Comparison of various vasopressin doses to epinephrine during cardiopulmonary resuscitation in asphyxiated neonatal piglets

Background Current neonatal resuscitation guidelines recommend epinephrine for cardiac arrest. Vasopressin might be an alternative during asphyxial cardiac arrest. We aimed to compare vasopressin and epinephrine on incidence and time to return of spontaneous circulation (ROSC) in asphyxiated newborn piglets. Design/methods Newborn piglets (n = 8/group) were anesthetized, intubated, instrumented, and exposed to 30 min of normocapnic hypoxia, followed by asphyxia and asystolic cardiac arrest. Piglets were randomized to 0.2, 0.4, or 0.8IU/kg vasopressin, or 0.02 mg/kg epinephrine. Hemodynamic parameters were continuously measured. Results Median (IQR) time to ROSC was 172(103–418)s, 157(100–413)s, 122(93–289)s, and 276(117–480)s for 0.2, 0.4, 0.8IU/kg vasopressin, and 0.02 mg/kg epinephrine groups, respectively (p = 0.59). The number of piglets that achieved ROSC was 6(75%), 6(75%), 7(88%), and 5(63%) for 0.2, 0.4, 0.8IU/kg vasopressin, and 0.02 mg/kg epinephrine, respectively (p = 0.94). The epinephrine group had a 60% (3/5) rate of post-ROSC survival compared to 83% (5/6), 83% (5/6), and 57% (4/7) in the 0.2, 0.4, and 0.8IU/kg vasopressin groups, respectively (p = 0.61). Conclusion Time to and incidence of ROSC were not different between all vasopressin dosages and epinephrine. However, non-significantly lower time to ROSC and higher post-ROSC survival in vasopressin groups warrant further investigation. Impact Time to and incidence of ROSC were not statistically different between all vasopressin dosages and epinephrine. Non-significantly lower time to ROSC and higher post-ROSC survival in vasopressin-treated piglets. Overall poorer hemodynamic recovery following ROSC in epinephrine piglets compared to vasopressin groups. Human neonatal clinical trials examining the efficacy of vasopressin during asphyxial cardiac arrest will begin recruitment soon.


Background
3 a.Include sufficient scientific background (including relevant references to previous work) to understand the motivation and context for the study, and explain the experimental approach and rationale.
b. Explain how and why the animal species and model being used can address the scientific objectives and, where appropriate, the study's relevance to human biology.

4-5
Objectives 4 Clearly describe the primary and any secondary objectives of the study, or specific hypotheses being tested.

Ethical statement 5
Indicate the nature of the ethical review permissions, relevant licences (e.g.Animal [Scientific Procedures] Act 1986), and national or institutional guidelines for the care and use of animals, that cover the research.

Study design 6
For each experiment, give brief details of the study design including: a.The number of experimental and control groups.
b. Any steps taken to minimise the effects of subjective bias when allocating animals to treatment (e.g.randomisation procedure) and when assessing results (e.g. if done, describe who was blinded and when).
c.The experimental unit (e.g. a single animal, group or cage of animals).
A time-line diagram or flow chart can be useful to illustrate how complex study designs were carried out.

5-9
Experimental procedures 7 For each experiment and each experimental group, including controls, provide precise details of all procedures carried out.For example: a.How (e.g.drug formulation and dose, site and route of administration, anaesthesia and analgesia used [including monitoring], surgical procedure, method of euthanasia).Provide details of any specialist equipment used, including supplier(s).
b.When (e.g.time of day).
d.Why (e.g.rationale for choice of specific anaesthetic, route of administration, drug dose used).

5-9
Experimental animals 8 a. Provide details of the animals used, including species, strain, sex, developmental stage (e.g.mean or median age plus age range) and weight (e.g.mean or median weight plus weight range).
b. Provide further relevant information such as the source of animals, international strain nomenclature, genetic modification status (e.g.knock-out or transgenic), genotype, health/immune status, drug or test naïve, previous procedures, etc.

Housing and husbandry
9 Provide details of: a. Housing (type of facility e.g.specific pathogen free [SPF]; type of cage or housing; bedding material; number of cage companions; tank shape and material etc. for fish).
b. Husbandry conditions (e.g.breeding programme, light/dark cycle, temperature, quality of water etc for fish, type of food, access to food and water, environmental enrichment).
c. Welfare-related assessments and interventions that were carried out prior to, during, or after the experiment.

5-9
Sample size 10 a. Specify the total number of animals used in each experiment, and the number of animals in each experimental group.
b. Explain how the number of animals was arrived at.Provide details of any sample size calculation used.
c. Indicate the number of independent replications of each experiment, if relevant.

Allocating animals to experimental groups
11 a.Give full details of how animals were allocated to experimental groups, including randomisation or matching if done.
b. Describe the order in which the animals in the different experimental groups were treated and assessed.

5-9
Experimental outcomes 12 Clearly define the primary and secondary experimental outcomes assessed (e.g.cell death, molecular markers, behavioural changes).

5-9
Statistical methods 13 a.Provide details of the statistical methods used for each analysis.
b. Specify the unit of analysis for each dataset (e.g.single animal, group of animals, single neuron).
c. Describe any methods used to assess whether the data met the assumptions of the statistical approach.

Baseline data
14 For each experimental group, report relevant characteristics and health status of animals (e.g.weight, microbiological status, and drug or test naïve) prior to treatment or testing.(This information can often be tabulated).

9, Table 1&2
Numbers analysed 15 a. Report the number of animals in each group included in each analysis.Report absolute numbers (e.g.10/20, not 50% 2 ).
b.If any animals or data were not included in the analysis, explain why.9-10, Tables, Figures

Outcomes and estimation
16 Report the results for each analysis carried out, with a measure of precision (e.g. standard error or confidence interval).

9-10, Tables, Figures
Adverse events 17 a.Give details of all important adverse events in each experimental group.
b. Describe any modifications to the experimental protocols made to reduce adverse events.9-10, Tables, Figures

DISCUSSION
Interpretation/scientific implications 18 a.Interpret the results, taking into account the study objectives and hypotheses, current theory and other relevant studies in the literature.
b. Comment on the study limitations including any potential sources of bias, any limitations of the animal model, and the imprecision associated with the results 2 .
c. Describe any implications of your experimental methods or findings for the replacement, refinement or reduction (the 3Rs) of the use of animals in research.

Generalisability/ translation
19 Comment on whether, and how, the findings of this study are likely to translate to other species or systems, including any relevance to human biology.

10-14
Funding 20 List all funding sources (including grant number) and the role of the funder(s) in the study.