M . Szpytma et al .: J Extra Corpor Technol 2024 , 56 , 149 – 158 155
Table 7 . Subgroup analysis : Intraoperative variables for aortic cross-clamp time greater than 120 min .
Variable |
HKB |
DNC |
p-value |
N |
64 |
64 |
|
Procedure type CABG |
5 ( 8 %) |
3 ( 5 %) |
0.77 |
Aortic / Dissection |
5 ( 8 %) |
9 ( 14 %) |
|
Other |
6 ( 9 %) |
5 ( 8 %) |
|
Valve |
33 ( 52 %) |
31 ( 48 %) |
|
Valve / CABG |
15 ( 23 %) |
16 ( 25 %) |
|
CPB time ( min ) |
185 ( 160 , 210 ) |
190 ( 166 , 217 ) |
0.69 |
AXC time ( min ) |
146 ( 129 , 165 ) |
143 ( 130 , 173 ) |
0.98 |
Total procedure time ( min ) |
294 ( 248 , 332 ) |
322 ( 271 , 375 ) |
0.015 |
Hemofiltration requirement |
0 ( 0 %) |
4 ( 6 %) |
0.12 |
Fluid output ( mL ) |
400 ( 200 , 750 ) |
460 ( 250 , 1188 ) |
0.35 |
Minimum haemoglobin ( g / L ) |
91 ( 77 , 103 ) |
91 ( 76 , 101 ) |
0.75 |
Minimum cardioplegia temperature (° C ) |
31 ( 30 , 31 ) |
5 ( 5 , 6 ) |
< 0.001 |
Total cardioplegia volume delivered ( mL ) |
2129 ( 1950 , 2486 ) |
1523 ( 1007 , 2009 ) |
< 0.001 |
Cardioplegia delivery route Antegrade |
30 ( 47 %) |
43 ( 67 %) |
0.031 |
Retrograde |
0 ( 0 %) |
1 ( 2 %) |
|
Antegrade + Retrograde |
34 ( 53 %) |
20 ( 31 %) |
|
Number of cardioplegia doses |
7 ( 6 , 8 ) |
2 ( 1 , 4 ) |
< 0.001 |
Spontaneous recovery of rhythm |
36 ( 56 %) |
56 ( 89 %) |
< 0.001 |
Maximum ischemic time ( min ) |
32 ( 29 , 39 ) |
101 ( 87 , 119 ) |
< 0.001 |
Peak creatinine on pump ( umol / L ) |
101 ( 76 , 135 ) |
103 ( 83 , 165 ) |
0.22 |
Last haemoglobin on pump ( g / L ) |
93 ( 80 , 104 ) |
94 ( 86 , 105 ) |
0.36 |
Continuous variables are expressed median ( IQR ), categorical variables are expressed number (%). Abbreviation : Abbreviation : HKB – hyperkalaemic blood cardioplegia ; DNC – Del Nido cardioplegia ; CABG – coronary artery bypass graft ; CPB – cardiopulmonary bypass ; AXC – aortic cross-clamp .
Table 8 . Subgroup analysis : Postoperative variables for aortic crossclamp time greater than 120 min .
Characteristic |
HKB |
DNC |
p-value |
N |
64 |
64 |
|
Mechanical ventilation ( h ) |
20 ( 12 , 42 ) |
20 ( 16 , 68 ) |
0.40 |
ICU stay ( h ) |
92 ( 45 , 142 ) |
90 ( 46 , 186 ) |
0.72 |
Hospital stay ( day ) |
10 ( 7 , 14 ) |
10 ( 7 , 15 ) |
0.49 |
Mortality within 30 days |
2 ( 3 %) |
4 ( 6 %) |
0.68 |
In hospital mortality |
2 ( 3 %) |
4 ( 6 %) |
0.68 |
Return to theatre |
1 ( 2 %) |
6 ( 10 %) |
0.049 |
Stroke |
1 ( 2 %) |
2 ( 3 %) |
0.62 |
AKI |
11 ( 17 %) |
16 ( 25 %) |
0.28 |
PRBC |
26 ( 41 %) |
29 ( 47 %) |
0.49 |
MI |
6 ( 9 %) |
11 ( 17 %) |
0.20 |
IABP |
8 ( 13 %) |
4 ( 6 %) |
0.36 |
Continuous variables are expressed median ( IQR ), categorical variables are expressed number (%). Abbreviations : HKB – hyperkalemic blood cardioplegia ; DNC – Del Nido cardioplegia ; ICCU – Intensive Critical Care Unit ; AKI – acute kidney injury ; PRBC – Any red blood cell transfusion ; MI – myocardial infarction ; IABP – intra-aortic balloon pump .
retrograde delivery in 64 % of patients . This variation likely reflects the patient population chosen ( those with prolonged cross-clamp times ) and the delivery strategy for multiple dose HKB frequently utilising a combined antegrade and retrograde delivery strategy in these patients . The significance of the mode of re-delivery is unclear and given the high variability in existing literature , highlights the need for randomized controlled trials and standardized guidelines given variable clinical implementation . Expectedly the number of cardioplegia doses was 6 ( HKB ) compared to 1 ( DNC ) in the primary analysis and 7 ( HKB ) versus 2 ( DNC ) in the sensitivity analysis . The maximum ischaemic time was 32 and 98 min in the HKB and DNC groups reflecting our institutions redosing at approximately 30 and 90 min respectively .
The higher rate of return of spontaneous rhythm and lower need for defibrillation on removal of AXC in DNC is well reported [ 4 , 6 , 27 – 29 ]. Our results showed the DNC cohort wasmorelikelytoreturntospontaneousrhythmwithmultidose DNC regiments consistent in primary and sub-analyses ( Tables 3 and 7 ) and is consistent with findings our previously published experience [ 17 ].
Quality improvement
There is no clear dosing regimen for extended cross-clamp time and DNC use . Current protocols are based on experience , vary widely and make inter study comparisons challenging . The dosing regimens in the literature range from an initial dose of DNC of 1000 – 1200 mL with an additional maintenance dose of 300 – 1000 mL every 60 min after 90 min of cross-clamp time [ 4 – 7 , 9 – 11 , 17 ].
Following our initial evaluation of DNC use , adjustments to practice were made and commonly a DNC dosing protocol with initiation with 1000 mL DNC induction dose followed by a