Acta Anaesthesiol Scand 2014; ••: ••–•• Printed in Singapore. All rights reserved
© 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd ACTA ANAESTHESIOLOGICA SCANDINAVICA
doi: 10.1111/aas.12343
Routine pre-operative focused ultrasonography by anesthesiologists in patients undergoing urgent surgical procedures M. T. Bøtker1,2, M. L. Vang1, T. Grøfte1, E. Sloth3 and C. A. Frederiksen4
1 Department of Anesthesiology and Intensive Care, Regional Hospital of Randers, Randers, Denmark, 2Research Center for Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark, 3Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Aarhus, Denmark and 4Department of Internal Medicine, Regional Hospital of Randers, Randers, Denmark
Background: Unexpected cardiopulmonary complications are well described during surgery and anesthesia. Pre-operative evaluation by focused cardiopulmonary ultrasonography may prevent such mishaps. The aim of this study was to determine the frequency of unexpected cardiopulmonary pathology with focused ultrasonography in patients undergoing urgent surgical procedures. Methods: We performed pre-operative focused cardiopulmonary ultrasonography in patients aged 18 years or above undergoing urgent surgical procedures at pre-defined study days. Known and unexpected cardiopulmonary pathology was recorded, and subsequent changes in the anesthesia technique or supportive actions were registered. Results: A total of 112 patients scheduled for urgent surgical procedures were included. Their mean age (standard deviation) was 62 (21) years. Of these patients, 24% were American Society of Anesthesiologists (ASA) class 1, 39% were ASA class 2, 32% were ASA class 3, and 4% were ASA class 4. Unexpected car-
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ardiopulmonary complications are well described during general and regional anesthesia, and emergency surgery and cardiac disease are independent predictors of mortality.1–4 In order to exclude all cardiac and pulmonary pathology, pre-operative examination may have to be expanded to include pulmonary function testing, coronary arteriography, full echocardiography, and computed tomography of the thorax. This, however, is neither necessary nor feasible, and guidelines suggest that pre-operative testing should be conducted only on indication.1,5 Pre-operative expert echocardiography discloses significant pathology in patients with suspected heart disease undergoing noncardiac surgery, and this often leads to changes in perioperative management.6,7 This is especially the case in patients undergoing emergency
diopulmonary pathology was disclosed in 27% [95% confidence interval (CI) 19–36] of the patients and led to a change in anesthesia technique or supportive actions in 43% (95% CI 25–63) of these. Unexpected pathology leading to changes in anesthesia technique or supportive actions was only disclosed in a group of patients above the age of 60 years and/or in ASA class ≥ 3. Conclusion: Focused cardiopulmonary ultrasonography disclosed unexpected pathology in patients undergoing urgent surgical procedures and induced changes in the anesthesia technique or supportive actions. Pre-operative focused ultrasonography seems feasible in patients above 60 year and/or with physical limitations but not in young, healthy individuals. Accepted for publication 27 April 2014 © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
noncardiac surgery.7 These findings are all in accordance with current guidelines, but the use of focused ultrasonography is increasing – especially in anesthesiology and critical care. There is little evidence to support this development, and it is questionable if all pathology needs to be disclosed before anesthesia. Nevertheless, in patients undergoing emergency surgery, time is limited and focused ultrasonography may add additional knowledge of importance to the anesthesia that would otherwise not be disclosed. In order to identify patients that may benefit from focused ultrasonography, we have to examine an unselected cohort undergoing surgery. Focus Assessed Transthoracic Echocardiography (FATE) is a protocol designed to evaluate the hemodynamic and respiratory function, and to
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detect significant cardiovascular and pulmonary pathology by visualization of the heart and the pleura.8 The protocol is easy to learn, and a FATE examination can be completed in less than 2 min.9,10 We hypothesized that unexpected cardiovascular and pulmonary pathology is frequent in unselected patients undergoing urgent surgical procedures and may be discovered by FATE examination. The objective of this study was to quantify unexpected cardiopulmonary pathology by focused ultrasonography in unselected patients undergoing urgent surgical procedures and to evaluate the impact of unexpected pathology on choice of anesthesia technique or supportive actions.
Methods Setting and study population We conducted this prospective cohort study on 24 pre-defined study days from 10 October 2012 to 17 January 2013 at the Regional Hospital of Randers, Denmark. All patients at least 18 years of age undergoing acute orthopedic or abdominal surgery were included. Patients not able or willing to give informed consent and patients previously included in the study were excluded. Logistic reasons also necessitated exclusion of a number of patients (either patients were brought to the operating room while examination of another patient was ongoing or patients had incomplete examinations because they were taken to the operating room immediately). The Central Denmark Region Committee on Biomedical and Research Ethics reviewed the study, and because of the study design, it was exempt from formal ethical approval. We obtained written informed consent from all study participants.
Education and equipment All 24 anesthesiologists, both residents and consultants, at the Regional Hospital of Randers were systematically trained in the FATE protocol in connection with this study. The educational program comprised an e-learning module, a hands-on course, and 10 supervised real-time examinations. The 10 supervised examinations were carried out on 24 pre-defined study days. It was on these days that eligible patients were included. The anesthesiologists in training were real-time supervised by one of two experienced FATE supervisors (both anesthesiologists) who also interpreted the examinations and did the registration. If additional imaging, like extended FATE views and Doppler evaluation, was needed, the supervisors carried this out. We used
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a Vivid S6 (GE Healthcare, Horten, Norway) system equipped with a M4S phased array transducer (1.5– 4.0 MHz).
Examinations and interpretation Patients underwent pre-operative FATE examination at the bedside. Examinations were interpreted according to dichotomous outcomes and cutoff values. Cutoff values were in accordance with recommendations made by the American Society of Echocardiography and the European Association of Echocardiography.11 We assessed the following outcome criteria: 1. Pericardial effusion ≥ 10 mm present? 2. Left ventricle end diastolic diameter ≥ 6.2 cm, indicating left ventricle dilation? 3. Mid right ventricle end diastolic diameter ≥ 42 mm or tricuspid anular plane systolic excursion ≤ 16 mm, indicating right ventricle dilation or systolic dysfunction? 4. Left ventricle septal or posterior wall thickness ≥ 13 mm? In case hypertrophy was present, we assessed whether left atrium diameter was > 50 mm, indicating diastolic dysfunction. 5. Ejection fraction ≤ 40% by eyeballing, indicating left ventricle systolic dysfunction? 6. Visible aortic valve sclerosis? In case sclerosis was present, supervisors assessed whether maximum jet velocity over the aortic valve by Continuous Wave Doppler was ≥ 3 m/s, indicating aortic stenosis. 7. Other obvious pathological findings, processes or excrescences present? 8. Any pleural effusion present? Pathology was registered as known or unexpected based on whether it was encountered by the preceding routine pre-operative evaluation or not. In case of unexpected pathology, the anesthesiologist who had conducted the routine pre-operative evaluation was informed. No interventions were protocolized or recommended by the study group. If the anesthesiologist handling the patient made a change in the anesthesia technique or initiated supportive actions based on this new information, this was registered. In patients requiring full echocardiography by a cardiologist according to guidelines (i.e. known or suspected valve disease and/or clinical suspicion of heart failure), this was performed in accordance with standard procedures. The findings of the full echocardiography were registered as known findings, but focused ultrasonography was also performed, because a classical echocardiography rarely
Pre-operative focused ultrasonography
includes a pleural scan. Quantification of the amount of pleural effusion was done post hoc based on the findings in a recent study in intensive care patients where the pleural scan is carried out with the patient in the supine position as it is done in the FATE examination.12
Met the inclusion criteria (n = 160)
Excluded (n = 48) • Logistical reasons (n = 35) • Lack of informed consent (n = 8) • Previously included (n = 5)
Statistical analysis The primary endpoint was unexpected cardiopulmonary pathology overall. The secondary endpoints were (1) unexpected cardiopulmonary pathology in subgroups of patients based on age and American Society of Anesthesiologists (ASA) physical status classification and (2) changes in anesthesia technique or supportive actions overall and in subgroups. Inherent to the study design, there was no loss to follow-up. We used Fisher’s exact test to compare the proportion of unexpected pathology in subgroups of patients. We calculated odds ratios using Woolf’s method. We used Wilcoxon rank-sum test to compare length of stays. Primary and secondary endpoints are presented as proportions with 95% confidence intervals (CIs). Based on a previously published study, we considered 10% unexpected pathology to be a clinically relevant proportion.3 Based on the assumption, that only very few patients undergoing urgent surgical procedures suffer from unexpected cardiopulmonary disease, we defined a postulated value of 2%. With a power of 0.90 and a significance level of 0.05, we thus needed to include 93 patients. STATA software (StataCorp LP, College Station, TX, USA) was used for all statistical calculations.
Results On the study days, 160 patients underwent urgent surgical procedures; 48 patients were excluded (Fig. 1). A total of 112 patients were included in the study. Baseline characteristics are shown in Table 1, and indication for surgery is shown in Table 2. Pathology was disclosed in 32% (95% CI 24–42) of patients, and 27% (95% CI 19–36) had unexpected pathology (Table 3). In 12% (95% CI 6–18) of the total cohort, focused ultrasonography led to a change in anesthesia technique or supportive actions (Table 4). This corresponds to a change in anesthesia technique or supportive action among 43% (95% CI 25–63) of patients with unexpected pathology. Examples of unexpected pathology are depicted in Fig. 2. There was a higher proportion of unexpected pathology (P < 0.001) among patients above the age
Included in the study (n = 112)
Fig. 1. Patients undergoing urgent surgical procedures excluded from the study.
Table 1 Baseline characteristics for patients undergoing urgent surgical procedures. Characteristic
Patients (n = 112)
Age, years Male ASA physical status class 1 2 3 4 5 6 Ischemic heart disease Heart failure Atrial fibrillation Peripheral arterial disease Aortic valve stenosis Artificial aortic valve Stroke Chronic obstructive pulmonary disorder Asthma Arterial hypertension Hypercholesterolemia Diabetes mellitus Chronic renal failure
62 ± 21 60 (54%) 27 (24%) 44 (39%) 36 (32%) 5 (5%) 0 (0%) 0 (0%) 10 (9%) 5 (4%) 15 (13%) 8 (7%) 1 (1%) 1 (1%) 3 (3%) 10 (9%) 4 (4%) 51 (46%) 21 (19%) 18 (16%) 6 (5%)
ASA, American Society of Anesthesiologists.
of 60 years and/or in ASA class ≥ 3 than in the remaining study population (Table 5). In this highrisk group, unexpected pathology occurred in 39% (95% CI 28–52) of patients. Odds ratio for unexpected findings in this high-risk group vs. the lowrisk group is 12.70 (95% CI 2.8–56.8). Changes in anesthesia technique or supportive actions only happened in this high-risk group. The most common unexpected pathology was pleural effusion, found in 14% (95% CI 8–22) of all patients accounting for 53% (95% CI 34–72) of unex-
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pected findings. Pleural effusion was more often found in patients undergoing surgery for biliary tract infections than in patients undergoing surgery for other reasons (P = 0.031). Pleural effusion tended to be more often found in patients with known heart failure or chronic renal failure than in the remaining patients (P = 0.05). Quantification of the amount of pleural effusion in relation to operation indication and comorbidities in the individual patients can be seen in Table 6. Data on mortality and post-operative length of stay for patients with and without unexpected pathology is given in Table 7.
Table 2 Indications for surgery in patients undergoing urgent surgical procedures. Surgical indication
Patients (n = 112)
Abdominal Suspected gastrointestinal bleeding Abscess – abdominal, axillary, and inguinal Biliary tract infections Change of vacuum system Small abdominal procedures Cancer Gall bladder stones or cholestasis, no infection Ileus/gastrointestinal obstruction Appendicitis Suspected peritonitis Gynecological hemorrhage Orthopedic Hip fractures Other limb fractures Small orthopedic procedures Peripheral arterial disease or revision Removal of osteosynthesis material Total
55 (49%) 10 10 8 7 6 4 3 2 2 2 1 57 (51%) 18 17 12 7 3 10
Discussion In the present study, routine focused ultrasonography disclosed unexpected pathology in 27% of patients undergoing urgent surgical procedures. There was a change in the anesthesia technique or an initiation of supportive actions in 43% of these patients. Our study stands out from previous studies as focused ultrasonography was applied to an unselected group of patients undergoing urgent surgical procedures.6,7 The most frequent unexpected pathology was pleural effusion. Pleural effusion was frequently found in patients undergoing surgery for biliary tract infections. This finding may be because of an inflammatory response across the diaphragm causing effusion. As could be expected, pleural effusion was more frequent in patients with either known heart
Table 3 Numbers of known and unexpected pathological findings. Finding
Total
Known
Unexpected
Pericardial effusion Dilated LV Dilated RV TAPSE < 16 mm Isolated LV hypertrophy LV hypertrophy and dilated LA EF < 40% Aortic sclerosis, without stenosis Aortic sclerosis and stenosis Other obvious pathology Pleural effusion
2 0 1 2 5 4 3 14 2 4 16
0 0 1 2 2 0 3 4 1 3 0
2 0 0 0 3 4 0 10 1 1 16
The same patient can have more than one finding. EF, ejection fraction; LA, left atrium; LV, left ventricle; RV, right ventricle; TAPSE, tricuspid plane anular systolic excursion.
Table 4 Changes in anesthesia technique or supportive action. Unexpected finding
Surgical indication
Changes
Aortic stenosis Pleural effusion Pleural effusion Pleural effusion Pleural effusion Hypovolemia Hypertrophy, dilated LA Pleural effusion Pleural effusion Pleural effusion Hypertrophy dilated LA Hypertrophy, dilated LA and pleural effusion Pleural effusion
Hip fracture Wound infection Change of VAC system Hematemesis Cholecystitis Peritonealia Hip fracture Cholecystitis Rectal bleeding Gangrenous foot Hip fracture Suspected peritonitis
Converted from spinal to general anesthesia Increased PEEP, post-operative CPAP Increased PEEP, post-operative CPAP Post-operative CPAP Increased PEEP, post-operative CPAP Volume infusion Dose reduction of marcain, invasive blood pressure monitoring Increased PEEP, post-operative CPAP Drainage, procedure postponed Drainage before procedure Dose reduction of marcain, invasive blood pressure monitoring Drainage, increased PEEP, post-operative CPAP
Post-operative bleeding
Increased PEEP, post-operative CPAP
CPAP, constant positive airway pressure; LA, left atrium; PEEP, positive end expiratoy pressure; VAC, vacuum.
4
Pre-operative focused ultrasonography A
B RV
LV Hypertrophy
RV LV
AO RA
LA
LV
Dilated LA
LA
D
C
Sclerotic AV
Tip of lung
Liver PLE
VC
Table 5 2 × 2 table, unexpected pathology in low- and high-risk group. No unexpected Unexpected Total pathology pathology Age < 60 and ASA 1–2 39 Age ≥ 60 and/or ASA 3–4 43 Total 82 Fisher’s exact test
2 28 30 P < 0.001
41 71 112
ASA, American Society of Anesthesiologists physical status classification.
failure or known chronic renal failure. In animal models, massive pleural effusion causes hemodynamic depression mimicking cardiac tamponade and drainage of the effusion reverses this effect.13,14 Whether or not this is applicable to humans is not well described, but a recent study supports this.15 In addition, drainage of the effusion in patients with respiratory compromise improves long-term oxygenation.16 As no intervention was protocolized or recommended by the study group, the decision to drain was on the discretion of the individual anesthesiologist responsible for the patient. In the three patients where drainage was chosen, there was more than 5 cm of pleural effusion, corresponding to more than 1000 ml. There is a shortage of evidence on the effect of pleural effusion in anesthesia and patients undergoing surgery. We can only speculate on the effect of positive end expiratory pressure (PEEP) and/or continuous positive airway pressure
Fig. 2. Examples of cardiopulmonary pathology disclosed by focused ultrasonography in patients undergoing urgent surgical procedures. (A, B) Two-dimensional signs of diastolic dysfunction – hypertrophic left ventricle and dilated left atrium. (C) Massive pleural effusion. (D) Aortic calcification/sclerosis. AO, aorta; AV, aortic valve; LA, left atrium; LV, left ventricle; PLE, pleural effusion; RA, right atrium; RV, right ventricle; VC, vertebral column.
(CPAP) treatment that was chosen by some anesthesiologists. Although not directly translatable to our population, CPAP increases post-operative arterial oxygenation in patients undergoing coronary artery bypass graft surgery.17–20 The effect, however, appears to cease when the treatment is discontinued and the methods are incapable of preventing atelectasis.17–20 In addition, the relation between pleural effusion and PEEP/CPAP and oxygenation depends on factors like cardiac filling, volume status, and etiology of effusion. Again, interventions were on the discretion of the individual anesthesiologist, and it is questionable whether CPAP alters outcome in patients with pleural effusion undergoing urgent surgical procedures. These interventions might represent a Hawthorn-like effect induced by the study, and this is a potential source of bias falsely increasing the number of changes in anesthesia technique or supportive actions. Aortic valve sclerosis was the second most frequent unexpected finding. Although not leading to hemodynamic compromise, aortic valve sclerosis is associated with an increased risk of death from other cardiovascular causes such as myocardial infarction and congestive heart failure.21,22 This may indicate an increased perioperative risk in patients with aortic valve sclerosis, and the finding might be valuable for risk stratification. Both moderate and severe aortic valve stenosis are well-described risk factors in noncardiac surgery, and perioperative complications in patients with aortic valve stenosis are frequent.23,24 In this study, an unexpected aortic
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M. T. Bøtker et al. Table 6 Quantification of effusion in patients with unexpected pleural effusion. OP indication
Known comorbidities
Other unexpected pathologies
PLE dxt.
PLE sin.
Hematemesis
Pericardial effusion
None
3.6 cm (≈ 720 ml)
Cholecystitis Colles fracture
AV stenosis, stroke, IHD, COLD, hypertension None Hypertension
None 2.2 cm (≈ 440 ml)
3.6 cm (≈ 720 ml) 1.8 cm (≈ 360 ml)
Pancreatitis Exchange of VAC Exchange of VAC Orthopedic wound revision Post-operative bleeding Peritonalia
None Hypertension Hypertension, asthma Chronic renal failure None Hypertension
None None None 2.0 cm (≈ 400 ml) 2.0 cm (≈ 400 ml) 5.1 cm (≈ 1020 ml)
1.2 cm 2.3 cm 2.4 cm None 2.5 cm 3.4 cm
Cholangitis Suspected GI bleeding
IHD, heart failure Chronic renal failure, AFLI, hypertension None AFLI Heart failure, AV sclerosis, IHD, hypertension AFLI, COLD Hypertension
None Diastolic dysfunction, AV sclerosis None None None None None Diastolic dysfunction, AV sclerosis None Aortic valve sclerosis
1.2 cm (≈ 240 ml) 6.3 cm (≈ 1260 ml)
None 5.0 cm (≈ 1000 ml)
None None None
None 2.0 cm (≈ 400 ml) 3.2 cm (≈ 640 ml)
2.8 cm (≈ 360 ml) None None
None None
6.4 cm (≈ 1280 ml) None
None 1.6 cm (≈ 320 ml)
Exchange of VAC Hip fracture Peripheral arterial disease Peripheral arterial disease Cholecystitis
(≈ 240 ml) (≈ 460 ml) (≈ 480 ml) (≈ 500 ml) (≈ 680 ml)
Quantification of amounts of pleural effusion is based on a published study.12 AFLI, atrial fibrillation; AV, aortic valve; COLD, chronic obstructive pulmonary disorder; GI, gastrointestinal; IHD, ischemic heart disease; OP, operation; PLE, pleural effusion; VAC, vacuum system.
Table 7 Mortality and length of stay in patients undergoing urgent surgical procedures with and without unexpected pathology by FATE. Dead in hospital Dead within 30 days Post-operative LOS (d)
Unexpected pathology, n = 30
No unexpected pathology, n = 82
Significance
4 (13%) 5 (17%) 3.4
0 (0%) 1 (1%) 1.9
P < 0.005 P = 0.005 P = 0.078
FATE, Focus Assessed Transthoracic Echocardiography; LOS, length-of-stay.
valve stenosis was disclosed in one patient undergoing hip fracture surgery, and general anesthesia was chosen over spinal anesthesia. We defined the combination of left ventricular hypertrophy and a dilated left atrium as indirect two-dimensional signs of diastolic dysfunction. This is based on the relationship between left atrial size and the severity of diastolic dysfunction, on expert opinions, and on recommendations.11,25,26 Patients with diastolic dysfunction have a higher myocardial oxygen demand and a reduced coronary flow reserve.27 This causes susceptibility to hypotension or arrhythmia because myocardial ischemia induces a vicious circle worsening the hypotension.28 A lower induction dose and a step up in monitoring, often chosen by the anesthesiologists, may have prevented perioperative complications. Routine focused cardiopulmonary ultrasonography is a fast, effective way of detecting unknown
6
pathology of consequence to choice of anesthesia technique and supportive actions. Nevertheless, focused ultrasonography by nonspecialists inherits a risk of both false negative findings and false positive findings and thus iatrogenic complications – especially in younger low-risk patients. Our data do not support the use of focused ultrasonography in young, healthy individuals. But, based on our data, routine use could be feasible for a group of patients over the age of 60 years and and/or in ASA class ≥ 3 undergoing urgent surgical procedures. Even if the cases of minor pleural effusion that led to CPAP treatment are discarded, focused ultrasonography led to a change in choice of anesthesia technique or supportive efforts in 10% of patients in this high-risk group. Our data, however, cannot be used to conclude that focused ultrasonography improves outcome and whether or not routine use in these high-risk patients reduces perioperative complica-
Pre-operative focused ultrasonography
tions and improves outcome is unknown. A recent historically controlled study suggests that preoperative focused transthoracic echocardiography is associated with lower mortality in high-risk patients undergoing hip fracture surgery compared with patients not undergoing echocardiography.29 This could be a focus for randomized controlled trials. Another focus in future studies on nonexpert focused ultrasonography should be validation of findings by experts in echocardiography and/or ultrasonography.
Limitations of the study A relatively high number of patients were excluded from the study. The majority of patients were excluded because they were taken to the operating room before FATE examination could be done. The exclusions might have led to an underestimation of unexpected pathological findings but are not expected to affect the overall results. As stated, some interventions may be caused by a Hawthornlike effect and introduce bias. Because of the number of patients included in the study and the number of events, we are not able to adjust for confounders or bias by logistic regression. Thus, we cannot conclude on causal relations among FATE, change in technique, or supportive actions and outcome. It is also a limitation that we do not have detailed description of the routine pre-operative assessment, for example, whether or not auscultation was actually performed. However, in our setting auscultation is generally a standard operating procedure in relation to pre-operative assessment. Unexpected findings refer to findings that were not disclosed in the routine pre-operative assessment and the comparison thus is ‘business as usual’ vs. ‘business as usual supplemented by focused ultrasonography’. In conclusion, focused cardiopulmonary ultrasonography performed by anesthesiologists disclosed unexpected pathology in 27% of patients undergoing urgent surgical procedures. Unexpected pathology led to a change in anesthesia technique or supportive actions in 43% of these patients. Both unexpected pathology and changes in anesthetic technique or supportive actions occurred more often in a group of patients above the age of 60 years or in ASA class above 2. This high-risk group could be of interest in future studies on patientcentered outcome measures. Focused ultrasonography does not seem feasible in young, healthy individuals undergoing surgery.
Acknowledgements The study was funded by The Department of Anesthesiology and Intensive Care at the Regional Hospital of Randers, Denmark, and by The John and Birthe Meyer Foundation. Conflicts of interests: Erik Sloth is co-owner of USABCD A/S providing the e-learning used.
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Address: Morten Thingemann Bøtker Department of Anesthesiology and Intensive Care Regional Hospital of Randers Skovlyvej 1 8930 Randers Denmark e-mail: [email protected]
© 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd ACTA ANAESTHESIOLOGICA SCANDINAVICA
doi: 10.1111/aas.12343
Routine pre-operative focused ultrasonography by anesthesiologists in patients undergoing urgent surgical procedures M. T. Bøtker1,2, M. L. Vang1, T. Grøfte1, E. Sloth3 and C. A. Frederiksen4
1 Department of Anesthesiology and Intensive Care, Regional Hospital of Randers, Randers, Denmark, 2Research Center for Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark, 3Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Aarhus, Denmark and 4Department of Internal Medicine, Regional Hospital of Randers, Randers, Denmark
Background: Unexpected cardiopulmonary complications are well described during surgery and anesthesia. Pre-operative evaluation by focused cardiopulmonary ultrasonography may prevent such mishaps. The aim of this study was to determine the frequency of unexpected cardiopulmonary pathology with focused ultrasonography in patients undergoing urgent surgical procedures. Methods: We performed pre-operative focused cardiopulmonary ultrasonography in patients aged 18 years or above undergoing urgent surgical procedures at pre-defined study days. Known and unexpected cardiopulmonary pathology was recorded, and subsequent changes in the anesthesia technique or supportive actions were registered. Results: A total of 112 patients scheduled for urgent surgical procedures were included. Their mean age (standard deviation) was 62 (21) years. Of these patients, 24% were American Society of Anesthesiologists (ASA) class 1, 39% were ASA class 2, 32% were ASA class 3, and 4% were ASA class 4. Unexpected car-
C
ardiopulmonary complications are well described during general and regional anesthesia, and emergency surgery and cardiac disease are independent predictors of mortality.1–4 In order to exclude all cardiac and pulmonary pathology, pre-operative examination may have to be expanded to include pulmonary function testing, coronary arteriography, full echocardiography, and computed tomography of the thorax. This, however, is neither necessary nor feasible, and guidelines suggest that pre-operative testing should be conducted only on indication.1,5 Pre-operative expert echocardiography discloses significant pathology in patients with suspected heart disease undergoing noncardiac surgery, and this often leads to changes in perioperative management.6,7 This is especially the case in patients undergoing emergency
diopulmonary pathology was disclosed in 27% [95% confidence interval (CI) 19–36] of the patients and led to a change in anesthesia technique or supportive actions in 43% (95% CI 25–63) of these. Unexpected pathology leading to changes in anesthesia technique or supportive actions was only disclosed in a group of patients above the age of 60 years and/or in ASA class ≥ 3. Conclusion: Focused cardiopulmonary ultrasonography disclosed unexpected pathology in patients undergoing urgent surgical procedures and induced changes in the anesthesia technique or supportive actions. Pre-operative focused ultrasonography seems feasible in patients above 60 year and/or with physical limitations but not in young, healthy individuals. Accepted for publication 27 April 2014 © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd
noncardiac surgery.7 These findings are all in accordance with current guidelines, but the use of focused ultrasonography is increasing – especially in anesthesiology and critical care. There is little evidence to support this development, and it is questionable if all pathology needs to be disclosed before anesthesia. Nevertheless, in patients undergoing emergency surgery, time is limited and focused ultrasonography may add additional knowledge of importance to the anesthesia that would otherwise not be disclosed. In order to identify patients that may benefit from focused ultrasonography, we have to examine an unselected cohort undergoing surgery. Focus Assessed Transthoracic Echocardiography (FATE) is a protocol designed to evaluate the hemodynamic and respiratory function, and to
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detect significant cardiovascular and pulmonary pathology by visualization of the heart and the pleura.8 The protocol is easy to learn, and a FATE examination can be completed in less than 2 min.9,10 We hypothesized that unexpected cardiovascular and pulmonary pathology is frequent in unselected patients undergoing urgent surgical procedures and may be discovered by FATE examination. The objective of this study was to quantify unexpected cardiopulmonary pathology by focused ultrasonography in unselected patients undergoing urgent surgical procedures and to evaluate the impact of unexpected pathology on choice of anesthesia technique or supportive actions.
Methods Setting and study population We conducted this prospective cohort study on 24 pre-defined study days from 10 October 2012 to 17 January 2013 at the Regional Hospital of Randers, Denmark. All patients at least 18 years of age undergoing acute orthopedic or abdominal surgery were included. Patients not able or willing to give informed consent and patients previously included in the study were excluded. Logistic reasons also necessitated exclusion of a number of patients (either patients were brought to the operating room while examination of another patient was ongoing or patients had incomplete examinations because they were taken to the operating room immediately). The Central Denmark Region Committee on Biomedical and Research Ethics reviewed the study, and because of the study design, it was exempt from formal ethical approval. We obtained written informed consent from all study participants.
Education and equipment All 24 anesthesiologists, both residents and consultants, at the Regional Hospital of Randers were systematically trained in the FATE protocol in connection with this study. The educational program comprised an e-learning module, a hands-on course, and 10 supervised real-time examinations. The 10 supervised examinations were carried out on 24 pre-defined study days. It was on these days that eligible patients were included. The anesthesiologists in training were real-time supervised by one of two experienced FATE supervisors (both anesthesiologists) who also interpreted the examinations and did the registration. If additional imaging, like extended FATE views and Doppler evaluation, was needed, the supervisors carried this out. We used
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a Vivid S6 (GE Healthcare, Horten, Norway) system equipped with a M4S phased array transducer (1.5– 4.0 MHz).
Examinations and interpretation Patients underwent pre-operative FATE examination at the bedside. Examinations were interpreted according to dichotomous outcomes and cutoff values. Cutoff values were in accordance with recommendations made by the American Society of Echocardiography and the European Association of Echocardiography.11 We assessed the following outcome criteria: 1. Pericardial effusion ≥ 10 mm present? 2. Left ventricle end diastolic diameter ≥ 6.2 cm, indicating left ventricle dilation? 3. Mid right ventricle end diastolic diameter ≥ 42 mm or tricuspid anular plane systolic excursion ≤ 16 mm, indicating right ventricle dilation or systolic dysfunction? 4. Left ventricle septal or posterior wall thickness ≥ 13 mm? In case hypertrophy was present, we assessed whether left atrium diameter was > 50 mm, indicating diastolic dysfunction. 5. Ejection fraction ≤ 40% by eyeballing, indicating left ventricle systolic dysfunction? 6. Visible aortic valve sclerosis? In case sclerosis was present, supervisors assessed whether maximum jet velocity over the aortic valve by Continuous Wave Doppler was ≥ 3 m/s, indicating aortic stenosis. 7. Other obvious pathological findings, processes or excrescences present? 8. Any pleural effusion present? Pathology was registered as known or unexpected based on whether it was encountered by the preceding routine pre-operative evaluation or not. In case of unexpected pathology, the anesthesiologist who had conducted the routine pre-operative evaluation was informed. No interventions were protocolized or recommended by the study group. If the anesthesiologist handling the patient made a change in the anesthesia technique or initiated supportive actions based on this new information, this was registered. In patients requiring full echocardiography by a cardiologist according to guidelines (i.e. known or suspected valve disease and/or clinical suspicion of heart failure), this was performed in accordance with standard procedures. The findings of the full echocardiography were registered as known findings, but focused ultrasonography was also performed, because a classical echocardiography rarely
Pre-operative focused ultrasonography
includes a pleural scan. Quantification of the amount of pleural effusion was done post hoc based on the findings in a recent study in intensive care patients where the pleural scan is carried out with the patient in the supine position as it is done in the FATE examination.12
Met the inclusion criteria (n = 160)
Excluded (n = 48) • Logistical reasons (n = 35) • Lack of informed consent (n = 8) • Previously included (n = 5)
Statistical analysis The primary endpoint was unexpected cardiopulmonary pathology overall. The secondary endpoints were (1) unexpected cardiopulmonary pathology in subgroups of patients based on age and American Society of Anesthesiologists (ASA) physical status classification and (2) changes in anesthesia technique or supportive actions overall and in subgroups. Inherent to the study design, there was no loss to follow-up. We used Fisher’s exact test to compare the proportion of unexpected pathology in subgroups of patients. We calculated odds ratios using Woolf’s method. We used Wilcoxon rank-sum test to compare length of stays. Primary and secondary endpoints are presented as proportions with 95% confidence intervals (CIs). Based on a previously published study, we considered 10% unexpected pathology to be a clinically relevant proportion.3 Based on the assumption, that only very few patients undergoing urgent surgical procedures suffer from unexpected cardiopulmonary disease, we defined a postulated value of 2%. With a power of 0.90 and a significance level of 0.05, we thus needed to include 93 patients. STATA software (StataCorp LP, College Station, TX, USA) was used for all statistical calculations.
Results On the study days, 160 patients underwent urgent surgical procedures; 48 patients were excluded (Fig. 1). A total of 112 patients were included in the study. Baseline characteristics are shown in Table 1, and indication for surgery is shown in Table 2. Pathology was disclosed in 32% (95% CI 24–42) of patients, and 27% (95% CI 19–36) had unexpected pathology (Table 3). In 12% (95% CI 6–18) of the total cohort, focused ultrasonography led to a change in anesthesia technique or supportive actions (Table 4). This corresponds to a change in anesthesia technique or supportive action among 43% (95% CI 25–63) of patients with unexpected pathology. Examples of unexpected pathology are depicted in Fig. 2. There was a higher proportion of unexpected pathology (P < 0.001) among patients above the age
Included in the study (n = 112)
Fig. 1. Patients undergoing urgent surgical procedures excluded from the study.
Table 1 Baseline characteristics for patients undergoing urgent surgical procedures. Characteristic
Patients (n = 112)
Age, years Male ASA physical status class 1 2 3 4 5 6 Ischemic heart disease Heart failure Atrial fibrillation Peripheral arterial disease Aortic valve stenosis Artificial aortic valve Stroke Chronic obstructive pulmonary disorder Asthma Arterial hypertension Hypercholesterolemia Diabetes mellitus Chronic renal failure
62 ± 21 60 (54%) 27 (24%) 44 (39%) 36 (32%) 5 (5%) 0 (0%) 0 (0%) 10 (9%) 5 (4%) 15 (13%) 8 (7%) 1 (1%) 1 (1%) 3 (3%) 10 (9%) 4 (4%) 51 (46%) 21 (19%) 18 (16%) 6 (5%)
ASA, American Society of Anesthesiologists.
of 60 years and/or in ASA class ≥ 3 than in the remaining study population (Table 5). In this highrisk group, unexpected pathology occurred in 39% (95% CI 28–52) of patients. Odds ratio for unexpected findings in this high-risk group vs. the lowrisk group is 12.70 (95% CI 2.8–56.8). Changes in anesthesia technique or supportive actions only happened in this high-risk group. The most common unexpected pathology was pleural effusion, found in 14% (95% CI 8–22) of all patients accounting for 53% (95% CI 34–72) of unex-
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pected findings. Pleural effusion was more often found in patients undergoing surgery for biliary tract infections than in patients undergoing surgery for other reasons (P = 0.031). Pleural effusion tended to be more often found in patients with known heart failure or chronic renal failure than in the remaining patients (P = 0.05). Quantification of the amount of pleural effusion in relation to operation indication and comorbidities in the individual patients can be seen in Table 6. Data on mortality and post-operative length of stay for patients with and without unexpected pathology is given in Table 7.
Table 2 Indications for surgery in patients undergoing urgent surgical procedures. Surgical indication
Patients (n = 112)
Abdominal Suspected gastrointestinal bleeding Abscess – abdominal, axillary, and inguinal Biliary tract infections Change of vacuum system Small abdominal procedures Cancer Gall bladder stones or cholestasis, no infection Ileus/gastrointestinal obstruction Appendicitis Suspected peritonitis Gynecological hemorrhage Orthopedic Hip fractures Other limb fractures Small orthopedic procedures Peripheral arterial disease or revision Removal of osteosynthesis material Total
55 (49%) 10 10 8 7 6 4 3 2 2 2 1 57 (51%) 18 17 12 7 3 10
Discussion In the present study, routine focused ultrasonography disclosed unexpected pathology in 27% of patients undergoing urgent surgical procedures. There was a change in the anesthesia technique or an initiation of supportive actions in 43% of these patients. Our study stands out from previous studies as focused ultrasonography was applied to an unselected group of patients undergoing urgent surgical procedures.6,7 The most frequent unexpected pathology was pleural effusion. Pleural effusion was frequently found in patients undergoing surgery for biliary tract infections. This finding may be because of an inflammatory response across the diaphragm causing effusion. As could be expected, pleural effusion was more frequent in patients with either known heart
Table 3 Numbers of known and unexpected pathological findings. Finding
Total
Known
Unexpected
Pericardial effusion Dilated LV Dilated RV TAPSE < 16 mm Isolated LV hypertrophy LV hypertrophy and dilated LA EF < 40% Aortic sclerosis, without stenosis Aortic sclerosis and stenosis Other obvious pathology Pleural effusion
2 0 1 2 5 4 3 14 2 4 16
0 0 1 2 2 0 3 4 1 3 0
2 0 0 0 3 4 0 10 1 1 16
The same patient can have more than one finding. EF, ejection fraction; LA, left atrium; LV, left ventricle; RV, right ventricle; TAPSE, tricuspid plane anular systolic excursion.
Table 4 Changes in anesthesia technique or supportive action. Unexpected finding
Surgical indication
Changes
Aortic stenosis Pleural effusion Pleural effusion Pleural effusion Pleural effusion Hypovolemia Hypertrophy, dilated LA Pleural effusion Pleural effusion Pleural effusion Hypertrophy dilated LA Hypertrophy, dilated LA and pleural effusion Pleural effusion
Hip fracture Wound infection Change of VAC system Hematemesis Cholecystitis Peritonealia Hip fracture Cholecystitis Rectal bleeding Gangrenous foot Hip fracture Suspected peritonitis
Converted from spinal to general anesthesia Increased PEEP, post-operative CPAP Increased PEEP, post-operative CPAP Post-operative CPAP Increased PEEP, post-operative CPAP Volume infusion Dose reduction of marcain, invasive blood pressure monitoring Increased PEEP, post-operative CPAP Drainage, procedure postponed Drainage before procedure Dose reduction of marcain, invasive blood pressure monitoring Drainage, increased PEEP, post-operative CPAP
Post-operative bleeding
Increased PEEP, post-operative CPAP
CPAP, constant positive airway pressure; LA, left atrium; PEEP, positive end expiratoy pressure; VAC, vacuum.
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Pre-operative focused ultrasonography A
B RV
LV Hypertrophy
RV LV
AO RA
LA
LV
Dilated LA
LA
D
C
Sclerotic AV
Tip of lung
Liver PLE
VC
Table 5 2 × 2 table, unexpected pathology in low- and high-risk group. No unexpected Unexpected Total pathology pathology Age < 60 and ASA 1–2 39 Age ≥ 60 and/or ASA 3–4 43 Total 82 Fisher’s exact test
2 28 30 P < 0.001
41 71 112
ASA, American Society of Anesthesiologists physical status classification.
failure or known chronic renal failure. In animal models, massive pleural effusion causes hemodynamic depression mimicking cardiac tamponade and drainage of the effusion reverses this effect.13,14 Whether or not this is applicable to humans is not well described, but a recent study supports this.15 In addition, drainage of the effusion in patients with respiratory compromise improves long-term oxygenation.16 As no intervention was protocolized or recommended by the study group, the decision to drain was on the discretion of the individual anesthesiologist responsible for the patient. In the three patients where drainage was chosen, there was more than 5 cm of pleural effusion, corresponding to more than 1000 ml. There is a shortage of evidence on the effect of pleural effusion in anesthesia and patients undergoing surgery. We can only speculate on the effect of positive end expiratory pressure (PEEP) and/or continuous positive airway pressure
Fig. 2. Examples of cardiopulmonary pathology disclosed by focused ultrasonography in patients undergoing urgent surgical procedures. (A, B) Two-dimensional signs of diastolic dysfunction – hypertrophic left ventricle and dilated left atrium. (C) Massive pleural effusion. (D) Aortic calcification/sclerosis. AO, aorta; AV, aortic valve; LA, left atrium; LV, left ventricle; PLE, pleural effusion; RA, right atrium; RV, right ventricle; VC, vertebral column.
(CPAP) treatment that was chosen by some anesthesiologists. Although not directly translatable to our population, CPAP increases post-operative arterial oxygenation in patients undergoing coronary artery bypass graft surgery.17–20 The effect, however, appears to cease when the treatment is discontinued and the methods are incapable of preventing atelectasis.17–20 In addition, the relation between pleural effusion and PEEP/CPAP and oxygenation depends on factors like cardiac filling, volume status, and etiology of effusion. Again, interventions were on the discretion of the individual anesthesiologist, and it is questionable whether CPAP alters outcome in patients with pleural effusion undergoing urgent surgical procedures. These interventions might represent a Hawthorn-like effect induced by the study, and this is a potential source of bias falsely increasing the number of changes in anesthesia technique or supportive actions. Aortic valve sclerosis was the second most frequent unexpected finding. Although not leading to hemodynamic compromise, aortic valve sclerosis is associated with an increased risk of death from other cardiovascular causes such as myocardial infarction and congestive heart failure.21,22 This may indicate an increased perioperative risk in patients with aortic valve sclerosis, and the finding might be valuable for risk stratification. Both moderate and severe aortic valve stenosis are well-described risk factors in noncardiac surgery, and perioperative complications in patients with aortic valve stenosis are frequent.23,24 In this study, an unexpected aortic
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M. T. Bøtker et al. Table 6 Quantification of effusion in patients with unexpected pleural effusion. OP indication
Known comorbidities
Other unexpected pathologies
PLE dxt.
PLE sin.
Hematemesis
Pericardial effusion
None
3.6 cm (≈ 720 ml)
Cholecystitis Colles fracture
AV stenosis, stroke, IHD, COLD, hypertension None Hypertension
None 2.2 cm (≈ 440 ml)
3.6 cm (≈ 720 ml) 1.8 cm (≈ 360 ml)
Pancreatitis Exchange of VAC Exchange of VAC Orthopedic wound revision Post-operative bleeding Peritonalia
None Hypertension Hypertension, asthma Chronic renal failure None Hypertension
None None None 2.0 cm (≈ 400 ml) 2.0 cm (≈ 400 ml) 5.1 cm (≈ 1020 ml)
1.2 cm 2.3 cm 2.4 cm None 2.5 cm 3.4 cm
Cholangitis Suspected GI bleeding
IHD, heart failure Chronic renal failure, AFLI, hypertension None AFLI Heart failure, AV sclerosis, IHD, hypertension AFLI, COLD Hypertension
None Diastolic dysfunction, AV sclerosis None None None None None Diastolic dysfunction, AV sclerosis None Aortic valve sclerosis
1.2 cm (≈ 240 ml) 6.3 cm (≈ 1260 ml)
None 5.0 cm (≈ 1000 ml)
None None None
None 2.0 cm (≈ 400 ml) 3.2 cm (≈ 640 ml)
2.8 cm (≈ 360 ml) None None
None None
6.4 cm (≈ 1280 ml) None
None 1.6 cm (≈ 320 ml)
Exchange of VAC Hip fracture Peripheral arterial disease Peripheral arterial disease Cholecystitis
(≈ 240 ml) (≈ 460 ml) (≈ 480 ml) (≈ 500 ml) (≈ 680 ml)
Quantification of amounts of pleural effusion is based on a published study.12 AFLI, atrial fibrillation; AV, aortic valve; COLD, chronic obstructive pulmonary disorder; GI, gastrointestinal; IHD, ischemic heart disease; OP, operation; PLE, pleural effusion; VAC, vacuum system.
Table 7 Mortality and length of stay in patients undergoing urgent surgical procedures with and without unexpected pathology by FATE. Dead in hospital Dead within 30 days Post-operative LOS (d)
Unexpected pathology, n = 30
No unexpected pathology, n = 82
Significance
4 (13%) 5 (17%) 3.4
0 (0%) 1 (1%) 1.9
P < 0.005 P = 0.005 P = 0.078
FATE, Focus Assessed Transthoracic Echocardiography; LOS, length-of-stay.
valve stenosis was disclosed in one patient undergoing hip fracture surgery, and general anesthesia was chosen over spinal anesthesia. We defined the combination of left ventricular hypertrophy and a dilated left atrium as indirect two-dimensional signs of diastolic dysfunction. This is based on the relationship between left atrial size and the severity of diastolic dysfunction, on expert opinions, and on recommendations.11,25,26 Patients with diastolic dysfunction have a higher myocardial oxygen demand and a reduced coronary flow reserve.27 This causes susceptibility to hypotension or arrhythmia because myocardial ischemia induces a vicious circle worsening the hypotension.28 A lower induction dose and a step up in monitoring, often chosen by the anesthesiologists, may have prevented perioperative complications. Routine focused cardiopulmonary ultrasonography is a fast, effective way of detecting unknown
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pathology of consequence to choice of anesthesia technique and supportive actions. Nevertheless, focused ultrasonography by nonspecialists inherits a risk of both false negative findings and false positive findings and thus iatrogenic complications – especially in younger low-risk patients. Our data do not support the use of focused ultrasonography in young, healthy individuals. But, based on our data, routine use could be feasible for a group of patients over the age of 60 years and and/or in ASA class ≥ 3 undergoing urgent surgical procedures. Even if the cases of minor pleural effusion that led to CPAP treatment are discarded, focused ultrasonography led to a change in choice of anesthesia technique or supportive efforts in 10% of patients in this high-risk group. Our data, however, cannot be used to conclude that focused ultrasonography improves outcome and whether or not routine use in these high-risk patients reduces perioperative complica-
Pre-operative focused ultrasonography
tions and improves outcome is unknown. A recent historically controlled study suggests that preoperative focused transthoracic echocardiography is associated with lower mortality in high-risk patients undergoing hip fracture surgery compared with patients not undergoing echocardiography.29 This could be a focus for randomized controlled trials. Another focus in future studies on nonexpert focused ultrasonography should be validation of findings by experts in echocardiography and/or ultrasonography.
Limitations of the study A relatively high number of patients were excluded from the study. The majority of patients were excluded because they were taken to the operating room before FATE examination could be done. The exclusions might have led to an underestimation of unexpected pathological findings but are not expected to affect the overall results. As stated, some interventions may be caused by a Hawthornlike effect and introduce bias. Because of the number of patients included in the study and the number of events, we are not able to adjust for confounders or bias by logistic regression. Thus, we cannot conclude on causal relations among FATE, change in technique, or supportive actions and outcome. It is also a limitation that we do not have detailed description of the routine pre-operative assessment, for example, whether or not auscultation was actually performed. However, in our setting auscultation is generally a standard operating procedure in relation to pre-operative assessment. Unexpected findings refer to findings that were not disclosed in the routine pre-operative assessment and the comparison thus is ‘business as usual’ vs. ‘business as usual supplemented by focused ultrasonography’. In conclusion, focused cardiopulmonary ultrasonography performed by anesthesiologists disclosed unexpected pathology in 27% of patients undergoing urgent surgical procedures. Unexpected pathology led to a change in anesthesia technique or supportive actions in 43% of these patients. Both unexpected pathology and changes in anesthetic technique or supportive actions occurred more often in a group of patients above the age of 60 years or in ASA class above 2. This high-risk group could be of interest in future studies on patientcentered outcome measures. Focused ultrasonography does not seem feasible in young, healthy individuals undergoing surgery.
Acknowledgements The study was funded by The Department of Anesthesiology and Intensive Care at the Regional Hospital of Randers, Denmark, and by The John and Birthe Meyer Foundation. Conflicts of interests: Erik Sloth is co-owner of USABCD A/S providing the e-learning used.
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Address: Morten Thingemann Bøtker Department of Anesthesiology and Intensive Care Regional Hospital of Randers Skovlyvej 1 8930 Randers Denmark e-mail: [email protected]
