Hypothermia and surgery: immunologic mechanisms for current practice

Enhanced recovery after surgery programs hasten recovery after colorectal resections

Colorectal resection was traditionally associated with significant morbidity and prolonged stay in hospital. Laparoscopic colorectal resection was first described in 1991 as a minimally invasive form of colorectal surgery. It was later on assessed by multiple randomized controlled trials and meta-analysis and was found to be associated with a faster recovery, lower complication rates and a shorter stay in hospital compared with open resection. To assess the effect of enhanced recovery after surgery (ERAS) program on postoperative length of stay after elective colorectal resections, a literature review was conducted, supplemented by the results of 111 ERAS colorectal resections at regional NWS Hospital using a protocol based on the Fast Track approach described by Kehlet in 1999. ERAS has been shown to improve postoperative recovery, reduce length of stay and enhance early return to normal function when compared with traditional colorectal surgical protocols. The role of laparoscopic surgery in colorectal resections within a fast-track (ERAS) program is controversial. The current evidence suggests that within such a program, there is no difference between laparoscopic and open colorectal surgery in terms of postoperative recovery rates or length of hospital stay.

Heated CO(2) with or without humidification for minimally invasive abdominal surgery

BACKGROUND

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times.

OBJECTIVES

To determine the effect of heated gas insufflation on patient outcomes following minimally invasive abdominal surgery.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (PubMed), EMBASE, International Pharmaceutical Abstracts (IPA), Web of Science, Scopus, www.clinicaltrials.gov and the National Research Register were searched (1956 to 14 June 2010). Grey literature and cross-references were also searched. Searches were limited to human studies without language restriction.

SELECTION CRITERIA

All included studies were randomized trials comparing heated (with or without humidification) gas insufflation with cold gas insufflation in adult and pediatric populations undergoing minimally invasive abdominal procedures. Study quality was assessed in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. The selection of studies for the review was done independently by two authors, with any disagreement resolved in consensus with a third co-author.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, data extraction and methodological quality assessment of the trials were performed by the authors. Data from eligible studies were collected using data sheets. Results were presented using mean differences for continuous outcomes and relative risks with 95% confidence intervals for dichotomous outcomes. The estimated effects were calculated using the latest version of RevMan software. Publication bias was taken into consideration and funnel plots were compiled.

MAIN RESULTS

Sixteen studies were included in the analysis. During laparoscopic abdominal surgery, no effect on postoperative pain nor changes in core temperature, morphine consumption, length of hospitalisation, lens fogging, length of operation or recovery room stay were associated with heated compared to cold gas insufflation with or without humidification.

AUTHORS' CONCLUSIONS

The study offers evidence that during laparoscopic abdominal surgery, heated gas insufflation, with or without humidification, has minimal benefit on patient outcomes.

In vitro study of variables relevant to perioperative care of the surgical patient: glucose, osmolarity, and rewarming

BACKGROUND

We sought to determine the effects of altering osmolarity and the reversibility of the detrimental immunologic effects of hypothermia on human monocyte HLA-DR surface expression and reactive oxygen species (ROS) formation.

STUDY DESIGN

The effects of altering osmolarity on HLA-DR surface expression and ROS formation were assessed using lipopolysaccharide (LPS)-treated samples treated with either saline, glucose, or mannitol, incubated at 37°C for 2 hours. HLA-DR surface receptor expression and ROS formation were determined after incubation. The effects of the reversibility of hypothermia were measured by incubating LPS-treated samples at 34°C, 37°C, and 40°C for 1 hour. The samples were subsequently rewarmed at 40°C for 1 and 2 hours. The effects of rewarming on HLA-DR surface receptor expression and ROS formation were reassessed.

RESULTS

In the osmolarity experiments, there was a 49% decrease in ROS formation in samples treated with mannitol as compared with saline and glucose. Alterations of osmolarity had no significant effect on HLA-DR surface expression. In the rewarming experiments, rewarming for either 1 or 2 hours abolished any significant differences in HLA-DR surface expression and ROS formation between samples preincubated at the different temperatures.

CONCLUSIONS

The presumed inert mannitol was found to significantly decrease ROS formation, but had no effect on HLA-DR surface expression. In addition, the effects of hypothermia on HLA-DR surface expression or ROS formation may be better reversed within 2 hours than in 1 hour.

A situational overview of surgical quality and safety in 2010

BACKGROUND

Surgical safety and quality initiatives have now moved to the front of the agenda for contemporary surgery.

METHODS

Sixty-two surgical specialists began to study quality and cost control in 1998, and those efforts grew into a Centers for Medicare and Medicaid Services-funded pilot study of the Surgical Care Improvement Project in 2004. Subsequent symposia and studies evolved.

RESULTS

A greater awareness of the issues and methods for meaningful improvement of surgical safety in nearly 25,000 specialty surgeries have been described in numerous peer-reviewed publications.

CONCLUSIONS

Surgeon-initiated efforts have led to marked improvements in multiple specialties and in many small and large hospitals and academic training centers.

Effect of major abdominal surgery on the host immune response to infection

PURPOSE OF REVIEW

The present review summarizes key studies on the effects of major abdominal surgery on the host response to infection published during the last 18 months.

RECENT FINDINGS

Surgical trauma causes stereotyped systemic proinflammatory and compensatory anti-inflammatory reactions. It is leukocyte reprogramming rather than general immune suppression. The list of recent findings is long. Preoperative infectious challenge was found to increase survival. Obesity is associated with increased production of interleukin-17A in peritonitis. Abdominal surgery alters expression of toll-like receptors (TLRs). The acute phase reaction down-regulates the transcription factor carbohydrate response element binding protein. Myosin light chain kinase activation is a final pathway of acute tight junction regulation of gut barrier and zonula occludens 1 protein is an essential effector. The brain is involved in regulating the immune and gut system. Elimination of lipopolysaccharide is challenging. Th1/Th2 ratio is lowered in patients with postoperative complications. Cholinergic anti-inflammatory pathways can inhibit tissue damage. The new substance PXL01 prevents adhesions. Postoperative infection causes incisional hernias. Hypothermia reduced human leukocyte antigen DR surface expression and delayed tumor necrosis factor clearance. Systems biology identified interferon regulatory factor 3 as the negative regulator of TLR signaling. Protective immunity could contribute defeating surgical infections.

SUMMARY

Systemic inflammation is the usual response to trauma. All organs seem to be involved and linked up in cybernetic systems aiming at reconstitution of homeostasis. Although knowledge is still fragmentary, it is already difficult to integrate known facts and new technologies are required for information processing. Defining criteria to develop therapeutic strategies requires much more insight into molecular mechanisms and cybernetics of organ systems.

Article Commentary: Optimizing Surgical Care: A Contemporary Assessment of Temperature, Oxygen, and Glucose

Factors such as temperature, oxygen, and glucose have recently been implicated in the development of surgical sepsis by either promoting or attenuating protective components of the innate immune response. Reducing infective sequelae and the improvement of the quality of care of surgical patients is a top practice priority today. These factors and their associated effects are discussed through the examination of recent clinical and scientific studies to provide an up-to-date evidence-based review.

Glucose and surgical sepsis: a study of underlying immunologic mechanisms

BACKGROUND

Early clinical trials investigating the role of tightly controlled glucose levels showed marked benefit in survival of critically ill patients. However, a recent meta-analysis and large randomized controlled trial have failed to reproduce the benefit, showing instead substantially increased risk of dangerous hypoglycemia. We sought to investigate the effects of varying glucose concentrations on previously tested, prognostically significant, innate immune parameters, to define any potential effects of glucose at the cellular level.

STUDY DESIGN

After formal approval and informed consent, venous blood samples were collected from young healthy volunteers. Up to 11 corresponding (same-subject) samples were incubated at 100, 350, or 600 mg/dL glucose concentrations and analyzed to determine human leukocyte antigen-DR surface receptor expression, cytokine release, phagocytic capacity, and formation of reactive oxygen species. Data are presented as mean +/- SEM.

RESULTS

After incubation, the change in human leukocyte antigen-DR mean channel fluorescence from resting baseline values in lipopolysaccharide-stimulated monocytes was not significantly different between 100, 350, and 600 mg/dL (1,749 +/- 110; 1,748 +/- 120; and 1,725 +/- 96, respectively; p = 0.89). Tumor necrosis factor-alpha concentrations were significantly lower for samples incubated at higher glucose concentrations (179 +/- 50 pg/mL, 125 +/- 30 pg/mL, and 107 +/- 29 pg/mL; p < 0.05). The phagocytic capacity of the innate immune system was marginally enhanced by glucose. However, the formation of reactive oxygen species was markedly impaired by rising glucose (55% to 66% impairment; p < 0.05).

CONCLUSIONS

Increasing glucose concentrations exert considerable opposing effects on several well-established innate immunologic processes. The opposing findings might contribute to recent clinical controversies. Physician judgment and experience are essential to imminent treatment of critically ill and perioperative surgical patients.