Heart rate and respiratory response to doxapram in patients with panic disorder

Biochemical challenges for testing novel anti-panic drugs in humans

Current medications for panic disorder each carry significant limitations that indicate the need for novel anxiolytics. The high costs and low success rates of drug development demand that testing trials be efficient. Lab panicogenic challenges in humans allow for the rapid biochemical induction of panic symptoms and hence an efficient means of testing potential anti-panic drugs. This paper describes ideal characteristics of lab panicogens, reviews the validity and utility of various biochemical panicogenic agents, identifies key outcome measures for studies of novel anti-panic drugs, and makes broad recommendations for labs wishing to perform such studies. We conclude by presenting a four-tiered hierarchy of panicogens that matches each against ideal characteristics and reflects our recommendations for their laboratory use.

The effects of doxapram on time to tracheal extubation and early recovery in young morbidly obese patients scheduled for bariatric surgery: A randomised controlled trial

BACKGROUND

Bariatric surgery is a well established treatment of the obese. Postoperative respiratory failure and airway obstruction after bariatric surgery can often be attributed to the residual depressant effects of anaesthetics, sedatives and opioids. Peri-operative management of morbidly obese patients is still a concern for operating room professionals.

OBJECTIVE

The evaluation of the effects of doxapram on the outcomes of general anaesthesia following bariatric surgical procedures in the morbidly obese.

DESIGN

A single-blind randomised controlled trial with two parallel arms.

SETTING

A tertiary care teaching hospital, Tehran, Iran, from 2017 to 2018.

PARTICIPANTS

In total, 100 patients (69 women) with at least class two obesity were included in two groups of equal sizes and underwent bariatric surgery.

MAIN OUTCOME MEASURES

The primary outcome was the time from the administration of doxapram to tracheal extubation. Secondary outcomes included vital signs and variables including peak expiratory flow rate, time to return to spontaneous breathing, time to eye-opening and hand-squeezing on the commands, and time to recovery.

INTERVENTIONS

Both groups underwent general anaesthesia. The intervention group received a single dose of doxapram 1 mg kg ideal body weight, immediately after reversal of neuromuscular blockade and after discontinuation of all anaesthetics.

RESULTS

Doxapram decreased time to extubation, time to eye-opening and hand-squeezing, shortened recovery time and lowered end-tidal CO2 significantly (all P < 0.001). Moreover, it increased peak expiratory flow rate, oxygen saturation, temperature, heart rate and blood pressure (all P < 0.001). The two groups were similar in the bispectral index and mean arterial pressure (both P > 0.05). None of our participants had complications attributable to doxapram.

CONCLUSION

The postoperative use of doxapram improves peak expiratory flow rate, and decreases respiratory complications of anaesthesia during recovery in the morbidly obese undergoing bariatric surgery. Doxapram is well tolerated in young ASA physical status classes 1 to 2 morbidly obese patients; however, the anaesthesiologist should cautiously evaluate the vital signs for at least half an hour following the administration of doxapram.

REGISTRATION

Iranian Registry of Clinical Trials (IRCT) http://www.irct.ir/ number IRCT2017060712203N9.

Intravenous doxapram administration as a potential model of panic attacks in rats

Panic disorder can be categorized into the nonrespiratory or the respiratory subtypes, the latter comprising dyspnea, shortness of breath, chest pain, feelings of suffocation, and paresthesias. Doxapram is an analeptic capable of inducing panic attacks with respiratory symptoms in individuals diagnosed with the disorder; however, its neuroanatomical targets and its effects on experimental animals remain uncharacterized. One of the brain regions proposed to trigger panic attacks is the midbrain periaqueductal gray (PAG). Therefore, in this study, we evaluated the effects of doxapram in Fos (c-Fos) protein expression in the PAG and characterized its cardiorespiratory and behavioral effects on the elevated T maze and in the conditioned place aversion (CPA) paradigms. Doxapram increased Fos expression in different columns of the PAG, increased respiratory frequency, decreased heart rate, and increased arterial pressure when injected via intravenous route. Alprazolam, a panicolytic benzodiazepine, injected via intraperitoneal route, decreased respiratory frequency, whereas URB597, an anandamide hydrolysis inhibitor injected via intraperitoneal route, was ineffective. Doxapram injected via intraperitoneal route induced an anxiogenic-like effect in the elevated T-maze model; however, it failed to induce CPA. This study suggests that the cardiorespiratory and behavioral effects of doxapram in rodents serve as an experimental model that can provide insights into the neurobiology of panic attacks.

Heart rate variability for treatment response between patients with major depressive disorder versus panic disorder: A 12-week follow-up study

BACKGROUND

Heart Rate Variability (HRV) parameters have been used to evaluate the autonomic nervous system. We hypothesized that patients with major depressive disorder (MDD) and panic disorder (PD) showed different HRV profiles compared to healthy controls. We also hypothesized that we could predict the responder groups in the MDD and PD patients, using differences in HRV indices between the stress and rest phases.

METHODS

28 MDD patients and 29 PD patients were followed for 12 weeks, and we also followed 39 healthy control subjects. We measured HRV parameters at the rest, stress, and recovery phases.

RESULTS

Patients with MDD and PD demonstrated lower pNN50 than controls during the stress (F = 7.49, p = 0.001), and recovery phases (F = 9.43, p = 0.0001). Patients with MDD and PD also showed higher LF/HF ratio than controls during the stress phase (F = 6.15, p = 0.002). Responders in the PD group presented a lower level of LF/HF ratio during the stress phase compared to non-responders (F = 10.14, p = 0.002), while responders in the MDD group showed a lower level of heart rate during all three phases, compared to non-responders. Additionally, we could predict treatment response in patients with MDD using ΔLF/HF ratio (OR: 1.33, 95% CI = 1.07-1.65, p = 0.011) and ΔpNN50 (OR: 1.49, 95% CI 1.09-1.77, p = 0.014).

CONCLUSION

The changes of HRV parameters of pNN50 and LF/HF ratio between the stress and recovery phase may be clinical markers of predictors of treatment responsiveness in MDD and PD patients.

Human emotion recognition using heart rate variability analysis with spectral bands based on respiration

The work presented in this paper aims at assessing human emotion recognition by means of the analysis of the heart rate variability (HRV) with varying spectral bands based on respiratory frequency (RF). Three specific emotional states are compared corresponding to calm-neutral state (Relax), positive elicitation (Joy) and negative elicitation (Fear). Standard HRV analysis in time and frequency domain is performed. In order to better characterize the HRV component related to respiratory sinus arrhythmia, the high frequency (HF) band is centered on RF. Results reveal that the power content in low band (PLF), the normalized power content in HF band (PHFn) and the sympathovagal ratio (LF/HF) can be suitable indices to distinguish Relax and Joy. Mean heart rate and RF are significantly different between Relax and Fear. Different HRV indices show significant differences between Joy and Fear, such as pNN50, PLF, PHFn and LF/HF. Statistical analysis of HRV indices with HF centered in the RF results in a lower p-value than the ones with a HF standard band.