Determination of right ventricular volumes during aortic surgery

Anesthetic management of cesarean hysterectomy using intra-aortic balloon occlusion in a patient with Fontan circulation and placenta increta: a case report

BACKGROUND

In patients with Fontan circulation, hemorrhage can cause life-threatening circulatory collapse, since Fontan circulation strongly depends on the preload. Furthermore, parturients with placenta accreta spectrum are at a high risk of rapid and massive hemorrhage. Herein, we report the case of an intra-aortic balloon occlusion used for a Fontan-palliated parturient with placenta increta with successful anesthetic management.

CASE PRESENTATION

A 35-year-old-female with Fontan circulation diagnosed with placenta increta underwent a cesarean hysterectomy. The main goal during anesthetic management was to maintain sufficient preload. Infrarenal intra-aortic balloon occlusion was used to reduce intraoperative hemorrhage. The hemodynamic changes caused were well tolerated in this case.

CONCLUSIONS

Intra-aortic balloon occlusion was used in a Fontan-palliated parturient with placenta increta with successful anesthetic management.

Predicting fluid responsiveness during infrarenal aortic cross-clamping in pigs

OBJECTIVE

Infrarenal aortic cross-clamping (ACC) induces hemodynamic disturbances that may affect respiratory-induced variations in stroke volume and, therefore, affect the ability of dynamic parameters such as pulse-pressure variation (PPV) to predict fluid responsiveness. Since this issue has not been investigated yet to authors' knowledge, the hypothesis was tested that ACC may change PPV and impair its ability to predict fluid responsiveness.

DESIGN

Prospective laboratory experiment.

SETTING

A university research laboratory.

PARTICIPANTS

Nineteen anesthetized and mechanically ventilated pigs.

INTERVENTIONS

Two courses of volume expansion were performed using 500 mL of saline before and during ACC. Animals were monitored using a systemic arterial catheter, and a pulmonary arterial catheter (stroke volume, central venous pressure, pulmonary arterial occlusion pressure). Animals were defined as responders to volume expansion if stroke volume increased ≥ 15%.

RESULTS

Before ACC, 13 animals were responders. Fluid responsiveness was predicted by a PPV ≥ 14% with a sensitivity of 77% (95% CI = 46%-95%) and a specificity of 83% (95% CI = 36%-97%). The area under the receiver operating characteristic curve was 0.90(95% CI = 0.67-0.99) and was higher than those generated for central venous pressure and pulmonary arterial occlusion pressure. ACC induced an increase in PPV (p<0.0005). During ACC, 8 animals were responders. An 18% PPV threshold discriminated between responders and non-responders to volume expansion, with a sensitivity of 87% (95% CI = 47%-98%) and a specificity of 54% (95% CI = 23%-83%). The area under the receiver operating characteristic curve was 0.72 (95% CI = 0.47-0.90) and was not different from those generated for central venous pressure and pulmonary arterial occlusion pressure.

CONCLUSIONS

ACC induced a significant increase in PPV and reduced its ability to predict fluid responsiveness.

Pulmonary arterial and right ventricular responses to prophylactic albumin administration before aortic unclamping during abdominal aortic aneurysmectomy

During abdominal aortic aneurysmectomy (AAAectomy) and before aortic unclamping (XU), we studied the effects of albumin administration on pulmonary arterial and right ventricular responses in 39 anesthetized patients using a modified thermodilution technique. Group 1 patients (n = 18) were given no extra IV fluids. Group 2 patients (n = 21) were given additional albumin administration (5% albumin at 10 mL/kg) before XU. After XU, mean arterial blood pressure (MAP) decreased significantly in each group, and MAP and stroke volume index (SVI) were not significantly higher in Group 2 than in Group 1. At 5 min after XU, the patients in Group 2 had a higher mean pulmonary arterial pressure and pulmonary vascular resistance index and a lower right ventricular ejection fraction than those in Group 1 (P < 0.05), but their SVIs were well maintained. These results indicate that albumin administration before XU may not always prevent post-XU hypotension. It caused a significant increase in right ventricular afterload and a significant dilation of the right ventricular cavity; however, right ventricular function was almost equally maintained in both groups. However, because SVI did not increase in some patients (Group 2) with the increase in right ventricular end-diastolic volume index after XU, albumin administration should be performed carefully before XU during AAAectomy.

IMPLICATIONS

We studied the effects of albumin administration before aortic unclamping on pulmonary arterial and right ventricular responses during abdominal aortic aneurysmectomy using a modified thermodilution technique. Albumin administration before aortic unclamping may not always prevent hypotension, and it may cause a higher pulmonary arterial pressure than in patients without albumin administration.

Cardiovascular effects of moderate normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia in man

The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction of anaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group (H) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/05. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 +/- 7.9 to 39.3 +/- 7.1 ml.M-2 and from 73.8 +/- 20.3 to 94.9 +/- 18.5 ml.M-2 respectively (mean +/- s.d., both P < 0.05). However, heart rate decreased so that cardiac index did not change. O2 delivery decreased significantly (from 389 +/- 70 to 311 +/- 63 ml.min-1.m-2; P < 0.05), but was not different to the control group. O2 consumption was maintained by an increase in O2 extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that O2 delivery was similar in the two groups. O2 consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

Effect of controlled mechanical ventilation without positive end-expiratory pressure on right ventricular function after coronary artery bypass graft surgery

To evaluate the changes in right ventricular function during controlled mechanical ventilation (CMV) without positive end-expiratory pressure (PEEP) and during spontaneous breathing, we compared right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVEDVI) using a thermodilution technique after coronary artery bypass graft surgery. Patients were divided into two groups on the basis of changes in RVEDVI from CMV to spontaneous breathing: group U (n = 6) consisted of patients whose RVEDVI increased during spontaneous breathing compared with mechanical ventilation, group D (n = 3) consisted of patients whose RVEDVI decreased during spontaneous breathing compared with mechanical ventilation. PVRI values during CMV in group D were significantly larger than those in group U. Patients in group U showed no increase in RVEDVI, or decrease in RVEF during CMV without PEEP. However, the remaining 3 patients in group D showed an increase in RVEDVI and a decrease in RVEF during CMV. Mean PAP, RAP, RV systolic pressure, RV end-diastolic pressure, PWP, HR, and mean arterial pressure in both groups were comparable, and showed no significant difference at each of the measured points by 24 hrs postoperatively. Then, RVEF, RVEDVI and RVESVI measured by thermodilution technique is useful in evaluating ventricular function at bedside in ICU.