Reducing Intracranial Pressure by Reducing Central Venous Pressure: Assessment of potential countermeasures to spaceflight associated neuro-ocular syndrome.

2020 ◽  
Author(s):  
Alexander B. Hansen ◽  
Justin Stevan Lawley ◽  
Caroline A. Rickards ◽  
Erin J. Howden ◽  
Satyam Sarma ◽  
...  
Keyword(s):  
Intracranial Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Free Breathing ◽  
Central Venous ◽  
Supine Posture ◽  
Inspiratory Resistance ◽  
Minimal Reduction ◽  
Clinical Conditions ◽  
Impedance Threshold Device

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Due to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Due to the coupling of central venous (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32±13 yrs) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an Impedance Threshold Device (ITD, -7 cm.H2O) to generate negative intrathoracic pressure for five-mins, and subsequently, wore bilateral thigh cuffs at 30-mmHg for two-mins. Breathing through an ITD reduced both CVP (6±2 vs 3±1 mmHg; P=0.02) and ICP (16±3 vs 12±1 mmHg; P=0.04) compared to the supine posture, which was not observed during the free breathing condition (CVP, 6±2 vs 6±2 mmHg; P=0.87 and ICP, 15±3 vs 15±4 mmHg; P=0.68). Inflation of the thigh cuffs to 30-mmHg caused no meaningful reduction in CVP in all four individuals (5±4 vs 5±4 mmHg; P=0.1), coincident with a minimal reduction in ICP (15±3 vs 14±4 mmHg; P=0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

scholarly journals Senkung des intrakraniellen Drucks durch Senkung des zentralvenösen Drucks: Bewertung möglicher Gegenmaßnahmen zum Raumfahrt-assoziierten neuro-okulären Syndrom

2021 ◽  
pp. 1-2
Author(s):  
Sebastian Siebelmann
Keyword(s):  
Intracranial Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Free Breathing ◽  
Optic Disc Edema ◽  
Threshold Device ◽  
Inspiratory Resistance ◽  
Minimal Reduction ◽  
Clinical Conditions ◽  
Impedance Threshold Device

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, −7 cmH<sub>2</sub>O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; <i>P</i> = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; <i>P</i> = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, <i>P</i> = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, <i>P</i> = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; <i>P</i> = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; <i>P =</i>0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

Effect of positive end expiratory pressure ventilation on intracranial pressure in man

1977 ◽  
Vol 46 (2) ◽  
pp. 227-232 ◽  
Author(s):  
Michael L. J. Apuzzo ◽  
Martin H. Weiss ◽  
Viesturs Petersons ◽  
R. Baldwin Small ◽  
Theodore Kurze ◽  
...  
Keyword(s):  
Intracranial Pressure ◽  
Perfusion Pressure ◽  
Venous Pressure ◽  
Blood Gases ◽  
Pulmonary Injury ◽  
Positive End Expiratory Pressure ◽  
Central Venous ◽  
Content Type ◽  
Arterial Blood ◽  
Peep Ventilation

✓ This study was designed to define the effect of positive end expiratory pressure (PEEP) ventilation on intracranial pressure (ICP). In 25 patients with severe head trauma with and without associated pulmonary injury the following parameters were simultaneously monitored under mechanical ventilation with and without PEEP: ICP, arterial blood pressure, central venous pressure, arterial blood gases, and cardiac rate. In addition, the volume-pressure response (VPR) was evaluated in each patient to assess cerebral elastance. The results indicate a significant increase in ICP with the application of PEEP only in the 12 patients who manifested increased cerebral elastance by VPR. Half of this latter group manifested impairment of cerebral perfusion pressure to levels less than 60 mm Hg. Return to baseline ICP levels was observed with termination of PEEP. No significantly consistent changes in other parameters were noted.

scholarly journals Prospective Study of Central Venous Pressure Trends during Major Neurosurgical Procedures in an Elective Operation Theatre Setting of a Tertiary Care Centre

2021 ◽  
Vol 8 (07) ◽  
pp. 369-373
Author(s):  
Rajeev Damodaran Sarojini ◽  
Sanjay Sahadevan ◽  
Jayakumar Christhudas
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Prospective Study ◽  
Central Venous Pressure ◽  
Inferior Vena ◽  
Venous Pressure ◽  
Ultra Sound ◽  
Neurosurgical Procedures ◽  
Central Venous ◽  
Intraoperative Period

BACKGROUND There are extensive variations in central venous pressure during intraoperative period of a major neurosurgical patients. Monitoring of central venous pressure is vital for guiding the administration of fluids, blood and blood products. Central venous pressure (CVP) also measures the intracranial pressure indirectly. Increased intracranial pressure thereby reduces the cerebral blood flow, leading to cerebral ischemia. METHODS This is a prospective study where 25 major neurosurgical cases posted for elective major neurosurgery were selected. Right subclavian vein was selected for cannulation, by blind technique in all these cases. CVP was recorded every 15 minutes. Central venous catheter was connected to a pressure transducer linked to a multichannel monitor; zeroing was done and the CVP reading obtained. RESULTS Central venous pressure reading was done serially and showed the trends in haemodynamics in various stages of surgery. Initial intraoperative periods showed lower values due to intravenous (I / V) induction of anaesthesia, use of mannitol and diuretics. Later on, the trends changed to higher side subsequent to administration of fluids and blood as required. CONCLUSIONS Monitoring of CVP is an important component of haemodynamic monitoring along with non-invasive blood pressure (NIBP), intra-arterial blood pressure (IABP), and urine output. Central venous pressure can be used to aspirate an air embolism occurring during the intraoperative period after employing Durant’s position. KEYWORDS CVP, NIBP , USS – Ultra Sound Scan, IVC – Inferior Vena Cava, IVCCI – Inferior Vena Cave Collapsibility Index, PEEP – Positive End Expiratory Pressure, C / L – Central Line, IABP.

Divergence of Intracranial and Central Venous Pressures in Lightly Anesthetized, Tracheally Intubated Dogs That Move in Response to a Noxious Stimulus

1996 ◽  
Vol 84 (3) ◽  
pp. 605-613 ◽  
Author(s):  
William L. Lanier ◽  
Ronald F. Albrecht ◽  
Paul A. Iaizzo
Keyword(s):  
Central Venous Pressure ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Superior Vena ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Noxious Stimulus ◽  
Central Venous ◽  
Superior Vena Caval ◽  
The Right

Background Intracranial pressure (ICP) may increase in tracheally intubated subjects during periods of movement (e.g, "bucking" and coughing). Recent research has suggested that factors other than passive congestion of the cerebral vessels, resulting from increases in central venous pressure, may contribute to the ICP response. The current study evaluated this issue in a canine model of intracranial hypertension and additionally evaluated the relationship between ICP and static increases in superior vena caval pressure. Methods Six dogs were lightly anesthetized with 0.65% end-expired halothane in oxygen and nitrogen, and ventilation was mechanically controlled. Intracranial pressure was increased to a stable baseline of 15-20 mmHg using a subarachnoid infusion of warm 0.9% saline solution. The following variables were quantified before, and for 6 min after, initiating a 1-min noxious stimulus to the trachea and skin: ICP, central venous pressure, electromyograms (masseter, deltoid, and intercostal muscles), intrathoracic pressure, and cerebral perfusion pressure (defined as mean arterial pressure -- ICP). Later, the protocol was repeated in the presence of neuromuscular block with pancuronium. Finally, in the same dogs, occlusion of the superior vena cava at its junction with the right atrium was used to increase superior vena caval pressure in 5-mmHg increments, from 5 to 30 mmHG, so that the resulting increases in ICP could be quantified. Results In unparalyzed dogs whose heads were maintained at the level of the right atrium, there was a 22-mmHg increase in ICP at 1 min after initiating the noxious stimulus (P&lt;0.05). The ICP increase was related to electromyogram activation and a 6-mmHg increase in central venous pressure; however, it was not associated with significant increases in intrathoracic pressure or cerebral perfusion pressure. Treatment with pancuronium abolished the electromyographic, ICP, and central venous pressure responses to noxious stimulus. When superior vena caval pressure was statically manipulated, the resulting ICP increase was only one half the magnitude of the superior vena caval pressure increase. After elevating the head 14 cm, the ratio of ICP to superior vena pressure increases was reduced to one third. Conclusions If these results apply to humans, it was concluded that increases in ICP that accompany movement in tracheally intubated patients may arise from two complementary factors: (1) cerebrovascular dilation that correlates with electromyographic activity and is mediated by ascending neural pathways that transmit proprioreceptive information, and (2) passive venous congestion that results from any increase in central venous pressure. The influence of the latter factor can be reduced by elevating the head. (Key words: Blood pressure, venous pressure; mean arterial pressure. Muscle: afferent activity; electromyograms, skeletal. Neuromuscular relaxants: pancuronium.)

scholarly journals Intracranial-to-Central Venous Pressure Gap Predicts the Responsiveness of Intracranial Pressure to PEEP in Patients with Traumatic Brain Injury: a Prospective Cohort Study

2020 ◽  
Author(s):  
Li Hong Peng ◽  
Lin Ying Ning ◽  
Cheng Zhi Hui ◽  
Qu Wei ◽  
Zhang Liu ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Cohort Study ◽  
Brain Injury ◽  
Intracranial Pressure ◽  
Roc Curve ◽  
Prospective Cohort ◽  
Venous Pressure ◽  
Curve Analysis ◽  
Central Venous ◽  
Roc Curve Analysis

Abstract Background: Mechanical ventilation (MV) with positive end-expiratory pressure (PEEP) is commonly applied in patients with severe traumatic brain injury (sTBI). However, the individual responsiveness of intracranial pressure (ICP) to PEEP varies. Thus, identifying an indicator detecting ICP responsiveness to PEEP is of great significance. As central venous pressure (CVP) could act as an intermediary to transduce pressure from PEEP to ICP, we developed a new indicator, PICGap, representing the gap between baseline ICP and baseline CVP. The aim of the current study was to explore the relationship between PICGap and ICP responsiveness to PEEP. Methods: A total of 112 patients with sTBI undergoing MV were enrolled in this prospective cohort study. ICP, CVP, cerebral perfusion pressure (CPP), static compliance of the respiratory system (Cst), and end-tidal carbon dioxide pressure (PetCO2) were recorded at the initial (3 cmH2O) and adjusted (15 cmH2O) levels of PEEP. PICGap was assessed as baseline ICP - baseline CVP (when PEEP=3 cmH2O). The patients were classified into the ICP responder and non-responder groups based on whether ICP increment with PEEP adjusted from 3 cmH2O to 15 cmH2O was greater than 20% of baseline ICP. The above parameters were compared between the two groups, and prediction of ICP responsiveness to PEEP adjustment was evaluated by receiver operating characteristic (ROC) curve analysis. Results: Compared with the non-responder group, the responder group had lower PICGap (1.63±1.33 versus 6.56±2.46 mmHg; p<0.001), lower baseline ICP, and higher baseline CVP. ROC curve analysis suggested that PICGap was a stronger predictive indicator of ICP responsiveness to PEEP (AUC=0.957, 95%CI 0.918-0.996; p<0.001) compared with baseline ICP and baseline CVP, with favorable sensitivity (95.24%, 95%CI 86.91%-98.70%) and specificity (87.6%, 95%CI 75.76%-94.27%), at a cut off value of 2.5 mmHg. Conclusion: The impact of PEEP on ICP depends on the gap between baseline ICP and baseline CVP, i.e. PICGap. In addition, PICGap is a potential predictor of ICP responsiveness to PEEP adjustment in patients with sTBI.

scholarly journals Current understanding of the effects of inspiratory resistance on the interactions between systemic blood pressure, cerebral perfusion, intracranial pressure, and cerebrospinal fluid dynamics

2019 ◽  
Vol 127 (5) ◽  
pp. 1206-1214 ◽  
Author(s):  
Pawel J. Winklewski ◽  
Jacek Wolf ◽  
Marcin Gruszecki ◽  
Magdalena Wszedybyl-Winklewska ◽  
Krzysztof Narkiewicz
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Clinical Medicine ◽  
Respiratory Muscles ◽  
Intrathoracic Pressure ◽  
Brain Perfusion ◽  
Systemic Blood Pressure ◽  
Systemic Blood ◽  
Obstructive Sleep ◽  
Inspiratory Resistance

Negative intrathoracic pressure (nITP) is generated by the respiratory muscles during inspiration to overcome inspiratory resistance, thus enabling lung ventilation. Recently developed noninvasive techniques have made it possible to assess the effects of nITP in real time in several physiological aspects such as systemic blood pressure (BP), intracranial pressure (ICP), and cerebral blood flow (CBF). It has been shown that nITP from 0 to −20 cmH2O elevates BP and diminishes ICP, which facilitates brain perfusion. The effects of nITP from −20 to −40 cmH2O on BP, ICP, and CBF remain largely unrecognized, yet even nITP at −40 cmH2O may facilitate CBF by diminishing ICP. Importantly, nITP from −20 to −40 cmH2O has been documented in adults in commonly encountered obstructive sleep apnea, which justifies research in this area. Recent revelations about interactions between ICP and BP have opened up new fields of research in physiological regulation and the pathophysiology of common diseases, such as hypertension, brain injury, and respiratory disorders. A better understanding of these interactions may translate directly into new therapies in various fields of clinical medicine.

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