The internal jugular vein valve may have a significant role in the prevention of venous reflux: evidence from live and cadaveric human subjects

Jugular venous flow dynamics during acute weightlessness

During spaceflight, fluids shift headward, causing internal jugular vein (IJV) distension and altered hemodynamics, including stasis and retrograde flow, that may increase the risk of thrombosis. This study's purpose was to determine the effects of acute exposure to weightlessness (0-G) on IJV dimensions and flow dynamics. We used two-dimensional (2-D) ultrasound to measure IJV cross-sectional area (CSA) and Doppler ultrasound to characterize venous blood flow patterns in the right and left IJV in 13 healthy participants (6 females) while 1) seated and supine on the ground, 2) supine during 0-G parabolic flight, and 3) supine during level flight (at 1-G). On Earth, in 1-G, moving from seated to supine posture increased CSA in both left (+62 [95% CI: +42 to 81] mm2, P < 0.0001) and right (+86 [95% CI: +58 to 113] mm2, P < 0.00012) IJV. Entry into 0-G further increased IJV CSA in both left (+27 [95% CI: +5 to 48] mm2, P = 0.02) and right (+30 [95% CI: +0.3 to 61] mm2, P = 0.02) relative to supine in 1-G. We observed stagnant flow in the left IJV of one participant during 0-G parabolic flight that remained during level flight but was not present during any imaging during preflight measures in the seated or supine postures; normal venous flow patterns were observed in the right IJV during all conditions in all participants. Alterations to cerebral outflow dynamics in the left IJV can occur during acute exposure to weightlessness and thus, may increase the risk of venous thrombosis during any duration of spaceflight.NEW & NOTEWORTHY The absence of hydrostatic pressure gradients in the vascular system and loss of tissue weight during weightlessness results in altered flow dynamics in the left internal jugular vein in some astronauts that may contribute to an increased risk of thromboembolism during spaceflight. Here, we report that the internal jugular veins distend bilaterally in healthy participants and that flow stasis can occur in the left internal jugular vein during acute weightlessness produced by parabolic flight.

Fetal head-down posture may explain the rapid brain evolution in humans and other primates: An interpretative review

Evolutionary cerebrovascular consequences of upside-down postural verticality of the anthropoid fetus have been largely overlooked in the literature. This working hypothesis-based report provides a literature interpretation from an aspect that the rapid evolution of the human brain has been promoted by fetal head-down position due to maternal upright and semi-upright posture. Habitual vertical torso posture is a feature not only of humans, but also of monkeys and non-human apes that spend considerable time in a sitting position. Consequently, the head-down position of the fetus may have caused physiological craniovascular hypertension that stimulated expansion of the intracranial vessels and acted as an epigenetic physiological stress, which enhanced neurogenesis and eventually, along with other selective pressures, led to the progressive growth of the anthropoid brain and its organization. This article collaterally opens a new insight into the conundrum of high cephalopelvic proportions (i.e., the tight fit between the pelvic birth canal and fetal head) in phylogenetically distant lineages of monkeys, lesser apes, and humans. Low cephalopelvic proportions in non-human great apes could be accounted for by their energetically efficient horizontal nest-sleeping and consequently by their larger body mass compared to monkeys and lesser apes that sleep upright. One can further hypothesize that brain size varies in anthropoids according to the degree of exposure of the fetus to postural verticality. The supporting evidence for this postulation includes a finding that in fossil hominins cerebral blood flow rate increased faster than brain volume. This testable hypothesis opens a perspective for research on fetal postural cerebral hemodynamics.

Surveillance for jugular venous thrombosis in astronauts

BACKGROUND

Thrombosis of the left internal jugular vein in an astronaut aboard the International Space Station was recently described, incidentally discovered during a research study of blood flow in neck veins in microgravity. Given this event, and the high incidence of flow abnormalities, the National Aeronautics and Space Administration (NASA) instituted an occupational surveillance program to evaluate astronauts for venous thrombosis.

METHODS

Duplex ultrasound of the bilateral internal jugular veins was conducted on all NASA astronauts terrestrially, and at three points during spaceflight. Respiratory maneuvers were performed. Images were analyzed for thrombosis and certain hemodynamic characteristics, including peak velocity and degree of echogenicity.

RESULTS

Eleven astronauts were evaluated with matching terrestrial and in-flight ultrasounds. No thrombosis was detected. Compared to terrestrial ultrasound measurements, in-flight peak velocity was reduced and lowest in the left. Six of 11 astronauts had mild-moderate echogenicity in the left internal jugular vein during spaceflight, but none had more than mild echogenicity in the right internal jugular vein. Two astronauts developed retrograde blood flow in the left internal jugular vein.

CONCLUSIONS

Abnormal flow characteristics in microgravity, most prominent in the left internal jugular vein, may signal an increased risk for thrombus formation in some individuals.

Central Venous Obstruction-Induced Intracranial Hypertension in Hemodialysis Patients: An Underrecognized Cause of Elevated Intracranial Pressure

BACKGROUND

Central venous obstruction (stenosis or occlusion) is common in patients with renal failure on hemodialysis and may be associated with intracranial hypertension (IH). Causes include vein injury from an endoluminal device, lumen obstruction from a device or thrombus, external vein compression, and high venous flow leading to vein intimal hyperplasia. A combination of high venous flow and central venous obstruction can lead to intracranial venous hypertension, impaired cerebrospinal fluid (CSF) resorption, and subsequent IH.

EVIDENCE ACQUISITION

We conducted a search of the English literature using the Ovid MEDLINE Database and PubMed, with a focus on reports involving IH and central venous obstruction in the setting of hemodialysis. We reviewed CSF flow dynamics, the risk factors and causes of central venous obstruction, and the evaluation, management, and outcomes of central venous obstruction-induced IH.

RESULTS

Twenty-four cases of IH related to central venous obstruction in hemodialysis patients were identified. Twenty patients had headaches (83.3%) and 9 had visual symptoms (37.5%). The brachiocephalic vein was the most common site of stenosis or occlusion (20/24, 83.3%). Twenty-one patients (87.5%) had resolution of IH with treatment. Two patients died from complications of IH (8.3%).

CONCLUSIONS

Central venous obstruction-induced IH is likely underrecognized by clinicians and mimics idiopathic IH. Hemodialysis patients with IH should be screened with computed tomography venography of the chest. Optimal treatment is with vascular intervention or a CSF diversion procedure and can help prevent vision loss from papilledema or nervous system damage. Medical management may be appropriate in mild cases or as a bridge to definitive interventional treatment. Increased awareness among clinicians has potential to facilitate the timely diagnosis of this treatable condition with potential for good neurologic and visual outcomes.

Dynamic assessment of venous anatomy and function in neurosurgery with real-time intraoperative multimodal ultrasound: technical note

The relevance of the cerebral venous system is often underestimated during neurosurgical procedures. Damage to this draining system can have catastrophic implications for the patient. Surgical decision-making and planning must consider each component of the venous compartment, from the medullary draining vein to the dural sinuses and extracranial veins. Intraoperative ultrasound (ioUS) permits the real-time study of venous compartments using different modalities, thus allowing complete characterization of their anatomical and functional features. The B-mode (brightness mode) offers a high-resolution anatomical representation of veins and their relationships with lesions. Doppler modalities (color, power, spectral) allow the study of blood flow and identification of vessels to distinguish their functional characteristics. Contrast-enhanced US allows one to perform real-time angiosonography showing both the functional and the anatomical aspects of vessels. In this technical report, the authors demonstrate the different applications of multimodal ioUS in neurosurgery for identifying the anatomical and functional characteristics of the venous compartment. They discuss the general principles and technical nuances of ioUS and analyze their potential implications for the study of various venous districts during neurosurgical procedures.

Multiple Sclerosis - A Vascular Etiology?

From the earliest pathological studies the perivenular localization of the demyelination in multiple sclerosis (MS) has been observed. It has recently been suggested that obstructions to venous flow or inadequate venous valves in the great veins in the neck, thorax and abdomen can cause damaging backflow into the cerebral and spinal cord circulations. Paolo Zamboni and colleagues have demonstrated abnormal venous circulation in some multiple sclerosis patients using non-invasive sonography and invasive venography. Furthermore, they have obtained apparent clinical improvement or stabilization by endovascular ballooning of points of obstruction in the great veins in some, at least temporarily. If non-invasive observations by others validate their initial observations of a significantly increased prevalence of venous obstructions in MS then trials of angioplasty/stenting would be justified in selected cases in view of the biological plausibility of the concept.

Prevalence and impact of incompetence of internal jugular valve on postoperative cognitive dysfunction in elderly patients undergoing robot-assisted laparoscopic radical prostatectomy

Internal jugular vein (IJV) is the main pathway of cerebral venous drainage and its valves prevent regurgitation of blood to the brain. IJV valve incompetence (IJVVI) is known to be associated with cerebral dysfunctions. It occurs more often in male over 50 years old, conditions elevating intra-abdominal or intra-thoracic pressure. In robot-assisted laparoscopic radical prostatectomy (RALRP), elderly male undergoes surgery in Trendelenburg position with pneumoperitoneum applied. Therefore, we assessed the IJVVI during RALRP and its influence on postoperative cognitive function. 57 patients undergoing RALRP were enrolled. Neurocognitive tests including Mini-Mental State Examination (MMSE), Auditory Verbal Learning Test, Digit Symbol Substitution Test, Color Word Stroop Test, digit span test, and grooved pegboard test were performed the day before and 2 days after surgery. During surgery, IJVVI was assessed with ultrasonography in supine position with and without pneumoperitoneum, and Trendelenburg position with pneumoperitoneum. 50 patients underwent sonographic assessment and 41 patients completed neurocognitive examination. A total of 27 patients presented IJVVI, 19 patients in supine position without pneumoperitoneum, 7 patients in supine position with pneumoperitoneum and 1 patient in Trendelenburg position with pneumoperitoneum. In neurocognitive tests, patients with IJVVI showed statistically significant decline of score in MMSE postoperatively (p<0.05). IJVVI occurred in 38% in supine position but the incidence was increased to 54% after Trendelenburg position and pneumoperitoneum. Patients with IJVVI did not show significant differences in cognitive function tests except MMSE. Clinical and neurological significance of physiologic changes associated RALRP should be studied further.

Potential involvement of the extracranial venous system in central nervous system disorders and aging

BACKGROUND

The role of the extracranial venous system in the pathology of central nervous system (CNS) disorders and aging is largely unknown. It is acknowledged that the development of the venous system is subject to many variations and that these variations do not necessarily represent pathological findings. The idea has been changing with regards to the extracranial venous system.

DISCUSSION

A range of extracranial venous abnormalities have recently been reported, which could be classified as structural/morphological, hemodynamic/functional and those determined only by the composite criteria and use of multimodal imaging. The presence of these abnormalities usually disrupts normal blood flow and is associated with the development of prominent collateral circulation. The etiology of these abnormalities may be related to embryologic developmental arrest, aging or other comorbidities. Several CNS disorders have been linked to the presence and severity of jugular venous reflux. Another composite criteria-based vascular condition named chronic cerebrospinal venous insufficiency (CCSVI) was recently introduced. CCSVI is characterized by abnormalities of the main extracranial cerebrospinal venous outflow routes that may interfere with normal venous outflow.

SUMMARY

Additional research is needed to better define the role of the extracranial venous system in relation to CNS disorders and aging. The use of endovascular treatment for the correction of these extracranial venous abnormalities should be discouraged, until potential benefit is demonstrated in properly-designed, blinded, randomized and controlled clinical trials.

Internal jugular venous abnormalities in transient monocular blindness

Background

The etiology of transient monocular blindness (TMB) in patients without carotid stenosis has been linked to ocular venous hypertension, for their increased retrobulbar vascular resistance, sustained retinal venule dilatation and higher frequency of jugular venous reflux (JVR). This study aimed to elucidate whether there are anatomical abnormalities at internal jugular vein (IJV) in TMB patients that would contribute to impaired cerebral venous drainage and consequent ocular venous hypertension.

Methods

Contrast-enhanced axial T1-weighted magnetic resonance imaging (MRI) was performed in 23 TMB patients who had no carotid stenosis and 23 age- and sex-matched controls. The veins were assessed at the upper IJV (at C1–3 level) and the middle IJV (at C3–5 level). Grading of IJV compression/stenosis was determined bilaterally as follows: 0 = normal round or ovoid appearance; 1 = mild flattening; 2 = moderate flattening; and 3 = severe flattening or not visualized.

Results

There was significantly more moderate or severe IJV compression/stenosis in the TMB patients at the left upper IJV level and the bilateral middle IJV level. Defining venous compression/stenosis scores ≥ 2 as a significant cerebral venous outflow impairment, TMB patients were found to have higher frequency of significant venous outflow impairment at the upper IJV level (56.5% vs. 8.7%, p = 0.0005) and the middle IJV level (69.6% vs. 21.7%, p=0.0011).

Conclusions

TMB Patients with the absence of carotid stenosis had higher frequency and greater severity of IJV compression/stenosis which could impair cerebral venous outflow. Our results provide evidence supporting that the cerebral venous outflow abnormality is one of the etiologies of TMB.

Neurological sequelae from brachiocephalic vein stenosis

Stenosis of central veins (brachiocephalic vein [BCV] and superior vena cava) occurs in 30% of hemodialysis patients, rarely producing intracranial pathology. The authors present the first cases of BCV stenosis causing perimesencephalic subarachnoid hemorrhage and myoclonic epilepsy.

In the first case, a 73-year-old man on hemodialysis presented with headache and blurry vision, and was admitted with presumed idiopathic intracranial hypertension after negative CT studies and confirmatory lumbar puncture. The patient mildly improved until hospital Day 3, when he experienced a seizure; emergency CT scans showed perimesencephalic subarachnoid hemorrhage. Cerebral angiography failed to find any vascular abnormality, but demonstrated venous congestion. A fistulogram found left BCV occlusion with jugular reflux. The occlusion could not be reopened percutaneously and required open fistula ligation. Postoperatively, symptoms resolved and the patient remained intact at 7-month follow-up.

In the second case, a 67-year-old woman on hemodialysis presented with right arm weakness and myoclonic jerks. Admission MRI revealed subcortical edema and a possible dural arteriovenous fistula. Cerebral angiography showed venous engorgement, but no vascular malformation. A fistulogram found left BCV stenosis with jugular reflux, which was immediately reversed with angioplasty and stent placement. Postprocedure the patient was seizure free, and her strength improved. Seven months later the patient presented in myoclonic status epilepticus, and a fistulogram revealed stent occlusion. Angioplasty successfully reopened the stent and she returned to baseline; she was seizure free at 4-month follow-up.

Central venous stenosis is common with hemodialysis, but rarely presents with neurological findings. Prompt recognition and endovascular intervention can restore normal venous drainage and resolve symptoms.

A technical approach to dissecting and assessing cadaveric veins pertinent to chronic cerebrospinal venous insufficiency in multiple sclerosis

Objective: To establish a detailed technical procedure for studying the anatomical correlates of chronic cerebrospinal venous insufficiency in cadavers of multiple sclerosis and control subjects, and to present our findings of the normal anatomic venous structures, with reference to previous descriptions from the literature.

Methods: This study examined the internal jugular veins (IJVs), the brachiocephalic veins, and the azygos vein from 20 cadavers (10 control and 10 multiple sclerosis). These veins were exposed, isolated by clamps from the rest of the venous system, flushed with water, and then injected with fluid silicone from the superior ends of both IJVs. After the silicone cured to its solid state, the venous tree was removed en bloc and dissected longitudinally to expose the luminal surface. All vein segments were analyzed for anatomic variation. Anatomical analysis for this manuscript focused on normal vein architecture and its variants.

Results: Thirty-seven of 40 IJVs contained valves: 29 bicuspid, 6 tricuspid, and 2 unicuspid. The average circumferences of the right and left IJVs were 2·2 and 1·8 cm, respectively. Thirteen of 20 azygos veins contained a valve, located on average 3·6 cm away from the superior vena cava junction. Nine of the 13 azygos valves were bicuspid; four were tricuspid. Only one of the 40 brachiocephalic veins contained a valve.

Discussion: We detailed a technical approach for harvesting cadaveric neck and thoracic veins with relevance to chronic cerebrospinal venous insufficiency. The anatomy of the venous system has significant variability, including differing number of valves in different regions and variable characteristics of the valves. Average vein circumference was less than that typically reported in imaging studies of live patients.

Heart disease, overweight, and cigarette smoking are associated with increased prevalence of extra-cranial venous abnormalities

OBJECTIVES

Most of the extra-cranial venous abnormalities have been previously described as truncular venous malformations. In this hypothesis-driven study, we evaluated possible association of risk/protective factors with the presence of truncular and functional venous abnormalities in internal jugular veins (IJVs) in a large cohort of volunteers without known central nervous system (CNS) pathology.

METHODS

The study included 240 controls who underwent physical and Doppler sonography (DS) examinations for the presence of intra- and extra-luminal structural and functional abnormalities of the IJVs, and were assessed with a physical examination and structured environmental questionnaire for demographic characteristics, presence of autoimmune and other concomitant diseases, vascular risk factors, environmental factors, and habits. Logistic regression analysis was used to test which risk/protective factors were associated with the presence and number of extra-cranial venous abnormalities.

RESULTS

Subjects with heart disease (P<0·001), overweight (P = 0·005), and smoking (P = 0·016) had a significantly increased number of intra-luminal structural venous abnormalities. Presence of heart disease increased the risk of a malformed valve 12·9 times (95% CI: 5·4-31·3, P<0·001), while smoking increased it 2·21 times (95% CI: 1-4·9, P = 0·033). Being overweight (P = 0·003), a history of mononucleosis (P = 0·012) and smoking (P = 0·042) increased risk for presence of a flap. No association was found between the investigated risk factors and extra-luminal or functional venous abnormalities. However, use of dietary and herbal supplements had a protective role for the presence of functional venous abnormalities.

CONCLUSIONS

There is a close association between intra-luminal, structural, extra-cranial, venous system pathology and the presence of heart disease, overweight, and smoking.

Jugular venous reflux and plasma endothelin-1 are associated with cough syncope: a case control pilot study

Background

Jugular venous reflux (JVR) has been reported to cause cough syncope via retrograde-transmitted venous hypertension and consequently decreased cerebral blood flow (CBF). Unmatched frequencies of JVR and cough syncope led us to postulate that there should be additional factors combined with JVR to exaggerate CBF decrement during cough, leading to syncope. The present pilot study tested the hypothesis that JVR, in addition to an increased level of plasma endothelin-1 (ET-1), a potent vasoconstrictor, is involved in the pathophysiology of cough syncope.

Methods

Seventeen patients with cough syncope or pre-syncope (Mean[SD] = 74.63(12.37) years; 15 males) and 51 age/gender-matched controls received color-coded duplex ultrasonography for JVR determination and plasma ET-1 level measurements.

Results

Multivariate logistic analysis showed that the presence of both-side JVR (odds ratio [OR] = 10.77, 95% confident interval [CI] = 2.40-48.35, p = 0.0019) and plasma ET-1 > 3.43 pg/ml (OR = 14.57, 95% CI = 2.95-71.59, p = 0.001) were independently associated with the presence of cough syncope/ pre-syncope respectively. There was less incidence of cough syncope/ pre-syncope in subjects with the absence of both-side JVR and a plasma ET-1 ≦3.43 pg/ml. Presence of both side JVR and plasma ET-1 level of > 3.43 pg/ml, increased risk for cough syncope/pre-syncope (p < 0.001).

Conclusions

JVR and higher plasma levels of ET-1 are associated with cough syncope/ pre-syncope. Although sample size of this study was small, we showed a synergistic effect between JVR and plasma ET-1 levels on the occurrence of cough syncope/pre-syncope. Future studies should confirm our pilot findings.

Endovascular therapy for chronic cerebrospinal venous insufficiency in multiple sclerosis

Recent reports have emerged suggesting that multiple sclerosis (MS) may be due to abnormal venous outflow from the central nervous system, termed chronic cerebrospinal venous insufficiency (CCSVI). These reports have generated strong interest and controversy over the prospect of a treatable cause of this chronic debilitating disease. This review aims to describe the proposed association between CCSVI and MS, summarize the current data, and discuss the role of endovascular therapy and the need for rigorous randomized clinical trials to evaluate this association and treatment.

Extracranial venous stenosis is an unlikely cause of multiple sclerosis

Background: Extracranial venous stenosis (EVS) has recently been implicated as the primary cause of multiple sclerosis (MS).

Objective: The aim of this study was to determine the presence of EVS in MS patients.

Methods: We performed selective extracranial venography on 42 patients with early MS (EMS): clinically isolated syndrome (CIS) or relapsing—remitting MS (RRMS) of less than 5 years duration, and late MS (LMS): RRMS of more than 10 years duration. Magnetic resonance imaging (MRI) and clinical relapse data were reviewed for all patients with EVS.

Results: EVS was present in 7/29 patients with EMS and 12/13 patients with LMS, a highly significant statistical difference ( p< 0.001). Only 3/42 patients (all in the LMS group) had two vessel stenoses, while the rest had only one vessel involved. EVS was seen in 1/11 patients with CIS compared with 6/18 RRMS patients of less than 5 years duration. Disease duration was greater in patients with EVS overall ( p < 0.005). LMS remained an independent predictor of EVS following multivariate adjustment for gender, age at disease onset and Expanded Disability Status Scale (EDSS) (Adjusted Odds Ratio = 29 (3—298); p = 0.005]. Within the EMS group, patients with ( n = 7) and without ( n = 22) EVS had similar EDSS and disease duration, suggesting similar disease severity. No clear correlation could be found between site of EVS and anatomic localization of either clinical relapses or MRI gadolinium-enhancing lesions.

Conclusions: We conclude that EVS is an unlikely cause of MS since it is not present in most patients early in the disease and rarely involves more than one extracranial vein. It is likely to be a late secondary phenomenon.

Jugular venous hemodynamic changes with aging

Cerebral venous outflow insufficiency via the internal jugular vein (IJV) is associated with several neurological disorders. However, a normal reference set of IJV hemodynamic parameters derived from a large, healthy population over a wide range of age has, until now, been lacking. Color-coded duplex sonography was performed on the IJVs of 349 subjects (55.60 ± 17.49,16 to 89 y; 167 M/182 F). With increasing age, increased lumen area and decreased time-averaged mean velocity of bilateral IJV and a decreased proportion of total flow volume, drainage in the left IJV were found. The frequency of left jugular venous reflux (JVR) also increased with aging. We report IJV hemodynamic parameters across a large population, which could be used as a normal reference for clinical and research purposes. Furthermore, we found a decreased proportion of venous drainage, increased JVR prevalence, dilated lumen and slowed flow velocity in the left IJV, all of which suggest increased left IJV outflow impedance with aging.

Resuscitation and conjunctival petechial hemorrhages

In recent years, cardiopulmonary resuscitation (CPR) has been discussed as a cause of petechial hemorrhage in eyelids and conjunctivae, which could be of substantial significance to forensic expertises in cases of suspected strangulation. In the reported series or case observations, the combination of CPR and petechiae seemed to be sufficient to explain such a causal connection. Nearly all presented cases were victims for which the mechanisms resulting in death were themselves well-known causes explaining the development of such petechiae; and said mechanisms can frequently be observed in victims that did not receive CPR. An earlier, also retrospective, analysis of a series of forensic autopsies did not confirm CPR as a significant cause of conjunctival petechiae. Now we present the result of a prospective examination of 196 resuscitations of adult patients with separate assessment of petechiae being present even prior to resuscitation. Petechiae were present in 12 cases - but in eight of them prior to resuscitation already. Three other persons with petechiae found only after CPR were in the group of successfully resuscitated persons and exhibited petechiae hours after CPR during therapy in intensive care units - during a phase of ongoing cardiac insufficiency, which obviously caused them. The only case with petechiae observed neither immediately prior to nor after unsuccessful resuscitation, but during a follow-up examination one day later, needs to be discussed. It is not interpreted as reliable evidence for the causality of CPR though. Our interpretation of reports in literature as well as our experiences confirm the absence of actual proof of petechiae being generated by CPR and in the presence of generally significant doubts of this relation.

Internal jugular vein valve incompetence in COPD and primary pulmonary hypertension

PURPOSE

Under physiologic conditions, intact internal jugular vein valves (IJVVs) efficiently prevent retrograde venous flow during intrathoracic pressure increase. Chronically elevated central venous pressure found in patients with chronic obstructive pulmonary disease (COPD) and primary pulmonary hypertension (PPH) might lead to IJVV incompetence (IJVVI). The aim of this study was to analyze the prevalence of IJVVI in patients with COPD and PPH using duplex sonography (DUS).

METHOD

We included 30 COPD patients, 5 PPH patients, and 100 healthy controls in the study. IJVVI was diagnosed if retrograde jugular blood flow was seen on DUS during a Valsalva maneuver. Retrograde venous flow intensity was evaluated and graded according to extent and duration of reflux.

RESULTS

IJVVI was found in 18 (60%) COPD patients and in all 5 (100%) PPH patients, which was significantly different from the controls (27%; p < 0.005). The intensity of venous retrograde flow correlated with the pulmonary artery pressure.

CONCLUSION

Compared with healthy controls, COPDand PPH patients demonstrated a significantlygreater prevalence of IJVVI, which seems to be caused by the elevated central venous pressure. These patients may be at higher risk to develop central nervous system diseases related to cerebral outflow obstruction.

Flow volume in the jugular vein and related hemodynamics in the branches of the jugular vein

Venous reflux in the internal jugular vein branches (JB) was found frequently in patients of certain neurologic disorders. We hypothesized that the retrograde-flow in JB is associated with retrograde hypertension transmitted from the internal jugular vein (IJV), which presumably underlies those neurologic disorders. In this study, we used color-Doppler imaging to evaluate the dynamic venous flow patterns in the IJV and its branches in 50 normal individuals (21 men, 29 women; mean age: 40.9 +/- 14.9 y, range: 22 to 70 y). The flow-direction of all detected JB (n = 100) was flowing into the IJV at baseline. During the Valsalva maneuver (VM), 38 JB (38%) had a retrograde-flow. Retrograde-flow in JB was significantly associated with IJV valve incompetence (OR = 7.6; 95% CI = 2.6 to 21.8; p = 0.0002) and greater IJV blood flow volume (blood flow volume >670 mL/min) (OR = 6.6; 95% CI = 1.8 to 24.5; p = 0.0052), both of which may reflect higher IJV pressure transmission during VM. The sonographic findings can be used in the future studies of diseases that are suspected to be related with retrograde cerebral venous hypertension due to an elevated IJV venous pressure.

Incompetence of the Internal Jugular Venous Valve: Spectrum of Echo-Doppler Appearances

The echocardiographic literature contains very scant reference to incompetence of the valve in the internal jugular vein. However, we found frequent Doppler evidence of such incompetence, especially in patients with congestive failure. This incompetence manifests as a variety of color Doppler and pulsed Doppler patterns, illustrated here in 3 patients.

Effects of incomplete chest wall decompression during cardiopulmonary resuscitation on coronary and cerebral perfusion pressures in a porcine model of cardiac arrest

INTRODUCTION

Recent data suggest that generation of negative intrathoracic pressure during the decompression phase of CPR improves hemodynamics, organ perfusion and survival.

HYPOTHESIS

Incomplete chest wall recoil during the decompression phase of standard CPR increases intrathoracic pressure and right atrial pressure, impedes venous return, decreases compression-induced aortic pressures and results in a decrease of mean arterial pressure, coronary and cerebral perfusion pressure.

METHODS

Nine pigs in ventricular fibrillation (VF) for 6 min, were treated with an automated compression/decompression device with a compression rate of 100 min(-1), a depth of 25% of the anterior-posterior diameter, and a compression to ventilation ratio of 15:2 with 100% decompression (standard CPR) for 3 min. Compression was then reduced to 75% of complete decompression for 1 min of CPR and then restored for another 1 min of CPR to 100% full decompression. Coronary perfusion pressure (CPP) was calculated as the diastolic (aortic (Ao)-right atrial (RA) pressure). Cerebral perfusion pressure (CerPP) was calculated multiple ways: (1) the positive area (in mmHg s) between aortic pressure and intracranial pressure (ICP) waveforms, (2) the coincident difference in systolic and diastolic aortic and intracranial pressures (mmHg), and (3) CerPP = MAP--ICP. ANOVA was used for statistical analysis and all values were expressed as mean +/- S.E.M. The power of the study for an alpha level of significance set at 0.05 was >0.90.

RESULTS

With CPR performed with 100%-75%-100% of complete chest wall recoil, respectively, the CPP was 23.3 +/- 1.9, 15.1 +/- 1.6, 16.6 +/- 1.9, p = 0.003; CerPP was: (1) area: 313.8 +/- 104, 89.2 +/- 39, 170.5 +/- 42.9, p = 0.03, (2) systolic aortic minus intracranial pressure difference: 22.8 +/- 3.6, 16.5 +/- 4, 23.7 +/- 4.5, p = n.s., and diastolic pressure difference: 5.7 +/- 3, -2.4 +/- 2.4, 3.2 +/- 2.5, p = 0.04 and (3) mean: 14.3 +/- 3, 7 +/- 2.9, 12.4 +/- 2.9, p = 0.03, diastolic aortic pressure was 28.1 +/- 2.5, 20.7 +/- 1.9, 20.9 +/- 2.1, p = 0.0125; ICP during decompression was 22.8 +/- 1.7, 23 +/- 1.5, 19.7 +/- 1.7, p = n.s. and mean ICP was 37.1 +/- 2.3, 35.5 +/- 2.2, 35.2 +/- 2.4, p = n.s.; RA diastolic pressure 4.8 +/- 1.3, 5.6 +/- 1.2, 4.3 +/- 1.2 p = 0.1; MAP was 52 +/- 2.9, 43.3 +/- 3, 48.3 +/- 2.9, p = 0.04; decompression endotracheal pressure, -0.7 +/- 0.1, -0.3 +/- 0.1, -0.75 +/- 0.1, p = 0.045.

CONCLUSIONS

Incomplete chest wall recoil during the decompression phase of CPR increases endotracheal pressure, impedes venous return and decreases mean arterial pressure, and coronary and cerebral perfusion pressures.