Historical basis for use of normal saline in wound care
Normal saline was neither developed nor designed for use as an irrigation solution. Reference to Pharmacopoeias published in the early 1900s reveals that normal saline was originally prepared for use as a blood volume expander by intravenous injection in the treatment of surgical shock following severe haemorrhage. In order to avoid haemolysis of red blood cells, the importance of using a solution having the same osmotic pressure as blood plasma was recognised. Hence a solution containing 0.9% w/v sodium chloride in water, being isotonic with blood plasma, became known as "normal saline solution" or "physiological salt solution".
It is interesting to note that in 1964, Robson [British Medical Journal i: 908 (1964)] drew attention to the fact that normal saline is neither normal nor physiological because it contains more sodium ions and more chloride ions (and no other ionic species) than are found in extracellular fluid and therefore that it can and does produce electrolyte imbalance.
Normal saline was adopted only quite recently as an irrigation solution in wound care simply because there became a need to replace Eusol and similar such chlorine-containing solutions following the recognition that these solutions were bio-incompatible.
Until the early 1980s, chlorinated lime / soda / potash solutions (Eusol / Dakin's / Eau de Javelle) had been used routinely for debridement of chronic ulcers, being originally developed at around the time of the Great War (1914-1918). In the late 1980s / early 1990s, evidence that Eusol solution can impair blood flow in the capillary circulation of granulation tissue in the rabbit ear chamber model of wound healing (and hence delays healing) was presented by David Leaper . Use of Eusol solution then fell rapidly out of favour [2,3]. A panel discussion and debate on the use and abuse of antiseptics at the 2nd European Conference on Advances in Wound Management (October 1992) focused almost entirely on the use/abuse of Eusol. As Eusol fell out of use, normal saline took its place simply by default.
In the mid 1990s / early 2000s, tap water was identified as a potential alternative to normal saline for wound irrigation. Following preliminary experiments in healthy animals, clinical studies were undertaken comparing outcomes following the use of tap water or normal saline for irrigation of simple traumatic wounds and lacerations in hospital emergency departments. Rates of healing were assessed in terms of infection rates; infection rates were found not to increase following irrigation with tap water [4,5]. Although these studies were not done in chronic ulcer patients and did not involve repetitive irrigation of open, non-healing wounds over periods of several weeks or months, tap water was subsequently vociferously promoted as a cheap alternative to normal saline by Brian Gilchrist and others for the simple irrigation / debridement of chronic ulcers.
So, the background scientific literature clearly points to the conclusion that normal saline is bio-incompatible. As is commonly recounted in discussions of the history of medicine, it has often been the case that we have recovered from our illnesses and injuries despite rather than because of the treatment we have received. Our bodies have a remarkable ability to tolerate adverse conditions, but it does not therefore follow that we should continue to use treatments that have been identified as having a tendency to cause adverse outcomes. This is the philosophy that underlies the development of virtually every new drug / treatment. But, can we improve on normal saline? To do this, we first have to understand why normal saline is bio-incompatible. We then have to contemplate ways in which we might minimise this bio-incompatibility by design.
The effects of several antiseptic agents on granulation tissue were studied using rabbit ear chambers as models of the healing wound. This enabled us to study dynamically the action of these agents on the microcirculation of the wound. All the agents tested caused some adverse effect, but in the cases of hypochlorite antiseptics Eusol and Chloramine T, blood flow in the capillary circulation of the granulation tissue ceased and the process of repair was subsequently delayed. A laser Doppler flowmeter was used to measure these changes in local perfusion which reflected the toxic effects seen on microscopy of the ear chamber.
Despite a wide range of new wound care products, nurses continue to use sodium hypochlorite to treat wounds. This article explores the potential dangers of this practice.
Hypochlorite solutions have been an issue of controversy for many years. Research has highlighted their harmful effects and yet doctors and nurses continue to use them. This article will review the literature both for and against the use of hypochlorite solutions and will examine alternative wound dressings.
4. Angeras MH, Brandberg A, Falk A, and Seeman T. Comparison between sterile saline and tap water for the cleaning of acute traumatic soft tissue wounds. European Journal of Surgery 158(6-7): 347-350 (1992)
OBJECTIVE―To find out if there were any differences in infection rates if acute traumatic soft tissue wounds were cleaned with tap water instead of sterile saline. DESIGN―Randomised study. SETTING―Emergency department at one city hospital. SUBJECTS―705 consecutive patient with soft tissue wounds less than six hours old that did not penetrate a viscus, cavity, or joint and could be treated by primary suture. INTERVENTIONS--Randomly allocated to have the wound cleaned with either sterile saline or tap water in addition to debridement. MAIN OUTCOME MEASURE―Rate of wound infection, the presence of which was indicated by pus in the wound and prolonged healing. RESULTS―The infection rate in wounds cleaned with sterile saline was 10.3% compared with 5.4% in wounds cleaned with tap water (p < 0.05). Infected wounds were significantly larger than uninfected ones (p < 0.05) and more likely to be located on a lower extremity (p < 0.05). There were no microbiological differences between the two groups, and no bacterial species grown from tap water was subsequently grown from an infected wound. CONCLUSION―Sterile saline should be replaced by tap water for the cleaning of acute traumatic superficial soft tissue wounds.
OBJECTIVE: To compare the infection rates in pediatric wounds irrigated with sterile saline vs. running tap water. METHODS: A prospective, randomized trial conducted in an urban public hospital pediatric emergency department (PED). Water pressure and flow rates were measured from all taps and were comparable to published data. Cultures of tap water were obtained by standard techniques at 4-month intervals. Patients 1-17 years presenting to the PED with a simple laceration requiring repair with glue, sutures, or staples were eligible. Exclusion criteria included immunocompromise, complicated laceration, or current use of or need for antibiotics for wound prophylaxis. Saline irrigation was performed using standard technique on even days. A protocol using running tap water for irrigation on odd days was developed to ensure uniform volume, time, and standard pressure. Demographic and wound characteristic data were recorded. Wounds were anesthetized and closed in standard fashion. Patients were asked to return to the PED in 48-72 hours for wound evaluation. Wound infection was recorded utilizing a previously reported wound infection grading scale. RESULTS: Four hundred twenty-one patients with 444 wounds were eligible. Thirty-five patients refused to participate, and 26 patients with 27 wounds were lost to follow-up. Three hundred sixty patients with 382 wounds comprised the final sample (209 wounds in the saline group and 173 wounds in the tap water group). There was no significant difference between the groups in terms of demographics, wound characteristics, wound type, or repair method. There was no difference in the wound infection rate between the sterile saline group (3.35%) [95% CI 1.4%, 6.8%] and the running tap water group (3.46%) [95% CI 1.3%, 7.4%] (p = 0.95). CONCLUSIONS: In our sample, there was no difference in the infection rate in wounds irrigated with tap water or saline. Tap water may be an effective alternative to sterile saline for wound management in children.
Authors report endothelial cell death in tissue culture after a 5 minute exposure to distilled water.
Rat femoral vessels were clamped and perfused internally in situ for 30 minutes using five different irrigating solutions (normal saline, lactated Ringer's solution, Normosol R, pH 6.2 and 7.4, and glutathione buffered Ringer's solution). After the blood flow was reestablished, the vessels were excised at 30 minutes or 48 hours after irrigation and were sectioned longitudinally for light microscopy. Normal saline consistently produced the most severe damage. None of the agents tested proved biochemically atraumatic, and none were consistently superior to lactated Ringer's solution. Endothelial hyperplasia and platelet deposition were unexpectedly frequent findings at 48 hours.
OBJECTIVE: The purpose of this study was to determine the effects of phosphate-buffered saline (PBS), sterile tap water, normal saline, and Ringer's lactate on wound healing in an in vitro model. STUDY DESIGN: The effects of PBS, sterile tap water, normal saline, and Ringer's lactate on a primary line of canine embryonic fibroblasts were determined. ANIMALS OR SAMPLE POPULATION: A primary line of canine embryonic fibroblasts. METHODS: The effects of the various lavage solutions were determined by (1) vital staining of the treated cells with a 0.5% trypan blue solution, (2) evaluation of the amount of lactate dehydrogenase released by the treated cells, and (3) cytopathologic evaluation of hematoxylin and eosin-stained monolayers of treated canine fibroblasts. The cells were exposed to the lavage treatments for the following time intervals: 0.5 minute, 1 minute, 2.5 minutes, 5 minutes, and 10 minutes. PBS was used as the control. RESULTS: Sterile tap water significantly damaged canine fibroblasts at all time intervals (P = .05). This was attributed to the alkaline pH, hypotonicity, and presence of numerous cytotoxic trace elements in the tap water used. Cytotoxic effects were noted in fibroblasts after 10 minutes' exposure to normal saline; this may be because of the acidic pH of normal saline and lack of a buffering system. Ringer's lactate did not induce any significant fibroblast injury. CONCLUSIONS: PBS and Ringer's lactate do not induce any significant fibroblast injury, whereas normal saline and sterile tap water cause mild and severe cytotoxic effects in vitro. CLINICAL RELEVANCE: Further clinical investigation is indicated to establish whether Ringer's lactate is the wound lavage solution of choice compared with normal saline. Sterile tap water may cause considerable fibroblast injury.
9. Wang T, Heimbürger O, Qureshi AR, Waniewski J, Bergström J, and Lindholm B. Physiological saline is not a biocompatible peritoneal dialysis solution. International Journal of Artificial Organs 22(2): 88-93 (1999)
We have previously demonstrated that daily exposure to dialysis fluid results in significantly increased peritoneal lymphatic flow. In this study, we investigated if daily intraperitoneal infusion of saline (isotonic, glucose free) could cause similar changes. METHODS: Sixteen male SD rats received daily infusion (i.p.) of 20 ml saline for ten days (Saline group). Twenty-four hours after the last infusion, a 4 hour dwell study using 25 ml 3.86% glucose dialysis solution with frequent dialysate and blood sampling was done in each rat as well as in rats which did not receive daily infusion (Control, n=8). Radiolabeled human albumin (RISA) was added to the solution as an intraperitoneal volume marker. Radioactivity, glucose, urea, sodium, and potassium were measured for each sample. In a separate study, the RISA absorption to peritoneal tissue was also determined. RESULTS: The net ultrafiltration was significantly decreased in the daily infusion group (p<0.05). However, the apparent volume at 3 minutes of the dwell was markedly increased; this was due to a significant increase in the RISA binding (1.5-12.0% in the Saline group vs. 0.45-1.12% in the Control group) to peritoneal tissues as assessed by measurement of RISA recovery at 3 min of the dwell. This resulted in a significant overestimation both of the intraperitoneal volume (IPV) at 3 min and the (apparent) fluid absorption rate (as estimated by the transport of RISA out of peritoneal cavity): 0.087±0.026 ml/min in the Saline group vs. 0.052±0.007 ml/min in the Control group, p<0.001. The direct lymphatic flow as estimated by the clearance of RISA to plasma (which should not be affected by the RISA binding) also increased markedly (0.021±0.005 ml/min in the Saline group vs. 0.008±0.001 ml/min in the control group). There was no significant difference in the D/P values for small solutes (urea, sodium, potassium, urate) and D/D0 for glucose between the two groups. CONCLUSIONS: 1) Daily infusion of physiological saline into peritoneal cavity may increase the peritoneal lymphatic flow; 2) The significant (apparent) increase in IPV shortly after infusion may suggest increased RISA binding to peritoneal tissues (which may be related to the damage of the tissues, and results in overestimation of the peritoneal fluid absorption rate); 3) Saline is not a biocompatible peritoneal dialysis solution, and should therefore not be used as a control or flush solution.
10. Polubinska A, Breborowicz A, Staniszewski R, and Oreopoulos-Dimitrios G. Normal saline induces oxidative stress in peritoneal mesothelial cells. Journal of Pediatric Surgery 43(10): 1821-1826 (2008)
BACKGROUND: Peritoneal adhesions are the most common complication of the abdominal surgery. Normal saline is frequently used to rinse the peritoneal cavity during abdominal surgery, although there is no well-established data describing effect of such procedure on the process of formation of peritoneal adhesions. METHODS: Effect of 0.9% NaCl solution on viability, oxidative stress, and fibrinolytic activity of human peritoneal mesothelial cells maintained in in vitro culture was evaluated. RESULTS: Exposure of mesothelial cells to 0.9% NaCl induces oxidative stress, derangement of their structure with subsequent increased release of tissue factor (+75%) and plasminogen activator inhibitor-1 (+19%), and simultaneous suppression of tissue plasminogen activator release (-39%). In effect, ration tissue plasminogen activator/plasminogen activator inhibitor-1 was reduced in 0.9% NaCl-treated cells by 50%. Pretreatment of cells with precursor of glutathione synthesis: L-2-oxothiazolidine-4-carboxylic acid prevented these changes. CONCLUSIONS: Oxidative stress in the peritoneal mesothelium caused by 0.9% NaCl activates their procoagulant activity and impairs fibrinolytic properties of these cells. These effects disqualify 0.9% NaCl as a rinsing solution during abdominal surgery.
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