Keshen R. Mathura

Nitroglycerin in septic shock after intravascular volume resuscitation

In patients with septic shock, oxygen consumption is increased, but oxygen delivery and extraction is impaired, partly because of microcirculatory shutdown and shunting. Orthogonal polarisation spectral (OPS) imaging allows visualisation of the microcirculation. We used this technique to assess microcirculatory flow in septic-shock patients who had a mean arterial blood pressure of more than 60 mm Hg and central venous pressure greater than 12 mm Hg. The infusion of 0.5 mg of nitroglycerin intravenously then resulted in a marked increase in microvascular flow on OPS imaging. Improved recruitment of the microcirculation could be a new resuscitation endpoint in septic shock.

Abnormal microcirculation in brain tumours during surgery

Orthogonal Polarisation Spectral imaging is a new clinical technique that uses polarised light to visualise the microcirculation of organ surfaces. We have used this technique to compare the functional microcirculatory properties of three types of brain tumour with those of the normal cortex. Meningiomas were characterised by chaotic and dilated vessels with almost no erythrocyte movement and a dark background, glioblastoma by few vessels with low flow and a background close to that of the healthy cortex, and metastases by a very dark background, almost no flow, and a chaotic vascular pattern. This technique could provide useful information about microcirculatory morphology and kinetics for diagnostic use during neurosurgery.

Impaired vascular function in women with pre‐eclampsia observed with orthogonal polarisation spectral imaging

Objective To investigate in vivo the function of the microcirculation of the skin in pregnancy and pregnancy complicated with pre‐eclampsia.

The temporal course of mucoperiosteal flap revascularization at guided bone regeneration-treated implant sites: a pilot study

AIMS To investigate post-operative capillary density regeneration in healing mucoperiosteal flaps at guided bone regeneration-treated implant sites. MATERIAL AND METHODS A non-invasive post-operative investigation was performed in 10 patients using orthogonal polarization spectral (OPS) imaging for assessment of capillary density during the course of mucoperiosteal flap wound healing for 6 weeks in patients receiving dental implants. RESULTS The greatest increase in capillary regeneration occurred in the early wound-healing phase, during weeks 1 and 2, and recovery to baseline was achieved between weeks 4 and 5. A comparison of adjacent OPS measurements indicated that differences between the time point immediately following administration of local anaesthesia and directly post-operatively ( p=0.002), between a directly post-operative time point and after 1 week (p=0.009), and between post-operative weeks 1 and 2 (p=0.036) were statistically significant. CONCLUSIONS The early healing phase of mucoperiosteal flaps is characterized by rapid capillary regeneration. OPS imaging enabled the possibility to monitor and quantify the temporal development of mucoperiosteal flap revascularization following periodontal surgery.

Microvascular soft tissue changes in alveolar distraction osteogenesis

OBJECTIVE The aim of the study was to quantify the effect of distraction osteogenesis on the changes in vascular density in the human oral mucosa. MATERIAL AND METHODS Alveolar distraction was performed in 10 patients with alveolar ridge deficiencies, while in the contralateral nondistracted site an implant was placed. The distraction device was activated after 7 days of latency starting with a distraction rate of 1 mm a day for a 1-week period. After completion of distraction the segments were held in fixation for 6 weeks. Microvascular images were obtained with the use of orthogonal polarization spectral imaging. From day 1 postoperatively until the end of consolidation, microvascular changes in capillary density were assessed. RESULTS All patients had a good response to the osseous distraction. No dehiscence or infections were observed. In all patients microvascular changes consisted of a bilateral decrease in capillary density and capillary index immediately following surgery. No significant differences between the distraction site and nondistracted implant site were observed during the latency phase or consolidation phase. Capillary vessel count revealed a mean of 14.6 +/- 2.7 vessels per visual field (VF) at day 5 of distraction versus 16.6 +/- 2.9 vessels/VF in the nondistracted site, which increased to a mean of 33.4 +/- 4.0 vessels/VF at day 10 of distraction compared to 24.0 +/- 0.8 vessels/VF in nondistracted implant sites. During the consolidation period the mean number of vessels was comparable to preoperative levels (mean 26.0 vessels/VF). The increase in capillary density and capillary index was more pronounced during the activation phase of distraction compared to the implant site. CONCLUSION The increase in vascular response during distraction osteogenesis mainly occurs in the activation phase of distraction.