Methylene blue as an adjuvant during cardiopulmonary resuscitation: an experimental study in rats

Xavier, Marcelo Souza; Vane, Matheus F.; Vieira, Roberta F.; Oliveira, Cristiano C.; Maia, Debora R.R.; Castro, Leticia U.C. de; Carmona, Maria José Carvalho; Auler Jr., José Otávio Costa; Otsuki, Denise Aya

doi:10.1016/j.bjane.2023.10.003

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Brazilian Journal of Anesthesiology

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ORIGINAL INVESTIGATION • para Braz. J. Anesthesiol. 74 (2) • 2024 • https://doi.org/10.1016/j.bjane.2023.10.003 copy

Methylene blue as an adjuvant during cardiopulmonary resuscitation: an experimental study in rats

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Introduction:

Methylene Blue (MB) has been shown to attenuate oxidative, inflammatory, myocardial, and neurological lesions during ischemia-reperfusion and has great potential during cardiac arrest. This study aimed to determine the effects of MB combined with epinephrine during cardiac arrest on myocardial and cerebral lesions.

Method:

Thirty-eight male Wistar rats were randomly assigned to four groups: the sham group (SH, n = 5), and three groups subjected to cardiac arrest (n = 11 /group) and treated with EPI 20 μg.kg⁻¹ (EPI), EPI 20 μg.kg⁻¹ + MB 2 mg.kg⁻¹ (EPI + MB), or saline 0.9% 0.2 ml (CTL). Ventricular fibrillation was induced by direct electrical stimulation in the right ventricle for 3 minutes, and anoxia was maintained for 5 minutes. Cardiopulmonary Resuscitation (CPR) consisted of medications, ventilation, chest compressions, and defibrillation. After returning to spontaneous circulation, animals were observed for four hours. Blood gas, troponin, oxidative stress, histology, and TUNEL staining measurements were analyzed. Groups were compared using generalized estimating equations.

Results:

No differences in the Returning of Spontaneous Circulation (ROSC) rate were observed among the groups (EPI: 63%, EPI + MB: 45%, CTL: 40%, p = 0.672). The mean arterial pressure immediately after ROSC was higher in the EPI+MB group than in the CTRL group (CTL: 30.5 [5.8], EPI: 63 [25.5], EPI+MB: 123 [31] mmHg, p = 0.007). Serum troponin levels were high in the CTL group (CTL: 130.1 [333.8], EPI: 3.70 [36.0], EPI +MB: 43.7 [116.31] ng/mL, p < 0.05).

Conclusion:

The coadministration of MB and epinephrine failed to yield enhancements in cardiac or brain lesions in a rodent model of cardiac arrest.

KEYWORDS
Cardiac arrest; Epinephrine; Hypoxia-ischemia; Injury; Methylene blue; Rats; Reperfusion

Groups	Heart			Brain
Groups	Troponin (ng/ml)	TUNEL	H&E¹ 1 (H&E) was used to assess the presence of vacuolization. (%)	TUNEL	H&E² 2 H&E staining of brain tissue indicated the existence of red neurons, suggesting hypoxic damage. Rats experienced only surgical intervention (SH, n = 11), or animals were subjected to CA and treated with epinephrine (EPI, n = 11), epinephrine and MB (EPI + MB, n = 11), or saline (CTL, n = 11). (%)
EPI	3.82^a a p < 0.05 vs. the SH group. (1.3-214.6)	15^a a p < 0.05 vs. the SH group. (12.9-24.7)	0	12.8 (6.6-19.2)	33
EPI+MB	43.72^a a p < 0.05 vs. the SH group. (5.9-200.6)	11.8 (6.9-19.6)	40	8.7 (3.9-17.2)	80
CTL	130.1^a a p < 0.05 vs. the SH group. (10.5-398)	19,1^a a p < 0.05 vs. the SH group. (12-24.6)	0	12.3 (6.6-22.2)	75
SH	0.021 (0.00-0.82)	10 (9.4-13.2)	0	5.5 (1.7-11.9)	0
p	0.013	0.071		0.308	0.349

		CTL	EPI	EPI+MB	SH
Mean BP	Initial	83.0 [7.6]	83 [10]^a a p < 0.05 vs. the SH Group	85 [16]^a a p < 0.05 vs. the SH Group	70.5 [2.5]
	ROSC	30.5 [5.8]	63 [25.5]^b b p < 0.05 vs. the CTL group , ^d d p < 0.05 vs. initial.	123 [31]^b b p < 0.05 vs. the CTL group	–
	Final	67.5 [28.6]^c c p < 0.05 vs. ROSC	77.0 [11]	67.0 [12]^c c p < 0.05 vs. ROSC	69.0 [5.7]
Diastolic BP	CPR	17.5 [1.9]	27.0 [16.5]^b b p < 0.05 vs. the CTL group	32.0 [14.5]^b b p < 0.05 vs. the CTL group	–
HR	Initial	267 [35.5]	276 [53.5]	267 [109]	204 [43]
	ROSC	250 [53.6]	270 [67.5]	254 [66.2]	–
	Final	211 [56.5]	211 [56.5]	290 [60]	200 [24.4]

Sociedade Brasileira de Anestesiologia (SBA) Rua Professor Alfredo Gomes, 36, Botafogo , cep: 22251-080 - Rio de Janeiro - RJ / Brasil , tel: +55 (21) 97977-0024 - Rio de Janeiro - RJ - Brazil
E-mail: editor.bjan@sbahq.org

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[1] * Corresponding author E-mail: denise.otsuki@hc.fm.usp.br (D.A. Otsuki).