ABSTRACT
OBJECTIVE: To determine if increasing variability of blood pressure influences determination of cerebral autoregulation. METHODS: A prospective observational study was performed at the ICU of a university hospital in the Netherlands. 13 comatose patients after cardiac arrest underwent baseline and intervention (tilting of bed) measurements. Mean flow velocity (MFV) in the middle cerebral artery and mean arterial pressure (MAP) were measured. Coefficient of variation (CV) was used as a standardized measure of dispersion in the time domain. In the frequency domain, coherence, gain, and phase were calculated in the very low and low frequency bands. RESULTS: The CV of MAP was significantly higher during intervention compared to baseline. On individual level, coherence in the VLF band changed in 5 of 21 measurements from unreliable to reliable and in 6 of 21 measurements from reliable to unreliable. In the LF band 1 of 21 measurements changed from unreliable to reliable and 3 of 21 measurements from reliable to unreliable. Gain in the VLF and LF band was lower during intervention compared to baseline. CONCLUSIONS: For the ICU setting, more attention should be paid to the exact experimental protocol, since changes in experimental settings strongly influence results of estimation of cerebral autoregulation.
Subject(s)
Blood Pressure , Cerebrovascular Circulation , Heart Arrest/physiopathology , Homeostasis , Aged , Blood Flow Velocity , Female , Humans , Male , Middle Aged , Netherlands , Prospective StudiesABSTRACT
Out of hospital cardiac arrest is the leading cause of death in industrialized countries. Recovery of hemodynamics does not necessarily lead to recovery of cerebral perfusion. The neurological injury induced by a circulatory arrest mainly determines the prognosis of patients after cardiac arrest and rates of survival with a favourable neurological outcome are low. This review focuses on the temporal course of cerebral perfusion and changes in cerebral autoregulation after out of hospital cardiac arrest. In the early phase after cardiac arrest, patients have a low cerebral blood flow that gradually restores towards normal values during the first 72 hours after cardiac arrest. Whether modification of the cerebral blood flow after return of spontaneous circulation impacts patient outcome remains to be determined.
Subject(s)
Brain/physiopathology , Homeostasis/physiology , Out-of-Hospital Cardiac Arrest/complications , Out-of-Hospital Cardiac Arrest/physiopathology , Animals , Cerebrovascular Circulation/physiology , Hemodynamics/physiology , Humans , Perfusion/methodsABSTRACT
OBJECTIVE: To investigate spontaneous variability in the time and frequency domain in mean flow velocity (MFV) and mean arterial pressure (MAP) in comatose patients after cardiac arrest, and determine possible differences between survivors and non-survivors. METHODS: A prospective observational study was performed at the ICU of a tertiary care university hospital in the Netherlands. We studied 11 comatose patients and 10 controls. MFV in the middle cerebral artery was measured with simultaneously recording of MAP. Coefficient of variation (CV) was used as a standardized measure of dispersion in the time domain. In the frequency domain, the average spectral power of MAP and MFV were calculated in the very low, low and high frequency bands. RESULTS: In survivors CV of MFV increased from 4.66 [3.92-6.28] to 7.52 [5.52-15.23] % at T=72h. In non-survivors CV of MFV decreased from 9.02 [1.70-9.36] to 1.97 [1.97-1.97] %. CV of MAP was low immediately after admission (1.46 [1.09-2.25] %) and remained low at 72h (3.05 [1.87-3.63] %) (p=0.13). There were no differences in CV of MAP between survivors and non-survivors (p=0.30). We noticed significant differences between survivors and non-survivors in the VLF band for average spectral power of MAP (p=0.03) and MFV (p=0.003), whereby the power of both MAP and MFV increased in survivors during admission, while remaining low in non-survivors. CONCLUSIONS: Cerebral blood flow is altered after cardiac arrest, with decreased spontaneous fluctuations in non-survivors. Most likely, these changes are the consequence of impaired intrinsic myogenic vascular function and autonomic dysregulation.
Subject(s)
Blood Flow Velocity/physiology , Cerebrovascular Circulation/physiology , Out-of-Hospital Cardiac Arrest/mortality , Arterial Pressure , Coma/physiopathology , Female , Humans , Male , Out-of-Hospital Cardiac Arrest/physiopathology , Prospective StudiesABSTRACT
The fact that corticosteroids, phenothiazines and myotics induce cataract is well known. Moreover some informations about lens opacities have been reported less frequently after the use of cytostatics, deferoxamine, phenytoine, isotretinoine, oral contraceptives, allopurinol, synthetics antimalarial agents, diazepam, tetracyclines and sulfamides. Occasionally some others drugs have been suspected from experimental observations to produce cataract. Amongst all these drugs, corticosteroids are the most often incriminated.
Subject(s)
Cataract/chemically induced , Adrenal Cortex Hormones/adverse effects , Anti-Arrhythmia Agents/adverse effects , Anti-Bacterial Agents/adverse effects , Antineoplastic Agents/adverse effects , Contraceptives, Oral/adverse effects , Diuretics/adverse effects , Humans , Miotics/adverse effects , Phenothiazines/adverse effectsABSTRACT
The frequency of infectious complications after corneal surgery depend on the type of surgery: after trauma and perforations, corneal graft and perforations, and thus the previous status of the eye, surgical care and patient follow-up.
