Carbon Dioxide – Induced Anxiety; Effects of Carbon Dioxide on Behavior, Physiology, and Biochemistry in Patients with Panic Disorders and Healthy Subjects.


  • Fazeelat Hajra Karim Khyber Girls Medical College, Peshawar.
  • Muhammad Razaq Jinnah Medical College, Peshawar.
  • Fouzia Qadir North West School of Medicine, Peshawar.
  • Ali Ahsan Mufti Jinnah Medical College, Peshawar.
  • Sikandar Ali Khan Khyber Girls Medical College, Peshawar.



Anxiety, Behavior, Carbon Dioxide, Inhalation, Panic Disorders, Panic Attacks, Sensitivity


Objective: To investigate the processes that make people with panic disorder more vulnerable to the anxiety brought on by exposure to carbon monoxide. Study Design: Randomized, Cross-over Design. Setting: Hayatabad Medical Complex and Khyber Girls Medical College. Period: April 2022 to December 2022. Material & Methods: Patients with anxiety-related conditions and volunteers in good health who underwent CO2 testing were included in the research. Various gas mixtures, including air, 5% CO2, and 7.5% CO2, were administered to participants in a random order. Behavioral measures, physiological parameters, and biochemical markers were assessed during and after CO2 inhalation. Results: Panic episodes were elicited in both patients with panic disorder and healthy controls by inhaling 5% CO2. Panic disorder patients experienced significantly higher anxiety, nervousness, dread, and sadness levels during 5% CO2 inhalation compared to healthy subjects. Physiological effects, such as increased pulse rate, contrasted those with panic disorder with those without it. No significant changes were seen in either group as a result of inhaling CO2 with respect to bloodstream levels of “free 3-methoxy-4-hydroxyphenylglycol, cortisol, growth hormone, or prolactin”. Conclusion: The inhaling of CO2 may trigger panic episodes and cause more intense behavioral and physicological reactions in those with panic disorder.

Author Biographies

Fazeelat Hajra Karim, Khyber Girls Medical College, Peshawar.

MBBS, M.Phil (Physiology), Lecture Physiology, 

Muhammad Razaq, Jinnah Medical College, Peshawar.

MBBS, M.Phil (Biochemistry), Assistant Professor Biochemistry, 

Fouzia Qadir, North West School of Medicine, Peshawar.

MBBS, Master of Science and Molecular Medicine, Associate Professor Biochemistry, 

Ali Ahsan Mufti, Jinnah Medical College, Peshawar.

MBBS, FCPS (Psychiatric) HOD and Associate Professor, 

Sikandar Ali Khan, Khyber Girls Medical College, Peshawar.

MBBS, M.Phil (Biochemistry), Lecturer Biochemistry,