Intravenous nitroglycerin does not preserve gastric microcirculation during gastric tube reconstruction: a randomized controlled trial

The impact of nitroglycerine and volume on gastric tube microperfusion assessed by indocyanine green fluorescence imaging

The influence of hypervolemia and intraoperative administration of nitroglycerine on gastric tube microperfusion remains unclear The present study aimed to investigate the impact of different hemodynamic settings on gastric tube microperfusion quantified by fluorescence imaging with Indocyanine green (ICG-FI) as a promising tool for perfusion evaluation. Three groups with seven pigs each were formed using noradrenaline, nitroglycerin, and hypervolemia for hemodynamic management, respectively. ICG-FI, hemodynamic parameters, and transit-time flow measurement (TTFM) in the right gastroepiploic artery were continuously assessed. Fluorescent microspheres (FM) were administered, and the partial pressure of tissue oxygen was quantified. The administration of nitroglycerine and hypervolemia were both associated with significantly impaired microperfusion compared to the noradrenaline group quantified by ICG-FI. Even the most minor differences in microperfusion could be sufficiently predicted which, however, could not be represented by the mean arterial pressure measurement. Histopathological findings supported these results with a higher degree of epithelial damage in areas with impaired perfusion. The values measured by ICG-FI significantly correlated with the FM measurement. Using tissue oxygenation and TTFM for perfusion measurement, changes in microperfusion could not be comprehended. Our results support current clinical practice with restrictive volume and catecholamine administration in major surgery. Hypervolemia and continuous administration of nitroglycerine should be avoided.

Use of vasopressors during esophagectomy is not associated with increased risk of anastomotic leak

Vasopressor use during esophagectomy has been reported to increase the risk of postoperative anastomotic leak and associated morbidity. We sought to assess the association between vasopressor use and fluid (crystalloid and colloid) administration and anastomotic leak following open esophagectomy. Patients who underwent open Ivor Lewis esophagectomy were identified from a prospective institutional database. The primary outcome was postoperative anastomotic leak (any grade) and analyzed using logistic regression models. Postoperative anastomotic leak developed in 52 of 327 consecutive patients (16%) and was not significantly associated with vasopressor use or fluid administered in either univariable or multivariable analyses. Increasing body mass index was the only significant characteristic of both univariable (P = 0.004) and multivariable analyses associated with anastomotic leak (odds ratio, 1.05; 95% confidence interval, 1.01-1.09; P = 0.007). Of the 52 patients that developed an anastomotic leak, 12 (23%) were grade 1, 21 (40%) were grade 2 and 19 (37%) were grade 3. In our cohort, only body mass index, and not intraoperative vasopressor use and fluid administration, was significantly associated with increased odds of postoperative anastomotic leak following open Ivor Lewis esophagectomy.

Manipulating the Microcirculation in Sepsis - the Impact of Vasoactive Medications on Microcirculatory Blood Flow: A Systematic Review

BACKGROUND

Sepsis is life-threatening organ dysfunction because of a dysregulated host response to infection. Disturbed microvascular blood flow is associated with excess mortality and is a potential future target for interventions. This review addresses the evidence for pharmacological manipulation of the microcirculation in sepsis assessed by techniques that evaluate the sublingual microvasculature.

METHODS

Systematic review using a published protocol. Eligibility criteria were studies of septic patients published from January 2000 to February 2018. Interventions were drugs aimed at improving perfusion. Outcome was improvement in microvascular flow using orthogonal polarization spectral, sidestream dark field, or incident dark field imaging (Grades of Recommendation, Assessment, Development, and Evaluation criteria used).

RESULTS

Two thousand six hundred and six articles were screened and 22 included. (6 randomized controlled trials, 12 interventional, 3 observational, and 1 pilot, n = 572 participants). Multiple measurement techniques were described, including: automated analyses, subjective, and composite scoring systems. Norepinephrine was not found to improve microvascular flow (low-grade evidence, n = 6 studies); except in chronic hypertension (low, n = 1 study). Addition of arginine vasopressin or terlipressin to norepinephrine maintained flow while decreasing norepinephrine requirements (high, n = 2 studies). Neither dobutamine nor glyceryl trinitrate consistently improved flow (low, n = 6 studies). A single study (n = 40 participants) demonstrated improved flow with levosimendan (high). In a risk of bias assessment 16/16 interventional, pilot and observational studies were found to be high risk.

CONCLUSIONS

There is no robust evidence to date that any one agent can reproducibly lead to improved microvascular flow. Furthermore, no study demonstrated outcome benefit of one therapeutic agent over another. Updated consensus guidelines could improve comparable reporting of measurements and reduce bias, to enable meaningful comparisons around the effects of individual pharmacological agents.

Recruitment of non-perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

KEY POINTS

A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries. In the present study, we report that high altitude-induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance. Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude-related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis. The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success.

ABSTRACT

A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVD_NG ). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm^-2 (P < 0.01). The difference between TVD and TVD_NG was 2.28 ± 4.59 mm mm^-2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVD_NG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVD_NG in non-summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingual capillary TVD to increase microcirculatory oxygen extraction capacity at HA was found to be an intrinsic mechanism of the microcirculation independent of cardiac output changes. Microvascular reactivity to topical nitroglycerin demonstrated that HA-related capillary recruitment is a functional response as opposed to a structural change. The performance of the vascular microcirculation needed to reach the summit was found to be associated with a higher TVD at SL and the ability to further increase TVD_NG upon ascent to extreme altitude.

Effect of ephedrine on gastric conduit perfusion measured by laser speckle contrast imaging after esophagectomy: a prospective in vivo cohort study

Compromised perfusion due to ligation of arteries and veins in esophagectomy with gastric tube reconstruction often (5-20%) results in necrosis and anastomotic leakage, which relate to high morbidity and mortality (3-4%). Ephedrine is used widely in anesthesia to treat intraoperative hypotension and may improve perfusion by the increase of cardiac output and mean arterial pressure (MAP). This study tests the effect of ephedrine on perfusion of the future anastomotic site of the gastric conduit, measured by laser speckle contrast imaging (LSCI). This prospective, observational, in vivo pilot study includes 26 patients undergoing esophagectomy with gastric tube reconstruction from October 2015 to June 2016 in the Academic Medical Center (Amsterdam). Perfusion of the gastric conduit was measured with LSCI directly after reconstruction and after an increase of MAP by ephedrine 5 mg. Perfusion was quantified in flux (laser speckle perfusion units, LSPU) in four perfusion locations, from good perfusion (base of the gastric tube) toward decreased perfusion (fundus). Intrapatient differences before and after ephedrine in terms flux were statistically tested for significance with a paired t-test. LSCI was feasible to image gastric microcirculation in all patients. Flux (LSPU) was significantly higher in the base of the gastric tube (791 ± 442) compared to the fundus (328 ± 187) (P < 0.001). After administration of ephedrine, flux increased significantly in the fundus (P < 0.05) measured intrapatients. Three patients developed anastomotic leakage. In these patients, the difference between measured flux in the fundus compared to the base of the gastric tube was high. This study presents the effect of ephedrine on perfusion of the gastric tissue measured with LSCI in terms of flux (LSPU) after esophagectomy with gastric tube reconstruction. We show a small but significant difference between flux measured before and after administration of ephedrine in the future anastomotic tissue (313 ± 178 vs. 397 ± 290). We also show a significant decrease of flux toward the fundus.

Calcification of arteries supplying the gastric tube: a new risk factor for anastomotic leakage after esophageal surgery

PURPOSE

To evaluate the association between the amount and location of calcifications of the supplying arteries of the gastric tube, as determined with a vascular calcification scoring system, and the occurrence of anastomotic leakage after esophagectomy with gastric tube reconstruction in patients with esophageal cancer.

MATERIALS AND METHODS

Institutional review board approval was obtained, and the informed consent requirement was waived for this retrospective study. Consecutive patients who underwent elective esophagectomy for cancer with gastric tube reconstruction and cervical anastomosis between 2003 and 2012 were identified from a prospective database. Vascular calcification scores were retrospectively assigned by reviewing the routine preoperative computed tomographic (CT) images. In patients with anastomotic leakage, presence and severity of calcifications of the aorta (score of 0-2), celiac axis (score of 0-2), right postceliac arteries (common hepatic, gastroduodenal, and right gastroepiploic arteries; score of 0-1), and left postceliac arteries (splenic and left gastroepiploic arteries, score of 0-1) along with patient- and procedure-related characteristics were compared with those of patients without leakage by using multivariate logistic regression analysis.

RESULTS

Of 246 patients, 58 (24%) experienced anastomotic leakage. No significant differences in patient-related factors were found between patients with leakage and those without leakage, with the exception of more chronic use of steroids in the leakage group (7% [four of 58] vs 0% [0 of 188], P = .003). At univariate analysis, leakage was more common in patients with calcification of the aorta (27% [28 of 102] and 35% [13 of 37] vs 16% [17 of 107], P = .029) and the right postceliac arteries (55% [six of 11] vs 22% [52 of 235], P = .013). At multivariate analysis, both minor (odds ratio, 2.00; 95% confidence interval: 1.02, 3.94) and major (odds ratio, 2.87; 95% confidence interval: 1.22, 6.72) aortic calcifications were associated with leakage. Also, an independent association with leakage was found for calcifications of the right postceliac arteries (odds ratio, 4.22; 95% confidence interval: 1.24, 14.4).

CONCLUSION

Atherosclerotic calcification of the aorta and right postceliac arteries that supply the gastric tube is an independent risk factor for anastomotic leakage after esophagectomy.

Surgical quality of care in esophageal malignancies

Aim: Esophagectomy is the primary surgical treatment for localized malignant neoplasms of the esophagus, and while outcomes have shown that substantial improvement has been made, the ceiling for improvement is still high. Methods: A total of 2506 publications published from January 2002 to March 2012 were identified from PubMed, MEDLINE and the Cochrane Library using the keywords: ‘esophagectomy’, ‘esophagus’, ‘neoplasm’ and ‘cancer’ to identify quality key surgical articles in esophagectomy that were broken down into three groups: preoperative, intraoperative and postoperative care. Discussion: There have been limited preoperative surgical trials, mostly in preoperative antibiotic use, which have led to changes in surgical management. Key and substantial changes have occurred in the intraoperative management for esophageal malignancies around surgical anastomosis technique and anesthesia. Nutritional outcomes still remain a key challenge, and currently there is no established standard of care in the postoperative management of esophagectomy patients. Conclusion: We established quality parameters for leak rates, overall morbidity and mortality, and these form the foundation from which all esophageal surgeons should rank their results. We then utilized the techniques described above to maintain those rates or, better yet, to significantly improve those rates in each surgeons’ practice.

Anesthetic management for esophageal resection

Surgical resection remains a standard treatment option for localized esophageal cancer. Surgical approaches to esophagectomy include transhiatal and transthoracic techniques as well as minimally invasive techniques that have been developed to reduce the morbidities associated with laparotomy and thoracotomy incisions. The perioperative mortality for esophagectomy remains high with cardiopulmonary and anastomotic complications as the most frequent and serious morbidities. This article reviews the management of patients presenting for esophagectomy, with a focus on evidence-based anesthetic and perioperative approaches for improving outcomes.

Application of the HyperEye Medical System for esophageal cancer surgery: a preliminary report

The HyperEye Medical System is a newly developed device that allows for the visualization of the fluorescent image of indocyanine green enhanced by near-infrared light among the surrounding vivid color images. We recently applied this system to confirm the blood flow of an esophageal substitute, and for sentinel node navigation during esophagectomy. Five consecutive patients with thoracic esophageal cancer who underwent a subtotal esophagectomy between June 2010 and May 2011 were enrolled in the study. The esophageal substitute used for reconstruction was the stomach and ileocecum in four and one cases, respectively. In all cases with a reconstructive stomach, fine arterial blood flow and venous perfusion were observed. The blood flow of the reconstructive colon was poor before microvascular anastomosis, however, it dramatically increased after anastomosis. Concerning the sentinel node navigation, the fluorescence of lymph nodes, lymphatic vessels, and the tumor site were detected. The postoperative courses of all cases were uneventful, with no mortalities or anastomotic leakage occurring.

The role of vasoactive agents in the resuscitation of microvascular perfusion and tissue oxygenation in critically ill patients

Purpose

The clinical use of vasoactive drugs is not only intended to improve systemic hemodynamic variables, but ultimately to attenuate derangements in organ perfusion and oxygenation during shock. This review aims (1) to discuss basic physiology with respect to manipulating vascular tone and its effect on the microcirculation, and (2) to provide an overview of available clinical data on the relation between vasoactive drugs and organ perfusion, with specific attention paid to recent developments that have enabled direct in vivo observation of the microcirculation and concepts that have originated from it.

Methods

A MedLine search was conducted for clinical articles in the English language over the last 15 years pertainig to shock, sepsis, organ failure, or critically ill patients in combination with vasoactive drugs and specific variables of organ perfusion/oxygenation (e.g., tonometry, indocyanine clearance, laser Doppler, and sidestream dark field imaging).

Results

Eighty original papers evaluating the specific relationship between organ perfusion/oxygenation and the use of vasoactive drugs were identified and are discussed in light of physiological theory of vasomotor tone.

Conclusions

Solid clinical data in support of the idea that increasing blood pressure in shock improves microcirculatory perfusion/oxygenation seem to be lacking, and such a concept might not be in line with physiological theory of microcirculation as a low-pressure vascular compartment. In septic shock no beneficial effect on microcirculatory perfusion above a mean arterial pressure of 65 mmHg has been reported, but a wide range in inter-individual effect seems to exist. Whether improvement of microcirculatory perfusion is associated with better patient outcome remains to be elucidated.

Ivor-Lewis esophagectomy with and without laparoscopic conditioning of the gastric conduit

BACKGROUND

Anastomotic leakage is still the major surgical complication following transthoracic esophagectomy with intrathoracic esophagogastrostomy (Ivor-Lewis procedure). Modifications of this standard procedure aim to reduce postoperative morbidity and mortality.

METHODS

In this retrospective analysis of a 12-year period, 419 patients who had an Ivor-Lewis (IL) procedure for esophageal carcinoma were included. Due to modifications of the standard procedure, two different groups were compared with respect to their mortality and anastomotic leakage rate. In 181 patients (43.1%), esophagectomy and gastric reconstruction was performed as a one-stage procedure (classical IL group). Two hundred thirty-eight patients (56.9%) underwent a modified IL procedure that included minimally invasive gastric mobilization and a two-stage operation following ischemic conditioning of the gastric conduit.

RESULTS

The hospital mortality rate was lower in the modified IL group without statistical significance (2.9 vs. 6.1%). Thirty-five anastomotic leaks were diagnosed postoperatively, 17 in the classical IL group (9.4%) and 18 in the modified IL group (7.6%). The rate of late leakages (after the 10th postoperative day) was higher in the modified IL group. Septic complications and mortality following anastomotic leakage were less frequent in the modified IL group. Leaks in the classical IL group predominantly required rethoracotomy, whereas leaks of the modified IL group were sufficiently treated with endoscopic stenting.

CONCLUSIONS

Surgical modifications of the classical IL procedure, including a minimally invasive approach and ischemic conditioning of the gastric conduit, seem to reduce postoperative morbidity and mortality. However, due to the retrospective design of this study, the impact of other factors influencing the outcome cannot be ruled out.

Preoperative risk assessment and prevention of complications in patients with esophageal cancer

In this review the preoperative risk assessment and prevention of complications in patients undergoing esophagectomy for cancer is discussed. Age, pulmonary and cardiovascular condition, nutritional status, and neoadjuvant chemo(radio)therapy are known predictive factors. None of these factors is a valid exclusion criterion for esophagectomy, but may help in careful patient selection. Both anesthetists and surgeons play an important role in intraoperative risk reduction by means of appropriate fluid management and application of optimal surgical techniques.

Microvascular flow and tissue oxygenation after major abdominal surgery: association with post-operative complications

OBJECTIVE

To evaluate the relationship between global oxygen delivery (DO(2)I), microvascular flow and tissue oxygenation in patients who did and did not develop complications following major abdominal surgery.

DESIGN

Prospective observational study.

SETTING

Post-operative critical care unit.

PARTICIPANTS

Twenty-five patients receiving standard peri-operative care following major abdominal surgery.

MEASUREMENTS AND MAIN RESULTS

Data were collected before, and for 8 h after surgery. DO(2)I was measured by lithium dilution and arterial waveform analysis. Cutaneous PtO(2) was measured at two sites on the abdominal wall using a Clark electrode. The sublingual microcirculation was visualised using sidestream darkfield imaging. Cutaneous red cell flux was measured using laser Doppler flowmetry. Fourteen patients (56%) developed complications with two deaths. Small vessel (<20 microm) microvascular flow index in those patients who developed complications was lower before (P < 0.05) and after surgery (P < 0.0001) compared to patients who did not develop complications. Both the proportion and density of perfused small vessels were also lower in patients who developed complications after surgery (P < 0.01) but not before surgery. DO(2)I was low in all patients but did not differ between patients who did and did not develop complications. Similarly, there were no associated differences in cutaneous red cell flux or PtO(2).

CONCLUSION

In a group of patients with low DO(2)I following major abdominal surgery, microvascular flow abnormalities were more frequent in patients who developed complications. However, there were no differences in DO(2)I, cutaneous PtO(2) or red cell flux between the two groups. Impaired microvascular flow may be associated with the development of post-operative complications.

Quantitative measurement of gastric mucosal microcirculation using a combined laser Doppler flowmeter and spectrophotometer

Anastomotic leakage after esophagectomy and esophagogastrostomy depends on the vascularization of the gastric conduit. So far, no adequate methods are available to monitor postoperatively mucosal microcirculation of the gastric conduit. The aim of this experimental study was to assess a recently developed microprobe with a microlight-guide spectrophotometer (O2C, Fa. LEA Medizintechnik, Giessen, Germany) to quantitatively measure gastric mucosal blood flow (MBF) and mucosal oxygen saturation (MOS) of different gastric areas. Eighteen patients without gastric pathology were included in this study. During conventional gastroscopy the microprobe was introduced via the working channel of a standard endoscope and positioned in well-defined areas of the antrum and fundus. The tip of the microprobe consisted of a combined laser Doppler and tissue spectrometer measuring continuously the MBF (perfusion units, PU) and MOS (SO(2), in %). The mean MOS of the antrum was significantly higher compared with the fundus (antrum: 82% +/- 7.9 standard deviation [SD], fundus: 72% +/- 10.4; P = 0.0002). The mean MBF was not significantly different between antrum and fundus (antrum: 201 PU +/- 40 SD, fundus: 223 PU +/- 29 SD). This study demonstrates the feasibility of the gastric O2C microprobe to measure parameters of gastric microcirculation from the endoluminal side.

Year in review 2006: Critical Care--Cardiology

This review summarizes key research papers published in the fields of cardiology and intensive care during 2006 in Critical Care and, where relevant, in other journals within the field. The papers have been grouped into categories: haemodynamic monitoring, vascular access in intensive care, microvascular assessment and manipulation, and impact of metabolic acidosis on outcome.