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Richard A Jonas

Publications and source records attributed to Richard A Jonas.

At least 19 recordsLinked to original sources
PubMed2006

Neurologic complications of cardiovascular surgery.

With significant advances in surgical technology and methodology, mortality from congenital heart surgery has been significantly reduced in recent decades. Therefore, focus has naturally turned towards predicting, evaluating, and preventing the neurodevelopmental morbidity associated with congenital heart disease and its treatment. This paper reviews recent publications evaluating preoperative neurologic abnormalities and injuries, current neurodevelopmental outcomes of congenital heart repair, and various neuromonitoring modalities that can be used to monitor neurologic function/dysfunction perioperatively. The rapidly advancing field of clinical neuromonitoring holds the promise of providing modalities that can detect injurious processes acutely to allow for intervention.

Cardiac Surgical Procedures↗
PubMed2006

Cerebral endothelial nitric oxide synthase expression is reduced after very-low-flow bypass.

BACKGROUND: In previous studies we have shown that delayed capillary reperfusion after low flow bypass predicts neurologic injury. In this acute study, we hypothesized that low flow reduces endothelial nitric oxide synthase (eNOS) expression, which may lead to more profound inflammatory response and delayed capillary perfusion. METHODS: Twelve piglets (13.2 +/- 0.7 kg) had a cranial window placed over the parietal cerebral cortex for direct examination of the microcirculation using intravital fluorescence microscopy. Animals were cooled to 15 degrees C or 34 degrees C on cardiopulmonary bypass (pH stat, hematocrit 30%, pump flow 100 mL/kg/minute) followed by 2 hours of low flow (50 mL/kg/minute) or very low flow (10 mL/kg/minute). Rhodamine staining was used to observe adherent and rolling leukocytes in postcapillary venules. The eNOS protein expression was determined by Western immunoblotting. RESULTS: High temperature and low flow rate correlated with significantly reduced eNOS expression (p < 0.01). Univariate comparisons based on Student t tests indicated that eNOS protein levels were lower at 34 degrees C than at 15 degrees C (0.7 +/- 0.6 vs 1.7 +/- 0.5, p < 0.01) and at 10 mL/kg per minute compared with 50 mL/kg per minute (0.8 +/- 0.7 vs 1.6 +/- 0.5, p = 0.03). Moreover, two-way analysis of variance revealed that temperature (F = 21.6, p < 0.001) and flow rate (F = 13.8, p = 0.005) were independent multivariate predictors of eNOS expression. During low flow bypass, eNOS was inversely correlated with numbers of adherent (p = 0.002) and rolling (p = 0.006) leukocytes, following an exponential decay curve closely. CONCLUSIONS: eNOS expression is reduced after very low flow bypass, particularly at a higher bypass temperature. This is associated with delayed capillary reperfusion. Reduced eNOS is also associated with increased white cell activation which may lead to greater neurologic injury.

Animals↗
PubMed2006

Interrupted aortic arch and aortic atresia with circle of Willis-dependent coronary perfusion.

We present a case of type B interrupted aortic arch and aortic atresia. This combination is usually incompatible with life. However, the presence of an aberrant right subclavian artery and enough blood flow through the circle of Willis allowed perfusion of the coronary arteries through retrograde carotid and aortic blood flow. A two-ventricular repair was successfully undertaken.

Aorta, Thoracic↗
PubMed2006

Aprotinin improves cerebral protection: evidence from a survival porcine model.

OBJECTIVE: Aprotinin is a serine protease inhibitor used during cardiac surgery to reduce blood loss and preserve platelet function. It has also been shown to reduce leukocyte activation during and after cardiopulmonary bypass. The goal of the study was to test the hypothesis that aprotinin could reduce cerebral injury after low-flow cardiopulmonary bypass and deep hypothermic circulatory arrest. METHODS: Sixteen piglets (mean weight, 13.6 +/- 1.3 kg) were randomly assigned to receive aprotinin or placebo (8 animals per group) before a 120-minute period of deep hypothermic circulatory arrest (15 degrees C) or 25 mL x kg(-1) x min(-1) low-flow cardiopulmonary bypass (25 degrees C or 34 degrees C). Piglets had a cranial window placed over the parietal cerebral cortex for direct examination of the microcirculation by means of intravital microscopy. Rhodamine-stained leukocytes were observed in postcapillary venules, with analysis for adhesion and rolling. Plasma was labeled with fluorescein isothiocyanate-dextran for assessment of functional capillary density. Neurologic and histologic scores were used as the primary outcome measures. RESULTS: During rewarming, the mean number of both rolling and adherent leukocytes was significantly lower after aprotinin administration (P < .05). At 5 and 15 minutes of rewarming, functional capillary density recovered faster with aprotinin treatment (P < .05). Functional outcome (neurologic deficit score) on postoperative day 1 was significantly improved in aprotinin-treated piglets (P < .05). CONCLUSIONS: Aprotinin reduces inflammation and improves neurologic outcome after a prolonged period of deep hypothermic circulatory arrest or low-flow cardiopulmonary bypass.

Animals↗
PubMed2005

Matching procedure to morphology improves outcomes in neonates with tricuspid atresia.

OBJECTIVE: This study was undertaken to characterize morphologic substrate of tricuspid atresia with ventriculoarterial concordance and discriminate management strategies that lead to successful definitive repair. METHODS: From 1999 to 2004, a total of 150 babies with type I tricuspid atresia were enrolled from first diagnosis at 26 institutions. Antegrade pulmonary blood flow was absent in 19%, restricted in 54%, and unrestricted in 28%. Competing-risk methodology determined the time-related prevalence and risk factors for death versus cavopulmonary anastomosis and subsequent death versus Fontan completion. RESULTS: Overall 5-year survival was 86%. Initial palliation included systemic-pulmonary arterial shunt in 64%, pulmonary artery banding in 11%, and cavopulmonary anastomosis in 24%. Median age at cavopulmonary anastomosis was 6 months, with 83% undergoing bidirectional Glenn shunt and 17% undergoing hemi-Fontan procedure. By the age of 2 years, 89% had cavopulmonary anastomosis, 6% were dead, and 4% remained alive without cavopulmonary anastomosis. Risk factors for death without cavopulmonary anastomosis included presence of mitral regurgitation (P = .03) and palliation with systemic-pulmonary arterial shunts not originating from the innominate artery (P = .04). Factors associated with decreased transition rate to cavopulmonary connection included patient variables (younger admission age to a participating institution, noncardiac anomalies) and procedural variables (larger systemic-pulmonary arterial shunt diameter, previous palliation). Of patients undergoing cavopulmonary anastomosis, 75% had undergone a Fontan operation within 3 years. CONCLUSION: Smaller shunt size and decreased pulmonary blood flow decrease mortality after initial palliation and increase the rate of successful transition to cavopulmonary anastomosis. Outcomes can be improved by placing smaller shunts from the innominate artery, especially in patients with any mitral regurgitation.

Cardiac Surgical Procedures↗
PubMed2005

Hypoxic-ischemic brain injury in infants with congenital heart disease dying after cardiac surgery.

Cardiac surgery for congenital heart disease is performed increasingly earlier in infancy, including in the neonatal period. With increased survival of infants, there is growing concern about the long-term neurological sequelae of hypoxic-ischemic injury due to congenital heart disease itself prior to surgery, corrective surgery with the use of low-flow cardiopulmonary bypass (CPB) and/or deep hypothermic circulatory arrest (DHCA), and/or unstable hemodynamic factors postoperatively. In analyzing the neuropathology of 38 infants dying after cardiac surgery, we tested a set of questions related to the severity and patterns of brain injury, CPB, DHCA, and age of the infants at the time of surgery. In all infants dying after cardiac surgery, irrespective of the modality, cerebral white matter damage [periventricular leukomalacia (PVL) or diffuse white matter gliosis] was the most significant lesion in terms of severity and incidence, followed by a spectrum of gray matter lesions. There was no significant association between the duration of deep hypothermic circulatory arrest and the degree of severity of overall brain injury, and the pattern of brain injury was similar irrespective of the modality of cardiac surgery. There was no significant association between the age at the time of surgery (neonatal versus postneonatal) and the severity of overall brain injury. The patterns of brain injury were not age-related in the limited time-frame analyzed, except that infants who developed acute PVL after both closed and DHCA/CPB surgery (14/38 infants, 34%) were significantly younger at death (median age 13.0 days) compared to unaffected infants (median age at death 42.5 days) (P=0.031). This observation suggests that neonatal (<30 postnatal days), but not postneonatal (>30 postnatal days), brains are at risk for acute PVL, and likely reflects the vulnerability of immature (pre-myelinating) white matter to hypoxia-ischemia.

Age Factors↗
PubMed2005

Improved outcome with composite graft versus homograft root replacement for children with aortic root aneurysms.

OBJECTIVE: Review of surgical repair of aortic root aneurysms using composite graft or homograft in children. METHODS: A consecutive series of 34 children (mean age 10.8+/-5.4 years) who underwent elective aortic root replacement using composite graft or homograft from 1987 to 2003 (mean follow-up 5.7+/-3.7 years). RESULTS: Preoperatively, the aortic annulus and aortic root average z-scores were 4.1+/-2.2 and 9.4+/-4.7, respectively. Composite graft root replacement was performed in 22 patients, and cryopreserved aortic homograft root replacement in 12 patients. There was one perioperative death in the homograft group due to sudden cardiovascular collapse. There was one late death in the composite graft group due to acute aortic dissection, and two late deaths in the homograft root replacement group, one at 7 months postoperatively due to coronary artery thrombosis and one due to severe chronic myocardial dysfunction 5 years postoperatively. One patient who initially had a homograft died due to mechanical valve thrombosis following reoperative composite graft replacement. Five patients had reoperations at a median of 7.1 years after initial surgery. One patient in the composite graft group underwent arch replacement. There were no graft related reoperations after composite graft root replacement, but 4 patients in the homograft group had reoperative composite graft replacement. Predictors of reoperation included age at surgery, lower weight, and longer ICU time (P<0.05). CONCLUSIONS: In children with aortic root aneurysms, reoperation is more common after homograft root replacement than composite graft replacement. Composite graft root replacement provides more stable repair of the aortic root.

Adolescent↗
PubMed2005

Total anomalous pulmonary venous connection: an analysis of current management strategies in a single institution.

BACKGROUND: Repair of total anomalous pulmonary venous connection (TAPVC) continues to be associated with significant mortality. We reviewed patients undergoing consecutive TAPVC repairs over a 10-year period at Children's Hospital Boston. The impact of current surgical and perioperative management strategies on short-term outcomes (postrepair pulmonary venous obstruction and mortality) is evaluated. METHODS: All patients with surgically corrected TAPVC from November 1989 to December 2000 were included. Charts were reviewed for patient demographics, operation variables, and postoperative course. RESULTS: There were 123 patients in the cohort, of which 72 (59%) were male. The median age and weight at operation were 10 days and 3.6 kg, respectively. Sixty-eight (55%) patients presented with pulmonary venous obstruction, and 65 (53%) underwent emergent TAPVC repair. Thirty-nine (32%) had single-ventricle anatomy, and 84 (68%) had two-ventricle anatomy. Thirty patients (24%) died. Kaplan-Meier survival at 1 month was 65% (95% confidence interval [CI], 55% to 75%) for single-ventricle patients versus 90% (95% CI, 90% to 100%) for two-ventricle patients; at 36 months it was 47% (95% CI, 35% to 59%) versus 87% (95% CI, 81% to 93%), respectively. By Cox multivariable regression analysis, a single ventricle (p < 0.001, hazard ratio, 4.8; 95% CI, 2.5 to 9.2) was an independent mortality risk factor. Prerepair pulmonary venous obstruction was a multivariate risk factor for death among single-ventricle patients. Postrepair pulmonary venous obstruction occurred in 11%. If year of operation is used as a predictor, two-ventricle patient survival has significantly improved (p < 0.05). CONCLUSIONS: Despite current interventions, single-ventricle patients continue to have a worse prognosis than two-ventricle patients.

Abnormalities, Multiple↗
PubMed2005

Neoaortic aneurysm after stage I Norwood reconstruction.

Treatment of hypoplastic left heart syndrome through staged repairs has resulted in patients surviving into adulthood. Use of either aortic or pulmonary homografts in performing the neoaortic reconstruction has become the standard of practice with relatively few problems. We report the case of an asymptomatic adolescent boy who had an enlarging neoaortic aneurysm and mild neoaortic regurgitation develop after undergoing a stage I Norwood procedure using a pulmonary homograft. Given the risk for rupture and a concern for further functional deterioration of the neoaortic valve, the patient underwent repair. Histologic examination showed a striking accumulation of myxoid material as well as abnormal vasculature in both the native and engrafted portions of the neoaorta.

Adolescent↗
PubMed2005

Specific bypass conditions determine safe minimum flow rate.

BACKGROUND: The purpose of this study is to define a safe minimum flow rate for specific bypass conditions using continuous monitoring with near-infrared spectroscopy and direct observation of the cerebral microcirculation. METHODS: Two series of experiments (n = 72 in each) were conducted in which piglets were cooled to a temperature of 15 degrees, 25 degrees, or 34 degrees C on cardiopulmonary bypass with hematocrit 20% or 30%, pH-stat management in all, followed by 1 or 2 hours of reduced flow (10, 25, or 50 mL.kg(-1).min(-1)). Animals in series one had a cranial window placed over the parietal cortex to evaluate the microcirculation with intravital microscopy. Plasma was labeled with fluorescein-isothiocyanate-dextran for assessment of functional capillary density (FCD) and microvascular diameter. In series two, near-infrared spectroscopy was utilized to detect tissue oxygenation index (TOI). Outcome measures included histologic and neurologic injury scores. RESULTS: The TOI during low flow and FCD during rewarming and after weaning from cardiopulmonary bypass were associated with neurologic injury. Failure of FCD to return to baseline during rewarming predicted worse functional and histologic outcome (p < 0.001). Regression analysis indicated that temperature and low-flow rate were multivariable predictors of TOI and FCD during rewarming (p < 0.001). CONCLUSIONS: Tissue oxygen index derived from near-infrared spectroscopy is a useful real-time monitor for detecting inadequate cerebral perfusion during cardiopulmonary bypass. Minimal safe pump flow rate varies according to the conditions of bypass: using pH stat management and with an hematocrit of either 20% or 30%, a flow rate as low as 10 mL.kg(-1).min(-1) is safe for as long as 2 hours at a temperature of 15 degrees C. However, under the same conditions at 34 degrees C, a flow rate of 10 mL.kg(-1).min(-1) is very likely to be associated with neurologic injury.

Animals↗
PubMed2005

Long-term outcome of surgically treated patients with corrected transposition of the great arteries.

OBJECTIVES: The purpose of the study was to examine long-term outcome after traditional surgical treatment of corrected transposition of the great arteries to provide a basis for comparison with new procedures, such as the double-switch or Senning-Rastelli procedures. METHODS: Patient- and procedure-related variables in 123 patients with corrected transposition and 2 functional ventricles operated on between 1963 and 1996 were analyzed. Patients with intracardiac procedures underwent either a traditional 2-ventricle repair or a Fontan procedure. RESULTS: The 1-, 5-, 10-, and 15-year survivals after the operation were 84%, 75%, 68%, and 61%, respectively. Patients requiring tricuspid valve replacement (27 patients) at any time during follow-up had a significantly worse outcome ( P < .001; hazard ratio, 4.4), whereas the best outcome was seen in patients undergoing the Fontan procedure (17 patients, 0 deaths). Right ventricular end-diastolic pressure of greater than 17 mm Hg before the operation ( P < .0001), complete heart block after the operation ( P = .001), subvalvular pulmonary stenosis ( P = .013), Ebstein malformation of the tricuspid valve ( P = .025), and preoperative systemic (right) ventricular dysfunction ( P = .041) were identified as risk factors for death at any time by means of univariate analysis. Ebstein malformation of the tricuspid valve ( P = .036; hazard ratio, 1.5) was identified as a risk factor for death by multivariate analysis. CONCLUSIONS: The long-term outcome of patients with corrected transposition after a classic surgical approach is unsatisfactory. The poorest outcome was seen in patients who required tricuspid valve replacement either at their initial operation or later during follow-up. Alternative surgical approaches, such as the double-switch, Senning-Rastelli, or Fontan procedures, are likely to have better long-term results, especially in the highest risk groups.

Analysis of Variance↗
PubMed2005

Tissue oxygenation index is a useful monitor of histologic and neurologic outcome after cardiopulmonary bypass in piglets.

OBJECTIVE: Tissue oxygenation index is a novel monitoring indicator derived by near-infrared spectroscopy. We hypothesized that tissue oxygenation index could predict a minimum safe flow rate for specific bypass conditions. METHODS: Thirty-six piglets (age, 43 +/- 5 days; weight, 9.0 +/- 1.1 kg) underwent cardiopulmonary bypass with cerebral near-infrared spectroscopy (NIRO-300; Hamamatsu Photonics K.K., Hamamatsu City, Japan). Animals were cooled for 40 minutes to 15 degrees C, 25 degrees C, or 34 degrees C (pH-stat, hematocrit value of 20% or 30%, and pump flow of 100 mL . kg -1 . min -1), followed by low-flow perfusion (10, 25, or 50 mL . kg -1 . min -1) for 2 hours. Neurologic and behavioral evaluations were determined for 4 days. The brain was then fixed for histologic assessment. Tissue oxygenation index was defined as the average signal during low-flow bypass. RESULTS: Animals with an average tissue oxygenation index of less than 55% showed cerebral injury, whereas animals with an index of greater than 55% showed minimal or no evidence of injury. Correlations were found between average tissue oxygenation index and histologic score (Spearman rho = -0.65, P < .001) and neurologic deficit score (Pearson r = -0.50, P = .002) on the first postoperative day. Temperature (P < .001), flow rate (P < .001), and hematocrit value (P = .002) were multivariable predictors of tissue oxygenation index, as determined by means of multivariable analysis of variance. CONCLUSION: Tissue oxygenation index is a useful monitor for defining the minimum safe flow rate during cardiopulmonary bypass. An index value of less than 55% is a strong predictor of neurologic injury.

Animals↗
PubMed2005

A randomized, double-blind, placebo-controlled pilot trial of triiodothyronine in neonatal heart surgery.

OBJECTIVE: This study was undertaken to evaluate the effect of triiodothyronine replacement on the early postoperative course of neonates undergoing aortic arch reconstruction. METHODS: We performed a randomized, double-blind, placebo-controlled trial of triiodothyronine supplementation in neonates undergoing either a Norwood procedure or two-ventricle repair of interrupted aortic arch and ventricular septal defect. Patients were assigned to receive a continuous infusion of triiodothyronine (0.05 micro/kg/h) or placebo for 72 hours after cardiopulmonary bypass. Primary end points were a composite clinical outcome score and cardiac index at 48 postoperative hours. RESULTS: We enrolled 42 patients (triiodothyronine n = 22, placebo n = 20). Baseline characteristics were similar in the treatment groups. Study drug was discontinued prematurely because of hypertension (n = 1) and ectopic atrial tachycardia (n = 1), both cases in the triiodothyronine group. Free and total triiodothyronine levels were higher in the triiodothyronine group than in the placebo group at 24, 48, and 72 postoperative hours (P < .001). The median clinical outcome scores were 2.0 (range 0-4) with triiodothyronine and 2.0 (range 0-7) with placebo (P = .046). Compared with those in the placebo group, neonates assigned to triiodothyronine had shorter median time to negative fluid balance (2.0 vs 2.5 days, P = .027). Cardiac index values were 2.11 +/- 0.64 L/min x m2 with triiodothyronine and 2.05 +/- 0.72 L/min x m2 with placebo (P = .81). Heart rate and diastolic blood pressure were not influenced by triiodothyronine supplementation, but systolic blood pressure was higher in the triiodothyronine group (P < .001). No serious adverse events were attributed to triiodothyronine administration. CONCLUSION: Triiodothyronine supplementation was safe and resulted in more rapid achievement of negative fluid balance after aortic arch reconstruction. Cardiac index at 48 hours was not significantly improved.

Aorta, Thoracic↗
PubMed2005

The Ross procedure is not the procedure of choice for the teenager requiring aortic valve replacement.

The Ross procedure was a remarkable technical achievement when it was introduced in 1967. Although the long-term results for the procedure when performed in adults using the technique of intra-aortic subcoronary freehand implantation have been satisfactory, the results for children using the technique of complete aortic root replacement have been less satisfactory. Not only have early outgrowth, calcification, and shrinkage of the pulmonary homograft used to reconstruct the right ventricular outflow tract been a problem but in addition some children have experienced excessive dilation of the neoaortic root as well as neoaortic valve regurgitation. In contrast to the Ross procedure, aortic valve repair and other forms of aortic valve replacement do not exclude the possibility of reoperation in the future using more advanced options such as tissue engineered leaflets or valves. Until more information is available regarding long-term performance of the pulmonary root when implanted as a neoaortic root, as well as improved results for reconstruction of the right ventricular outflow tract, the Ross procedure should be used rarely.

Adolescent↗
PubMed2005

The effect of extracorporeal life support on the brain: cardiopulmonary bypass.

This article reviews the mechanisms of brain injury associated with cardiopulmonary bypass. These include embolic injury of both a gaseous and particulate nature as well as global hypoxic ischemic injury. Ischemic injury can result from problems associated with venous drainage or with arterial inflow including a steal secondary to systemic to pulmonary collateral vessels. Modifications in the technique of cardiopulmonary bypass have reduced the risk of global hypoxic/ischemic injury. Laboratory and clinical studies have demonstrated that perfusion hematocrit should be maintained above 25% and preferably above 30%. Perfusion pH is also critically important, particularly when hypothermia is employed. An alkaline pH can limit cerebral oxygen delivery by inducing cerebral vasoconstriction as well as shifting oxyhemoglobin dissociation leftwards. If deep hypothermia is employed, it is critically important to add carbon dioxide using the so-called "pH stat" strategy. Oxygen management during cardiopulmonary bypass is also important. Although there is currently enthusiasm for using air rather than pure oxygen, ie, adding nitrogen, this does introduce a greater risk of gaseous nitrogen emboli since nitrogen is much less soluble than oxygen. The use of pure oxygen in conjunction with CO2 to apply the pH stat strategy is recommended. Many of the lessons learned from studies focusing on brain protection during cardiopulmonary bypass can be applied to the patient being supported with extracorporeal membrane oxygenation.

Brain↗
PubMed2005

An evaluation of bilateral monitoring of cerebral oxygen saturation during pediatric cardiac surgery.

Cerebral oximetry is a technique that enables monitoring of regional cerebral oxygenation during cardiac surgery. In this study, we evaluated differences in bi-hemispheric measurement of cerebral oxygen saturation using near-infrared spectroscopy in 62 infants undergoing biventricular repair without aortic arch reconstruction. Left and right regional cerebral oxygen saturation index (rSO2i) were recorded continuously after the induction of anesthesia, and data were analyzed at 12 time points. Baseline rSO2i measurements were left 65 +/- 13 and right 66 +/- 13 (P = 0.17). Mean left and right rSO2i measurements were similar (< or =2 percentage points/absolute scale units) before, during, and after cardiopulmonary bypass, irrespective of the use of deep hypothermic circulatory arrest. Further longitudinal neurological outcome studies are required to determine whether uni- or bi-hemispheric monitoring is required in this patient population.

Brain↗
PubMed2004

Identification of pressure passive cerebral perfusion and its mediators after infant cardiac surgery.

Cerebrovascular pressure autoregulation (CPA) regulates cerebral blood flow (CBF) in relation to changes in mean arterial blood pressure (MAP). Identification of a pressure-passive cerebral perfusion and the potentially modifiable physiologic factors underlying it has been difficult to achieve in sick infants. We previously validated the near-infrared spectroscopy-derived hemoglobin difference (HbD) signal (cerebral oxyhemoglobin - deoxyhemoglobin) as a reliable measure of changes in CBF in animal models. We now sought to determine whether continuous measurements of DeltaHbD would correlate to middle cerebral artery flow velocity (CBFV), allow identification and quantification of pressure-passive state, and help to delineate potentially modifiable factors. We enrolled 43 infants (2 d to 7 mo old) who were undergoing open cardiac surgery and cardiopulmonary bypass. At 6 and 20 h after surgery, we measured changes in HbD, CBFV (by transcranial Doppler), and MAP at different end-tidal CO(2) levels. We assigned a pressure-passive index (PPI) to each study on the basis of the relative duration of significant coherence between DeltaMAP and DeltaHbD. We found a significant relationship between DeltaHbD and DeltaCBFV at both time points. At 6 h after surgery, we showed high concordance (coherence > 0.5; PPI > or = 41%) between DeltaMAP and DeltaHbD, consistent with disturbed CPA in 13% of infants. End-tidal CO(2) values > or = 40 mm Hg and higher MAP variability both were associated with increased odds (p < 0.001) of autoregulatory failure. This approach provides a means to identify and quantify disturbances of CPA. High CO(2) levels and fluctuating MAP are two important preventable factors associated with disturbed CPA.

Blood Pressure↗