Infrared tympanic temperature as a predictor of rectal temperature in warm and hot conditions

BACKGROUND

Infrared (IR) thermometry has been proposed as a rapid, non-invasive means of monitoring core temperature. However, it has not been validated for use in warm to hot environments.

HYPOTHESIS

IR tympanic temperature (Tty) accurately predicts rectal temperature (Tre) during simulated marching in warm and hot conditions.

METHODS

Tty, and thermistor-derived Tre, aural canal (Tac) and cheek skin (T cheek) temperatures were monitored in seven males during 100 min of treadmill walking, in combat uniforms, at 5 km.h-1, slope 6%, in warm (30 degrees C, 60% RH) and hot (40 degrees C, 30% RH) conditions.

RESULTS

Tty was significantly different to Tre in hot, but not warm, conditions. Final Tty was 0.2 degrees C < Tre in warm, but 0.4 degrees C > Tre in hot, conditions. From 60-100 min of the warm trial, Tty predicted Tre with a standard error of estimate (SEE) of 0.15 degrees C (r = 0.9, p < 0.0001). In a multiple regression model, the combination of Tty, Tac, and Tcheek reduced this SEE to 0.1 degrees C. In the H trial, from 60-100 min Tty predicted Tre with a SEE of 0.21 degrees C (r = 0.7, p < 0.0001). Tty and Tac correlated significantly in both trials.

CONCLUSIONS

(1) the IR method should provide useful estimates of Tre in the field provided the influence of ambient conditions is taken into account; (2) the IR method is not as reliable as rectal monitoring in distinguishing accurately between degrees of heat strain; and (3) Tre prediction with the IR device may be improved in warm conditions if skin temperatures are combined with Tty.

[Infrared temperature measurement in the ear canal with the DIATEK 9000 Instatemp and the DIATEK 9000 Thermoguide. Comparison with methods of temperature measurement in other body parts]

Temperature of the tympanic membrane is recommended as a "gold standard" of core-temperature recording. However, use of temperature probes in the auditory canal may lead to damage of tympanic membrane. Temperature measurement in the auditory canal with infrared thermometry does not pose this risk. Furthermore it is easy to perform and not very time-consuming. For this reason infrared thermometry of the auditory canal is becoming increasingly popular in clinical practice. We evaluated two infrared thermometers-the Diatek 9000 Thermoguide and the Diatek 9000 Instatemp-regarding factors influencing agreement with conventional tympanic temperature measurement and other core-temperature recording sites. In addition, we systematically evaluated user dependent factors that influence the agreement with the tympanic temperature.

MATERIALS AND METHODS

In 20 volunteers we evaluated the influence of three factors: duration of the devices in the auditory canal before taking temperature (0 or 5 s), interval between two following recordings (30, 60, 90, 120, 180 s) and positioning of the grip relative to the auditory-canal axis (0, 60, 180 and 270 degrees). Agreement with tympanic contact probes (Mon-a-therm tympanic) in the contralateral ear was investigated in 100 postoperative patients. Comparative readings with rectal (YSI series 400) and esophageal (Mon-a-therm esophageal stethoscope with temperature sensor) probes were done in 100 patients in the ICU. The method of Bland and Altman was taken for comparison.

RESULTS

Shortening of the interval between two consecutive readings led to increasing differences between the two measurements with the second reading decreasing. A similar effect was seen when positioning the infrared thermometers in the auditory canal before taking temperatures: after 5 s the recorded temperatures were significantly lower than temperature recordings taken immediately. Rotation of the devices out of the telephone handle position led to increasing lack of agreement between infrared thermometry and contact probes. Mean differences between infrared thermometry (Instatemp and Thermoguide, CAL-Mode) and tympanic probes were -0.41 +/- 0.67 degree C (2 SD) and -0.43 +/- 0.70 degree C, respectively. Mean differences between the Thermoquide (Rectal-Mode) and rectal probe were -0.19 +/- 0.72 degree C, and between the Thermoguide (Core Mode) and esophageal probe -0.13 +/- 0.74 degree C.

DISCUSSION

Although easy to use, infrared thermometry requires careful handling. To obtain optimal recordings, the time between two consecutive readings should not be less than two min. Recordings should be taken immediately after positioning the devices in the auditory canal. Best results are obtained in the 60 degrees position with the grip of the devices following the ramus mandibulae (telephone handle position). The lower readings of infrared thermometry compared with tympanic contact probes indicate that the readings obtained represent the temperature of the auditory canal rather than of the tympanic membrane itself. To compensate for underestimation of core temperature by infrared thermometry, the results obtained are corrected and transferred into core-equivalent temperatures. This data correction reduces mean differences between infrared recordings and traditional core-temperature monitoring, but leaves limits of agreement between the two methods uninfluenced.

Clinical outcome and long-term quality of life after surgical correction of Hirschsprung's disease

One hundred seventy-eight of 330 patients were recalled after undergoing surgery for histologically proven Hirschsprung's disease (HD). One hundred fifteen were older than 4 years at interview (Mean age, 10 years). This sample appeared to be representative of the whole in terms of demographic features such as ethnic group, sex, length of aganglionic segment, timing of presentation and surgery performed. Anthropomorphic indices for weight and height were comparable to norms, but many younger patients were below expected weight for age. In general, weight and height for age was regained with time. Nine patients had delayed developmental milestones, which were owing to specific causes in four. Nine patients had a poor functional outcome, of which two had neurological impairment. Satisfactory school performance was achieved in all but 19 (26%) of the remaining patients. Long-term functional results were comparable for the Soave and Duhamel procedures with less favorable results noted following the Swenson procedure. Assessment of complications demonstrated a significantly (P < .01) lower incidence of constipation, sexual dysfunction, and micturition disturbance following the Soave procedure when compared with the Duhamel and Swenson procedures. Neurological impairment and length of aganglionic segment beyond the rectosigmoid area appeared to influence functional outcome, as did persisting enterocolitis. Enterocolitis was observed in 16.6% of patients on presentation, but continued in only 6%. Constipation was particularly associated with the Duhamel procedure, and a higher incidence of micturition disturbance, abdominal distension, and cuff stricture was noted following the Swenson procedure. Functional assessment by three different scoring methods showed that 86 (74.7%) of the 115 patients over the age of 4 had excellent anorectal function and appeared to be well adjusted. Twenty-two patients (19.2%) had relatively minor long-term problems but seven (6.1%) had persistent fecal soiling with resulting psychosocial maladjustment.

Agreement between rectal and tympanic membrane temperatures in marathon runners

STUDY OBJECTIVE

To determine the agreement between rectal temperature and infrared tympanic membrane temperatures in marathon runners presenting to a field hospital at the finish line.

METHODS

The subjects of this prospective, blinded, controlled study were runners 18 years or older who were triaged to the acute care medical area at the finish line for suspected hypothermia, hyperthermia, dehydration, or altered mental status. Rectal and tympanic temperatures were measured simultaneously in all subjects for whom rectal temperature measurement had been deemed necessary and recorded on separate data cards.

RESULTS

Of the 239 runners treated in the acute care medical area, 37 required rectal temperature measurement and were enrolled in the study. The mean rectal temperature was 38.45 degrees +/- 1.20 degrees C (range, 35.9 degrees to 41.5 degrees C). The mean tympanic membrane temperature was 37.81 degrees +/- 95 degrees C (range, 36.3 degrees to 40.4 degrees C). Pearson's correlation coefficient revealed a moderate correlation (r = .6902, P = .00023). The mean temperature difference between the two thermometers, mean rectal minus mean tympanic membrane, was .64 degrees C (95% confidence interval, .35 degrees to .93 degrees C). Sixty-Two percent of the tympanic membrane readings were within 1 degree C of their rectal counterparts. Agreement ranged from 1.16 degrees (+2 SD) to -2.95 degrees (-2 SD). The 95% confidence interval was 1.67 degrees to -2.95 degrees C.

CONCLUSION

We were able to demonstrate only a moderate correlation between the two thermometer readings, with a wide spread between the limits of agreement. This spread could be clinically significant and therefore limits the usefulness of tympanic temperature in the marathon race setting. Because of the potentially large and clinically significant differences in rectal and tympanic temperatures and the limitations inherent in our study, we cannot endorse the use of tympanic temperature in the setting of a marathon event.

Existence of a high pressure zone at the rectosigmoid junction in normal Indian men

PURPOSE

A hypertonic, electrically hyperactive segment has been described in the rectosigmoid region mainly in constipated persons. Anatomic or manometric evidence to satisfy the criteria for a sphincter here is, however, inconclusive. We evaluated the pressure profile of the rectosigmoid region in normal Indian men.

METHODS

Fifteen male volunteers with regular bowel habits were studied. Rectosigmoid manometry (1 cm station pull-through) was done in the fasting state using a water-perfused system and three-lumen catheter with radially oriented recording ports 5 cm apart.

RESULTS

Eight volunteers had a zone of high pressure. Proximal extent of this zone was identified as the station with a rise in basal pressure of at least 10 mmHg over the previous station. A further rise of at least 10 mmHg in subsequent distal stations was considered essential for defining the existence of the zone. This zone had a median length of 3 cm, with midpoint at median 18 cm from the anal verge and median highest pressure of 36 mmHg. There was no antegrade pressure gradient across the zone; rectal pressures were higher than those in the sigmoid in 12 of 15 volunteers.

CONCLUSIONS

Approximately one-half of normal Indian men with regular bowel habits have a high pressure zone in the rectosigmoid region. The role of diet or defecation posture in its etiology and its effect on bowel habit need to be studied.

Manometric evaluation of constipation--Part I

Tests of anorectal function have evolved into clinically useful investigations, and they should no longer be regarded as esoteric tools. This transformation has led to major advances in understanding, diagnosis, and treatment of defecation disorders, such as constipation. Because constipation is a heterogeneous condition, it cannot be assessed by a single test. Judicious use of anorectal manometry, colon transit study, a test of simulated defecation, and defecography may provide invaluable pathophysiological information. Undoubtedly, examination of rectal and anal pressure activity, rectal sensation, rectoanal reflexes, and the functional morphology of the defecation unit provides more information than any other test of gastrointestinal motor function; however, there is no uniform criteria for defining manometric abnormalities. There is also an urgent need for establishing international standards for manometric techniques and for diagnosis. Nevertheless, knowledge and experience have paved the way for innovative diagnostic techniques and therapeutic approaches for patients with constipation.

Post-exercise thermal homeostasis as a function of changes in pre-exercise core temperature

We have previously reported that, following continuous exercise, a prolonged elevated plateau of esophageal temperature (Tes) was directly related to the Tes at the time of cutaneous vasodilation (Thdil) during exercise. In order to investigate the hypothesis that the factors which result in an increase of the post-exercise Thdil and define the post-exercise Tes elevation are related to pre-exercise Tes, nine healthy, young [24.0 (1.9) years], non-training males rested at 29 degrees C, 50% humidity for > 1 h (control). They then completed three successive cycles of 15 min treadmill running at 70% maximal oxygen consumption (VO2max) followed by 30 min rest. Esophageal, rectal (Tre) and skin (Tsk) temperatures and forearm cutaneous blood flow were recorded at 5-s intervals throughout. Laser-Doppler flowmetry of forearm skin blood flow was used to identify the Thdil during exercise. Pre-exercise Tes was 36.74 (0.25) degrees C and post-exercise Tes fell to stable and significant (P < 0.05) elevations above pre-exercise values at 37.22 (0.27) degrees C, 37.37 (0.27) degrees C and 37.48 (0.26) degrees C following each successive work bout respectively. Correspondingly, Thdil during each work bout rose in proportion to, and was not different than, the post-exercise Tes in the following recovery [37.20(0.23) degrees C, 37.41 (0.24) degrees C and 37.58 (0.24) degrees C]. Although the increases were less with each successive exercise bout, the differences between each exercise bout, in terms of post-exercise Tes and Thdil values, were significant (P < 0.05). These results reinforce our previous observations of elevations in Thdil and post-exercise Tes after a single exercise bout and lead to the tentative conclusions that (1) pre-exercise Tes has a direct influence on Thdil and post-exercise Tes, and (2) the exercise-induced increase of Thdil persists into recovery, influencing post-exercise thermal recovery.

Skin to skin care:heat balance

Skin to skin care has been practised in primitive and high technology cultures for body temperature preservation in neonates. Regional skin temperature and heat flow was measured in moderately hypothermic term neonates to quantitate the heat transfer occurring during one hour of skin to skin care. Nine healthy newborns with a mean rectal temperature of 36.3 degrees C were placed skin to skin on their mothers' chests. The mean (SD) rectal temperature increased by 0.7 (0.4) degrees C to 37.0 degrees C. The heat loss was high (70 Wm-2) from the unprotected skin of the head to the surrounding air. Minute heat losses occurred from covered areas; and heat was initially gained from areas in contact with the mother's skin. The total dry heat loss during skin to skin care corresponded to heat loss during incubator care at 32-32.5 degrees C. The reduced heat loss, and to a minor extent, the initial heat flux from the mothers allowed heat to be conserved, leading to rewarming.

Preservation of continence after posterior sagittal surgery

PURPOSE

An animal study was performed to evaluate the effect of posterior sagittal pararectal mobilization on anorectal sphincter function.

MATERIALS AND METHODS

We initially divided 11 juvenile pigs into 3 groups: group 1-anesthesia alone (3), group 2-posterior sagittal incision alone (4) and group 3-posterior sagittal incision with unilateral pararectal dissection (4). Two animals in group 1 subsequently underwent posterior sagittal incision with circumferential pararectal dissection (group 4). The anal canal was preserved intact in all animals. Anorectal sphincter manometry was performed preoperatively, and 2, 4, 8 and 12 weeks postoperatively. Electromyography was performed 12 weeks postoperatively. Anorectal sphincter muscle complexes were harvested for histological examination.

RESULTS

All animals had postoperative bowel continence. Postoperatively manometry revealed no difference from preoperative measurements in all study groups (p = 0.90). Electromyography and histological examination of the anorectal sphincters were normal in all but 2 animals. Denervation injury and histological atrophy were detected after repair of inadvertent enterotomy in 1 animal following unilateral pararectal dissection, and polyphasic motor unit potentials implying reinnervation were detected in another after circumferential pararectal mobilization.

CONCLUSIONS

These results indicate that posterior sagittal incision and unilateral pararectal mobilization cause no permanent injury to the anorectal sphincter. However circumferential pararectal dissection or repair of a rectal injury may cause measurable changes in sphincter function.

Ileocecal reservoir reconstruction with physiologic function after total mesorectal cancer excision

BACKGROUND/AIMS

After proctectomy for low rectal cancer and straight coloanal reconstruction, the main causes for increased daily stool frequency, urgency, and incontinence are the limited capacity and distensibility of the anastomosed colic segment in the pelvis. The authors postulated that a pedunculated (preserving the nerve) ileocecal interpositional graft (cecum-reservoir) placed between the sigmoid colon and the anal canal would greatly reduce these inconveniences.

METHODS

The authors evaluated the safety, defecation quality, and anorectal physiology of such a neorectum in 20 consecutive patients with rectal carcinoma between 5 and 10 cm above the anal verge who underwent total mesorectal excision.

RESULTS

No perioperative morbidity related to the technique and no mortality was observed in these 20 patients. Six months after the operation, 16 patients showed excellent and 4 patients good defecation quality, with maximal tolerable volumes, compliance, and mean colonic transit times comparable to age- and gender-matched healthy volunteers. In addition, anal resting pressure was decreased, squeeze pressure was maintained, and the rectoanal inhibitory reflex remained positive in 80%.

CONCLUSIONS

The cecum-reservoir as a neorectum, using an intact neurovascular colonic segment, is a safe technique, providing excellent defecation quality. It enables a nearly normal physiologic anorectal function, which is already seen 6 months postoperatively.

Long-term effect of vaginal deliveries on anorectal function in normal perimenopausal women

PURPOSE

This study was undertaken to determine the long-term effects of vaginal deliveries on anorectal function in healthy perimenopausal women.

METHODS

An observational study of 144 perimenopausal women living in the county of Aarhus, Denmark, aged 45 to 57 (mean, 50) years were randomly selected from the National Register. All women had delivered 0 to 6 (mean, 2) times 10 to 34 years before the investigation. Examinations describing pelvic floor function were measurements of perineal position at rest and descent during straining, anal mucosa electrosensitivity, maximum resting pressure and maximum squeeze pressure of the anal sphincters, and pudendal nerve terminal motor latency. All tests were performed by one of the authors (AMR) and without knowledge of parity. Data were analyzed using the multiple regression technique, and all associations between anorectal function and parity were corrected for age and hysterectomy status.

RESULTS

Increasing parity correlated with a lowered perineal position at rest (correlation coefficient (r) = 0.26; P = 0.003), an increased descent during straining (r = 0.24; P = 0.006), an increased threshold of anal mucosa electrosensitivity (r = 0.22, P = 0.008), and an increased pudendal nerve terminal motor latency on both sides (r = 0.27; P = 0.002). No effect of parity of the maximum resting pressure (r = 0.06; P = 0.70) and maximum squeeze pressure (r = 0.06; P = 0.36) was found. The number of vaginal deliveries account for only a minor fraction of the total variability seen in the tests of pelvic floor function (between 1.6 and 5.7 percent).

CONCLUSION

Repeated vaginal deliveries have a long-term adverse effect on anorectal physiology in a population of randomly selected healthy perimenopausal women.

Effect of octreotide on anal pressure and rectal compliance

PURPOSE

The somatostatin analog, octreotide, has previously been found to influence rectal sensation and may also influence anal resting pressure.

METHODS

We studied the effect of octreotide on anal resting pressure and rectal compliance in eight healthy patients. Octreotide was administered intravenously as a bolus injection in doses of 100 and 10 micrograms or as infusion of 250 micrograms/hour on separate days and compared with placebo.

RESULTS

Within one minute after a bolus injection of 100 micrograms of octreotide, anal resting pressure increased from 56 +/- 12 to 96 +/- 16 cm H2O (P < 0.005). Octrotide had no effect on rectal sensitivity or compliance measurements. Octreotide counteracted rectoanal reflex by increasing anal pressure almost to the level found with an empty rectum.

CONCLUSION

Somatostatin thus seems to contribute to the regulation of rectoanal reflex.

Practical use of rectal medications in palliative care

The rectal route of drug administration is an efficient and economical method for pharmacologic intervention in the terminally ill patient for whom the oral route is precluded. This review first describes the physiology and general considerations surrounding rectal drug administration, then evaluates the literature pertaining to analgesic and adjuvant medications and dosage forms that are and are not approved for rectal administration by the U.S. Food and Drug Administration. A paucity of studies deal with rectal administration in terminally ill patients, and data have been gathered from pharmacokinetic studies or studies in which the drugs were used for other indications. Where plausible, practical clinical recommendations for the rectal use of opioids, nonopioid analgesics, anxiolytics, and other adjuvants are formulated.

Spinothalamic and spinohypothalamic tract neurons in the sacral spinal cord of rats. I. Locations of antidromically identified axons in the cervical cord and diencephalon

1. A goal of this study was to determine the sites in the diencephalon to which neurons in sacral spinal segments of rats project. Therefore, 95 neurons were recorded extracellularly in spinal segments L6-S2 of rats that were anesthetized with urethan. These neurons were activated initially antidromically with currents < or = 30 microA from a monopolar stimulating electrode placed into the contralateral posterior diencephalon. The mean +/- SE current for antidromic activation from these sites was 16 +/- 0.8 microA. These neurons were recorded in the superficial dorsal horn (4%), deep dorsal horn (89%), and intermediate zone and ventral horn (4%). 2. Systematic antidromic mapping techniques were used to map the axonal projections of 41 of these neurons within the diencephalon. Thirty-three neurons (80%) could be activated antidromically with currents < or = 30 microA only from points in the contralateral thalamus and are referred to as spinothalamic tract (STT) neurons. Eight neurons (20%) were activated antidromically with low currents from points in both the contralateral thalamus and hypothalamus, and these neurons are referred to as spinothalamic tract/ spinohypothalamic tract (STT/SHT) neurons. Three additional neurons were activated antidromically with currents < or = 30 microA only from points within the contralateral hypothalamus and are referred to as spinohypothalamic tract (SHT) neurons. The diencephalic projections of another 51 neurons were mapped incompletely. These neurons are referred to as spinothalamic/unknown (STT/ U) neurons to indicate that it was not known whether their axons ascended beyond the site in the thalamus from which they initially were activated antidromically. 3. For 31 STT neurons, the most anterior point at which antidromic activation was achieved with currents < or = 30 microA was determined. Fourteen (45%) were activated antidromically only from sites posterior to the ventrobasal complex (VbC) of the thalamus. Sixteen STT neurons (52%) were activated antidromically with low currents from sites at the level of the VbC, but not from more anterior levels. One STT neuron (3%) was activated antidromically from the anteroventral nucleus of the thalamus. 4. STT/SHT neurons were antidromically activated with currents < or = 30 microA from the medial lemniscus (ML), anterior pretectal nucleus (APt), posterior nuclear group and medial geniculate nucleus (Po/MG), and zona incerta in the thalamus and from the optic tract (OT), supraoptic decussation, or lateral area of the hypothalamus. No differences in the sites in the thalamus from which STT and STT/SHT neurons were activated antidromically were apparent. Five STT/SHT neurons (62%) were activated antidromically from points in the thalamus in the posterior diencephalon and from points in the hypothalamus at more anterior levels. Three STT/SHT neurons (38%) were activated antidromically with currents < or = 30 microA from sites in both the thalamus and hypothalamus at the same anterior-posterior level of the diencephalon. All three of these STT/SHT neurons projected to the intralaminar nuclei (parafascicular or central lateral nuclei) of the thalamus. 5. Seven STT/SHT neurons were tested for additional projections to the ipsilateral brain. Two (29%) were activated antidromically with currents < or = 30 microA and at longer latencies from sites in the ipsilateral diencephalon. One could only be activated antidromically from the hypothalamus ipsilaterally. The other was activated antidromically at progressively increasing latencies from points in the ipsilateral brain that extended as far posteriorly as the posterior pole of the MG. 6. Fifty-eight STT, STT/SHT, and STT/U neurons were classified as low-threshold (LT), wide dynamic range (WDR), or highthreshold (HT) neurons based on their responsiveness to innocuous and noxious mechanical stimuli applied to their cutaneous receptive fields.(ABSTRACT TRUNCATED)

Spinothalamic and spinohypothalamic tract neurons in the sacral spinal cord of rats. II. Responses to cutaneous and visceral stimuli

1. A goal of this study was to determine whether neurons in the sacral spinal cord that project to the diencephalon are involved in the processing and transmission of sensory information that arises in the perineum and pelvis. Therefore, 58 neurons in segments L6-S2 were activated antidromically with currents < or = 30 microA from points in the contralateral diencephalon in rats that were anesthetized with urethan. 2. Responses to mechanical stimuli applied to the cutaneous receptive fields of these neurons were used to classify them as low-threshold (LT), wide dynamic range (WDR) or high-threshold (HT) neurons. Twenty-two neurons (38%) responded preferentially to brushing (LT neurons). Eighteen neurons (31%) responded to brushing but responded with higher firing frequencies to noxious mechanical stimuli (WDR neurons). Eighteen neurons (31%) responded only to noxious intensities of mechanical stimulation (HT neurons). LT neurons were recorded predominantly in nucleus proprius of the dorsal horn. Nociceptive neurons (WDR and HT) were recorded throughout the dorsal horn. 3. Cutaneous receptive fields were mapped for 56 neurons. Forty-five (80%) had receptive fields that included at least two of the following regions ipsilaterally: the rump, perineum, or tail. Eleven neurons (20%) had receptive fields that were restricted to one of these areas or to the ipsilateral hind limb. Thirty-eight neurons (68%) had cutaneous receptive fields that also included regions of the contralateral tail or perineum. On the perineum, receptive fields usually encompassed perianal and perivaginal areas including the clitoral sheath. There were no statistically significant differences in the locations or sizes of receptive fields for LT neurons compared with nociceptive (WDR and HT) neurons. 4. Thirty-seven LT, WDR, and HT neurons were tested for their responsiveness to heat stimuli. Five (14%) responded to increasing intensities of heat with graded increases in their firing frequencies. Thirty-two LT, WDR, and HT neurons also were tested with cold stimuli. None responded with graded increases in their firing frequencies to increasingly colder stimuli. There were no statistically significant differences among the responses of LT, WDR, and HT neurons to either heat or cold stimuli. 5. Forty LT, WDR, and HT neurons were tested for their responsiveness to visceral stimuli by distending a balloon placed into the rectum and colon with a series of increasing pressures. Seventeen (43%) exhibited graded increases in their firing frequencies in response to increasing pressures of colorectal distention (CrD). None of the responsive neurons responded reproducibly to CrD at an intensity of 20 mmHg, and all responded at intensities of > or = 80 mmHg. More than 90% responded abruptly at stimulus onset, responded continuously throughout the stimulus period, and stopped responding immediately after termination of the stimulus. 6. Thirty-one neurons were tested for their responsiveness to distention of a balloon placed inside the vagina. Eleven (35%) exhibited graded increases in their firing frequencies in response to increasing pressures of vaginal distention (VaD). The thresholds and temporal profiles of the responses to VaD were similar to those for CrD. Twenty-nine neurons were tested with both CrD and VaD. Thirteen (45%) were excited by both stimuli, four (14%) responded to CrD but not VaD, and one (3%) was excited by VaD but not CrD. Neurons excited by CrD, VaD, or both were recorded throughout the dorsal horn. 7. As a population, WDR neurons, but not LT or HT neurons, encoded increasing pressures of CrD and VaD with graded increases in their firing frequencies. The responses of WDR neurons to CrD differed significantly from those of either LT or HT neurons. Regression analyses of the stimulus-response functions of responsive WDR neurons to CrD and VaD were described by power functions with exponents of 1.6 and 2.4, respectively.(ABSTRACT TRUNCATED)

Modulation of spinal visceral nociceptive transmission by NMDA receptor activation in the rat

1. Thirty-three neurons in the L6-Sl spinal cord of 30 adult male Sprague-Dawley rats were characterized for responses to colorectal distention (CRD, 20-80 mmHg, 20 s) and convergent cutaneous receptive fields in the presence and absence of N-methyl-D-aspartate (NMDA; 1 microM) or D-serine (1 microM) administered locally by pressure ejection. 2. NMDA ejected locally increased the resting (spontaneous) activity, responses to CRD, postdistention afterdischarges, encoding of visceral nociception, and the size of convergent cutaneous receptive fields of some neurons. Facilitation of responses to noxious intensities of CRD (> or = 40 mmHg) was apparent between 30 s and 4 min after drug ejection. The slope of stimulus-response functions to graded intensities of CRD was increased significantly by NMDA, although mean response threshold was not significantly altered after NMDA ejection. 3. Facilitatory effects of NMDA on responses to CRD and increases in size of convergent cutaneous receptive fields were blocked or reversed by administration of the NMDA receptor antagonist, 5-amino-2-phosphono-valeric acid. 4. D-serine, an agonist at the glycine modulatory site on the NMDA receptor complex, generally mimicked the effects of NMDA on neurons responsive to CRD. The effects of D-serine were blocked by the glycine site antagonist 7-chloro-kynurenic acid (7-CK). 7-CK also blocked NMDA-produced effects on responses to CRD and increases in size of cutaneous receptive fields. 5. No differences were found between spinal neurons with and without documented long ascending projections with respect to effects of NMDA or D-serine. 6. These findings demonstrate involvement of spinal NMDA receptors in mediating hyperexcitability of spinal neurons to visceral nociceptive input and suggest an important contribution of spinal NMDA receptors in visceral hyperalgesic syndromes.

A quantitative study of silver-stained NORs in different segments of the normal human colorectal crypt

Quantification of silver-stained nucleolar organiser regions (AgNORs) in paraffin sections may provide clues about the proliferation and differentiation in normal and neoplastic tissues. The aim of the present investigation was to determine whether AgNOR quantification could provide useful data about proliferation in the different segments of the normal human colorectal crypt. Samples of histologically 'normal' large intestine (n = 8) were obtained from colorectal cancer resections at a distance of > 5 cm from the tumour margins and were routinely processed for paraffin embedding using strictly standardised procedures. Sections were cut and stained with a one-stage silver colloid impregnation technique. The longitudinally sectioned crypts were divided into proliferative (P), intermediate (I) and surface (S) segments using strict criteria. Clearly defined AgNORs, which appeared as black dots within the nuclear profile, were quantified from each segment for volume density (Vv) and number per unit area (NA) estimates using traditional point-counting techniques. A 1-way analysis of variance followed by Scheffe's test indicated significant progressive reductions of AgNOR Vv and NA from P to S segments. Our data suggest that both volume and frequency of AgNORs may be related to cellular proliferation since both parameters are highest in the P segment. The further exploitation of stereological tools in conjunction with AgNOR staining may be valuable in assessing normal differentiation and proliferation patterns and in predicting the biological behaviour of neoplastic tissues in which increased proliferation is a feature.

Electromyography and manometry of the pelvic colon--a contribution to the understanding of its function

OBJECTIVE

To study the adaptation of the rectum to pressure waves in the sigmoid and the motility response to the administration of a bile salt microenema.

DESIGN

Electrical and motor activity was studied in 20 men and 20 women during a 2-h fast and for 2 h after a 1000-kcal meal, and also after a bile salt microenema.

METHODS

An intraluminal probe with three sets of two electrodes and one miniballoon was used for simultaneous EMG and manometry recording.

RESULTS

Four types of spike bursts were observed: (1) migrating long spike bursts that initiated propagating pressure waves on 99% of occasions; (2) non-migrating long spike bursts that did not originate pressure waves; (3) rhythmic short spike bursts that were also not related to pressure waves; and (4) rhythmic long spike bursts that originated rhythmic segmental pressure waves frequently brought up by a migrating long spike burst. The meal significantly increased the duration of activity of the migrating long spike bursts in the sigmoid colon (from 16.8% before the meal to 21.8% after it, P < 0.05) and the motility index, P < 0.05, both of them in two peaks. A rectosigmoidal pressure gradient was shown. The bile salt microenema produced a desire to defecate and increased motility in only half of the cases.

CONCLUSION

The rectosigmoidal pressure gradient was due to: (1) higher-amplitude pressure waves in the sigmoid colon than in the other two sites, and (2) propagating relaxation waves in the rectum and in the rectosigmoid junction.

Melatonin rhythm is not shifted by lights that suppress nocturnal melatonin in humans under entrainment

Effects of a single light exposure on the circadian rhythm in plasma melatonin were, examined in young males to obtain the threshold of light intensity for suppressing the nocturnal melatonin level on the one hand and to understand the relationship between the light-induced phase shift of melatonin rhythm and the melatonin suppression on the other hand. Eight subjects spent 3 days in an experimental living facility where light intensity was set below 200 lx and were exposed to light for 3 h in the early morning on the 2nd day. The same procedure was repeated five times in each subject with an interval of at least 3 wk, and one of five light intensities was tested in each trial. As a result, nocturnal melatonin level was not suppressed by light of 200 lx but significantly suppressed by light of intensity > or + 500 lx. On the other hand, the circadian melatonin rhythm was not shifted by any light intensity up to 10,000 lx. It is concluded that the threshold of light intensity for suppressing the melatonin level is located between 200 and 500 lx in young Japanese males, and the threshold for phase shifting the circadian melatonin rhythm was much greater than that for suppressing the nocturnal melatonin level in humans under entrained conditions.

Effect of radiant heat on head temperature gradient in term infants

AIMS

To test the hypothesis that external radiant heating might lead to significant fluctuations in superficial and core head temperatures in newborn infants.

METHODS

In an observation group of 14 term infants nursed under a radiant heater, servo-controlled to the abdominal skin, changes in rectal, core head, and scalp temperatures with heater activation were examined. In a further intervention group of six infants the effect of a reflective head shield on the fluctuations of scalp temperature was also tested.

RESULTS

In the observation group, when the heater had been off for 30 minutes, the rectal and scalp temperatures were 36.7 (SD 0.6) and 35.6 (0.6) degrees C, respectively, a difference of 1.2 (0.2) degrees C. After 30 minutes with the radiant heater on this fell to 0.2 (0.5) degrees C. The core head temperature, however, remained similar to the rectal temperature throughout. In the intervention group a reflective shield prevented the loss of the rectal-scalp gradient.

CONCLUSION

Overhead heater activation is associated with loss of the core to scalp temperature gradient, but no change in core head temperature in term infants. The clinical relevance of this superficial heating in vulnerable infants warrants further study.

Breathing, sleep state, and rectal temperature oscillations

Overheating may cause terminal apnoea and cot death. Rectal temperature and breathing patterns were examined in normal infants at home during the first 6 months of life. Twenty one infants had continuous overnight rectal temperature and breathing recordings for 429 nights (mean 20.4 nights, range 7-30) spaced over the first six months of life. Periods when breathing was 'regular' were directly marked on single night records. Sleep state was determined from respiratory variables. 'Regular' breathing was a reliable marker of 'quiet' sleep (specificity 93%). The duration of 'quiet' sleep increased from 6 to 22 minutes from two weeks to three months of age and then remained static, as did the proportion of sleep spent in the quiet phase (9% to 34%). Rectal temperature fell during 66% of quiet sleep and usually rose during rapid eye movement (REM) sleep. The drop in rectal temperature was maximal at the start of quiet sleep, whereas the maximum rise during REM sleep was reached after 10 to 15 minutes. Oscillations in rectal temperature are associated with changes in sleep and breathing state. The maturation of rectal temperature patterns during the first six months of life are closely related to a maturation of sleep state and breathing patterns.

[Non-photic entrainment of human circadian clock--effects of forced sleep-wake schedule on the circadian rhythm in plasma melatonin]

The present study was performed in order to have better understanding of the human circadian system. Two hypotheses concerning with the human circadian system have been advanced. One is a two self-sustained oscillator hypothesis, and the other is a two process hypothesis. Both hypotheses are based on a phenomenon called internal desynchronization. A major difference between the two hypothesis is that sleep or wakefulness does not affect the circadian oscillation in the two process hypothesis, while a mutual interaction between sleep (wakefulness) and the circadian oscillation is not excluded in the two oscillator hypothesis. On the other hand, social sues such as a sleep-wake schedule and regular contact with others have been considered as a major time cues (zeitgeber) for the human circadian rhythm. However, lights brighter than 5,000 lux was recently demonstrated to be capable of resetting the human circadian rhythm, and it is now a matter of debate whether the resetting effect of social cues is due to the light-dark cycle inevitably associated with a sleep-wake schedule. In the present study, the effects of forced sleep-wake schedules on the circadian rhythm in plasma melatonin and rectal temperature were examined in subjects under temporal isolation, which are not explained by the two process hypothesis. As a result, the forced sleep-wake schedule of 24.0-hour period in dim light condition (below 200 lux) entrained the circadian rhythms in 3 out of 8 subjects. The forced schedule in extremely dim light condition (below 5 lux) was also capable of entraining the circadian rhythm. On the other hand, the forced schedule of 23.5-hour period showed no entrainability. It is concluded that the non-photic entrainment is operating in the human circadian clock, which supports the two self-sustained oscillator hypothesis.

Periodic rectal motor activity: the intrinsic colonic gatekeeper?

BACKGROUND

Rectal motor activity is incompletely understood. The aim of this study was to characterize the patterns of rectal motor activity and to examine their diurnal variation and their relationships to proximal colonic activity and to meals.

METHODS

We performed a 30-h ambulatory motility study by recording pressure activity at multiple sites in the colon in 18 normal subjects.

RESULTS

During 288 h of recording, discrete bursts of tonic and phasic activity were seen in the rectum of all subjects at night and during the day lasting > or = 3 min, with a predominant frequency of 3 waves/min: periodic rectal motor activity (PRMA). Nocturnally, the number of cycles and the proportion of time occupied by this activity were greater (p < 0.001) and the inter-cycle interval was shorter (p < 0.008) compared with daytime, but the cycle duration was similar. Only 4 versus 5% (nocturnal vs daytime) of cycles propagated aborad, whereas 36 versus 14% (p < 0.01) propagated retrogradely, 16 versus 47% (p < 0.01) occurred simultaneously, and 44 versus 34% were confined to the rectum. There was considerable intra- and intersubject variability. PRMA was not related to meals or to anal motor activity, but 81% of nocturnal and 94% of daytime cycles occurred within 5 min of a motor event in the more proximal colon.

CONCLUSIONS

PRMA is a characteristic feature of the normal rectum and is more frequent at night. The temporal association with motor events in the proximal colon suggests that PRMA is triggered by the arrival of stool or gas in the rectum. Because most cycles are either segmental or are propagated retrogradely, PRMA may serve as an intrinsic braking mechanism that prevents untimely flow of colonic contents, particularly during sleep.

Anal canal cancer: current treatment and results

Combined radiation and chemotherapy is established as the preferred treatment for primary epidermoid cancer of the anal canal. This approach allows preservation of anorectal function without any apparent decrease in the survival rates obtained in the past with radical surgery. Most experience has been gained with radiation, 5-Fluorouracil (5-FU) and mitomycin C, but radiation, 5-FU and cisplatin are also effective. Regional lymph node metastases can be eradicated by radiation and chemotherapy, but cancers which have metastasized to regional nodes or to extrapelvic organs carry a poor prognosis. Extrapelvic metastases and recurrent pelvic cancer respond poorly to systemic chemotherapy, and to combinations of radiation and chemotherapy. Cisplatin combined with 5-FU is the most effective treatment presently available in such situations. No effective systemic adjuvant therapy has yet been devised.

Monitoring body-core temperature from the trachea: comparison between pulmonary artery, tympanic, esophageal, and rectal temperatures

INTRODUCTION

We designed an endotracheal tube (ETT) for acquiring body-core temperature from the trachea. This ETT had two temperature sensors, one attached to the inside surface of the cuff, the other mounted on the ETT shaft underneath the cuff. The ETT was evaluated in vitro and in dogs to determine: 1) optimal position of temperature sensors and 2) the responsiveness, accuracy, and resistance to ventilatory artifacts.

METHODS

In vitro. An artificial trachea assessed the response-time and accuracy of ETT temperature sensors to abrupt temperature changes and ventilatory flow-rates. In vivo. Body temperature in 5 dogs was lowered to approximately 26 degrees C then elevated toward 39 degrees C using a heat exchanger during carotid-jugular bypass. ETT temperature measurements were compared simultaneously with those from the artificial trachea (in vitro) or from the pulmonary artery, tympanic cavity, esophagus, and rectum of dogs using dry and humidified gas.

RESULTS

Cuff temperature sensor responded quickly and accurately to temperature changes and was less prone than the tube sensor to ventilatory and humidity artifacts. During carotid-jugular bypass, in vivo tube and cuff mean temperatures averaged 1.4 degrees C and 0.36 degree C lower, respectively, than pulmonary artery temperatures. There were no statistical differences (P > 0.05) between cuff temperatures and those measured from the pulmonary artery, tympanic cavity, esophagus, and rectum. Heating and humidifying the inspiratory gas of dogs with a water-bath humidifer or heat moisture exchanger (HME) had minimal effects on the cuff temperature sensor. An in-line HME increased in vivo tube temperature from baseline values by 1.13 +/- 0.80 degree C, while cuff temperature increased by 0.21 +/- 0.24 degree C.

CONCLUSION

The cuff of the ETT is a reliable site for measuring body-core temperature in intubated patients.