Testing of Cerebral Autoregulation in Head Injury by Waveform Analysis of Blood Flow Velocity and Cerebral Perfusion Pressure

Czosnyka, Marek; Guazzo, E.; Iyer, Vijay; Kirkpatrick, Peter J.; Śmielewski, Piotr; Whitehouse, Helen; Pickard, John D.

doi:10.1007/978-3-7091-9334-1_128

Cited by 28 publications

(23 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An increase in the ICP pulse amplitude in parallel with the mean intracranial pressure can be seen in various clinical situations during continuous ICP monitoring [23] or during CSF infusion tests [6] with an upper breakpoint in the relationship readily observed in individual patients [7,9,11,19,23] (Fig. 1).…”

Section: Upper Breakpoint Of the Amplitude-pressure Curvementioning

confidence: 95%

“…To allow for this, the following parameters were calculated and are presented in Table 3: (i) % of time when ICP was elevated above 20 mmHg, which is accepted by consensus as a limit for post traumatic intracranial hypertension [5]; (ii) % of time when CPP was less than 55 mmHg. This limit was chosen in our group of patients because the previous preliminary study [6] showed disturbed blood supply in transcranial Doppler studies for CPP < 55 mmHg; (iii) % of time when mean ABP was less than 70 mmHg; this limit was chosen as a borderline for systemic hypotension [5]; (iv) % of time when there was close correlation between ICP pulse amplitude and mean ICP (RAP > 0.5); (v) time when RAP was less than 0.5 as a percent of time when ICP was greater than 20 mmHg. …”

Section: Monitored Parameters In Patients With Different Outcomementioning

confidence: 99%

See 1 more Smart Citation

Significance of intracranial pressure waveform analysis after head injury

et al. 1996

Self Cite

View full text Add to dashboard Cite

The authors have investigated the relationships between the amplitude of the ICP pulse wave, the mean values of ICP and CPP, and the outcome of 56 head injured ventilated patients. The ICP was monitored continuously using a Camino transducer (35 patients) or subdural catheter (21 patients). The mean Glasgow Coma Score was 6 (range 3-13; 5 patients had a GCS > 8 after resuscitation). Patients were grouped according to their Glasgow Outcome Score assessed at 12 months after injury. The amplitude of ICP pulse waveform was assessed using the fundamental harmonic of the pulse waveform (AMP) to avoid distortion caused by different frequency responses of the pressure transducers used in the study. Statistical analysis revealed that in patients with fatal outcome the ICP pulse amplitude increased when the mean ICP increased to 25 mmHg and then began to decrease. The upper breakpoint of the AMP-ICP relationship was not present in patients with good/moderate outcome. The moving correlation coefficient between the fundamental harmonic of ICP pulse wave and the mean ICP (RAP: R-symbol of correlation between A-amplitude and P-pressure) was introduced to describe the time-dependent changes in correlation between amplitude and mean ICP. The RAP was significantly lower in patients who died or remained in the vegetative state. In 7 patients who died from uncontrollable intracranial hypertension RAP was oscillating or decreased to 0 or negative values well before brain-stem herniation. The combination of an ICP above 20 mmHg for a period longer than 6 hours with low correlation between the amplitude and pressure (RAP < 0.5) was described as an predictive index of an unfavourable outcome.

show abstract

Section: Upper Breakpoint Of the Amplitude-pressure Curvementioning

confidence: 95%

Section: Monitored Parameters In Patients With Different Outcomementioning

confidence: 99%

Significance of intracranial pressure waveform analysis after head injury

et al. 1996

Self Cite

View full text Add to dashboard Cite

show abstract

“…49 It has also been suggested, at least in patients with head injury, that pulsatile flow requires less energy expenditure to maintain forward flow. 47 At least in the animal model, this compensatory mechanism maintains CBF until further dilation and fall in MCAv diastolic is exhausted; once that point is surpassed, CBF diminishes rapidly. 49 The preferential declines in MCAv diastolic and maintained MCAv systolic are consistent with the changes that occur during profound hypotension at the point of syncope.…”

Section: Differential Changes In Cbf Velocity Pulsatility During Hypomentioning

confidence: 99%

“…10 The same comparison exists with investigators performing linear regression analysis, adopting the correlation coefficient (r) as a measure of CA. 23,47 Although the majority of these studies did not include a healthy age group for comparison, they nevertheless concluded that CA was impaired because of the relatively high correlation coefficient of the MAP versus CBF relationship. The findings of the present study, on the basis of otherwise healthy humans, indicate that neither a high linear regression slope nor a correlation coefficient between alterations in CBF with MAP necessarily imply a defective CA.…”

mentioning

confidence: 99%

Influence of Changes in Blood Pressure on Cerebral Perfusion and Oxygenation

et al. 2010

View full text Add to dashboard Cite

Abstract-Cerebral autoregulation (CA) is a critical process for the maintenance of cerebral blood flow and oxygenation.Assessment of CA is frequently used for experimental research and in the diagnosis, monitoring, or prognosis of cerebrovascular disease; however, despite the extensive use and reference to static CA, a valid quantification of "normal" CA has not been clearly identified. While controlling for the influence of arterial PCO 2 , we provide the first clear examination of static CA in healthy humans over a wide range of blood pressure. In 11 healthy humans, beat-to-beat blood pressure (radial arterial), middle cerebral artery blood velocity (MCAv; transcranial Doppler ultrasound), end-tidal PCO 2 , and cerebral oxygenation (near infrared spectroscopy) were recorded continuously during pharmacological-induced changes in mean blood pressure. In a randomized order, steady-state decreases and increases in mean blood pressure (8 to 14 levels; range: Ϸ40 to Ϸ125 mm Hg) were achieved using intravenous infusions of sodium nitroprusside or phenylephrine, respectively. MCAv mean was altered by 0.82Ϯ0.35% per millimeter of mercury change in mean blood pressure (R 2 ϭ0.82). Changes in cortical oxygenation index were inversely related to changes in mean blood pressure (slopeϭϪ0.18%/mm Hg; R 2 ϭ0.60) and MCAv mean (slopeϭϪ0.26%/cm ⅐ s Ϫ1; R 2 ϭ0.54). There was a progressive increase in MCAv pulsatility with hypotension. These findings indicate that cerebral blood flow closely follows pharmacological-induced changes in blood pressure in otherwise healthy humans. Thus, a finite slope of the plateau region does not necessarily imply a defective CA. Moreover, with progressive hypotension and hypertension there are differential changes in cerebral oxygenation and MCAv mean . (Hypertension. 2010;55:698-705.)

show abstract

“…Several techniques to estimate the autoregulation threshold, both invasive and non-invasive, have been suggested. 18,81 By using jugular venous bulb oximetry and transcranial Doppler sonography the breakpoint was determined to be 70 mmHg. 9 Others have shown a slightly lower threshold (60 mmHg) by brain tissue and jugular bulb oximetry.…”

Section: Cerebral Monitoring (Icp / Cpp)mentioning

confidence: 99%

Current Concepts in Diagnosis and Treatment of Traumatic Brain Injury: Implications for Healthcare in Nepal

Sakowitz

Sharma

Kiening³

2005

Nep J Neurosci

View full text Add to dashboard Cite

Taumatic brain injury (TBI) is a leading cause of disability and death in the industrialized and in the developing world. With an incidence of 200-400 cases per 100.000, head injuries are a major contributor to socio-economic costs. The 20% suffering from severe head injury (SHI) requiring prolonged intensive care and/or neurosurgical intervention are of particular interest to specialist practitioners from multiple disciplines.This review covers the current concepts of diagnosis and treatment in these patients in the Western world, i.e. mainly the US and Western Europe. Special emphasis is laid upon evidence-based guidelines established during the last decade. Comparison is drawn to the current status of trauma care in Nepal.Management strategies for TBI can not be applied to Nepalese healthcare entirely. Effective management of head injured persons in Nepal is affected by its difficult geographical location, unavailability of trained personnel in the field, and difficulty in transporting the patients due to the lack of motorable roads. While some of the equipment for the treatment of TBI victims is readily available (e.g. ventricular drainage), others are scarce (e.g. operating room capacity, intensive care facilities) or completely unavailable (e.g. emergency medical service providers, specialized monitoring equipment). Realistic proposals for improvement of the current situation are made. Nepal Journal of Neuroscience, Volume 2, Number 1, 2005, page: 29-51

show abstract

Testing of Cerebral Autoregulation in Head Injury by Waveform Analysis of Blood Flow Velocity and Cerebral Perfusion Pressure

Cited by 28 publications

References 8 publications

Significance of intracranial pressure waveform analysis after head injury

Significance of intracranial pressure waveform analysis after head injury

Influence of Changes in Blood Pressure on Cerebral Perfusion and Oxygenation

Current Concepts in Diagnosis and Treatment of Traumatic Brain Injury: Implications for Healthcare in Nepal

Contact Info

Product

Resources

About