Stress and affiliation: hospital roommate effects on preoperative anxiety and social interaction

Fifty-three preoperative men were studied who were assigned to a hospital roommate who varied in terms of the similarity of the roommate's health problem and surgical status. The similarity of a roommate's particular type of health problem to that of the patient exerted little detectable influence. However, patients assigned to a preoperative roommate were more anxious compared with those assigned a postoperative or nonsurgical roommate. Affiliation was also significantly greater with fellow preoperative roommates compared with postoperative roommates. The possibility that the obtained roommate effects on anxiety are mediated directly by affiliation is explored. Additional mechanisms and theoretical implications for basic research involving social comparison, stress, and affiliation relationships are discussed. Practical considerations for hospital policy also are considered.

Stress and affiliation: hospital roommate effects on preoperative anxiety and social interaction

Fifty-three preoperative men were studied who were assigned to a hospital roommate who varied in terms of the similarity of the roommate's health problem and surgical status. The similarity of a roommate's particular type of health problem to that of the patient exerted little detectable influence. However, patients assigned to a preoperative roommate were more anxious compared with those assigned a postoperative or nonsurgical roommate. Affiliation was also significantly greater with fellow preoperative roommates compared with postoperative roommates. The possibility that the obtained roommate effects on anxiety are mediated directly by affiliation is explored. Additional mechanisms and theoretical implications for basic research involving social comparison, stress, and affiliation relationships are discussed. Practical considerations for hospital policy also are considered.

Afferent and efferent components of the cardiovascular reflex responses to acute hypoxia in term fetal sheep

1. We studied the effects of acute isocapnic hypoxia on arterial and central venous pressures, carotid and femoral blood flows and heart rate in intact and carotid denervated fetal sheep between 118 and 125 days gestation, after pre-treatment with either saline, atropine or phentolamine. Electrocortical activity (ECoG) and the incidence of fetal breathing movements (FBM) were also compared between intact and carotid denervated fetuses. 2. There were no significant differences between intact and denervated fetuses in any variable measured during normoxia. Soon after the onset of hypoxia a marked bradycardia occurred in intact, but not in denervated fetuses. Femoral blood flow and femoral vascular resistance (perfusion pressure/femoral blood flow) increased in intact, but not in denervated fetuses. Carotid blood flow increased in both groups of fetuses during hypoxia, but carotid vascular resistance did not change. During hypoxia, the incidence of FBM and low-voltage ECoG was similarly reduced in both groups of fetuses. 3. Atropine produced a rise in fetal heart rate during the control period in intact but not in denervated fetuses. At the onset of hypoxia atropine prevented the initial bradycardia seen in intact fetuses. In denervated fetuses a further increase in heart rate occurred throughout the hypoxia. 4. All denervated fetuses treated with phentolamine died during the hypoxic challenge, but nine out of fourteen intact fetuses treated with phentolamine survived. 5. In intact fetuses which survived hypoxia after treatment with phentolamine, the increase in arterial blood pressure was smaller and the increase in femoral resistance did not occur. In these fetuses a rise in heart rate occurred in hypoxia. Carotid vascular resistance decreased during hypoxia after administration of phentolamine. 6. Our results indicate that the initial cardiovascular responses of the late gestation sheep fetus to hypoxia are reflex, and that the carotid chemoreceptors provide the afferent limb of this reflex. The bradycardia is mediated through a muscarinic pathway, as it is blocked by atropine. The femoral vasoconstriction is mediated through an alpha-adrenergic mechanism, mediated both neurally by a carotid chemoreflex and via catecholamines released directly from the adrenal medulla. Both these components are blocked by phentolamine. 7. The differences in survival between intact and denervated fetuses during hypoxia after phentolamine suggest that the carotid chemoreflex response to hypoxia involves mechanisms in addition to vagal efferents to the heart and alpha-adrenergic actions at peripheral blood vessels.(ABSTRACT TRUNCATED AT 400 WORDS)

A study of school students' long term retention of expired air resuscitation knowledge and skills

This study addresses the issue of the long term retention of Expired Air Resuscitation (EAR) knowledge and skills. The subjects were one hundred and two secondary school students, half of whom had received training in EAR procedures 5 years prior to this study. Data were collected from these subjects in relation to their knowledge of the EAR procedures and their ability to implement these procedures. In general the students who had undergone the EAR training 5 years ago performed better in the practical tasks than did their untrained counterparts. While there was virtually no difference in the theoretical knowledge section overall, the trained group did perform better on a number of questions.

Mimicking low amniotic pressure by chronic pharyngeal drainage does not impair lung development in fetal sheep

OBJECTIVE

The etiology of oligohydramnios-related pulmonary hypoplasia is not understood but is known to involve chronic lung liquid loss. We tested the hypothesis that low amniotic pressure in oligohydramnios disturbs the normal tracheal-amniotic pressure gradient to increase lung liquid loss and impair lung development.

STUDY DESIGN

Chronic pharyngeal catheterization with drainage to the exterior was used in 15 fetal sheep to mimic reduced amniotic pressure at the upper airway in the presence of normal amniotic fluid volume.

RESULTS

Pharyngeal pressures relative to amniotic pressures were negative in all drained fetuses (mean +/- SE -3.0 +/- 0.6 mm Hg), in contrast to positive pressures in controls (0.7 +/- 0.1 mm Hg). There was no significant difference in lung weight or deoxyribonucleic acid relative to body weight, or in lung morphometry, between 10 fetuses drained for 10 to 21 days and their control cotwins.

CONCLUSION

Mimicking low amniotic pressure in the upper airway by chronic fetal pharyngeal drainage does not impair lung development in fetal sheep.

The application of generalizability theory to surface electromyographic measurements during psychophysiological stress testing: how many measurements are needed?

Generalizability theory is an extension of classical reliability theory that allows multiple sources of measurement error in an experimental design to be investigated simultaneously. In the present study, generalizability theory was used to evaluate measurement error in psychophysiological test procedures used to differentiate tension headache patients from normal controls based upon measures of electromyographic (EMG) responding. Thirty-three subjects who met diagnostic criteria for tension-type headache and 40 normal control subjects who rarely or never experienced headache participated in two laboratory sessions. EMG activity of head and neck muscles was recorded while subjects performed baseline, relaxation, choice reaction time, psychomotor tracking, and cold pressor tasks. Variance components were computed for an experimental design having subjects nested within experimenters and crossed with sessions and replications. Generalizability coefficients were computed for combinations of various numbers of sessions and replications. The generalizability of EMG measures was highly variable, depending on the experimental conditions in force. The largest sources of measurement error were attributed to the unique responsiveness of individual subjects under a particular set of treatment conditions. For some stress tests currently in use, data from several testing sessions may need to be averaged in order to achieve acceptable levels of generalizability. Generalizability greater than 0.80 can be expected only rarely when data are collected during a single session. In the research setting, low generalizability may account for the failure of EMG-based stress tests to differentiate tension headache patients from controls during stressful task performance. In the clinical setting, the generalizability of information derived from "stress profiling" or muscle "scanning" techniques, which depend on results obtained during a single testing session, is doubtful.

Electromyographic and affective responses of episodic tension-type headache patients and headache-free controls during stressful task performance

Thirty-four subjects meeting diagnostic criteria for episodic tension-type headache and 42 who rarely experienced headaches participated in two laboratory sessions in which cephalic electromyographic (EMG) activity, electrodermal activity, heart rate, and finger temperature were recorded. Subjects performed relaxation, choice reaction time, psychomotor tracking, voluntary muscle contraction, and cold pressor tasks. Headache subjects showed significantly greater EMG activity than controls during baseline and stressful task performance. During relaxation, both groups reduced EMG activity from baseline levels, and there was no significant difference in EMG level between the groups during relaxation. Headache subjects reported higher levels of subjective anxiety, depression, anger, and stress than controls. Headache subjects also reported higher levels of pain than controls, and headache subjects reported greater pain during stressful task performance relative to baseline and recovery periods.

Amnioinfusion increases amniotic pressure in pregnant sheep but does not alter fetal acid-base status

To investigate the recent suggestion that fetal hypoxemia and acidemia in polyhydramnios are secondary to raised amniotic pressure, 5 to 15 L of normal saline solution was infused intraamniotically at 100 ml/min in seven ewes. Amniotic pressure increased linearly by 1.0 +/- 0.013 (mean +/- SEM) mm Hg per liter infused. Infusion of 15 L produced a mean rise in amniotic pressure of 15.2 +/- 1.2 mm Hg (p less than 0.001) but no significant change in fetal pH, PCO2, PO2, fetal heart rate, or mean arterial pressure. A similar rise in amniotic pressure and lack of change in blood gas values occurred in two control ewes infused intraperitoneally. Rupture of the membranes occurred in two of three amnioinfusions of 15 L. We conclude that acute amnioinfusion raises amniotic pressure in sheep but does not alter fetal blood gas status.

Fetal breathing during chronic lung liquid loss leading to pulmonary hypoplasia

The mechanism of oligohydramnios-related pulmonary hypoplasia (PH) is not understood, but is known to involve chronic loss of lung liquid. In order to investigate the recent suggestion that fetal breathing movements are absent or diminished in oligohydramnios-related PH, we made continuous recordings of fetal breathing movements (FBM) during chronic lung drainage in tracheostomized fetal sheep. FBM remained present throughout the drainage period. There was no significant difference in the number or duration of FBM epochs in tracheostomized fetuses compared to controls, although there was a slight reduction in incidence between 126 and 133 days (P = 0.02). PH in the fetuses undergoing chronic lung liquid drainage was confirmed by significant reductions in lung weight, volume, DNA, and total airspace, and in altered maturation. This study is consistent with other data suggesting that inhibition of FBM is not the primary mechanism of oligohydramnios-related pulmonary hypoplasia.

A naturalistic study of the relationships among electromyographic activity, psychological stress, and pain in ambulatory tension-type headache patients and headache-free controls

Twelve subjects who met diagnostic criteria for episodic tension-type headache and nine subjects who rarely or never suffered from headaches wore a computer-controlled electromyographic (EMG) activity recorder in their natural environment for 48 to 96 consecutive hours. EMG activity of the posterior neck or frontal muscles was recorded 24 hr per day. During waking hours, subjects rated their perceived levels of stress, pain, and negative affect at 30-min intervals. The EMG activity of headache and control subjects did not differ significantly, and EMG activity did not covary with stress, pain, or negative affect. Cross-correlations among EMG activity, pain, and stress revealed little evidence of leading, contemporaneous, or lagging relationships. Interrupted time series analysis showed no consistent muscle hyperactivity during a headache attack compared to a headache-free baseline period.

The role of peripheral chemoreceptors in the rapid response of the pulmonary vasculature of the late gestation sheep fetus to changes in PaO2

The effect of removing the input from the peripheral arterial chemoreceptors on pulmonary vascular responses to changes in PaO2 was examined in late gestation fetal sheep. Blood flow in the left pulmonary artery and driving pressure across the pulmonary vascular bed were monitored in chronically prepared fetal sheep at 126-129 days gestation. Five fetuses had carotid sinus and vagus nerves sectioned bilaterally and four were left intact. In normoxia (PaO2 ca. 23 mmHg) pulmonary vascular resistance was slightly greater and pulmonary blood flow reduced in the denervated group relative to the intact group but these differences were not significant. When made hypoxic (PaO2 ca. 14 mmHg), pulmonary blood flow fell and pulmonary vascular resistance increased in all fetuses. However, in the intact fetuses these changes were significantly more rapid. In all fetuses the vasoconstriction was prolonged after their return to normoxia. When made hyperoxic (PaO2 ca. 27 mmHg), pulmonary blood flow increased by a similar amount in all fetuses. We conclude that in the term fetus the peripheral chemoreceptors play no appreciable role in the maintenance of the high pulmonary vascular resistance in normoxia, or the fall in resistance produced by a rise in PaO2. The chemoreceptors do however initiate the rapid phase of pulmonary vasoconstriction in hypoxia.

Necrotising fasciitis after caesarean section--association with non-steroidal anti-inflammatory drugs. A report of 3 cases

Three cases of necrotising fasciitis following caesarean section are described. Each patient had received non-steroidal anti-inflammatory drugs (NSAIDs) in the immediate postoperative period. While the association of necrotising fasciitis and the use of NSAIDs may be coincidental, the use of this group of drugs, which impair normal defence mechanisms, should be avoided if at all possible in the postpartum patient.

Behavioral changes in fetal sheep caused by vibroacoustic stimulation: the effects of cochlear ablation

We measured the effects of 2 minutes of vibroacoustic stimulation on the activity of unanesthetized fetal sheep in utero. We were unable to detect any changes in activity after stimulation with a model 5C electrolarynx. With more powerful stimulation using a mechanical oscillator, fetal electrocortical activity desynchronized. Fetal breathing and eye movements changed with electrocortical activity and there was an increase in nuchal muscle activity. Stimulation caused a small decrease in fetal heart rate. Responses to stimulation were not seen in four of the five fetuses with bilateral cochlear ablation. These results indicate that in fetal sheep the auditory apparatus is necessary for the detection of vibroacoustic stimuli. The difference in responsiveness of the sheep and human fetus appears to be because of a difference in central processing after detection of the stimulus.

Anger and hostility in tension-type headache

A battery of standardized psychometric tests was administered to a group of 47 episodic tension-type headache sufferers and 47 headache-free controls. Compared to controls, headache subjects showed higher levels of anxiety, depression, and anger/hostility. The groups did not differ significantly on a measure of anger expressed toward persons or objects, but headache subjects showed significantly greater levels of suppressed anger. The results provide objective data that are in general agreement with predictions derived from psychosomatic theories about the interrelationships among anxiety,

Quantitative studies of the vasculature of the carotid body in fetal and newborn sheep

Resetting of the hypoxic sensitivity of the carotid chemoreceptors from the fetal to the adult arterial PO2 range follows the rise in PO2 which occurs after birth. The mechanism of this resetting is unknown. To study whether it is accompanied by a change in the carotid body microvasculature, 2 pairs of carotid bodies from fetal sheep (145 days gestation) and 2 pairs from 7-8 days-old lambs were examined. The ratio of the area of small vessels (6-16 microns diameter) or of larger vessels (greater than 16 microns diameter) to the total area of individual lobules of the carotid body was measured, using a semi-automatic image analysis system. This quantified the number and total cross-sectional area of small vessels and of larger vessels in 20 sections of 5 microns thickness taken at random from 200-350 sections cut from each carotid body. When the carotid bodies of the fetus and neonate were compared, the neonates showed increases in the percentage of the lobule area occupied by both small and large vessels, but the difference was only significant in the case of the larger vessels. There was no difference in the ratio of the area occupied by smaller vessels to the extravascular area of the lobule. Our results do not support the idea that the post-natal resetting of chemoreceptor sensitivity from the fetal to the post-natal range is accompanied by a change in the perfusion of the carotid body chemoreceptor cells.

A technique for the long-term application of surface electrodes

A technique is reported for the long-term application of surface electrodes for ambulatory electromyographic (EMG) recording. Prior to electrode application the surrounding skin is lightly painted with tincture of benzoin. This treatment improves adherence to the skin of disposable electrodes and electrode attachment collars, reduces skin trauma associated with electrode removal, and minimizes sensitivity to electrode adhesives.

Spatial organization of the assembly pathways of glycoproteins and complex polysaccharides in the Golgi apparatus of plants

The Golgi apparatus of plant cells is the site of assembly of glycoproteins, proteoglycans, and complex polysaccharides, but little is known about how the different assembly pathways are organized within the Golgi stacks. To study these questions we have employed immunocytochemical techniques and antibodies raised against the hydroxyproline-rich cell wall glycoprotein, extensin, and two types of complex polysaccharides, an acidic pectic polysaccharide known as rhamnogalacturonan I (RG-I), and the neutral hemicellulose, xyloglucan (XG). Our micrographs demonstrate that individual Golgi stacks can process simultaneously glycoproteins and complex polysaccharides. O-linked arabinosylation of the hydroxyproline residues of extensin occurs in cis-cisternae, and glycosylated molecules pass through all cisternae before they are packaged into secretory vesicles in the monensin-sensitive, trans-Golgi network. In contrast, in root tip cortical parenchyma cells, the anti-RG-I and the anti-XG antibodies are shown to bind to complementary subsets of Golgi cisternae, and several lines of indirect evidence suggest that these complex polysaccharides may also exit from different cisternae. Thus, RG-I type polysaccharides appear to be synthesized in cis- and medial cisternae, and have the potential to leave from a monensin-insensitive, medial cisternal compartment. The labeling pattern for XG suggests that it is assembled in trans-Golgi cisternae and departs from the monensin-sensitive trans-Golgi network. This physical separation of the synthesis/secretion pathways of major categories of complex polysaccharides may prevent the synthesis of mixed polysaccharides, and provides a means for producing secretory vesicles that can be targeted to different cell wall domains.

Almitrine mimics hypoxia in fetal sheep with lateral pontine lesions

Almitrine bimesylate is a potent and long-lasting respiratory stimulant in adult species. It acts by stimulating the peripheral chemoreceptors, where it has been shown to accumulate specifically, although its exact mechanism of action is uncertain. In the fetal lamb, however, it produces a profound inhibition of breathing even after denervation of the peripheral chemoreceptors. In this respect its action is similar to hypoxia. To investigate whether almitrine is hypoxia mimetic, we examined the effect of almitrine in nine fetal lambs of 120-130 days gestation. Five had lesions in the lateral pons that changed the fetal depressive response to hypoxia to one of stimulation. In the remaining four fetuses, the lesions did not bilaterally encompass the appropriate area of the pons; thus they still showed the normal fetal depressive response to hypoxia and so acted as controls. Almitrine (10 mg iv) caused a pronounced stimulation of breathing that lasted 406 +/- 26 min in all five fetuses with lesions that caused a stimulatory response to hypoxia. However, in the remaining four fetuses, in which the response to hypoxia was inhibitory, almitrine caused an inhibition of breathing that lasted 184 +/- 28 min. We conclude that the action of almitrine is like that of hypoxia and that, because it acts specifically on the chemoreceptors, it may prove to be a useful tool in the study of possible central chemoreceptor mechanisms.

The relative risks of caesarean section (intrapartum and elective) and vaginal delivery: a detailed analysis to exclude the effects of medical disorders and other acute pre-existing physiological disturbances

OBJECTIVE

To compare maternal mortalities attributable to vaginal delivery, elective caesarean section (CS) and intrapartum CS.

DESIGN

The number of deaths associated with each method of delivery was ascertained among unselected and among low-risk women by detailed retrospective review of the case-notes of women who died after delivery. The frequency of each method of delivery throughout the study period was ascertained from the computer database and enhanced by analysis of the case-notes of unselected groups of women.

SETTING

The Peninsula Maternity Services (Cape Town) during the years 1975-1986 inclusive.

SUBJECTS

A total of 108 maternal deaths arising from 263,075 maternities provided accurate information. The relative frequency of vaginal and abdominal delivery was determined from the computer database. The ratio of elective CS to emergency prepartum CS to intrapartum CS was obtained by review of the first 200 operations in the years 1975, 1977, 1979, 1982 and 1984.

MAIN OUTCOME MEASURES

(i) Mortality rates associated with the different methods of delivery in unselected women and in women who were healthy before surgery; (ii) mortality rates apparently attributable to the method of delivery.

RESULTS

The overall relative risk of mortality associated with caesarean section compared with vaginal delivery was 7 decreasing to 5 after the exclusion of women with medical or life-threatening antenatal complications (eg, haemorrhage, hypertension). The relative risk associated with intrapartum compared with elective sections was 2.3 decreasing to 1.4 after the exclusion of women with medical disorders or life-threatening complications. The relative risk of maternal mortality which was apparently attributable to intrapartum compared with elective sections was 1.7. However, the 95% confidence intervals of these values, even from this large data-set, are wide. Nevertheless, these rates are in broad agreement with an approximation derived from the British confidential enquiries into maternal deaths.

CONCLUSION

The attributable relative mortalities of caesarean section compared with vaginal delivery and intrapartum compared with elective caesarean section are lower than the overall relative mortalities of these modes of delivery and are approximately 5:1 and 1.5:1 respectively. These data are crucially important in the decision to recommend elective caesarean section compared with trial of labour.

Aquatically acquired Aeromonas hydrophila wound infection. A report of 3 cases

The occurrence of Aeromonas hydrophila wound infections in healthy hosts after water-associated injury is being reported more frequently. This paper reports our experience with 3 such cases and outlines the importance of recognising the association between a water-related injury and this organism.

Ventilation tube duration versus design

Two ventilation tube designs were simultaneously compared in children in order to determine their relative rates of extrusion. The results show a twofold difference between the extrusion of the Shepard compared to the "Sheehy" or collar-button pattern of tube. Subjected to statistical analysis, these findings are highly significant.

Sacrococcygeal teratomas in the fetus and newborn

Two cases of fetal sacrococcygeal teratomas, both resulting in obstructed labor and intrauterine death, are presented. A suggested scheme of antenatal and intrapartum management of these rare tumors is recommended. The diagnosis can be made antenatally by ultrasound examination. The mode of delivery depends on the tumor size and the fetal condition. Fetal prognosis is excellent if an atraumatic delivery is followed by appropriate and timely surgery in a tertiary center.

The effects of psychological stress on electromyographic activity and negative affect in ambulatory tension-type headache patients

Fourteen female dental hygiene students (seven with episodic tension-type headache and seven who rarely or never experienced headache) wore an ambulatory electromyographic recorder and completed hourly subjective ratings of pain and negative affective states for six days while they carried out their normal daily activities. Three of the days were designated as high stress days by virtue of the fact that the students were required to take a major course examination or undergo a clinical evaluation on that day. The remaining three days were designated as low stress days by virtue of the fact that no unusual demands were made on the students, and they simply attended lectures as usual. All students showed significantly greater levels of electromyographic activity on the high stress days compared to the low stress days, but there was not a statistically significant difference between the headache and control groups. Headache group subjects reported significantly higher levels of pain compared to the control group, but their pain ratings did not differ between high and low stress days. Subjective ratings of negative affective states (anxiety, anger, sadness, and frustration) were significantly greater on high stress days compared to low stress days. Headache group subjects also exhibited a tendency to report higher levels of negative affective states than did control group subjects, but only in the case of frustration was the .05 level of statistical significance achieved.

Escherichia coli O157:H7 haemorrhagic colitis. Report of the first South African case

Escherichia coli O157:H7, although recognised 15 years ago, has only become a significant pathogen since 1982 when two outbreaks of haemorrhagic colitis due to this organism were described in the USA. Since then, numerous such outbreaks have been reported. Recent experience with a patient presenting with E. coli O157:H7-induced haemorrhagic colitis is described. The main features, pathological findings and investigations are described and the principles of management outlined.