Introduction
This study aims to identify the association between perioperative hypothermia and surgical site infection (SSI). I will begin by conducting some research to critically analyze evidenced-based data collected. My objective is to contribute some measures in my department in the management and prevention of perioperative hypothermia, thus reducing SSI in all surgical patients. Maintaining a core temperature is essential to prevent complications from hypothermia. WHO (2018) advised warming equipment should be utilized during surgical procedures to keep the patient’s body warm and reduce SSI. Hypothermia happens when the core body temperature drops below 36’C and a patient’s susceptibility to infection increases (Wicker and Dalby, 2017). Wound infection is the most common cause of wound healing complications (NICE, 2008). SSI is an infection that occurs as a complication after surgery in the area where the surgery was performed (CDC 2019). SSI has been found to account for up to 20% of all infections in healthcare (Anderson et al., 2014, p. 605). SSI remains a serious problem linked to mortality and morbidity and putting a strain on healthcare resources (NICE 2020). Thus, effective prevention and management of perioperative hypothermia is essential to reduce SSI in surgical patients and achieve better patient outcomes.
Review of Findings
Research results on the relationship between perioperative hypothermia and SSI are contradictory. These inconsistent findings have sparked a debate about whether perioperative hypothermia is linked to an increased risk of SSI in surgical patients. In their meta-analysis, Bu et al. (2019) have concluded that there is no association between perioperative hypothermia and SSI. However, the number of randomized controlled trials (RCTs) used in this research is minimal, which makes the results of the study inconclusive. As a consequence, the RCTs pooled OR (Odd Ratio) results have minimal strength.
However, their observational studies found no link between perioperative hypothermia and the risk of SSI in the postoperative population. Melton et al. (2013) investigated the relationship between intraoperative hypothermia and SSI in 1008 patients undergoing colorectal surgery from 2008 to 2013, finding a 17.4% (n=175) incidence rate for this type of infection and no link between temperature measurements and SSI. Melton et al. (2013) investigated the relationship between intraoperative hypothermia and SSI in 1008 patients undergoing colorectal surgery from 2008 to 2013, finding a 17.4% (n=175) incidence rate for this type of infection and no link between temperature measurements and SSI. Baucom et al. (2013) found no relation between perioperative hypothermia and 30-day SSI in patients who had a ventral hernia repaired. Their recent study also looked at the connection between perioperative hypothermia and SSI in patients who had elective segmental colectomy, using reliable perioperative temperature measurement and four definitions of hypothermia.
Temperature did not predict SSI in multivariable analysis, regardless of how hypothermia was defined, and it was the least influential factor in each model evaluated. The variable predicting SSI was body mass index (BMI) (Baucom et al., 2015). Siddiqiui et al. (2020) conducted a prospective cohort analysis of adult patients who underwent elective laparotomy with a 30-day follow-up to detect SSI, however their findings failed to reveal a statistically significant link between hypothermia and SSI. The study comprised a total of 183 patients who met the eligibility requirements. In the perioperative hypothermia cohort, 90 patients (49%) had perioperative hypothermia, while in the normothermia cohort, 93 patients (51%) remained normothermic during the surgical phase. The patients were 49.77+/-14 years old on average. Females made up over two-thirds of the participants (63.9 percent). Hypothermia patients were substantially older and had a lower BMI.
In the normothermic cohort, the proportion of female patients was also much greater. With a p-value of 0.867, the rate of SSI was identical in both groups (10 percent versus 10.8 percent). Hypothermia and SSI were similarly found to have no significant relationship in multivariable regression analysis. Hypothermia is a frequent multifactorial event, and age was a critical factor for the occurrence of hypothermia (Peixoto et al, 2020). Patients who develop hypothermia were considerably older and had a lower BMI in the study of Siddiqiui et al. (2020), however increased BMI was strongly related with SSI in all four logistic regression models in the study of Baucom et al. (2015).
Despite advances in surgical methods, SSI is still one of the most common surgical complications. According to Ribeiro et al. (2020), perioperative hypothermia can increase the risk of SSI. The team did a prospective cohort research with 484 patients from a prominent private hospital. To investigate the effect of this exposure on SSI, crude and adjusted models for hypothermia indicators were created. Perioperative hypothermia was discovered to be an independent risk factor for SSI. According to the attributable fractions to the exposed, more than 40% of SSI cases could be averted if the main exposure of interest (perioperative hypothermia) could be avoided during surgical anaesthetic operations.
The prevention of SSI requires consideration of multiple contributing factors by perioperative practitioners (Korol et al., 2013). Health practitioners must take appropriate efforts to sustain patients’ normothermia during the perioperative phase, resulting in improved care and surgical safety. Half of all SSIs are thought to be prevented using evidence-based measures (Berrios-Torres, 2017). Future research initiatives that use a prospective design can help to strengthen the consistency of the findings in order to gain a better grasp of the SSI problem on a global scale (Rebeiro et al., 2020). Hypothermia may play a role in the development of SSI, according to Cengiz et al. (2021), depending on the degree of hypothermia, the kind and duration of operation, anaesthetic type, and patient characteristics. Severe hypothermia (below 35.0°C) can increase the risk of SSI (Cengiz et al., 2021).
Researchers discovered that patients receiving emergency post-traumatic surgical treatments had the highest prevalence of SSI in their review. SSI development may have occurred during emergent trauma laparotomies, contaminated open wounds, the patient’s critical state, and various factors such as blood loss or procedure time. In a systematic review and meta-analysis of SSI epidemiology, it was discovered that 52.7 percent of patients with infected wounds and 24.0 percent of patients with contaminated wounds had SSI. Patients undergoing elective segmental colectomy and gastrointestinal system surgery under general anaesthesia had a high incidence of SSI, according to the research they conducted. Studies on the impact of longer procedures on SSI development have yielded mixed results. Longer operations were reported to enhance the chance of SSI development by some researchers, whereas one study found no influence of operating duration on the formation of SSI. These variances could be related to hospital variability, surgeon and surgical team member skills, patient demographics, sample size, and surgical operation kinds.
The most important finding of the study by Seamon et al. (2012) is that intraoperative hypothermia below 35’C had a substantial impact on SSI, and that a single temperature measurement below 35’C during a trauma laparotomy doubled the chance of SSI. The study included 524 patients ranging in age from 18 to 88 years old who had a trauma laparotomy regardless of the aetiology of damage. A “cut-point” study was used to determine which intraoperative nadir temperature value is the most predictable for SSI development. SSI patients had a longer operative time and a lower mean temperature nadir (34.5’C +/-1.0’C versus 35’C +/-1.1’C). Intraoperative temperature of 35°C was shown to be the best model fit and consequently the most predictive of SSI development. According to the findings, intensive intraoperative warming will help prevent SSI and enhance outcomes after trauma laparotomy. Hypothermia during surgery lowers peripheral circulation, increasing the risk of SSI.
Hypothermia in patients was associated with a higher rate of postoperative complications when compared with normothermic patients (Akers et al., 2019). Hypothermia is associated with vascular complications; vasoconstriction is thought to alter protein metabolism resulting in a decrease in subcutaneous oxygen tension. These effects have shown an increase in surgical wound infection (Scott, 2012). The sympathetic nervous system is activated by hypothermia, which results in a rise in serum norepinephrine, which causes peripheral vasoconstriction. Vasoconstriction reduces the amount of oxygen delivered to the surgical site, resulting in lower oxygen tension and relative wound hypoxia. Hypoxia in the wound then affects the immune system. During surgical procedures, neutrophils are the primary line of defence against bacterial infection. Hypothermic patients’ neutrophils require oxygen, which is depleted in hypothermic individuals. Therefore, intraoperative normothermia in patients having surgical procedures should be carefully managed (Seamon et al., 2012).
The differences in these results can be attributed to the diverse study designs, the year in which the studies were conducted, and the small number of cases recruited. If the sample size is too small, it will either fail to detect major effects that are genuinely present in a population (false negative results, also known as Type 2 error) or may provide a false positive result by chance (Type 1 errors). To avoid these two inaccuracies, it is critical that the researchers calculate the sample size required (Bowers et al 2021). According to some studies, prewarming can help prevent SSI by maintaining circulation and oxygen transport at the incision while also preserving the immune response. However, research by Baucom et al. (2013) found that perioperative heat has no effect on infection growth. A total of seven RCTs were included in the study conducted by Zheng et al. (2020), and the results showed that prewarming could reduce the incidence of SSI by 40%. The thermoregulatory system is inhibited by general anaesthesia, which prevents cellular metabolism and causes the body to lose its ability to generate heat (Knaepel, 2012).
Hypothermia is caused mostly by the cool temperature maintained in most operating rooms, other causes include exposure of an open body cavity during surgery, use of cold irrigation solutions, and skin preparations. It is the most preventable complications in surgery (Wicker and Dalby, 2017). Pre-operative warming for at least 20 minutes has been advocated by Zheng et al to lower the occurrence of intraoperative hypothermia. Their meta-analysis also revealed that pre-warming 15-30 minutes ahead of time may be preferable than pre-warming 2 hours ahead of time. According to their research, warming methods have a considerable impact on the occurrence of SSI. The systematic selection and appraisal of the primary studies according to an approve protocol means that the bias is minimised. Smaller studies, which are all too common in some topic areas, may show a trend towards positive impact but lack statistical significance. However, when data from several small studies are summed mathematically in a process called meta-analysis, the combined data may produce a statistically significant finding. Systematic review can help resolve contradictory findings among different studies on the same question if the systematic review has been properly conducted, the results are likely to be robust and generalised. On the negative side, systematic review can replicate and magnify flaws in the original studies-misleading (Greenhalg 2019).
Hypothermia is caused mostly by the cool temperature maintained in most operating rooms, other causes include exposure of an open body cavity during surgery, use of cold irrigation solutions, and skin preparations. It is the most preventable complications in surgery (Wicker and Dalby, 2017; Greenhalgh, Verboon, and Patel, 2021);. But when data from several small studies are summed mathematically in a process called meta-analysis, the combined data may produce a statistically significant finding (Pigott and Polanin, 2020). Systematic review can help resolve contradictory findings among different studies on the same question if the systematic review has been properly conducted, the results are likely to be robust and generalised.
On the negative side, systematic review can replicate and magnify flaws in the original studies, making them misleading (Greenhalg, Thorne, and Malterud, 2018). Knaepel (2012) states that hypothermia is preventable if frequent temperature monitoring and early warming therapy interventions are initiated core body temperature is regulated in the conscious patient by the thermoregulatory system. O’Hara et al. (2018) state that hypothermia may increase susceptibility to surgical wound infection by prompting subcutaneous vasoconstriction and consequent tissue hypoxia. Hypothermia increase SSI rates by directly impairing neutrophil function. Maintenance of perioperative hypothermia is therefore vital when working to prevent SSI (Guilliamo, 2017). Therefore, hypothermia must be prevented using appropriate measures. The rest of the research is predominantly cohort studies, which based their findings on observational data from patient samples, with minor differences in types of surgery and sample sizes.
The thermoregulatory system in the conscious patient regulates core body temperature. The hypothalamus serves as a thermostat, increasing or reducing body temperature in response to changes in temperature. The thermoregulatory system is inhibited by general anaesthesia, which prevents cellular metabolism and causes the body to lose its ability to generate heat (Knaepel 2012). Hypothermia is caused mostly by the cool temperature maintained in most operating rooms, other causes include exposure of an open body cavity during surgery, use of cold irrigation solutions, and skin preparations. It is the most preventable complications in surgery (Wicker and Dalby, 2017). Pre-operative warming for at least 20 minutes has been advocated by Zheng et al. (2020) to lower the occurrence of intraoperative hypothermia. Their meta-analysis also revealed that pre-warming 15-30 minutes ahead of time may be preferable than pre-warming 2 hours ahead of time. According to their research, warming methods have a considerable impact on the occurrence of SSI.
Inadvertent hypothermia in surgical patients can be avoided. The perioperative nurse’s knowledge and abilities can help to avoid it from happening and having negative implications for the patients (Giulliano and Hendricks 2017). According to Melton et al. (2013) although rewarming did not reduce SSI rates, it has been linked to benefits such as lower complication rates in earlier research, including numerous rigorous trials. Therefore, the study does not rule out rewarming as a standard of treatment. Although, Bu et al. (2019) and Baucom et al. (2015) also found no link between hypothermia and SSI, they acknowledged that sustaining preoperative hypothermia is crucial for other physiologic reason and since hypothermia has been linked to other negative outcomes. However, in order to avoid waste in the healthcare system, the ideal timing of active warming in postoperative patients should be actively considered.
Conclusion
This essay has presented a comprehensive analysis of the findings from the studies regarding the implications of hypothermia and SSI. SSI constitutes a problem since it is connected significant mortality and morbidity, in addition to being the cause of extra expenses. However, some inconsistencies have been found in the results of studies. Therefore, this topic should be studied more in greater detail. However, given the importance of the consequences of SSI for people with comorbidities and those undergoing recovery from surgery, the author of this study recommends practices to prevent hypothermia such as maintaining a warmer room temperature, using extra blankets, and regular temperature monitoring. More RCT’s are likely needed that might be able to prove a direct link between additional risk factor reasons for hypothermia and SSI. Practioners could adjust some hypothermia prevention procedures where they are not required and pay more attention to patients at higher risk situations to save health care costs. As the first surgical assistant, I will need to consider the specified information as essential to further advance my practice and introduce tools for reducing the threat of hypothermia as a possible factor for SSI development as well as the cause of other health issues.
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