Why Rudolph's nose is red: Observational study

Objective: To characterise the functional morphology of the nasal microcirculation in humans in comparison with reindeer as a means of testing the hypothesis that the luminous red nose of Rudolph, one of the most well known reindeer pulling Santa Claus's sleigh, is due to the presence of a highly dense and rich nasal microcirculation. Design: Observational study. Setting: Tromsø, Norway (near the North Pole), and Amsterdam, the Netherlands. Participants: Five healthy human volunteers, two adult reindeer, and a patient with grade 3 nasal polyposis. Main outcome measures: Architecture of the microvasculature of the nasal septal mucosa and head of the inferior turbinates, kinetics of red blood cells, and real time reactivity of the microcirculation to topical medicines. Results: Similarities between human and reindeer nasal microcirculation were uncovered. Hairpin-like capillaries in the reindeers' nasal septal mucosa were rich in red blood cells, with a perfused vessel density of 20 (SD 0.7) mm/mm2. Scattered crypt or gland-like structures surrounded by capillaries containing flowing red blood cells were found in human and reindeer noses. In a healthy volunteer, nasal microvascular reactivity was demonstrated by the application of a local anaesthetic with vasoconstrictor activity, which resulted in direct cessation of capillary blood flow. Abnormal microvasculature was observed in the patient with nasal polyposis. Conclusions: The nasal microcirculation of reindeer is richly vascularised, with a vascular density 25% higher than that in humans. These results highlight the intrinsic physiological properties of Rudolph's legendary luminous red nose, which help to protect it from freezing during sleigh rides and to regulate the temperature of the reindeer's brain, factors essential for flying reindeer pulling Santa Claus's sleigh under extreme temperatures

Intraoperative Imaging Techniques to Visualize Hepatic (Micro)Perfusion: An Overview

The microcirculation plays a crucial role in the distribution of perfusion to organs. Studies have shown that microcirculatory dysfunction is an independent predictor of morbidity and mortality. Hence, ass

Imaging sublingual microcirculatory perfusion in pediatric patients receiving procedural sedation with propofol: A pilot study

Objective: Procedural sedation with propofol is widely used in the pediatric population. A well-known side effect of propofol is a decrease in peripheral vascular resistance resulting in hypotension, but little is known about the effects on microcirculation in humans. We aimed to evaluate the effects of propofol on the sublingual microcirculatory perfusion by continuous video imaging in pediatric patients undergoing procedural sedation. Methods: Patients admitted to the Pediatric Intensive Care Unit for procedural sedation were recruited. Oral microcirculation was measured employing a continuous monitoring strategy with incident dark-field illumination imaging. Measurements were obtained before and 3 minutes after propofol induction. Total and perfused vessel densities, proportion of perfused vessels, microvascular flow index, blood vessel diameter (Øbv), and systemic hemodynamics were analyzed. Results: Continuous measurements were achieved in seven patients. Three minutes after propofol induction mean arterial pressure decreased (P = 0.028) and total and perfused vessel densities increased by 12% (P = 0.018) and 16% (P = 0.018), respectively. MFI was unaltered and mean Øbv increased but not significantly. Conclusions: Propofol induction induces a reduction in mean arterial pressure and a rise in sublingual microvascular perfusion. The observed effects of propofol on the sublingual microcirculation may be due to a decrease in microvascular resistance

Intravital sidestream dark-field (SDF) imaging is used in a rabbit model for continuous noninvasive monitoring and quantification of mucosal capillary regeneration during wound healing in the oral cavity: a pilot study

Angiogenesis and tissue revascularization are essential for proper postoperative tissue repair and regeneration. The aim of this investigation was to develop an animal model to study postoperative microcirculatory vascularization continuously in time following oral surgery. Five female specific-pathogen free New Zealand White rabbits with a mean body weight of 3.0 ± 0.4 kg were used in this study. In all animals a palatine mucosal flap was raised, suspended for 30 min, and then repositioned for subsequent postoperative assessment of capillary regeneration. Noninvasive mucosal capillary density measurements were performed preoperatively using sidestream dark-field (SDF) imaging and repeated measurements were collected immediately postoperatively and on days 2, 4, 7, 9, 11, 14, and 21. In addition, whole blood count (Hb, RBC, WBC, PLT) and body weight were monitored in all animals at each time point. The greatest increase in mucosal capillary regeneration occurred in the early healing period on days 4, 7, 9, and recovery to baseline was achieved by postoperative day 11. Comparisons between preoperative versus postoperative, and prospective mean capillary density measurements on days 2, 4, 7, and 9 were statistically significant (P < 0.05). No significant difference in capillary density development at each time point was observed between the five animals. In all animals, whole blood count and body weight remained stable and revealed no statistically significant changes. However, only on day 21 a statistically significant increase in body weight was found (P < 0.05). The application of SDF imaging in the present wound model enabled continuous daily inspection of the oral microcirculation following surgery in vivo to pursue the kinetics of microcirculatory regeneration in time. We expect SDF imaging and our wound model to contribute to new insights into the kinetics of wound vascularization under various pathophysiological conditions and drug intervention studies