Detrimental effects of hypothermia: a systems analysis

An injectable refrigerated hydrogel for inducing local hypothermia and neuroprotection against traumatic brain injury in mice

BACKGROUND

Hypothermia is a promising therapy for traumatic brain injury (TBI) in the clinic. However, the neuroprotective outcomes of hypothermia-treated TBI patients in clinical studies are inconsistent due to several severe side effects. Here, an injectable refrigerated hydrogel was designed to deliver 3-iodothyronamine (T1AM) to achieve a longer period of local hypothermia for TBI treatment. Hydrogel has four advantages: (1) It can be injected into injured sites after TBI, where it forms a hydrogel and avoids the side effects of whole-body cooling. (2) Hydrogels can biodegrade and be used for controlled drug release. (3) Released T1AM can induce hypothermia. (4) This hydrogel has increased medical value given its simple operation and ability to achieve timely treatment.

METHODS

Pol/T hydrogels were prepared by a low-temperature mixing method and characterized. The effect of the Pol/T hydrogel on traumatic brain injury in mice was studied. The degradation of the hydrogel at the body level was observed with a small animal imager. Brain temperature and body temperature were measured by brain thermometer and body thermometer, respectively. The apoptosis of peripheral nerve cells was detected by immunohistochemical staining. The protective effect of the hydrogels on the blood-brain barrier (BBB) after TBI was evaluated by the Evans blue penetration test. The protective effect of hydrogel on brain edema after injury in mice was detected by Magnetic resonance (MR) in small animals. The enzyme linked immunosorbent assay (ELISA) method was used to measure the levels of inflammatory factors. The effects of behavioral tests on the learning ability and exercise ability of mice after injury were evaluated.

RESULTS

This hydrogel was able to cool the brain to hypothermia for 12 h while maintaining body temperature within the normal range after TBI in mice. More importantly, hypothermia induced by this hydrogel leads to the maintenance of BBB integrity, the prevention of cell death, the reduction of the inflammatory response and brain edema, and the promotion of functional recovery after TBI in mice. This cooling method could be developed as a new approach for hypothermia treatment in TBI patients.

CONCLUSION

Our study showed that injectable and biodegradable frozen Pol/T hydrogels to induce local hypothermia in TBI mice can be used for the treatment of traumatic brain injury.

Preoperative warming and undesired surgical and anesthesia outcomes in pediatric spinal surgery-a retrospective cohort study

BACKGROUND

Underbody forced air warming is a method commonly used for intraoperative temperature maintenance in children. We previously reported that preoperative forced air warming of children undergoing spinal surgery substantially reduces the incidence and duration of intraoperative hypothermia (<36°C).

OBJECTIVE

The aim of this study was to evaluate the effects of preoperative warming before spinal deformity surgery on surgical site infection rate, length of hospitalization, and bleeding (estimated blood loss and incidence of cell salvaged and/or allogeneic packed red blood cell transfusions).

METHODS

Demographic, anesthetic, and surgical data of all patients who underwent spinal deformity surgery between December 2009 and December 2012 were obtained by retrospective chart review. Temperature data were abstracted from an existing repository; the incidence and duration of hypothermic episodes were identified. For each outcome, logistic regression models and propensity score analysis were used to estimate the effect of prewarming, adjusted for potential confounders. The issue of missing data was handled by a multiple imputation method. Data from 334 procedures were used in modeling and propensity score stratification.

RESULTS

Adjusted odds ratios for the effects of prewarming were 0.47 (95% CI 0.15-1.49) for surgical site infections; 0.89 (95% CI 0.55-1.41) for cell salvaged blood transfusion; 0.43 (95% CI 0.22-0.83) for allogeneic packed red blood cell transfusion; and 1.24 (95% CI 0.77-1.99) for a length of hospitalization >6 days. Adjusted mean decrease in estimated blood loss for prewarming was 72 (95% CI -29 to 173) ml.

CONCLUSION

In this study, prewarming was associated with a reduction in allogeneic packed red blood cell transfusion. However, no causal relationship between prewarming and reduced allogeneic blood transfusion should be assumed. Prewarming was not associated with reductions in estimated blood loss, length of hospitalization, or the incidence of surgical site infection.

Effect of irrigation fluid temperature on core temperature and hemodynamic changes in transurethral resection of prostate under spinal anesthesia

Background:

Hypothermia is a frequent observation in elderly males undergoing transurethral resection of prostate (TURP) under spinal anesthesia. The use of irrigating fluids at room temperature results in a decrease body temperature. Warmed irrigating solutions have shown to reduce heat loss and the resultant shivering. Such investigation was not much tried in low resource settings.

Aim:

To compare the resultant change in core temperature and hemodynamic changes among patients undergoing TURP surgery under spinal anesthesia using warm and room temperature irrigation fluids.

Settings and Design:

Randomized prospective study at a tertiary care center.

Methods:

This study was conducted on 40 male patients aged 50-85 years undergoing TURP under spinal anesthesia. Of which, 20 patients received irrigation fluid at room temperature 21°C and 20 patients received irrigation fluid at 37°C after random allocation. Core temperatures and hemodynamic parameters were assessed in all patients at preoperative, intra-operative, and postoperative periods. Intra-operative shivering was also noted in both groups.

Statistical Analysis:

Unpaired and Paired Student's t-test.

Results:

For patients who underwent irrigation with fluid at room temperature Core temperature drop from 36.97°C in preoperative to 34.54°C in postoperative period with an effective difference of 2.38°C. Among patients who received warmed irrigation fluid at 37°C had core temperature drop from 36.97°C to 36.17°C and the effect of fall was 0.8°C. This difference was statistically significant (P < 0.001). Shivering of Grades 1 and 2 was observed in nine patients, of Group 1 while only three patients had Grades 1 and 2 shivering in Group 2. The hemodynamic parameters were similar in the two groups and did not reach significant difference.

Conclusion:

Use of warm irrigation fluid during TURP reduces the risk of perioperative hypothermia and shivering.

Inadvertent hypothermia in the operating theatre: an examination

Inadvertent hypothermia is a condition prevalent within the perioperative setting, since it has been estimated that as many as 70% of surgical patients suffer some degree of hypothermia (Litwack 1995, cited in Arndt 1999). This article will focus primarily on increasing the practitioner's awareness of patient risk and will discuss preventative measures. It will also provide the required underpinning knowledge to implement quality patient care.

Diagnósticos de enfermagem de pacientes em período pós-operatório imediato de colecistectomia laparoscópica

Os objetivos deste estudo foram identificar e analisar os diagnósticos de enfermagem de pacientes no período pós-operatório imediato de colecistectomia laparoscópica. Foi elaborado e validado um instrumento de coleta e registro de dados. Foram avaliados 15 pacientes adultos no período pós-operatório imediato de colecistectomia laparoscópica: 4 homens e 11 mulheres, com idade média de 45 anos. Os diagnósticos de enfermagem identificados foram: Integridade tissular prejudicada (100%), Risco para infecção (100%), Percepção sensorial perturbada (100%), Risco para aspiração (100%), Risco para função respiratória alterada (80%), Hipotermia (60%), Risco para temperatura corporal desequilibrada (40%), Nutrição desequilibrada: mais do que as necessidades corporais (33,3%) e Dor aguda (26,7%). Todos os pacientes foram admitidos em regime ambulatorial e receberam alta do Centro de recuperação pós-anestésica, apresentando ainda os diagnósticos de enfermagem Integridade tissular prejudicada e Risco para infecção.

Is Postanesthesia Care Unit Length of Stay: Increased in Hypothermic Patients?

Inadvertent hypothermia is one of the most common complications experienced by surgical patients who are transferred to the postanesthesia care unit (PACU). Appropriate pacu length of stay (LOS) is defined as the time required for a patient to achieve a physiologically stable condition after anesthesia administration. In studies measuring appropriate LOS, patients who arrived hypothermic in the PACU had longer stays than those who arrived normothermic. The aims of this study were to determine whether the actual and appropriate LOS in the PACU differs between hypothermic and normothermic patients and to identify differences between subgroups of patients according to age, gender, and type of anesthesia administered.

Cardiac output, pulmonary artery pressure, and patent ductus arteriosus during therapeutic cooling after global hypoxia-ischaemia

OBJECTIVE

To assess by Doppler echocardiography the effects of 24 hours of whole body mild hypothermia compared with normothermia on cardiac output (CO), pulmonary artery pressure (PAP), and the presence of a persistent ductus arteriosus (PDA) after a global hypoxic-ischaemic insult in unsedated newborn animals.

DESIGN

Thirty five pigs (mean (SD) age 26.6 (12.1) hours and weight 1.6 (0.3) kg) were anaesthetised with halothane, mechanically ventilated, and subjected to a 45 minute global hypoxic-ischaemic insult. At the end of hypoxia, halothane was stopped; the pigs were randomised to either normathermia (39 degrees C) or hypothermia (35 degrees C) for 24 hours. Rewarming was carried out for 24-30 hours followed by 42 hours of normothermia. Unanaesthetised pigs were examined with a VingMed CFM 750 ultrasound scanner before and 3, 24, 30, and 48 hours after the hypoxic-ischaemic insult. Aortic valve diameter, forward peak flow velocities across the four valves, and the occurrence of a PDA were measured. Tricuspid regurgitation (TR) velocity was used to estimate the PAP. Stroke volume was calculated from the aortic flow.

RESULTS

Twelve animals (seven normothermic, five hypothermic) had a PDA on one or more examinations, which showed no association with cooling or severity of insult. There were no differences in stroke volume or TR velocity between the hypothermic and normothermic animals at any time point after the insult. CO was, however, 45% lower at the end of cooling in the subgroup of hypothermic pigs that had received a severe insult compared with the pigs with mild and moderate insults. CO and TR velocity were transiently increased three hours after the insult: 0.38 (0.08) v 0.42 (0.08) litres/min/kg (p = 0.007) for CO; 3.0 (0.42) v 3.4 (0.43) m/s (p < 0.0001) for TR velocity (values are mean (SD)).

CONCLUSIONS

The introduction of mild hypothermia while the pigs were unsedated did not affect the incidence of PDA nor did it lead to any changes in MABP or PAP. Stroke volume was also unaffected by temperature, but hypothermic piglets subjected to a severe hypoxic-ischaemic insult had reduced CO because the heart rate was lower. Global hypoxia-ischaemia leads to similar transient increases in CO and estimated PAP in unsedated normothermic and hypothermic pigs. There were no signs of metabolic compromise in any subgroup, suggesting that 24 hours of mild hypothermia had no adverse cardiovascular effect.

The Synergy Model and the Role of Clinical Nurse Specialists in a Multihospital System

The role of clinical nurse specialists was formalized in the 1950s; the goal was to prepare inpatient, bedside nurses who would serve acutely ill patients via consultation and direct care. Clinical nurse specialists were to be expert clinicians, consultants, educators, and researchers. In the early stages of practice development, the focus was the specific needs of the assigned unit or floor. Organizational restructuring led to the elimination of many positions for clinical nurse specialists, with a shift of some of the nurses’ responsibilities to others (ie, managers) or the abandonment of some of the traditional roles. Recently, a reversal occurred in this trend, evidenced by a steady growth in the demand for these advanced practice nurses by organizations seeking to improve patients’ outcomes while remaining fiscally responsible. This demand led to changes in role expectations and expanded the responsibilities of clinical nurse specialists to a system-wide or organization-wide level. Contemporary practice of clinical nurse specialists is not well reflected in traditional role definitions or commonly accepted practice models. The Synergy Model, developed by the AACN Certification Corporation, was introduced as a way of linking certified practice to patients’ outcomes. The model describes 8 nurse characteristics and 3 spheres of influence. This article describes how a group of clinical nurse specialists applied the model to successfully change from a unit-based to a multisystem practice.

Residual neuromuscular blockade in the immediate postoperative period

Neuromuscular blocking agents are among the most potent and dangerous drugs administered in the course of a general anesthetic. Their residual actions can have profound effects on a patient's ability to adequately ventilate. Understanding the basics of their actions and the methods of monitoring the level of neuromuscular blockade will assist the PACU nurse in diagnosing the cause of postoperative muscle weakness and hypoventilation. This article will review the mechanisms of action and monitoring of neuromuscular blocking agents, as well as provide a basic overview of postoperative complications involving hypoventilation and motor weakness.