Tzortzi I. DVM, MSc student in the field of Anesthesia and Intensive Unit Care, Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
Varkoulis K. DVM, MSc, Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
Zapridis V. DVM, MRCVS, Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
Kazakos G. DVM, PhD, Αssociate Professor of Anesthesia and Intensive Unit Care, Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
Anagnostou T. DVM, PhD, dipl ECVAA, Αssociate Professor of Anesthesia and Intensive Unit Care, Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
Introduction
Pulse Pressure Variation (PPV) is a dynamic marker of fluid responsiveness. It is defined as the ratio of the difference between the maximum PP and minimum PP to the average of the two. It can be assessed in mechanically ventilated patients without arrythmias in whom blood pressure is measured invasively. PPV values over 11% are indicative of a positive response to fluid administration (fluid responders) while values below 9% are compatible with patients who cannot respond to further fluid administration (non-fluid responders) (Sano et al. 2018).
Materials and methods
The study included 3 dogs that underwent gastrotomy (removal of a foreign body in a patient with systematic inflammatory response syndrome), ovariohysterectomy (pregnancy) and pericardiectomy (heart base tumor) respectively. In all dogs, PPV was repeatedly measured during general anesthesia with mechanical ventilation (volume control ventilation, tidal volume 10-12 ml/kg and inspiratory pressure 10-18mmHg) and direct blood pressure measurement, aiming to optimize fluid therapy. In the gastrotomy and pericardiectomy cases, PPV was measured while the patients where hypotensive. In the pregnant bitch in expectation of hypovolemia after uterus removal. PPV measurements in the pericardiectomy case were performed with a “closed” chest both before the thoracotomy and also after a thoracic chest tube was placed and all the amount of air was removed. Administration of fluids (Lactated Ringer’s) was guided by PPV results.
Results
Both the dog that underwent gastrotomy and the pregnant bitch were fluid responders as judged by their initial PPV values (16% and 17% respectively) and their subsequent decrease (8% and 9% respectively) after administration of a large amount of fluids (in the gastrotomy case the arterial blood pressure rose to normal levels). In contrast, the third dog that underwent pericardiectomy surgery, was a non responder since its initial preoperative PPV value was 10% and its subsequent value at the end of surgery was 8.5% receiving a small amount of fluids.
Conclusion
PPV measurement as described helped to optimize fluid administration in these three cases.
References
- Boysen SR and Gommeren K (2021) Assessment of Volume Status and Fluid Responsiveness in Small Animals, Frontiers in Veterinary Science 8(May), pp. 1–23. Available at: https://doi.org/10.3389/fvets.2021.630643.
- Fantoni DT et al. (2017) Pulse pressure variation as a guide for volume expansion in dogs undergoing orthopedic surgery, Veterinary anaesthesia and analgesia, 44(4), pp. 710–718. Available at: https://doi.org/10.1016/J.VAA.2016.11.011.
- Perel A, Pizov R and Cotev S (2014) Respiratory variations in the arterial pressure during mechanical ventilation reflect volume status and fluid responsiveness, 40(6), pp. 798–807. Available at: https://doi.org/10.1007/s00134-014-3285-9.
- Sano H et al. (2018) Evaluation of pulse pressure variation and pleth variability index to predict fluid responsiveness in mechanically ventilated isofluraneanesthetized dogs, Journal of Veterinary Emergency and Critical Care 28(4), pp. 301–309. Available at: https://doi. org/10.1111/vec.12728.
