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

Sedation with propofol and isoflurane differs in terms of microcirculatory parameters: A randomized animal study using dorsal skinfold chamber mouse model

OBJECTIVE

This study aimed to explore the effects of sedative doses of propofol and isoflurane on microcirculation in septic mice compared to controls. Isoflurane, known for its potential as a sedation drug in bedside applications, lacks clarity regarding its impact on the microcirculation system. The hypothesis was that propofol would exert a more pronounced influence on the microvascular flow index, particularly amplified in septic conditions.

MATERIAL AND METHODS

Randomized study was conducted from December 2020 to October 2021 involved 60 BALB/c mice, with 52 mice analyzed. Dorsal skinfold chambers were implanted, followed by intraperitoneal injections of either sterile 0.9 % saline or lipopolysaccharide for the control and sepsis groups, respectively. Both groups received propofol or isoflurane treatment for 120 min. Microcirculatory parameters were obtained via incident dark-field microscopy videos, along with the mean blood pressure and heart rate at three time points: before sedation (T0), 30 min after sedation (T30), and 120 min after sedation (T120). Endothelial glycocalyx thickness and syndecan-1 concentration were also analyzed.

RESULTS

In healthy controls, both anesthetics reduced blood pressure. However, propofol maintained microvascular flow, differing significantly from isoflurane at T120 (propofol, 2.8 ± 0.3 vs. isoflurane, 1.6 ± 0.9; P < 0.001). In the sepsis group, a similar pattern occurred at T120 without statistical significance (propofol, 1.8 ± 1.1 vs. isoflurane, 1.2 ± 0.7; P = 0.023). Syndecan-1 levels did not differ between agents, but glycocalyx thickness index was significantly lower in the isoflurane-sepsis group than propofol (P = 0.001).

CONCLUSIONS

Propofol potentially offers protective action against microvascular flow deterioration compared to isoflurane, observed in control mice. Furthermore, a lower degree of sepsis-induced glycocalyx degradation was evident with propofol compared to isoflurane.

Hemodynamics of the oral mucosa during cooling: A crossover clinical trial

Objective

Oral cryotherapy is used to prevent the onset of oral mucositis, a common and debilitating adverse effect following cancer chemotherapy. A protective mechanism associated with oral cooling is thought to be mediated through reduced tissue microcirculation. The aim of the present study was to examine the underlying mechanism associated with oral mucosal cooling by measuring oral microcirculation and tissue oxygen saturation after cooling with ice chips (IC) and an intraoral cooling device (ICD).

Study design

In a single-center randomized crossover study, 10 healthy volunteers were assigned (1:1) randomly to the order in which the two intraoral cooling procedures (IC/ICD) were to be commenced. On day 1, half of the study participants started with IC and then crossed over to intraoral cooling with the ICD on day 2, while the other half of the participants undertook the same two procedures in the reverse order. Total and functional capillary density (T/FCD) and tissue oxygen saturation (StO2) measurements were obtained at baseline and 30 min following oral cooling.

Results

Following 30 min of oral cooling, a statistically significant difference was found for FCD between IC and ICD (percentage points; +2 vs. -13; p < 0.05). A statistically significant decrease in StO2 was observed with both IC and ICD (%; 13 vs. 10) after 30 min of cooling as compared to baseline (p < 0.05). As for the participants' preference the ICD was preferred over IC by 9 out of 10 participants (p = 0.021).

Conclusions

Both microcirculation parameters and tissue oxygen saturation are altered in conjunction with oral cooling, indicating their potential mechanistic contribution towards cryoprevention of oral mucositis.

Identifying a sublingual triangle as the ideal site for assessment of sublingual microcirculation

The sublingual mucosa is a commonly used intraoral location for identifying microcirculatory alterations using handheld vital microscopes (HVMs). The anatomic description of the sublingual cave and its related training have not been adequately introduced. The aim of this study was to introduce anatomy guided sublingual microcirculatory assessment. Measurements were acquired from the floor of the mouth using incident dark-field (IDF) imaging before (T0) and after (T1) sublingual cave anatomy instructed training. Instructions consists of examining a specific region of interested identified through observable anatomical structures adjacent and bilaterally to the lingual frenulum which is next to the sublingual papilla. The anatomical location called the sublingual triangle, was identified as stationed between the lingual frenulum, the sublingual fold and ventrally to the tongue. Small, large, and total vessel density datasets (SVD, LVD and TVD respectively) obtained by non-instructed and instructed measurements (NIN (T0) and IM (T1) respectively) were compared. Microvascular structures were analyzed, and the presence of salivary duct-related microcirculation was identified. A total of 72 video clips were used for analysis in which TVD, but not LVD and SVD, was higher in IM compared to NIM (NIM vs. IM, 25 ± 2 vs. 27 ± 3 mm/mm2 (p = 0.044), LVD NIM vs. IM: 7 ± 1 vs. 8 ± 1mm/mm2 (p = 0.092), SVD NIM vs. IM: 18 ± 2 vs. 20 ± 3 mm/mm2 (p = 0.103)). IM resulted in microcirculatory assessments which included morphological properties such as capillaries, venules and arterioles, without salivary duct-associated microcirculation. The sublingual triangle identified in this study showed consistent network-based microcirculation, without interference from microcirculation associated with specialized anatomic structures. These findings suggest that the sublingual triangle, an anatomy guided location, yielded sublingual based measurements that conforms with international guidelines. IM showed higher TVD values, and future studies are needed with larger sample sizes to prove differences in microcirculatory parameters.

Incidence of Adverse Effects of Propofol for Procedural Sedation/Anesthesia in the Pediatric Emergency Population: A Systematic Review and Meta-Analysis

BACKGROUND

To investigate the incidence of adverse effects of propofol among pediatric population for sedation or anesthesia.

METHODS

We performed Cochrane Library, PubMed, CNKI, VIP, and Wanfang databases to research relevant literature. We did sensitivity analysis to assess the incidence of adverse effects of propofol among pediatric population for sedation or anesthesia.

RESULTS

In 132 studies, eight RCTs were included in this analysis. The result showed that adverse events (bradypnea, hypotension, hypertension, and apnea) were significantly improved in the pediatric emergency population in the propofol group, but it had no effect on the incidence of cough attacks, desaturation, agitation, stridor, and laryngospasm. Furthermore, the subgroup analysis showed that those who received propofol for had decreased adverse effects compared with the patients who received ketamine treatment (SMD = 0.44, 95%CI = [0.28, 0.67], I 2 = 0%, and P = 0.0002), which demonstrated that propofol could decrease the incidence of adverse effects compared with ketamine and ketofol.

CONCLUSIONS

The study demonstrated that propofol may decrease the incidence of bradypnea, hypotension, hypertension, and apnea, but it had no effect on the incidence of cough attacks, desaturation, agitation, stridor, and laryngospasm. Furthermore, more large RCTs are needed to assess incidence of adverse effects of propofol among pediatric population.

Microcirculatory Changes in Pediatric Patients During Congenital Heart Defect Corrective Surgery

A prospective, observational single-center study was carried out. Pediatric patients undergoing congenital heart defect surgery were evaluated before, during, and after surgery. At each time point, sublingual microcirculation and clinical parameters were assessed, along with analytical variables. Twenty-four patients were included. All microcirculatory parameters worsened during cardiopulmonary bypass and returned to baseline values after surgery (p ≤ 0.001). In the intraoperative evaluation, body temperature correlated with perfused small vessel density (p = 0.014), proportion of perfused small vessels (p < 0.001), small vessel microvascular flow index (p = 0.003), and small vessel heterogeneity index (p < 0.002). Patients with cyanotic disease exhibited higher small vessel density (p < 0.008) and higher density of perfused small vessels (p < 0.022) at baseline, and a lower microvascular flow index (p = 0.022) and higher heterogeneity (p = 0.026) in the intraoperative phase. Children with congenital heart disease exhibited decreased vascular density and microvascular blood flow and increased heterogeneity during cardiopulmonary bypass. All these parameters returned to baseline values after surgery.

Microcirculatory Differences in Children With Congenital Heart Disease According to Cyanosis and Age

Background: Congenital heart disease (CHD) is one of the main causes of morbidity and mortality in children. Microcirculatory changes in CHD patients have previously been investigated using a variety of techniques. Handheld videomicroscopy enables non-invasive direct visualization of the microcirculatory bed. The aim of our study was to determine if there are microcirculatory differences among CHD patients based on age and the presence of cyanosis. Methods: A prospective observational study was carried out. Patients with CHD undergoing corrective surgery were evaluated after anesthetic induction prior to surgery. Microcirculation was evaluated using sidestream dark field (SDF) imaging. Hemodynamics and respiratory, biochemical, and tissue perfusion parameters were analyzed. Results: A total of 30 patients were included, of whom 14 were classified as cyanotic and 16 as non-cyanotic. Cyanotic patients had a higher total vessel density (TVD) (p = 0.016), small vessel density (p = 0.004), and perfused small vessel density (p = 0.013), while their microvascular flow index (MFI) was lower (p = 0.013). After adjustment for age and PaO₂, cyanotic patients showed increased TVD (p = 0.023), and small vessel density (p = 0.025) compared to non-cyanotic patients but there were no differences on the MFI. Age was directly correlated with total MFI (spearman's rho = 0.499, p = 0.005) and small vessel MFI (spearman's rho = 0.420, p = 0.021). After adjustment for the type of CHD (cyanotic vs. non-cyanotic) patients with MFI and small MFI vessels <3 were younger than those with values ≥3 (p = 0.033 and p = 0.037). Conclusions: SDF-based evaluation of microcirculation in CHD patients showed that patients with cyanotic defects had higher vascular density, as compared to patients with non-cyanotic defects. Younger patients were more likely to have a low MFI regardless of their type of CHD.

Assessing the Microcirculation With Handheld Vital Microscopy in Critically Ill Neonates and Children: Evolution of the Technique and Its Potential for Critical Care

Assuring adequate tissue oxygenation in the critically ill, but still developing child is challenging. Conventional hemodynamic monitoring techniques fall short in assessing tissue oxygenation as these are directed at the macrocirculation and indirect surrogates of tissue oxygenation. The introduction of handheld vital microscopy (HVM) has allowed for the direct visualization of the microcirculation and with this has offered insight into tissue oxygenation on a microcirculatory level. Since its introduction, technical improvements have been made to HVM, to both hardware and software, and guidelines have been developed through expert consensus on image assessment and analysis. Using HVM, the microcirculation of the skin, the buccal mucosa, and the sublingual mucosa of healthy and (critically) ill neonates and children have been visualized and investigated. Yet, integration of HVM in hemodynamic monitoring has been limited due to technical shortcomings. Only superficial microcirculatory beds can be visualized, inter-observer and intra-observer variabilities are not accounted for and image analysis happens offline and is semi-automated and time-consuming. More importantly, patients need to be cooperative or fully sedated to prevent pressure and movement artifacts, which is often not the case in children. Despite these shortcomings, observational research with HVM in neonates and children has revealed the following: (1) age-related developmental changes in the microcirculation, (2) loss of hemodynamic coherence, i.e., microcirculatory disturbances in the presence of a normal macrocirculation and, (3) microcirculatory disturbances which were independently associated with increased mortality risk. Although these observations underline the importance of microcirculatory monitoring, several steps have to be taken before integration in the decision process during critical care can happen. These steps include technological innovations to ease the use of HVM in the pediatric age group, measuring additional functional parameters of microvascular blood flow and integrated automated analysis software. As a next step, reference values for microcirculatory parameters need to be established, while also accounting for developmental changes. Finally, studies on microcirculatory guided therapies are necessary to assess whether the integration of microcirculatory monitoring will actually improve patient outcome. Nevertheless, HVM remains a promising, non-invasive tool to help physicians assure tissue oxygenation in the critically ill child.

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 (Ø_bv), 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 Ø_bv 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.