Intraoperative fluids: how much is too much?

There is increasing evidence that intraoperative fluid therapy decisions may influence postoperative outcomes. In the past, patients undergoing major surgery were often administered large volumes of crystalloid, based on a presumption of preoperative dehydration and nebulous intraoperative 'third space' fluid loss. However, positive perioperative fluid balance, with postoperative fluid-based weight gain, is associated with increased major morbidity. The concept of 'third space' fluid loss has been emphatically refuted, and preoperative dehydration has been almost eliminated by reduced fasting times and use of oral fluids up to 2 h before operation. A 'restrictive' intraoperative fluid regimen, avoiding hypovolaemia but limiting infusion to the minimum necessary, initially reduced major complications after complex surgery, but inconsistencies in defining restrictive vs liberal fluid regimens, the type of fluid infused, and in definitions of adverse outcomes have produced conflicting results in clinical trials. The advent of individualized goal-directed fluid therapy, facilitated by minimally invasive, flow-based cardiovascular monitoring, for example, oesophageal Doppler monitoring, has improved outcomes in colorectal surgery in particular, and this monitor has been approved by clinical guidance authorities. In the contrasting clinical context of relatively low-risk patients undergoing ambulatory surgery, high-volume crystalloid infusion (20-30 ml kg(-1)) reduces postoperative nausea and vomiting, dizziness, and pain. This review revises relevant physiology of body water distribution and capillary-tissue flow dynamics, outlines the rationale behind the fluid regimens mentioned above, and summarizes the current clinical evidence base for them, particularly the increasing use of individualized goal-directed fluid therapy facilitated by oesophageal Doppler monitoring.     

Aprotinin dosing: how much is enough?

Coagulopathy and postoperative bleeding continue to be a major concern for patients undergoing cardiac surgery with cardiopulmonary bypass. Pharmacologic attenuation of this morbidity has been one area that clinicians have held in high interest. Aprotinin, a serine protease inhibitor, has been shown to be effective in reducing bleeding as well as the need for blood component transfusions. Although effective, aprotinin is an expensive drug and this, in conjunction with a cost-conscious community, has led clinicians to determine what is the lowest effective dose of aprotinin. From these studies, various aprotinin dosing regimens have been studied with differing results. The purpose of this work is to review the effectiveness of the various dosing strategies and to examine potential benefits of a dosing regimen based on a patient's weight, which may allow clinicians to achieve the maximal benefits from aprotinin without overdosing patients.     

How much liver resection is too much?

BACKGROUND: Hepatic failure occurring after liver resection carries a poor prognosis and is a complication dreaded by surgeons. Inadequate reserve in the remaining parenchyma leads to a steady decrease in liver function, inability to regenerate, and progression to liver failure. For this reason, many methods to quantify functional hepatic reserve have been developed. METHODS: This article reviews the main methods used in the assessment of hepatic reserve in patients undergoing hepatectomy and their use in operative decision making. RESULTS: A range of methods to categorically quantify the functional reserve of the liver have been developed, ranging from scoring systems (such as the Child-Pugh classification) to tests assessing complex hepatic metabolic pathways to radiological methods to assess functional reserve. However, no one method has or is ever likely to emerge as a single measure with which to dictate safe limits of resectability. CONCLUSIONS: In the future, the role of residual liver function assessment may be of most benefit in the routine stratification of risk, thus enabling both patient consent to be obtained and surgical procedure to be performed, with full information and facts regarding operative risks. However, there is no one single test that remains conclusively superior.     

Is thyroid frozen section too much for too little?

BACKGROUND: The role of frozen section (FS) in thyroid disease is controversial. The goal of this study was to identify a cohort of patients who may or may not benefit from FS. METHODS: Two hundred thirty-one patients who underwent thyroidectomy were evaluated in regard to fine-needle aspiration (FNA), FS, and the extent of surgery. RESULTS: In all, 155 patients underwent FNA, 140 patients underwent FS, and 103 patients had both. A final diagnosis of malignancy was obtained in 47 of 231 patients. FNA had a sensitivity of 50% and a specificity of 99%, and FS had a sensitivity of 50% and a specificity of 100% for diagnosing malignancy. Accounting for the clinical findings and FNA results, FS results altered the extent of thyroidectomy in 1 of 103 patients. CONCLUSIONS: The increased costs for the operative time and the pathologists needed to obtain routine FS are not supported with any substantial benefit in patient outcome.     

End-points of resuscitation how much is enough?

Fluid resuscitation after traumatic hemorrhage has historically been instituted as soon after injury as possible. Patients suffering from hemorrhagic shock may receive several liters of crystalloid, in addition to colloid solutions, in an attempt to normalize blood pressure, heart rate, urine output, and mental status, which are the traditional end-points of resuscitation. Current theory and recent investigations have questioned this dogma. Resuscitation goals may be different between when the patient is actively hemorrhaging, and once bleeding has been controlled. Newer markers of tissue and organ system perfusion may allow a more precise determination of adequate resuscitation.     

The safety of combined cardiac and vascular operations: how much is too much?

OBJECTIVE: The purpose of this study was to identify factors correlating with a poor outcome following combined cardiac and vascular procedures. METHODS: We reviewed 45 consecutive patients undergoing combined cardiac and vascular operations. These included cardiac/CEA (n=27), cardiac/AAA (n=13), cardiac/AAA/one other vascular reconstruction (n=4), and cardiac/renal artery bypass (n=1). Group I included all patients with no morbidity or mortality (n=41) and Group II included patients who died or suffered significant morbidity (stroke, renal failure) (n=4). RESULTS: Overall mortality was 4.4% (2/45). These two patients underwent cardiac surgery combined with two additional vascular procedures (cardiac/AAA/other). In patients undergoing cardiac/CEA or cardiac/AAA, there were no deaths and one stroke (contralateral to CEA). Group II had significantly decreased ejection fraction (39%+/-6% vs 52%+/-1%) and an increased number of procedures (2.75 vs 2.04). CONCLUSIONS: Combined cardiac surgery and vascular reconstruction can be performed safely. However, multiple vascular reconstructions or the presence of decreased ejection fraction increased operative risk.     

Observation of splenic trauma: when is a little too much?

A 12-year-old boy was treated conservatively for a grade II splenic laceration. On discharge, he was instructed to avoid contact sports, running, and strenuous physical activity. Thirty-eight days later, after diving off the side of a swimming pool, he had abdominal pain, nausea, and diaphoresis. On admission, he was hemodynamically unstable. Results of a diagnostic lavage showed gross blood. At laparotomy, a fractured spleen was found, and splenectomy was performed. He recovered without complication. This case questions the activity restrictions placed on patients with conservatively managed splenic trauma. Avoidance of only contact sports and heavy exertion may be inadequate.     

Complications of obstetric regional analgesia: how much information is enough?

Two hundred parturients who had received epidural analgesia during labour (100 in Melbourne, Australia and 100 in London, UK) were asked on the first postnatal day about their sources of antenatal information on pain relief in labour, their awareness of potential complications of epidural analgesia and the level of risk at which they would wish to be informed before consenting to a procedure. Sources of antenatal information were similar in the two countries although more women in Australia received information from an anaesthetist or obstetrician than in the UK, whilst more women in the UK received information from the media than in Australia. Knowledge of risks was also similar although the Australian subjects were more aware of infective complications while those in the UK were more aware of intravascular injection of local anaesthetic; these differences may reflect recent high-profile cases in the two countries. The preferred level of risk at which women wanted to be informed about a complication varied from 1:1 to 1:1,000,000,000 in all three centres. The majority of women considered that the benefits of epidural analgesia outweighed each of the potential complications. Women differ in their requirements for antenatal information about regional analgesia and its complications, with some wanting to know every complication, however rare. Anaesthetists should be flexible in their disclosure of information when obtaining consent for regional analgesia and consider the particular wishes of each patient rather than follow rigid centralised guidelines.