Keywords
magnetic resonance imaging - anesthesia - pediatric patients - neutrophil–lymphocyte
ratio
Introduction
The frequency of magnetic resonance imaging (MRI) scans in pediatric patients has
increased in recent years.[1] The MRI has become the preferred diagnostic procedure for many conditions because
it is a noninvasive and radiation-free diagnostic procedure.
An MRI scan can take ∼10 to 30 minutes. It is quite noisy, and the patient is moved
into a narrow cylinder with limited access.[2] The patient must lie motionless inside a tunnel-like magnetic coil during the MRI
scan.[3] Several factors related to MRI can cause fear, agitation, and anxiety in patients,
including an unfamiliar environment, the presence of unknown staff, and lengthy scan
times.[4]
There are a variety of drugs available for sedation for those undergoing MRI. In this
study, four drug groups (propofol, ketamine, midazolam, and thiopental) were analyzed
retrospectively. These anesthetic agents are widely used for sedation, but they all
have their advantages and disadvantages. Unfortunately, there is not a perfect anesthetic
agent, and some complications observed after sedation can be related to the patient's
primary disease. In this study, we aimed to determine the relationship between sedative
agents and complications after the sedation. Also, we aimed to determine the drug
group that would provide optimum image quality during MRI and at the same time create
minimal complications. Ketamine dissociates the thalamus from the limbic cortex, which
causes dissociative anesthesia. Clinically, the patient appears conscious but unable
to respond. The ventilatory drive is minimally affected. Ketamine also has analgesic
and amnesic effects, but it increases cerebral oxygen consumption, cerebral blood
flow, and intracranial pressure.[5] Midazolam is a benzodiazepine that can be administered orally, intramuscularly,
and intravenously to provide premedication, sedation, or, less commonly, to induce
general anesthesia. The United States Food and Drug Administration has not approved
oral administration of midazolam. Benzodiazepines have minimal cardiovascular depressant
effects. Moreover, small doses of midazolam can result in respiratory arrest.[5] Thiopental is a barbiturate with hypnotic and anticonvulsant effects. Thiopental
also decreases intracranial pressure that also has hemodynamic and respiratory depression
effects.[5] In recent years, propofol has become the first choice for sedation, but it can cause
respiratory depression and arterial hypotension. However, propofol also has some advantages
such as short duration of action and some antiemetic properties. Therefore, it is
clear that the anesthetic drug of choice must be chosen according to the comorbidities
of the patient. For example, ketamine does not cause respiratory depression, but we
cannot use it in a patient with elevated intracranial pressure.
Materials and Methods
After approval by the Institutional Ethics Committee (date:28/05/2020 and issue number:
KAEK-354), we performed a retrospective observation of medical records of patients
aged between 1 month and 18 years old with an American Society of Anesthesiologists
(ASA) Physical Status Classification of 1 to 3, who received sedation for MRI between
February 1, 2017, and February 1, 2018, at Akdeniz University Hospital. We observed
that children received one of the four combinations of anesthetic drugs; group 1 received
midazolam (Sedazolam, Monem Farma, Ankara, Turkey), propofol (Lipuro, Braun, Melsungen
Germany), and ketamine (Ketax Vem Medikal, Istanbul, Turkey); group 2 received midazolam
and ketamine; group 3 received midazolam and thiopental (Pental Sodium, Ibrahim Ethem,
Istanbul, Turkey); and group 4 received midazolam and propofol combination for sedation
by choice of the attending anesthesiologist. The anesthetic choice decision was made
by the anesthesiologists with respect to the patient's age, comorbidities, and the
specifications of the procedure applied. Patients who had epilepsy did not receive
ketamine for sedation. The anesthetic choice, airway management, and monitoring were
made according to the guideline for monitoring and management of pediatric patients
during and after sedation for diagnostic and therapeutic procedures.[6]
[7] The anesthetic agents were also chosen according to the procedures and the duration
of action of the anesthetic drug as bolus doses. Additional bolus doses of anesthetics
were added if necessary ([Table 1]). All patients had oxygen therapy via a nasal cannula during sedation. When the
patient's oxygen saturation decreased, the MRI screening was stopped, and the patient
was evaluated. If the patient had mechanical obstruction with the tongue obstructing
the upper airway because of sedation, an oral airway and jaw suspension maneuver was
applied. If the patient had shallow breathing, the patient was ventilated with an
Ambu-mask or intubated if necessary. Furthermore, if the patient had low oxygen saturation
due to laryngospasm or bronchospasm, the patient was treated with positive pressure
ventilation with an Ambu-mask, inhaled β2-agonists, and intravenous steroids.
Table 1
Anesthetic drugs
|
Group 1 (mean ± SD)
|
Group 2 (mean ± SD)
|
Group 3 (mean ± SD)
|
Group 4 (mean ± SD)
|
|
Propofol (mg.kg−1)
|
1.43 ± 0.56
|
0
|
0
|
1.90 ± 0.83
|
|
Ketamine (mg.kg−1)
|
1.45 ± 0.63
|
1.92 ± 0.96
|
0
|
0
|
|
Midazolam (mg.kg−1)
|
0.07 ± 0.03
|
0.08 ± 0.05
|
0.08 ± 0.03
|
0.08 ± 0.03
|
|
Thiopental (mg.kg−1)
|
0
|
0
|
4.25 ± 1.30
|
0
|
Abbreviation: SD, standard deviation.
Note: Anesthetic drugs used in each group were given as mean ± SD and mg/kg−1. Values are given as mean ± SD.
Study data obtained for analysis included age, weight, gender, ASA classification,
diagnosis by service, preexisting comorbidities, type of MRI (i.e., site on the body),
preoperative complete blood counts (CBC), preoperative blood urea nitrogen (BUN),
creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), peripheral
oxygen saturation (SpO2), respiratory rate, heart rate, and anesthesia time. Preoperative
CBC, BUN, creatinine, ALT, and AST tests were obtained at the preoperative visit,
which usually occurred 1 or 2 days before the MRI scan. CBC measurements were done
using Sysmex XN 1000 hematology analyzer (Sysmex America Inc., Illinois, United States),
and serum creatinine, BUN, ALT, and AST measurements were done by using commercial
kits with Siemens ADVIA Chemistry 2400 auto-analyzer (Siemens Healthineers Diagnostics
Ltd, Erlangen, Germany). After the procedure, all patients were monitored in a postanesthesia
care unit, and heart rates, respiratory rates, SpO2, mean arterial pressure, and complications
like itching, nausea, vomiting, and modified Aldrete scores recovery and discharge
times were recorded. Patients were discharged from the hospital if the patient's modified
Aldrete score was equal to or higher than nine and without any complication for at
least 30 minutes. Patients were called by an anesthesiologist and questioned about
complications, which typically occurred a week after the procedure.
Statistical Analysis
The patients' demographic data, diagnosis, and type of MRI procedures were analyzed
by descriptive statistics. The relations between preoperative laboratory findings,
dosages of anesthetic agents, and complications were analyzed by correlation analysis.
The association between complications and the type of MRI and anesthetic drugs were
analyzed by analysis of variance, and Duncan's test was used to determine the difference
between groups. The results are summarized as the β coefficient with 95% confidence
intervals and p-values. Statistical analysis was performed using the Statistical Package for Social
Sciences (SPSS) software program.
Results
Nine-hundred eighty pediatric patients' records were examined. Three patients were
excluded from the study because they were unable to be reached by phone for questioning
in regard to any complications experienced a week after the procedure. As such, a
total of 977 patients were enrolled in the study. One-hundred fifty-nine patients
received midazolam, propofol, and ketamine in group 1. Twenty-four patients received
midazolam and ketamine in group 2. One-hundred ninety-nine patients received midazolam
and thiopental in group 3, and 595 patients received midazolam and propofol in group
4 for sedation for MRI scanning. There was not any statistical difference between
demographic data of the patients between groups ([Table 2]). Details of comorbidities of the patients were also given in [Table 2].
Table 2
Demographic data and comorbidities of the patients
|
Group 1
n = 159 (16.3%)
|
Group 2
n = 24 (2.5%)
|
Group 3
n = 199 (20.4%)
|
Group 4
n = 595 (60.9%)
|
|
Gender (F/M)
|
59/100
|
16/8
|
98/101
|
247/348
|
|
Age groups (y)
|
3.26 ± 2.25
|
3.48 ± 3.62
|
3.77 ± 3.87
|
3.79 ± 3.56
|
|
0–1
|
30
|
5
|
42
|
101
|
|
1–7
|
114
|
18
|
124
|
411
|
|
7–18
|
15
|
1
|
33
|
81
|
|
Weight (kg)
|
15.18 ± 8.81
|
13.69 ± 7.45
|
16.19 ± 12.28
|
16.21 ± 11.27
|
|
ASA classification
|
2
|
2
|
2
|
2
|
|
1
|
42
|
0
|
28
|
104
|
|
2
|
107
|
24
|
144
|
449
|
|
3
|
10
|
0
|
27
|
42
|
|
Epilepsy
|
2 (1.3%)[a]
|
1 (4.2%)[b]
|
110 (55.3%)[c]
|
229 (38.5%)
|
|
Cerebrovascular event
|
1 (0.6%)
|
0
|
3 (1.5%)
|
1 (0.2%)
|
|
Intracranial bleeding
|
1 (0.6%)
|
0
|
8 (4.0%)
|
13 (2.2%)
|
|
Adenoid hyperplasia
|
14 (8.8%)
|
1 (4.2%)
|
15 (7.5%)
|
38 (6.4%)
|
|
Hypothyroidism
|
3 (1.9%)
|
1 (4.2%)
|
5 (2.5%)
|
14 (2.4%)
|
|
Intracranial mass
|
7 (4.4%)
|
0
|
24 (12.1%)
|
67 (11.34%)
|
|
Congenital heart disease
|
11 (6.9%)
|
3 (12.5%)
|
13 (6.5%)
|
41 (6.9%)
|
|
Chronic heart failure
|
0
|
0
|
0
|
1 (0.2%)
|
|
Atrial fibrillation
|
0
|
0
|
0
|
1 (0.2%)
|
|
Acute kidney failure
|
0
|
0
|
0
|
1 (0.2%)
|
|
Chronic kidney failure
|
1 (0.6%)
|
0
|
1 (0.5%)
|
3 (0.5%)
|
|
Syndrome
|
14 (8.8%)
|
4 (16.7%)
|
15 (7.5%)
|
50 (8.4%)
|
|
Genetic
|
3 (1.9%)
|
1 (4.2%)
|
1 (0.5%)
|
17 (2.9%)
|
|
MMR
|
22 (13.8%)
|
4 (16.7%)
|
30 (15.1%)
|
77 (12.9%)
|
|
Diabetes mellitus
|
0
|
0
|
0
|
0
|
|
Cerebral palsy
|
3 (1.9%)
|
1 (4.2%)
|
20 (10.1%)
|
33 (5.5%)
|
|
Hypertension
|
2 (1.3%)
|
0
|
0
|
3 (0.5%)
|
Abbreviations: ASA, American Society of Anesthesiologists; MMR, mental motor retardation.
Patients' genders (female/male), ages (years), weights (kg), ASA risk classifications,
and existing comorbidities of the patients are listed as the number (n) of the patients and the percentile (%) of the patients. Syndrome stands for a coexistence
of a congenital syndrome. Genetic stands for coexistence of a genetic abnormality.
Statistical analysis is done by one-sample chi-squared test.
a
p = 0.000 and p = 0.000 versus group 2 and group 4.
b
p = 0.000 and p = 0.000 versus group 3 and group 4.
c
p = 0.000 versus group 4.
Epilepsy rates were significantly lower in the patients in groups 1 and 2 than the
patients in groups 3 and 4 ([Table 2]). The patients in group 1 had significantly higher vomiting rates than the patients
in group 2 (p = 0.002), group 3 (p = 0.01), and group 4 (p = 0.025). The patients in group 4 also had higher vomiting rates than the patients
in group 2 (p = 0.002; [Table 3]). We observed bronchospasm in the patients in group 1 (p = 0.006) and group 3 (p = 0.001) more than the patients in group 4 ([Table 3]). The patients in groups 2 and 3 experienced more nausea than the patients in group
4 within a week after the procedure (p = 0.007; [Table 3]). There was also more vomiting in group 2 when compared with patients in groups
1, 3, and 4 (p = 0.001; [Table 3]). Procedure time was significantly longer in group 1 than group 4 (p < 0.001), and it was longer in group 4 than group 3 (p = 0.046; [Table 4]). Recovery times were longer in group 3 (p < 0.001) and group1 (p = 0.023) then group 4 ([Table 4]). The modified Aldrete scores were similar between groups. One hour after the procedure,
respiratory rates were higher in group 1 (p < 0.001) and group 3 (p = 0.006) than in group 4. Two hours after the procedure, respiratory rates were higher
in group 1 than group 3 (p = 0.026) and group 4 (p = 0.001; [Table 4]). Mean heart rates were higher in the patients in group 2 than the patients in group
3 (p = 0.007), and mean heart rates were higher in the patients in group 1 (p < 0.001), group 2(p < 0.001), and group 3 (p < 0.001) then the patients in group 4 ([Table 4]). In the patients in group 2, no nausea or vomiting was seen right after the procedure.
Still, 1 week later, nausea (p = 0.007) and vomiting (p = 0.001) ratios were significantly higher than the patients in the other groups.
Nausea and vomiting ratios were lower in the patients in group 4 ([Table 3]). There were no significant differences between the other parameters. In group 4,
minimum side effects were seen. In group 3, significantly higher mean platelet volume
(MPV) was recorded than group 4 ([Table 5]) (p < 0.001). There were not any significant differences between neutrophil–lymphocyte
(N/L) ratios related to the anesthetic drugs used. However, the patients who had nausea
(p = 0.012) and vomiting (p = 0.012) within the week after the procedure had statistically significant lower
N/L values but had not no difference in MPV values ([Tables 5]
[6]).
Table 3
Complications seen after the procedure
|
Complications
|
Group 1
n =159 (16.3%)
|
Group 2
n = 24 (2.5%)
|
Group 3
n = 199 (20.4%)
|
Group 4
n = 595 (60.9%)
|
|
Hospitalization
|
1 (0.7%)
|
1 (4.5%)
|
4 (2.2%)
|
8 (1.4%)
|
|
Bronchospasm
|
4 (2.5%)
|
0
|
6 (3%)
|
2 (0.3%)[a]
|
|
Bradycardia
|
1 (0.6%)
|
0
|
1 (0.5%)
|
0
|
|
Itching
|
0
|
0
|
0
|
4 (0.7%)
|
|
Rash
|
0
|
0
|
0
|
0
|
|
Nausea
|
9 (5.7%)[b]
|
0
|
2 (1%)
|
13 (2.2%)
|
|
Vomiting
|
9 (5.7%)[c]
|
0[d]
|
2 (1%)
|
10 (1.7%)
|
|
Dizziness
|
0
|
0
|
2 (1%)
|
2 (0.3%)
|
|
Headache
|
3 (1.9%)
|
0
|
2 (1%)
|
3 (0.5%)
|
|
Stomachache
|
2 (1.3%)
|
1 (4.2%)
|
3 (1.5%)
|
1 (0.7%)
|
|
Respiratory depression
|
1 (0.6%)
|
0
|
0
|
2 (0.3%)
|
|
Complications in a week
|
|
Nausea
|
6 (4%)
|
4 (17.4%)[e]
|
6 (3.3%)
|
13 (2.3%)
|
|
Vomiting
|
6 (4%)
|
5 (21.7%)[f]
|
7 (3.8%)
|
12 (2.1%)
|
|
Rash
|
4 (2.7%)
|
1 (4.3%)
|
1 (0.5%)
|
5 (0.9%)
|
|
Urinary retention
|
1
|
0
|
1
|
2
|
|
Cardiac arrest
|
0
|
0
|
0
|
0
|
|
Seizure
|
3 (2%)
|
0
|
12 (6.6%)
|
23 (4%)
|
Complications seen right after the procedure and within a week after the procedure
were given as the number (n) of the patients and percentile (%) of the patients.
Values are given as
n
(%). Statistical analyses are done by Fisher's exact test.
a
p = 0.006 and p = 0.001 versus group 1 and group 3.
b
p = 0.02 versus group 4.
c
p = 0.02, p = 0.01 and p = 0.005 versus group 2, group 3 and group 4.
d
p = 0.002 versus group 4.
e
p = 0.007 versus group 3 and group 4.
f
p = 0.001 versus group 1, group 3, and group 4.
Table 4
Parameters of groups after procedure
|
Group 1 (mean ± SD)
|
Group 2 (mean ± SD)
|
Group 3 (mean ± SD)
|
Group 4 (mean ± SD)
|
|
Procedure times
|
19.81 ± 9.11
|
22.54 ± 20.85
|
17.16 ± 6.77
|
17.47 ± 8.02[a]
|
|
Aldrete score
|
8.88 ± 0.5
|
9.12 ± 0.5
|
9.01 ± 0.3
|
8.87 ± 0.7
|
|
Recovery times
|
1.86 ± 0.43
|
2.04 ± 0.44
|
1.90 ± 0.33
|
1.80 ± 0.34[b]
|
|
Respiratory rates 1 hour later
|
26.26 ± 1.58
|
25.54 ± 2.5
|
26.08 ± 1.87
|
25.42 ± 2.18[c]
|
|
Respiratory rates 2 hours later
|
25.26 ± 1.71[d]
|
24.58 ± 2.04
|
24.70 ± 1.77
|
24.53 ± 3.67
|
|
Heart rates 1 hour later
|
112.78 ± 14.82
|
123.71 ± 18.35[e]
|
110.13 ± 18.23
|
103.47 ± 16.8[
f
]
|
|
Heart rates 2 hours later
|
112.31 ± 14.28
|
118.42 ± 17.58
|
109.05 ± 15.87
|
104.63 ± 16.11[
g
]
|
|
SpO2 1 hour later
|
98.77 ± 1.42
|
98.63 ± 1.47
|
98.55 ± 1.52
|
98.66 ± 1.7
|
|
SpO2 2 hours later
|
99.43 ± 0.98
|
99.13 ± 0.95
|
99.43 ± 0.97
|
99.34 ± 1.12
|
|
Preoperative Hb value(mg/dL)
|
11.80 ± 1.29
|
12.48 ± 1.41
|
11.92 ± 1.24
|
12.36 ± 1.38
|
|
Preoperative hemathocrit value (%)
|
35.65 ± 3.70
|
37.96 ± 4.12
|
35.88 ± 3.78
|
35.87 ± 3.89
|
|
Preoperative WBC (1,000 mm3)
|
9497.04 ± 3688.06
|
9665.22 ± 2715.21
|
9195.78 ± 3207.8
|
9030.21 ± 3260.94
|
|
Preoperative neutrophil (1,000 mm3)
|
3955.28 ± 2440.93
|
3926.09 ± 2085.28
|
3511.41 ± 1738.7
|
3636.98 ± 1924.91
|
|
Preoperative lymphocyte (1,000 mm3)
|
4328.93 ± 2048.51
|
4556.52 ± 1598.81
|
4458.28 ± 2178.8
|
4288.65 ± 2101.70
|
|
Preoperative neutrophil (%)
|
40.55 ± 14.51
|
38.70 ± 14.34
|
38.42 ± 14.11
|
39.79 ± 14.49
|
|
Preoperative lymphocyte (%)
|
45.33 ± 13.14
|
46 ± 12.88
|
47.54 ± 13.18
|
46.59 ± 13.82
|
|
Preoperative platelet (1,000 mm3)
|
377.83 ± 126.76
|
380.17 ± 114.60
|
362.16 ± 119.49
|
346.99 ± 106.69
|
|
Preoperative BUN (mg/dL)
|
11.71 ± 4.68
|
9.75 ± 3.20
|
11.13 ± 5.91
|
11.16 ± 4.26
|
|
Preoperative creatinine (mg/dL)
|
0.29 ± 0.11
|
0.20 ± 0.08
|
0.31 ± 0.16
|
0.30 ± 0.23
|
|
Preoperative ALT (U/L)
|
26.26 ± 45.77
|
18.75 ± 2.75
|
23.70 ± 15.70
|
20.19 ± 11.62
|
|
Preoperative AST (U/L)
|
37.32 ± 45.68
|
33.0 ± 8.76
|
37.73 ± 16.54
|
29.60 ± 15.69
|
Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN,
blood urea nitrogen; MRI, magnetic resonance imaging; SD, standard deviation; SpO2, peripheral oxygen saturation; WBC, white blood cell.
Total MRI scan times, Aldrete scores before the patients were discharged, recovery
times; time spent after the MRI scan until the patients are discharged, respiratory
rates 1 and 2 hours after the MRI scan and heart rates 1 and 2 hours after the MRI
scan were given as mean ± SD.
Values are given as mean ± SD Statistical analysis was done by Kruskal–Wallis one way analysis of variance on ranks
with multiple comparisons by Bonferroni correction.
a
p = 0.046 and p = 0.000 versus group 3 and group 1.
b
p = 0.000 and p = 0.023 versus group 3 and group 1.
c
p = 0.000 and p = 0.006 versus group 1 and group 3.
d
p = 0.026 and p = 0.001 versus group 3 and group 4.
e
p = 0.007 versus group 3.
f
p = 0.000, p = 0.000 and p = 0.000 versus group 1, group 2, and group 3.
g
p = 0.000, p = 0.000 and p = 0.000 versus group 1, group 2, and group 3.
Table 5
N/L ratios and MPV values before the procedure
|
Group 1
|
Group 2
|
Group 3
|
Group 4
|
|
N/L
|
1.09 ± 0.75
|
1.01 ± 0.72
|
1.04 ± 1.27
|
1.10 ± 1.03
|
|
N/L percentile
|
1.09 ± 0.75
|
0.99 ± 0.70
|
1.05 ± 1.35
|
1.09 ± 0.98
|
|
MPV
|
7.71 ± 0.85
|
7.67 ± 1.04
|
7.94 ± 0.92[a]
|
7.61 ± 1.02
|
Abbreviations: CBC, complete blood count; MPV, mean platelet volume; N/L, neutrophil–lymphocyte; SD, standard deviation.
Neutrophil lymphocyte ratios calculated from preoperative CBC test and percentile
of neutrophil and lymphocyte again calculated from CBC test and mean platelet volume
values are given as mean ± SD of the groups.
Values are mean ± SD.
a
p = 0.000 versus group 4. Statistical analysis was done by Tamhane test and multiple
comparisons by Welch test.
Table 6
Relationship between nausea and vomiting and preoperative N/L percentile ratios and
MPV
|
Total number
|
N/L percentile (mean ± SD)
|
MPV (mean ± SD)
|
|
Nausea not seen after procedure
|
941
|
1.08 ± 1.04
|
7.69 ± 0.99
|
|
Nausea seen after procedure
|
24
|
1.12 ± 0.76
|
7.80 ± 0.84
|
|
Vomiting not seen after procedure
|
944
|
1.08 ± 1.03
|
7.68 ± 0.98
|
|
Vomiting seen after procedure
|
21
|
1.15 ± 0.80
|
7.67 ± 0.82
|
|
Nausea not seen in a week
|
896
|
1.07 ± 0.89[a]
|
7.67 ± 0.98
|
|
Nausea seen in a week
|
27
|
0.73 ± 0.55
|
7.79 ± 0.97
|
|
Vomiting not seen in a week
|
892
|
1.07 ± 0.89[b]
|
7.67 ± 0.98
|
|
Vomiting seen in a week
|
30
|
0.76 ± 0.60
|
7.91 ± 1.13
|
Abbreviations: MPV, mean platelet volume; N/L, neutrophil–lymphocyte; SD, standard deviation.
Relationship between nausea and vomiting seen in all patients and preoperative calculated
neutrophil lymphocyte percentile ratios and mean platelet volume values were given
as mean ± SD.
a
p = 0.012 versus nausea not seen in a week.
b
p = 0.012 versus vomiting not seen in a week.
Discussion
The present study retrospectively reviewed anesthetic choices used for sedation during
MRI for pediatric patients. We aimed to determine complications arising from these
processes in our institution. To this extent, patients' records were reviewed for
anesthetic choices, anesthetic environment, complications after the procedure, and
complications developed a week after the procedure. It was determined that in our
institution, ketamine and propofol combination was used for most of the patients.
Still, the midazolam and propofol combination has the lowest complication ratio, and
N/L ratio rates were lower in patients with nausea and vomiting seen in a week after
the procedure.
An MRI scan has become the preferred diagnostic procedure for many conditions because
it is a noninvasive, radiation-free diagnostic procedure. It is a lengthy and noisy
procedure, however, and requires immobility. Also, monitorization is a problem because
classic monitors cannot be used in a magnetic field. There are particular types of
equipment for MRI rooms. Our institution lacks this special equipment, so we monitor
the patients with pulse oximetry outside the MRI room, with the pulse-oximetry probe
attached to the patient with an extension line through a hole at the window of the
MRI room. Another problem in an MRI environment is that metal objects can become projectiles,
so the patient must not have any metal objects on them in the MRI room. Sedation or
anesthesia is required when the child is uncooperative, or the child has to be at
rest during the procedure. The anesthetist must provide a motionless patient during
the procedure without interfering with the patient's safety. Access to the patient
is limited during an MRI. To prevent the side effects of anesthetic drugs, combinations
of anesthetic drugs are used. Most children who need MRI have some comorbidities such
as neurological diseases, vascular malformation, or oncological tumor growth. In this
group of patients, epilepsy, intellectual disability, or spasticity is common.[8]
[9] The anesthetist must consider these conditions when managing sedation or anesthesia
for MRI in children.
Metals can interfere with the image quality of the MRI and can cause side effects
in the patient like a warming sensation. Also, metal devices such as pacemakers malfunction
and get damaged by the magnetic field. As such, some specific considerations must
be given for the design of the anesthesia workstation in an MRI environment. The workstation
must also contain a ventilator, anesthetic gas measurement, capnography, pulse oximetry,
electrocardiogram, blood pressure, and respiratory frequency monitors. The ventilator
used for pediatric patients must contain compliance compensation. Finally, it must
be kept in mind that if an emergency stop is needed, the result is time and cost-consuming.
In the end, the primary goals to be achieved are maximum patient safety, successful
scanning, and paramount image quality.[2]
According to the American Academy of Pediatrics, sedation in children is defined in
four steps: anxiolysis, conscious sedation, deep sedation, and anesthesia. The main
goal of sedation for diagnostic and therapeutic procedures in the pediatric patient
is to ensure the patient's safety and prevent the pain and discomfort of the patient.
At the same time, the patient's movement must be avoided to ensure the quality of
the images being obtained. Finally, the patient must be safely discharged at the end
of the procedure.[2]
Concerning children and MRI, deep sedation is required for examination in most cases
because of noise and the narrowness of the bore. Stopping an MRI scan is expensive
and ineffective; thus, the failure rate must be minimized. Preoperative fasting is
the same as general anesthesia. During the procedure, intravenous access and monitoring
are also mandatory, and an experienced anesthetist and emergency equipment must be
nearby.[2] It must be kept in mind that disabled children are three times more prone to hypoxia
under sedation.[9] The patient has to be under the supervision of an experienced anesthetist because
of the limited access and view during the MRI scan. If anything goes wrong during
the MRI scan, such as hypoventilation, the management of the patient must have been
practiced previously by the team, as interfering with such a patient can be challenging
and time-consuming. Also, newborns are known to be vulnerable to desaturation, and
bradycardia occurs immediately after desaturation. An anesthesiologist must consider
these conditions when managing proper anesthesia and monitoring for pediatric patients
during MRI, which must be kept in mind when choosing a suitable anesthetic procedure
and monitoring pediatric patients.[2]
We chose anesthetic drugs according to the patient's comorbidities and procedure time.
Epilepsy rates were lower in the patients in groups 1 and 2 because we do not prefer
ketamine for patients with epilepsy. Midazolam and ketamine combination was preferred
for more lengthy procedures since midazolam has a longer duration of action. Midazolam
and pentothal combination was preferred for shorter procedures since thiopental has
a shorter duration of action. None of our patients had low SpO2 levels or bradycardia.
Since ketamine increases heart rate, tachycardia was recorded in the midazolam and
ketamine groups.[10] After 1 hour from the procedure, respiration rates were lower with midazolam and
ketamine, then ketamine and propofol combination, because midazolam's duration of
action is more prolonged than propofol.[10] Again, respiration rates with midazolam and thiopental were higher than midazolam
and propofol because propofol's duration of action is more prolonged than thiopental.[10] Despite statistically significant differences in respiratory rates and heart rates
between groups, these differences were not clinically significant. None of the patients
had respiratory complications during the perioperative period. The SpO2 levels did
not differ between groups. Mallory et al found in their multicenter study that propofol
provides more efficient and effective sedation than pentobarbital for children undergoing
MRI.[11] Pediatric sedation research consortium reported, in a study which was conducted
on 49,836 children at 37 centers, that according to these findings, propofol is a
good anesthetic choice without serious side effects when applied by a well-organized
anesthesia team.[12] The data indicate that propofol sedation/anesthesia is unlikely to yield severe
adverse outcomes in a collection of institutions with highly motivated and organized
sedation/anesthesia services.[12] We also chose propofol combinations for most of our patients. Schmitz et al reported
that ketamine at induction with a reduced propofol infusion rate leads to faster postanesthetic
recovery.[13] We did not find any differences between the groups' recovery times, but we also
found that we mainly chose ketamine with propofol combination. Only a small number
of the patients received ketamine and midazolam combination. In the midazolam and
ketamine group, nausea and vomiting were not seen right after the procedure, but the
nausea and vomiting ratio was highest during the week after the procedure. The patients
who experienced less nausea and vomiting had a lower N/L ratio.
The N/L ratio is a well-known inflammation marker.[14]
[15]
[16]
[17]
[18]
[19] Inflammation and nausea and vomiting seem to correlate.[14] It is well known that dexamethasone is an antiemetic agent.[20]
[21] Its estimated mechanism of action is preventing activation of the chemoreceptor
trigger zone by activation of glucocorticoid receptors found within the bilateral
solitary tract nucleus and area postrema of the brain stem, implicated as a central
emetogenic mediator.[22] Another theory centers around the anti-inflammatory properties of dexamethasone,
which may help reduce inflammatory reaction's leading parasympathetically driven stimulation
of the chemoreceptor trigger zone.[23]
[24] MPV is another marker of an inflammatory response, but it is a weak marker.[25]
[26] In our study, we also did not find any correlation between nausea and vomiting and
MPV values. Only in the third group, we discovered that MPV values were higher than
the other groups. To our knowledge, no studies have shown the effects of anesthetic
drugs on MPV values. Further investigations can be planned to investigate the relation
between anesthetic drugs and MPV values.
Our study has some limitations; as this study was a retrospective study, the number
of patients of the groups was not equal. Furthermore, comorbidities like epilepsy
were not an equal number between groups. These situations cause some difficulties
in statistical analyses.
Conclusion
All four anesthetic combinations can be used safely during MRI for children. Minimum
side effects were achieved with midazolam and propofol combination. Anesthetists must
choose the proper anesthetic technique according to the procedure's time and the patient's
comorbidities. The essential issue is close monitoring both during and after the procedure.
Notably, midazolam and propofol combination seems to have a minimum complication ratio.
