Goal-directed fluid therapy for microvascular free flap reconstruction following mastectomy: A pilot study

BACKGROUND:

Fluid management of the surgical patient has undergone a paradigm shift over the past decade. A change from ‘wet’ to ‘dry’ to a ‘goal-directed’ approach has been witnessed. The fluid management of patients undergoing free flap reconstruction is particularly challenging. This is typically a long operation with minimal surgical stimulation, and hypotension often ensues. The use of vasopressors in these cases is contraindicated to maintain adequate flow to the flap. Hypotension is often treated with intravenous fluid boluses. However, aggressive fluid administration to maintain adequate blood pressure can result in flap edema, venous engorgement and, ultimately, flap loss.

OBJECTIVE:

The primary objective of the present study was to determine whether goal-directed fluid therapy, titrated to maintain stroke volume variation ≤13%, with the use of an arterial pulse contour device results in improved postoperative cardiac index (CI) and stroke volume index (SVI) with reduced amounts of intravenous fluid. The primary end points studied were CI, SVI and cumulative crystalloid/colloid administration.

METHODS:

Twenty female patients undergoing simultaneous microvascular free flap reconstruction immediately following mastectomy were studied. Preoperative and intraoperative care were standardized. Each patient received intra-arterial blood pressure monitoring. In all patients, cardiac output measurement occurred throughout the intraoperative period using the arterial pulse contour device. Control patients had their fluid administered at the discretion of the anesthesiologist (blinded to results from the cardiac output device). Patients in the intervention group had a baseline crystalloid infusion of 5 mL/kg/h, with intravenous colloid boluses to maintain a stroke volume variation ≤13%.

RESULTS:

There was no difference in heart rate or mean arterial pressure between groups at the end of the operation. However, at the end of the operation, the intervention group had significantly higher mean (± SD) CI (3.8±0.8 L/min/m² versus 3.0±0.5 L/min/m²; P=0.02) and SVI (51.4±2.4 mL/m² versus 43.3±2.3 mL/m²; P=0.03). This improved CI and SVI was achieved with similar amounts of administered intraoperative fluid (5.8±0.5 mL/kg/h versus 5.0±0.7 mL/kg/h, control versus intervention). The intervention group required less postoperative fluid resuscitation during the early postoperative period (total fluid administered from end of operation to midnight of the operative day, 6.4±1.9 mL/kg/h versus 10.2±3.3 mL/kg/h, intervention versus control, respectively, P<0.01).

DISCUSSION:

Goal-directed fluid therapy using minimally invasive cardiac output monitoring resulted in improved end-operative hemodynamics, with less ‘rescue’ fluid administration during the perioperative period.     

Brainstem activation specific to migraine headache

Findings from functional imaging studies have shown activation of the brainstem during migraine without aura (MWOA) and activation of the hypothalamus during cluster headache. We assessed a patient with cluster headache and migraine by positron emission tomography during an active cluster headache after he had taken 1.2 glyceryl trinitate. The patient developed a typical MWOA, during which we saw activation in the dorsal rostral brainstem. There was no activation in the region of the hypothalamus. Our findings provide evidence that migraine involves the brainstem, and show several areas involved in cluster headaches. Our data show the potential for objective distinction between primary headache syndromes with functional imaging, in disorders hitherto distinguished on clinical grounds.     

Improvement of autoimmune hepatitis during pregnancy followed by flare-up after delivery

OBJECTIVES: Pregnancy in autoimmune hepatitis has been a rare event, but it has become more frequent with improved therapy. The present study aimed to analyze the consequences for mother and child in patients with autoimmune hepatitis. METHODS: Fourteen pregnancies have been followed in five patients with autoimmune chronic hepatitis (AIH) and in one with autoimmune sclerosing cholangitis (overlap AIH-PSC). RESULTS: Features of AIH improved markedly from the second trimester of pregnancy onward, allowing a decrease in immunosuppressive therapy. After delivery (or stillbirth in one patient), the activity of the autoimmune disease flared up rapidly in 12 of 14 events. CONCLUSIONS: Pregnancy induces a state of immune tolerance with improvement of the liver tests in AIH. This could result from a transition of TH1 to TH2 predominance during pregnancy. A flare-up often occurs after delivery. Preemptive increase of the immunosuppressive therapy is therefore advocated consecutive to delivery. Azathioprine use seems to be safe during pregnancy.     

The cephalic and external jugular veins: important alternative recipient vessels in left-sided microvascular breast reconstruction

BACKGROUND: The internal mammary and thoracodorsal vessels are the standard recipient sites in microsurgical breast reconstruction. We review our series of venous outflow alternatives when these vessels are inadequate or unusable. MATERIALS AND METHODS: A retrospective review of all free breast reconstructions was performed from July 2003 through December 2005. Outcomes were measured with regard to re-exploration, flap failure, and fat necrosis, with attention to the timing and side of reconstruction, as well as the presence or absence of radiation therapy. RESULTS: A total of 141 free breast reconstructions were performed during the study period. In seven cases (5%), alternative venous outflow vessels were selected (cephalic or external jugular vein). Nine anastamotic complications occurred, all of which involved the left internal mammary group (statistically significant for venous thrombosis, P = 0.0063) and three flaps failed. All cephalic and external jugular veins remained patent with no flap failures or fat necrosis within this group. CONCLUSION: The cephalic vein and external jugular vein are excellent alternatives for venous outflow in free breast reconstruction if neither the internal mammary nor thoracodorsal veins are sufficient, especially in left-sided reconstruction.     

Rotated alphanumeric characters do not automatically activate frontoparietal areas subserving mental rotation

Functional neuroimaging studies have identified a set of areas in the intraparietal sulcus and dorsal precentral cortex which show a linear increase in activity with the angle of rotation across a variety of mental rotation tasks. This linear increase in activity with angular disparity suggests that these frontoparietal regions compute rotational transformations. An open question is whether rotated target stimuli automatically activate these frontoparietal regions, even if the task does not require rotational transformations. To address this question, we performed functional MRI while healthy male volunteers made two-choice reaction-time judgements on canonical or mirror images of two-dimensional alphanumeric characters presented at various angles of rotation. Participants had either to decide whether characters were normal or mirror-reversed (i.e., mental rotation) or judge whether the stimulus was a letter or a number (i.e., stimulus categorization). Reaction times and error rates linearly increased with the angle of rotation for mirror-reversed judgements but not for number-letter judgements, showing that only the mental rotation task required rotational transformations of the characters. The mental rotation task was associated with a linear increase in neuronal activity with angular disparity in a bilateral set of frontoparietal areas, comprising the rostral dorsal premotor cortex, frontal eye field, ventral and medial intraparietal sulcus. Neuronal activity in these regions was neither increased nor modulated by angular disparity during the stimulus categorization task. These results suggest that at least for alphanumerical characters, areas implicated in mental rotation will only be called into action if the task requires a rotational transformation.