Blood flow rate in arteriovenous anastomoses: from the cradle to the grave

Choroidal arteriovenous anastomoses: a hypothesis for the pathogenesis of central serous chorioretinopathy and other pachychoroid disease spectrum abnormalities

The pachychoroid disease spectrum (PDS) includes several chorioretinal diseases that share specific choroidal abnormalities. Although their pathophysiological basis is poorly understood, diseases that are part of the PDS have been hypothesized to be the result of venous congestion. Within the PDS, central serous chorioretinopathy is the most common condition associated with vision loss, due to an accumulation of subretinal fluid in the macula. Central serous chorioretinopathy is characterized by distinct risk factors, most notably a high prevalence in males and exposure to corticosteroids. Interestingly, sex differences and corticosteroids are also strongly associated with specific types of arteriovenous anastomoses in the human body, including dural arteriovenous fistula and surgically created arteriovenous shunts. In this manuscript, we assess the potential of such arteriovenous anastomoses in the choroid as a causal mechanism of the PDS. We propose how this may provide a novel unifying concept on the pathophysiological basis of the PDS, and present cases in which this mechanism may play a role.

Skin Temperatures of Back or Neck Are Better Than Abdomen for Indication of Average Proximal Skin Temperature During Sleep of School-Aged Children

PURPOSE

The tight association between sleep, body temperature regulation, and patterns of skin temperature change highlights the necessity for accurate and valid assessment of skin temperatures during sleep. With increased interest in this functional relationship in infants and children, it is important to identify where to best measure proximal skin temperature and whether it is possible to reduce the number of sites of measures, in order to limit the experimental effects in natural settings. Thus, the aim of this study was to determine the most suitable single skin temperature sites for representation of average proximal skin temperature during sleep of school aged children.

METHODS

Statistical analyses were applied to skin temperature data of 22 children, aged 6 to 12 years, measured over four consecutive school nights in their home settings, to compare single site measures of abdomen, back, neck, forehead and subclavicular skin temperatures (local temperatures) with average proximal skin temperatures.

RESULTS

Abdomen and forehead skin temperatures were significantly different (respectively higher and lower) to the other local proximal temperatures and to average proximal skin temperatures. Moreover, the time pattern of forehead temperature was very different from that of the other local temperatures.

CONCLUSIONS

Local forehead and abdomen skin temperatures are least suitable as single site representations of average proximal skin temperatures in school aged children when considering both the level and the time course pattern of the temperature across the night. Conversely, back and neck temperatures provide most fitting representation of average proximal skin temperatures.

Sleep and Skin Temperature in Preschool Children and Their Mothers

The purpose of this study was to investigate and compare sleep and skin temperature (Tsk) of preschool children with those of their mothers. The subjects included 18 pairs of preschool children and their mothers. The actigraphic measurement of sleep, Tsk, heart rate, bedroom climate, and the microclimate temperature and humidity (bed climate) were measured. Proximal and distal Tsk, the temperature gradient of distal and proximal Tsk (DPG), and bed climate temperature were significantly lower in the children. Approximately 70% of the children slept without bed covering. Heat dissipation during sleep in preschool children may primarily rely on the proximal Tsk. The lower Tsk than adults, and behavioral thermoregulation, may be important for sleep in preschoolers.

Chilblains in Turkey: a case-control study

BACKGROUND

Chilblains are rather common in winter months in our country.

OBJECTIVES

Determination of demographical and clinical characteristics of patients presenting with chilblains in Diyarbakir, Turkey. Evaluation of body mass index (BMI) as risk factor for development of chilblains.

METHODS

Sixty-nine patients who were diagnosed as chilblains at our outpatient clinics were included in this study. No exclusion criteria were sought. Demographical data including height and weight and answers to questions related to personal history were recorded. A control group consisting of 108 controls were chosen from among patients presenting with complaints of hair loss. Statistical analyses were conducted using SPSS 17.0.

RESULTS

Of the 69 patients with chilblains, 45 (65.2%) were females and 24 (34.8%) were males. Mean age (± SD) of the patients was 21 ± 9. 71.2% of the patients complained of itching, 51.6% of pain, 31.3% of burning in the lesions. 61.3% of the patients reported recurrence of the lesions every winter season. Mean BMI of the patients was 20.5 ± 2.9. Mean BMI of the controls was 22.4 ± 3.7 and the difference was statistically significant (p=0.01).

CONCLUSIONS

Low BMI may be a risk factor contributing to development of chilblains in persons exposed to cold weather conditions. Apart from external factors, there seems to be a personal tendency to develop lesions, as many patients report recurrences every year. Diagnosis of chilblains requires wariness, as history of cold exposure may not be evident.

Does comprilan bandage have any influence on peripheral perfusion in patients with oedema?

AIM

Comprilan bandage may be an attractive treatment of leg oedema, but theoretically bandage could compromise peripheral circulation. The present study was undertaken to investigate circulation in the first toe before, during, and after treatment with comprilan bandage.

METHODS AND STUDY POPULATION

Blood flow rate was measured by the heat-washout method in the pulp of the first toe of 10 patients (eight women, two men, aged 75-94) with leg oedemas, and systolic toe blood pressure was determined by the strain gauge method. Oedema was scored according to a visual scale, and the patients were treated with comprilan (short stretch) bandage for 1 week. Toe blood flow rate was measured before, during and after the use of the bandages, and toe blood pressure was measured before and after the use of bandages.

RESULTS

According to the visual scale, all subject benefited from the treatment by reduction of oedema, and they reported increased well-being after. Blood flow rate was not significantly altered during and after the treatment. Systolic toe pressure was normal in all patients (R/L = 94/83 mmHg), and no significant change took place during and after the use of the bandages (92/90 mmHg).

CONCLUSION

Comprilan bandage has a positive effect on legs oedemas, visually as well as according to the patients well-being. The treatment does not have any significant influence on toe blood pressure. It cannot, however, be excluded that the use of comprilan bandage may compromise toe blood flow rate slightly (<5%). A larger study with more subjects has to be made to come this closer, and additional capillary blood flow rate should be measured in an area without arteriovenous anastomoses.

Supraorbital cutaneous blood flow rate during carotid endarterectomy

BACKGROUND

The supraorbital skin region is supplied by the supraorbital artery, which is a branch of the internal carotid artery. The supraorbital cutaneous blood flow rate may therefore be influenced by changes in the internal carotid artery flow during carotid endarterectomy.

METHODS

The supraorbital cutaneous blood flow rate was measured by the application of heat to the skin and following the subsequent dissipation of the heat in seven patients undergoing carotid endarterectomy. At the same time, the oxygenation in the right and left frontal region was monitored by near-infrared spectroscopy (NIRS).

RESULTS

During cross-clamping of the carotid artery, the ipsilateral NIRS-determined frontal oxygenation tended to decrease [67 +/- 13% to 61 +/- 11% (P = 0.06); contralateral 68 +/- 11% to 66 +/- 8%] as did the supraorbital cutaneous blood flow rate from 56 +/- 23 to 44 +/- 7 ml 100 g(-1) min(-1). With the opening of the external carotid artery, the NIRS-determined frontal oxygenation reversed to 66 +/- 8% (P<0.05) on the ipsilateral side, with no significant change on the contralateral side and the supraorbital cutaneous blood flow rate increased to 53 +/- 11 (P<0.05). Opening of the internal carotid artery did not significantly affect the NIRS (67 +/- 8% and 69 +/- 9%; ipsilateral, contralateral), but the supraorbital cutaneous blood flow rate increased to 88 +/- 10 ml 100 g(-1) min(-1) (P<0.001).

CONCLUSION

Cross-clamping of the internal carotid artery affects the supraorbital cutaneous blood flow rate as well as the frontal lobe oxygenation.

Effect of a short period of abstinence from smoking on rewarming patterns of the hands following local cooling

The purpose of the study was to examine the effect of a 12 h period of abstinence from smoking in young and old habitual smokers, on skin rewarming patterns of a hand following local cooling. This was done by comparing changes in peripheral circulation, measured indirectly by monitoring changes in skin surface temperatures of the hand with both infrared (IR) thermography and thermocouples before, during and after immersing the right hand for 2 min in water at 10 degrees C. Included in the study were young male non-smokers (n = 14) and smokers (n = 13), and elderly non-smokers (n = 12) and smokers (n = 14). The results showed no statistically significant difference between young non-smokers and smokers when comparing their response to the local cold challenge. The elderly smokers had a significantly higher hand skin temperature prior to cooling (34.0 +/- 0.2 degrees C) and after 80% rewarming (32.1 +/- 0.2 degrees C) (i.e. when the skin temperature in the "cooled" hand has regained 80% of the cold induced drop in temperature), compared to elderly non-smokers (33.3 +/- 0.2 and 31.3 +/- 0.2 degrees C, respectively). The elderly smoking subjects also had a faster recovery after cooling (9.7 +/- 0.8 min) than the elderly non-smoking subjects (16.7 +/- 2.6 min). A follow-up study with seven elderly smokers, who had smoked as usual until 2 h before the experiment, showed responses lying between the non-smokers and smokers who had had a longer period of abstinence (12 h) from smoking. In conclusion, we have demonstrated using IR-thermal imaging that elderly subjects who have smoked for many years have slightly warmer hand skin temperature when they abstain from smoking. Even a period of abstinence from smoking of a few hours can affect the way in which elderly subjects respond to a local cold challenge, recovering more rapidly then their non-smoking counterparts.