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PubMed2004

Increased myocardial matrix metalloproteinases in hypoxic newborn pigs during resuscitation: effects of oxygen and carbon dioxide.

BACKGROUND: Perinatal asphyxia is associated with cardiac dysfunction, and it is important to prevent further tissue injury during resuscitation. There is increasing evidence that myocardial matrix metalloproteinases (MMPs) are involved in myocardial hypoxaemia-reoxygenation injury. OBJECTIVE: To assess MMPs and antioxidant capacity in newborn pigs after global ischaemia and subsequent resuscitation with ambient air or 100% O(2) at different PaCO(2)-levels. METHODS: Newborn pigs (12-36 h of age) were resuscitated for 30 min by ventilation with 21% or 100% O(2) at different PaCO(2) levels after a hypoxic insult, and thereafter observed for 150 min. In myocardial tissue extracts, MMPs were analyzed by gelatin zymography and broad matrix-degrading capacity (total MMP). Total endogenous antioxidant capacity in myocardial tissue extracts was measured by the oxygen radical absorbance capacity (ORAC) assay. RESULTS: Matrix metalloproteinase-2 more than doubled from baseline values (P < 0.001), and was higher in piglets resuscitated with 100% O(2) than with ambient air (P = 0.012). The ORAC value was considerably decreased (P < 0.001). In piglets with elevated PaCO(2), total MMP-activity in the right ventricle was more increased than in the left ventricle (P = 0.008). In the left ventricle, total MMPactivity was higher in the piglets with low PaCO(2) than in the piglets with elevated PaCO(2) (P = 0.013). CONCLUSION: In hypoxaemia-reoxygenation injury the MMP-2 level was highly increased and was most elevated in the piglets resuscitated with 100% O(2). Antioxidant capacity was considerably decreased. Assessed by total MMP-activity, elevated PaCO(2) during resuscitation might protect the left ventricle, and probably increase right ventricle injury of the myocardium.

Animals↗
PubMed1991

'Not for resuscitation': the student nurses' viewpoint.

A variable proportion of hospital in-patients were deemed 'not for resuscitation'. Using a qualitative methodology, this phenomenon was investigated, placing particular emphasis upon the effect on nursing care. A total of 71 student nurses from two district general hospitals were interviewed and from transcriptions of tape recordings of the interviews, utilizing a grounded theory approach, the following conceptual categories were identified: the patients; decision making; changes in nursing care? are patients and/or their relatives consulted? the unsuccessful resuscitation; the right to die; and dying and death. Up to 40% of patients on medial wards, and up to 100% of patients on geriatric and psychiatric wards, were deemed 'not for resuscitation'. The most junior members of the medical team had the power to make this decision without consultation with the nursing staff, patients or relatives. Nurses spent more time attending to patients 'not for resuscitation', but physiotherapists and medical staff withdrew. Informants felt that subjecting patients to cardiopulmonary resuscitation was incompatible with a dignified death. Senior members of the nursing staff were felt to be unfeeling in dealing with the distress of their juniors when laying out deceased patients. More discussion and joint decision making between health care professionals would alleviate some of the student nurses' distress concerning patients who are 'not for resuscitation'.

Adult↗
PubMed2004

Haemodynamic effects of volume resuscitation by hypertonic saline-dextran (HSD) in porcine acute cardiac tamponade.

BACKGROUND: Hypertonic saline-dextran (HSD) has been utilized for small-volume resuscitation in acute circulatory shock. However, HSD has also been reported to induce myocardial depression. The aim of this study was to examine the effects of HSD on cardiac performance and splanchnic perfusion in a low cardiac output model based on experimental cardiac tamponade. METHODS: Seven anaesthetized, mechanically ventilated pigs of both sexes (weight 24 +/- 2 kg, mean +/- SEM) completed a randomized, cross-over protocol. A low cardiac output state was established by intrapericardial infusion of dextran. Animals were resuscitated by bolus infusions (4 ml kg(-1) in 2 min) of either 7.5% hypertonic saline-dextran or Ringer's acetated solution (RAc) and then observed during tamponade (20 min) and following its release (40 min). Central haemodynamics, portal venous (QPV) and renal arterial (QRA) flows were measured together with gastric, jejunal, hepatic and renal laser-Doppler flowmetry. RESULTS: Resuscitation using HSD in a low cardiac output state completely restored QPV and improved gastric, jejunal, hepatic and renal microcirculation as assessed by laser-Doppler flowmetry while no significant effect was observed in QRA. No such beneficial effects could be observed when animals were resuscitated using RAc. The improved haemodynamic state by HSD was maintained following release of cardiac tamponade while perfusion in RAc resuscitated animals returned to baseline or even remained depressed (hepatic and renal microcirculation). No signs of cardiodepression by HSD were observed. CONCLUSION: Resuscitation using HSD in a low cardiac output state restored splanchnic perfusion and microcirculation without any signs of cardiodepression.

Anesthesia↗
PubMed2004

Fluid resuscitation from severe hemorrhagic shock using diaspirin cross-linked hemoglobin fails to improve pancreatic and renal perfusion.

BACKGROUND: Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas. METHODS: In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation. RESULTS: All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group. CONCLUSION: DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas.

Algorithms↗
PubMed2004

Neonatal resuscitation: review of ventilation equipment and survey of practice in Australia and New Zealand.

OBJECTIVE: The equipment used to provide positive pressure ventilation at neonatal resuscitation varies between institutions. Available devices were reviewed and their use surveyed in a geographically defined region. The aim of this study was to establish which resuscitation equipment is used at neonatal intensive care units in Australia and New Zealand. METHODS: A questionnaire was sent to a neonatologist at each of the 29 neonatal intensive care units in Australia and New Zealand, asking which resuscitation equipment they used. If it was not returned, follow up was by email and telephone. RESULTS: Data was obtained from all units. Round face masks are used at all centres. Anatomically shaped masks are infrequently used at two of the three centres (10%) that have them. Straight endotracheal tubes are used exclusively at 23 (79%) centres. Shouldered tubes are used infrequently at three of the six centres that have them. The Laerdal Infant Resuscitator self-inflating bag is used at 22 (76%) centres. Flow-inflating bags are used at 12 (41%) centres. The Neopuff Infant Resuscitator is used at 14 (48%) centres. Varying oxygen concentrations are provided at delivery at 6/25 (24%) centres. CONCLUSIONS: There is a paucity of evidence for the efficacy of the equipment used currently to resuscitate newborn infants. This complete survey of the tertiary centres in a geographical region shows considerable variation in practice, reflecting this lack of evidence and consequent uncertainty among clinicians. Further research is necessary to determine which devices are preferable for this most important and common intervention.

Australia↗
PubMed2004

Paediatric resuscitation by phone: the call back.

OBJECTIVE: To assess whether the nationwide introduction of standardized paediatric resuscitation training has resulted in an increase in resuscitation knowledge from 1995 and whether this increase in knowledge is greater in those who have attended a resuscitation training course within the last year. METHODS: National telephone survey of paediatric residents. RESULTS: A total of 128 out of a possible 140 residents responded. The mean score in 2002 was significantly higher than in 1995. Those 2002 respondents who had attended a course scored significantly higher than both 1995 respondents, and those 2002 respondents who had not attended a course. There was no significant difference between those 2002 respondents who had not attended a course and the 1995 respondents. CONCLUSION: There has been a significant increase in resuscitation knowledge from 1995 to 2002. This improvement has occurred over a period coinciding with the nationwide introduction of standardized resuscitation training. The authors suggest that this improvement is, in part, due to the introduction of standardized paediatric resuscitation training.

Adult↗
PubMed2005

Knowledge gained by pediatric residents after neonatal resuscitation program courses.

BACKGROUND: The efficacy of the Neonatal Resuscitation Program (NRP) courses was previously evaluated, demonstrating good retention of knowledge in the participants. However, there is a lack of information regarding the participants' performance in relation to the different steps of neonatal resuscitation. We aimed to assess the knowledge gained and retained by pediatric residents who participated in a NRP course in relation to the different steps. METHODS: An 80-item questionnaire derived from the standard test contained in the American Heart Association and American Academy of Pediatrics Neonatal Resuscitation Manual was given to 25 pediatric residents before, immediately after and 6 months after the course. RESULTS: The percentages of correct answers significantly improved from before (37.6 +/- 3.1%) to immediately after the course (94.1 +/- 0.9%) (P < 0.001). The percentages at the 6 months follow-up test (62.7 +/- 2.2%) significantly decreased from posttest (P < 0.001), but remained significantly higher with respect to pretest performance (P < 0.001). The percentages of correct answers were different among the four neonatal resuscitation steps during the entire study (pretest, posttest and follow-up test). CONCLUSIONS: The knowledge gained by pediatric residents participating in the NRP course was very high, but was only partially retained over time. In particular, it was different among the four steps of neonatal resuscitation suggesting further studies on teaching resuscitation.

Child↗
PubMed2001

Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes?

OBJECTIVE: To measure the ability of cardiac sonography and capnography to predict survival of cardiac arrest patients in the emergency department (ED). METHODS: Nonconsecutive cardiac arrest patients prospectively underwent either cardiac ultrasonography alone or in conjunction with capnography during cardiopulmonary resuscitation at two community hospital EDs with emergency medicine residency programs. Cardiac ultrasonography was carried out using the subxiphoid view during pauses for central pulse evaluation and end-tidal carbon dioxide (ETCO(2)) levels were monitored by a mainstream capnograph. A post-resuscitation data collection form was completed by each of the participating clinicians in order to assess their impressions of the facility of performance and benefit of cardiac sonography during nontraumatic cardiac resuscitation. RESULTS: One hundred two patients were enrolled over a 12-month period. All patients underwent cardiac sonographic evaluation, ranging from one to five scans, during the cardiac resuscitation. Fifty-three patients also had capnography measurements recorded. The presence of sonographically identified cardiac activity at any point during the resuscitation was associated with survival to hospital admission, 11/41 or 27%, in contrast to those without cardiac activity, 2/61 or 3% (p < 0.001). Higher median ETCO(2) levels, 35 torr, were associated with improved chances of survival than the median ETCO(2) levels for nonsurvivors, 13.7 torr (p < 0.01). The multivariate logistic regression model, which evaluated the combination of cardiac ultrasonography and capnography, was able to correctly classify 92.4% of the subjects; however, of the two diagnostic tests, only capnography was a significant predictor of survival. The stepwise logistic regression model, summarized by the area under the receiver operator curve of 0.9, furthermore demonstrated that capnography is an outstanding predictor of survival. CONCLUSIONS: Both the sonographic detection of cardiac activity and ETCO(2) levels higher than 16 torr were significantly associated with survival from ED resuscitation; however, logistic regression analysis demonstrated that prediction of survival using capnography was not enhanced by the addition of cardiac sonography.

Capnography↗
PubMed2005

Neonatal resuscitation 1: a model to measure inspired and expired tidal volumes and assess leakage at the face mask.

BACKGROUND: Neonatal resuscitation is a common and important intervention, and adequate ventilation is the key to success. In the delivery room, positive pressure ventilation is given with manual ventilation devices using face masks. Mannequins are widely used to teach and practise this technique. During both simulated and real neonatal resuscitation, chest excursion is used to assess tidal volume delivery, and leakage from the mask is not measured. OBJECTIVE: To describe a system that allows measurement of mask leakage and estimation of tidal volume delivery. METHODS: Respiratory function monitors, a modified resuscitation mannequin, and a computer were used to measure leakage from the mask and to assess tidal volume delivery in a model of neonatal resuscitation. RESULTS: The volume of gas passing through a flow sensor was measured at the face mask. This was a good estimate of the tidal volume entering and leaving the lung in this model. Gas leakage between the mask and mannequin was also measured. This occurred principally during inflation, although gas leakage during deflation was seen when the total leakage was large. A volume of gas that distended the mask but did not enter the lung was also measured. CONCLUSION: This system can be used to assess the effectiveness of positive pressure ventilation given using a face mask during simulated neonatal resuscitation. It could be useful for teaching neonatal resuscitation and assessing ventilation through a face mask.

Education, Medical, Graduate↗
PubMed1996

Effectiveness of the BBC's 999 training roadshows on cardiopulmonary resuscitation: video performance of cohort of unforewarned participants at home six months afterwards.

OBJECTIVE: To examine the competence of a cohort trained in cardiopulmonary resuscitation by the BBC's 999 training roadshows. DESIGN: Descriptive cohort study applying an innovative testing procedure to a nationwide systematic sample. The test sample received an unsolicited home visit and without warning were required to perform cardiopulmonary resuscitation on a manikin while being videoed. The videos were then analysed for effectiveness and safety using the new test. SETTING: Nine cities and surrounding areas in the United Kingdom. SUBJECTS: 280 people aged between 11 and 72. RESULTS: Thirty three (12%) trainees were able to perform effective cardiopulmonary resuscitation, but of these 14 (5%) performed one or more elements in a way that was deemed to be potentially injurious. Thus only 19 (7%) trainees were able at six months to provide safe cardiopulmonary resuscitation. In addition, large numbers of subjects failed to shout for help, effectively assess the status of the patient, or alert an ambulance. Significantly better performances were recorded by those under 45 years old (31 (14%) v 2 (4%) gave effective performances respectively, P < 0.05), those who had attended a subsequent cardiopulmonary resuscitation course (8 (40%) v 25 (10%) gave effective performances respectively, P < 0.0001), and those confident in their initial ability (26 (20%) v 7 (6%) gave effective performances respectively, P < 0.005). Females were significantly less likely than males to perform procedures in a harmful way (117 (62%) v 10 (12%) performed safely respectively, P < 0.005). CONCLUSION: Television is an effective means of generating large training cohorts. Volunteers will cooperate with unsolicited testing in their home, such testing being a realistic simulation of the stress and lack of forewarning that would surround a real event. Under such conditions the performance of cardiopulmonary resuscitation was disappointing. However, retraining greatly improves performance.

Adolescent↗
PubMed2002

Recognition of death and termination of cardiac resuscitation attempts by UK ambulance personnel.

OBJECTIVES: To identify whether the practice of the UK ambulance trusts comply with national recommendations with respect to when ambulance personnel are allowed to recognise death and/or terminate resuscitation attempts in the adult, normothermic, non-traumatic cardiac arrest. METHODS: Questionnaire study of 39 ambulance trusts. RESULTS: At the time of the study (summer 2000), 23 trusts operated separate policies for recognition of death and termination of resuscitation, two had policies for recognition of death alone, two had policies for termination of resuscitation alone, five operated a policy purely for termination of resuscitation attempts after a limited period of CPR, and seven had no protocols other than "the presence of rigor mortis, postmortem staining or injuries incompatible with life". Only eight trusts conformed to the protocols for both recognition of death and termination of resuscitation attempts recommended by the Joint Royal Colleges Ambulance Liaison Committee (JRCALC). CONCLUSION: The JRCALC has proposed guidelines for recognition of death and terminating resuscitation attempts in the adult normothermic non-traumatic cardiac arrest. Despite this, there was still considerable variance in the practice of the UK ambulance trusts.

Cardiopulmonary Resuscitation↗
PubMed1985

Evaluation of lay skills in cardiopulmonary resuscitation.

The theoretical knowledge and practical performance of 166 lay people attending a short cardiopulmonary resuscitation course were evaluated according to the American Heart Association standards. Before tt course no participant was able to perform even a bad attempt at cardiopulmonary resuscitation. Theoretical knowledge was good at the end of the course and at the refresher course six months later. At the end of the initial course 65% (57/88) of the participants examined could adequately compress and ventilate the manikin. After six months 44% (30/68) could perform resuscitation adequately. Women were as proficient as men, and elderly people in general were as proficient as the younger ones. The skill of carotid artery palpation was surprisingly well retained after six months. Data on pulmonary ventilation and cardiac massage were recorded simultaneously on a recording resuscitation manikin. When these objective data were compared with the American Heart Association standards only a few participants were able to perform correct cardiopulmonary resuscitation. The number of compressions and ventilations per minute were often insufficient. A large discrepancy between self, subjective, and objective assessment of cardiopulmonary resuscitation knowledge and performance was found. The importance of a rapid diagnosis, an immediate call for help, an adequate rate of cardiac massage, and a reduction in the time needed for ventilation should be emphasised at these courses. Refresher courses should be provided at least twice a year.

Adolescent↗
PubMed2001

Activation of poly(ADP-ribose) polymerase in severe hemorrhagic shock and resuscitation.

This study examines activation of poly(ADP-ribose) polymerase (PARP) in the ileum during hemorrhage and resuscitation and determines if inhibition of PARP reduces organ dysfunction and metabolic acidosis. Awake, nonheparinized rats were hemorrhaged (40 mmHg, 60 min). Resuscitation used Ringer's solution (2 1/3 x shed volume) and packed red blood cells (2/3 shed volume). Ileal PARP activity was elevated at the end of hemorrhage (3.6-fold) and 10 min of resuscitation (5-fold). The subsequent decline in PARP activity observed after 60 min of resuscitation was not due to cleavage by caspase-3. Ileum permeability increased 10-fold and circulating liver enzymes increased 4- to 6-fold following 60 min of resuscitation in animals pretreated with 3-aminobenzoic acid, a structural analog that does not inhibit PARP. Pretreatment with 3-aminobenzamide (3-AB), a PARP inhibitor, reduced these changes, whereas posttreatment with a bolus of 3-AB was ineffective. Metabolic acidosis, accumulation of lactate, and base deficit was reduced by pretreatment with 3-AB. PARP is activated in the ileum by hemorrhage and by resuscitation. Activation of PARP contributes to organ dysfunction in the ileum and liver and appears to be central to the development of metabolic acidosis.

Acidosis↗
PubMed1992

Diltiazem restores cardiac output and improves renal function after hemorrhagic shock and crystalloid resuscitation.

Although calcium antagonists produce salutary effects after shock and ischemia, it is unknown whether such agents restore the depressed cardiac output (CO) and renal function in a nonheparinized model of trauma-hemorrhage and resuscitation. To study this, rats underwent a midline laparotomy (i.e., trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of the maximum bleedout was returned in the form of Ringer lactate (RL). They were then resuscitated with four times the volume of shed blood with RL over 60 min. Diltiazem (400 micrograms/kg body wt) or an equal volume of saline was infused intravenously over 95 min. This infusion was started during the last 15 min of resuscitation. CO was determined by indocyanine green dilution. Glomerular filtration rate (GFR) was assessed with [3H]inulin clearance, and cortical microcirculation was examined by laser Doppler flowmetry. Results indicate that crystalloid resuscitation alone transiently restored but did not maintain CO after hemorrhage. Diltiazem infusion in conjunction with crystalloid resuscitation, however, restored and maintained CO and cortical microcirculation. Although GFR decreased in both groups, the values in diltiazem-treated animals were significantly higher than those in the sham-operated animals. Furthermore, diltiazem markedly decreased tissue water content. Thus diltiazem appears to be a promising adjunct in the treatment of hemorrhagic shock even in the absence of blood resuscitation.

Animals↗
PubMed1993

Endothelial cell dysfunction occurs very early following trauma-hemorrhage and persists despite fluid resuscitation.

Although hemorrhage produces alterations in hemodynamics and cellular functions, it remains unknown if endothelial cell function is depressed in a nonheparinized model of trauma-hemorrhage and resuscitation. To study this, rats underwent a 5-cm midline laparotomy (i.e., trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of maximal bleed-out volume was returned in the form of Ringer lactate (RL). They were then resuscitated with four times the volume of the shed blood with RL over 60 min. At the time of maximal bleed out (approximately 50 min from the onset of hemorrhage), 1.5, and 4 h after the completion of resuscitation, aortic rings (approximately 2.5 mm in length) were isolated and mounted in organ chambers. Dose responses for an endothelium-dependent vasodilator (acetylcholine) and endothelium-independent vasodilator (nitroglycerin) were determined. The results indicate that endothelium-dependent relaxation was depressed at the time of maximal bleed out and persisted even after resuscitation. However, there was no significant difference in nitroglycerin-induced relaxation at any point during the study period. In addition, hypoxia-induced contraction, a process mediated by endothelium-derived contracting factor, decreased significantly following hemorrhage and resuscitation. Thus endothelial cell dysfunction (i.e., reduced release of endothelium-derived relaxing and contracting factors) occurs very early after trauma-hemorrhage and persists despite fluid resuscitation.

Acetylcholine↗
PubMed2004

Resuscitation of depressed newborn infants with ambient air or pure oxygen: a meta-analysis.

BACKGROUND: It is discussed whether depressed newborn infants should be resuscitated with room air or 100% O2. OBJECTIVE: To perform a systematic review and meta-analysis including studies that report resuscitation of depressed newly born infants with 21 or 100% O2. METHODS: Inclusion criterion was randomized or pseudo-randomized, blinded or not, studies of depressed newborn infants resuscitated with either 21 or 100% O2. The literature was searched in Medline/Pubmed/EMBASE and The Cochrane library databases. All identified studies were included. RESULTS: Five studies fulfilled the inclusion criterion in which 881 infants were resuscitated with 21% O2 and 856 with 100% O2. Neonatal mortality was 8.0 vs. 13.0% in the 21 and 100% O2 groups respectively, OR 0.57, 95% CI 0.42-0.78. In term infants neonatal mortality was 5.9% in the 21% O2 group and 9.8% in the 100% O2 group, OR 0.59, 95% CI 0.40-0.87. The figures for the premature infants were very similar. In infants with 1-min Apgar score <4, OR for neonatal mortality was 0.81 (95% CI 0.54-1.21). Apgar score at 5 min and heart rate at 90 s were significantly higher, and time to first breath significantly earlier in infants given 21% O2 compared with 100% O2. CONCLUSIONS: A systematic review and meta-analysis demonstrated that neonatal mortality is significantly reduced when depressed newly born infants are resuscitated with ambient air instead of pure oxygen. For infants with low 1-min Apgar score (<4), no significant difference in neonatal mortality was found. Recovery was faster in infants resuscitated with 21% O2 than 100% O2.

Air↗
PubMed1988

Failure of epinephrine to improve the balance between myocardial oxygen supply and demand during closed-chest resuscitation in dogs.

Although large doses of epinephrine increase coronary perfusion pressure and flow during cardiopulmonary resuscitation, epinephrine also increases myocardial oxygen consumption during ventricular fibrillation. To test the hypothesis that epinephrine improves the balance between myocardial oxygen supply and demand during cardiopulmonary resuscitation, myocardial adenosine 5'-triphosphate (ATP) and lactate concentrations were measured before and immediately after 10 minutes of cardiopulmonary resuscitation in 10 control dogs and 10 dogs given intravenous epinephrine (1-mg bolus followed by 0.2 mg/min). Left ventricular myocardial blood flow during cardiopulmonary resuscitation was measured with radioactive microspheres and was significantly higher in the epinephrine group (48 +/- 11 vs. 21 +/- 4 ml/min/100 g, p less than 0.05). However, myocardial lactate concentration increased significantly (p less than 0.01) after cardiopulmonary resuscitation in both groups and tended to increase more in epinephrine-treated animals. Myocardial ATP concentration decreased significantly (p less than 0.05) and by comparable amounts in the two groups. These findings suggest that large doses of epinephrine may fail to improve the balance between myocardial oxygen supply and demand during cardiopulmonary resuscitation, even when they result in a substantial increase in coronary blood flow.

Adenosine Triphosphate↗
PubMed1985

Transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs.

Elevation of intrathoracic pressure during cardiopulmonary resuscitation generates carotid pressure and flow, but also increases intracranial pressure. This increase in intracranial pressure may limit cerebral blood flow. Therefore, we performed studies designed to quantify the extent of this transmission and to identify the mechanism of transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs. Intracranial pressure increased during the chest compression phase of all modes of cardiopulmonary resuscitation tested. During simultaneous compression-ventilation cardiopulmonary resuscitation, change in intracranial pressure (mm Hg) = 0.33 change in intrathoracic pressure (mm Hg) + 2.02 (r = 0.86) and was not significantly different from the relationship observed during conventional cardiopulmonary resuscitation. The magnitude of transmission of intrathoracic pressure to the intracranial space was increased by binding the abdomen and by raising the baseline intracranial pressure. No single route accounted for transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation. Intracranial pressure fluctuations were unrelated to either carotid arterial or jugular venous pressure, and were found instead to be the result of pressure transmission by blood in non-valved veins and by cerebrospinal fluid. This was determined by three maneuvers. First, obstruction of cerebrospinal fluid flow by ligation of the cervical spinal cord reduced intracranial pressure (P less than 0.001) and made the change in intracranial pressure equivalent to pressure changes at the confluence of the intracranial venous sinuses, without affecting pressure changes at the confluence of the intracranial venous sinuses. Second, ligation of the cervical spinal cord and one of the two longitudinal vertebral veins adjacent to the cervical cord reduced the pressure changes in the intracranial space and at the confluence of the intracranial venous sinuses to about 60% of the levels observed when the cervical cord alone was ligated. Thus, the non-valved longitudinal vertebral veins appear to be the vascular channels of critical importance to pressure transmission. Finally, pressure changes in the thoracic cerebrospinal fluid were increased (P less than 0.05) by cord ligation, even after exsanguination minimized pressure transmission via blood-filled channels, indicating direct transmission of intrathoracic pressure through intervertebral foramina to the cerebrospinal fluid.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗