Hypothermia and heart rate variability in a healthy newborn piglet model

Figure 1. HRV time domain variables and heart rate in six healthy, anaesthetised, newborn piglets exposed to 3 h of normothermia (38.5–39.5 °C) and 3 h of hypothermia (33.5–34.0 °C). Data are presented as mean with SD of 3 h of normothermia (NT) and mean with SD of 3 h of hypothermia (HT). P-value comparing NT with HT with paired t-test. NT: Normothermia; HT: Hypothermia; SDNN: Standard deviation of normal-to-normal interval; RMSSD: Root mean square of successive differences; logVLF: log-transformed power in the very low frequencies; logLF: log-transformed power in the low frequencies; logHF: log-transformed power in the high frequencies; HR: heart rate.

Figure 2. HRV frequency domain variables in six healthy, anaesthetised, newborn piglets exposed to 3 h of normothermia (38.5–39.5 °C) and 3 h of hypothermia (33.5–34.0 °C). Data are presented as mean with SD of 3 h of normothermia (NT) and mean with SD of 3 h of hypothermia (HT). P-value comparing NT with HT with paired t-test. NT: Normothermia; HT: Hypothermia; SDNN: Standard deviation of normal-to-normal interval; RMSSD: Root mean square of successive differences; logVLF: log-transformed power in the very low frequencies; logLF: log-transformed power in the low frequencies; logHF: log-transformed power in the high frequencies; HR: heart rate.

Figure 3. Clustered linear regression of heart rate and HRV measures in six healthy, anaesthetised, newborn piglets exposed to 3 h of normothermia (38.5–39.5 °C) and 3 h of hypothermia (33.5–34.0 °C). SDNN: Standard deviation of normal-to-normal interval; RMSSD: Root mean square of successive differences; log(VLF): log-transformed power in the very low frequencies; log(LF): log-transformed power in the low frequencies; log(HF): log-transformed power in the high frequencies; HR: heart rate.