Department of Veterinary Clinical Science, College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea.
J Vet Sci. 2022 Nov;23(6):e68. doi: 10.4142/jvs.22090. Epub 2022 Jul 22.
Studies on anesthetized dogs regarding pulse pressure variation (PPV) are increasing. The influence of respiratory rate (RR) on PPV, in mechanically ventilated dogs, has not been clearly identified.
This study evaluated the influence of RR on PPV in mechanically ventilated healthy dogs after hemorrhage.
Five healthy adult Beagle dogs were premedicated with intravenous (IV) acepromazine (0.01 mg/kg). Anesthesia was induced with alfaxalone (3 mg/kg IV) and maintained with isoflurane in 100% oxygen. The right dorsal pedal artery was cannulated with a 22-gauge catheter for blood removal, and the left dorsal pedal artery was cannulated and connected to a transducer system for arterial blood pressure monitoring. The PPV was automatically calculated using a multi-parameter monitor and recorded. Hemorrhage was induced by withdrawing 30% of blood (24 mL/kg) over 30 min. Mechanical ventilation was provided with a tidal volume of 10 mL/kg and a 1:2 inspiration-to-expiration ratio at an initial RR of 15 breaths/min (baseline). Thereafter, RR was changed to 20, 30, and 40 breaths/min according to the casting lots, and the PPV was recorded at each RR. After data collection, the blood was transfused at a rate of 10 mL/kg/h, and the PPV was recorded at the baseline ventilator setting.
The data of PPV were analyzed using the Friedman test followed by the Wilcoxon signed-rank test ( < 0.05). Hemorrhage significantly increased PPV from 11% to 25% at 15 breaths/min. An increase in RR significantly decreased PPV from 25 (baseline) to 17%, 10%, and 10% at 20, 30, and 40 breaths/min, respectively (all < 0.05).
The PPV is a dynamic parameter that can predict a dog's hemorrhagic condition, but PPV can be decreased in dogs under high RR. Therefore, careful interpretation may be required when using the PPV parameter particularly in the dogs with hyperventilation.
关于脉压变异（PPV）的麻醉犬研究越来越多。尚未明确呼吸频率（RR）对机械通气犬 PPV 的影响。
本研究评估了机械通气健康犬出血后 RR 对 PPV 的影响。
5 只健康成年比格犬静脉（IV）预给药氯丙嗪（0.01mg/kg）。用阿法沙龙（3mg/kg IV）诱导麻醉，并在 100%氧气中用异氟烷维持。用 22 号导管经右背跖动脉插管采血，左背跖动脉插管并连接到压力换能器系统监测动脉血压。使用多参数监护仪自动计算并记录 PPV。通过 30 分钟内抽取 30%的血液（24mL/kg）来诱导出血。初始 RR 为 15 次/分时，采用 10mL/kg 的潮气量和 1:2 的吸气到呼气比进行机械通气（基线）。此后，根据铸造批次将 RR 改为 20、30 和 40 次/分，并在每个 RR 记录 PPV。收集数据后，以 10mL/kg/h 的速度输血，并在基线呼吸机设置下记录 PPV。
使用 Friedman 检验后，使用 Wilcoxon 符号秩检验对 PPV 数据进行分析（<0.05）。RR 为 15 次/分时，出血显著增加 PPV 从 11%到 25%。RR 增加显著降低了 PPV，从 25%（基线）分别降至 20、30 和 40 次/分时的 25%、17%、10%和 10%（均<0.05）。
PPV 是一个动态参数，可以预测犬的出血情况，但在 RR 较高的犬中，PPV 可能会降低。因此，在高 RR 犬中使用 PPV 参数时，可能需要谨慎解释。
