Perioperative Cerebral Ischaemia in Cardiac Surgery and BIS

A 46-year-old woman was monitored by bispectral index monitoring (BIS) during redo aortic and mitral valve replacement. On release of the aortic cross clamp there was a sudden, severe, unexplained, and sustained fall in the BIS value. Postoperatively, a CT scan was consistent with multiple ischaemic lesions. The lesions were presumed to be due to air embolism. This case suggests that a sudden unexplained and persistent fall in BIS may indicate cerebral ischaemia.

High concentrations of N-BNP are related to non-infectious severe SIRS associated with cardiovascular dysfunction occurring after off-pump coronary artery surgery †

BACKGROUND

Procalcitonin (PCT) blood concentrations are known to be an appropriate marker of severe systemic inflammatory response syndrome (SIRS) induced by coronary artery surgery with and without cardiopulmonary bypass. Pro-brain natriuretic peptide (N-BNP) is a newly described cardiac hormone considered to be an effective marker of severity and prognosis of acute coronary syndromes and congestive heart failure. We evaluated the perioperative time courses of PCT and N-BNP and investigated their role as early markers of severe SIRS (SIRS with cardiovascular dysfunction) induced by off-pump coronary artery bypass (OPCAB).

METHODS

Sixty-three patients were prospectively included. The American College of Chest Physicians Classification was used to diagnose SIRS and organ system failure to define severe SIRS. Serum concentrations of PCT and N-BNP were determined before, during and after surgery. Receiver operating characteristic curves and cut-off values were used to assess the ability of these markers to predict postoperative severe SIRS.

RESULTS

SIRS occurred in 25 (39%) patients. Nine of them (14%) showed severe SIRS. Significantly higher serum concentrations of N-BNP and PCT were found in patients with severe SIRS with peak concentrations respectively at 8887 pg ml(-1) (range 2940-29372 pg ml(-1)) for N-BNP and 9.50 ng ml(-1) (range 1-65 ng ml(-1)) for PCT. The area under the curve using N-BNP to detect postoperative severe SIRS was 0.799 before surgery (0.408 for PCT; P<0.01) and 0.824 at the end of surgery (0.762 for PCT; P<0.05).

CONCLUSIONS

N-BNP may be an appropriate marker indicating the early development of non-infectious postoperative severe SIRS after OPCAB.

Increased plasma levels of pro-brain natriuretic peptide in patients with cardiovascular complications following off-pump coronary artery surgery

OBJECTIVE

To compare N-terminal pro-brain natriuretic peptide (NT-pro-BNP), procalcitonin (PCT), and troponin I (Tn I) concentrations during and after coronary artery surgery in patients with or without cardiovascular complications.

DESIGN AND SETTING

Prospective, comparative study of 12 months in the cardiovascular intensive care unit in a university hospital.

PATIENTS

60 adult patients undergoing coronary artery bypass grafting with the off-pump technique.

MEASUREMENTS AND RESULTS

Plasma NT-pro-BNP, PCT, and Tn I levels were measured before and immediately after the end of operation and on PODs 1, and 2 and 3. We defined complicated postoperative course as myocardial infarction, cardiogenic shock, arrhythmias, congestive heart failure, and death occurring after the fourth postoperative hour. Receiver operating characteristic (ROC) curve cutoff values were used to assess the ability of the three markers to predict future cardiac events. The area under ROC curve (AUC) using NT-pro-BNP to detect a cardiovascular complicated course was 0.780 at the preoperative time and 0.850 at the end of surgery. A preoperative NT-pro-BNP value of 397 pg/ml had a sensitivity of 76%, specificity of 67%, and accuracy of 74% for predicting a subsequent cardiovascular complication. An immediate postoperative NT-pro-BNP value of 430 pg/ml had a sensitivity of 80%, specificity of 77%, and accuracy of 76%. Patients with preoperative NT-pro-BNP levels less than 275 pg/ml had an excellent postoperative prognosis. Other two markers were less appropriate.

CONCLUSIONS

NT-pro-BNP levels measured before and immediately after off-pump coronary artery bypass seem to be predictive of postoperative cardiac events.

[Perioperative management of ventricular assist devices]

OBJECTIVE

To review the perioperative anaesthetic management of ventricular assist devices.

DATA SOURCES

Extraction from Pubmed database of french and english articles on the perioperative anaesthetic management of ventricular assist devices for 15 years.

DATA SELECTION

The collected articles were reviewed and selected according to their quality and originality. The more recent data were selected.

DATA SYNTHESIS

Cardiac transplantation is an effective treatment for patients in end stage cardiac failure, but the average waiting time of 17 months, associated with the lack of organs (357 out of 832 candidates were transplanted in 1996) results in a high number of deaths in patients awaiting transplantation. The appearance in the 1980's, of the first ventricular assist device (VAD) provided a new possibility for the management of patients with end-stage cardiac failure awaiting transplantation ("bridge to transplant"). The perioperative anaesthetic management of these patients is complex. End stage cardiac failure, poorly responsive to pharmacological interventions, results rapidly in secondary organ dysfunctions. VADs produce a rapid improvement in haemodynamic, renal, hepatic and neuro-endocrine functions over a 2 months period, allowing transplantation to take place under optimal conditions. However VADs are not without complications (1 year mortality of 20%), of which the major are: infections (40%), perioperative haemorrhage (30%) and thrombo-embolic sequelae (30%). A best knowledge of pathophysiology of these complications is necessary to an optimal management of patients with ventricular assist devices.

The effect of hypertonic saline dextran solutions on hypoxic pulmonary vasoconstriction in anaesthetised piglets

Hypoxic pulmonary vasoconstriction (HPV) is a regulatory mechanism by which blood is diverted from poorly ventilated to better ventilated areas of the lung. The aim of the present study was to assess the extent to which hypertonic saline dextran and dextran solutions modify the magnitude of HPV during isovolumic haemodilution in intact acutely instrumented piglets. Eighteen large white piglets were anesthetised and assigned to two groups. Mean pulmonary arterial pressure (PAP) and cardiac output (Q), systemic arterial pressure and left arterial pressure (LAP) were measured. A decrease in Q was obtained by reducing venous return. This enabled measurement of transpulmonary pressures (mean PAP minus LAP) at four levels of Q in hyperoxia (inspiratory oxygen fraction (FiO2)=0.4) then in hypoxia (Fi,O2=0.1) in the two groups before blood soustraction (10 mL x kg(-1)) and after loading with sodium chloride (NaCl) 7.5% and dextran 6% or with dextran 6% alone. Dextran alone led to a decrease in mean PAP-LAP/Q values, and NaCl with dextran was associated with a significant shift of mean PAP-LAP/Q plots to higher pressures in hypoxia. Hypertonic saline dextran solution, as replacement fluid in isovolaemic haemodilution increased the magnitude of hypoxic pulmonary vasoconstriction, whereas dextran solution reduced it.

[Fusarium pleural effusion after a ventricular assist device]

We report the case of a 36-year-old man with a pleural effusion that complicates the postoperative period after the implantation of a ventricular assist device (VAD). The epidemiological, etiologic and therapeutic features of Fusarium infections were reviewed. Complete recovery of the infection was obtained after a treatment by liposomal amphotericine B (AmBisome) and 5 fluorocytosine.

Hyperprocalcitonemia is related to noninfectious postoperative severe systemic inflammatory response syndrome associated with cardiovascular dysfunction after coronary artery bypass graft surgery

OBJECTIVE

To investigate the role of 3 inflammatory parameters as early markers of severe systemic inflammatory response syndrome (SIRS) induced by coronary artery bypass graft surgery.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Patients (n = 63) undergoing elective coronary artery bypass graft surgery with cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

The American College of Chest Physicians/Society of Critical Care Medicine classification was used to diagnose SIRS. Organ system failures were used to define severe SIRS. Serum concentrations of the inflammatory parameters (procalcitonin [PCT], C-reactive protein, leukocyte count) were determined before, during, and after surgery. SIRS occurred in 30 (47%) patients after surgery. Seven patients (11%) showed SIRS with greater-than-or-equal1 organ dysfunction (severe SIRS), whereas patients without SIRS had no organ dysfunction. Significantly higher serum levels of PCT were found in patients with severe SIRS from the 6th postoperative hour until the 3rd postoperative day with a peak level of 10.7 plus minus 13.2 ng/mL. No significant difference was detected between serum PCT of patients with SIRS but without any organ dysfunction and patients without SIRS. PCT levels of these patients remained lower than 1.7 ng/mL. Compared with PCT, plasma concentrations of C-reactive protein peaked later on the 2nd postoperative day and were not able to confirm the severity of SIRS. Leukocyte counts were not significantly modified.

CONCLUSIONS

PCT seems to be an appropriate marker to identify the early development of noninfectious postoperative severe SIRS after coronary artery bypass graft surgery with cardiopulmonary bypass.

Sub-MAC concentrations of desflurane do not inhibit hypoxic pulmonary vasoconstriction in anesthetized piglets

PURPOSE

In vitro, halogenated agents reduce the pulmonary vasoconstrictor response to alveolar hypoxia in isolated perfused lungs. However, studies in intact animals have been less convincing. The aim of the present study was to assess the effect of sub-MAC concentrations of desflurane on hypoxic pulmonary vasoconstriction (HPV) in anesthetized piglets using the pressure/cardiac output relationship (P/Q).

METHODS

Eleven large white piglets were anesthetized and ventilated mechanically, alternatively in hyperoxia (FIO2=0.4) and in hypoxia (FIO2=0.12). Multipoint plots of pulmonary arterial pressure (PAP), or differences between PAP and left atrial pressure (LAP) against Q were generated by gradual inflation of a balloon advanced into the inferior vena cava. P/Q relationships were established in hyperoxia and in hypoxia at baseline, and then with gradual concentrations of desflurane.

RESULTS

In hypoxia, pressure gradients (PAP-LAP) increased significantly at every level of Q, demonstrating active pulmonary vasoconstriction. Desflurane did not affect these P/Q relationships either in hyperoxia, or in hypoxia, when compared with baseline.

CONCLUSION

Desflurane at a clinically relevant dose has no significant effect on HPV in anesthetized piglets.

Effects of sevoflurane on hypoxic pulmonary vasoconstriction in anaesthetized piglets

In vitro, halogenated agents reduce the pulmonary vasoconstrictor response to alveolar hypoxia in isolated perfused lungs. However, studies in intact animals have been less convincing. The aim of the present study was to assess the effect of sevoflurane on hypoxic pulmonary vasoconstriction (HPV) in anaesthetized piglets using the pressure/cardiac index relationship (P/Q). Ten large white piglets were anaesthetized and mechanically ventilated, alternately in hyperoxia (FIO2 = 0.4) and hypoxia (FIO2 = 0.12). Multipoint plots of pulmonary arterial pressure (PAP) or differences between PAP and left atrial pressure (LAP) against Q were generated by gradual inflation of a balloon introduced into the inferior vena cava. P/Q relationships were established in hyperoxia and hypoxia at baseline, and then with sevoflurane. In hypoxia, pressure gradients (PAP-LAP) increased at every level of Q, thus demonstrating active pulmonary vasoconstriction. Sevoflurane at 1 MAC did not affect these P/Q relationships in hyperoxia or hypoxia as compared with baseline. Sevoflurane at a clinically relevant concentration (1 MAC) has no significant effect on HPV in anaesthetized piglets.

Papillary muscle rupture caused by bacterial endocarditis: role of transesophageal echocardiography

A 22-year-old man had severe pulmonary congestion and required mechanical ventilation. Endocarditis was suspected because a 2/6 systolic murmur was heard at the apex and because Osler nodes were present. Transthoracic and transesophageal echocardiography allowed correct diagnosis of papillary muscle rupture causing massive mitral regurgitation. To our knowledge, this is the first reported case of papillary muscle rupture caused by bacterial endocarditis diagnosed by transthoracic and transesophageal echocardiography.

[Dysautonomia at 2 times in Guillain-Barré syndrome]

Autonomic dysfunction is described in a 63 year old woman suffering from Guillain-Barré syndrome. Bradyarrhythmias occurred during the convalescent phase, whereas neurologic and respiratory symptoms were improving; they were not related to bronchial aspiration. Their severity and the inefficiency of medical treatment led to the insertion of a demand pace-maker. Cardiac monitoring by the Holter method in severe cases of Guillain-Barré syndrome may detect potentially lethal arrhythmias, that may then be avoided by a demand pace-maker.