeficiency syndrome, P carinii pneumonia, and acute respiratory failure were followed up from their initial intensive care unit admission until death or termination of the study to measure the long-term survival and cumulative probability of survival of the study cohort. Actuarial life-table analysis was performed, and long-term cumulative probability of survival was calculated on the basis of the life-table analysis. Median survival was estimated by means of the product-limit method.

RESULTS

During the 5-year follow-up of the 47 subjects, 31 patients died, 12 were unavailable for follow-up, and four were still alive at the end of the cutoff. The cumulative survival rate at 1 year was 80% (95% confidence interval, 92% to 68%); at 2 years, 49% (95% confidence interval, 65% to 34%); at 3 years, 18% (95% confidence interval, 32% to 4%); and at 4 years, 6% (95% confidence interval, 17% to 0%). Median survival time for all subjects was 602 days (1.65 years), and the longest survival time for a single patient was 1774 days (4.86 years).

CONCLUSIONS

Post-hospital discharge survival of patients with acquired immunodeficiency syndrome, P carinii pneumonia, and acute respiratory failure has improved dramatically in the past decade. Patients can undergo intubation and mechanical ventilation with the hope of reasonable long-term survival.

ARE MITOCHONDRIA SUBJECT TO EVOLUTIONARY TEMPERATURE ADAPTATION?

Thermal tolerance and the respiratory properties of isolated red muscle mitochondria were investigated in Oreochromis alcalicus grahami from the alkaline hot-springs, Lake Magadi, Kenya. Populations of O. a. grahami were resident in pools at 42.8 &deg;C and migrated into water reaching temperatures of 44.8 &deg;C for short periods. The maximum respiration rates of mitochondria with pyruvate as substrate were 217 and 284 natom O mg-1 mitochondrial protein min-1 at 37 &deg;C and 42 &deg;C, respectively (Q10=1.71). Fatty acyl carnitines (chain lengths C8, C12 and C16), malate and glutamate were oxidised at 70&shy;80 % of the rate for pyruvate. In order to assess evolutionary temperature adaptation of maximum mitochondrial oxidative capacities, the rates of pyruvate and palmitoyl carnitine utilisation in red muscle mitochondria were measured from species living at other temperatures: Notothenia coriiceps from Antarctica (-1.5 to +1 &deg;C); summer-caught Myoxocephalus scorpius from the North Sea (10&shy;15 &deg;C); and Oreochromis andersoni from African lakes and rivers (22&shy;30 &deg;C). State 3 respiration rates had Q10 values in the range 1.8&shy;2.7. At the lower lethal temperature of O. andersoni (12.5 &deg;C), isolated mitochondria utilised pyruvate at a similar rate to mitochondria from N. coriiceps at 2.5 &deg;C (30 natom O mg-1 mitochondrial protein min-1). Rates of pyruvate oxidation by mitochondria from M. scorpius and N. coriiceps were similar and were higher at a given temperature than for O. andersoni. At their normal body temperature (-1.2 &deg;C), mitochondria from the Antarctic fish oxidised pyruvate at 5.5 % and palmitoyl-dl-carnitine at 8.8 % of the rates of mitochondria from the hot-spring species at 42 &deg;C. The results indicate only modest evolutionary adjustments in the maximal rates of mitochondrial respiration in fish living at different temperatures.

Life-threatening hypotension associated with emergency intubation and the initiation of mechanical ventilation

To determine the incidence of life-threatening hypotension (LTH) suffered by patients in the initial hours after emergency intubation and mechanical ventilation, prospective, consecutive case series of patients undergoing endotracheal intubation and mechanical ventilation were evaluated in the adult emergency department of a large urban hospital. Eight-four medical patients who received intubation and mechanical ventilation for ventilatory failure, respiratory failure, or airway protection (trauma patients exluded) were included. LTH, defined as a decrease in mean arterial pressure of 60 mm Hg or an absolute decrease to a systolic blood pressure < 80 mm Hg in the first 2 hours after intubation, was observed in 24 of the 84 patients who met study criteria (incidence 28.6%). Eleven patients (incidence 13.1%) required treatment for LTH with vasopressors. There was one cardiac arrest, and there were no deaths. There was a statistically significant association between LTH and hypercarbic (PCO2 > 50 mm) chronic obstructive pulmonary disease (COPD) (P = .004). There was also a weaker statistical association between LTH and hypoxemic respiratory failure (P = .019). No association could be established between LTH and the other diagnoses, arterial blood gas (ABG) derangements, or the administration of sedatives or paralytic medications. LTH represents a serious complication of emergency intubation in the initial phase of mechanical ventilation. Because it occurs in more one quarter of all cases, it should be anticipated during intubation and the initial phase of ventilator management, especially in high-risk patients such as those with hypercarbic COPD.(ABSTRACT TRUNCATED AT 250 WORDS)

MECHANICAL PERFORMANCE OF AN IN SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5 C AND 15 C

We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5&deg;C and 15&deg;C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15&deg;C and a spontaneous heart rate of 23.4 beats min-1, maximum stroke volume was 2.54 ml kg-1 body mass, maximum cardiac output was 62.5 ml min-1 kg-1 and maximum cardiac myocardial power output was 1.50 mW g-1 ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor. At 5&deg;C, the spontaneous heart rate (8.1 beats min-1) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 ml kg-1) was not significantly reduced compared with the value at 15&deg;C. The significantly lower maximum values for cardiac output (18.9 ml min-1 kg-1) and power output (0.39 mW g-1 ventricular mass) at 5&deg;C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy. Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5&deg;C than at 15&deg;C. The maximum anoxic cardiac power output value at 15&deg;C (0.77 mW g-1 ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.

Neuropeptides in the Australian lungfish Neoceratodus forsteri: effects in vivo and presence in autonomic nerves

The Australian lungfish Neoceratodus forsteri is one of the few extant species of a phylogenetically ancient group. Immunohistochemistry showed the presence of galanin-, vasoactive intestinal polypeptide (VIP)-, neurotensin-, substance P-, and calcitonin gene-related peptide (CGRP)-like immunoreactivities in nerve fibers in the heart, lung, and gut, with a coexistence of VIP-, galanin-, and somatostatin-like immunoreactivity in the lung and galanin- and somatostatin-like immunoreactivity in the gut. About 20% of the substance P-immunoreactive fibers in gut and lung contained CGRP-like material. Major vessels showed a sparse innervation. In free-swimming unanesthetized fish, neurotensin (1 nmol/kg), galanin (1 nmol/kg), and bombesin (10 nmol/kg) reduced the heart rate. In two specimens tested, the effect of neurotensin was partially antagonized by atropine. Galanin and bombesin reduced and cholecystokinin 8 (CCK-8-S) increased blood flow to the lung. Neurotensin decreased, CCK-8-S increased, and substance P had no effect on dorsal aortic pressure, and all three decreased flow to the gut. It can be concluded from the present study that the general vertebrate pattern of cardiovascular and visceral nervous control by several neuropeptides is present also in Neoceratodus.

Developing strategies to prevent inhospital cardiac arrest: analyzing responses of physicians and nurses in the hours before the event

OBJECTIVES

To determine: a) the frequency of premonitory signs and symptoms before cardiac arrest in patients on the general medical wards of a hospital; b) any characteristic patterns in nurse and physician responses to these signs and symptoms; and c) whether cardiac arrests on the ward occur more frequently in patients discharged from the medical intensive care unit (ICU) than in other patients.

DESIGN

Case series of consecutive patients who had an inhospital cardiac arrest over a 20-month period.

SETTING

General medical wards of a 1,000-bed urban public hospital.

PATIENTS

There were 21,505 total admissions to the medical service in this period. Patients whose cardiac arrests occurred in the Emergency Room and ICU and patients with do-not-resuscitate orders were excluded from the study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were a total of 150 cardiac arrests on the medical wards (cardiac arrest rate: 7.0/1,000 patients) with a hospital mortality rate of 91%. In 99 of 150 cases, a nurse or physician documented deterioration in the patient's condition within 6 hrs of cardiac arrest. Common findings included: a) failure of the nurse to notify a physician of a deterioration in the patient's mental status; b) failure of the physician to obtain or interpret an arterial blood gas measurement in the setting of respiratory distress; and c) failure of the ICU triage physician to stabilize the patient's condition before transferring the patient to the ICU. Former ICU patients (cardiac arrest rate: 14.7/1,000 patients) were more likely to suffer cardiac arrest than other patients (cardiac arrest rate: 6.8/1,000 patients) (p = .004).

CONCLUSIONS

Cardiac arrests on the general wards of the hospital are commonly preceded by premonitory signs and symptoms. Strategies to prevent cardiac arrest should include training for nurses and physicians that concentrates on cardiopulmonary stabilization and how to respond to neurologic and respiratory deterioration. Special attention should also be devoted to patients who have been discharged from the ICU who are at greater risk for cardiac arrest after ICU discharge than are other medical patients.

THE INTRINSIC PROPERTIES OF AN IN SITU PERFUSED CROCODILE HEART

An in situ perfused crocodile (Crocodylus porosus) heart preparation was developed to investigate the effects of input and output pressure on cardiac dynamics and to determine the conditions that lead to a right-to-left cardiac shunt. The pericardium was kept intact, both the left and right atria were perfused and all three outflow tracts (right aortic, left aortic and pulmonary) were cannulated, enabling pressures and flows to be monitored. The perfused heart preparation had an intrinsic heart rate of 34 beats min-1 and generated a physiological power output. Both the left and right sides of the heart were sensitive to filling pressure. Increasing the filling pressure to both atria resulted in an increase in stroke volume and cardiac output (Frank­Starling effect). Increasing the filling pressure to the right atrium also had a positive chronotropic effect. Large right ventricular stroke volumes initiated a right-to-left shunt, despite the left aorta having a pressure 1.5 kPa higher than the pulmonary output pressure. The left ventricle was able to maintain its output and stroke volume up to an output pressure of approximately 8 kPa. However, the right ventricle was significantly weaker. Right ventricular output and stroke volume showed a marked decrease when the output pressure was increased above 5 kPa. A right-to-left shunt occurred when pulmonary output pressure was increased. Surprisingly, a shunt occurred into the left aorta before the pressure in the pulmonary artery became greater than that in the left aorta. Once the pressure in the pulmonary artery exceeded the left aortic pressure, pulmonary artery flow ceased and right ventricular output was solely via the left aorta. A right-to-left shunt could also be initiated by increasing the filling pressure to the left atrium.

Contamination of human ovarian follicular fluid and serum by chlorinated organic compounds in three Canadian cities

OBJECTIVES

To determine the extent of contamination of ovarian follicular fluid and serum samples in women undergoing in-vitro fertilization and to study the effect of the contaminants on reproductive outcome.

DESIGN

Inception cohort study.

PATIENTS

Seventy-four women undergoing in-vitro fertilization at three regional clinics in Halifax, Hamilton, Ont., and Vancouver.

MAIN OUTCOME MEASURES

Follicular fluid and serum levels of contaminants, cleavage rates and time to cleavage of first egg.

RESULTS

Five chlorinated organic chemicals were frequently found in the two types of samples: alpha-chlordane (ALCH), dichlorochlorophenylethylene (DDE), heptachloroepoxide-oxychlordane (OXCH), hexachlorobenzene (HCB) and polychlorinated biphenyl (PCB). The levels were generally low. Regional differences between the three clinics were present. Samples from the Halifax clinic had the lowest frequency and level of contamination. The source of drinking water (well, bottled or municipal) was an important confounder. The concentrations of the five contaminants did not affect the cleavage rate or the time to cleavage of the first egg.

CONCLUSION

Trace amounts of toxic and persistent chlorinated organic chemicals found in the follicular fluid of Canadian women undergoing in-vitro fertilization did not seem to have any adverse biologic effect on the rate of fertilization and the time to cleavage. Reasons for regional differences in the concentrations of contaminants require further study.

The technique of percutaneous tracheostomy. Using serial dilation to secure an airway with minimal risk

Percutaneous tracheostomy is the procedure of choice for most patients who require prolonged use of an artificial airway; it can be performed rapidly at the bedside and is associated with fewer complications than is the standard procedure. The serial dilational technique involves the insertion of prelubricated dilators that gradually enlarge the diameter of a tract made by a guidewire and guiding catheter, facilitating placement of a standard double-cannula tracheostomy tube. The most dangerous complication, paratracheal insertion, occurs only rarely. The small skin incision and resulting tight fit of the tracheostomy tube in the stoma help prevent bleeding and infection.