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Original Article This article is accompanied by an invited commentary by Dr. K. Muralidhar
Modified Blalock Taussig shunt: Comparison between neonates, infants and older children Sarvesh Pal Singh, Sandeep Chauhan, Minati Choudhury, Vishwas Malik, Sachin Talwar1, Milind P. Hote1, Velayoudham Devagourou1 Departments of Cardiac Anesthesia and 1Cardio-Thoracic and Vascular Surgery, Cardio-Thoracic Sciences Center, All India Institute of Medical Sciences, New Delhi, India
ABSTRACT
Received: 14-12-13 Accepted: 26-04-14
Objective: The aim was to compare various pre-and post-operative parameters and to identify the predictors of mortality in neonates, infants, and older children undergoing Modified Blalock Taussig shunt (MBTS). Materials and Methods: Medical records of 134 children who underwent MBTS over a period of 2 years through thoracotomy were reviewed. Children were divided into three groups-neonates, infants, and older children. For analysis, various pre-and post-operative variables were recorded, including complications and mortality. Results: The increase in PaO2 and SaO2 levels after surgery was similar and statistically significant in all the three groups. The requirement of adrenaline, duration of ventilation and mortality was significantly higher in neonates. The overall mortality and infant mortality was 4.5% and 8%, respectively. Conclusion: Neonates are at increased risk of complications and mortality compared with older children. Age (24 h and post shunt increase in PaO2 (PDiff) 80% and if required, O2 concentration was increased to 100% to achieve the same. If the SpO2 remained below 80% even after an increase of O2 to 100%, the lower SpO2 was accepted. The branch PA and SCA were dissected prior to the placement of a partial occlusive clamp on them. Before partially clamping the SCA, heparin 100 U/kg was administered to achieve an activated coagulation time (ACT) of about 200s. A Gore-Tex polytetrafluoroethylene (PTFE) graft (W L Gore and Associates, Inc., AZ, USA) was used as a conduit between SCA and branch PA. The size of PTFE graft was selected on the basis of body weight, 3.0 mm for preterm neonate or weight 6 kg child. Intraoperatively, children 192
with a preoperative hematocrit (Hct) >45% underwent either hemodilution or autologous blood withdrawal or both to maintain Hct around 45%. If the Hct was 3 consecutive hours or >10% of estimated blood volume at least for 1 h was taken as a criterion for mediastinal exploration. Shunt thrombosis in any child was an indication for reoperation. For analysis, following variables were collected, shunt size, emergency MBTS, previous MBTS, preoperative PaO2 (P1) and SaO2 (S1) after intubation and starting of mechanical ventilation. Any MBTS done after the completion of elective operative list and before the start of the next day’s operative list was termed as emergency surgery. Patients receiving mechanical ventilation for >24 h before surgery were grouped as preoperative mechanically ventilated patients. The following postoperative variables were collected: Inotropes and their duration; hemoglobin (Hb), SaO2 (S2), PaO2 (P2) on arrival in ICU; duration of mechanical ventilation and ICU stay; incidence of exploration, revision of the primary procedure, reintubation, and complications, including mortality. P2 and S2 values were the values taken on arrival in the ICU when the patient was ventilated with FiO2 of 60%. The difference between P2-P1 (P Diff) and S2-S1 (SDiff) was calculated for each patient. Patients were divided into three groups-neonates (1 year age for comparison. Annals of Cardiac Anaesthesia z Vol. 17:3 z Jul-Sep-2014
[Downloaded free from http://www.annals.in on Saturday, July 05, 2014, IP: 202.177.173.189] || Click here to download free Android application for this journal Singh, et al.: Modified Blalock Taussig shunt
Statistics Data were analyzed using SPSS 20 (SPSS, Inc., Chicago, IL, USA). Age, weight and shunt size were expressed as median (range). String variables such as gender, side of shunt, emergency surgery, previous MBTS, prostaglandin infusion, reintubation, mediastinal exploration were expressed as a proportion. Complications and mortality were shown as a percentage. All other variables were mentioned as mean ± standard deviation. Nominal data with Gaussian distribution was compared using Analysis of Variance and non-Gaussian parameters with Kruskal-Wallis test. Chi-square test was used to compare categorical variables. P24 h before the surgery. The mean preoperative PaO2 and SaO2 were 39.54 ± 6.29 mmHg and 69.21 ± 7.67%, respectively. Of 134 children, 125 received inotropes of which dopamine was the most preferred inotrope and was used in all the children. Adrenaline was used as a second inotrope in 16 children and noradrenaline in three children. Thirty six children had packed red blood cell (pRBC) transfusion with a mean amount of 3.31 ± 6.79 ml/kg. The mean Hb, PaO2 and SpO2 post MBTS were 16.24 ± 2.84 g/dl, 54.83 ± 9.74 mmHg and 84.29% ±7.68%, respectively. The mean duration of mechanical ventilation and ICU stay were 16.22 ± 23.97 and 48.72 ± 57.01 h. Out of 134 children, 8 (5.97%) Table 1: Different diagnoses for which MBTS were done Diagnosis
Number of patients
Tetralogy of Fallot with PS or PA
61
Double outlet right ventricle with VSD and PS/PA
22
Tricuspid atresia with VSD and PA/PS
18
VSD with PA
13
D transposition of great arteries with VSD and PS/PA
12
CC transposition of great arteries with VSD and PA
3
Complete atrioventricular septal defect with PS
3
Double outlet right ventricle with VSD with PS and atrioventricular discordance
1
Double outlet left ventricle with VSD and hypoplastic MPA and right ventricle
1
VSD: Ventricular septal defect, PA: Pulmonary atresia, PS: Pulmonary stenosis, MPA: Main pulmonary artery, D: Dextro, CC: Congenitally corrected, MBTS: Modified Blalock Taussig shunt
Annals of Cardiac Anaesthesia z Vol. 17:3 z Jul-Sep-2014
underwent tracheal reintubation, 13 (9.7%) underwent mediastinal exploration and 3 (2.2%) revision of the primary procedure. The various complications are summarized in Table 2. Excessive postoperative bleeding (12.68%) was the most common complication followed by low cardiac output. Overall mortality of 4.47% (6/134) was observed. Table 2 compares different variables among the three groups of neonates, infants and older children. There was a significant increase in the size of PTFE graft with age (3 mm vs. 4 mm vs. 5 mm). Requirement of adrenaline as an inotrope was maximum in neonates (100%) followed by infants and children. This difference was statistically significant (P < 0.001). The duration for dopamine infusion was significantly higher in neonates compared with the rest of the groups (P = 0.004). The Hb levels were significantly different among the groups with neonates having lowest and children the highest levels (14.38 ± 3.04 vs. 15.80 ± 2.77 vs. 16.98 ± 2.73, P = 0.01). Within the group comparison showed that the PaO2 and SaO2 levels significantly increased (P2 > P1 and S2 > S1) in all the three groups after MBTS surgery (P < 0.001 for both the variables in all the groups). However, on comparing the mean PDiff and SDiff values among the various groups, no statistically significant difference was found. The increase in PaO2 and SaO2 was similar in all the groups. Compared to infants and older children the duration of mechanical ventilation was significantly higher in neonates (P = 0.009; P = 0.005, respectively). Compared to the other groups mortality was significantly higher in the neonatal group (P = 0.004). Excessive postoperative bleeding was the most common complication in children (10/59) and infants (6/67). Three infants underwent shunt revision, two for shunt thrombosis and one for upsizing the shunt graft. None of the shunts were clipped. Lung collapse occurred in one infant and low cardiac output (? Sepsis) developed in another one and both underwent early tracheostomy. Univariate analysis showed that increasing age, weight, shunt size and PDiff lead to increased survival whereas increases in adrenaline usage, amount of blood transfusion, duration of mechanical ventilation, tracheal reintubation and revision of the primary procedure were associated with decreased survival. Multivariate analysis using stepwise logistic regression identified age 24 h and increase in PaO2 of 1 year) Variable
Neonate (n=8)
Infant (n=67)
Older children (n=59)
Age (days): Median (range)
13 (3-24)
290 (45-335)
730 (365-3650)
Weight (kg): Median (range)
2.65 (2-3)
5.4 (2.5-8.5)
10 (4.8-20)
Shunt size (mm): Median (range)
3.5 (3-3.5)
4 (3.5-5)*
5 (4-5)*
Emergency shunts (n)
3
18
16
Previous MBTS (n)
0
1
3
Inotropes Dopamine (n)
8
64
53
Adrenaline (n)
8*
5
3
Noradrenaline (n)
0
0
3
Dopamine (h)
70.62±79.33*
31.03±31.71
27.76±19.22
Adrenaline (h)
64.12±76.83
19.16±7.38
58.66±41.05
0
0
52.33±46.19
PaO2, before MBTS, P1 (mmHg)
39.87±7.41
39.50±6.78
39.46±5.60
SaO2 before MBTS, S1 (%)
68.62±9.48
68.8±8.21
69.67±6.85
PaO2, after MBTS, P2 (mmHg)
54.00±13.6^
54.55±9.85^
55.27±9.18^
SaO2 after MBTS, S2 (%)
85.75±8.24^
84.26±7.89^
84.13±7.48^
PDiff (P2-P1), (mmHg)
14.12±12.34
15.11±5.90
15.98±6.65
SDiff (S2-S1), (%)
17.12±6.44
15.38±5.04
14.45±5.09
Hemoglobin on arrival in the ICU (g/dl)
14.38±3.04*
15.80±2.77
16.08±2.73
Inotropes duration
Noradrenaline (h)
PRBC transfusion (n) Amount in (ml/kg) Duration of mechanical ventilation (h)
3
20
14
6.25±9.89
3.66±6.87
2.52±6.18 12.94±18.98
51.75±64.13*
14.86±15.51*
Number of patients reintubated (n)
1
4
3
Mechanical ventilation after reintubation (h)
10
19.25±8.77
10.33±7.76
No of patients explored for excessive postoperative bleeding (n)
1
3
9
Number of patients who underwent revision of the primary procedure (n)
0
3
0
Complications (n)
3
14
12
Excessive bleeding
1
6
10
Low cardiac output
0
3
0
Lung collapse
0
1
1
Shunt thrombosis
0
2
0
Acute pulmonary edema
1
0
0
Contralateral pneumothorax
1
0
0
Acute renal failure
0
0
1
Tracheostomy
0
2
0
80.25±86.74
50.68±67.49
41.23±34.10
2*
4
0
ICU stay, h (mean±SD) Mortality (n)
*P
Original Article This article is accompanied by an invited commentary by Dr. K. Muralidhar
Modified Blalock Taussig shunt: Comparison between neonates, infants and older children Sarvesh Pal Singh, Sandeep Chauhan, Minati Choudhury, Vishwas Malik, Sachin Talwar1, Milind P. Hote1, Velayoudham Devagourou1 Departments of Cardiac Anesthesia and 1Cardio-Thoracic and Vascular Surgery, Cardio-Thoracic Sciences Center, All India Institute of Medical Sciences, New Delhi, India
ABSTRACT
Received: 14-12-13 Accepted: 26-04-14
Objective: The aim was to compare various pre-and post-operative parameters and to identify the predictors of mortality in neonates, infants, and older children undergoing Modified Blalock Taussig shunt (MBTS). Materials and Methods: Medical records of 134 children who underwent MBTS over a period of 2 years through thoracotomy were reviewed. Children were divided into three groups-neonates, infants, and older children. For analysis, various pre-and post-operative variables were recorded, including complications and mortality. Results: The increase in PaO2 and SaO2 levels after surgery was similar and statistically significant in all the three groups. The requirement of adrenaline, duration of ventilation and mortality was significantly higher in neonates. The overall mortality and infant mortality was 4.5% and 8%, respectively. Conclusion: Neonates are at increased risk of complications and mortality compared with older children. Age (24 h and post shunt increase in PaO2 (PDiff) 80% and if required, O2 concentration was increased to 100% to achieve the same. If the SpO2 remained below 80% even after an increase of O2 to 100%, the lower SpO2 was accepted. The branch PA and SCA were dissected prior to the placement of a partial occlusive clamp on them. Before partially clamping the SCA, heparin 100 U/kg was administered to achieve an activated coagulation time (ACT) of about 200s. A Gore-Tex polytetrafluoroethylene (PTFE) graft (W L Gore and Associates, Inc., AZ, USA) was used as a conduit between SCA and branch PA. The size of PTFE graft was selected on the basis of body weight, 3.0 mm for preterm neonate or weight 6 kg child. Intraoperatively, children 192
with a preoperative hematocrit (Hct) >45% underwent either hemodilution or autologous blood withdrawal or both to maintain Hct around 45%. If the Hct was 3 consecutive hours or >10% of estimated blood volume at least for 1 h was taken as a criterion for mediastinal exploration. Shunt thrombosis in any child was an indication for reoperation. For analysis, following variables were collected, shunt size, emergency MBTS, previous MBTS, preoperative PaO2 (P1) and SaO2 (S1) after intubation and starting of mechanical ventilation. Any MBTS done after the completion of elective operative list and before the start of the next day’s operative list was termed as emergency surgery. Patients receiving mechanical ventilation for >24 h before surgery were grouped as preoperative mechanically ventilated patients. The following postoperative variables were collected: Inotropes and their duration; hemoglobin (Hb), SaO2 (S2), PaO2 (P2) on arrival in ICU; duration of mechanical ventilation and ICU stay; incidence of exploration, revision of the primary procedure, reintubation, and complications, including mortality. P2 and S2 values were the values taken on arrival in the ICU when the patient was ventilated with FiO2 of 60%. The difference between P2-P1 (P Diff) and S2-S1 (SDiff) was calculated for each patient. Patients were divided into three groups-neonates (1 year age for comparison. Annals of Cardiac Anaesthesia z Vol. 17:3 z Jul-Sep-2014
[Downloaded free from http://www.annals.in on Saturday, July 05, 2014, IP: 202.177.173.189] || Click here to download free Android application for this journal Singh, et al.: Modified Blalock Taussig shunt
Statistics Data were analyzed using SPSS 20 (SPSS, Inc., Chicago, IL, USA). Age, weight and shunt size were expressed as median (range). String variables such as gender, side of shunt, emergency surgery, previous MBTS, prostaglandin infusion, reintubation, mediastinal exploration were expressed as a proportion. Complications and mortality were shown as a percentage. All other variables were mentioned as mean ± standard deviation. Nominal data with Gaussian distribution was compared using Analysis of Variance and non-Gaussian parameters with Kruskal-Wallis test. Chi-square test was used to compare categorical variables. P24 h before the surgery. The mean preoperative PaO2 and SaO2 were 39.54 ± 6.29 mmHg and 69.21 ± 7.67%, respectively. Of 134 children, 125 received inotropes of which dopamine was the most preferred inotrope and was used in all the children. Adrenaline was used as a second inotrope in 16 children and noradrenaline in three children. Thirty six children had packed red blood cell (pRBC) transfusion with a mean amount of 3.31 ± 6.79 ml/kg. The mean Hb, PaO2 and SpO2 post MBTS were 16.24 ± 2.84 g/dl, 54.83 ± 9.74 mmHg and 84.29% ±7.68%, respectively. The mean duration of mechanical ventilation and ICU stay were 16.22 ± 23.97 and 48.72 ± 57.01 h. Out of 134 children, 8 (5.97%) Table 1: Different diagnoses for which MBTS were done Diagnosis
Number of patients
Tetralogy of Fallot with PS or PA
61
Double outlet right ventricle with VSD and PS/PA
22
Tricuspid atresia with VSD and PA/PS
18
VSD with PA
13
D transposition of great arteries with VSD and PS/PA
12
CC transposition of great arteries with VSD and PA
3
Complete atrioventricular septal defect with PS
3
Double outlet right ventricle with VSD with PS and atrioventricular discordance
1
Double outlet left ventricle with VSD and hypoplastic MPA and right ventricle
1
VSD: Ventricular septal defect, PA: Pulmonary atresia, PS: Pulmonary stenosis, MPA: Main pulmonary artery, D: Dextro, CC: Congenitally corrected, MBTS: Modified Blalock Taussig shunt
Annals of Cardiac Anaesthesia z Vol. 17:3 z Jul-Sep-2014
underwent tracheal reintubation, 13 (9.7%) underwent mediastinal exploration and 3 (2.2%) revision of the primary procedure. The various complications are summarized in Table 2. Excessive postoperative bleeding (12.68%) was the most common complication followed by low cardiac output. Overall mortality of 4.47% (6/134) was observed. Table 2 compares different variables among the three groups of neonates, infants and older children. There was a significant increase in the size of PTFE graft with age (3 mm vs. 4 mm vs. 5 mm). Requirement of adrenaline as an inotrope was maximum in neonates (100%) followed by infants and children. This difference was statistically significant (P < 0.001). The duration for dopamine infusion was significantly higher in neonates compared with the rest of the groups (P = 0.004). The Hb levels were significantly different among the groups with neonates having lowest and children the highest levels (14.38 ± 3.04 vs. 15.80 ± 2.77 vs. 16.98 ± 2.73, P = 0.01). Within the group comparison showed that the PaO2 and SaO2 levels significantly increased (P2 > P1 and S2 > S1) in all the three groups after MBTS surgery (P < 0.001 for both the variables in all the groups). However, on comparing the mean PDiff and SDiff values among the various groups, no statistically significant difference was found. The increase in PaO2 and SaO2 was similar in all the groups. Compared to infants and older children the duration of mechanical ventilation was significantly higher in neonates (P = 0.009; P = 0.005, respectively). Compared to the other groups mortality was significantly higher in the neonatal group (P = 0.004). Excessive postoperative bleeding was the most common complication in children (10/59) and infants (6/67). Three infants underwent shunt revision, two for shunt thrombosis and one for upsizing the shunt graft. None of the shunts were clipped. Lung collapse occurred in one infant and low cardiac output (? Sepsis) developed in another one and both underwent early tracheostomy. Univariate analysis showed that increasing age, weight, shunt size and PDiff lead to increased survival whereas increases in adrenaline usage, amount of blood transfusion, duration of mechanical ventilation, tracheal reintubation and revision of the primary procedure were associated with decreased survival. Multivariate analysis using stepwise logistic regression identified age 24 h and increase in PaO2 of 1 year) Variable
Neonate (n=8)
Infant (n=67)
Older children (n=59)
Age (days): Median (range)
13 (3-24)
290 (45-335)
730 (365-3650)
Weight (kg): Median (range)
2.65 (2-3)
5.4 (2.5-8.5)
10 (4.8-20)
Shunt size (mm): Median (range)
3.5 (3-3.5)
4 (3.5-5)*
5 (4-5)*
Emergency shunts (n)
3
18
16
Previous MBTS (n)
0
1
3
Inotropes Dopamine (n)
8
64
53
Adrenaline (n)
8*
5
3
Noradrenaline (n)
0
0
3
Dopamine (h)
70.62±79.33*
31.03±31.71
27.76±19.22
Adrenaline (h)
64.12±76.83
19.16±7.38
58.66±41.05
0
0
52.33±46.19
PaO2, before MBTS, P1 (mmHg)
39.87±7.41
39.50±6.78
39.46±5.60
SaO2 before MBTS, S1 (%)
68.62±9.48
68.8±8.21
69.67±6.85
PaO2, after MBTS, P2 (mmHg)
54.00±13.6^
54.55±9.85^
55.27±9.18^
SaO2 after MBTS, S2 (%)
85.75±8.24^
84.26±7.89^
84.13±7.48^
PDiff (P2-P1), (mmHg)
14.12±12.34
15.11±5.90
15.98±6.65
SDiff (S2-S1), (%)
17.12±6.44
15.38±5.04
14.45±5.09
Hemoglobin on arrival in the ICU (g/dl)
14.38±3.04*
15.80±2.77
16.08±2.73
Inotropes duration
Noradrenaline (h)
PRBC transfusion (n) Amount in (ml/kg) Duration of mechanical ventilation (h)
3
20
14
6.25±9.89
3.66±6.87
2.52±6.18 12.94±18.98
51.75±64.13*
14.86±15.51*
Number of patients reintubated (n)
1
4
3
Mechanical ventilation after reintubation (h)
10
19.25±8.77
10.33±7.76
No of patients explored for excessive postoperative bleeding (n)
1
3
9
Number of patients who underwent revision of the primary procedure (n)
0
3
0
Complications (n)
3
14
12
Excessive bleeding
1
6
10
Low cardiac output
0
3
0
Lung collapse
0
1
1
Shunt thrombosis
0
2
0
Acute pulmonary edema
1
0
0
Contralateral pneumothorax
1
0
0
Acute renal failure
0
0
1
Tracheostomy
0
2
0
80.25±86.74
50.68±67.49
41.23±34.10
2*
4
0
ICU stay, h (mean±SD) Mortality (n)
*P
