Emergency tracheal intubation in 202 patients with COVID-19 in Wuhan, China: lessons learnt and international expert recommendations

Tracheal intubation in coronavirus disease 2019 (COVID-19) patients creates a risk to physiologically compromised patients and to attending healthcare providers. Clinical information on airway management and expert recommendations in these patients are urgently needed. By analysing a two-centre retrospective observational case series from Wuhan, China, a panel of international airway management experts discussed the results and formulated consensus recommendations for the management of tracheal intubation in COVID-19 patients. Of 202 COVID-19 patients undergoing emergency tracheal intubation, most were males (n=136; 67.3%) and aged 65 yr or more (n=128; 63.4%). Most patients (n=152; 75.2%) were hypoxaemic (Sao₂ <90%) before intubation. Personal protective equipment was worn by all intubating healthcare workers. Rapid sequence induction (RSI) or modified RSI was used with an intubation success rate of 89.1% on the first attempt and 100% overall. Hypoxaemia (Sao₂ <90%) was common during intubation (n=148; 73.3%). Hypotension (arterial pressure <90/60 mm Hg) occurred in 36 (17.8%) patients during and 45 (22.3%) after intubation with cardiac arrest in four (2.0%). Pneumothorax occurred in 12 (5.9%) patients and death within 24 h in 21 (10.4%). Up to 14 days post-procedure, there was no evidence of cross infection in the anaesthesiologists who intubated the COVID-19 patients. Based on clinical information and expert recommendation, we propose detailed planning, strategy, and methods for tracheal intubation in COVID-19 patients.

Emergency tracheal intubation in 202 patients with COVID-19 in Wuhan, China: lessons learnt and international expert recommendations

Tracheal intubation in coronavirus disease 2019 (COVID-19) patients creates a risk to physiologically compromised patients and to attending healthcare providers. Clinical information on airway management and expert recommendations in these patients are urgently needed. By analysing a two-centre retrospective observational case series from Wuhan, China, a panel of international airway management experts discussed the results and formulated consensus recommendations for the management of tracheal intubation in COVID-19 patients. Of 202 COVID-19 patients undergoing emergency tracheal intubation, most were males (n=136; 67.3%) and aged 65 yr or more (n=128; 63.4%). Most patients (n=152; 75.2%) were hypoxaemic (Sao₂ <90%) before intubation. Personal protective equipment was worn by all intubating healthcare workers. Rapid sequence induction (RSI) or modified RSI was used with an intubation success rate of 89.1% on the first attempt and 100% overall. Hypoxaemia (Sao₂ <90%) was common during intubation (n=148; 73.3%). Hypotension (arterial pressure <90/60 mm Hg) occurred in 36 (17.8%) patients during and 45 (22.3%) after intubation with cardiac arrest in four (2.0%). Pneumothorax occurred in 12 (5.9%) patients and death within 24 h in 21 (10.4%). Up to 14 days post-procedure, there was no evidence of cross infection in the anaesthesiologists who intubated the COVID-19 patients. Based on clinical information and expert recommendation, we propose detailed planning, strategy, and methods for tracheal intubation in COVID-19 patients.

Current cancer therapies - a guide for perioperative physicians

Cancer is expected to be the leading cause of death around the world. New cancer therapies have improved survival but they can also lead to complications and toxicity. In this article, the effects of modern anti-cancer therapies are reviewed. The perioperative effects of chemotherapy, radiotherapy and experimental therapies in relation to anaesthesia are discussed. Common and rare complications are summarised as is advice for optimal treatment of the cancer patient in the perioperative period.

Can sugammadex save a patient in a simulated 'cannot intubate, cannot ventilate' situation?

Recent studies have shown that the use of high dose rocuronium followed by sugammadex provides a faster time to recovery from neuromuscular blockade following rapid sequence induction than suxamethonium. In a manikin-based 'cannot intubate, cannot ventilate' simulation, we studied the total time taken for anaesthetic teams to prepare and administer sugammadex from the time of their initial decision to use the drug. The mean (SD) total time to administration of sugammadex was 6.7 (1.5) min, following which a further 2.2 min (giving a total 8.9 min) should be allowed to achieve a train-of-four ratio of 0.9. Four (22%) teams gave the correct dose, 10 (56%) teams gave a dose that was lower than recommended, four (22%) teams gave a dose that was higher than recommended, six (33%) teams administered sugammadex in a single dose, and 12 (67%) teams gave multiple doses. Our simulation highlights that sugammadex might not have saved this patient in a 'cannot intubate, cannot ventilate' situation, and that difficulties and delays were encountered when identifying, preparing and administering the correct drug dose.

[Awake fibrecapnic intubation]

Awake flexible intubation is the gold standard for difficult airway management but failures have been reported in up to 13% of cases. A novel technique called 'awake fibrecapnic intubation', developed in the Netherlands, is described here for the intubation of patients with head and neck cancer who have a difficult airway. After topical anaesthesia is administered, a flexible fibrescope is introduced into the pharynx. A special suction catheter is then advanced through the suction channel of this scope and then into the airway for the recording of carbon dioxide measurements. The catheter may also be used for oxygenation during the procedure. Spontaneous respiration is maintained in all patients. When four capnograms have been obtained, the flexible scope is railroaded over the catheter and after identification of tracheal rings or carina, the tracheal tube is placed. This new intubation technique is easier to learn than awake flexible intubation.

Volatile anesthetics modulate gene expression in breast and brain tumor cells

Gene expression is increasingly used for diagnostic, prognostic, and therapeutic purposes in clinical practice. We tested the hypothesis that volatile anesthetics (VA) affect gene expression of tumor cells. Cells from the neuronal cell line SH-SY5Y and from the breast cell line MCF-7 were exposed ex vivo to enflurane, isoflurane, desflurane, halothane, sevoflurane, or nitrous oxide. Microarray gene expression profiles were studied. We observed significant differences in gene expression levels of cell cultures and response in time when exposed to different VA. Some genes used for predictive genetic fingerprints for breast cancer were affected by VA. Our findings suggest that VA modulate gene expression in breast and brain tumor cell cultures in a unique and time-dependent manner.

Awake fibrecapnic intubation in head and neck cancer patients with difficult airways: new findings and refinements to the technique

Recently, we described an adaptation of awake fibreoptic intubation that we call awake fibrecapnic intubation. The aim of this study was to evaluate the efficacy and risk of complications with this novel technique in a consecutive case series of head and neck cancer patients known to have difficult airways. We prospectively studied 40 consecutive intubations in head and neck cancer patients prior to a diagnostic or surgical procedure. Following topical anaesthesia, a flexible bronchoscope was introduced into the pharynx; spontaneous respiration was maintained in all patients. A special suction catheter was advanced into the airway through the suction channel of the bronchoscope for carbon dioxide measurements. When four capnograms were obtained, the bronchoscope was railroaded over the catheter and a tracheal tube was placed. All adverse events and complications were recorded. There were no complications associated with the technique. The median (range) time to intubation was 3 min (1.5-15 min). All patients were intubated successfully, 39 (98%) of them using awake fibrecapnic intubation. There was one patient with severe tumour bleeding and acute airway obstruction caused by advancement of the tube over the bronchoscope. This was not considered to be a complication of the fibrecapnic technique. Awake fibrecapnic intubation is a safe and valuable technique in head and neck cancer patients with a difficult airway.

Awake fibrecapnic intubation: a novel technique for intubation in head and neck cancer patients with a difficult airway

Awake fibreoptic intubation is the gold standard for difficult airway management but failures are reported in the literature in up to 13% of cases. In case of failure, a tracheotomy is often indicated. We describe a novel technique for intubation in head and neck cancer patients with a difficult airway that we call awake fibrecapnic intubation. The aim of this study was to investigate the feasibility of this technique. We studied prospectively 15 consecutive intubations in head and neck cancer patients before diagnostic or therapeutic surgical procedures. After topical anaesthesia, a fibrescope was introduced into the pharynx. Spontaneous respiration was maintained in all patients. Through the suction channel of the fibrescope a special suction catheter was advanced into the airway for carbon dioxide measurements. When four capnograms were obtained, the fibrescope was railroaded over the catheter and after identification of tracheal rings, a tracheal tube was placed. Tracheal intubation was successful in all patients without bleeding or complications, with a median (range) time to intubation of 3 (2-15) min. Identification of the vocal cords and glottis was difficult in four patients due to extensive anatomical abnormalities or poor visibility; even in these patients, a capnogram was obtained within 4 s.

Cardiovascular and respiratory complications after major head and neck surgery

BACKGROUND

Our aim was to gain insight into the incidence rates for, distribution of, and risk factors of postoperative cardiovascular and respiratory complications in major head and neck surgery.

METHODS

We performed a retrospective review of 469 patients who had undergone primary major head and neck surgery. Outcome measures were incidence rates, risk factors, and distribution over time for postoperative cardiovascular and respiratory complications. A multivariate analysis was performed.

RESULTS

The incidence rates for cardiovascular and respiratory complications were 57 of 469 (12%) and 50 of 469 (11%), respectively. The incidence rate for heart failure exceeded that for pneumonia. The peak incidence for cardiovascular complications was on the first postoperative day; for respiratory complications, on the second postoperative day. Risk factors for cardiovascular complications were age, pulmonary disease, alcohol abuse, and tumor location; risk factors for respiratory complications were pulmonary disease, previous myocardial infarction, and American Society of Anesthesiologists (ASA) grade.

CONCLUSION

In this study, the incidence rates for cardiovascular and respiratory complications were very similar. The first postoperative day was crucial with regard to cardiovascular complications. Age and chronic pulmonary diseases were the common risk factors for cardiovascular and respiratory complications.

Predictive value of planar 18F-fluorodeoxyglucose imaging for cardiac events in patients after acute myocardial infarction

This long-term study examines the predictive value of planar myocardial 18F-fluorodeoxyglucose (FDG) imaging for cardiac events after acute myocardial infarction (AMI). From December 1989 to April 1991, 59 consecutive patients with AMI had undergone planar rest thallium-201 (Tl-201)/FDG imaging for viability assessment; 53 (42 men) were included in this study. Mean follow-up was 47 +/- 15 months. Cardiac events were defined as cardiac-related death, reinfarction, late revascularization, and unstable angina pectoris. A mismatch pattern was defined as a FDG uptake exceeding Tl-201 uptake by > or = 20%. A concordant reduction in flow and metabolism was defined as a match. In the mismatch group (n = 39) were 19 events versus 1 event in the match group (n = 14) (p <0.009). In the mismatch group were 5 cardiac deaths, 3 reinfarctions, 7 late revascularizations, and 4 patients had unstable angina pectoris. There was 1 cardiac death in the match group. The event-free rate estimated using Kaplan Meier curves for patients with and without a mismatch was significantly different (p = 0.018). The relative risk for patients with a mismatch for developing a future cardiac event was estimated at 7.8 versus patients with a match. Thus, planar myocardial FDG imaging shortly after AMI has important prognostic significance for prediction of future cardiac events. Patients with a mismatch shortly after AMI have a high risk for future cardiac events on medical therapy.

Prediction of improvement of contractile function in patients with ischemic ventricular dysfunction after revascularization by fluorine-18 fluorodeoxyglucose single-photon emission computed tomography

OBJECTIVES

We evaluated the use of fluorine-18 fluorodeoxyglucose (FDG) and single-photon emission computed tomography (SPECT) to predict improvement of left ventricular ejection fraction (LVEF) after revascularization.

BACKGROUND

FDG SPECT has recently been proposed for assessment of myocardial viability. However, FDG SPECT still awaits validation in terms of predicting improvement of contractile function after revascularization in patients with poor left ventricular (LV) function.

METHODS

Fifty-five patients with contractile dysfunction (including 22 with LVEF < 30%) underwent FDG SPECT during hyperinsulinemic glucose clamping and early thallium-201 SPECT (to assess perfusion). Improvement of LV function was evaluated 3 months after revascularization with echocardiography and radionuclide ventriculography.

RESULTS

The 55 patients were arbitrarily classified into two groups: 19 with three or more viable, dysfunctional segments on FDG SPECT and 36 with less than three viable, dysfunctional segments. LVEF increased significantly in the first group, from 28 +/- 8% (mean +/- SD) before to 35 +/- 9% (p < 0.01) after revascularization. In the second group, LVEF remained unchanged after revascularization (45 +/- 14% vs. 44 +/- 14%, p = NS). The 22 patients with severely depressed LV function were similarly classified into two groups: 14 with three or more viable segments on FDG SPECT in whom LVEF improved significantly (25 +/- 6% vs. 32 +/- 6%) and 8 with less than three viable segments in whom LVEF remained unchanged (24 +/- 6% vs. 25 +/- 6%).

CONCLUSIONS

This study shows that FDG SPECT can identify patients in whom LV function improves after revascularization. Because SPECT is widely available, this technique may contribute to more routine use of FDG for determination of viability.

F18-fluorodeoxyglucose single-photon emission computed tomography predicts functional outcome of dyssynergic myocardium after surgical revascularization

BACKGROUND

Prediction of functional recovery after revascularization is possible with positron emission tomography and F18-fluorodeoxyglucose (FDG). Recently, the use of FDG in combination with single-photon emission computed tomography (SPECT), with 511 keV collimators, has been proposed to allow more widespread use of FDG. In the current study we aimed to predict improvement of regional left ventricular function after surgical revascularization with FDG and SPECT.

METHODS AND RESULTS

Twenty-seven patients with regional wall motion abnormalities (on echocardiography) underwent early thallium-201 (Tl-201) SPECT to assess perfusion and FDG SPECT to assess regional glucose uptake. The left ventricular myocardium was divided into 13 segments. For each segment, tracer uptake was evaluated visually (with the use of a 4-point scoring system) by consensus of two observers. Myocardial viability was determined in dyssynergic segments on echocardiography and defined as normal perfusion or increased FDG uptake in a perfusion defect (mismatch). Absence of viability was defined as a perfusion defect without increased FDG uptake (match). Improvement of regional wall motion was assessed 3 months after revascularization. In the group of segments that were viable on FDG/Tl-201 SPECT (n = 64), the segmental wall motion score decreased from 1.4 +/- 0.5 to 0.6 +/- 0.7 (p < 0.01), whereas the segmental wall motion score remained unchanged in nonviable segments (n = 72): 1.6 +/- 0.5 versus 1.5 +/- 0.6 (not significant). Forty-six (72%) of the 64 segments that were viable on FDG/Tl-201 SPECT demonstrated improved contractile function after coronary revascularization. In contrast, only 7 (10%) of 72 nonviable segments on FDG/Tl-201 SPECT showed improvement in function after revascularization (p < 0.01 versus viable segments). The sensitivity, specificity, and positive and negative predictive values were 87%, 78%, 72%, and 90%, respectively.

CONCLUSION

This study shows that FDG/Tl-201 SPECT can identify patients who improve in regional ventricular function after revascularization.

Cardiac 18F-FDG-SPET studies in patients with non-insulin-dependent diabetes mellitus during hyperinsulinaemic euglycaemic clamping

Identification of viable myocardium is possible with 18F-fluorodeoxyglucose (FDG) and positron emission tomography (PET). More recently, the feasibility of cardiac FDG imaging with single photon emission tomography (SPET) has been reported. In patients with diabetes mellitus, poor image quality is frequently obtained with FDG-PET, due to relative or absolute insulin deficiency and peripheral insulin resistance. To improve image quality of the FDG-PET studies, the hyperinsulinaemic glucose clamp has been proposed. We assessed the image quality of cardiac FDG-SPET studies in 10 patients with non-insulin-dependent diabetes mellitus (NIDDM) and compared the results with those obtained in 10 patients without NIDDM. All FDG studies were performed during hyperinsulinaemic glucose clamping. Image quality was expressed as myocardial to blood pool activity (M/B) ratios. Residual viability was assessed in dysfunctional myocardium. The M/B ratios were comparable between patients with and without NIDDM (2.67 +/- 0.8 vs 2.50 +/- 0.7, N.S.). Residual viability was detected in 51% of the dysfunctional segments of the patients with NIDDM and in 49% of the segments of the patients without NIDDM. In the small subset of patients (n = 10) undergoing revascularization, 19 of 20 (95%) segments that had improved wall motion were viable on FDG-SPET. In contrast, 27 of 36 (75%) segments that did not improve were necrotic on FDG-SPET. Thus FDG-SPET during hyperinsulinaemic glucose clamping provides adequate image quality in patients with NIDDM compared with patients without NIDDM, and can be used in the detection of viable myocardium.

Course of impaired left ventricular function after acute myocardial infarction predicted with planar thallium-201 chloride and F18-fluorodeoxyglucose imaging

Planar reset myocardial thallium-201 chloride (201Tl)/F18-fluorodeoxyglucose (FDG) imaging has been shown to distinguish between viable and non-viable tissue. Twenty-five patients (60 +/- 9 years) with acute myocardial infarction were studied using this technique within 6 +/- 2 days (T1) after infarction and again after 42 +/- 4 days (T6). Serial assessment of wall motion with 2D-echocardiography was performed to determine the predictive value of radionuclide indices for the course of impaired regional left ventricular function. No revascularization procedure was performed. Segmental 201Tl and FDG uptake was evaluated using circumferential profiles. Echocardiographic wall motion was scored as normal, hypokinetic or akinetic. Myocardial segments were considered non-viable if a match between 201Tl and FDG uptake was present, which is a concordant reduction in 201 Tl and FDG uptake (Group A). Myocardial segments were considered viable if: a mismatch was present between 201Tl and FDG uptake which was defined as a segmental FDG uptake exceeding 201Tl uptake by > or = 20% in a segment with reduced 201Tl uptake (Group B); a normal FDG uptake (> or = 75%) was present without a mismatch pattern in a segment with reduced 201Tl uptake (201Tl < 75% of peak activity) (Group C); a normal 201Tl uptake was present in the area of wall motion abnormality (Group D). Corresponding scintigraphic images obtained at T1 and T6 were compared.

RESULTS

51 segments were normokinetic, 37 were hypokinetic and 6 were akinetic at T1. Of the 63 segments with wall motion abnormalities at T1, 18 regions showed a match (FDG-201Tl < 20%) (Group A). Regional function improved in only one (6%) of these segments. In 19 regions a mismatch was present (FDG-201Tl > 20%) (Group B) of which three (16%) showed spontaneous improvement in function (p = NS vs. matched segments), although recovery varied considerably among patients. Regional function in two segments deteriorated. In 14 regions with reduced 201Tl uptake, FDG uptake was normal (Group C) of which five (36%) were improved after 6 weeks (p < 0.05 vs. match; p = NS vs. mismatched segments). Of the 12 segments with normal 201Tl uptake (Group D), seven (58%) showed improvement in function, whereas five (42%) did not show improvement (p < 0.05 vs. match). In addition, all scintigraphically selected viable segments were grouped (Group B + C + D) and compared with the non-viable segments (Group A). The predictive value of a positive viability test for spontaneous functional improvement was 33%. The predictive value of a negative viability test for lack of functional improvement was 94%.

CONCLUSIONS

absence of residual FDG uptake shortly after infarction is associated with irreversible injury, while preservation of metabolic activity identifies segments with variable outcome. Wall motion alone is not a good indicator for the presence of viable tissue. Planar 201Tl/FDG imaging allows early identification of viable but jeopardized tissue and may help select patients who will benefit from aggressive therapy to salvage endangered myocardium.

Detection of viability after myocardial infarction: available techniques and clinical relevance--a review

The differentiation of viable from nonviable myocardium in patients with myocardial infarction (MI) and left ventricular (LV) dysfunction is of important clinical relevance. It is now known that impaired LV function after infarction not always represents an irreversible process. LV ejection fraction is significantly reduced in many patients after infarction and, although abnormally contracting myocardial segments may result from irreversible scarring, numerous studies have shown that many asynergic zones have sustained metabolic activity. An accurate detection of myocardial viability aids in clinical decision making to select the appropriate therapy for patients with MI. Recently, cardiac imaging techniques that evaluate myocardial viability on the basis of myocardial perfusion, cell membrane integrity, metabolic activity and residual coronary reserve, have been developed with clinical success. These methods provide greater precision in the assessment of viable myocardium than can be achieved by analysis or coronary anatomy, regional function or the presence or absence of electrocardiographic Q waves, criteria that were used in the past. The clinical challenge is to predict which myocardial regions are viable and will improve systolic function after revascularization, thereby enhancing global LV function. In this review, the currently available imaging techniques for assessment of myocardial viability are discussed.

Influence of high and low plasma insulin levels on the uptake of fluorine-18 fluorodeoxyglucose in myocardium and femoral muscle, assessed by planar imaging

The aim of this study was to optimize the metabolic conditions for planar myocardial fluorine-18 fluorodeoxyglucose (FDG) imaging. The effects of high and low insulin levels during euglycaemic clamping on myocardial and femoral muscle FDG uptake were compared since insulin plays a major role in glucose metabolism. FDG uptake in 11 patients was studied using planar scintigraphy. Patients were studied twice: in the low-dose insulin protocol (LDI), insulin was infused at a rate of 20 mU/kg per hour, starting 1 h before FDG administration, while in the high-dose insulin protocol (HDI) it was infused at a rate of 100 mU/kg per hour. Glucose infusion rate was adjusted according to frequently determined blood glucose levels. Somatostatin was infused to block endogenous insulin release. Planar images were obtained from the thorax region and femoral muscles. Regions of interest were drawn over normal and abnormal myocardial areas (based on angiographic and thallium-201 data) and over lung, liver and muscle areas. After clamping, insulin levels during LDI and HDI at t = 60 were 30.6 +/- 13.3 and 129.6 +/- 30.5 mU/l respectively (P < 0.0001). Femoral muscle uptake was significantly higher during HDI (P < 0.001). Uptake in normal and abnormal myocardial areas did not differ between the two protocols. Heart/lung ratios (NS) and heart/liver ratios (P < 0.05) increased during HDI. It may be concluded that planar FDG imaging is influenced by plasma insulin levels. The euglycaemic hyperinsulinaemic clamp technique, although more demanding, gives an adjustable metabolic steady state without significantly altering the FDG uptake patterns in normal and abnormal myocardial regions. The image quality of planar FDG images improves due to lower background uptake of FDG during clamping with high plasma insulin levels.

Feasibility of planar fluorine-18-FDG imaging after recent myocardial infarction to assess myocardial viability

The aim of this study was to define the clinical feasibility of planar myocardial 18F-fluorodeoxyglucose (FDG) imaging and to assess the relation between 201Tl, FDG and left ventricular function early after myocardial infarction.

METHODS

Fifty-one patients were studied 5 +/- 2 days after infarction. Scintigraphic images were visually and quantitatively analyzed using a circumferential profiles technique. FDG uptake was normalized to the area with maximal 201Tl uptake. Scintigraphic data were compared with left ventricular wall motion as assessed by ventriculography in 22 patients. Relative regional 201Tl uptake was categorized as normal (> or = 75% of peak activity), moderately reduced (50%-75%) or severely reduced (< 50%). These tracer defects were considered viable if FDG uptake exceeded 201Tl uptake by > or = 20% and/or if FDG uptake was normal (> or = 75%). All regions with FDG uptake 20% less than 201Tl uptake were considered nonviable.

RESULTS

Four hundred forty-one myocardial regions were analyzed; 200 showed normal 201Tl uptake, 241 had reduced uptake, 191 had moderately reduced 201Tl uptake and 50 regions had severely reduced uptake. Viability for moderately and severely reduced regions was observed in 62% and 48%, respectively. A concordance between flow and metabolism was observed in 38% and 52%, respectively.

CONCLUSION

Myocardial FDG imaging is feasible with standard gamma camera systems and enables the identification of regions with preserved glucose metabolism in patients shortly after infarction.

Relation between myocardial uptake of thallium-201 chloride and fluorine-18 fluorodeoxyglucose imaged with single-photon emission tomography in normal individuals

Recently, we have demonstrated the feasibility of imaging myocardial uptake of fluorine-18 fluorodeoxyglucose (FDG) with single-photon emission tomography (SPET) using a specially designed collimator. Thallium-201 was used to determine distribution of perfusion for comparison with FDG uptake. However, regional 201Tl and FDG activities may be different, based on differences in tracer attenuation and the use of different collimators. To study the relation between tracer activities imaged with SPET, nine healthy individuals underwent resting 201Tl SPET and FDG SPET during a hyperinsulinaemic euglycaemic clamp. The SPET data were analysed semiquantitatively, using circumferential profiles. Mean profiles of midventricular short-axis slices showed no significant difference between 201Tl and FDG activity. Regional fluctuations were similar for FDG and 201Tl; the highest tracer activities were observed in the lateral wall and the lowest activities in the septum. Finally, pooled data (n = 1620 segmental activities) in nine individuals showed a linear correlation (P < 0.0001) between 201Tl and FDG activity: FDG = 0.76 201Tl + 0.23 (r = 0.70). These data demonstrate the absence of major differences between regional 201Tl and FDG activity in normal myocardium, suggesting that no separate 201Tl and FDG SPET reference values are needed for comparison with patient studies.

Feasibility of assessing regional myocardial uptake of 18F-fluorodeoxyglucose using single photon emission computed tomography

Differentiation between viable myocardium and scar tissue in segments with abnormal contraction has important consequences in the clinical management of patients with coronary artery disease. Positron emission tomography (PET) can identify viable tissue using 18F-fluorodeoxyglucose (FDG). However, application of PET for daily routine is limited. In this study, FDG uptake was visualized with single photon emission computed tomography (SPECT) and compared with regional perfusion assessed with thallium-201 (201Tl) SPECT. The scintigraphic findings were related to regional wall motion determined with two-dimensional echocardiography. Patients (n = 9) with wall motion abnormalities underwent FDG SPECT and resting 201Tl SPECT. To control the metabolic status patients were studied with a hyperinsulinaemic euglycemic clamp during FDG SPECT. Analysis of reconstructed data was performed visually and semiquantitatively using circumferential profiles. High-quality images were obtained. Eight 201Tl defects showed concordantly decreased FDG uptake (metabolism-perfusion matches) indicating scarred tissue, whereas six regions of hypoperfusion demonstrated a relatively increased FDG uptake (mismatches), suggesting viable myocardium. Semiquantitative analysis confirmed visual findings. Mean 201Tl and FDG activities were not significantly different in matching defects. In mismatches the mean FDG activity was 81 +/- 11% vs 64 +/- 9% mean 201Tl activity (P < 0.0001). In four of six segments with increased FDG uptake, two-dimensional echo revealed hypokinesia. Seven of eight regions with a matching defect in contrast were akinetic. Thus, in the areas with a mismatch contractility was preserved. We conclude that FDG uptake can be visualized with SPECT. Furthermore, our preliminary observations suggest that this approach can identify viable tissue.