Influence of drugs on the response characteristics of the LiDCO sensor: an in vitro study.

The research article investigates how certain drugs can affect the accuracy of the lithium dilution cardiac output (LiDCO) sensor measurements. The study found that a variety of drugs can indeed influence the sensor readings, with some causing substantial biases at clinically relevant concentrations.

Methodology

• The authors focused on the influence of several drugs on the LiDCO sensor. Lithium and drugs were dissolved into a saline solution producing different mixtures. These mixtures included saline, saline-lithium, saline-drug, and saline-drug-lithium solutions.
• The drug concentrations overlapped the range of clinical interest based on information obtained from published literature.
• These solutions were warmed to 38°C and pumped through the LiDCO sensor in a set order. The resulting voltage of the sensor was then measured.
• Determined by the differences in voltage changes in the sensor when lithium was present with or without drugs, the authors defined erroneous lithium detections that may cause biases in the LiDCO readings in a live organism.

Results

• Certain drugs, including Clonidine, detomidine, dexmedetomidine, medetomidine, romifidine, xylazine, ketamine, S-ketamine, lidocaine, and rocuronium resulted in concentration-dependent increases in sensor voltages.
• The changes caused by these drugs were equivalent to more than +10% biases in LiDCO.
• Other drugs like atipamezole, acepromazine, butorphanol, diazepam, midazolam, and guaifenesin had minimal or no effect on the sensor reading.
• The changes in voltage induced by drugs were strongly correlated with calculated biases in LiDCO (r(2)=0.91).

Conclusion

• Various drugs affected the accuracy of the LiDCO sensor, but only a few can cause notable biases at clinically important concentrations. These include xylazine, ketamine, lidocaine, and rocuronium.
• These results need to be confirmed in vivo, meaning in an actual organism rather than in a controlled environment.
• The presence of drugs may suggest possible interactions with the LiDCO sensor if they cause significant changes in sensor voltages.