Microcirculatory assessment in perioperative and critically ill patients

Bedside microcirculatory monitoring in surgical and critically ill patients was assessed in this thesis, to address the potential clinical feasibility and value of the handheld vital microscope (HVM) imaging. Different organ surfaces were investigated and explored using HVM imaging, in the sublingual space as well in distant organs as the liver, intestines and the peritoneum. Four different areas of investigation were targeted; 1) assessment of the microcirculatory leukocytes, 2) fluid management in the perioperative phase, 3) liver perfusion during liver resection, 4) morphological assessment of organ microcirculation in health and disease.
Microcirculatory monitoring by HVM is applied in cardiac surgery, liver surgery, in volunteer and rabbit studies. The following novel insights regarding the microcirculatory monitoring were revealed:
- Eye-balling is a possible observational evaluation to identify alterations in the microcirculation, especially when measured in one spot over a long period.
- New methodology has become available to identify microcirculatory leukocytes using the space-time diagram by HVM.
- The microvascular density should be used as a target parameter during fluid management.
- Hepatic microcirculatory changes occur during the atrophy-hypertrophy complex induced by portal vein embolization and during vascular inflow occlusion.
- Introduction of a new anatomy guided sublingual microcirculatory assessment using HVM.
The first steps are made in this thesis towards clinical use of HVM. However, future research needs to establish and validate these introduced microvascular parameters. There is a need for clearly defined targets as well as interventions targeting the microcirculation.