Effect of Local Anesthesia and General Anesthesia Using I-gel Laryngeal Mask Airway in Diabetic Patients Undergoing Cataract Surgery: Comparative Study.

BACKGROUND: Cataract surgery is one of the most commonly performed ophthalmic procedures. On choosing the appropriate method of anesthesia for diabetic patients with cataract whether regional or general, one should consider a technique that is associated with less stress response, minimal effect on hemodynamic and essentially associated with a good intraoperative glycemic control. This is yet to be determined. AIMS: The aim of this study is to evaluate the use of I-gel as an alternative to local anesthesia (LA) in diabetic patients undergoing cataract surgery. PATIENTS AND METHODS: This study was conducted on 60 controlled insulin-dependent diabetic patients undergoing cataract surgery. They were randomized to receive either LA by sub-Tenon's block (LA group n = 30) or general anesthesia (GA) using I-gel (GA group n = 30). Mean arterial blood pressure (MBP) and heart rate were monitored. Furthermore, blood glucose level and plasma cortisol level were measured at basal level, after induction of anesthesia or local block, after nuclear extraction, at the end of surgery, and 30, 60, 120, and 240 min postoperative.
RESULTS: There was no significant difference in either blood glucose or cortisol levels in both groups. Blood glucose level increased with induction of anesthesia in both groups. The use of I-gel was not associated with increase heart rate or MBP compared to the LA group.
CONCLUSION: Both local and GA using I-gel are relatively safe without marked changes in hemodynamics, blood glucose, or cortisol level in insulin-dependent diabetic patients.

INTRODUCTION

Diabetes is one of the most common metabolic disorders. Over the next decade, the exponential rise in obesity is predicted to increase the prevalence of diabetes by >50%. This has major implications on health services, with a particular impact on patient care.[1] Management of diabetic patients undergoing surgery is complicated by the endocrine and metabolic response to surgery.[2]

Surgery and critical illness activate the metabolic response to stress, which includes alterations in both hormone and cytokine concentrations. These, in turn, lead to both increased glucose production and a state of insulin resistance.[3] Diabetics also have been shown to have a higher risk of infection, postoperative inflammation, and delayed wound healing.

With aging, the incidence rate of lens opacity and cataract increases reaching 100% at the age of 90 years. Cataract is the most common surgery in elderly patients. In this category of patients, especially if diabetic, the risk of cardiac ischemia and coronary artery diseases increase during surgery. There is a concern that general anesthesia (GA) in these patients would lead to a more cardiac events as changes in heart rate and hemodynamic instability is observed among them.[4]

Regional block has many theoretical advantages over GA induces better postoperative analgesia, causes less nausea and vomiting, and lead to earlier patient discharge. However, most of the regional techniques produce cosmetic complications such as local bruising, hemorrhage, edema and subconjunctival ecchymosis near the needle entry site and long-acting muscle paresis.[5]

The I-gel is a novel supraglottic airway device that has been used as an alternative to tracheal intubation during GA. It is easily inserted, better tolerated, and with fewer hemodynamic and metabolic changes.[6] Hence, it could be a good alternative to endotracheal intubation for GA in short-time surgery like cataract surgery.

Alongside concerns about heart rate and metabolic responses associated with the technique of anesthesia either local or general, there is an additional concern in cataract surgery for diabetic patients, namely a good glycemic control. One of the major aims during cataract surgery in diabetic patients is the prevention of the progression of retinopathy and maculopathy.[4] The causes of such progression are multifactorial with poor glycemic control among them.

This study compared the effect of GA using I-gel versus local anesthesia (LA) on serum cortisol, blood glucose level, and hemodynamics (heart rate and mean arterial blood pressure [MBP]) in cataract surgery in controlled insulin-dependent diabetic patients.

PATIENTS AND METHODS

After obtaining approval from the Institutional Review Board (IRB) of anesthesia and Surgical Intensive Care Department, Faculty of Medicine, Mansoura University (IRB number R/112), informed written consent was obtained from patients before enrollment in this study. This double-blind, randomized prospective study was carried out in Mansoura University Ophthalmology Center during the period between June 2016 and January 2017. This randomized controlled trial was based on the revised CONSORT statement.[7] Randomization was achieved through sealed opaque envelops to avoid bias.

Inclusion criteria

A total of 60 insulin-dependent controlled diabetic patients of either sex, aged ≥18 years old, the American Society of Anesthesiologists physical status Class II, who were scheduled to undergo cataract surgery were enrolled in this study.

Exclusion criteria

patients <18 years, respiratory, cardiac or esophageal diseases, and potential difficult airway (mouth opening <2 cm, Mallampati Class 4, limited neck extension, previous difficult tracheal intubation) were excluded from the study.

Sample size

Power analysis using G*Power 3.01 by Franz Faul, Universitat Kiel, Germany. was done comparing serum cortisol 5 min after induction of anesthesia and at the end of surgery in LA (Group I). Effect sample size was 19 when alpha = 0.95, actual power = 0.8, and effect size dz = 0.6.

Preoperative assessment

All patients were investigated routinely for CBC, serum creatine, random blood sugar, and electrocardiography. Adequate glycemic control was insured by hemoglobin A1c <7.0%.

Controlled insulin-dependent diabetic patients with fasting blood sugar (90–130 mg/dl) were randomly allocated into two equal groups, Group I (LA) (n = 30) patients received LA by sub-Tenon's block and Group II (GA) (n = 30) patients received GA and the airway was secured using I-gel® (Intersurgical Berksheire RG41 2RZ United Kingdom).

Fasting strategy of our institute ensures a 6 h fasting for patients scheduled for surgery. Diabetic patients were not allowed to miss more than one meal. Fasting patients were, therefore, scheduled first in the operative list. No premedication was given to the patients. On arrival in the anesthetic room, two intravenous (i.v.) lines were inserted one for the collection of blood samples and the other for i.v. administration of fluids and drugs. A control blood sample was drawn before the patient was transferred to the operative room.

LA group (Group I) patients received sub-Tenon's block. After application of LA eye drops, small spring was applied to hold the lids open (painless). A small incision was made in the conjunctiva and was followed by the passage of a precurved blunted needle into space between it and the globe (the sub-Tenon's space) with infiltration of 3 ml of mixture of equal volumes of 2% lignocaine and 0.75% bupivacaine without adrenaline. The spring was removed, and a pad was placed over the eye.

All patients receiving LA were given oxygen 4 l/min through a nasal cannula during operation.

The GA group (Group II), after preoxygenation for 3 min with face mask, anesthesia was induced with 1 μg/kg fentanyl and 2.5 mg/kg propofol, followed by insertion of I-gel of appropriate size. Proper placement of I-gel was confirmed by square wave capnography trace, chest expansion, and ingress and egress of gases by auscultation in front of the neck of the patient. The factors considered for the failure of the proper placement of the device were failure to introduce into the pharynx, ineffective ventilation (inadequate chest rise, and abnormal capnogram), drop in saturation of peripheral oxygen <95% while insertion, the time taken to insert device exceeding 60 s, and malposition. GA was maintained with 60% oxygen in the air and sevoflurane 2%. Spontaneous ventilation was monitored so that end-tidal carbon dioxide tension was maintained at 35 mmHg ± 5.

Normal isotonic saline 0.9% was given to both groups as appropriate to their body weight and fasting hours.

Patients were monitored for their heart rate and mean blood pressure in the anesthesia room before operation then after LA injection or I-gel insertion at the following intervals 3 min, 5 min, 10 min, 15 min, 20 min, and at the end of surgery.

In addition to control sample, further venous blood samples were obtained after induction of general or LA, at the time of nuclear extraction, on completion of surgery, and 30, 60, 120, and 240 min after completion of surgery. The samples were centrifuged immediately for 5 min at 1200 g and the supernatant stored at −20°C. Blood glucose level and serum cortisol were measured enzymatically.

After operation, patients of the LA groups were allowed to eat within 2 h of operation, whereas the GA groups were not allowed to eat until after 4 h. This was in accordance with the usual clinical practice in our unit. Afterward, patients followed their usual insulin regimen; the need for extra dose of insulin given when fasting blood sugar exceeds 130 mg/dl was recorded.

Statistical analysis

Statistical analysis was performed using statistical package for social science (Version 18.0 for Windows; SPSS Inc., Chicago, IL, USA) statistical analysis package. Data were expressed as number, percentage median and range, and mean and standard deviation. Paired sample t-test was used to compare continuous variable in the same group with normal distribution. Independent sample t-test was used to compare continuous variables exhibiting normal distribution, and Chi-squared or Fisher's exact test for noncontinuous variables. P < 0.05 is considered statistically significant.

RESULTS

The following study was conducted on 60 patients of either sex who were subjected to cataract surgery, and they were controlled diabetic patients on insulin therapy. The two studied groups were comparable with respect to demographic data [Table 1].

Table 1

Demographic data of studied groups

	Group I (LA group)	Group II (GA group)
Age (years)	70.1±10.8	69.6±8.2
Gender, n (%)
Male	9 (30)	13 (43.3)
Female	21 (70)	17 (56.67)
Weight (kg)	71.1±5.3	68.4±2.7
Duration (min)	25.9±1.2	24.3±1.4

Data are presented as mean±SD. SD=Standard deviation. Gender is presented in number and percentage. GA=General anesthesia, LA=Local anesthesia

As regard hemodynamic parameters (heart rate and MBP) the heart rate increased significantly in Group II (GA group) compared to that of Group I (LA group) 3 min, 20 min after induction of anesthesia and to its basal value at 3 min after induction and at the end of surgery [Table 2 and Figure 1].

Table 2

Heart rate in beat per minute in the studied groups

	Before surgery	After induction	3 min	5 min	10 min	15 min	20 min	End of surgery
Group I (LA)	82.45±10.7	89.14±9.62	87±5.68	89.72±6.72	88.3±5.97	96.12±6.92	93.24±5.38	102.65±8.26
Group II (GA group)	78.11±4.62	88.16±4.62	114.4*,†±6.72	94.55±5.76	91.53±7.32	92.84±6.48	82.53±2.14†	103.32*±7.54
P	0.064	0.62	<0.0005	0.06	0.07	0.06	<0.0005	0.74

Data are presented as mean±SD. SD=Standard deviation. *Significant (P<0.05) when compared to the basal value in the same group, †Significant (P<0.05) Group II when compared to Group I. GA=General anesthesia, LA=Local anesthesia

Figure 1

Heart rate in the study groups

Table 3 shows that there was no significant change in the MBP between the two studied groups and only significant increase compared to its basal value in Group II at the end of surgery [Figure 2].

Table 3

Mean arterial blood pressure measured in mmHg in studied groups

	Before surgery	After induction	3 min	5 min	10 min	15 min	20 min	End of surgery
Group I (LA group)	102.45±13.6	115.1±14.25	100.67±6.58	89.45±5.27	85.22±6.75	87.61±10.8	92.47±7.32	109.58±9.71
Group II (GA group)	106.23±6.98	96.25±5.83	109.97±9.07	95.48±6.42	98.4±10.21	96.84±5.22	102.32±7.81	117.83±10.48*
P	0.18	0.19	0.06	0.07	0.06	0.06	<0.075	0.002

Data are presented as mean±SD. SD=Standard deviation. *Significant (P<0.05) when compared to the basal value in the same group. GA=General anesthesia, LA=Local anesthesia

Figure 2

Mean arterial blood pressure in the studied group

Blood glucose level increased in both groups significantly (P < 0.05) compared to their basal value after induction of anesthesia and with nuclear extraction in Group II [Table 4].

Table 4

Levels of blood glucose in mg/dl in studied groups

Blood glucose level (mg/dl)	Group I (LA group)	Group II (GA group)	P
Before induction	92.0±14.4	106.7±21.5	0.3
After induction	121.216.8*	131.6±20.7*	0.037
Nucleus extraction	114.6±20.6	133.4±26*	0.003
End of surgery	113.6±16.9	132.5±23.6	0.05
30 min	116.4±17.5	132.7±26.8	0.06
60 min	111.3±17.8	124.5±13.4	0.07
120 min	121.2±22.2	130.4±15.6	0.07
240 min	120.4±19.7	129.8±20.5	0.08

Data are presented as mean±SD. SD=Standard deviation. *Significant (P<0.05) when compared to the basal value in the same group. GA=General anesthesia, LA=Local anesthesia

Table 5 shows that plasma cortisol level significantly increased after induction, with nucleus extraction and at the end of surgery in both studied groups compared to their basal values.

Table 5

Levels of plasma cortisol in μg/dl in studied groups

	Group I	Group II	P
Before induction	9.7±3.6	11.6±2.8	0.06
After induction	10.4±4.02*	12.1±2.3*	0.049
Nucleus extraction	12.2±3.9*	14.8±3.8*	0.011
End of surgery	12.5±2.4*	15.6±3.4*	0.005
30 min	12.0±3.8	14.7±2.7	0.05
60 min	11.1±2.6	14.0±3.2	0.06
120 min	12.0±4.1	13.6±2.6	0.08
240 min	11.0±4.0	12.8±3.8	0.08

Data are presented as mean±SD. SD=Standard deviation. *Significant (P<0.05) when compared to the basal value in the same grou

DISCUSSION

Trauma associated with surgery results in increased production of stress hormones, the magnitude of which depends on the severity of the surgery or any postoperative complications. The increase in cortisol and catecholamine levels related to surgery reduces insulin sensitivity, whereas sympathetic activity decreases insulin secretion. Changes in the normal metabolic patterns due to surgery triggers gluconeogenesis, glycogenolysis, proteolysis, lipolysis, and ketogenesis ultimately resulting in hyperglycemia and ketosis.[8]

Good blood glucose control is important to prevent progression of diabetic retinopathy and maculopathy after cataract surgery. There was more concern about perioperative hyperglycemia than intraoperative hypoglycemia due to increased risk of infection, inflammation and poor wound healing. Currently, there is no internationally accepted guidelines specifically for the perioperative management of diabetic patients undergoing cataract surgery.[9]

Moreover, there is no specific guidelines for the type of anesthesia but is decided by the type of surgery and patient's preference. Regional anesthesia is preferred for some procedures in diabetic patients, especially cataract surgery, but it should be kept in mind that anesthetic requirements are lower and risk of nerve injury is higher in diabetic patients. Adding adrenaline to anesthetic solution increases risk of ischemia and edematous nerve injury.

In the current study, there was no difference in serum cortisol level between the two studied groups. This was contradictory to the findings of Barker et al., 1995[6] who reported increase in serum cortisol concentration in GA group in comparison to LA group. The same authors concluded also that the extent of the metabolic and hormonal response to cataract surgery in nondiabetic patients was abolished completely by performing the surgery under LA, whether by retrobulbar or peribulbar block.[10] This difference could be explained by the fact that they used endotracheal intubation for airway management, whereas in the present study, I-gel laryngeal mask airway (LMA) was used.

In this study, the blood glucose level increased in both groups with induction of anesthesia either regional or general but remained within the normal range. Suto and Hori[11] reported that changes in blood glucose and cortisol levels were minimal during and after phacoemulsification cataract surgery. These changes appeared to be related to alterations of the regimen for oral hypoglycemic agent and insulin due to fasting before surgery.

If GA is indicated, to restore the airway patency, a LMA may be used instead of endotracheal intubation as it cause less injury and lower risk of adverse reflexes compared to endotracheal intubation.[12]

In the current study, the use of I-gel in GA was as safe as regional anesthesia regarding metabolic and hormonal sequelae. Moreover, the use of I-gel was not associated with increase heart rate or MBP compared to the local anesthetic group despite insignificant increase in the heart rate with induction of anesthesia and the end of surgery compared to their basal values. These findings were similar to Bukhari et al.[13] that observed a significant increase in heart rate after insertion of airway device, but the increase was more in the endotracheal tube than in LMA group and similarly, the intraocular pressure (IOP) and the blood pressure. Braude et al.[14] and Wilson et al.[15] reported that endotracheal intubation was associated with a significant increase of hemodynamic variables compared to LMA insertion. Lamb et al.[16] carried out a similar study and demonstrated an attenuated response to hemodynamics as well as to IOP with the use of LMA compared to the endotracheal tube.

Release of catecholamine in plasma has been incriminated to play a role in the development of abnormal cardiovascular responses to laryngoscopy and endotracheal intubation. Attenuation of stress responses with the use of LMA may be due to diminished catecholamine release as suggested by Lamb et al. this could, in turn, be because LMA is relatively simple and atraumatic to insert.

CONCLUSION

LA is good enough for cataract surgery in insulin-dependent diabetic patients. If GA is needed for any reason, using I-gel is a reasonable option as it was not associated with increase blood glucose level or serum cortisol level or obvious changes in the heart rate or MBP.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.