Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise

Purpose This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses. Methods Thirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat–stand manoeuvres (SS). Results Compared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (− 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05). Conclusions Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH.

Ritka szisztémás gyógyszer-interakció: timololtartalmú szemcsepp és lerkanidipintabletta együttes alkalmazása során ismétlődően jelentkező syncope

The control and planning of the treatment of hypertensive patients need specific attention. As regards concomitant diseases and treatments, glaucoma and the use of eye drops should be taken into consideration. The ingredients of the administered eye drops get through the nasolacrimal canal and can be absorbed by the nasal mucosa. Because of the lack of enterohepatic ‘first pass’ effect, they can act systemically – like after intravenous administration. This way they can cause systemic side effects. The authors present a case of a patient, too, who was examined and medically checked regularly for years with negative results because of repeated syncope. It became clear only at the Hypertension Centre that the timolol-containing combined eye drops caused the symptoms. The authors draw attention to the fact that in the case of systemic side effects which can be connected to beta-blocking agents (blood pressure fall, bradycardia, breathing disturbance, depression), the role of the eye drops should be taken into consideration. At the same time, the possibility of the systemic drug interactions should not be forgotten either. The interaction with dihydropyridine-type calcium-channel blockers can be of great importance. In these cases, after consultation with an ophthalmologist, the glaucoma treatment with eye drops containing beta-blockers should be modified. Orv Hetil. 2019; 160(8): 309–313.

Oxygen saturation and haemodynamic changes prior to circulatory arrest: Implications for transplantation and resuscitation

Aims To describe the progression of oxygen saturations and blood pressure observations prior to death. Introduction The progression of physiological changes around death is unknown. This has important implications in organ donation and resuscitation. Donated organs have a maximal warm ischaemic threshold. In hypoxic cardiac arrest, an understanding of pre-cardiac arrest physiology is important in prognosticating and will allow earlier identification of terminal states. Methods Data were examined for all regional patients over a two-year period offering organ donation after circulatory death. Frequent observations were taken contemporaneously by the organ donation nurse at the time of and after withdrawal of intensive care. Results In all, 82 case notes were examined of patients aged 0 to 76 (median 52, 4 < 18 years). From withdrawal of intensive care to death took a mean of 28.5 min (range 4 to 185). A terminal deterioration in saturations (from an already low baseline) commenced 14 min prior to circulatory arrest, followed by a blood pressure fall commencing 8 min prior to circulatory arrest, and finally a rapid fall in heart rate commencing 4 min prior to circulatory arrest. Two patients had a warm ischaemic time of greater than 30 min; 15 patients had a warm ischaemia time of 10 min or greater; and 53 patients had a warm ischaemia time of 5 min or less. It was observed that 0/82 patients had saturations of less than 40% for more than 3 min prior to cardiac arrest and 74/82 for more than 2 min. Conclusions There is a perimortem sequence of hypoxia, then hypotension, and then bradycardia. The heart is extremely resistant to hypoxia. A warm ischaemic time of over 30 min is rare.