Abstracts submitted to ACTA Cambridge 20 June 2003
1 of 12
Tracheostomy practice on a cardiothoracic intensive care unit
Briggs S, Ambler J, Smith D.
Department of Anaesthesia, Southampton General Hospital, Tremona Road,
Southampton, SO16 6YD, UK.
Introduction: Tracheostomies are frequently formed in intensive care patients. The
perceived benefits are reduction in work of breathing, reduction in sedation, and
increase in communication. It is a maximally invasive procedure, and the
consequences of error can be rapidly life threatening. Similarly, day-to-day usage,
although usually straightforward, can become complicated, with disastrous
consequences [1]. We examine a series of one hundred tracheostomies formed in
patients on the cardiothoracic intensive care unit, to assess current practice,
complication rates, and identify areas of clinical practice that could be improved.
Methods: We selected the most recent series of one hundred tracheostomies that
were formed in patients on the unit, and reviewed the case notes retrospectively. We
looked at reasons why tracheostomies are formed, the time course of events, the
seniority of clinicians performing the procedures, procedure details, and occurrence
of complications until the tracheostomy was either removed or the patient died.
Results: A total of 95 patients each had one tracheostomy formed, whilst one
patient had the tracheostomy formed twice, and one patient had the tracheostomy
formed three times. Six sets of notes were entirely missing whilst nine sets were
partially missing. The median time from endotracheal intubation to tracheostomy
formation was 5 days (25th percentile 4 days, 75th percentile 8 days), and median
period between insertion and decannulation was 20 days (25 th percentile 12 days,
75th percentile 25 days). The most common reason for insertion was anticipated long
wean (55% (52/94)), followed by insertion after failed extubation (32% (30/94)).
Registrars are the most frequent operators (66% (62/94). Percutaneous dilatational
techniques were used for 89% (64/72) of tracheostomy formations, whilst surgical
techniques were used for 8% (6/72). The Ciaglia method was used for percutaneous
dilatational trachesotomy formation. A bronchoscope was used to aid placement of
the percutaneous tracheostomy on 94% (63/67) of occasions, whilst direct
laryngoscopy was used alone, on 6% (4/67) of occasions. Upon decannulation,
tracheostomy tubes were replaced with ‘Minitrach tubes’ on 35% (33/94) of
occasions. The most common complication was either complete or partial
obstruction of the tracheostomy tube (24% (23/94)) requiring either removal alone, or
removal and replacement. Infection of the tracheostomy site occurred in 18%
(17/94).
Conclusion: The percutaneous dilatational technique of tracheostomy formation is
used predominantly on our unit. The most common complications are tracheostomy
obstruction and site infection. A significant number of cases have a ‘Minitrach tubes’
inserted following decannulation. In order to improve clinical practice, documentation
of the insertion procedure and complications both on the ICU and ward must be
improved.
Reference: Grover ER, Bihari DJ: The role of tracheostomy in the adult intensive
care unit. Postgrad Med J 1992, 68(799): 313-7.
Abstracts submitted to ACTA Cambridge 20 June 2003
2 of 12
Transoesophageal echocardiography aided endovascular stent-graft repair of
a ruptured aortic aneurysm
S T Clinton, SS Shah, S McPherson, H McKeague
General Infirmary at Leeds, Great George Street, Leeds, LS1 3EX
Introduction Endovascular aortic repair of thoracic aortic pathology is less invasive
and potentially safer than open surgery. Transoesophageal echocardiography
(TOE) provides excellent views of the distal aortic arch, descending thoracic aorta
and can aid stent deployment. We report the use of TOE in the endovascular repair
of a ruptured aortic aneurysm presenting as an aortic-bronchial fistula.
Case report A 68-year-old lady presented to the emergency department with
massive haemoptysis and cardiovascular collapse. She had been recently
diagnosed as having an aneurysm of the distal arch and proximal descending
thoracic aorta. This was believed to have occurred at the site of a previous
transection following significant thoracic trauma 12 years earlier. Her past medical
history included controlled hypertension, poor respiratory function, smoking and
morbid obesity. Following emergency intubation, ventilation and CT scanning, she
was transferred to theatre where endovascular stenting was performed. TOE was
invaluable in localizing the aneurysm, monitoring haemodynamics, and confirming
successful stent placement excluding flow within the sac.
Discussion As thoracic endovascular procedures become more commonplace, the
utility of TOE will become more apparent. TOE provides instantaneous views, which
aid identification of aortic pathology, estimates endograft sizing, guide stent
deployment and confirm exclusion of the aneurysmal sac. It has been shown to be
superior to perioperative angiography both in diagnosing endograft leakage
(sensitivity and specificity of 100 %) and diagnosing iatrogenic dissections [1].
References
1. Kahn RA, Moskowitz DM: Endovascular aortic repair. J Cardiothorac Vasc
Anesth 16:218-233, 2002
Abstracts submitted to ACTA Cambridge 20 June 2003
3 of 12
Optimising Blood Conservation In Cardiac Surgery – A Randomised Double Blind Placebo
Controlled Trial Of Two Anti-Fibrinolytics Used In Addition To Intra-Operative Cell
Salvage
Diprose P, Herbertson M, Deakin CD, O’Shaughnessy D¶, Gill R
Departments of Anaesthesia and Haematology¶, Southampton University Hospitals NHS
Trust, Tremona Road, Southampton, SO16 6YD, UK
Cardiac surgery utilises a large proportion of blood and blood products. The reasons for this
are multi-factorial and include pre-operative anti-platelet therapy, cardiopulmonary bypass
effects and the extent of surgery. Previous work has confirmed that intra-operative cell
salvage (ICS) was the most effective mechanical method of reducing exposure to blood and
blood products.1 Our aim was to ascertain the optimal combined mechanical and
pharmacological methods of blood conservation in cardiac surgery.
Following institutional ethics approval, patients were approached for inclusion into the study
if they presented for first time coronary artery surgery or first time single valve
repair/replacement. Patients were included if they were taking aspirin but excluded if on any
other anti-platelet therapy. Once informed consent had been obtained, patients were
randomised to receive either aprotinin with the standard ‘Hammersmith’ regime (APR
group), 5g Tranexamic acid with equivalent volumes of normal saline (TXA group), or,
equivalent volumes of normal saline as a placebo group (PLA group). All drugs were
prepared and blinded by independent practitioners within the hospital’s pharmacy technical
services unit. All patient groups received intra-operative cell salvage with a standardised
protocol. The trigger for blood transfusion was a haemoglobin of less than 85g/l post-op.
Blood product transfusion was guided by a protocol largely based on previous work by
Shore-Lesserson et al.2 Primary outcome measures were exposure to blood or blood products.
Secondary outcomes were mediastinal drainage and cardiac indicators of myocardial
infarction.
A total of 186 patients were randomised, 180 (60 in each group) of which received the
full treatment regime and were studied. There were no significant differences between groups
in terms of age, Parsonnet score, aspirin usage, procedure performed, cardiopulmonary
bypass or cross clamp times. Exposure to any blood or blood products was significantly less
between anti-fibrinolytic groups and placebo and between aprotinin and tranexamic acid
(proportions given any transfusion : APR 15%, TXA 35%, PLA 60%). Mediastinal drainage
was significantly less in the APR group as compared to either TXA or PLA. There was no
statistically significant difference between groups for the number of patients that required reopening (number re-opened APR=2, TXA=5, PLA=7). No difference was shown between
groups for indicators of myocardial infarction.
Aprotinin in the dosing regime tested is more efficacious than both placebo and 5g of
tranexamic acid in reducing exposure to blood and blood products following first-time
cardiac surgery.
References
1. McGill N, O'Shaughnessy D, Pickering R, Herbertson M, Gill R. Mechanical methods of
reducing blood transfusion in cardiac surgery: randomised controlled trial. BMJ 2002; 324:
1299.
2. Shore-Lesserson L, Manspeizer HE, DePerio M, Francis S, Vela-Cantos F, Ergin MA.
Thromboelastography-guided transfusion algorithm reduces transfusions in complex cardiac
surgery. Anesth Analg. 1999; 88: 312-9
Abstracts submitted to ACTA Cambridge 20 June 2003
4 of 12
The presence of a radiological gastric gas shadow and nausea and vomiting
after cardiac surgery
V Gaur, A Gaur, JLC Swanevelder, RR Govindaswami, U Singh
Department of Cardiology, Department of Anaesthesia and Critical Care, Glenfield
Hospital, University Hospitals of Leicester. Department of Bio-statistic, Sanjay
Ghandi Postgraduate Institute of Medical Sciences, Lucknow, India.
Introduction: The incidence of postoperative nausea and vomiting (PONV) after
cardiac surgery is around 45% reaching 70% in female population. Numerous factors
have been implicated including patient weight, use of nitrous oxide and experience of
anaesthetist. [1, 2] In this prospective audit we investigated the presence of gas in
the stomach on chest X-ray and its correlation with PONV after cardiac surgery.
Methods: We looked for the presence of gas in the stomach on chest X-ray in 27
consecutive patients listed for cardiac surgery. A routine chest X-ray was performed
for two consecutive days in all the patients and the investigators did not influence its
frequency or timing. Type of surgery, age, gender, preoperative gastric disorders,
size of gas shadow on chest X-ray and presence of nausea and vomiting was
documented. Chest X-rays were interpreted preoperatively, postoperatively with the
endotracheal tube in situ, after extubation of the trachea on day one, and on
postoperative day two. The Chi-squared Fisher’s Exact Test was performed to
determine any significance of a gas shadow in the stomach on PONV. The relative
risk was also calculated.
Results: One patient was ventilated for several days and was excluded from the
study leaving 26 subjects. The average age was 64.64 + 14 and 70 % were male. A
gas shadow was present on preoperative chest X-ray in 15 patients, however, only
one had gastric symptoms (indigestion). After tracheal extubation on postoperative
day one, chests X-rays demonstrated a gas shadow present in 9 of the 26 patients
and 8 of them complained of PONV. Of the remaining 17 patients without gas
shadow only 3 complained of PONV. The relationship between a gas shadow on
chest X-ray and PONV on postoperative day one was therefore very significant (p
value=0.0008) with the relative risk of 4.94 (95% confidence interval 1.76-14.50).
This correlation could not be demonstrated on postoperative day 2.
Conclusion: Presence of a gas shadow on the postoperative chest X-ray after
cardiac surgery has a significant correlation with PONV. This could be due to various
reasons e.g. residual effect of anaesthetic, opioid analgesics, etc. The risk of PONV
is higher in obese or female patients. The prophylactic use of an antiemetic drug or
nasogastric tube to decompress the stomach may therefore be indicated. A
prospective randomised trial is planned to investigate this observation further.
References
1. Pollard BJ, Elliott RA, Moore EW. Eur J Anaesthesiol 2003 Jan;20(1):1-92.
2. Hovorka J, Korttila K, Erkola O. Acta Anaesthesiol Scand 1990 Apr;34(3):203-5
Abstracts submitted to ACTA Cambridge 20 June 2003
5 of 12
Brain Metabolism Following Hypothermic Circulatory Arrest: To Perfuse Or Not Perfuse?
D Harrington, T Clutton-Brock, D Green, P Hutton, JP Lilley, D Riddington, P Townsend, D
Turfrey, M Wilkes, M Faroqui.
Cardiothoracic Unit, Queen Elizabeth Hospital, Birmingham, UK.
Objective.
Hypothermic circulatory arrest (HCA) is associated with a cerebral metabolic deficit
manifest by increased cerebral oxygen extraction as measured by jugular bulb hypoxaemia.
We hypothesised that cold selective antegrade cerebral perfusion (SACP) with moderate
corporeal hypothermia, would attenuate this phenomenon.
Methods.
In a prospective, randomised trial, HCA for arch reconstruction occurred at a nasopharyngeal
temperature of 15ºC. SACP occurred at a nasopharyngeal temperature of 25ºC with a cerebral
perfusate of 15ºC. Paired arterial and jugular venous samples were taken pre and post arrest.
Middle cerebral artery velocity (MCAV) was measured by transcranial Doppler. Analysis
was performed using Mann Whitney U tests.
Results.
There were 22 HCA and 20 SACP patients. There were 3 deaths (7.1%) and 2 strokes (4.8%).
The mean HCA time was 33min (SD 19.4) and the mean SACP + HCA time was 47 min (SD
17.7) (p=0.003). Mean cardiopulmonary bypass times were similar, (221min (63.7) and
203min (41.8) p=0.554). The groups were comparable in terms of pre arrest haematocrit.
From pre to post arrest, jugular bulb pO2 changed by -21.67mmHg (26.4) in the HCA group
versus +2.27mmHg (18.8) in the SACP group (p=0.007). Oxygen extraction changed by
+1.7ml/dl (1.3) in the HCA group versus -1ml/dl (2.4) in the SACP group (p<0.001). MCAV
increased by 6.25cm/s (9.1) in the HCA group and 19.2cm/s (10.1) in the SACP group
(p=0.001).
Conclusion.
This data demonstrates that selective antegrade cerebral perfusion during aortic arch surgery
attenuates the metabolic deficit seen following hypothermic circulatory arrest.
Abstracts submitted to ACTA Cambridge 20 June 2003
6 of 12
Evolving anaesthetic and perfusion techniques for thoraco-abdominal aortic
aneurysm repair
Karim A, Kalkat M, Faroqui M, Lilley J, Townsend P, Green D, Wilkes M, Riddington
D, Turfrey D, Srinivas L, Clutton-Brock T, Jackson P, Bonser RS.
Cardiothoracic Anaesthesia & Surgery, University Hospital Birmingham NHS Trust
Thoraco-abdominal aneurysm(TAAA) repairs have significant risks of mortality and
paraplegia which may be attenuated by some adjunctive techniques. Most outcome
reports are derived from large aortic programmes and there have been few reports of
UK practice.
Between April 1994-March 2002 we undertook 52 primary repairs of TAAAs.
Degenerative 26, chronic dissection 15, Marfan’s dissection 9, acute type B
dissection 1, giant cell arteritis 1. Acute presentation was present in 37/52 (rupture
14, pain 22, bronchus compression 1). We report the progression of our
anaesthetic/perfusion technique and outcomes.
100
90
80
70
60
% 50
40
30
20
10
0
HCA
Cell saver
CSF drain
1994-97
1998-99
2000-01
2002-
Extent
Number
Mortality
Paraplegia
No. Ruptured
Mortality ruptured
Total
52
5 (10%)
1 (2%)
15
3 (20%)
I & II
48
4 (8.3%)
1 (2.2%)
13
2 (15.4%)
III & IV
4
1 (25%)
0
2
1 (50%)
No. non ruptured
Mortality non ruptured
37
2 (6%)
35
2 (6%)
2
0
There has been an evolution of practice to use profound hypothermia, cell salvage
and CSF drainage for complex TAAA repair. Satisfactory outcomes can be achieved
in smaller volume centres with a multi-disciplinary approach to management.
Abstracts submitted to ACTA Cambridge 20 June 2003
7 of 12
Evaluation of a long radial artery catheter for the PiCCO system
R.M.L’E. Orme, D.W. Pigott
Nuffield Department of Anaesthetics, John Radcliffe Hospital, Oxford, UK.
Introduction It has been shown that there is close agreement between cardiac
output as determined by pulmonary artery thermodilution (PACO), aortic
transpulmonary thermodilution (TPCO) and pulse contour analysis (PCCO) [1] using
the PiCCO system (Pulsion Medical Systems, Munich, Germany). The use of a long
radial catheter to measure aortic pressure was described as early as 1974 [2],
prompting the development of a 4Fr 50 cm catheter for the PiCCO system. We have
compared the accuracy of this catheter to a pulmonary artery catheter (TruCCOMs®,
Aortech Critical Care, Bellshill, UK) and investigated whether the use of a shorter
catheter might be possible.
Methods We studied 22 patients undergoing coronary artery surgery.
Measurements were made post-operatively. TPCO was determined using 20ml of
iced injectate. PCCO was then recorded. Simultaneously, PACO was determined
using 10ml of room temperature injectate. After 3 measurements, the catheter was
withdrawn by 5cm and the measurements repeated. Further withdrawals were made
until TPCO was unrecordable. Statistical analysis was by the method of Bland and
Altman. There were no complications related to the radial catheter.
Catheter
Length
50 cm
45 cm
40 cm
35 cm
30 cm
TPCO vs. PACO
Bias (precision) l.min-1
0.38 (0.77)
0.45 (1.18)
0.64 (1.37)
1.03 (1.30)
1.29 (1.56)
PCCO vs. PACO
Bias (precision) l.min-1
0.39 (0.76)
0.41 (1.10)
0.55 (1.34)
0.92 (1.17)
1.23 (1.22)
No. of
Measurements
54
54
51
36
27
Results Data is presented for 18 patients. Bias and precision for PCCO and TPCO
versus PACO are shown in the table. TPCO and thus PCCO could be measured in
all patients after a single 5cm pullback, but could only be recorded in 17 patients at
10 cm pullback, and 9 patients at 20cm pullback.
Conclusions Our results show bias and precision comparable to previous studies
[1]. This catheter may have considerable practical advantages over a femoral
catheter and ensures that central arterial pressure will be used for reliable blood
pressure monitoring. The use of a shorter catheter appears impossible since TPCO
cannot be determined to calibrate the PiCCO system.
References
1. Zollner C, Haller M, Weis M et al. Beat-to-beat measurement of cardiac output
by intravascular pulse contour analysis. J Cardiothorac Vasc Anesth 2000; 14:
125-129
2. Gardner RM, Schwartz RN, Wong HC, Burke JP. Percutaneous indwelling
radial artery catheters for monitoring cardiovascular function. N Engl J Med
1974; 290: 1227-31
Abstracts submitted to ACTA Cambridge 20 June 2003
8 of 12
Metabolic Substrate Support during Coronary Artery Bypass Surgery
The MESSAGE trial
D Quinn & MESSAGE trialists. Queen Elizabeth Hospital, Birmingham
Background
Post-ischaemic myocardial dysfunction following coronary artery bypass grafting
(CABG) may be ameliorated by systemic glucose-insulin-potassium (GIK) therapy.
GIK may favourably alter the balance of intracellular myocardial metabolism during
ischaemia/reperfusion and promote adequate haemodynamic conditions in the early
post-operative period.
Objectives
To determine the effects of GIK therapy on myocardial protection and function in
non-diabetic patients undergoing first-time elective/urgent CABG utilising
cardiopulmonary bypass (CPB), moderate hypothermia and antegrade intermittent
cold blood cardioplegia
Methods
A prospective randomised double-blind placebo-controlled trial of peri-operative
high-dose central intravenous GIK therapy from sternotomy to 6 hours following
release of the aortic cross clamp was conducted in 280 patients (GIK n=139,
dextrose 5% n= 141) using standardised protocols for anaesthesia, surgery, CPB,
myocardial protection, blood glucose management and inotropic and vasoconstrictor
support. Haemodynamic function was monitored using sequential pulmonary artery
flotation balloon catheter measurements. Serial sampling of blood glucose,
potassium and cardiac troponin I was performed from baseline in all patients. Low
cardiac output state (LCOS) incidence was assessed by an independent committee.
A standard battery of neuropsychometric tests were administered at baseline, 5-7
days and 8 weeks after surgery in 68 patients. Statistical analysis was performed
using repeated measures for sequential data and 2 analysis of dichotomous
variables.
Results
Groups were comparable for all pre- and intra-operative variables. There were 5
deaths (GIK n=3) and no difference in treated infection episodes (GIK 27%, control
22%), post-operative focal neurological (GIK 1.4%, control 3.6%) or
neuropsychometric deficit (at 5 days and 8 weeks), post reperfusion ventricular (GIK
14.3%, control 12.9%) and atrial fibrillation (GIK 53.6, control 46%). GIK patients had
higher blood glucose levels (p=0.003) and required more exogenous insulin. GIK
resulted in a higher cardiac index (p<0.0001) and a lower systemic vascular
resistance index (p<0.0001) over the first 12 hours post ischaemia. GIK recipients
were less likely to experience a LCOS (GIK 16.5%, control 26.9%) or inotropic
support (GIK 26.1%, control 43.1% p < 0.0001) However during this period the
requirements for noradrenaline were greater for these patients (GIK 69%, control
45.1%). Troponin I release over the first 12 hours was lower in GIK recipients (p =
0.03).
Conclusion
GIK therapy increases cardiac output and reduces vascular resistance. This
translates into a reduced incidence of LCOS and inotrope requirement. Lower
troponin release suggests enhanced myocardial protection. Important side effects
were not increased in the GIK group.
Abstracts submitted to ACTA Cambridge 20 June 2003
9 of 12
A study of the variation in beta hydroxybutyrate concentrations in perioperative
diabetic cardiac surgical patients
A Relwani, GR McAnulty, S Stacey, A Crerar-Gilbert
Anaesthetic Department, St George's Hospital, London, UK
Introduction: Conventional perioperative diabetic management maintains blood glucose
concentrations within a desired range. Normalisation of blood –hydroxybutyrate may be
beneficial in diabetic ketoacidosis[1].We measured perioperative changes in hydroxybutyrate (-OHB) concentrations in type 1 and 2 diabetic cardiac surgical
patients to assess its potential as an additional monitor for adequacy of metabolic
control.
Materials and methods: This was a pilot observational study approved by the local
Ethics Committee. Patients gave written consent. All patients underwent coronary artery
bypass grafting. -OHB concentrations were measured using MediSense® Optium™ 
ketone electrodes and sensor (Abbott Laboratories). 10 bedside measurements of OHB were made for each patient: 6 at hourly intervals were taken from the time of
induction of anaesthesia followed by 4 at 6 hourly intervals. Prescribed treatment was 20
ml/hr 50% glucose and variable rate of soluble human insulin (intravenous infusions) to
maintain blood glucose between 4.7-6.4 mmol/l from midnight before the surgery till the
re-establishment of pre-operative therapy. This was not achieved at all times.
Results: 17 patients were studied, 4 females, 13 males, aged 51 to 81years (mean 64).
9 patients were type 2 and 8 type 1 diabetics. Type 2 diabetics were treated with
gliclazide(3), metformin(3), metformin and glibenclamide(1) and metformin with
insulin(1). Mean blood glucose during the study period was 6.75  0.49 mmol/l (range
4.1-20.6). -OHB was detected in 10 patients (4 type 1, 6 type 2). Concentrations were
low in most patients and ranged between 0.1 - 0.3 mmol/l (normal < 0.5 mmol/l). In 2
patients, (one type 1, one type 2) peak -OHB concentrations were 1.3 and 1.7 mmol/l.
These high -OHB levels occurred when prescribed insulin infusions had been
interrupted and decreased once insulin treatment was re-started (figure 1). -OHB
concentrations did not correlate with blood glucose concentrations. (Spearman r =
0.2569, p = 0.0008).
Summary and conclusions: -OHB concentrations may be elevated in the presence of
relatively normal blood glucose in both type 1 and type 2 diabetics following cardiac
surgery. -OHB may be a more sensitive indicator of metabolic derangement than
glucose concentrations alone. Further studies are needed to determine clinical
application.
TIME (hours post induction)
PATIENT 1
(Type 1 DM)
0
1
2
3
4
5
6
12
18
24
BLOOD GLUCOSE (mmol l-1)
6.6
10.6
11.9
14.3
13.8
8.7
4.1
11.2
7.4
8.3
b-OHB (mmol l-1)
0.9
1.1
1.3
0.2
0
0
0
0
0
0
0
0
5
8
10
10
5
5
1
1
BLOOD GLUCOSE (mol l-1)
7.5
9.7
11
11
11.5
12.9
7.9
7.4
11.7
10.8
b-OHB (mol l-1)
0.5
0.2
0.2
0.3
0
0
0
0.1
0
1.7
1
3
6
6
6
6
3
3
6
0
INSULIN DOSE (last hour, International Units)
PATIENT 2
(Type 2 DM)
INSULIN DOSE (last hour, International Units)
References:
1.Wiggam MI, et al. Treatment of diabetic ketoacidosis using normalization of blood 3hydroxybutyrate concentration as an endpoint of emergency management. Diabetes
Care 1997; 20:1347-52.
Abstracts submitted to ACTA Cambridge 20 June 2003
10 of 12
Differential temperature management during cardiopulmonary bypass surgery
to achieve cerebral hypothermia and corporeal normothermia in humans
Authors: Srinivas LV, Kaukuntla H, Townsend P, Green DH, Riddington DR, Bonser
RS & Study Group
Cardiothoracic Surgical Unit, Queen Elizabeth Hospital, Birmingham, United
Kingdom.
Objectives
Normothermic cardiopulmonary bypass (CPB) has become popular over the last
decade as it has been shown to have various benefits although at a potentially
increased risk of neurological injury compared to hypothermic CPB. A new technique
which utilises a dual lumen aortic cannula (Cobra catheter, Cardeon Corp,
Cupertino, USA) to segment the aortic arch and achieve cerebral cooling in
association with body normothermia has been described. The aim of our study was
to investigate the thermal efficacy of this technique to achieve and maintain a
temperature differential of greater than 5º C between the brain and the body during
CPB
Methodology
After ethical approval, 30 adult patients underwent CPB using the Cardeon Cobra
cannula to differentially cool the brain while maintaining body normothermia.
Nasopharyngeal (NPT) and bladder temperatures (BLT) were used as surrogates of
brain and body temperatures. Brain (radial) and corporeal (femoral) mean arterial
pressure (MAP) together with jugular bulb and mixed venous saturations were
monitored to assess perfusion adequacy to cerebral and corporeal circulations.
Results
The catheter was successfully placed in all patients without any difficulty. The
procedures performed were coronary artery bypass surgery (n=23), valve (n=2) and
combined valve & graft (n=5). A 3.2±0.46oC differential between BLT and NPT was
reached in all patients after 5.5±3.6 minutes (p<0.001). A 5oC differential was
reached in 29 patients after 12±7.5 minutes. The mean difference was 6.6±1 oC.
Mean arterial pressures were maintained above 50mmHg and venous saturations
above 60% throughout.
Conclusions
Differential temperature management using the new aortic cannula is possible.
Cerebral hypothermia can be achieved while maintaining corporeal normothermia
with adequate perfusion to both circulations reliably. This could potentially give the
benefits of hypothermic and normothermic CPB.
Abstracts submitted to ACTA Cambridge 20 June 2003
11 of 12
Mannitol in the bypass prime does not modify renal tubular function
Yallop K, Twyman S1, Tang A, Smith D
Wessex Cardiothoracic Centre, and 1Dept of Biochemistry, Southampton General
Hospital, Southampton, England
Introduction: Renal dysfunction occurs in 2-5% of adult patients following
cardiopulmonary bypass (CPB), causing significant morbidity and mortality of 1020% [1]. Mannitol is often added to the CPB prime to reduce renal damage, but
previous studies using mannitol have produced conflicting results.
Method: In a double blind, randomised, controlled trial in 40 cardiac surgical patients
with normal renal function, 20 patients had 5ml kg-1 of 10% mannitol in the CPB
prime, while 20 had an equivalent volume of Hartmann’s solution. Standard CPB
prime was with Hartmann’s solution 1000ml, gelofusine 500ml and 5000 iu heparin.
Blood and urine samples were taken on admission (baseline), on arrival in the ITU
and for 5 postoperative days for measurement of plasma urea and creatinine, urinary
creatinine, microalbumin and retinol binding protein (RBP) [2]. Urinary microalbumin
and RBP were indexed to urine creatinine, to indicate renal glomerular and tubular
damage respectively. Data were analysed using area under the curve methodology
and Mann-Whitney U testing in SPSS for Windows.
Results: The two groups were similar in terms of pre-operative variables. The study
had a power of 0.97 to detect a 10% difference in RBP between groups. There were
no significant differences between mannitol and control patients for urine output, fluid
balance, plasma creatinine or urea, or urinary microalbumin or RBP indexed to
creatinine.
- pre-op
5
Log RBP/creat
- day0
4
Log RBP/creat
- day1
3
Log RBP/creat
- day2
Log RBP/creat
2
- day3
Log RBP/creat
1
- day4
Log RBP/creat
- day5
0
mannitol
control
Figure: Log10 urinary RBP:creatinine index from baseline to post-operative
day five in the two study groups. Values increased significantly between
admission and arrival on ITU, then returned slowly to normal.
Discussion: Mannitol has little impact on indices of renal function in patients with
normal pre-operative plasma creatinine, and its routine use should therefore be
reconsidered.
References:
1 Conlon PJ, Stafford-Smith M, White WD, et al. Acute renal failure following
cardiac surgery. Nephrol Dial Transplant 1999; 14: 1158-1162.
2 Twyman SJ, Overton J, Rowe DJ. Measurement of urinary retinol binding protein
by immunonephelometry. Clin Chim Acta 2000; 297: 155-61.
Abstracts submitted to ACTA Cambridge 20 June 2003
12 of 12
Impact of new transfusion guidelines on reduction of blood product use in
cardiac surgery
B Yim, R Parker, D Pigott
Oxford Heart Center, John Radcliffe Hospital
Background:
According to the 2001 national benchmarking audit of blood and component use in
primary myocardial revascularisation [1], the rate of blood product usage at our
cardiac unit was far above the national average. During this period, blood products
were prescribed as per clinical impression of the treating anaesthetist or surgeon. A
new transfusion protocol was therefore implemented to rationalize the use of blood
products in our unit. In particular, in line with current research and practice [2], we
have introduced haemoglobin of less than 7.0g/dL as a trigger for red cells
transfusion.
Methods:
A new transfusion protocol was introduced in our cardiac unit on the 1 st December
2002. Red cells were only transfused if hemoglobin fell to <7g/dl. Coagulation factors
were only indicated in bleeding patients with abnormal findings as per standard
coagulation tests and thromboelastogram findings.
After introduction of the new protocol, 170 patients were followed up prospectively
with respect to blood product usage. The results were then compared with the group
of patients used for the national benchmark audit.
Results:
Pre
protocol
Post
protocol
Red cell use
% Patient Mean no
transfused units
used
75%
3.3
FFP use
% Patient
transfused
51%
2.1
33
Mean no
units
used
1.4
Platelets use
% Patient Mean no
transfused units
used
31%
0.5
12%
0.6
21%
0.4
Discussion:
Since the introduction of our new transfusion protocol, we have significantly reduced
the use of blood products in our unit. This represents a potential reduction in risk
inherently associated with blood transfusion and a significant cost savings to our
unit.
References
[1]National Benchmarking Audit of Blood and Component use in Primary Myocardial
Revascularisation
[2]Herbert PC, Yetisir E, Martin C, Blajchman MA, Wells, G, Marshall J, Tweeddale
M, Pagliarello G, Schweitzer I: Is a low transfusion threshold safe in critically ill
patients with cardiovascular diseases. Crit Care Med 2001 Vol. 29, No 2, pp227-34